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IN THIS ISSUE CIM MAGAZINE OCTOBER | OCTOBRE 2015

46

FIELD OF VISION

Once ignored, ore sorters are gaining wider acceptance as miners look to cut waste and spending By Ian Ewing

52

55

52 Hard lessons

The team at Palabora Copper, wiser for its Lift I block cave project, is drawing on that experience to go deeper By Michael Yang

55 A measure of control

Automated instrumentation is driving efficiency at mills by providing precise measurements throughout the processing circuit By Alexandra Lopez-Pacheco

October • Octobre 2015 | 5


16 14 8 10

Editor’s letter President’s notes

tools of the trade 12

The best in new technology

news 14

15 16 22 26

Compiled by Michael Yang

Dundee Sustainable Technologies introduces cyanide-free gold extraction process By Michael Yang

Letter to the editor Geologist launches crowd consulting and mentoring initiative By Virginia Heffernan

Colorado mine spill highlights cost of abandoned mine sites

columns

30 32

34 36 40 44

Briefs

By Kelsey Rolfe

28

underground mining

Revised standard takes environmental management to the next level By Paul MacLean

When is a Mineral Resource not a Resource? By Rod Webster

Keys to a no-surprise shotcrete system By Paul Rantala

Shaft mucking equipment has evolved to meet the demands of today’s tough jobs

contenu francophone

70

65

A new study provides insight into the impact of corrosion on support systems By Kelsey Rolfe

By Michael Yang

Alex Henderson details how existing technologies can deliver big gains By Peter Braul

74

Technical abstracts

80

Tete, Mozambique

Par Ian Ewing

60 60 61 70

82

Lettre de l’éditeur Mot du président Les actualités en bref

Durs enseignements L’équipe de Palabora Copper, désormais mieux préparée pour son projet de foudroyage par blocs de l’exploitation Lift I, puise dans son expérience pour aller plus loin

travel

mining lore

Champ visuel Alors qu’elles avaient jusqu’ici été ignorées des sociétés minières, les machines de triage deviennent une solution de plus en plus courante pour réduire les déchets et les dépenses

By Eavan Moore

The fight to sink the deepest single lift shaft in the United States

article de fond

By Lindsay Seegmiller

74

Par Michael Yang

Résumés techniques

Nearly a thousand years ago, Viking explorers set up the first iron smelting operation in the New World By Katelyn Spidle

La version française intégrale du CIM Magazine est disponible en ligne : magazine.CIM.org/fr-CA

6 | CIM Magazine | Vol. 10, No. 6


Innovative minds. Tangible results. Clients know us for our proven methodologies and extensive experience in the metals, energy, and infrastructure sectors, from process development through to plant operations improvement. For over 60 years, we’ve helped our clients solve their most difficult challenges by improving their complex processes, applying recent technological advances, and providing sound advice based on our global experience. Our team of problem-solvers stand ready to listen to your toughest problems and help you overcome them. To learn more, visit us at www.hatch.ca.

E N G I N E E R I N G • C O N S U LT I N G • P R O J E C T D E L I V E R Y • T E C H N O L O G I E S • O P E R AT I O N A L P E R F O R M A N C E


Editor-in-chief Ryan Bergen, rbergen@cim.org Executive editor Angela Hamlyn, ahamlyn@cim.org Managing editor Andrea Nichiporuk, anichiporuk@cim.org

editor’s letter

Advertising sales Dovetail Communications Inc. Tel.: 905.886.6640; Fax: 905.886.6615; www.dvtail.com Senior Account Executives Janet Jeffery, jjeffery@dvtail.com, 905.707.3529 Neal Young, nyoung@dvtail.com, 905.707.3525 Account Manager Mark Spasaro, mspasaro@dvtail.com, 905.707.3523 For Quebec: Info-Industriel Inc. Senior Account Executive Yvan Gauthier, ygauthier@cim.org, 514.576.5869

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eth R. Wilson enn Aw 5K

s ard

Finalist Be st

ment has been worthwhile. “If you have a poor measurement, or no measurement, you can’t do good control,” argues Philip Thwaites of XPS Consulting & Testwork Services in our technology piece on process monitoring, in which Alexandra Lopez-Pacheco details the technological advances that allow that measurement and control (pg. 55). It is a message that runs throughout this issue. The poor results that can come with too little information was among the hard lessons the operations team at Palabora Copper learned when it transitioned from an open-pit to a block cave mine. Now wiser, the company is applying those lessons to the work on the second block cave it is currently developing, including a much more comprehensive cave monitoring system. Michael Yang profiles that project on page 52. In the same vein, our feature story by Ian Ewing (pg. 46) zeroes in on the growing capabilities of ore sorting tools that can limit the time and energy lost when what should be waste rock is milled. In all of these instances, measurements provide control. Although we made the decision to focus on mineral processing and process monitoring in this issue months before we posted the video, the viewing data told us that we were on the right track. We know how people found the video, where they watched it, if and how they shared it and how long on average they watched. With this information and some finessing, we can fine-tune how we roll out and promote these videos in the future. In effect, it is our own foray into process monitoring.

Published 8 times a year by: Canadian Institute of Mining, Metallurgy and Petroleum 1250 – 3500 de Maisonneuve Blvd. West Westmount, QC H3Z 3C1 Tel.: 514.939.2710; Fax: 514.939.2714 www.cim.org; magazine@cim.org

ia ed

T

hanks to the steady and strong support from the people at McEwen Mining, earlier this year we created a video series of the “Innovation Lunch & Learns” that the company hosts at its Toronto office every few months. The presentations range from discussions on how and where step changes could potentially re-orient the mining industry to ideas for process improvements that can boost recovery rates by a few percentages. And, while these YouTube videos will never go viral, that a presentation on process optimization and froth flotation monitoring has garnered more than 1,000 views from people around the world suggests the media experi-

adian Busines sM Can in

Control is key

Section editors Peter Braul, pbraul@cim.org Tom DiNardo, tdinardo@cim.org Junior section editor Kelsey Rolfe, krolfe@cim.org Copy editor/Communications coordinator Zoë Koulouris, zkoulouris@cim.org Web content editor Maria Olaguera, molaguera@cim.org Contributing editor Eavan Moore, emoore@cim.org Editorial interns Michael Yang; Kate Sheridan, ksheridan@cim.org Digitization technician Marie-Ève Lapierre, melapierre@cim.org Contributors Elissa Ebersold, Ian Ewing, Virginia Heffernan, Leah Kellar, Alexandra Lopez-Pacheco, Paul MacLean, Paul Rantala, Lindsay Seegmiller, Katelyn Spidle, Rod Webster Editorial advisory board Alicia Ferdinand, Garth Kirkham, Vic Pakalnis, Steve Rusk, Nathan Stubina Translations Karen Rolland, CNW

Straits Resources’ Tritton Mine in New South Wales, Australia Photograph by Michael Evans

Ryan Bergen, Editor-in-chief editor@cim.org @Ryan_CIM_Mag

Layout and design by Clò Communications Inc. www.clocommunications.com Copyright©2015. All rights reserved. ISSN 1718-4177. Publications Mail No. 09786. Postage paid at CPA Saint-Laurent, QC. Dépôt légal: Bibliothèque nationale du Québec. The Institute, as a body, is not responsible for statements made or opinions advanced either in articles or in any discussion appearing in its publications.

8 | CIM Magazine | Vol. 10, No. 6

Printed in Canada


When the world looks to you Look to Petro-Canada Lubricants

Petro-Canada is a Suncor Energ gyy business TM

Trademark of Suncor Energy Inc. Used under licence.


president’s notes

A common goal Every industry has its diversity challenges, whether it is the technology sector, considered to be the most advanced and innovative or, not so surprisingly, mining. I only say that because the mining industry is still viewed as an “old boys’ club.” While this may have been true in the past, mining has come a long way and is, in some respects, one of the most progressive and innovative industries. We have led in many areas including automation, safety, environmental stewardship and corporate social responsibility, to name a few. There is no reason we cannot show the same leadership in regard to diversity. When I look around the CIM Council table, I have nothing but admiration for my female and male colleagues. They all bring a point of view and dynamic that is unique and helps make CIM better as a whole and the centre of excellence that it is now known to be. We may have come a long way but we have many leagues to go. Last year the Ontario Securities Commission (OSC) nudged the industry forward, enacting reporting rules that compels publicly listed companies to either detail the efforts they are making to improve female participation in their C-suites and boards or explain why they are not. Early indicators suggest that the majority of reporting companies are opting to comply with and adopt formal diversity policies. It is sad that, despite growing evidence that diverse boards can boost returns, we need to be pushed to make these changes. As the father of two teenage daughters, that is not acceptable to me, and it is not acceptable to them. I will encourage my daughters to follow the lead of Facebook COO Sheryl Sandberg, to “lean in” and take the responsibility to advance their own careers. We in leadership today, however, also need to put our shoulders to the wheel and bear our share of the responsibility. So let us all…lean in!

Garth Kirkham CIM President @GarthCIMPrez

10 | CIM Magazine | Vol. 10, No. 6


OF TOOLS THE TRADE

Silica, coal dust and diesel particulate matter are just some of the many dangerous airborne hazards that can circulate in mining workplaces. To stay safe in particularly dusty areas, miners typically have only two options: light but ineffective paper masks or bulky rubber ones. With this in mind, RZ Industries recently released its new M2 mesh air filtration mask, which combines the best of both options. The mask is made from an extremely lightweight, breathable and abrasion-resistant nylon mesh material that forms to the natural contours of the user’s face over time. According to marketing director Joe Klatte, the mask is capable of filtering 97 per cent of particles with a size of 0.1 microns or larger, keeping out particles like silica and coal dust. “This is because of the improved high-efficiency particulate arrestance (HEPA) filter,” he said. “The charcoal fibers in the HEPA filter collect and trap particulates like a magnet.” The filter can last up to eight hours in harsh environments before it needs to be replaced, and comes with the option of upgrading to a carbon element to deal with chemical fumes and odours.

Compiled by Michael Yang 12 | CIM Magazine | Vol. 10, No. 6

Extensive on-site analysis

Courtesy of Michelin Earthmover

Tires play a critical role in the productivity of haul trucks, directly affecting how much they can carry and how fast they carry it. “The biggest limitation on tires is usually the amount of heat generated on the crown, which can lead to premature wear and tear if they are pushed too hard,” said Mary Ann Kotlarich, spokesperson for Michelin. However, with Michelin’s new XDR250 tire, designed specifically for 250-ton (227 metric tonnes) haul trucks, the average operating temperature in the crown runs eight degrees Celsius cooler than preceding models. According to Kotlarich, this is due to a new, more ventilated tread pattern that utilizes smaller blocks and more grooves for better heat dispersion. The tire can also hold 9.2 per cent more air than its predecessors to accommodate heavier loads and comes with Michelin’s real-time tire monitoring system installed. “The XDR250 improves the tons per mile hauled of the trucks by up to 25 per cent compared to other tires on the market, and achieves it without sacrificing any tread life,” said Kotlarich.

Courtesy of SGS Minerals

Cool runnings

Getting quality mineralogical data is the number one priority for any company developing an exploration project. But if they wish to analyze the drill cores on site, they have only one of two options: use handheld spectrometers or ship the samples to a lab for more extensive testing. “Not only is shipping drill cores very expensive but, by the time they arrive, fractures and other changes from their natural state will have occurred,” said Hugh De Souza, director of geological services with SGS Minerals. However, with SGS’s Corescan mobile lab service, all drill cores and chips can be analyzed on site with its hyperspectral scanning technology. “The technology allows for continuous scanning and collects data from more than 150,000 data points, as opposed to the three or four ones with handheld spectrometers,” said De Souza. The lab also uses high-resolution digital photography and a breakage measuring system to document the original state of the underlying rock, and hosts the information on its cloudbased Coreshed software.

Courtesy of RZ Industries

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Honours and accolades at COM15

Making an impact on diversity

Geologist launches crowd consulting and mentoring program

Colorado mine spill highlights cost of abandoned mine sites

18

18

22

26

News

Full circle Dundee Sustainable Technologies introduces new closed-circuit cyanide-free gold extraction process By Michael Yang

Tom DiNardo

Dundee Sustainable about,” said Lalancette. Technologies (DST) is “It safely meets every ratcheting up its efforts single environmental to create a cyanide-free regulation in the world.” gold extraction process. The project received In early July the a $700,000 grant from company commisthe Quebec governsioned an industrialment in 2011, and $5 scale demonstration million from the fedplant in Thetford eral government in Mines, Quebec, capable 2013. of processing up to 15 Chlorination works tonnes per day of gold quickly, explained DST concentrate using its executive vice-president proprietary chlorinaDavid Lemieux, with a tion process. The plant Dundee Sustainable Technologies’ recently commissioned demonstration plant is capable of processing 15 tonnes per day of gold concentrate. reagent contact time of will produce about only one to two hours 10,000 ounces of gold under continuous operating conditions modernized to be much more effective rather than the days required by over the next two years to demonstrate and efficient,” said Jean-Marc cyanidation. It can also economically the effectiveness of the process and Lalancette, the developer of the tech- treat low-grade base metals, which othidentify any potential problems. nology and the company’s chairman. erwise require copious amounts of The first lot of material to be “And it comes at a perfect time for the cyanide to extract, and refractory ore, all processed is a gold/copper sulphide while consistently hitting similar gold industry.” concentrate from the Chelopech mine Growing concern around the world recovery rates at 94 per cent. in Bulgaria, operated by sister com“The process requires very little surrounding the short- and long-term pany Dundee Precious Metals. After water because almost all of the effluenvironmental effects of cyanide use that, the company is planning to move ents are recycled, and the mild condihave led to the chemical’s outright ban tions in the vat leaching reactors make into oxide and sulphide ores it sourced in many mining jurisdictions, such as energy costs much lower than cyanidafrom various North and South Amerithe U.S. states of Montana and Wistion,” said Lemieux. “The plant itself is can regions such as Canada’s Abitibi consin, and a number of Argentine also smaller than conventional leachgold belt and Argentina’s San Juan provinces. “However, with this ing facilities and can be built in a modprovince. process, waste only comes in the form ular manner. All of that makes the “Our approach is based on a histor- of barren and inert solids, meaning economics very good.” ical chlorination process that’s been there are no acidic tailings to worry 14 | CIM Magazine | Vol. 10, No. 6


news Closing the loop To achieve those results, a number of improvements to the original chlorination approach were needed. The chemical process, which involves adsorbing precious metals in highly reactive chlorine gas and then reducing the product to a metallic state, was first introduced in 1848 but faced two significant challenges: the high cost of reagents and the efficiency of precious metal recovery. “The best way to describe all of the advancements that address those problems is that we’ve managed to completely close the circuit,” said Lemieux. With a closed circuit, DST is able to fully recycle both reagents – namely chlorine and bromine – and water from the barren brine after the ore is leached, substantially cutting down on costly reagent replacements and leaving only solid residue that is much easier to deal with than liquids. Modern chemical engineering played the biggest role in closing the

letter to the editor Attention to fluid safety overdue I found your article “Debunked! 10 Maintenance Myths” in your June/July 2015 issue excellent and timely. Myth five, “Hydraulic systems are not a significant danger to maintenance employees,” in particular touches a strong note, and not just because it seems to draw from my 2015 CIM Convention presentation, “Improving Reliability, Cost and Safety with Fluid Power Systems.” When I first researched hydraulic system safety and fluid injection injuries, I was amazed at the lack of relevant statistics. I was also intrigued, when talking to people at the 2014 CIM Convention, as to how many experienced miners knew of somebody who had suffered such a tragic injury, while many others knew nothing about it. The best available statistics, though sparse, are eye opening. Australia’s New

loop. Instead of using a free halogen like chlorine right off the bat to leach the ore, the company found that sodium hypochlorite, as a hypohalide, could be effectively regenerated and reused continuously through a simple electrolysis step it developed. While hypohalides do not adsorb precious metals in the same way as halogens, the cheap and readily available chemical compound does generate chlorine and bromine gas when exposed to acidic elements.” This means that all we need to do is add sulphuric acid to the sodium hypochlorite in the vat leaching reactor to provide the necessary reagents, including catalytic amounts of bromine that react extremely quickly with gold, to leach the ore,” said Lemieux. From the reactor, the pregnant brine goes through a standard threestep process of filtration, adsorption and melting to produce the precious metals, leaving behind acid-free solid

South Wales (NSW) government surveyed its mining industry in 2010 and found, with only half the mines reporting, 1,186 fluid release incidents from the previous three years. Of those, 152 were classified as “direct contact” and 3.3 per cent of those resulted in serious injury or death. “Direct contact” incidents were actually three times as frequent as electric shock! Also, in 2010, the Sydney Hospital and Sydney Eye Hospital reported treating 2,460 cases involving high-pressure fluid releases. I am surprised at how many miners dismiss hydraulic system safety and, in particular, fluid injection injuries as nonissues. Leading-edge companies recognize a class of incident called “high-severity/lowprobability.” In evaluating risk, such companies ask: “Is such an incident likely to happen?” If the answer is “Yes, it’s happened at this site before” or “Yes, it’s happened previously in the industry,” the incident is deemed “likely” and is managed

waste and a solution of sodium chloride and bromide. “The regeneration of the hypochlorite from the solution to be fed back into the reactor with the next cycle is the critical step in the process and the second half of the closed circuit,” said Lemieux. The electrolysis cell used at this step is similar to standard cells used in the alkaline industry, with one prominent difference: it has no membrane. The cell is, therefore, much more resistant to contaminants like calcium and magnesium and requires no brine pre-treatment other than a simple pH adjustment and precipitation. The company has solidified plans to establish facilities similar to its Quebec demonstration plant in South America in the near future, after receiving federal government backing earlier this year for a 200-tonne-per-day concentrator in Chile and provincial support for the process in Argentina’s San Juan province. CIM

based upon severity alone. Fluid injection injuries are certainly high-severity and they have happened at many mines across the industry. See spectroline.com/fluidsafecase-study to learn how easily such injuries can occur. Australia is the world leader in hydraulic system safety in mining. The NSW government published MDG-41 “Guideline for Fluid Power System Safety at Mines” in 2010, which has been adopted country-wide and beyond. A growing number of Australian mines are adding a safety-formulated fluorescent dye to their hydraulic fluids in order to minimize the impact of fluid injection injuries. The Australian mining community tackled the myths surrounding hydraulic system safety and is seeing benefits. Is it not time we did the same? All my best, Timothy Ley Spectronics Corporation

October/Octobre 2015 | 15


Courtesy of Teck Resources

significantly decrease initial capital requirements and increase financial returns, while ensuring the project is developed in partnership with our neighbours, creating lasting benefits for residents in the region and our shareholders,” said Chuck Jeannes, president and CEO of Goldcorp, in an Aug. 27 press release announcing the joint venture. Goldcorp’s El Morro had Proven and Probable Reserves of 8.9 million ounces of gold and 6.5 billion pounds of copper as of Dec. 31, 2014. Teck’s Relincho project contains Reserves of 10.1 billion pounds of copper and 464 million pounds of molybdenum. – Leah Kellar Teck’s Relincho project contains Mineral Reserves of 10.1 billion pounds of copper and 464 million pounds of molybdenum.

Goldcorp and Teck combine Chilean projects Project Corridor is the interim name of a new joint venture between Goldcorp and Teck Resources to combine their respective El Morro and Relincho projects situated 40 kilometres apart in the Atacama region of northern Chile. The 50:50 joint management, announced in August, will commence when the transaction closes, which is expected to be in the fourth quarter of 2015. El Morro is an open-pit and underground gold-copper project west

of the open-pit Relincho site, a coppermolybdenum project. Project Corridor will be a standalone company with its own employees, management, executive team and board of directors. Projected benefits such as lower cost, improved capital efficiency and returns over either of the component projects, longer mine life of at least 32 years and a reduced environmental footprint are partly attributable to a conveyor that will transport ore from El Morro to a single mill at Relincho. “We now have an improved development approach that we expect to

GIVING BACK Kinross Gold is donating US$176,000 per year over the next three years to help U.S.based charity Project C.U.R.E. (Commission on Urgent Relief and Equipment) deliver medical supplies to Mauritania and Ghana, the company announced in June. Part of the funds will help finance the logistics around the procurement and delivery of 15 oceangoing cargo containers filled with X-ray machines, autoclaves, wheelchairs and operating tables. The remaining funds will support the charity’s Helping Babies Breathe program, which provides training and basic equipment for neonatal care to local health practitioners. The Canadian gold miner started working with the charity in 2012 and has already sponsored the delivery of medical supplies to three regional hospitals and 10 health centres across Mauritania in the last two years. – Michael Yang

16 | CIM Magazine | Vol. 10, No. 6

Barrick establishes one-president model Barrick Gold made some major refinements to its upper management structure this summer. The gold producer appointed Kelvin Dushnisky as the sole president of the company, a title previously shared between himself and co-president Jim Gowans, who will soon be retiring from Barrick. Gowans, who joined the miner last January, will remain with the company until Dec. 31 as an advisor to the chairman to help direct a number of additional personnel changes. “As we become leaner, more efficient and more keenly focused on a smaller number of core assets, we are empowering our leaders in the field to function as true business owners,” said Barrick chairman John Thornton in a press release. “[Gowans] has mentored and trained our operational leaders in this mindset,” said Andy Lloyd, vice-president of communications at the company. “The time was right to accelerate the transition.” The co-presidency was created in July 2014 following the departure of Jamie Sokalsky as CEO and the elimination of that position. Other changes include the appointment of Richard Williams as COO, having previously held the title of chief of staff. Also, Basie Maree was named CTO after serving the company as senior


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vice-president of technical services. The changes represent another step in the implementation of Barrick’s ongoing strategy to trim expenses by $2 billion by the end of 2016 and reduce debt. “This structure removes layers, eliminates bureaucracy and increases transparency in the organization, all of

which supports our key objective of maximizing free cash flow,” Lloyd said. – Katelyn Spidle

Making an impact on diversity Over the last half-century, mining, metallurgy and materials sciences have

marched steadily forward, but something about their culture has remained stuck in another era: female participation remains woefully low. “Forty-five years ago we had the same discussion,” observed Carolyn Hansson at the Women of Impact Symposium, a fullday forum at this year’s Conference of Metallurgists.

This year’s Conference of Metallurgists (COM) saw more than 300 presentations by the world’s finest minds in the field. The annual event, hosted by the Metallurgy and Materials Society of CIM (MetSoc), was held Aug. 23-26 at the Fairmont Royal York in Toronto, in conjunction with the America’s Conference on Aluminum Alloys, which added roughly another 100 presentations. University of Waterloo engineering professor Mary Wells, the chair of MetSoc and this year’s conference, kicked off the event with Monday’s plenary session and introduced presentations by Donald Sadoway of MIT and Maurits Van Camp of Umicore. Sadoway was particularly passionate about his view that metallurgists can have major positive impacts on the world: “I want bright young people who aren’t jaded, who are fearless and who don’t know everything is impossible.” In addition to sharing knowledge and excitement, the conference was an opportunity to honour the careers of important metallurgists of past and present. CIM past president Chris Twigge-Molecey, a senior advisor at Hatch, received the Airey award, Canada’s most prestigious metallurgy prize, in recognition of his various contributions to the sector throughout his career. Three honorary symposia at this year’s event included one dedicated to the memory of Lucy Rosato, who was president and CEO of CEZinc, covering sustainability in hydrometallurgy. The Torstein Utigard memorial symposium remembered the extractive metallurgy accomplish18 | CIM Magazine | Vol. 10, No. 6

Courtesy of the Metallurgy and Materials Society

Honours and accolades at COM

Mary Wells, a University of Waterloo engineering professor, is the chair of MetSoc as well as this year’s Conference of Metallurgists.

ments of the University of Toronto professor. To acknowledge his 65th birthday, David S. Wilkinson was honoured at a symposium in his name for his contribution to the science and technology of solid materials. The last day of the conference included a special Women of Impact symposium, which recognized female Canadian industry giants such as Ursula Franklin, an eminent metallurgist, activist and professor at the University of Toronto (U of T). – Peter Braul

• AWARDS • MetSoc Airey Award: Chris Twigge-Molecey, Hatch

Sherritt Hydrometallury Award: Ed Lam

MetSoc Student Chapter Award: Université Laval

MetSoc Innovation Award: The SART process

MetSoc Masters Scholarship Rebecca Radzinski, Queen’s University

MetSoc Brimacombe Award: Mansoor Barati, U of T

MetSoc Doctoral Scholarship Alexander Burns, UBC

Silver Medal: Mahi Sahoo, Suraja Consulting

MetSoc Best Paper Award W. Wulandari, G.A. Brooks, M.A. Rhamdhani and B.J. Monaghan “Kinetic analysis of silicothermic process underflowing argon atmosphere”

MetSoc Award for Research Excellence: Daolun Chen, Ryerson University

Light Metals Best Paper Award: C. Siemers, F. Brunke, K. Saksl, M. Kohnke, G.J. Ackland and B. Tegner “Development of oxidation resistant titanium alloys by niobium addition”

Gordon M. Ritcey Award – Alexander Burns, UBC

HYDROMETALLURGY AWARDS: CIM Fellowship – Roman Berezowski HYDROMETALLURGY SECTION SCHOLARSHIPS: Undergraduate Scholarship – Justin Riggio, McGill University

Non-Ferrous Pyrometallurgy Best Paper Award: J. Jansson, P. Taskinen and M. Kaskiala “Freeze lining formation in continuous converting calcium ferrite slags”

Lucy Rosato Scholarship – Caitlyn McKinley, Queen’s University

MetSoc Distinguished Materials Scientist Award: Akaram Alfantazi, UBC

CIM Fellowship: Roman M. Berezowski, James John Budac, Xinin Cao and Nils Voermann

MetSoc Environmental Award: Charles Q. Jia, U of T

CIM Distinguished Lecturer of MetSoc of CIM: Wilson Pascheto

CIM AWARDS


20 | CIM Magazine | Vol. 10, No. 6

Courtesy of the Metallurgy and Materials Society

Hansson was the first female student and PhD recipient in metallurgy at the Royal School of Mines at Imperial College in London. She was one of a number of women professionals at the event who shared their experiences as outliers in the industry, having carved out careers despite the odds. The symposium was a complement to the newly released Women of Impact in the Canadian Materials, Metallurgy, and Mining Fields (published by CIM), which profiles 18 women who have risen to prominence in these maledominated disciplines. MetSoc president Mary Wells, working with Anne Millar, a University of Ottawa PhD candidate in history, compiled the biographical sketches to help shed light on the countless career options available to women focused on these engineering realms. The symposium included a number of panels led by women featured in the book with each speaker bringing her own style to the format.

