Mining Magazine October 2014

Page 1

The mining industry’s leading magazine

Established

1909

Surface miners

Get the most from your surface miner fleet. MM reviews performance-enhancing technologies and aids

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Engines & drives

The global market for truck engine repowers is hotting up. MM visited ASARCO’s Ray mine in Arizona to find out how the operation is saving money and making significant fuel cost-savings

Underground development

Learn about the latest advances in rapid development and hard-rock cutting, shaft sinking, raise boring and tunnel boring

October 2014

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CONTENTS

1

Finnish focus

M

ineral-processing company Metso is about to undergo its second major restructure in 12 months. The company demerged its pulp, paper and power business units into a standalone company, Valmet Corp, in December 2013.

In an interview at the time, president and CEO Matti Kähkönen told me that heightened focus within customer industries was a key driver. He also wanted to leverage synergies within Metso’s business units to deliver more intelligent solutions and better product-related services to clients. It seems that a year on, this vision stills holds. In an interview at the company’s Helsinki headquarters in August, Kähkönen described the new structure, which was announced in July and will come into effect on October 1, as well as its implications. Designed to streamline Metso and focus its growth on higher-margin businesses, the new strategy divides the company into three business areas: Flow Control, which will offer valves for the oil & gas sector and pumps for the mining industry; Minerals, which will offer products to the mining and aggre“We have a good gates sectors; and Services, which will cater to customers in strategy and all the both mineral processing and flow control.

News

2

Features Special report: Hitachi in Israel

6

Special report: mobile computing

10

Special report: Weir Minerals

12

Column: Futurecasting

16

Mine of the month: Drakelands

18

tools, people and “We have split the capital and projects side of our offerings and the services side,” said Kähkönen, “Both now report technologies we need directly to me. We want to emphasise the importance of to truly believe that it services even more. Even though the mining industry isn’t will create more value” investing much in capital projects at the moment, mining services which are related to production are growing. That’s going well and we expect to see significant growth in the next year.”

Engines & drives

23

Surface miners

36

Snapshot

42

SX-EW

44

Underground development

50

Physical separation

60

As part of the strategy, Metso is also exploring options for its process-automation business, which supplies the pulp and paper industry. “Those technologies are very specific to that industry; they can’t be used in oil & gas or mining, so we have decided to evaluate alternative options including divestment,” explained Kähkönen. “We haven’t made a decision yet but we should know by the end of the year.”

Water management

66

Flashback & contacts

71

Classified advertising

72

It is interesting that, at a time when many companies are looking to diversify to safeguard against weakened markets, Metso has chosen to narrow its industry focus. However, Kähkönen is confident that the move is a positive one. “In 2013 we evaluated two options,” he told me. “One was to divest Valmet and become more focused, and the second was to build more businesses into the company. The old Metso was too small to be a true holding company and too big for the businesses we had, so we decided to become more focused. “Although the capital market in mining is slow right now, the megatrends driving the business are still present. We want to make the most of the industries we have today.” I couldn’t leave without asking about Weir Group’s failed bids for Metso earlier this year; why was the deal rejected? “They approached us twice, once in April and then again in May,” said Kähkönen. “Twice the board came to the conclusion that it was better to continue as a standalone company; Weir was still significantly undervaluing Metso’s potential going forward. Our new strategy is generating excellent value for shareholders. “I think their decision sent a very clear message to the market: we have a good strategy and all the tools, people and technologies we need to truly believe that it will create more value. I’m very supportive of that.” CARLY LEONIDA, EDITOR carly.leonida@mining-magazine.com

Twitter: @MM_Ed_Carly

Next month Flotation Open-pit mining techniques & equipment Business-management software Bulk handling & stockpiling Industrial minerals

COVER

Wirtgen surface mining in Russia: selective limestone mining without drilling or blasting. A member of the Eurocement Group, the ZAO Kavkazcement mine is located near the Black Sea in Russia and is one of the largest cement producers in the northern Caucasus. In the selective mining of limestone, Wirtgen surface miners guarantee constantly high daily rates without drilling or blasting while increasing safety in the mine at the same time. Three 2500 SM units are currently operating in the mine. www.wirtgen.de/mining

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2

NEWS

In Brief Bridgestone hits Chile Bridgestone Industrial Products America has established a new company in Santiago, Chile, for the sale of industrial materials such as conveyor belts to copper mines across South America. Bridgestone Productos Industriales Latinoamerica (BIPL) will begin operations in October.