(From left to right) Liana Centomo, Priti Wanjara, Shari Graydon, Janice Zinck and Annette Bergeron discuss issues related to gender diversity in mining at the Women of Impact Symposium at this year’s Conference of Metallurgists.

Jennifer Jackman, the retired director general of CanmetMATERIALS, noted that throughout her early career she had to contend with the “subtle discrimination of lowered expectations” and later discovered how that attitude had changed her. “By the time I was a manager, I was too much of a fighter,” she remarked.

Janice Zinck, newly appointed director of Critical Metals at Natural Resources Canada, took her turn to lay down a list of professional strategies: “Define what success means to you”; “Get comfortable being uncomfortable”; and “Find your personal work-life balance.” All of these would have served the handful of male students in attendance


news equally well, but for her suggestion to make the most of being less common: “If you are a woman in science, you already stand out. And that’s a good thing!” Wells agreed with Hansson that it is frustrating that women continue to be under-represented in mining and metallurgy despite the discussion. She pointed to the need for structural changes in the workplace before meaningful progress can be made. Starting a family, for example, should not end a

career. “Employers need to give women flexibility to allow them to reenter the workforce,” she said, noting zinc refiner CE Zinc as a ray of hope. “There, all meetings end by 4:30, so people can go pick up their children if they need to.” The women’s success stories were a touchstone for many of the students.

Victoria Zyma, a third-year mechanical engineering student, said she felt more comfortable that she “could have a career and a family.” The most powerful message that Sarah Hall, a McMaster University chemical engineering undergraduate, took from the day was: “The career path – Ryan Bergen is not a straight line.”

Growing hair to show they care

As November approaches, the bare upper lip of many a man is itching in anticipation. During this month, men across the planet grow moustaches to raise awareness for men’s health issues, such as prostate and testicular cancer, and mental health as part of Movember. For the fourth year in a row, “Mo Bros” and “Mo Sistas” from the mining industry will be taking part in the friendly intra-industry competition dubbed “The Great Canadian Mining Challenge.” Last year 211 miners from 44 companies formed 16 teams to raise just over $70,000 for the cause. The team from BHP Billiton, “Average Joes with Awesome Mo’s,” raised the largest sum of money with a total of $17,294. To get involved, visit movember.com and search for the Great Canadian Mining Challenge. – Tom DiNardo

October/Octobre 2015 | 21


A Hive for hard times Geologist launches crowd consulting and mentoring initiative

A Vancouver-based geologist is hoping a new innovative opportunity will help place young geoscientists in a good position to weather the turbulent commodities market and come out on top. Andy Randell launched a crowd consulting initiative in April as an offshoot of his independent consulting work at Strata GeoData Services (SGDS). Called SGDS Hive, the idea is to bring together recent graduates of geoscience and other specialities such as environmental science to assess exploration projects, producing comprehensive reports that highlight mineral targets as well as social and environmental issues. The Hive concept promises to provide graduates with practical experience and deliver clients – mostly junior companies and prospectors – a quick and cost-effective means to advance their projects. Clients may also benefit from indirect access to new research and university facilities through recent graduates doing post-graduate work, as well as a broader range of expertise and potential full-time employees already familiar with the project should they ever require a permanent geoscientist. When the junior exploration market crashed in 2012, Randell was among its first casualties. Suddenly unemployed, the former chief geologist for Ryan Gold turned to consulting to pay the bills. “But I quickly realized I was a small fish in a very big pond,” said Randell, who graduated in environmental geoscience from Cardiff University in Wales in 1998 and has spent a large portion of his professional life on gold projects in Yukon. Randell found part-time work in a pet store, but a trained geoscientist selling cat litter did not sit well with him. “I don’t know exactly when the penny dropped but I thought that it would be good to have graduates 22 | CIM Magazine | Vol. 10, No. 6

Courtesy of Andy Randell

By Virginia Heffernan

The SGDS Hive team generated five targets on its test case, the McConnells Jest gold property (above) in Yukon.

working on actual projects and mentor them through the process of talking to First Nations, dealing with environmental issues as well as kicking rocks,” said Randell, who currently hires mostly graduates from B.C. universities and colleges but receives resumés from around the world. SGDS Hive team members work remotely, storing maps and text in Google Drive, a free cloud-based storage service that allows individuals to collaborate on projects. The team members keep track of their hours, but the schedule is flexible, allowing them to work around other employment and study commitments. The team uses QGIS, a free open source geographic information system, for mapmaking. All the project information is password protected to ensure confidentiality, but clients can monitor developments in real time. Once a project is completed, Randell removes the information from the cloud and backs it up on a hard drive. The test case was the McConnells Jest gold project in Yukon. Claim owner Bill Koe’-Carson wanted to narrow down targets on his 3,371-hectare property within the Tintina gold belt. The Hive team for this project, consisting of three recent graduates super-

vised by Randell and one GIS consultant, generated five targets based on geological interpretation of current and historical data. When Koe’-Carson returned to the property in August, he sampled surface mineralization on all the Hive targets he was able to investigate. Assays are pending. “This was not just a summary report incorporating data interpretation,” said Koe’-Carson. “This was clarity of vision and direction for me, in a neatly presented package. Given the chance to showcase their underutilized talents, the team seized the opportunity with a zeal rarely seen these days from more jaded veterans.” Beyond delineating targets, the report (which follows a National Instrument 43-101 format but does not qualify as one because there was no site visit) addresses the environmental and social issues that might arise on the traditional territory of the Na-Cho Nyak Dun First Nation. The completed report was shared with the Nation. Randell said he believed the report was appreciated by the First Nations there, adding that “they really liked the fact that Bill spoke to them and was aware of the archeological sites and rare plant species in the area.”


He sees Hive not just as an altruistic venture but as essential training for the generation of geoscientists who will replace those currently retiring or turning to other careers as the bear market for commodities growls on. Although Randell completed the McConnells Jest report for free in exchange for the freedom to showcase the results, he is currently managing paid contracts that remain confidential for now. He pays his team members $25 per hour, basing his bids on how many hours he estimates the project will take. Most of the team members, including Randell, continue to work part-time jobs in retail. Although Hive is only a few months old, Randell is already receiving recognition both at home and abroad. Geoscientists in Australia are interested in replicating the crowd consulting concept, while the BC Association of Professional Geoscientists and Engineers (APEGBC) has asked Randell to host the student orientation day at AME BC’s Mineral Exploration Roundup in January. “A lot of people are looking for opportunities to learn during this downturn,” said Randell. “At some point our industry will return, and these graduates will be required to run exploration programs, so it’s important that they remain engaged.” CIM

Courtesy of Nexen Energy

news

Nexen Energy discovered a pipeline rupture at its Long Lake oil sands project in July.

Suspension lifted for 40 pipelines at Nexen’s Long Lake facility The Alberta Energy Regulator (AER) has approved the partial resumption of pipeline operations related to utilities at Nexen Energy’s Long Lake oil sands facility, the company announced in September. A pipeline rupture discovered by the company at its Long Lake project in July prompted it to launch an inter-

PROJECT PIPELINE

True North Gems received US$4 million of new funding for its Aappaluttoq open pit ruby mine in Greenland from a share purchase and option agreement with Greenland Venture A/S, the company announced on Aug. 26. The new funding is enough for it to move the mine into the production phase, which was expected to begin by end-September. The project’s prefeasibility study, updated in March, estimated that the total capital costs this year would be around US$20 million. The project has Probable Mineral Reserves of about 167,000 tonnes and an expected mine life of nine years. – Kate Sheridan Red Eagle Mining has started construction at its Santa Rosa gold project, the company announced on Aug. 18. The construction of the San Ramon mine, expected to cost

nal audit of its pipeline management, which uncovered a number of noncompliance issues. The findings led AER to suspend 15 pipeline licences and shut in 95 pipelines at Long Lake in August. AER amended that suspension order to allow Nexen to reopen 40 natural gas, fuel gas and fresh water pipelines at the operation following an inspection of the facility’s maintenance and monitoring documentation. The suspension order that remains affects

US$74.2 million, will last until the second half of 2016 when production from the underground shrinkage stoping operation will begin. The mine will be Colombia’s first new gold producer in 20 years with an annual production capacity of 50,000 ounces of gold over its eight-year mine life. Proven and Probable Reserves are estimated at 2,424,000 tonnes at a grade of 5.2 grams per tonne of gold. – Michael Yang Vale approved construction of an underground nickel mine at its Voisey’s Bay site on Aug. 10. The mine, slated to begin construction next year, will replace the site’s surface mine, in operation since 2006, and will have an annual capacity of around 40,000 tonnes of nickel. It is expected to extend the site’s life by almost 15 years. – Kelsey Rolfe

October/Octobre 2015 | 23


55 pipelines containing natural gas, crude oil, emulsion, salt water and fresh water. Partial resumption will allow Nexen to maintain about 75 per cent of oil sands production and upgrader operations. “Following AER inspections of the site, a review of documentation and

Nexen’s subsequent actions, the regulator is satisfied that the current operating conditions of the utility lines pose a low risk to public safety and environmental protection,” said an AER press release. “Nexen has demonstrated to AER that these utility lines can be operated safely and within all regulatory requirements.”

AER said it is required to follow a rigorous daily and weekly inspection plan of the affected lines and to provide regular updates of the results. Ryan Bartlett, an AER spokesperson, said that there was no timeline in place for the remaining 40 pipelines to be brought online, and that the regulator was working with Nexen to determine the appropriate next steps. – L.K.

Anglo American offloads Chilean assets

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London-based diversified miner Anglo American sold two of its openpit copper mines in August to an investor consortium. Spearheaded by Audley Capital Advisors LLP, the consortium paid a total of US$300 million upfront for the Mantoverde and Mantos Blancos mines, located in northern Chile. If Audley Capital pursues an expansion of Mantoverde to extend the mine’s life, the interest’s value could increase by almost US$200 million in the coming years. “I am delighted that, together with Orion, we are to acquire the Mantoverde and Mantos Blancos mines in Chile,” said John MacKenzie, CEO of mining at Audley. “I know both of these operations well and can see the scope to further enhance the business under our ownership, particularly in terms of their life extension potential to meet our expected view of constrained copper supply in the medium and longer term.” The sale is part of Anglo American’s commitment to lighten its debt, which reached US$12.9 billion by end-2014. The company will focus its efforts on maintaining its largest and most lucrative copper projects: Los Bronces and Collahuasi in Chile, and Quellaveco in Peru. It also recently sold coal assets and four platinum mines in South Africa, as well as some coal operations in Australia. “The sale of our Norte copper assets to the Audley consortium represents a good outcome for Anglo American, both in terms of the up-front value achieved, the potential upside geared


to the copper price and the continued delivery of our asset disposal programme,” said Mark Cutifani, CEO of Anglo – K.S. American.

Eldorado suspends Greek operations Eldorado Gold recently reported more bad news from its Greek operations. Hellas Gold, a subsidiary of the Vancouver-based miner, suspended all mining and development activities at its Stratoni mine and Skouries and Olympias projects, located in the Halkidiki region of northern Greece, in August after the country’s Ministry of Energy revoked the company’s technical studies. The subsidiary confirmed it is taking legal action against the ministry’s decision by filing an injunction request with the Council of State – Greece’s Supreme Court on administrative and environmental affairs. Energy said the technical studies were in violation of the country’s requirements because they were partly conducted outside of Greece. Eldorado carried out pilot-scale test work on a smelting process at an Outotec facility in Finland. The revocation forced Hellas Gold to suspend the majority of its 2,000 employees for a period of three months, in accordance with the country’s labour laws. Certain employees will continue to work on maintaining environmental protection measures during this period. If the ministry refuses to reinstate Hellas’ permits after three months, the company will be forced to lay off its entire staff. “Eldorado cannot and will not continue to allocate expenditures to our projects in Greece while the Ministry of Energy is openly hostile to our activities, as evidenced by recent ministry decisions,” said Eldorado CEO Paul Wright in a statement. “We sincerely hope to resume our activities in Halkidiki at some point in the near future – preferably through constructive engagement with the Ministry of Energy rather than a court decision.” – K.S.

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Gone but not forgotten Colorado mine spill highlights cost of abandoned mine sites By Kelsey Rolfe Contractors for the Environmental Protection Agency (EPA) were investigating a persistent leak at the abandoned Gold King mine near Silverton, Colorado in August, when an equipment operator accidentally breached a pile of debris with a backhoe. The sludge that ran into the Animas River system contained lead, arsenic and cadmium at levels well beyond regulated safe exposure limits, turned the water a vivid mustard hue, and revealed the thorny problems that come with rehabilitating closed and abandoned mines. There are about 23,000 abandoned mine lands in Colorado, and at least 500,000 abandoned mine sites across the United States, according to government figures. The responsibility for their maintenance and rehabilitation, if the

owners cannot be found, falls to the states in which they reside. However, if a site is considered seriously hazardous, it can be nominated to the EPA’s Superfund national priorities list, which currently contains around 130 abandoned mine lands. After a preliminary assessment and a site inspection, the EPA uses its hazard ranking system to assess the site’s potential to pose a threat to human health and the environment. Sites on the priority list eventually receive Superfund money from the federal environmental program established under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) of 1980. The act gives the EPA the ability to clean up abandoned hazardous

waste sites, and to compel liable parties to clean up the sites or reimburse the EPA’s cleanup costs. Gold King was a candidate for Superfund designation prior to the spill, but locals fought it for years, arguing it would stifle the local tourism industry – a major economic driver in the area. After the spill, however, Silverton and the San Juan County Commission passed a joint resolution to petition Congress for Superfund money. Silverton’s initial resistance to Superfund dollars is not uncommon. Along with the promise of site rehabilitation, Superfund status comes with a strong stigma of being designated a hazardous waste site. “Superfund is not the answer, because it’s so devastating for the communities

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26 | CIM Magazine | Vol. 10, No. 6


news around the property,” said Todd Hennis, the owner of Gold King. Unlike the United States, Canada has no Superfund program, but it does have a comparable management strategy for its roughly 10,000 abandoned mine sites. Responsibility for their upkeep and rehabilitation falls to the provinces, as the constitution granted them control over natural resources. The territories, however, have different arrangements under their devolution agreements. Aboriginal Affairs and Northern Development is liable for the costs of seven sites in Yukon, while the territorial government is responsible for ongoing care and remediation. The federal department monitors all identified historic contaminated sites in the Northwest Territories. It also is responsible for any maintenance costs in Nunavut, which has not yet negotiated devolution. Because the sites fall under provincial jurisdiction, remediation efforts – and the public reporting of those efforts – vary across the country. Ontario, for example, operates an online database as part of a wider program to track abandoned mine hazards. “Through the program, Ontario has invested more than $140 million and rehabilitated more than 80 of the highest-priority abandoned mine sites in the province,” said Julia Bennett, a spokesperson for the province’s Ministry of Northern Development and Mines. Manitoba has

spent more than $200 million since the beginning of its Orphaned/Abandoned Mine Site Rehabilitation program in 2000, which included funding for five high-priority sites that have been fully remediated. The infographic above highlights findings from a CIM Magazine analysis of publicly reported data on abandoned mine site management. CIM

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ISO 14001

Revised standard takes environmental management to the next level BY PAUL MACLEAN

early 20 years after it was first published, ISO 14001 has become the world’s most widely recognized environmental standard, with more than 250,000 mainly industrial organizations using it as a foundation for their environmental management systems (EMS). The mining industry relies heavily on the standard, as it provides a dependable channel through which stakeholders can gain assurance that a mine and its owners systematically address environmental impacts. ISO 14001 was initially published in 1996 and revised for the first time in 2004. Since 2011, it has undergone a major overhaul, resulting in the publication of the ISO 14001:2015 International Standard in September, when it went into effect. This revision marks an important milestone for organizations that use the standard. Since the mid-1990s, methods for the management of risks associated with air emissions, water discharges, waste and natural resource consumption have evolved, as have the expectations of regulators, landowners and the public. The environment has become a strategic business consider-

N

ation at all stages of projects, from early exploration to mine closure. It is a complex management challenge and warrants significant investments in technology and human resources. The obstacles it raises must be overcome by core business functions like investor relations, regulatory affairs, communications and procurement. Faced with an array of other obligations regarding stakeholder rights, payment disclosures and product traceability, many companies are repurposing their health, safety and environment systems to encompass social responsibility, or are choosing to develop corporate responsibility systems that integrate the environment. This trend is an underlying theme in ISO 14001:2015. To maintain its relevance as the global reference for environmental management systems, ISO 14001:2015 requires that organizations examine the broad context in which they operate, taking into account value chain considerations and the expectations of stakeholders. It also requires that an organization’s leadership assume more accountability for environmental performance and greater integration of environmental considerations in business decision-making. Here are three important concepts in the new standard:

Context of the organization

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Organizations must demonstrate in their EMS an understanding of the conditions and factors that could affect their environmental management, such as climate change, natural resource availability and constraints, the quality of water and air, and the regulatory framework. The organization’s social context in particular, specifically the needs and expectations of interested parties (which can include governments, investors, employees, communities, aboriginal groups, customers, et cetera), must be taken into account. It must identify the interested parties that are relevant to its EMS and consider their needs and expectations when identifying its compliance obligations.

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28 | CIM Magazine | Vol. 10, No. 6

Formerly under the heading “Legal and other requirements” in the 2004 version of the standard, “Compliance obligations” are consid-


columns ered as possible sources of risks and opportunities to organizations. Organizations are now required to maintain documentation of their obligations and action plans to address them. Obligations can include applicable laws and regulations, industry standards and codes of practice, as well as requirements arising from agreements with interested parties.

Life cycle thinking When organizations examine their environmental aspects and assess the degree of control they have to prevent or mitigate associated impacts, they are now required to also include impacts arising from the use of products (e.g. chemical products, additives, components or parts) and their treatment or disposal at the end of their useful lives. While this does not mean that a life cycle analysis of these products must be performed, it does imply that controls should be established in the design and development process of products or services, considering each stage of the life cycle. Organizations must also establish environmental requirements for the procurement of products and services, and control or influence any outsourced processes. Much of the structure of the standard has changed substantially in order to incorporate these new concepts, although it does preserve some elements of the familiar 2004

version. The table of contents, for example, is based on a new high-level structure for documentation that is now common to all ISO management standards, to enable integration with other topics such as health and safety as well as quality (both of which have impending new or revised ISO standards as well, with the development of ISO 45001 underway and ISO 9001:2015 expected by the end of this year). ISO 14001:2015 is designed to help organizations revitalize, restructure and improve their environmental management practices while pushing corporate environmental performance to a higher level. As markets and mentalities have evolved, the standard needed updating to stay in line with today’s thinking about environmental issues, and to integrate sustainable development concepts better. With the new version, any type of organization wishing to prepare for the environmental challenges and business opportunities of the future will have a stable framework of requirements for the next 10 years or more. CIM Paul MacLean is president and founder of EEM Sustainable Management, a Montreal-based boutique management consultancy that has provided leadership in environmental and social responsibility to a wide variety of multinational and local industries, as well as aboriginal organizations since 1993. Paul has directed environmental and social management projects in Canada, the United States, Africa, Asia, and Europe.

October/Octobre 2015 | 29


MINERAL RESOURCES AND RESERVES

When is a Mineral Resource not a Resource? BY ROD WEBSTER

any mining companies are cutting exploration budgets to survive the current mining downturn and low commodity prices. As a result, some firms either do not have enough geological and support staff or they have inexperienced staff members who do not adequately understand the geology, mining method used and processing aspects of their operation or project. This can negatively impact the quality of Mineral Resource or Reserve estimates and statements as well as the preparation of long-term mine plans. When a company lacks proper staffing, the quantity of the remaining Mineral Resources and Reserves after initial mining suffers. Some mines, for example, now live a hand-tomouth existence, with enough defined Mineral Reserves for only a year, or perhaps just a few months, due to a lack of drilling, geological evaluation and mine planning. Some mines are being forced, because of this dearth of defined

M

Measured and Indicated Resources, to include Inferred Mineral Resources (as defined by the National Instrument 43101 code) as Reserves. Both instances result in a limited understanding of possible dilution and ore losses, stemming from a poor understanding of the mineralization, geology and geotechnical issues. Most international reporting standards define Mineral Resources as having “a reasonable prospect of eventual economic extraction.” The company CEO and investors must ask if this requirement is being overlooked or ignored to keep the remaining reported Mineral Resources at a reasonable level to maintain the share price. Is the modest exploration that is now being carried out concentrating on known areas of higher grade in order to maintain the company’s key market-related performance indicators? Companies should focus on areas necessary to underpin their medium- to longer-term future. It is a frustrating catch-

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columns 22 situation, where a lack of reported Mineral Resources and Reserves, due to limited exploration and geological modelling, or even doubts as to the quality of those Resources and Reserves, lowers the perceived value of a company. This results in a lower share price, a reduced ability to raise funds and a need to conserve existing funds. It also reduces a company’s ability to undertake exploration, Mineral Resource modelling and mine planning resulting in a further reduction in Mineral Resources and Reserves. Other problems that have been recognized recently in the estimation and reporting of Mineral Resources and Reserves include: • Inclusion of low-grade Mineral Resources located deep below the surface, when it is unlikely that this material can be mined by underground means at such a low grade or by open-pit methods at that depth. • Substantial tonnages of Mineral Resources and Reserves being based on one drillhole intersection, with the influence of that intersection being unreasonably extrapolated. • Large areas of what is most likely barren material being classified as Mineral Resources and Reserves due to “smearing” (or spreading) of high-grade drillhole intersections into areas of limited data by inexperienced resource modellers. • A percentage of the remaining Mineral Resources and Reserves being based on very narrow veins adjacent to previously mined underground voids, which would most likely never be mined based on the vein width, grade, geotechnical issues and, if applicable, cost of backfill. • Crown and sill pillars being included in Mineral Resources and Reserves where there are no reasonable prospects of mining due to ground support or surface environmental issues. • The classification of Mineral Resources, and hence Reserves, being based only on statistical parameters (generally distance to samples) and not on geology or trends in mineralization. • Insufficient understanding and use of geological interpretations during Mineral Resource modelling and grade estimation, due to advances in software and extensive use of statistics. This results in models not properly representing the mineralization, especially around the margins, of many advanced mines. • Areas of previous underground mining not having been removed from the Mineral Resource and Reserve statements. • Poor allowance being made for the minimum mining width within narrow veins, resulting in excessive dilution and a lowering of the mill head grade below that required to be economic. • Poor auditing of Resources and Reserves for operating mines. • Limited due diligences being carried out on existing Mineral Resources and Reserves by potential purchasers of existing mines or recent discoveries.

Substandard estimation and reporting of Mineral Resource and Reserves can lead to serious problems. Shareholders and company directors need to know the true value of a company, and one of the most important measures is the quantity and quality of the Mineral Resources and Reserves. Having the necessary qualified and experienced staff, either in-house or on hand, to carry out detailed project-focused exploration, high-quality Mineral Resource and Reserve estimation and practical mine planning with sound geotechnical input is a necessity, not a nicety. CIM Rod Webster works for AMC Consultants in its Toronto office and has more than 35 years of experience as a geologist, working mainly in resource and reserve estimation, review and reconciliation. His experience covers all facets of general geology but has focused on deposit evaluation, from initial drilling through to deposit definition and resource estimation.

October/Octobre 2015 | 31


O P E R AT I O N S

Keys to a no-surprise shotcrete system BY PAUL RANTALA

well-functioning shotcrete system is like the air we breathe: you take it for granted when it is there, but problems escalate quickly if it is not. The focus of mining companies is on extracting ore from a mine. But that extraction can stall if shotcrete is not available where and when it is needed. It is therefore essential to achieve a no-surprises shotcrete system for underground mining operations.

A

Design your shotcrete system for the life of the mine Reliable shotcrete supply begins at the mine’s design stage. It is important to determine how much shotcrete will be required throughout the life of the mine, and how far and deep it must be transported, so that choices in the design of the shotcrete system along with choices for the rest of the mine are made in tandem. Similar to other components of a mine’s infrastructure, such as a backfill system, a shotcrete system must consider available resources, constraints, opportunities

32 | CIM Magazine | Vol. 10, No. 6

and synergies with other systems. For example, the work of building a shotcrete-delivery system must be done at times that avoid conflict with ore extraction. The shotcrete, however, must be available when it is needed, so as to not delay the mine’s expansion. The next issue is how to deliver the shotcrete to where it is needed. In the early stages of a mine’s life, and for places where only small volumes of shotcrete are needed, it may be best to use bags of dry-mix shotcrete, as the product can be carried on mine vehicles to where it is needed, without a pipeline system. But if higher volumes are required, the mine operator must determine the best method of moving wet shotcrete produced on the surface to the necessary location. One way is through pipes called slicklines that run down the mine’s shaft, fastened to the shaft walls. The other is to drill boreholes lined with piping through the rock from the surface down to the stopes.


columns In-shaft slicklines may cost less to construct, but a break or a leak could shut down the shaft’s skips or cages until the slickline leak is fixed. Boreholes generally have a higher construction cost but avoid risk to the operation of the shaft, which is the mine’s lifeline.

Therefore, it is important to also employ consultants who can provide a wider view of the situation. That said, vendors and consultants are not as familiar with the mine as are the staff employed by the mine. As with much of mining, success is achieved through the right balance of wisdom from vendors, consultants and employees of the mine. CIM

Budget time and money for monitoring and maintenance In deciding how to transport the shotcrete, designers must clearly understand the difference between the higher capital cost of drilling shotcrete-specific boreholes from the surface versus the higher risk and operating costs of an inshaft slickline. Budgeting enough resources for monitoring and maintenance is vital for two reasons. Firstly, it is important to provide reliable supplies of shotcrete to the right parts of the mine. Secondly, the potential for a breakdown in the shaft can be extremely detrimental to safety and ore production operations. Due to the abrasiveness of the product and its velocity in the pipeline, there is also a strong potential for wear on any pipe carrying shotcrete. Studies indicate that by falling through a vacuum, a mass of shotcrete can reach speeds of 50 to 100 metres per second. This results in serious differential wear on the inside of the pipe, on about 10 per cent of its circumference, and can cause pipeline failure. The greatest erosion occurs at the interface between the freefalling shotcrete and the shotcrete that has filled the lower portion of the pipe that is restricted by the outlet design. Envision bedrock at the bottom of a waterfall that has been eroded into a bowl, for instance. The high turbulence at this interface zone, where the shotcrete changes speed, can be the highest erosion wear part of the shotcrete system. Frequent inspection of the pipe using technologies similar to those used to inspect underground backfill system such as pipeline cameras and ultrasonic thickness testing can help avoid problems. Replacing vulnerable sections of the pipe using high-tensile and harder steels and possibly adding ceramic liners can similarly improve reliability.

Use vendors and consultants effectively Many mining engineers are well versed in matters related to the effective application of shotcrete in order to achieve a safe and reliable mine. But they naturally focus on extracting ore, rather than on developing a strategy to ensure the right formulations and volume of shotcrete is available when needed. Because shotcrete systems are not core to mining operations, mining companies often need to look outside for expertise on shotcrete strategy. Vendors of equipment, concrete and admixtures can be a useful source of information for their products, but it is important to remember the limitations under which vendors work. They are restricted to solutions made by their company and thus are understandably motivated to sell those solutions.

Paul Rantala, P.Eng., is principal consultant with Kovit Engineering Limited in Sudbury, Ontario, which recently merged with Outotec. Paul is also owner of PAR Innovations Inc. that developed the unique Pipeline Pressure Pill test to troubleshoot backfill, slurry and shotcrete piping systems. paul.rantala@koviteng.com (paul.rantala@outotec.com), 1.705.523.1040 ext. 203.

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October/Octobre 2015 | 33


AP - Ross D. Franklin/The Canadian Press

Building a better shaft mucker Equipment has evolved to meet the demands of today’s tough jobs By Eavan Moore A new shaft mucker design was used at Resolution Copper in Arizona to sink shaft 10.

new shaft mucker design developed by Cementation and Mining Technologies International (MTI, now Joy Global) substantially reduced maintenance costs for Cementation and performed well on a shaft-sinking project at Resolution Copper, completed in 2014. The new design, dubbed VSM 14, is an improvement on previously existing technology. Vertical shaft muckers have long, extendable booms that reach down to the shaft floor, with jaws on the end that pick up material and drop it in separate containers for removal. By strengthening the boom and downsizing the jaws, the new design reduces the stresses on the boom without losing operating speed.

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Shaft muckers The original vertical shaft mucking machine was invented in the late 1940s and began to be widespread in North American mines starting in the 1950s. Known as the Cryderman mucker, it was distinguished from other shaft muckers by its pneumatic cylinders and pneumatic telescoping boom. The boom is anchored to a galloway – a multi-stage platform in the shaft that supports equipment and personnel – and can reach down into the extremities of the shaft. The original Cryderman design was adapted in different sizes. The largest version of this design quickly became popular in both Canada and the United States, but it was not used in Cementation’s work until 2005. (Cementation had used the original Cryderman design and another type of shaft mucker, called the cactus grab, usually more popular in South Africa.) The machine that Cementation used while sinking the Main and Vent shafts at Xstrata’s (now Glencore’s) Nickel Rim South project in 2005 racked up enormous maintenance expenses for an otherwise successful project, according to Ryan Gough, manager of project services at Cementation Canada. “We spent an astronomical amount of money on spare parts,” he said. “It was in excess of $1 million.” The biggest problems centred on the extendable boom. Several booms failed at the same spot, a transition zone where the inside diameter of the boom changed. If they did not fail, 34 | CIM Magazine | Vol. 10, No. 6

the booms had a tendency to bend, which prevented them from being retracted and required them to be replaced before mucking could resume. “Generally the bent booms could be placed on a press and straightened,” said Gough, “but it obviously took considerable time to repair a boom and caused significant delays in the shaft.” There were other problems as well: cracked jaws, centre pipe failures and dirt accumulating in the jaw cylinder shroud, which then damaged the cap and seals on the stationary boom. In 2006 Gough approached the equipment manufacturer MTI about collaborating on a redesign. MTI had not built shaft muckers of this type but was willing to help find solutions. A design team met with Cementation’s project services engineers, as well as site operations and maintenance, with the objective of building a machine with higher reliability, lower maintenance costs and performance changes that would better suit Cementation’s requirements. Most critically, the Cementation team proposed reducing the size of the jaws from about 70 centimetres to about 45 centimetres. That “would reduce the stress on the boom and hopefully reduce or eliminate bending of the extendable booms, failure of the extendable booms and cracking of the jaws,” Gough said.

VSM 14 design From this process emerged the VSM 14. This machine has 45-centimetre jaws and the booms are made of higher-strength steel that can resist bending and breaking. The extendible boom tube was redesigned to have a constant cross section in the failure-prone area, thus eliminating the stress caused by the change in wall thickness. A new centre pipe design eliminates failures, a new jaw cylinder shroud prevents the buildup of debris and new leather cylinder packings are more tolerant of contamination in the air. The VSM 14 also has an additional 24 inches of reach, which Gough explained is useful for two reasons: it can be used in larger-diameter shafts, and it can allow the boom to


upfront UNDERGROUND MINING Shaft muckers have evolved over the last six decades and the latest designs are far more reliable.

Courtesy of Joy Global

operate less than fully extended, which reduces likelihood of damage. Two complete machines and two spare boom assemblies were delivered in spring 2007 and tested in the Inco (now Vale) Coleman exhaust shaft sinking project, which involved sinking a 21-foot diameter shaft to a depth of 4,371 feet. The machines performed beyond expectations. “We did not have a single bent boom or boom failure,” said Gough. “Downtime on the machines was limited to the same operator-induced problems that accompany all of the various vertical shaft muckers, broken hoses and jaws cylinders damaged due to contact with the shaft wall.” Despite the reduced jaw size, the actual mucking capacity of the VSM 14 was unchanged. Studies showed that the larger jaws were only half-full on average, so their size could be reduced while maintaining a capacity that would not affect production cycle times. Cementation’s cost data proved that the new VSM had paid off. At the Coleman exhaust shaft, where the VSM 14 was first used, all items charged to the shaft mucker’s cost code totalled $204,507.95, which breaks down to $181.30 per metre or $1.30 per tonne. In contrast, the costs attributed to the mucker at the Nickel Rim vent shaft came to $460.50 per metre and $3.80 per tonne. The Nickel Rim main shaft had a cost per metre of $769.16 and a cost per tonne of $4.78. These figures include parts and rebuilds, but not labour or downtime losses. The new design has become the standard shaft mucker for Cementation and has found other customers. MTI/Joy Global has sold 22 of the machines since they were developed. They have been used on shaft-sinking projects at the Resolution Copper mine in Arizona and the Lucky Friday mine in Idaho. CIM

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New study gives greater insight into the impact of corrosion on support systems

Courtesy of John Hadjigeorgiou

Cracking down on corrosion

The effects of corrosion on underground support systems has not been well understood until now.

By Kelsey Rolfe

hen support systems at underground mines start to experience corrosion, they begin a process of degradation that, depending on a mine’s environment, can span years or can happen breathtakingly quickly. With enough corrosion-instigated degradation, the support systems lose their ability to do their job, which results in falls of ground that can have disastrous economic and safety consequences for the mines. “You’re losing access to the excavation, so you have to go back and install support again,” said John Hadjigeorgiou, a University of Toronto professor and the Pierre Lassonde Chair in Mining Engineering. “You’re losing money due to installing support, but also due to loss of production.” Falls of ground, he added, can also put workers in danger. Hadjigeorgiou has studied the effects of corrosion on underground reinforcement and support systems for more than 15 years, often being called in after sites experience falls of ground to help miners determine what went wrong. “Over the years what I became interested in was trying to be more proactive, trying to understand the fundamentals of corrosion and how we can mitigate it,” he said. His most recent publication in CIM Journal (Vol.6, No.3) was co-authored by Jean-Francois Dorion, formerly a PhD candidate at Université Laval and now chief engineer at Nyrstar’s Langlois mine, and Edward Ghali, a professor at Université Laval. They revealed the results of five years of research at seven underground mines in Canada. The study gives greater insight into the loss of capacity in underground support systems due to corrosion, building on Hadjigeorgiou’s previous published work, and the resulting guidelines have been adopted at several mine sites. Corrosion in mine sites is born out of the surrounding environment, with warmer temperatures, humidity, water, acidity, conductivity and the presence of different minerals in the ore body all playing a role. Atmospheric and aqueous corrosivity varies between sites and even between two points at the same site. An underground mine’s corrosivity ultimately affects how long support systems can safely operate before they begin to degrade or, worse, fail. Sites can experience two types of corrosion: uniform, which the study focused on, or non-uniform (also known as local-

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36 | CIM Magazine | Vol. 10, No. 6

ized). Both, Hadjigeorgiou said, can be equally problematic. A support system experiencing uniform corrosion will see the same level of corrosion across its surface. Localized corrosion is contained to specific areas, and often looks like pitting.

Filling a void Corrosion itself is a widely studied topic, but its effect on hard rock mining support systems is not a well-covered area. According to Hadjigeorgiou’s study, there have been efforts made in the past to develop classification systems to determine how susceptible to corrosion an environment is, but “for a variety of reasons, these classification systems have not gained widespread acceptance.” Hadjigeorgiou and his collaborators are attempting to fill the void. The long-term objectives of their research are to have enough data and understanding to allow miners to choose better support strategies at their sites and to create a reliable assessment of the expected life of support systems. The research was conducted at the LaRonde, Mouska, Doyon-Westwood, Niobec, Persévérance and Géant-Dormant mines as well as through laboratory work. Corrosion coupons – small metal sheets – were installed at locations throughout the participating sites and checked at three-, six- and 12month intervals to analyze the level of corrosion and test for any loss in capacity. The co-authors also tested mesh and bolts. The results of the coupon tests showed a “strong negative linear relationship” between a coupon’s tensile strength and the uniform corrosion rate: as the coupons spent more time exposed to a corrosive environment, their strength notably decreased. This finding expanded on Hadjigeorgiou, Dorion and Ghali’s previous research, and further cemented the link between corrosion and support system capacity. While the results seem common-sense, sites still struggle to determine the length of time their reinforcements will last and whether it is worth the extra cost to install more corrosion-resistant support. The study also addressed the efficacy of galvanization and special coatings as corrosion deterrents, finding that galvanized coupons were “consistently more resistant to corrosion” after 12 months of underground exposure. John Henning, Goldcorp’s director of geotechnical engineering, said he has seen the benefits of galvanized coatings at


N e


the company’s Red Lake mine in northern Ontario, which Hadjigeorgiou audited to determine corrosion levels at a new zone in development. “If you want [the support] there for a long, long time you do a galvanized coating,” he said, though he noted it costs a bit more than support elements without additional protection. If the support was not needed for the long term and “depending on the other conditions at the site, you’d probably go with regular support,” he said.

Visual guides What emerged from the research was what Hadjigeorgiou called a “series of design charts” for assessing corrosion within mine sites, which are essentially visual guides for miners looking to understand what level of corrosion their sites are experiencing and how it changed over time. The guidelines, Hadjigeorgiou said, can help miners better identify when corrosion is becoming a safety or economic risk to the site. “[Miners are] putting in the support and expecting it to last for the working life. They don’t want it to be a perishable thing,” he said. “[But] out of our research, and now the guidelines in the paper, we are telling them, you’re getting these signs, you might think to intervene either for rehabilitation or to replace the support.” One such chart contains pictures indicating six different levels of atmospheric and aqueous corrosion, starting with “no or very little corrosion,” a level which occupies less than 10 per cent of the surface, up to “extreme corrosion,” a level under

38 | CIM Magazine | Vol. 10, No. 6

which the support is easily breakable. Miners can use the photos to contrast with their own support system to determine, roughly, the level of corrosion and the risk of collapse. “These guidelines are already being taken into consideration by mines that have identified corrosion support as an important ground control problem,” said Hadjigeorgiou.

Early adopters One early adopter of the guidelines is Agnico Eagle’s LaRonde mine, which is located between Rouyn-Noranda and Val D’Or, Quebec, and also served as one of the study’s test sites. The co-authors approached Pascal Turcotte, LaRonde’s assistant superintendent of engineering, in 2008 with a request to measure corrosion rates in different environments. “With the temperature in our excavations and the type of ore body – massive sulphide – [LaRonde] was a good case study,” Turcotte said, “for [them] and for us also, to measure our corrosion.” LaRonde experiences the worst corrosion in its exhaust system, Turcotte said, because the high temperature increases the corrosion rate of the ground support in that area. Sulphide in the ore body and the humidity at the site also play a role. Turcotte said the study and the guidelines have led to a change in how corrosion is handled at LaRonde. “With this study we are less tolerant with the corrosion on site,” he said. “So, it is safer for our employees and there is less risk of having [screen damage] caused by corrosion of the ground support.” CIM


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Come hell or high water The fight to sink the deepest single lift shaft in the United States

Pockets of water inflows were encountered between 1,770 metres and 1,969 metres below surface, but cumulative flows never exceeded 250 litres per minute until the shaft was sunk deeper. A pump level cooling station was installed 1,396 below surface.

By Michael Yang

Resolution Copper’s shaft 10 is the deepest single lift shaft in the United States with a final depth of 2,116.2 metres.

Photos courtesy of Cementation

tough group of miners finally reached the planned bottom of Resolution Copper’s no. 10 exploration shaft in Arizona’s Copper Triangle – 2,116 metres below the surface – in mid-November last year. It had taken over five years of hard work and creative engineering in very hot, wet conditions to sink America’s deepest single lift shaft. The record-breaking shaft is the first of six deep shafts that are required in order for Resolution Copper to access one of the largest undeveloped copper deposits in the world. The ore body, seated over two kilometres underground, below the historic Magma mine near Superior, has an Inferred Resource of 1.7 billion tonnes with a 1.52 per cent copper grade. Resolution Copper, a subsidiary of Rio Tinto, plans on mining the porphyry deposit using an enormous panel block caving operation that will produce up to 120,000 tonnes per day of ore during full production. Shaft sinking officially started in January 2009 with Cementation USA as the contractor. The production cycle called for three-metre rounds and six-metre liner sets, and involved drilling concentric holes, loading, blasting, mucking and then installing ground support, concrete lining and utilities. A double-drum hoist and two 14-ton sinking buckets moved all the materials and equipment up and down the shaft, and an innovative personnel bucket was used to move people. “We had an overall set-up that was designed to accomplish each of these cycles efficiently,” said Tom Goodell, general manager of shaft development for Resolution Copper, in a presentation last year. “The key to it is the Galloway work stage.” The Galloway is a 160-ton work stage that has virtually every necessary piece of equipment embedded within its five decks: four pneumatically powered jumbo drilling machines,

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40 | CIM Magazine | Vol. 10, No. 6

two vertical shaft muckers, concrete forms for the shaft liner and support tools for utilities. Always remaining near the bottom of the shaft, the stage allowed the miners to complete cycles extremely quickly and work with high levels of automation as the drills and muckers could be operated with an onboard control console. “During our peak times, we were completing a full cycle per day,” recalled Matthew Swanson, Cementation’s lead engineer on the project. “Everything was moving along very well. Then we hit the hot water.”

In the deep end Initially, the shaft was expected to encounter minimal water inflows throughout its sinking and very little past 1,200 metres deep. This information was based on the limited data from a single core hole, but “it was generally accepted that this was an exploration project: a large diameter shaft to be sunk to depths beyond what had ever been accomplished in the region,” said Swanson. As such, the existing shaft recovery dewatering system was designed to handle up to 750 litres per minute (L/min) of clean water in the event unexpected water was encountered. During sinking, however, dewatering relied entirely on the hoist to bail the water using the sinking buckets. The sinking refrigeration system was sized based on the expected heat load from the rock mass, no significant heat load from water was expected. So when hot water, at 80 C, began to flow out of probe holes drilled on the 1,969-metre bench at 500 L/min, everyone was alarmed. Within the next 50 metres, the inflows reached 1,700 L/min, regularly flooding the shaft bottom and bringing air temperatures as high as 45 C with 90 per cent to 100 per cent humidity.


Standard-setting shaft mucking

With the Joy vertical shaft mucker (VSM-14), the process for removing muck is now more reliable and cost efficient. Key design features of the VSM-14 include: half-yard jaws; an additional 24 inches of reach; high-quality steel booms; reduced debris buildup and a new center pipe design. Achieving a lower cost per ton and higher mean time between failures compared to competitor mucker models, the Joy VSM-14 is setting a new standard for the industry.

JoyGlobal.com Joy Global and Joy are trademarks of Joy Global Inc. or one of its affiliates. Š 2015 Joy Global Inc. or one of its affiliates.


Courtesy of Cementation

station was developed at the 1,987-metre level: a three-metre ring station with two positive displacement pumps that could handle up to 1,150 L/min each of dirty water. Submersible pumps fed groundwater up to this station bottom via existing steel pipes embedded in the shaft liner. The water was then moved up to an existing, permanent pump station at the 1,731-metre level used for dewatering of the old Magma Mine workings. “That became the primary dewatering system while the rest of the staged pumping system became our contingency plan,” said Swanson. To deal with the heat load in the shaft, which had reached 6.61 megawatts and more than doubled the existing cooling capacity, Resolution Copper decided to finish construction and comPressure grouting campaigns with both cementatious and polyurethane grouts were largely unsuccessful and, after three months, it was decided the ground was ungroutable. missioning of a planned, permanent cooling plant on the surface much earlier than anticipated. As part of these upgrades, Cementation “It wasn’t just handling the water that gave us problems,” retrofitted 610 metres of two-metre-diameter exhaust duct said Swanson. The heat and humidity had risen to levels between the shaft bottom and the main 1,396-metre pump deemed potentially hazardous to work in under both Rio level. They also installed six giant 5,900-kg cooling coils and Tinto’s and Cementation’s safety standards. “We had to estab- five 186 kW fans. lish cool rooms on the Galloway and in the stations,” he Another challenge arose just as the shaft resumed sinking in recalled. These rooms, in conjunction with strict work-rest the summer of 2014 with all systems online. “Fog was forming regimes, helped mitigate some of the risk associated with the at the shaft bottom where all of the cold air was interfacing heat and humidity. with the hot, humid air,” said Swanson. The visibility would After multiple pressure grouting campaigns did not suffi- be reduced to the point that it forced work stoppages at times. ciently reduce water inflow, adjustments had to be made to Controlling the fog involved continuously varying activities continue sinking under the new conditions. A temporary, to keep it in check, rather than a static solution. “It was really makeshift shaft-bottom dewatering system was installed using just a big balancing act where we sometimes reduced the coolexisting infrastructure. The sinking method was modified so ing, sometimes limited use of the compressed air equipment, that only half a bench was taken per round. This was a large and so on to mitigate the formation of the fog,” said Swanson. improvement to safety and production, as the lower side could “But it got us down to the bottom of the shaft.” act as a sump for the water while work took place on the dry, Many of the miners, most locally hired and trained, had higher ground. However, installation of shaft services or the stuck through the project since it began with collar construcconcrete liner required the work stage to be moved away from tion in 2007. For them, completing the gargantuan task is just the shaft bottom, temporarily halting shaft-bottom dewater- the first of six steps in building Resolution Copper’s massive ing. This would result in the bench flooding and require hours underground operation. of dewatering before sinking activities could resume. High lev“The work that we did didn’t always involve typical, by-theels of solids in the water were generated by the sinking cycle, book solutions,” said Swanson. “That’s why it was coined brute and this led to further difficulties with dewatering, negatively force engineering. It was a fight – sometimes ugly with lots of affecting pump performance and reliability. hard work – but we got it done, and now there is a blueprint As sinking progressed, it became apparent that additional for the future.” CIM controls were needed to continue sinking safely and efficiently. Sinking was eventually paused in September 2013 after progress had stalled out to less than half a metre per day. “If you had asked me five years ago if we could sink a shaft with that much water coming into it, I would have said ‘No way,’” said Goodell.

Permanent mitigation measures In the months that followed, work moved to focus on the installation of upgraded cooling and dewatering systems to support the completion of the project. An additional pump 42 | CIM Magazine | Vol. 10, No. 6


Need for speed Can existing technologies deliver big gains?

Courtesy of Alex Henderson

By Peter Braul

lex Henderson wants to radically change how underground mines operate. But, says the Sudbury-based consultant, dramatic improvements do not necessarily need to be expensive and risky. Based on his extensive experience in Ontario’s biggest mines – he worked for Falconbridge and Xstrata in the early 2000s and for Vale for more than nine years – he said he believes a step change in productivity can be accomplished using existing proven technology. As general manager of underground mining technology at Vale, Henderson had the chance to prove out concepts such as Rail-Veyor, a type of remotely operated railcar first developed in the 1960s and used to transport ore and waste. Henderson gained rare real-world experience with this and other alternative technologies, and today he hopes to help operations make the leap to commercialization and improved profitability.