RMI launches pumps RMI Pressure Systems has launched a range of highpressure pump stations for powering roof-support systems. The new Streamline range has been developed for use in second-tier mines and has been created using a standard product offering. RMI stated that this approach has allowed it to increase the scale of production and reduce the manufacturing required without impairing any of the safety and reliability factors involved.

Latest Komatsu ADT Komatsu Australia has introduced the HM400-3M0 articulated dump truck (ADT). Powered by a Komatsu SAA6D140E-6 engine rated to produce an output of 350kW, the new vehicle can carry a 40t payload at speeds up to 55.9km/h. The HM400-3M0 replaces the HM400-2 and offers a higher payload capacity, better operating performance, lower fuel consumption and increased operator comfort than the predecessor model, the company stated.

Cat 824K offered Caterpillar has introduced the new Cat 824K wheel dozer. With a net power rating of 302kW and a maximum operating weight of 34t, the 824K has been made available with six blade configurations ranging in capacity from 5 to 16.2m3 to customise it for use in production dozing, stockpile dozing or clean-up work.

ABB kits out S11D in Brazil ABB has won a US$103 million contract from Vale to install electrical and automation systems at the S11D iron-ore project in the Carajás mountains of northern Brazil as part of a major capacity expansion to 90Mt/y. Rather than employ trucks, the mine will use conveyor belts to move rock and ore around the site. This is the first time such a solution will have been used on a large scale at an iron-ore mine. Vale estimates that if S11D were to be operated using conventional means, it would need a fleet of around 100 off-highway trucks that

Truckless material handling at Vale’s Carajás iron-ore mine consume 77% more diesel per year. The order follows a previous US$140 million contract won by ABB in September 2012 to complete the first phase of the S11D project, supplying and installing automation and electrical

equipment for the process plant that separates the ore from the spoil material. ABB’s first contract required the installation and commissioning of the primary transmission substation. In the next phase, it will extend the electrification system to the excavators, stackers, reclaimers and conveyor-belt system at the mine. ABB will supply a 230kV in-feed substation to connect the mine to the electricity grid as well as 42 secondary substations contained in e-houses. It will also supply the motors driving the mine’s conveyor belts.

FLSmidth wins biggest BMR order yet FLSmidth is to supply Blair multi-rope (BMR) winders for Glencore’s Mindola shaft at the Nkana mine and the Mufulira shaft at Mufulira mine, both in Zambia. This is the highest-value order that FLSmidth’s mine-shaft systems business has received for BMR winders to date. The company has installed more than 90% of the world’s BMR winders and has been actively involved in their development since the first installations in 1959. FLSmidth will supply identical equipment for both shafts, each of which will incorporate a double-drum BMR rock winder and a single-drum BMR man/ materials winder. The drums are almost identical for all four

GIL Automation achieves CSIA status GIL Automation has become the first company in Africa to achieve Control System Integrators Association (CSIA) certification. Based in Nigeria, GIL serves the mining, oil & gas and power industries. CSIA certified members are independent, professional service providers who offer the best solutions for automation projects. Certification requires companies to undergo an intense third-party audit and follow strict performance standards. Members must meet or exceed 79 criteria.