A

CIM: You stepped away from Vale in 2013. What did you take away from your time there? AH: Around 2010, as general manager of mine and mills technical services for the base metals North Atlantic operations, I put together an outline for a two-year project, worth roughly $50 million, to demonstrate components of high-speed development and production. And the core to that was the RailVeyor – figuring out how we could integrate Rail-Veyor into the development process such that we could achieve 400 feet per week or 17 metres per day, where traditionally we would get maybe 600 or 800 feet per month per crew. At the production stage, where current operations would get about 1,000 tonnes per day from a stope, we came up with plans on how to achieve over 3,000 tonnes per day. I knew there were risks associated with doing that, because typically if the economy does slow 44 | CIM Magazine | Vol. 10, No. 6

down, then research and development is one of the first areas to get hit. At the same time I was pretty excited with the opportunity, and it was pretty obvious that they were very committed to seeing significant change as funding for the project was supported at senior levels in the organization. CIM: You recently published three white papers on underground mining practices. What message did you want to get across? AH: It starts with the idea that technologies already exist today to cause a step change in underground hard rock mining, but we haven’t re-engineered our mining processes or redesigned our mines to use that technology in the most efficient manner. I put together what I call a five-step process to implement step change technology. And that is based on what went well, what didn’t go so well at Vale, and what some of the key components are that have to be in play in order for a company to implement step change technology. Because, although we had demonstrated it, we hadn’t commercialized it, and that was where I would say the project failed. CIM: Was that failure a matter of a time, funding or something else? AH: The first step in my five-step process is you have to have a compelling reason to change and this needs to come from senior people in the organization. When the project started, senior officials in charge of the base metals operations clearly understood the compelling reasons why the base metals needed to have a step change. With changes in personnel there was a breakdown in communication and the reasons why I was doing what I was doing.


upfront UNDERGROUND MINING

But it wasn’t just one thing. Various factors caused the project to be discontinued, including the drop in metal prices. These are all key learnings that I’ve built in to the five-step process.But it wasn’t just one thing. Various factors caused the project to be discontinued, including the drop in metal prices and the change in senior leadership at Vale. These are all key learnings that I’ve built in to the five-step process.

CIM: You say we need to re-engineer our processes. Is that something you can see applying to existing operations? AH: The process is very applicable to existing operations. At the 114, it became very apparent to me that we needed to put together a plan for how we transform our existing operations and begin to adopt the technology. Even with Dundee and the Bulgarian operations it’s more about transforming existing operations, rather than trying to come in with completely new technology. It has to be appropriate technology for the capability of the operation.

CIM: How has the mining industry reacted to your ideas? AH: Initially, when I started my consulting business in 2014, I focused on junior mining companies because I thought they were more entrepreneurial and able to make decisions CIM: What technology already exists that we are not using in the quicker. I talked to a lot of junior mining companies and best possible way? what I seemed to constantly run into was, “Well, we really AH: The concept the Rail-Veyor is based on was developed like your ideas, Alex, but we need to borrow money. And in by the French in 1965. So it’s technology that has been order for us to borrow money we have to have a proven around for a long time. A scooptram can move material at bankable, feasibility study meeting the NI 43-101 80 to 100 tonnes per hour, whereas a continuous loader requirements. And although your technology is proven, like the Häggloader or Schaeff loader can move material at some of these process changes in mining methods aren’t 350 to 400 tonnes per hour. Historically, these loaders were [proven]. So we don’t see how we can raise capital if we are pieces of equipment that were used for development proposing significant change.” purposes and people would say to me, “Well, how can you Last fall, I completely changed my approach. I went out to use a Häggloader in an open stope?” You can’t. You have to the majority of the mining consultants and said, “If you have redesign the way you mine the stope in order for you to get a company struggling to make its project economical and it the full benefits of the Häggloader. We can’t force existing wants to take a look at how technology could change that, I technology on our existing processes. We’ve got to rewould be open to working with you.” I also focused more on engineer our processes and re-design our mines in order to mid-size to larger mining companies and put a lot more use that technology in the most efficient manner. CIM emphasis on the five-step process rather than the technology. That began to open things up, but I would say definitely that the company that’s been the most aggressive all along is Dundee Precious Metals. Dundee visited Vale’s 114 ore body demonstration plant when we were demonstrating what could be done. And one of the comments that vice-president of operations David Rae made was, “We came up expecting to see a With offices in Toronto and Vancouver and a number of material handling system (Rail-Veyor), but Spanish-speaking consultants, AMC is perfectly placed we saw a total new way of mining.” The to assist clients with projects in the Americas. Rail-Veyor there is only a tool. I started the five-step process at Dundee’s Bulgarian operations in the early part of this year. Consultancy assignments in

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CIM: Are other companies starting to come around? AH: I think in terms of where the mining industry is and where things are in general with the sustained lower metal prices, people are becoming much more aware that it’s not just cost cutting and capital avoidance that’s going to allow companies to stay prosperous through this process. Rather, it’s their ability to adapt to new technology and make sustainable changes to their operations.

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October/Octobre 2015 | 45


Field of vision

ORE GRADE

s

2%

1%

0%


How supersensitive machines can stop you from processing waste By Ian Ewing

“On average across the mining industry, 44 per

cent of the total electricity consumption is

dedicated to crushing and milling activities,” reads the first paragraph of a 2014 study published

in the journal Minerals Engineering. But how much

of the material that is crushed and milled actually

contains anything of value? Industry-wide, as

much as 30 to 60 per cent of processed material

Ore sorting technology promises to deliver a more uniform feed to the mill.

Photo editing: Elissa Ebersold, original photograph courtesy of Copper Mountain.

contains no ore.

Miners have found that they are able to drastically reduce energy expense and improve economics by using advanced sensing technology to weed out waste – a concept known as ore sorting. Joe Lessard, a project engineer with Orchard Material Technology and lead author of the study, is one of a growing number of industry insiders who believe that ore sorting will deliver major changes to the way miners use energy. “There are no technologies that have the potential to actually upgrade the material to such an extent as ore sorting does, and with so little input cost,” said Lessard. “The economic payback is so fantastic and so rapid that it’s worthy of a feasibility study, it’s worthy of the pilot-scale implementation, and then the scale-up to full-scale production.” October/Octobre 2015 | 47


The diamond and uranium sectors use the technology fairly extensively. But for most minerals, automated ore sorting has never achieved widespread acceptance, despite first entering commercial service in mining as early as the 1960s. The first generation of automated sorters earned a poor reputation due to low sensing resolution, poor discrimination, high capital costs and, most problematic, low material throughput. The technology was largely abandoned in mining before it ever really got started. Sorting technology has chugged along since it was first introduced, slowly maturing and eventually finding widespread application in the food processing, recycling and scrap metal industries. Today, better sensors and increased computing power have helped make the technology more effective. And the changing economics of the mining industry have finally convinced mining executives to open the door when Lessard and others drop by to talk about this previously spurned technology.

existing operations worldwide, a scarcity of high-quality new discoveries, cost inflation driven by high input costs like energy, and prices that aren’t high enough to support the current cost of doing business in mining.” According to Bamber, ore sorting is the natural remedy: “Mines in general, whether open pit or underground, are including a tremendous amount of waste material in what they call ‘ore.’ If you can eliminate that material, you can improve the basic economics of mining across the board.”

Currently sortable minerals: Barite Calcite Coal Copper porphyry Copper-gold Diamond Gold (by association) Iron Lead Limestone Molybdenum

Nickel Nickel sulphides Nickel-copper Phosphates Platinum Potash Rare earths Refractory metals Talc Tungsten Uranium Zinc

Fundamental principles

Sensing technologies currently in use, and what they are commonly used for:

Economic sense

48 | CIM Magazine | Vol. 10, No. 6

Photo editing: Elissa Ebersold, original photograph courtesy of Copper Mountain.

Modern ore sorters are available with many sensing technologies and sorting mechanisms, but the fundamental principle is similar in each: by sensing the composition of a volume of material or of individual rocks, waste material with little economic value can be identified and separated from valuable ore before too much money is spent processing it. “Three or four years ago, when we The traditional format is a beltreally started getting into the mining based machine that sits ahead of industry, we truly had to push for the grinding and milling circuits, those meetings,” said Jason Looman. analyzing – in nanoseconds – As president of Steinert US, a leading crushed and pre-sized run-ofmanufacturer of sorting machines, mine material as it travels along a Looman has seen a major uptick in conveyor. A tenth of a second interest since then. “Now, rather than later, based on the composition of us calling them, the engineering the individual rocks on the belt, an Sources: Joe Lessard, Andrew Bamber, Arvin Mazhary, Darren Koningen, Jason Looman, Chris Rule houses and the end users are calling array of pressurized air nozzles us and asking us to come out and talk to them about the tech- diverts the waste material and ore into separate chutes as nology, what it can and can’t do,” he remarked. “Even in the the rocks sail off the end of the belt. The cutoff grade is determined through feasibility studies prior to implemenlast six months, we’ve seen a big shift.” It is easy to see why. The industry is facing structural chal- tation but can be easily recalibrated as mine plans and ecolenges that current mining methods simply are not coping nomics change. Lessard, whose study examined the economics of ore sortwith. “The price points are starting to make sense for sorting,” ing, pointed out that with adequately heterogeneous minerexplained Lessard. “The cost of electricity, the cost of water, and the cost of other utilities in the process all of a sudden alization, diverting just a small percentage of waste rock point to a need for more efficient technology solutions. We provides significant value. In one case study he ran, spending can no longer just grind, grind, grind, because the cost of elec- $9.6 million to purchase and install a pilot-scale sorter on a tricity is too high.” side circuit quickly paid off, generating between $7 and Andrew Bamber, CEO of Vancouver-based sorting start-up $9 million in added revenue annually. “Even with what we MineSense, sees even more behind the trend. “It’s a perfect would consider to be a crummy sorter – a sorter that is only storm for a margin-enhancing technology right now,” he rejecting 30 per cent of the feed as waste – you would still explained. “You’ve got a combination of declining grades at make all your money back in less than two years,” he said. Electromagnetic (certain base metals) Magnetic (anything with magnetic properties) Near-infrared (NIR) (industrial minerals including calcite) Optical (anything with distinction in visual features, especially by colour) Radiometry (radioactive materials, especially uranium) Ultraviolet (UV) X-ray fluorescence (XRF) (surface sensing) X-ray luminescence (XRL) (surface sensing, for diamonds) X-ray transmission (XRT) (probably most versatile: best for base metals; for bulk-sensing, anything with different atomic densities)


Photo editing: Elissa Ebersold

Preventing waste material from making its way into the mill would reduce operating expenses and capital expenses.

“It was surprising, even to us, to run the numbers and see just how profitable it actually would be.” One company betting those economics will pan out is Minera Alamos. The junior miner recently had to revisit the mine plan for its Los Verdes copper-molybdenum project in Sonora, Mexico. “The hang-up in the area is that there are no existing milling facilities nearby,” said company president Darren Koningen. But by using an X-ray transmission (XRT) sorter to pre-concentrate the ore, hauling to a more distant mill has become economically viable. “Instead of changing the mine plan so that we’re only classifying ore that’s more than, say, one per cent copper, and then losing all the sub-grade or mid-grade material,” Koningen explained, “by putting the sorting equipment in place we can mine almost everything, and we’ll use the sorter to reject all the crushed rock that’s less than 0.5 per cent. We’re looking at getting double the grade or more, while keeping our recoveries in the 90 per cent range. And it’s 90 per cent of a bigger starting pool, because we’re now mining more material – all that material between 0.5 per cent and 1.0 per cent that normally we would have thrown in the waste pile.

The earlier, the better Reducing the quantity of material directly ahead of comminution can create enormous energy (and cost) savings, but MineSense’s Bamber prefers to intervene even earlier in the flowsheet. “In ShovelSense (MineSense’s flagship product), we’ve developed a particularly transformational technology that allows mine operators to measure, report and decide about the grade of material in bulk at the point of extraction,” he said. By outfitting the shovels and loaders themselves with all the necessary sensors and processors, operators can route ore for processing or to the waste dump immediately upon

extraction, before undergoing any hauling or processing whatsoever. “In the time it takes a scoop underground to take a load of material from the stope or a shovel to load material from the bench, we can take a bulk measurement, report the value and compare it to the expected value,” he touted. Current field trials show that his sorters confirm the existing mine data around 70 per cent of the time. But the remaining 30 per cent of material – which would otherwise be misclassified and misdirected – represents an enormous loss of value (when ore is classified as waste) and increased cost (when waste is processed as ore). At one operation that MineSense has analyzed, a 50 per cent improvement to the current grade control and ore routing process would add $370 million to the net present value of the mine. As an added benefit, Bamber said, real-time point-ofextraction sensing and classification can help improve the short-range mine plan as data is collected with every bucket load and transmitted wirelessly to production management systems. “Bulk sorting, the way we envision it based on shovel-based systems or bulk belt-based systems, directly enhances ore body modelling, block modelling, short-range processes and mine planning,” he said.

End-to-end process improvements What the different philosophies and techniques all have in common is a capability to mine more material at lower grades, reject significant quantities of worthless material and pre-concentrate the crushed material before it gets processed. In addition to using less electricity per ounce, pound or tonne of recovered metal, ore sorting also decreases usage of consumables like water and reagents. A byproduct of pre-concentration is a more uniform feed head grade, making October/Octobre 2015 | 49


Photo editing: Elissa Ebersold

Heterogeneous deposits can derive the most benefit from ore sorting.

downstream operations easier to manage and often improving recovery rates, explained Lessard. In the case of new plants, capital savings can be realized because a smaller plant is adequate for the lower volume of material, while retrofitting

existing plants with sorting technology can result in decreased operating costs by taking unneeded units offline. And with less material getting milled into fines, tailings ponds can be smaller, mine lives may be extended and the ultimate environmental impact of an operation may be decreased. There are other ancillary benefits too: pre-concentration can increase the economically viable resource, increasing mine valuation. The operator can easily alter production capacity and cutoff grades in order to meet market demands. And it can provide a new revenue stream, as the new waste stream from the sorters can be sold as aggregate.

The challenge of scale The gains made with sorting technology are significant, but a few niggles and considerations remain. The heterogeneity of a deposit affects the usefulness of any sorter. “If the ore is widely and evenly dispersed so that every rock that comes out has roughly the same amount of the mineral of interest, sorting won’t be helpful. What would you reject?” Lessard asked rhetorically. “But that’s uncommon, over entire ore bodies. Anywhere there is clear mineralization, clear partitioning, ore sorting can have great value.” Knowing whether a mineral can be identified by sorting sensors is another problem – there are not yet any publicly available tables to determine which sensor technology to use for which mineral. But, said Lessard, “you should always do a feasibility or amenability study to test whether or not the ore will respond. You might dismiss sorting early because an ore won’t work with XRT, but maybe it’s a great candidate for Xray fluorescence (XRF) or optical sorting. And until you try them, you can’t really say definitively whether or not a sensing technology will work.” Meanwhile, the list of ores that have

50 | CIM Magazine | Vol. 10, No. 6


been successfully sorted grows constantly as manufacturers perform amenability studies with new sensing technologies, improved sensors and better algorithms on faster computers. Even minerals that cannot be sensed directly may be sortable, according to Steinert’s Looman, if they are associated in the ore with a more amenable “tracer” mineral. Gold, which can be found by its association with quartz or with other metals, is one such example. The longstanding complaint about throughputs has not been entirely solved yet, though. Throughputs are now in the range of 100-200 tonnes per hour per machine, an order of magnitude greater than just a decade ago. For large mines in some sectors, it is still not enough. “This technology isn’t going to do 1,000 tonnes per hour from one unit,” admitted Looman. “But you can create a circuit with the right number of units that would, and it can still be more economical than a plant without them.” Many mines might see value just by adding a sorter to a smaller-capacity side circuit, too. Anglo American Platinum (AAP) is one operator that has added “the right number” of units. Chris Rule, the head of concentrator technology for AAP, has overseen the construction of a US$5-million four-sorter proof-of-concept plant at Anglo’s existing Mogalakwena North concentrator facility in Limpopo Province, South Africa. Three years of pilot work with a single sorter at another facility in Johannesburg led to the new 25,000-tonne-per-month plant being built. It uses XRF to sense copper and nickel as a proxy for platinum-group metals (PGM). “Ore upgrading has been a strategic need for a number of years for AAP, and indeed for the [entire] PGM industry,” Rule said. “The desire to produce fewer tonnes for more ounces is economically persuasive, especially in the face of lower grades and more difficult-to-process ores, above-average inflation, rising energy costs and productivity challenges here in South Africa.” Several months on, Rule added, the technology has shown the same value-creating results as the pilot tests.

A new order of sorters “A lot of the problems with older sorters were engineering problems, not theoretical limits,” concluded Lessard. “And inevitably, those technological limitations were worked through.” No one sorter is going to be effective at every mine site. But after performing amenability tests, and the field trials that manufacturers are often happy to do to prove their products’ capabilities, a relatively simple economic analysis can determine if sorting is worth it. “I really think sorting will become much more common,” predicted Minera Alamos’ Koningen. “It has the potential to impact both capital and operating costs, and I can’t imagine these days that that’s not what everybody is trying to do.” “Of any market I’m in, ore sorting has the highest growth potential,” added Steinert’s Looman. “I think it’s on the edge of acceptance, especially based on the number of inquiries we’re getting from the large engineering companies. Now, when the markets are down, is when you really have to find all the efficiencies you can. This is a way to do that.” CIM

October/Octobre 2015 | 51


Image courtesy of Palabora Copper

The team at Palabora opted for raise boring to develop its vent shafts. The raise borer features a system that allows shaft support to be installed remotely.

HARD LESSONS BY MICHAEL YANG

When Palabora Mining Company (PMC) decided to transition its giant open-pit mine underground nearly 15 years ago, the South African copper producer took on a formidable challenge: to build a massive block cave in one of Africa’s hardest rock formations. The resulting Lift I operation set industry benchmarks in both secondary breaking and integrated design, but it was not without its growing pains. Now, as PMC develops its bigger and deeper Lift II expansion, it is drawing on lessons from the past and new technologies to ensure the $1-billion project is a success. 52 | CIM Magazine | Vol. 10, No. 6

n paper, block caving is simple enough. Crosscuts beneath an ore body force the rock to progressively collapse on itself, forming an artificial cavern from which the rubble flows downwards into a system of pre-constructed funnels and tunnels. “Think of it as an inverted open-pit mine capable of mining the same types of massive ore bodies,” said Nick Fouche, PMC’s general manager of growth. For a company with a half-century of experience operating its former 82,000-tonne-per-day openpit mine – the largest in South Africa – the transition into an underground equivalent was expected to be easy enough. Experience soon taught them that block caving is anything but. “Although we had some of the best block cave expertise in the industry we were in new territory, and there were many unknowns as the company began developing the Lift I operation 15 years ago,” said Fouche. “We didn’t always have the right equipment, processes and experience, and it wasn’t until we addressed those that the operation became a success.” Currently, PMC is the only copper producer in South Africa, supplying nearly 80 per cent of the refined metal in the local market. After its open-pit operation in the Limpopo province ended in the late-90s, the company became one of the first in the world to directly transition from an open-pit to a block cave, setting industry precedents with an eventual volume of 30,000 tonnes per day (t/d) and a central cave height of 450 metres. However, while Lift I began drawing ore in 2001, it would take four to five years for the operation to ramp up to full production due to problems dealing with the fragmentation of the rock. A lack of extensive cave monitoring has also meant that the prediction of the ore grade could not always be forecasted accurately. This, along with the North Wall subsidence, meant that the mine would reduce its life much faster than originally expected, shortening the mine life to the end of 2015 rather than 2023. “Given the situation, we began looking at the possibility of a second block caving expansion, 450 metres directly below Lift I, in November 2011,” said Fouche. A study based on 72,000 m of core drilling data concluded that the deeper ore body is very similar in size, shape and grade to Lift I, at 0.64 per cent copper, so it can be economically mined using the same method. With a planned volume of 33,500 t/d and a production level 1,650 m under the surface, Lift II will be one of the largest and deepest block cave mines in the world when the first ore is drawn in late-2017. “We’ve done everything we could to ensure that the expansion will be a success from the get-go,” said Fouche. Beneath the tall shrubs and grassy plains of Limpopo’s famous Bushveld lies some of the most mineral-rich deposits in Africa, in some of the continent’s hardest rock complexes. PMC’s mining operations sit on an apatite-rich pyroxenite formation in the northeastern region of the province – only the Bushveld igneous complex has more competent rock in the region. “The issues associated with ramping up Lift I was very wellknown in the industry, and it had to do with the fragmentation sizing of the rocks coming through the drawpoints,” said

O


PA L A B O R A

Hans-Dieter Paetzold, Palabora’s chief geologist. “We were expecting much greater fragmentation than what actually occurred because the rock is so strong.” Production maxed out at 20,000 t/d due to the bottlenecks in the drawbells and the crushers from oversized boulders. Eventually, the business deployed an internal team of mining and processing experts to design a secondary breaking process with the appropriate equipment to manage the ramp up in a much more orderly and predictable manner. It took nearly two additional years for the operation to reach full production but when it did, Lift I had “one of the best secondary breaking systems in the world,” according to Fouche. For Lift II, instead of staying in the same four-crusher configuration, each with only one tipping point, PMC is planning on using two larger 2,000 t/h ThyssenKrupp BK 63-75 gyratory crushers. The crushers have larger throat sizes that allow them to handle larger ore and four tipping points per crusher, enabling the load-haul-dumps (LHDs) to tip from a total of eight different tipping points. The two-crusher configuration also enables the potential use of electric LHDs, due to the shorter distances between the crosscuts and the centrally located tipping points. “Using electric LHDs is one of the ways we can control the high heat down there,” explained Paetzold. Virgin rock temperatures at Lift II’s depth are expected to reach 58 degrees Celsius and

| project profile

designing an electric vehicle footprint for the cave is crucial in significantly reducing the overall heat load. The project team is still weighing the advantages of the cooler electric LHD against the greater flexibility of untethered diesel machines, or battery-powered units that require charging stations.

Second guess While Lift I’s secondary breaking configuration eventually became an industry benchmark for breaking extremely competent ore, the operation’s cave monitoring systems never achieved similar success. “We didn’t have an extensive cave propagation monitoring program in place from the start,” said Paetzold. “We had a few monitoring tools and draw bell sampling, but essentially after eight years it became difficult to predict how the cave will behave.” With only a few time domain reflectometers (TDRs) in the Lift I ore body, the broad seismic system did not allow for sufficient information to paint a full picture of the cave at any given time. As a result, the north pit wall collapsed in 2004 after the crown pillar of the cave from Lift I broke through at the foot of the open pit north wall. Over 18 months, a failure measuring nearly 800 m by 300 m developed along the wall from the pit bottom. Up to 100 million tonnes of waste rock have diluted the ore in the deposit since then, significantly reducing the grade and shortening the mine life by five years.

October/Octobre 2015 | 53


“We now know the importance of predictive monitoring, and will be putting in an extensive system for Lift II.”

Nick Fouche, PMC’s general manager of growth

Image courtesy of Palabora Copper

– N. Fouche

“We now know the importance of predictive monitoring and are in the process of implementing an extensive system for Lift II,” said Fouche. TDRs and smart markers placed in open holes will be installed to cover the caving area between Lift I and Lift II. The collected data will then be stored and analyzed using GEMS software. In addition, the existing seismic system is being upgraded to establish exactly when the deeper cave will begin to affect operations and infrastructure above.

Early works Though the mine life of the current cave is slated to end in December 2015, production out of the cave will still continue until late-2018 to reduce reserve losses. Because the operating block cave mine is located on top of the Lift II block cave development, the company needed to create a construction strategy to build Lift II without halting the existing operation. That brought about the $220-million early works program in 2011, which involved completing twin decline ramps as well as electrical and ventilation upgrades to power both Lift I and Lift II simultaneously. “We didn’t want any kind of lengthy discontinuity between the two operations because we’ve developed the unique skills and experience necessary for block caving and aim to keep the block cave competency in place for the Lift II operation,” Fouche said. This mindset is evident in the breakneck speed at which construction is progressing and the new technologies and processes Palabora is using to get there. Building twin decline ramps in the constrained underground environment usually means progress maxes out at around seven metres per day (m/d). However, the company worked with contractor Byrnecut to develop a process capable of reaching 10.5 m/d. 54 | CIM Magazine | Vol. 10, No. 6

“Instead of taking two cuts, one on each heading, we actually managed to rotate the headings and get three cuts across the two headings every day,” explained Fouche. The advance rates were also supported by the use of a Sandvik 621 loader, the largest ever to be sent down a 1,200 m shaft and the biggest loader operating underground in Africa. Another piece of technology driving the expansion forward is contractor Master Drilling’s RD8 raise borer. Modelling indicates that the current vent shafts are in danger of collapsing with the propagation of the cave, “and it’s crucial that we get the first new vent shafts in by December 2016, because that’s when the construction level will surpass the current ventilation capabilities,” said Paetzold. The company opted to use the raise boring method over the more conventional blind sinking method to drill the two, 6.1-m diameter vent shafts reaching 1,200 m from the surface down to the Lift I level. The RD8 raise borer is the largest and most advanced drill used in South Africa; with the capacity to bore up to 8.0-m diameter holes 1,500 m deep. The machine uses a combination of electrical and hydraulic power to drive the pistons and engine, and can be operated and monitored remotely by only four people. Data indicate the shafts will intersect geological structures that could present problems during the construction phase when those structures are exposed. However, the RD8 also comes with the contractor’s new Remote Operated Shaft Support (ROSS) unit, developed especially for this project. Instead of waiting for the shaft to be completed and reamed out, the ROSS allows the team to remotely install shaft support up to 1,200 m from the boring unit during the actual drilling process. “If we ever suspect a fallout or failure, we can pause the reaming, hook up the unit, scan the area and then seal it off right away,” said Paetzold. He also noted that building the foundation was a big factor in the decision. A normal blind sinking process usually requires a box cut and the area to be completely dug out until suitable rock to place a foundation on is found. However, the option of piling to support a foundation exists with raiseboring, which significantly reduced the overall construction time. Paetzold said he expects the first shaft, which PMC began work on in March, to be completed by the end of 2016. “Both shafts will be in much faster than if we had decided to sink a single, eight-metre diameter blind sink shaft, and will be three to four times cheaper as well,” he said. The Lift II expansion is expected to extend the mine life until 2033, and this time, the Palabora team is confident that it will get it right from the start. “Block caving truly is a unique skill that must be learned through time and experience,” said Fouche. “And we have been fortunate enough to be given a second opportunity to do it all over again.” CIM


A measure of control

technology

PROCESS MONITORING

By Alexandra Lopez-Pacheco

W

Courtesy of Outotec

Better instruments and a drive for efficiency are making big changes to the way processing plants are run.

Outetec’s PSI particle size analyzers employ laser diffraction technology to measure ore after the grinding circuit.

hen commodity prices were strong and rising, mining companies could afford minor inefficiencies in their plants. That is rarely the case in these days of lower-grade deposits, lower metal prices and economic pressure from every direction. “We have to do better with lower costs,” said Philip Thwaites, manager of process control for XPS Consulting & Testwork Services and a long-time champion for improved process control. “If we’re not efficient, we’re not going to be around. And our industry can be a lot more efficient.” Part of the problem is that the mining industry has historically lagged behind other sectors, such as the oil industry, in implementing automation and measuring instrumentation – a big mistake. According to Thwaites, measurement is the cornerstone of control and efficiency. “If you have a poor measurement, or no measurement, you can’t do good control,” he explained. But this is changing. More and more mining companies are conscious of improved measurements and endorsing control, automation and next-generation technologies. What is more, there has been significant progress in automated instruments recently. These measure crucial parameters in the processing circuit and equipment to allow operators to monitor and adjust process control as needed. In particular, measurements relating to particle size in the grinding circuit, flotation variables and thickener bed mass have come a long way.

Particle size measurement in the grinding circuit

Historically, measuring particle size after grinding was done infrequently, if at all, because it required too many samples to be sent to a lab. Yet this measurement is key to plant efficiency and performance. Over-grinding wastes energy and under-grinding leads to particles that are not liberated or are too coarse, which in turn cuts the effectiveness of flotation and results in minerals lost to tailings. “Often the grinding capacity also turns out to be the production bottleneck,” said Jari Moilanen, director of Outotec’s automation product line, which specializes in process technology. “So if you can squeeze out more tonnes by grinding just enough, you’re not only saving energy and reducing chemical cost and use, which has environmental impact, but also increasing your capacity.” It is no easy task to accomplish on its own, according to Moilanen. Because the ore body can have so many variations, operators need a measurement that responds immediately to changes October/Octobre 2015 | 55


Courtesy of XPS Consulting & Testwork Services

The XPSFloatTM uses ultrasonic technology to measure pulp level during flotation.

PSI particle size analyzers, for example, employ laser diffraction technology. The analyzer automatically takes samples from process streams every three minutes and sends a laser beam through them. When the light beam hits a particle, it diffracts slightly. Based on that diffraction, the particle size and distribution can be calculated immediately. Because it is a non-contact technology, the analyzer is not affected by dust and buildup. More importantly, constant measurements, fast sample analysis and automated adjustments allow for optimum grinding balance, said Moilanen. In order to enable optimal mineral liberation in flotation, particle size needs to be measured in the grinding circuit product stream that is feeding flotation. Typically, the best sample point is the hydrocyclone overflow stream after secondary grinding. If there are several parallel grinding circuits, it is necessary to measure the end product of each grinding circuit. The PSI500i analyzer is available in 1-stream, 2-stream and 3stream configurations.

Flotation-level measurement

in the feed for control purposes. The measurement technology needs to correspond accurately to the laboratory measurement and it must be robust enough to enable continuous grinding control and optimization. In this, there has been progress. Today, it is possible to monitor particle size more reliably in real time at the plant. Outotec

56 | CIM Magazine | Vol. 10, No. 6

“Flotation cells have been around for more than 100 years and, over that time, minimal automation has transpired that would enable the flotation process to run in a highly efficient manner,” said Robert Stirling, managing director of FloLevel Technologies. Measuring flotation levels to achieve the highest possible high grade recovery is a daunting balancing act. The goal is to create just the right depth of froth at the top, which Thwaites compares to the froth in a glass of beer. “The bigger the froth column, the cleaner the froth will be, which means a higher grade of the concentrated minerals,” said Thwaites. “The smaller the froth column, the lower the grade, but the higher recovery. Every second, there’s new feed coming in. Sometimes the density is changing and sometimes the grade is changing, but the flow is always changing.” The difficulty is that the variables that need to be monitored to achieve the optimal balance between recovery and grade are in constant flux due to the ever-changing ore head grade characteristics of slurry and conditions within the flotation cell. From the chemicals to the water and airflow used to control the velocity and density for optimal separation, froth management is dynamic. Manual tests typically used in mills can be inherently flawed, such as the one metallurgists use to determine suspended solids density which is taken every four hours or so. “They weigh the content on a scale next to the flotation cell to determine the solids ratio. They then go to the control room and make adjustments to water addition, et cetera,” said Stirling. “Meanwhile, the suspended solids concentration has changed again in the time it takes to walk to the control room.” Since the flotation pulp level has proved difficult to measure directly, traditional mechanical measuring technology such as floating balls also have their problems; for example, solids can cover the balls, altering their buoyancy and accuracy. “The challenge for industry is to get a decent, accurate measurement – every second,” said Thwaites. “We also need


XPS is a licensed metallurgical consulting, technology and test ser vices business of fering industr y leading exper tise in orebody FKDUDFWHULVDWLRQĂ€RZVKHHWGHYHORSPHQW operational suppor t, growth initiatives and asset integrity management for most commodities including gold, nickel, copper, zinc, PGEs, rare ear ths, chromite and industrial minerals. Our ser vices to clients include plant suppor t, FRPPLVVLRQLQJLPSURYLQJRSHUDWLRQDOHI ÂżFLHQF\ DQGJUHHQÂżHOGEURZQÂżHOGSURMHFWGHYHORSPHQW ;36FRPSULVHVRIÂżYHGLVWLQFWEXWLQWHJUDWHG business groups representing the ffo ollowing key disciplines:

Courtesy of Hawk Measurement Systems

to know if [the flotation level] is in control and trending down or up.� Real-time flotation-level monitoring, done on each bank of flotation cells, is clearly the solution, but using the proper measuring instrument has had its own challenges. Particle buildup on the measurement instruments and the issue of going inside the flotation cell to take measurements of the froth column are particular cases in point. One product that has addressed this is the XPSFloatTM that uses ultrasonic technology to produce highly accurate measurements of the flotation pulp level. The flat-bottomed, conical float in the device sits on the pulp/froth interface, allowing accurate calculations of the froth column. “It offsets the exact level of the pulp, which can’t be measured visually or directly,� said Thwaites. Because there is no contact, it has minimal moving parts and only a small, angular surface, minimizing buildups. A retrofitted XPSFloatTM typically costs about $6,000 per bank. Another step forward has come from FloLevel Technologies. The company’s FloLevel system is self-cleaning, measures pulp and froth height and can measure process variables, froth density and suspended solids concentration in individual flotation cells. The technology uses transducers – devices that convert one form of energy to another – to emit sequential high-powered acoustic sound pulses into the flotation cell and receive

them back. The different signals from froth and pulp allow Hawk Measurement the technology to track Systems’ ORCA the interface between the two. sonar system Although immersed in the slurry and froth, the FloLevel transducers self-clean ultrasonically. According to Stirling, operators need one FloLevel system for every bank of cells and cost varies on the application and control range. Outotec’s LevelSense measures slurry level and froth thickness using electrical impedance tomography technology, originally developed for medical imaging. The instrument consists of a probe with measurement electrodes attached to it that is immersed in the flotation cell and scans the different

Mineral processing testing, QEMSCAN, quantitative mineralogy, sampling and applied statistics Pyrometallurgical and hydrometallurgical testing, process modeling and on-site suppor t Process control, automation technologies and engineering solutions Materials engineering for the selection and testing of materials of construction, failure analysis and equipment monitoring In-plant, hands- on technical assistance from a team of experienced metallurgists available to assist with commissioning, process optimization, review and suppor t

EXPERT PROCESS SOLUTIONS Contact us:

+1 705 699 3400

info@ xps.ca

ww ww w.xps.ca

6 Edison Road, Falconbridge, Ontario, Canada P0M 1S0 Director: Dominic Fragomeni dominic.fragomeni@ xps.ca

October/Octobre 2015 | 57


conductivities around it. It calculates where the slurry, froth and air meet and interact as well as the froth density and height. With no moving parts, LevelSense typically requires little to no maintenance. LevelSense instruments are normally used in each flotation cell.

Thickener levels

As with flotation, thickener optimization is all about balancing the equipment with the processing. From the feed’s flow rate, underflow (extraction), bed level and mass, to flocculent dosing and overflow clarity, there are many components and several measuring points. “The best way to optimize a thickener is to have the most information and measurements,” said Endress + Hauser Canada’s Rick Hemingway, whose company offers an integrated package that optimizes all the critical measuring points. Thickener bed levels are especially important; without good flocculent control and bed mass and height measurements, the thickener will not function properly. “If you put too much material in and fail to extract at an appropriate rate, you risk stopping the rakes and then having to shut down the plant and muck it out, which is a horrible, costly job,” said Thwaites. Endress + Hauser’s Turbimax provides continuous measurement of the separation of liquids and sediment in the thickener beds using submersible ultrasonic level sensors. The time it takes for the ultrasonic signals generated by Turbimax to bounce back when they hit solid particles is used to calculate bed levels. Hawk Measurement Systems, which also has a range of integrated measurement and automation for thickener optimization, has developed the ORCA sonar system, which is attached to the top side of the thickener. “It’s able to penetrate down to the compacted bed level without interference of the lighter-density material,” said Steve Stone, Hawk Measurement’s vice-president of sales and marketing. The system also measures the lighter density material above the bed and the clarity of the water at the top level. That is because the ORCA sonar has the capability of emitting two different frequencies, one for measuring light density and the other for heavydensity interfaces.

Closing the loops with good measurements

Every milling plant has hundreds of potential measuring points that simply cannot be effectively monitored, measured and controlled manually, yet each one is critical to the overall efficiency. “You could easily be at 500 control loops in a big plant – so we are trying to do all these measurements continuously in order to do good control,” said Thwaites. “The operator’s job is then to set the optimum levels, or oversee the advanced controls and the equipment, but his job becomes much more complicated if the measurements and controls are not working properly or are not there at all. It’s all interconnected, interactive and it’s a multivariable control, but if you don’t measure the individual pieces, you won’t be able to run the circuit control and mill effectively.” CIM 58 | CIM Magazine | Vol. 10, No. 6


SECTION francophone 65 Champ visuel

70 Durs enseignements

Alors qu’elles avaient jusqu’ici été ignorées des sociétés minières, les machines de triage deviennent une solution de plus en plus courante pour réduire les déchets et les dépenses

L’équipe de Palabora Copper, désormais mieux préparée pour son projet de foudroyage par blocs de l’exploitation Lift I, puise dans son expérience pour aller plus loin

Par Ian Ewing

Par Michael Yang

60 Lettre de l’éditeur 60 Mot du président 61 Les actualités en bref

La version française intégrale du CIM Magazine est disponible en ligne : magazine.CIM.org/fr-CA

74 Résumés techniques


lettre de l’éditeur

Le contrôle est essentiel

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râce au soutien ferme et constant de tous les membres de McEwen Mining, nous avons pu compiler en début d'année une série de vidéos sur les rencontres Mining Innovation Lunch and Learn (des dîners-conférences sur l'innovation dans l'industrie minière), que la société organise à intervalle de quelques mois dans ses bureaux de Toronto. Les présentations dans ces vidéos portent autant sur des discussions expliquant dans quelle mesure et dans quel domaine les changements progressifs peuvent réorienter l'industrie minière que sur des idées pour l'amélioration des procédés qui permettront d'augmenter de quelques pourcents les taux de récupération. S'il est peu probable que ces vidéos publiées sur YouTube suscitent un jour un élan de passion sur la toile, le fait que plus de 1 000 visiteurs du monde entier aient visionné une présentation consacrée à l'optimisation des procédés et au contrôle de la flottation par mousse vient confirmer toute la valeur de cette expérience médiatique. « Si vos mesures sont mauvaises, ou si vous ne disposez tout simplement d'aucune mesure, il n'est pas possible de procéder à un contrôle sérieux », explique Philip Thwaites de XPS Consulting & Testwork Services dans notre article de la section Technologie dédié au contrôle des procédés, dans lequel Alexandra Lopez-Pacheco explique en détail les progrès technologiques qui rendent possibles ces mesures et ce contrôle (p. 55, uniquement disponible en anglais). C'est un message récurrent dans le numéro de ce mois-ci. Le manque d'informations peut mener à des résultats médiocres ; c'est l'une des leçons qu'a tirées l'équipe des opérations de Palabora Copper lorsqu'elle a transformé sa mine à ciel ouvert en une mine souterraine en utilisant la méthode de foudroyage par blocs. La société est aujourd'hui plus riche et applique désormais ces leçons aux travaux qu'elle effectue dans la deuxième mine en cours de développement, laquelle est notamment équipée d'un système complet de surveillance. Michael Yang présente ce projet en p. 70. Dans le même ordre d'idée, notre article de fond rédigé par Ian Ewing (p. 65) porte sur les capacités croissantes des machines de triage du minerai qui permettent de limiter le temps et l'énergie perdus lorsque le minerai destiné à être un déchet est traité. Dans tous ces exemples, les mesures offrent un certain contrôle. Nous avions décidé il y a plusieurs mois de consacrer notre numéro d'octobre au traitement du minerai et au contrôle des procédés, avant même de publier cette vidéo sur Internet. Les données de consultation de cette dernière viennent cependant confirmer que nous avions pris une sage décision. Nous savons comment la vidéo a été trouvée, sur quel site elle a été visionnée, si elle a été partagée et par quel biais, et combien de temps en moyenne elle a été regardée. Grâce à ces informations et en les peaufinant un peu, nous serons en mesure d'améliorer la diffusion et la promotion de nos prochaines vidéos. De fait, il s'agit là de notre propre incursion dans la sphère du contrôle des procédés.

Ryan Bergen, Rédacteur en chef editor@cim.org @Ryan_CIM_Mag 60 | CIM Magazine | Vol. 10, No. 6

mot du president

Un objectif commun

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haque industrie doit relever des défis en matière de diversité, qu’il s’agisse du secteur de la technologie, considéré comme étant le plus avancé et le plus novateur, ou du secteur minier, ce qui n’est guère surprenant. Je dis cela parce que l’industrie minière est encore considérée comme un « club réservé aux hommes. » C’était peut-être vrai dans le passé, mais l’industrie minière a beaucoup progressé et est devenue, à certains égards, une des industries les plus progressistes et les plus novatrices. Nous avons été à l’avant-garde de nombreux domaines, dont l’automatisation, la sécurité, la gérance de l’environnement et la responsabilité sociale d’entreprise, pour n’en nommer que quelques-uns. Rien ne nous empêche de faire preuve de ce même leadership en ce qui a trait à la diversité. En regardant mes collègues féminins et masculins à la table du Conseil de l’ICM, je n’ai que de l’admiration pour eux. Chacun d’eux apporte un point de vue et une dynamique unique en son genre qui rehaussent l’ICM dans son ensemble et qui aident à renforcer son statut de centre d’excellence. Nous avons beaucoup progressé, mais il nous reste encore un bon bout de chemin à faire. L’an dernier, la Commission des valeurs mobilières de l'Ontario (CVMO) a incité l’industrie à s’améliorer en mettant en place des règles sur l’obligation de déclaration. Celles-ci enjoignent les sociétés cotées en bourse à décrire leurs efforts en vue d’améliorer la représentation des femmes parmi leurs cadres dirigeants et leurs conseils d’administration ou à expliquer leur absence, le cas échéant. D’après les premiers indicateurs, il semble que la majorité des sociétés déclarantes ont décidé de s’y conformer et d’adopter des politiques officielles en matière de diversité. Il est triste qu'en dépit de l'abondance des données indiquant que les conseils d’administration diversifiés peuvent faire fructifier le rendement, nous devions encore être poussés à faire de tels changements. En tant que père de deux adolescentes, cela est inacceptable pour moi, comme ça l’est pour elles. Je vais encourager mes filles à suivre l’exemple de la chef de l’exploitation de Facebook, Sheryl Sandberg, à « aller de l’avant » et à être responsables de la progression de leur propre carrière. Toutefois, à titre de dirigeants, nous devons aussi mettre l’épaule à la roue et assumer notre part de responsabilité. Le moment est venu pour nous tous d’aller de l’avant!

Garth Kirkham Président de l’ICM @GarthCIMPrez


Les actualités en bref Au cours des 50 dernières années, les sciences relatives aux mines, à la métallurgie et aux matériaux n’ont cessé d’aller de l’avant, mais une partie de leur culture semble être restée figée dans une autre ère. La participation des femmes dans ce domaine est en effet encore terriblement faible. « Nous avons eu cette même discussion il y a 45 ans », indiquait Carolyn Hansson à l’occasion du symposium Women of Impact, un forum d’une journée dédié aux femmes influentes qui s’est tenu lors de la conférence des métallurgistes (COM 2015). Mme Hansson, la première étudiante et titulaire d’un doctorat en métallurgie de la Royal School of Mines d’Imperial College London, faisait partie d’un groupe de professionnelles présentes à l’événement. Ces femmes, qui se sont forgées une carrière contre vents et marées, ont toutes partagé leurs expériences de personnalités singulières dans l’industrie. Le symposium venait compléter une toute nouvelle publication intitulée Women of Impact in the Canadian Materials, Metallurgy, and Mining Fields (femmes influentes dans les domaines des matériaux, de la métallurgie et des mines au Canada), laquelle présente 18 femmes qui sont venues occuper le devant de la scène dans ces disciplines depuis toujours dominées par des hommes. Mary Wells, présidente de la MetSoc, en collaboration avec Anne Millar, candidate au doctorat d’histoire de l’université d’Ottawa, a compilé les profils biographiques de ces femmes afin de mettre en lumière les multiples options professionnelles qui s’offrent aux femmes se préparant à cette sphère du domaine du génie. Plusieurs groupes de spécialistes dirigés par des femmes présentées dans l’ouvrage participaient au symposium,

Avec l’aimable autorisation de la société de la métallurgie et des matériaux (MetSoc)

Exercer une influence sur la diversité

(De gauche à droite) Liana Centomo, Priti Wanjara, Shari Graydon, Janice Zinck et Annette Bergeron débattent des problèmes liés à la mixité dans l’industrie minière à l’occasion du symposium Women of Impact, un forum d’une journée dédié aux femmes influentes qui s’est tenu lors de la conférence des métallurgistes (COM 2015).

et chaque intervenante offrait ses propres expériences et son style. Jennifer Jackman, directrice générale retraitée de CanmetMATÉRIAUX,

faisait remarquer que, tout au long de sa carrière, elle avait dû lutter contre « la discrimination insidieuse qui pousse à réprimer nos attentes » et

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October/Octobre 2015 | 61


avait compris plus tard à quel point cette attitude l’avait changé. « Lorsque je suis devenue directrice, j’étais battante à l’excès », indiquait-elle. Janice Zinck, qui vient d’être nommée directrice de la section Métaux stratégiques à Ressources naturelles Canada (RNCan), a à son tour présenté une liste de stratégies professionnelles sur les thèmes suivants : « définissez ce que la réussite signifie pour vous » ; « apprenez à vous sentir à l’aise dans des situations pesantes » ; et « trouvez votre propre équilibre entre vie professionnelle et vie privée. » Ces conseils auraient tout aussi bien pu concerner la poignée d’hommes étudiants présents, sauf peut-être lorsqu’elle suggérait aux femmes de tirer au maximum profit de leur singularité. « Si vous êtes une scientifique, vous sortez déjà du lot, ce qui est une bonne chose ! » Mme Wells était d’accord avec Mme Hansson sur le fait qu’il est très frustrant pour les femmes d’être encore à ce jour sous-représentées dans le secteur des mines et de la métallurgie, et ce malgré les discussions à ce propos. Avant que des progrès significatifs ne puissent être faits, expliquait-elle, des changements structurels doivent se produire sur le lieu de travail. Fonder une famille ne devrait en aucun cas constituer une entrave à la vie professionnelle. « Les employeurs doivent accorder aux femmes une certaine flexibilité leur permettant de réintégrer le marché du travail »,

62 | CIM Magazine | Vol. 10, No. 6


expliquait-elle, citant comme lueur d’espoir la société de raffinage du zinc CEZinc. « Toutes les réunions dans cette société se terminent à 16h30, ce qui permet à tou(te)s d’aller récupérer leurs enfants si besoin est. » Les exemples de réussite de ces femmes représentaient un critère important pour de nombreuses étudiantes. Victoria Zyma, étudiante de troisième année en génie mécanique, indiquait qu’elle se sentait plus à l’aise de savoir qu’elle pouvait « combiner vie de famille et carrière. » Pour Sarah Hall, étudiante de premier cycle en génie chimique à l’université McMaster, le message le plus fort de la journée était le suivant : « le parcours professionnel n’est – Ryan Bergen pas un long fleuve tranquille. »

Barrick établit un modèle de président unique Cet été, Barrick Gold a procédé à des améliorations majeures dans sa structure de haute direction. La société aurifère a nommé Kelvin Dushnisky au poste de président unique de la société, un titre qu’il partageait jusqu’ici avec le coprésident Jim Gowans, lequel se prépare à prendre sa retraite de Barrick. M. Gowans, qui avait rejoint l’équipe de direction de la société minière en janvier dernier, restera au sein de la société jusqu’au 31 décembre au titre de conseiller du président afin de l’aider à procéder à un certain nombre de changements supplémentaires au niveau du personnel. « En allégeant notre structure et en devenant plus efficaces et davantage orientés sur un nombre plus restreint d’actifs principaux, nous donnons la possibilité à nos chefs de file de ce domaine de fonctionner davantage comme de véritables propriétaires d’entreprise », déclarait John Thornton, président de Barrick, dans un communiqué de presse. « C’est dans cet esprit que [M. Gowans] a encadré et formé nos chefs de file opérationnels », ajoutait Andy Lloyd, vice-président des communications de la société. « Nous avons choisi le bon moment pour accélérer cette transition. » La coprésidence a commencé en juillet 2014 après le départ de Jamie Sokalsky de son poste de président et directeur général et suite à l’élimination de ce poste. Parmi les autres changements au sein de la société, citons la nomination de Richard Williams au poste de directeur de l’exploitation, lequel occupait jusqu’ici le poste de chef du personnel. Basie Maree a également été nommé directeur des techniques informatiques (DTI) après avoir occupé le poste de vice-président directeur des services techniques de la société. Ces changements représentent une étape supplémentaire vers la mise en œuvre de la stratégie de Barrick sur le long terme visant à réduire ses dépenses de 2 milliards $ d’ici la fin de l’année 2016 ainsi que sa dette. « Cette structure élimine les couches hiérarchiques ainsi que la bureaucratie et augmente la transparence au sein de l’organisation, ce qui contribue à soutenir notre objectif principal visant à optimiser le flux de trésorerie dispo– Katelyn Spidle nible », indiquait M. Lloyd. October/Octobre 2015 | 63


Hommages et consécrations à la COM 2015 Avec l’aimable autorisation de la société de la métallurgie et des matériaux (MetSoc)

Cette année, les esprits les plus gie. Le symposium dédié à la brillants au monde dans le mémoire de Torstein Utigard domaine de la métallurgie ont commémorait les accomplisseoffert plus de 300 présentations à ments en métallurgie extractive l’occasion de la conférence des de ce professeur de l’université de métallurgistes (COM 2015). Cet Toronto. Pour célébrer son 65e événement annuel, organisé par anniversaire, un symposium a été la société de la métallurgie et des dédié à David S. Wilkinson pour matériaux (MetSoc) de l’ICM, sa contribution à la science et la s’est tenu du 23 au 26 août 2015 technologie des substances à l’hôtel Fairmont Royal York, à solides. Toronto, conjointement avec Le dernier jour de la confél’America’s Conference on Al Alloys rence, le symposium Women of (AMCAA, la conférence amériImpact (un symposium dédié aux Mary Wells, professeure de génie à l’université de Waterloo, est caine sur les alliages d’alumi- la présidente de la MetSoc et de la conférence des femmes influentes) a mis à l’honnium), laquelle a ajouté quelque métallurgistes (COM 2015) cette année. neur des personnalités féminines 100 présentations au programme. canadiennes telles qu’Ursula Mary Wells, professeure de génie à présidente et directrice générale de Franklin, métallurgiste de renom, l’université de Waterloo et présidente CEZinc, qui portait sur la durabilité activiste et professeure à l’université de la conférence cette année, a inau- dans le domaine de l’hydrométallur- de Toronto. – Peter Braul guré l’événement avec la séance plénière le lundi 24 août en annonçant • PRIX • les présentations de Donald Sadoway du Massachusetts Institute of TechnoPrix Airey de la MetSoc : Prix Sherritt de l’hydrométallurgie : Chris Twigge-Molecey, Hatch Ed Lam logy (MIT, l’institut de technologie du Massachusetts) et de Maurits Prix dédié aux sections Prix de l’innovation de la MetSoc : étudiantes de la MetSoc : le procédé SART Van Camp d’Umicore. M. Sadoway s’est université Laval Prix Brimacombe de la MetSoc : montré particulièrement véhément Bourse de maîtrise de la MetSoc : Mansoor Barati, université de Toronto quant à son opinion sur les métallurRebecca Radzinski, université Queen’s Médaille d’argent : gistes et l’impact positif important Bourse de doctorat de la MetSoc : Mahi Sahoo, Suraja Consulting que ces spécialistes peuvent avoir sur Alexander Burns, Prix de l’excellence de la recherche le monde. « Je souhaite réunir des université de la Colombie-Britannique (UBC) de la MetSoc : jeunes gens enthousiastes, qui n’ont Prix du meilleur article de la MetSoc : Daolun Chen, université Ryerson peur de rien et qui savent que rien W. Wulandari, G.A. Brooks, M.A. Rhamdhani PRIX DÉDIÉS À L’HYDROMÉTALLURGIE : n’est impossible. » et B.J. Monaghan, pour leur article Kinetic analysis of silicothermic process Confrérie de l’ICM – La conférence, dont l’objectif est underflowing argon atmosphere Roman Berezowski de partager les connaissances et la Prix du meilleur article de la section des Prix Gordon M. Ritcey – passion pour ce domaine, est égalemétaux légers : Alexander Burns, université ment l’occasion de rendre hommage C. Siemers, F. Brunke, K. Saksl, M. Kohnke, de la Colombie-Britannique (UBC) aux carrières passées et actuelles de G.J. Ackland et B. Tegner, pour leur article BOURSES DE LA SECTION personnalités importantes du Development of oxidation resistant titanium HYDROMÉTALLURGIE : alloys by niobium addition domaine de la métallurgie. C’est à Bourse d’études de premier cycle – l’ancien président de l’ICM Chris Prix du meilleur article de la section Justin Riggio, université McGill pyrométallurgie des métaux non ferreux : Twigge-Molecey, conseiller supérieur J. Jansson, P. Taskinen et M. Kaskiala, pour Bourse Lucy Rosato – chez Hatch, qu’a été décerné le prix leur article Freeze lining formation in Caitlyn McKinley, université Queen’s Airey, la récompense la plus presticontinuous converting calcium ferrite slags PRIX DE L’ICM gieuse du secteur canadien de la Prix du spécialiste émérite en sciences métallurgie en reconnaissance de sa Confrérie de l’ICM : Roman M. Berezowski, des matériaux de la MetSoc : James John Budac, Xinin Cao contribution remarquable à l’indusAkaram Alfantazi, université et Nils Voermann de la Colombie-Britannique (UBC) trie tout au long de sa carrière. Cette Éminent conférencier année, trois symposiums ont été orgaPrix de l’environnement de la MetSoc : de la MetSoc de l’ICM : Charles Q. Jia, université de Toronto nisés à titre honorifique, dont l’un Wilson Pascheto dédié à la mémoire de Lucy Rosato, 64 | CIM Magazine | Vol. 10, No. 6


CHAMP VISUEL Par Ian Ewing

LA TENEUR DU MINERAI

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Montage photo : Elissa Ebersold, photographie originale fournie par Copper Mountain

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La technologie de triage du minerai promet de fournir une alimentation plus uniforme au concentrateur.

« En moyenne dans l’industrie minière, les activités de concassage et de broyage absorbent à elles seules 44 % de la consommation totale d’électricité », peut-on lire dans le premier paragraphe

d’une étude de 2014 publiée dans la revue Minerals Engineering. Mais quelle quantité du matériau

concassé et broyé a réellement de la valeur ? Dans toute l’industrie, entre 30 et 60 % du matériau traité ne contient pas de minerai.

Les sociétés minières ont constaté qu’elles pouvaient considérablement réduire leurs dépenses énergétiques et améliorer leur rentabilité en utilisant une technologie de détection avancée pour éliminer tous les déchets : le triage du minerai. Joe Lessard, ingénieur de projet chez Orchard Material Technology et principal auteur de cette étude, fait partie d’un nombre croissant d’initiés de l’industrie qui pensent que le triage du minerai engendrera de grands changements en termes d’utilisation par les sociétés minières de l’énergie. « Aucune technologie ne permet d’améliorer le matériau autant que le triage du minerai, à des coûts d’intrants si bas », indiquait M. Lessard. « Les retombées économiques sont si exceptionnelles et rapides que cela mérite largement d’y consacrer une étude de faisabilité, de la transposer à l’échelle

préindustrielle et de lancer rapidement la production à grande échelle. » Les secteurs des diamants et de l’uranium utilisent beaucoup cette technologie. Cependant, pour la plupart des minéraux, le triage automatisé du minerai n’a jamais vraiment été accepté, malgré son entrée sur le marché de l’industrie minière dans les années 1960. La première génération de trieuses automatisées s’était forgée une mauvaise réputation en raison de la faible résolution des capteurs, de leur mobilité médiocre, des coûts d’investissement élevés et, la partie la plus problématique, de la faible capacité de traitement des matériaux. Cette technologie a été pratiquement abandonnée dans l’industrie minière avant même qu’elle n’ait véritablement été adoptée. October/Octobre 2015 | 65


La technologie de triage peine à prendre ses marques depuis son lancement ; elle a vieilli lentement et a fini par trouver une application à plus grande échelle dans les secteurs de la transformation des produits alimentaires, du recyclage et de la ferraille. Aujourd’hui, grâce à des capteurs de meilleure qualité et à une plus grande puissance informatique, cette technologie devient plus performante. En outre, l’évolution des aspects économiques dans l’industrie minière a fini par convaincre les dirigeants du secteur minier d’ouvrir leurs portes à M. Lessard et à d’autres lorsqu’ils se sont présentés pour discuter de cette technologie jusqu’ici rejetée.

Minéraux adaptés au triage : Baryte Calcite Charbon Porphyre cuprifère Cuivre-or Diamant Or (par association) Fer Plomb Calcaire Molybdène

Nickel Sulfures de nickel Nickel-cuivre Phosphates Platine Potasse Terres rares Métaux réfractaires Talc Tungstène Uranium Zinc

Technologies de détection actuellement utilisées, et ce à quoi elles servent généralement :

Logique économique

Électromagnétique (certains métaux communs) Magnétique (pour tout minerai doté de propriétés magnétiques) Proche infrarouge (NIR) (minéraux industriels dont la calcite) Optique (tout minerai présentant une distinction au niveau des caractéristiques visuelles, notamment la couleur) Radiométrie (matériaux radioactifs, particulièrement l’uranium) Ultraviolet (UV) Fluorescence des rayons X (XRF) (détection de surface) Luminescence des rayons X (XRL) (détection de surface, pour les diamants) Transmission des rayons X (XRT) (probablement plus polyvalent : plus adapté aux métaux communs ; pour la détection en vrac, pour tout minéral qui présente des densités atomiques différentes)

déclin dans les exploitations existantes du monde entier, de pénurie de nouvelles découvertes de haute qualité, d’inflation poussée par la hausse des coûts des facteurs de production tels que l’énergie, et de prix qui ne sont pas suffisamment élevés pour supporter le coût actuel des activités dans le secteur minier. » D’après M. Bamber, le triage du minerai constitue le remède naturel à ces problèmes. « Les mines en général, qu’elles soient à ciel ouvert ou souterraines, incluent une quantité considérable de déchets dans ce qu’elles qualifient de “ minerai ”. Si l’on peut éliminer ces déchets, on pourra améliorer l’économie de base dans tout le secteur minier. »

Principes fondamentaux

Montage photo : Elissa Ebersold

« Il y a trois ou quatre ans, lorsque nous avons réellement comLes machines modernes de mencé à nous investir dans l’industriage du minerai sont équipées de trie minière, il nous a vraiment fallu nombreuses technologies de détecexercer une forte pression pour orgation (voir encadré) et de mécaniser ces réunions », indiquait Jason nismes de triage, mais le principe Looman. Président de Steinert US, fondamental est identique dans un fabricant majeur de machines de chacune d’elles ; en détectant la triage, M. Looman a constaté un composition d’un volume de matéintérêt croissant pour cette technoriau ou de roches isolées, elles peulogie. « Ainsi, ce n’est plus nous qui vent identifier les déchets dont la les appelons, mais les centres d’ingévaleur économique est faible et les nierie et les utilisateurs finaux qui séparer du minerai affichant une font appel à nos services et nous plus grande valeur avant de dépendemandent de venir leur parler de ser des sommes conséquentes pour cette technologie, et de leur explileur traitement. Sources : Joe Lessard, Andrew Bamber, Arvin Mazhary, quer ce qu’elle peut ou ne peut pas Le format traditionnel de ces Darren Koningen, Jason Looman, Chris Rule faire. Ne serait-ce que ces six dertrieuses consiste en une machine à niers mois, nous avons constaté une grande évolution. » courroie qui est située en amont des circuits de broyage et de On peut facilement comprendre pourquoi. L’industrie est concentration et analyse, en quelques nanosecondes, le mineconfrontée à des enjeux structurels que les méthodes minières rai brut broyé et précalibré alors qu’il est transporté sur la actuelles ne permettent pas de gérer. « Le niveau des prix com- courroie. Un dixième de secondes plus tard, en fonction de la mence à donner un sens aux technologies de triage », expli- composition de chaque roche placée sur la courroie, une série quait M. Lessard. « Le coût de l’électricité, de l’eau et d’autres de buses à air comprimé séparent les déchets du minerai et services nécessaires dans le processus indiquent tout à coup les envoient dans des cheminées distinctes à mesure que les le besoin de disposer de solutions technologiques plus effi- roches avancent vers le bout de la courroie. La teneur de coucaces. Nous ne pouvons plus passer notre temps à broyer car pure est déterminée par des études de faisabilité avant la mise le coût de l’électricité est trop élevé. » en œuvre, mais elle peut être facilement recalibrée à mesure qu’évoluent les plans et les aspects économiques de la mine. Andrew Bamber, président et directeur général de MineSense, une entreprise en démarrage de triage basée à VancouM. Lessard, dont l’étude portait sur le bien-fondé éconover, voit un potentiel encore plus fort dans cette tendance. mique du triage du minerai, fait remarquer qu’avec une miné« C’est le moment idéal de déployer une technologie qui per- ralisation hétérogène adéquate, le détournement d’une petite met d’améliorer les marges de profit », expliquait-il. « Nous partie des déchets apporte une valeur ajoutée importante. nous trouvons actuellement dans un contexte de teneurs en Dans l’une des études de cas qu’il a menée, l’investissement 66 | CIM Magazine | Vol. 10, No. 6


Montage photo : Elissa Ebersold

En évitant d’envoyer les déchets vers le concentrateur, les sociétés minières pourraient réaliser de grandes économies au niveau de leurs coûts d’exploitation et dépenses en capitaux.

de 9,6 millions $ pour acheter et installer une machine de triage à l’échelle pilote portait rapidement ses fruits, car elle générait entre 7 et 9 millions $ en revenus supplémentaires annuellement. « Même avec une trieuse de qualité médiocre, qui rejette seulement 30 % de l’alimentation en déchets, les avantages financiers sont tout de même visibles en moins de deux années », indiquait-il. « C’est assez surprenant, même pour nous, de constater dans les chiffres à quel point cette technologie peut se révéler profitable. » La société Minera Alamos est prête à parier que ces facteurs économiques vont évoluer. Cette petite société minière a récemment dû revoir les plans de la mine pour son projet de cuivre et molybdène Los Verdes à Sonora, au Mexique. « La peur qui hante cette région est qu’il n’existe pas d’usine de concentration à proximité », expliquait Darren Koningen, président de la société. Cependant, en utilisant une machine de triage à rayons X par transmission (XRT) pour la préconcentration du minerai, le transport du minerai vers un concentrateur plus éloigné est devenu viable sur le plan économique. « Plutôt que de modifier le plan de la mine en vue de ne classer que le minerai dont la teneur est de, disons, 1 % de cuivre, et de perdre tout le matériau de teneur moyenne ou faible », expliquait M. Koningen, « nous pouvons extraire pratiquement l’intégralité du matériau en installant cet équipement de triage et utiliser la machine pour rejeter toutes les roches broyées dont la teneur est de moins de 0,5 %. » « Nous essayons d’obtenir un minerai dont la teneur sera double, voire plus, tout en maintenant nos récupérations dans la gamme des 90 %. Ces 90 % font partie d’un réservoir de ressources plus important, car nous procédons maintenant à l’extraction de davantage de matériau dont la teneur se situe entre 0,5 et 1 % que nous aurions autrement jeté dans l’amas de déchets. »

Le plus tôt sera le mieux Réduire la quantité de matériau juste avant la comminution peut engendrer d’importantes économies en termes d’énergie (et d’argent), mais M. Bamber de MineSense préfère intervenir encore plus tôt dans le schéma de traitement. « Dans ShovelSense (le produit phare de MineSense), nous avons développé une technologie particulièrement transformationnelle qui permet aux exploitants de mines de mesurer, signaler et décider de la teneur des matériaux en vrac au point d’extraction », expliquait-il. En équipant les pelles et les chargeuses frontales de tous les capteurs et processeurs nécessaires, les exploitants peuvent immédiatement établir l’acheminement du minerai pour le traitement ou vers le terril dès l’extraction, avant qu’il ne soit transporté ou qu’il ne subisse quelque traitement que ce soit. « Pendant qu’une benne sous terre charge le matériau de la chambre ou qu’une pelle charge le matériau de la berme, nous avons le temps de prendre une mesure grossière, d’indiquer sa valeur et de la comparer à la valeur attendue », expliquait-il. Les essais actuels sur le terrain montrent que les machines de triage de la société confirment les données existantes de la mine environ 70 % du temps. Cependant, les 30 % restant de matériau, qui seraient autrement classés incorrectement ou mal acheminés, représentent une perte considérable de valeur (lorsque le minerai est classé comme déchet) et une augmentation des coûts (lorsque les déchets sont traités comme du minerai). Dans l’une des exploitations que MineSense a analysé, une amélioration de 50 % du processus de contrôle de la teneur et d’acheminement du minerai viendrait ajouter 370 millions $ à la valeur nette actuelle de la mine. Un avantage supplémentaire, indiquait M. Bamber, est que la détection et la classification en temps réel au point October/Octobre 2015 | 67


Montage photo : Elissa Ebersold, photographie originale fournie par Copper Mountain

Les gisements hétérogènes sont ceux qui pourront tirer le meilleur parti du triage du minerai.

d’extraction peuvent aider à améliorer le plan de la mine à court terme ; en effet, les données sont recueillies avec chaque chargement et transmises par réseau sans fil aux système de gestion de la production. « La façon dont nous envisageons le triage des matériaux en vrac, basé sur des systèmes reposant sur des pelles ou des courroies pour leur transport, est qu’il améliore la modélisation des corps minéralisés et des blocs, les procédés à court terme et l’aménagement des mines. »

On constate également d’autres avantages auxiliaires ; par exemple, la préconcentration peut augmenter les ressources rentables, et ainsi accroître l’estimation de la mine. La capacité de production et les teneurs de coupure peuvent facilement être modifiées par l’exploitant de manière à répondre aux demandes du marché. En outre, cette technologie peut fournir un nouveau flux de rentrées, car le nouveau flux de déchets provenant des trieuses peut être revendu comme agrégat.

Améliorations des procédés de bout en bout

Le problème de l’échelle

Les points communs entre les différentes philosophies et techniques sont la capacité à extraire davantage de matériaux à des teneurs plus basses, à rejeter des quantités importantes de matériaux sans valeur et à procéder à la préconcentration du matériau avant qu’il ne soit traité. En plus d’utiliser moins d’électricité par once, livre ou tonne de métaux récupérés, le triage du minerai réduit aussi considérablement l’usage de consommables tels que l’eau et les agents réactifs. La préconcentration permet d’obtenir une teneur plus uniforme de la masselotte, de faciliter la gestion des activités en aval et souvent d’améliorer les taux de récupération, expliquait M. Lessard. Dans le cas des nouvelles usines, des économies en capital peuvent être réalisées car une plus petite usine est suffisante pour un plus faible volume de matériau ; par ailleurs, l’installation dans des usines existantes de la technologie de triage peut se traduire par une réduction des coûts d’exploitation en désactivant certaines unités non nécessaires. Moins de matériaux sont broyés en fines, aussi les bassins de décantation des résidus peuvent être plus petits, la durée de vie des mines prolongée et l’impact environnemental final d’une exploitation réduit. 68 | CIM Magazine | Vol. 10, No. 6

Les gains réalisés grâce à la technologie de triage sont considérables, mais il faut bien prendre en compte quelques remarques et considérations. L’hétérogénéité d’un gisement affecte l’utilité de toute machine de triage. « Si la dispersion du minerai est vaste et homogène et chaque roche qui ressort du triage affiche à peu près la même quantité du minéral présentant un intérêt, le triage ne sera pas utile. Que resterait-il à rejeter ? », demandait M. Lessard dans un élan rhétorique. « C’est cependant peu courant sur l’ensemble des corps minéralisés. Si la minéralisation et le partitionnement sont clairs, le triage du minerai peut présenter une grande valeur. » Par contre, savoir si les capteurs de triage permettent d’identifier un minéral est une autre affaire ; il n’existe actuellement pas de données à disposition du public permettant de déterminer quelle technologie de détection utiliser pour un minéral donné. Cependant, expliquait M. Lessard, « il est recommandé de toujours mener une étude de faisabilité ou de susceptibilité afin de tester si le minerai réagira ou pas. Vous écarterez peut-être rapidement la possibilité du triage car un minerai ne sera pas compatible avec la XRT, mais il se peut qu’il soit le candidat parfait pour la fluorescence des rayons X (XRF) ou le triage optique.


Jusqu’à ce que vous ayez essayé ces options, il est difficile de savoir si une technologie de détection marchera. » Entretemps, la liste des minerais pour laquelle le triage fonctionne ne cesse de s’allonger (voir encadré) ; en effet, les fabricants mènent des études de susceptibilité à l’aide de nouvelles technologies de détection, de capteurs plus performants et de meilleurs algorithmes sur des ordinateurs plus puissants. D’après M. Looman de Steinert, même les minéraux ne pouvant être détectés directement peuvent être des candidats au triage si on les associe dans le minerai à un minéral « traceur » qui est plus facile à trier. L’or, que l’on trouve souvent à l’aide de son association au quartz ou d’autres métaux, est un bon exemple. Le reproche de longue date concernant les capacités n’a cependant toujours pas été résolu. Chaque machine a actuellement une capacité de traitement de 100 à 200 tonnes par heure, ce qui est légèrement plus important qu’il y a une décennie. Pour les grandes mines de certains secteurs, cela ne suffit cependant toujours pas. « Cette technologie ne permettra pas à une machine de traiter 1 000 tonnes par heure », reconnaissait M. Looman. « On peut cependant créer un circuit comportant le bon nombre de machines pouvant traiter cette quantité, et cette solution sera toujours plus économique qu’une usine non équipée de ces machines. » Beaucoup de mines peuvent également envisager de n’ajouter qu’une machine de triage à un circuit combinant à plus petite capacité. Anglo American Platinum (AAP) est l’un des exploitants qui a ajouté « le bon nombre » de machines. Chris Rule, directeur de la technologie du concentrateur chez AAP, était chargé de la construction d’une usine de validation de concept équipée de quatre trieuses d’une valeur de 5 millions $ US sur le site du concentrateur nord de la mine Mogalakwena dans la province de Limpopo, en Afrique du Sud. Les trois années de travaux pilotes avec une seule trieuse dans une autre installation à Johannesburg ont mené à la construction de la nouvelle usine, qui pourra traiter 25 000 tonnes par mois. Cette dernière repose sur la technique de XRF pour détecter le cuivre et le nickel en tant qu’indicateur pour les métaux du groupe des platineux (ou éléments du groupe du platine, EGP). « L’amélioration du minerai constitue un besoin stratégique depuis plusieurs années pour AAP, et également pour l’industrie des EGP [dans son ensemble] », expliquait M. Rule. « Le désir de produire moins de tonnes pour davantage d’onces est un argument convaincant du point de vue économique, notamment au vu du déclin des teneurs du minerai et de la difficulté croissante à le traiter, de l’inflation supérieure à la moyenne, des coûts énergétiques croissants et des difficultés rencontrées en matière de productivité en Afrique du Sud. » Après plusieurs mois, ajoutait M. Rule, la technologie affichait les mêmes résultats en termes de création de valeur que lors des essais pilotes.

limites théoriques », concluait M. Lessard. « Inévitablement, ces limites technologiques ont été résolues. » Aucune trieuse ne pourra être efficace sur tous les sites miniers. Cependant, après avoir mené des tests de susceptibilité ainsi que les essais de terrain que les fabricants sont souvent prêts à effectuer pour prouver les capacités de leurs produits, une analyse économique relativement simple permet de déterminer si le triage est utile. « Je suis convaincu que le triage deviendra de plus en plus courant », prévoyait M. Koningen de Minera Alamos. « Cette technique peut avoir un impact sur les coûts d’investissement et d’exploitation, et de nos jours, c’est bien ce à quoi tout le monde aspire. » « De tous les marchés dans lesquels je travaille, le triage du minerai est le plus prometteur en termes de potentiel de croissance », ajoutait M. Looman. « Je pense que cette technique commence à être acceptée, particulièrement si l’on considère le nombre de demandes que l’on reçoit de la part de grandes sociétés d’ingénieurs. C’est au moment où les marchés sont à la baisse, comme c’est le cas actuellement, que l’on doit réellement trouver des solutions offrant des économies possibles. C’est une façon d’y parvenir. » ICM

Un nouvel ordre de trieuses « Nombre des problèmes rencontrés avec les anciennes machines de triage étaient d’ordre technique, et non pas des October/Octobre 2015 | 69


Avec l’aimable autorisation de Palabora Copper MountainPalabora Copper

L’équipe de Palabora a adopté la méthode de forage par montage pour développer ses tours de ventilation. La foreuse de montage est équipée d’un système permettant d’installer à distance un support de puits.

durs enseignements PAR MICHAEL YANG

orsque la société Palabora Mining Company (PMC) décidait de transformer sa mine géante à ciel ouvert en une exploitation souterraine il y a près de 15 ans, le producteur de cuivre sud-africain se lançait un défi phénoménal, celui de construire une gigantesque mine exploitée par foudroyage par blocs dans l’une des formations rocheuses les plus dures d’Afrique. L’exploitation qui en a résulté, baptisée Lift I, a établi des critères de référence dans l’industrie en matière de préconcassage et de conception intégrée, mais n’a pas pour autant été épargnée des difficultés initiales. Aujourd’hui, alors que PMC développe sa seconde exploitation, Lift II, plus grande et plus profonde, elle tire les enseignements du passé et s’appuie sur les nouvelles technologies pour s’assurer que ce projet d’une valeur d’un milliard $ soit couronné de succès. En théorie, la technique du foudroyage par blocs (ou méthode d’exploitation par blocs foudroyés) est relativement simple. Les travers-bancs dans la roche se trouvant en dessous du corps minéralisé provoquent un affaissement progressif des parois, formant ainsi une caverne artificielle dont les gravats s’écoulent vers le bas dans un système de canaux et de tunnels préconstruits. « Imaginez cette exploitation comme une mine à ciel ouvert renversée qui permet d’extraire les mêmes types de corps minéralisés massifs », expliquait Nick Fouche, directeur général de la croissance chez PMC. Pour une société dont l’expérience

L

70 | CIM Magazine | Vol. 10, No. 6

remonte à près d’un demi-siècle, et dont la production dans sa précédente mine à ciel ouvert s’élevait à 82 000 tonnes par jour (la plus grande en Afrique du Sud), cette transition en une mine équivalente sous terre aurait dû être relativement simple. L’expérience lui a cependant rapidement montré que la technique du foudroyage par blocs était loin d’être simple. « Notre expertise en matière de foudroyage par blocs faisait partie des meilleures de l’industrie, mais nous évoluions dans des terres encore inexplorées et il manquait de nombreux éléments à la société lorsqu’elle a commencé à développer l’exploitation Lift I il y a 15 ans », expliquait M. Fouche. « Notre équipement et nos procédés n’étaient pas toujours adaptés, et nous manquions d’expérience ; aussi, nous avons dû résoudre ces problèmes avant que l’exploitation ne devienne un exemple de réussite. » À l’heure actuelle, PMC est le seul producteur de cuivre en Afrique du Sud et la société fournit près de 80 % des métaux raffinés sur le marché local. L’exploitation à ciel ouvert dans la province de Limpopo est arrivée en fin de vie à la fin des années 1990, et la société a été l’une des premières au monde à directement transformer sa mine à ciel ouvert en une exploitation souterraine à l’aide de la méthode par blocs foudroyés, créant des précédents dans l’industrie avec un volume final de 30 000 tonnes par jour (t/j) et une caverne centrale de 450 mètres de hauteur. L’exploitation Lift I avait commencé à extraire du


PA L A B O R A

minerai en 2001, mais il faudra compter entre quatre et cinq ans avant que la production à Lift II n’atteigne sa pleine capacité en raison des problèmes rencontrés au niveau de la fragmentation de la roche. L’exploitation souterraine n’a pas fait l’objet d’une surveillance approfondie, aussi les estimations de la teneur du minerai n’étaient pas toujours précises. Ajoutez à cela l’affaissement de la paroi nord, et la mine devra arrêter ses activités bien plus tôt que prévu, abrégeant ainsi la durée de vie de l’exploitation à la fin de l’année 2015, et non en 2023. « Au vu de cette situation, nous avons commencé à envisager en novembre 2011 la possibilité d’un deuxième agrandissement de l’exploitation par foudroyage par blocs, 450 mètres juste en dessous de Lift I », expliquait M. Fouche. Une étude basée sur des données de 72 000 mètres de carottage a permis de conclure que le corps minéralisé plus profond est très identique en termes de taille, de forme et de teneur à celui de l’exploitation Lift I, à 0,64 % de cuivre ; ainsi, la société peut utiliser la même méthode pour exploiter la mine de manière économique. Lift II prévoit un volume de 33 500 t/j et un niveau de production situé à 1 650 mètres en dessous de la surface. Lors de la première extraction de minerai à la fin de l’année 2017, cette mine sera l’un des plus grandes et des plus profondes exploitée par foudroyage par blocs au monde. « Nous avons fait notre possible pour nous assurer que l’agrandissement soit réussi dès le départ », indiquait M. Fouche. Sous les hauts arbustes et les prairies de la célèbre région de Bushveld dans la province de Limpopo se trouvent certains des gisements les plus riches en minéraux d’Afrique, dans l’un des complexes de roches les plus dures du continent. Les exploitations minières de PMC se trouvent sur une formation de pyroxénite riche en apatite dans la région nord-est de la province ; seul le complexe du Bushveld présente des roches plus compétentes dans la région. « Les problèmes associés à l’augmentation de la production à Lift I étaient bien connus dans le secteur et concernaient le calibrage des blocs rocheux en fragments de taille permettant leur passage vers les points de soutirage », indiquait Hans-Dieter Paetzold, géologue en chef de Palabora. « Nous nous attendions à une fragmentation bien plus importante en raison de la grande résistance de la roche. » La production a atteint un maximum de 20 000 t/j en raison des goulots d’étranglement au niveau des entonnoirs de soutirage et des concasseurs car les blocs rocheux étaient trop gros. La société a fini par mandater une équipe interne d’experts en extraction et en traitement pour concevoir un système de préconcassage avec un équipement adapté afin de pouvoir augmenter la production de manière plus méthodique et prévisible. Il a fallu pratiquement deux années supplémentaires à l’exploitation pour que la production atteigne sa pleine capacité ; mais lorsque ce moment est enfin arrivé, Lift I disposait « de l’un des meilleurs systèmes de préconcassage au monde », indiquait M. Fouche. Pour ce qui est de Lift II, plutôt que de conserver la même configuration à quatre concasseurs, chacun ne disposant que d’un seul point de bascule, PMC prévoit d’utiliser deux concasseurs à cône BK 63-75 de ThyssenKrupp pouvant trai-

| profil de projet

ter 2 000 tonnes par heure (t/h). Ces concasseurs sont équipés de gueulards plus larges, ce qui leur permet de traiter du minerai plus volumineux, et de quatre points de bascule par concasseur, ce qui permet aux chargeurs-transporteurs de déverser leur chargement dans huit points de bascule différents au total. La configuration à deux concasseurs permet également d’envisager l’utilisation de chargeurs-transporteurs électriques en raison des plus courtes distances qui séparent les travers-bancs des points de bascule au centre. « L’utilisation de chargeurstransporteurs électriques nous permet de contrôler la forte chaleur qui règne dans la mine », expliquait M. Paetzold. Les températures des rochers vierges dans les profondeurs de Lift II devraient atteindre 58° Celsius, et il est important de prévoir l’empreinte au sol des véhicules électriques pour la mine afin de considérablement réduire la charge thermique globale. L’équipe du projet évalue encore les avantages possibles des chargeurstransporteurs électriques (qui affichent une meilleure capacité de refroidissement) par rapport aux machines fonctionnant au diesel (plus flexibles et plus autonomes) ou aux unités alimentées par batterie (qui requièrent des bornes de recharge).

Anticipation La configuration du préconcassage de Lift I a fini par devenir une référence pour l’industrie en matière de concassage de minerai extrêmement compétent, contrairement aux systèmes de surveillance de la caverne de l’exploitation qui n’ont jamais atteint un tel succès. « Nous ne disposions pas dès le début de programme complet de surveillance du développement de la caverne », expliquait M. Paetzold. « Nous avions bien quelques outils de surveillance et échantillons d’entonnoirs de soutirage, mais après plus ou moins huit ans, il est devenu difficile de prévoir le comportement de la caverne. » Avec seulement quelques réflectomètres temporels (TDR) dans le corps minéralisé de Lift I, le système sismique très général ne fournissait tout simplement pas suffisamment d’informations pour obtenir une vision d’ensemble de la mine à tout moment. Ainsi, la paroi nord du puits a fini par s’effondrer en 2004, après que le pilier de couronne de la caverne de Lift I se soit fendu au pied de la paroi nord de la mine à ciel ouvert. Pendant 18 mois, un glissement de près de 800 mètres par 300 s’est formé le long de la paroi depuis l’accrochage. Depuis, la dilution de jusqu’à 100 millions de tonnes de stériles dans le minerai du gisement a considérablement réduit sa teneur ainsi que la durée de vie de la mine de 5 ans. « Nous sommes maintenant conscients de l’importance de la surveillance prédictive et sommes en train d’installer un système complet pour Lift II », expliquait M. Fouche. Des TDR et des marqueurs intelligents placés dans des trous en découvert seront installés afin de couvrir la zone exploitée par foudroyage par blocs entre Lift I et Lift II. Les données collectées seront ensuite stockées et analysées à l’aide d’un logiciel GEMS. En outre, un système sismique existant est actuellement mis à niveau de manière à déterminer le moment précis auquel la caverne la plus profonde commencera à affecter les activités et l’infrastructure située au-dessus. October/Octobre 2015 | 71


Premiers travaux La vie de cette mine s’arrêtera en décembre 2015, mais la production en dehors de la caverne se poursuivra jusqu’à fin 2018 afin de réduire les pertes de réserves. La mine en activité exploitée par foudroyage par blocs se trouvant au dessus de l’espace de développement de Lift II, la société a dû élaborer une stratégie de construction afin de construire Lift II sans arrêter les activités de l’exploitation existante. Cette stratégie a donné naissance au programme de 220 millions $ dédié aux premiers travaux en 2011, lesquels impliquaient de construire des descenderies jumelées ainsi que d’améliorer le système électrique et d’aérage afin d’alimenter les exploitations Lift I et II simultanément. « Nous avons souhaité éviter une longue discontinuité des activités entre les deux exploitations étant donné que nous disposons des connaissances et de l’expérience uniques nécessaires en matière de foudroyage par blocs, et avons l’intention de conserver la compétence de la mine exploitée à l’aide de cette technique pour Lift II », indiquait M. Fouche. On remarque bien cet état d’esprit dans l’allure folle à laquelle la construction progresse et dans les nouveaux procédés et technologies qu’utilise Palabora pour y parvenir. La construction de descenderies jumelées dans l’environnement souterrain limité signifie généralement que la progression des travaux ne dépasse pas les sept mètres par jour (m/j). Cependant, la société a collaboré avec l’entrepreneur Byrnecut pour développer un procédé capable de creuser 10,5 m/j. « Plutôt que de procéder à deux déblais, un sur chaque galerie d’avancement, nous avons réussi à modifier les angles d’inclinaison des tunnels et à obtenir trois déblais dans les deux galeries chaque jour », expliquait M. Fouche. Les taux de progression ont également été maintenus en utilisant une chargeuse frontale Sandvik LH621, le plus grand modèle jamais envoyé sous terre dans un puits de mine de 1 200 mètres et la plus grosse chargeuse frontale utilisée sous terre en Afrique.

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www.cim.org 72 | CIM Magazine | Vol. 10, No. 6

L’autre engin qui contribue à l’avancement des travaux est la foreuse de montage RD8 de l’entrepreneur Master Drilling. La modélisation indique que l’agrandissement de la caverne risque d’entraîner l’effondrement des tours de ventilation actuelles, aussi « il est indispensable d’installer les premières nouvelles tours de ventilation d’ici décembre 2016, moment auquel le stade de la construction dépassera les capacités actuelles d’aérage », expliquait M. Paetzold. La société a choisi d’utiliser la méthode de forage par montage plutôt que celle, plus traditionnelle, de fonçage de puits borgnes pour développer les deux tours de ventilation de 6,1 mètres de diamètre, qui s’étendent sur 1 200 mètres entre la surface et le niveau de Lift I. La RD8 est la plus grande foreuse de montage, et la plus sophistiquée, utilisée en Afrique du Sud ; elle peut forer des trous atteignant 8,0 mètres de diamètre et 1 500 mètres de profondeur. Cette machine utilise la puissance électrique et hydraulique pour alimenter les pistons et le moteur, et elle peut être exploitée et surveillée à distance par seulement quatre personnes. Les données indiquent que les tours croiseront des structures géologiques qui peuvent présenter des problèmes pendant la phase de construction lorsqu’elles sont exposées. Cependant, la RD8 est également livrée avec le nouveau système Remote Operated Shaft Support (ROSS, un système de surveillance de la stabilité des puits commandé à distance) de l’entrepreneur, spécifiquement développé pour ce projet. Plutôt que d’attendre que le puits soit terminé et fraisé, le système ROSS permet à l’équipe d’installer à distance un système de surveillance de la stabilité du puits situé à 1 200 mètres ou moins de la machine de forage pendant le procédé de forage. « Si nous suspectons une retombée ou un glissement, nous pouvons momentanément arrêter l’alésage, raccorder le système, inspecter la zone concernée et la clôturer immédiatement », indiquait M. Paetzold. Il indiquait également que la construction des fondations était un facteur extrêmement important dans la décision. Un procédé normal de fonçage de puits borgnes implique généralement de procéder à une coupe verticale et d’entièrement creuser la zone jusqu’à ce que l’on trouve une roche appropriée pour placer les fondations. Cependant, il est possible d’installer des pieux pour soutenir des fondations avec la méthode de forage par montage, ce qui permet de considérablement réduire le temps de construction. D’après M. Paetzold, la construction du premier des deux puits, sur lequel PMC travaille depuis mars, sera terminée d’ici la fin de l’année 2016. « Les deux puits seront construits bien plus rapidement que si nous avions décidé de foncer un seul puits borgne de huit mètres de diamètre, et cette solution sera également bien moins onéreuse. » Le développement de Lift II devrait prolonger la durée de vie de la mine jusqu’en 2033, et cette fois-ci, l’équipe de Palabora est convaincue qu’elle partira sur de bonnes bases. « La technique de foudroyage par blocs est une option unique que l’on apprend avec le temps et en acquérant l’expérience nécessaire », indiquait M. Fouche. « Nous avons cette grande chance d’avoir pu la parfaire dans le cadre de notre deuxième projet. » ICM


An Introduction to Cutoff Grade: Theory and Practice in Open Pit and Underground Mines (with a new section on blending optimization strategy) Cut-off grades are essential in determining the economic feasibility and mine life of a project. The fundamentals of cut-off grade calculation, first established by Ken Lane forty years ago, are revisited. In this course it is shown how direct and indirect costs, opportunity costs imposed by operational constraints, and other factors, such as political risk, legal, environmental and regulatory requirements, must be taken into account. Mathematical equations are developed and graphical analytical methods are displayed, which can be used to solve most cut-off grade estimation problems. It is shown how minimum cut-off grades are estimated and how they must be modified to take into account constraints imposed by mine or mill capacity, or by limits on sales volumes. Multiple practical examples are given, illustrating the role of cut-off grades in mine planning, in allocating material to different processes, in optimizing mill operating conditions, and in poly-metallic deposits.

INSTRUCTOR Jean-Michel Rendu, JMR Consultants, USA • DATE Returning in 2016 • LOCATION Montreal, Quebec, Canada

Geostatistical Mineral Resource Estimation and Meeting the New Regulatory Environment: Step by Step from Sampling to Grade Control This course is designed according to the latest regulations on public reporting of Mineral Resources. It aims at showing how state-of-the-art statistical and geostatistical techniques help answering the requirements of those regulations in an objective and reproducible manner. A particular emphasis is put on understanding sampling and estimation errors and how to assign levels estimation confidence through the application of resource classification fundamentals. In addition to a solid introduction to mining geostatistics this course provides a comprehensive overview of industry’s best practices in the broader field of Mineral Resource estimation.

INSTRUCTORS Marcelo Godoy, Newmont Mining Corp., Denver; Jean-Michel Rendu, JMR Consultants, USA; Roussos Dimitrakopoulos, McGill University, Canada; and Guy Desharnais, SGS Canada Inc., Canada • DATE Returning in 2016 • LOCATION Montreal, Quebec, Canada

Optimization and Risk Management in Strategic Mine Planning: Unearthing Material Value in Mining Complexes Growing volatility and uncertainty in global metal markets highlight the need to focus on new technologies that can unveil significant value and reliability to the performance of mining operations. This three-day course explores the foundations of strategic mine planning and stresses the new generation of applied technologies related to: (a) simultaneous optimization of integrated mining and processing operations, and (b) orebody risk management with new stochastic mine planning optimization developments.

INSTRUCTORS Roussos Dimitrakopoulos and Ryan Goodfellow, McGill University, Canada; and Brian Lambert, Minemax, USA • DATE Returning in 2016 • LOCATION Montreal, Quebec, Canada

Quantitative Mineral Resource Assessments: An Integrated Approach to Planning for Exploration Risk Reduction Learn about exploration risk analysis for strategic planning. Understand how to demonstrate how operational mineral deposit models can reduce uncertainties; make estimates of the number of undiscovered deposits; and integrate the information and examine the economic possibilities. INSTRUCTOR Don Singer, USA • DATE Returning in 2016 • LOCATION Montreal, Quebec, Canada


TECHNICAL ABSTRACTS

CIM

journal

Excerpts taken from abstracts in CIM Journal, Vol. 6, No. 4. To subscribe, to submit a paper or to be a peer reviewer—www.cim.org

Mixed spectral study of hyperspectral data for abundance estimation of ores in Gua iron ore mines, India S. Patteti, B. Samanta, and D. Chakravarty, Department of Mining Engineering, Indian Institute of Technology, Kharagpur, India; and D. Dutta, Regional Remote Sensing Centre-East (NRSC), Indian Space Research Organisation, New Town, Kolkata, India

ABSTRACT This paper presents the mixed spectral behaviour of iron ores from deposits in Gua, India. Spectral signatures of powder samples and their two-component mixtures were generated by spectroradiometry. Spectra were divided into continuum and absorption components. A modified Gaussian model was used to extract subtle features from the absorption components of the spectra. A linear unmixing model (LUM) applied to estimate minerals from the spectra of mixed powder samples indicated that this model achieved an R2 value of 0.88. The LUM was then applied to estimate the abundance of ores from a hyperspectral satellite image of the deposit area.

RÉSUMÉ Le présent article montre le comportement spectral mixte de minerais de fer de gisements à Gua, en Inde. Les signatures spectrales d’échantillons de poudres et leurs mélanges à deux composantes ont été générés par spectroradiométrie. Les spectres ont été divisés en composantes de continuum et d’absorption. Un modèle gaussien modifié a été utilisé pour extraire des caractéristiques subtiles des composantes d’absorption des spectres. Un modèle de démélange linéaire, appliqué pour estimer les minéraux dans le spectre des échantillons de poudres mixtes, indique que ce modèle a atteint une valeur R2 de 0,88. Le modèle de démélange linéaire a ensuite été appliqué pour estimer la quantité de minerai à partir d’une image satellite hyperspectrale du secteur du gisement.

Successful application of a diesel particulate filter system at Vale’s Creighton mine J. S. Stachulak, MIRARCO Mining Innovation, Sudbury, Ontario, Canada; C. Allen, Vale Mining & Milling Technology, Copper Cliff, Ontario, Canada; and V. Hensel, Formerly MANN+HUMMEL GmbH, Ludwigsburg, Germany

ABSTRACT Vale has been actively evaluating new technologies to curtail diesel emissions. This paper discusses the selection, installation, operation, and evaluation of the MANN+HUMMEL SMF®-AR diesel particulate filter system to reduce diesel particulate matter emissions in underground mines. The system uses a sintered metal filter element, an iron fuelborne catalyst with an onboard dosing system, an electric heater that uses onboard power, and a sensor-based control unit. More than 6,000 h of testing demonstrated that the system represents a breakthrough in the successful control of soot emission from light-duty vehicles with differing soot emission levels, exhaust temperatures, and duty cycles.

RÉSUMÉ La compagnie Vale évalue activement de nouvelles technologies pour réduire les émissions de diesel. Le présent article discute du choix, de l’installation, du fonctionnement et de l’évaluation du système MANN+HUMMEL SMFMD-AR de filtrage des particules de diesel pour réduire les émissions de particules de diesel dans les mines souterraines. Le système utilise un élément filtrant en métal fritté, un catalyseur à base de fer dans le carburant avec un système de dosage intégré, un élément de chauffage électrique qui utilise l’alimentation incorporée et une unité de contrôle avec un capteur. Plus de 6 000 heures d’essais ont démontré que le système représente une avancée pour réussir à contrôler les émissions de suie des véhicules légers avec différents niveaux d’émission de suie, différentes températures d’échappement et différents cycles opératoires.

Les mines et le développement durable : controverses et défis N. Bensalah, D. Ferrand, et C. Villeneuve, Université du Québec à Chicoutimi, Chicoutimi, Québec, Canada

RÉSUMÉ La conciliation entre l’expansion de l’industrie minière et les exigences du développement durable représente un grand défi. Face aux différentes controverses touchant cette industrie, la dernière décennie a été marquée par une plus grande mobilisation de l’ensemble des parties prenantes. Cependant, plusieurs carences persistent en matière d’opérationnalisation du concept de développement durable. Ce défi met en cause la responsabilité partagée entre les parties prenantes. Il exige le renforcement des responsabilités gouvernementales et l’instrumentalisation de bonnes pratiques de responsabilité sociale des entreprises. En aval, s’impose la gestion intégrée de l’usage des produits miniers et la promotion de l’innovation et de la recherche.

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ABSTRACT Conciliation between expansion of the mining industry and sustainable development requirements represents a great challenge. With regard to the various controversies touching this industry, the last decade was marked by a great mobilization phase of all stakeholders. However, there are still many shortcomings regarding operationalization of the sustainable development concept. This challenge involves shared responsibility between the stakeholders. It requires strengthening government accountability and instrumentalization of good corporate social responsibility practices. Further down the chain, the use of mining products and the promotion of innovation and research must be achieved through integrated management.


TECHNICAL ABSTRACTS

CIM

journal

Excerpts taken from abstracts in CIM Journal, Vol. 6, No. 4. To subscribe, to submit a paper or to be a peer reviewer—www.cim.org

Analyzing energy consumption and gas emissions of loading equipment in underground mining A. Salama, J. Greberg, B. Skawina, and A. Gustafson, Department of Civil, Environment and Natural Resources Engineering, Division of Mining and Rock Engineering, Luleå University of Technology, Luleå, Sweden

ABSTRACT In an environment of rising energy prices and mining at greater depths, cost-efficient loading and hauling equipment is essential. Conducted at an underground mining operation, this study analyzes the energy consumption and gas emissions of diesel and electric load-haul-dump machines (LHDs) with similar bucket capacities. Based on current energy prices, results of discrete event simulation show that energy costs for diesel and electric LHDs are US$0.24/t and US$0.07/t, respectively. Also, diesel LHDs emit 2.68 kg CO2 per litre of diesel fuel, whereas using electric machines reduces the need for ventilation to mitigate engine heat and emissions and reduces energy costs.

RÉSUMÉ Dans un contexte de croissance des prix de l’énergie et d’exploitation minière à des profondeurs de plus en plus grandes, il est essentiel d’avoir des équipements de chargement et de transport les plus rentables possible. La présente étude, effectuée dans une mine souterraine, analyse la consommation énergétique et les émissions de gaz de chargeuses-navettes (LHD) au diésel et à l’électricité ayant des capacités de godet similaires. En se basant sur les prix courants de l’énergie, les résultats d’une simulation d’événements discrets montrent que les coûts énergétiques pour les LHD au diésel et à l’électricité sont respectivement de 0,24 $US/t et de 0,07 $US/t. De plus, les LHD au diésel émettent 2,68 kg CO2 par litre de combustible diésel alors que les machines utilisant l’électricité réduisent le besoin de ventilation pour atténuer la chaleur des moteurs et les émissions en plus de réduire les coûts énergétiques.

Promoting transparency in Central African mineral development C. Nwapi, Canadian Institute of Resources Law, Faculty of Law, University of Calgary, Calgary, Alberta, Canada; A. Ingelson, Canadian Institute of Resources Law, Faculty of Law, University of Calgary, Calgary, Alberta, Canada (and Haskayne School of Business, University of Calgary, Calgary, Alberta, Canada)

ABSTRACT With growing international interest in mineral resources in Central Africa, the importance of transparency in resource development cannot be overemphasized. Without transparency, the region cannot maximize revenues from resources. Although the importance of transparency is beginning to be recognized, many factors can hold back the gains of transparency from resulting in real economic development for the countries involved. This paper reviews current financial, economic, and development literature for Central African countries, with a focus on identifying underlying conditions and specific transactional conditions impacting the effectiveness of transparency in mining development in the region.

RÉSUMÉ En raison de l’intérêt international croissant pour les ressources minérales en Afrique centrale, l’importance de la transparence dans le développement des ressources ne peut pas être surestimée. Sans transparence, la région ne peut pas maximiser les revenus tirés de ses ressources. Bien que l’importance de la transparence commence à être reconnue, plusieurs facteurs peuvent freiner les gains acquis de la transparence à produire un véritable développement économique pour les pays touchés. Le présent article analyse la littérature financière, économique et développementale contemporaine pour les pays de l’Afrique centrale, tout en ciblant l’identification des conditions sous-jacentes et les conditions spécifiques transactionnelles qui ont un impact sur l’efficacité de la transparence dans le développement minier de la région.

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TECHNICAL ABSTRACTS

canadian metallurgical quarterly

Excerpts taken from abstracts in CMQ, Vol. 53, No. 1. To subscribe – www.cmq-online.ca

Extractive metals from metallic powders recovered from waste printed circuit boards

P. Zhu; Z. B. Cao, G. R. Qian, Y. Sun, Q. Liu, Z. Y. Fan, College of Environmental and Chemical Engineering, Shanghai University, Shanghai and Key Laboratory of Solid Waste Treatment and Resource Recycle (SWUST), Ministry of Education, China; and M. Zhou, Semiconductor Manufacturing International (Shanghai) Corporation, Shanghai, China

ABSTRACT Leaching behaviours of metallic powders were investigated using electrically generated chlorine at the anode chamber containing sulphuric acid solution, NaCl and CuSO4. Various parameters, which included the solid/liquid ratio, current density, concentration of NaCl, CuSO4, and H2SO4, leaching temperature, particle size, and stirring speed, were studied to understand the mechanism of leaching metallic powders. The capability of dissolved metallic powders increased with the increase in all parameters except the solid/liquid ratio. Leaching metallic powders were transportcontrolled with a low activation energy of 14.7 kJ mol−1. The dissolved copper could be transferred from the anodic chamber to the middle chamber by solvent extraction technology. In the electric field, copper ions are transferred from the middle chamber to the cathodic chamber through a cation exchange membrane (CEM) and electrodeposited to form copper foils. The tensile strength and elongation percentage of 65 m-thick copper foils were 276 MPa and 10.66%, respectively. The utilisation of metallic powders recovered from waste PCBs (WPCBs) could produce high-performance copper foil.

RÉSUMÉ On a examiné le comportement de lixiviation de poudres métalliques en utilisant du chlore engendré par électricité dans la chambre de l’anode contenant une solution d’acide sulfurique, du NaCl et du CuSO4. On a étudié une variété de paramètres, incluant le rapport solide à liquide, la densité de courant, la concentration de NaCl, de CuSO4 et d’H2SO4, la température de lixiviation, la taille de particule et la vitesse d’agitation, afin de comprendre le mécanisme de lixiviation des poudres métalliques. La capacité des poudres métalliques dissoutes augmentait avec l’augmentation de tous les paramètres, sauf le rapport solide à liquide. Les poudres métalliques de lixiviation étaient contrôlées par le transport, avec une faible énergie d’activation de 14,7 kJ/mo-1. On pouvait transférer le cuivre dissous de la chambre anodique à la chambre du milieu au moyen de la technologie d’extraction par solvant. Dans un champ électrique, les ions de cuivre étaient transférés de la chambre du milieu à la chambre cathodique par une membrane d’échange de cation et étaient déposés par galvanoplastie pour former des feuilles de cuivre. La résistance à la traction et le pourcent d’élongation de feuilles de cuivre de 65 m d’épaisseur étaient respectivement de 276 MPa et de 10,66 %. Les poudres métalliques récupérées de cartes de circuit imprimé de rebut pourraient produire une feuille de cuivre à haute performance.

Uptake of Zn2+ from dilute aqueous solutions using protonated dry alginate beads J. P. Ibáñez, Departamento de Ingeniería Metalúrgica y de Materiales, Universidad Técnica Federico Santa María, Valparaíso, Chile; and A. Aracena, Escuela de Ingeniería Química, Pontificia, Universidad Católica de Valparaíso, Valparaíso, Chile

ABSTRACT The uptake of zinc ions from dilute aqueous solutions was studied at 25 °C using protonated dry alginate beads (PDAB) of around 1 mm in diameter. The Zn2+ uptake increases with the pH of the Zn bearing solution, reaching a value of around 90 mg of Zn per gram of beads (dry weight) at pH 4·5. For an initial Zn concentration as low as 10 mg L−1, the removal reached was complete. The mechanism of Zn uptake was found to be ion exchange between zinc ions and protons form the functional groups of the beads, which followed a pseudo-second order kinetic behaviour. In equilibrium condition the experimental data followed the Langmuir adsorption model. The maximum uptake reached were around 145 and 165 mg g−1 at pH values of 3.5 and 4.5, respectively, which is higher than most of the sorbents used for zinc removal. EPMA-EDX analysis shows that the functional groups of the PDAB were homogeneously distributed during preparation of beads, and that zinc ions were able to reach functional groups in the entire structure of the beads without a concentration gradient across the beads.

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RÉSUMÉ On a étudié le changement d’ions de Zinc depuis des solutions aqueuses diluées à 25 °C en utilisant des sphères protonadas sèches d’alginatos (PDAB) d’autour de 1 mm de diamètre. Le changement de Zn2+ augmente avec le pH de la solution, en atteignant une valeur d’autour de 90 mg de Zn par gramme de sphères (un poids sec) à un pH 4,5. Pour un concetración initial de Zn plus bas que 10 mg L-1, le changement à court d’argent a été complet. Le mécanisme de changement de Zn est été par un échange ionique entre des ions de zinc et protones provenants depuis les groupes fonctionnels des sphères, qui a un comportement cinétique du pseudo-deuxième ordre. Dans des conditions d’équilibre, les données expérimentales suivent un modèle d’adsorpcion de Langmuir. Le changement maximal à court d’argent a été de 145 et 165 mg g–1 aux valeurs de pH de 3,5 et 4,5, respectivement, où elles ont été plus hautes que les sorbentes utilisés pour le changement de Zn. Des analyses par EPMA-EDX ont montré que les groupes fonctionnels du PDAB ont été distribués de façon homogène durant la préparation des sphères, et que les ions de zinc ont été capables d’atteindre les groupes fonctionnels dans toute la structure des sphères sans une pente de concentration à travers des sphères.


TECHNICAL ABSTRACTS

canadian metallurgical quarterly

Excerpts taken from abstracts in CMQ, Vol. 53, No. 1. To subscribe – www.cmq-online.ca

Effect of prior heat treatment on wear behaviour of 0.23% carbon dual phase steel S. Bhowmick, Durgapur Steel Plant, Durgapur, West Bengal, India; and B. K. Show, Department of Metallurgical and Materials Engineering, National Institute of Technology, Durgapur, West Bengal, India

ABSTRACT The present study is aimed at understanding the effect prior heat treatment on the high-stress abrasive wear response of 0.23% carbon dual phase steel. Asreceived steel was subjected to annealing, normalising and hardening treatment prior to actual dual phase heat treatment. These steels along with the as-received steel were intercritically annealed at 745 °C followed by water quenching in order to produce dual phase microstructures. Abrasion tests were carried out at varying sliding distances with a 40 m abrasive and at 7 N applied load. Wear test at varying loads were also performed for the steel that showed maximum wear resistance. Dual phase treatment resulted in improved overall wear response. The wear resistance for the steel with prior annealing treatment (DPLA-1) and for the steel with prior hardening treatment (DPLA-3) improved over the entire range of sliding distance. It was also found that the wear rate increased with applied load for DPLA-1 steel.

RÉSUMÉ Cette étude vise à comprendre l’effet du traitement thermique antérieur sur la réponse à l’usure par abrasion à contrainte élevée de l’acier biphasé à 0,23% de carbone. On a soumis l’acier brut d’usinage à un traitement de recuit, à un traitement de normalisation ainsi qu’à un traitement d’endurcissement avant le traitement thermique actuel de structure biphasée. On a effectué un traitement de recuit intercritique à 745 °C de ces aciers ainsi que de l’acier brut d’usinage, suivi par trempe à l’eau afin de produire des microstructures biphasées. On a effectué un essai d’abrasion sur des distances variées de glissement avec un abrasif de 40 m et une charge appliquée de 7 N. On a également effectué un essai d’usure avec diverses charges de l’acier ayant montré la meilleure résistance à l’usure. Le traitement de structure biphasée améliorait globalement la réponse à l’usure. L’acier avec traitement de recuit antérieur (DPLA-1) ainsi que l’acier avec traitement d’endurcissement antérieur (DPLA-3) ont montré une amélioration sur toute la gamme de distance de glissement. La vitesse d’usure de l’acier DPLA-1 augmentait avec l’application de la charge.

Mechanical behaviour of thermomechanically produced ultrafine grained dual-phase steels R. González, School of Engineering, Universidad Panamericana, Ciudad de México, Distrito Federal, Mexico; J. O. García, L. F. Verdeja, E.T.S.I.M.O., Universidad de Oviedo, Oviedo, Spain; M. J. Quintana, School of Engineering, Universidad Panamericana, Ciudad de México, Distrito Federal, Mexico; and J. I. Verdeja, E.T.S.I.M.O., Universidad de Oviedo, Oviedo, Spain

ABSTRACT Dual-phase (DP) steels are an excellent alternative in the production of automotive parts that require high mechanical resistance, high impact strength and elevated elongation. These materials are produced using low alloy steels as a basis, reducing costs and resulting in a combination of martensite and ferrite structures with ultrafine grain size. These characteristics are achieved through strict control of rolling conditions, strain rate, cooling rate and coiling temperature. This work presents the results of tension testing of two types of DP steels, along with microstructural characterisation, in order to understand the effect of the advanced thermomechanical controlled rolling processes on the formation of the microstructure and resulting mechanical properties.

RÉSUMÉ Les aciers biphasés sont une excellente substitution pour la production de composantes automobiles qui requièrent une résistance mécanique élevée, une haute résistance à l’impact et une grande élongation. Ces matériaux sont produits en utilisant des aciers faiblement alliés comme base, réduisant les coûts et engendrant des combinaisons de structures martensitiques et ferritiques à granularité ultrafine. On obtient ces caractéristiques grâce à un contrôle strict des conditions de laminage, de la vitesse de déformation, de la vitesse de refroidissement et de la température d’enroulement. Cet article présente les résultats des essais de traction de deux nuances d’acier biphasé, de même que la caractérisation de la microstructure, afin de comprendre l’effet des procédés avancés de laminage thermomécanique contrôlé sur la formation de la microstructure et les propriétés mécaniques qui en déroulent.

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TECHNICAL ABSTRACTS

canadian metallurgical quarterly

Excerpts taken from abstracts in CMQ, Vol. 53, No. 1. To subscribe – www.cmq-online.ca

A comparison of hydrogen permeation and the resulting corrosion enhancement of X65 and X80 pipeline steels X. Y. Peng, College of Petroleum Engineering, Southwest Petroleum University, Chengdu, Sichuan, China; and Y. F. Cheng, Department of Mechanical and Manufacturing Engineering, University of Calgary, Calgary, Alberta, Canada

ABSTRACT In this work, corrosion and electrochemical hydrogen permeation behaviour of two grades of pipeline steel, X65 and X80 steels, were investigated by hydrogencharging, electrochemical impedance spectroscopy measurements and metallographic observation. It was found that the corrosion and hydrogen permeation behaviour of steels is affected by their metallurgical features. Upon hydrogen-charging, both high grade of X80 pipeline steel and low grade of X65 steel show enhanced corrosion activity. The electrochemical hydrogen permeation current measurements and calculations show that the X80 steel contains a higher density of hydrogen traps than X65 steel, which may potentially result in the increased susceptibility of X80 steel to hydrogen-induced cracking (HIC).

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RÉSUMÉ Ces travaux ont étudié le comportement à la corrosion et à la perméation électrochimique de l’hydrogène de deux grades d’acier utilisés pour la construction de pipelines, X65 et X80, à l’aide du préchargement à l’hydrogène, de mesures par spectroscopie de l’impédance électrochimique et d’un examen métallographique. On a constaté que le comportement des aciers à la corrosion et à la perméation de l’hydrogène est affecté par leurs propriétés métallurgiques. Durant le préchargement à l’hydrogène, l’acier à haute limite d’élasticité de grade X80 utilisé pour la construction de pipelines et celui à basse limite d’élasticité de grade X65 affichent tous deux une meilleure activité corrosive. Les mesures et calculs actuels de la perméation électrochimique de l’hydrogène montrent que l’acier de grade X80 contient une plus forte densité de piégeage de l’hydrogène que l’acier de grade X65, ce qui pourrait se traduire par une plus forte susceptibilité de X80 au phénomène de fissuration induite par l’hydrogène (HIC).


innovation showcase | ad index ADVERTISERS 51 37 45 20 29 38 39 50 32 OBC 17 30 IFC 27 7 4 11 41 13 43 9 19 25 21 26 IBC 3 24 53 57 79

ALS Global Amalgamated Mining AMC Consultants AMEC Foster Wheeler American Peat Technology BKT Tires Canada Inc. Cementation Coast Automation DMC Mining Services Dumas Mining Endress+Hauser Eriez Manufacturing Co. FLSmidth Golder Associates Ltd. Hatch HLS Hard-Line Solutions J.H. Fletcher & Co. Joy Global Maptek Pentair Flow Technologies Petro-Canada RDH Mining Equipment Ltd Redpath Group Rousseau Metal Inc. SNC-Lavalin SSAB Telsmith, Inc. Tsubaki of Canada Limited Wajax Equipment XPS - A Glencore Company

RDH After the success of its 3 cubic yard battery powered LHD and its 20 tonne battery powered haul truck, RDH is introducing a larger, more powerful underground loader to its Evolution battery equipment line, the Muckmaster 600EB, the world’s first 6 yard capacity battery powered LHD for hard rock. Reduced costs, a healthier work environment, and increased production are but a few of the benefits the technology over diesel machinery. Nearly 5 years of testing has provided the RDH team with knowledge that only working underground can provide. In keeping with their guiding design principle, “simplifying heavy equipment”, RDH has simplified and improved the battery system, ensuring a product that is more economical and easier to operate and maintain. The Muckmaster 600EB has the same dimensions as the company’s standard 6 yard diesel loader and all of the features. It has a charging time of 2 hours, a battery management system (BMS) and a 400 amp LiFePO4 battery pack. Benefits of LiFePO4 battery technology; tolerant to abuse, extremely stable in overcharge or short circuit conditions, able to withstand high temperatures, not prone to thermal runaway, will not burn, does not contain heavy metals, does not exhibit “memory effect”, excellent shelf life, long cycle life, maintenance free, no “voltage sag”, and can be safely rapidly recharged.

Innovation showcase RDH Mining Equipment

IN THE NEXT ISSUE SPECIAL REPORT: GREENLAND The land is rich in mineral deposits and the government is motivated to ramp up mining

AFTER MOUNT POLLEY, MINERS CONSIDER TAILINGS STORAGE ALTERNATIVES

Courtesy of North American Nickel

MILLING A conversation with CEEC International director and Advisian principal process engineer Zeljka Pokrajcic

• TECHNOLOGY The assaying power of cross-belt analyzers

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T

By Lindsay Seegmiller

STAY

Park Inn by Radisson Tete

WHERE TO

ete (pronounced “tet”) is well known for its abundance of coal and scorching (35 to 40+ degrees Celsius) temperatures. The city is the capital of a province of the same name, which is located in Mozambique’s western arm, hugged by Malawi, Zambia, and Zimbabwe. Expanding out over a high plateau bisected by the Zambezi River, Tete was, for many years, a quiet and forgettable place. Since Vale green-lighted a massive expansion to its local metallurgical coal mining project in 2011, however, Tete has experienced rapid commercial development, racing to meet the startling influx of foreign companies, expatriates and migrating regional workers. Four years later, the province’s population has tripled to more than 1.8 million, Tete’s amenities rival the national capital, Maputo, and there are few signs of decelerated growth. Of course, relative to global mining towns Tete feels distinctly exotic. Power outages, colourful local politics and dusty roads remind visitors of a more remote lifestyle and a not-so-distant civil war. Flexibility and patience will go a long way here.

DINE

TIP

Park Inn by Radisson Tete

WHERE TO

In spite of Tete’s rapid commercial development, business-style accommodation remains decidedly scarce. The Park Inn by Radisson (US$130-180 per night) is the unrivalled leader for business travellers. With 117 suites serviced by wireless network (WiFi), a conference room, a Western-style restaurant, a fitness centre and a pool, it is unsurprising that expatriates flock to this air-conditioned space. That said, the VIP Executive Tete Hotel (US$160+) opened in the spring. The newest addition to the Portuguese hotel chain, the VIP Executive offers a

swimming pool, WiFi, meeting rooms, a restaurant, two bars and a 24-hour business centre. Outside these choices, options are much more basic, offering little more than a bed, a table, linens and a lamp. Prices drop to under US$100/night, proportional to the quality of amenities and services. For a reprieve from Tete’s hectic city centre, consider Villa Hapsburg. This German-owned B&B (US$150-200) offers serenity on the banks of the Zambezi and an atmosphere that is all but lost in the heat of the city.

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Voce fala Português? As a former Portuguese colony, Mozambique’s national language is Portuguese. Though the business and tourism communities are largely English speaking, basic familiarity with the language is an asset. The Park Inn’s RBG Bar & Grill holds a virtual monopoly on fine dining in town. Open daily and serving a variety of Western dishes (sandwiches, burgers, pastas, chicken, beef, pork and curries), RBG feels happily

TIP

Prioritize air conditioning! It’s not uncommon for temperatures to surpass 40 C in Tete at any time of year.

familiar. For a more local experience, Café del Rio on the banks of the Zambezi offers simpler Western fare, cold beer and a spectacular view. Popular with expatriates and business travellers, Café del Rio fills up quickly around sunset. For those keen to venture beyond the carefully contained Western air-conditioned refuges, Mozambique offers a world of Portugueseinspired flavours inside small streetside shops and stalls. The country is known

Nicolette Killoran

Tete, Mozambique

Steve Conover

TRAVEL

for its fiery Piri Piri hot sauce, often served alongside a medio frango – a roasted half chicken. Paired with a chilled 2M or Manica – the local beers of choice – and a fresh bread roll, this meal is arguably Mozambique’s most satisfying.


Drive an hour outside Tete and the energy of the boomtown subsides as baobabs reemerge along the horizon. The prime provincial attraction is the Cahora Bassa, Africa’s second largest dam, fourth largest lake and arguably its best and least-visited fishing destination. Tiger fish are of primary interest, though bird watching and hiking are equally as pleasant. Local lodges, such as Moringa Bay or Ugezi Tiger Lodge, provide full fishing gear, a guide and a boat, along with catered and self-catered accommodation.

HOW TO

PAY

Mozambique’s currency is the New Metical (MZN, M), and it trades at around 30M to one Canadian dollar. Though the Radisson will accept credit cards and American cash, virtually all

TIP

other establishments will expect to be paid in the local currency and in cash. Most ATMs in Tete accept international cards; however, they have a frustrating tendency to run low on cash.

Always keep some extra cash – USD or M – tucked away, in the event that ATMs run out of money. American dollars can be traded for MZN at local banks. Avoid bringing traveller’s cheques as they are often difficult to exchange.

TIP For much of the year, Tete is hot and arid. However, there is a rainy season between December and March, during which humidity levels climb but temperatures do not drop. Martha Evans

EXPLORE

Within Tete, attractions are limited. Architectural remnants of Portuguese colonial rule are visible, though signs of civil war-instigated dilapidation are more obvious. The Samora Machel suspension bridge over the Zambezi is a local landmark, given its total length of more than 750 metres in a country of otherwise basic infrastructure. Wikimedia

WHERE TO

When the heat becomes too oppressive inland, Mozam-

bique’s twinkling ocean shoreline is a short flight or two away. Consider a weekend getaway to Pemba or Vilankulo, where you can lose yourself in the pristine and luxurious Quirrimbas and Bazaruto archipelagos.

GETTING

AROUND

Tete is best navigated by taxi or private vehicle. Europcar and Sixt both have offices at the airport for short- and longterm rentals. Alternatively, unmetered taxis are readily accessible and visitors should be prepared to negotiate with drivers prior to departing. You might start by trying to pay half of their initial quote. Public transit is an option, but it is difficult and dangerous to navigate. Tete is serviced by Chingozi airport, with connecting flights to South Africa (Johannesburg) and major Mozambican cities (Maputo, Beira, Lichinga, Nampula, and Quelimane).

Wikimedia

Teresa Cotrim

Beyond that, an extremely popular activity is seeking refuge from unforgiving heat in hotel swimming pools, accessible by nonguests for a small fee.

October/Octobre 2015 | 81


A tale restored from the slag pile By Katelyn Spidle

E

82 | CIM Magazine | Vol. 10, No. 6

Flickr/André Carrotflower

merging from his The last two buildings quarters one day housed the first production in AD 1000, Vikof iron in the New World. ing explorer Leif Eriksson Vikings were keen metallurfinally saw what he had gists, and most explorers sailed across the North and settlers had at least a Atlantic in search of: a rudimentary knowledge of rocky shoreline looming how to locate and produce in the distance. His 30bog iron. They would smelt man crew furled the the ore in a small, clay-lined ship’s sail, dropped ancylindrical furnace, known chor and rowed to the as a bloomery. Once the shores of present-day smelting process was comNewfoundland. plete, the iron was then Writings and oral hisforged in a smithy. tories passed down from Archaeological remains the Viking Age tell that Viking explorers constructed eight buildings at present-day L’Anse Aux Meadows, of the buildings were disNewfoundland in AD 1000, two of which were used to produce iron from nearby wetlands. growing populations and covered almost a thousand tensions between clans years later and would act as caused the Norse people to expand westward from Scandi- proof of pre-Columbian European contact with North Amernavia over a period of more than 250 years. They crossed the ica. Today, the site holds UNESCO World Heritage status and Scottish Isles and Faeroe Islands before colonizing Iceland. is named L’Anse Aux Meadows. In seven separate digs between Eventually, Erik the Red, Eriksson’s pioneering father, led a 1961 and 1968, archaeologists Helge Ingstad and Anne Stine series of voyages that resulted in the colonization of Greenland. Ingstad found 15 kilograms of slag, which is thought to have The settlements thrived, but unfortunately, the land turned out produced about three kilograms of usable iron. However, to be low in key natural resources like lumber and iron. analysis of the slag revealed that it would have been possible The purpose of Leif Eriksson’s western voyage had been to to extract considerably more iron from the ore. This suggested locate lumber and animal pelts. At the time, the North Atlantic that Eriksson’s men were not particularly skilled compared to was experiencing a period of warm climate, and the forest in other metallurgists from the Viking Era. Newfoundland was dense with tall trees and wild game. He Nonetheless, Eriksson and his crew would have had a more would return to Greenland that autumn transporting plenty of advanced knowledge of these processing techniques than abomaterials to trade and sell. While exploring the lush fields riginals in North America. Found in glaciated regions across along the coast, Eriksson came across a curious fruit that was the globe, bog ore was an incredibly valuable natural resource growing wildly across the region: grapes. The discovery would for the Norse who used it to make tools, armour and weapons. inspire him to name the area Vinland. It is for this reason that Thorfinn Karlsefni – an Icelandic Here, Eriksson’s party set up a summer base camp. Off in explorer who led a subsequent journey to Newfoundland – the distance, mountain springs descended into a large freshwa- refused to trade the precious metal with the Beothuk First ter lake before being funnelled through a winding stream that Nation he encountered. At that time, the now-extinct Beothuk snaked around and flooded a rich peat bog. The Vikings rec- peoples carved bone and wood to make tools and weaponry. ognized the characteristics of the landscape and identified the L’Anse Aux Meadows never became a permanent Viking presence of iron in the wetlands. settlement. It is impossible to determine exactly how long the The crew erected eight buildings immediately west of the camp was used, and there are several theories that the Vikings iron-rich peat bog. The largest – at 28.8 by 15.6 metres – may have explored the Canadian Maritimes further and the served as the captain and crew’s sleeping quarters. Three oth- northeast coast of the United States. To date, L’Anse Aux Meaders contained small woodworking sheds and even smaller ows contains the only confirmed physical proof – consisting of rooms for slaves. A fifth housed a large woodworking and tex- 98 nail fragments, countless rivets, and other assorted artifacts tiles shed; the sixth became a ship repair shop where archeol- scattered throughout the site – of a Viking presence in North ogists would later locate rivets and nails. America. CIM


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CIM Magazine October 2015  

COVER STORY: A new generation of ore sorting PLUS stories on underground mining and process monitoring

CIM Magazine October 2015  

COVER STORY: A new generation of ore sorting PLUS stories on underground mining and process monitoring