ABB Blair multi-rope winder winders, each measuring 5.7m in diameter with two 1.8m-wide rope compartments. This will also be the second customer where a Hooke’s joint application has been used in mine hoisting on the African continent, and the first for Zambia. The Hooke’s joint is a universal coupling used on double-drum BMR winders to link the two

drums mechanically without the use of gears. This allows the drums to be angled towards the conveyance centres to improve rope fleeting angles. FLSmidth said that the system offers significant capital cost savings over electrically coupled winders. The cost of a BMR installation is offset by the higher tonnages that can be hoisted using twin ropes per conveyance. FLSmidth will begin delivering the mines in the December quarter of 2015, with installation to start in 2016. The drums are being made by a South African company and the drum shafts by an international supplier. Voith is manufacturing the Hooke’s joints for this application.

Nominations open for MM awards Nominations are now open for the annual Mining Magazine Awards. These recognise outstanding new technologies, initiatives and equipment performance in the mining sector over the past year. If your company or one of your clients has achieved something exceptional during 2014 and you feel it should be recognised, For breaking news as happens, follow our editorial team on Twitter at @MM_Ed_Carly and @MM_AsstEdAilbhe it

nominate them online at www.miningmagazine.com or contact Ailbhe Goodbody at ailbhe.goodbody@miningmagazine.com. Please provide the company name and a 100-word description explaining why they deserve the award. Nominations will close on Friday, October 10. The shortlist for each award will then be announced, and final voting will open at the end of October. The winners will be detailed in a supplement accompanying the January/February 2015 issue of Mining Magazine.

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4

NEWS

RPM-Sinapse deal expands capabilities

The bigger picture The first Wirtgen 2200 SM 3.8 surface miner has been put to work at the Yihua Xinjiang Wucaiwan coal mine in China’s Xinjiang province. Contractor Xinjiang Jianyun Engineering Co has been extracting coal at the operation using surface-mining technology for nearly two years. Previously, the mine utilised conventional drill-and-blast methods. However, this often resulted in fires as the coal is highly flammable. In order to increase safety and boost production from 3,000t/d to 7,000t/d, the mine operator decided to switch to surface mining.

RungePincockMinarco (RPM) has entered into a strategic business partner agreement with IT systems integrator Sinapse. Under the agreement, Sinapse will work with RPM on software implementation projects across Australia, in particular with RPM’s enterpriselevel software solutions. RPM said Sinapse’s depth of experience as an SAP ERP services partner aligns with the company’s software-integration strategy, which has focused on SAP systems. RPM’s own enterprise capabilities have expanded rapidly since the initial launch of XERAS for Enterprise, its first enterprise solution, 18 months ago. Craig Halliday, director of software at RPM, said: “Our partnership with Sinapse will help

SAFEmine introduces FatigueMonitor SAFEmine, part of Hexagon Mining, has developed a multi-technology fatigue-detection system for monitoring driver alertness within the mining environment. SAFEmine said that in the open-pit mining environment approximately 65% of truck haulage accidents are directly related to driver fatigue or exhaustion. In response, it developed a solution that integrates data from fatigue-detection and collision-avoidance units to help minimise accidents involving mining vehicles. FatigueMonitor is designed to help operators maintain the attention required during mining operations, while providing mine management with driverfatigue profiles and traffic-related

data from the open pit. Based on scientific research by the University of Zürich, smart fatigue-assessment algorithms are used to estimate driver fatigue levels and to predict fatigue development based on operator history. FatigueMonitor assesses the current fatigue levels based on individual situations, e.g. speed of the vehicle, area in mine etc. The system back-end consists of a live web platform that provides dispatchers within the control room with real-time fatigue analysis associated with the entire fleet. In

A FatigueMonitor unit

Schneider opens new American HQ Schneider Electric has opened a new North American R&D centre in Andover, Massachusetts. The Boston One Campus will also serve as the company’s new North American headquarters and will house approximately 750

addition, reporting services provide supervisors with updates via email or text messages. When the mine management team is alerted that an operator is experiencing early stages of fatigue, they can manage and reassign operators to maximise safety and efficiency. Within the control room, a live web platform continuously analyses fatigue levels associated with individual drivers and the complete fleet. The black-box recording technology provides a reliable tool for analysing incidents. FatigueMonitor is operator-friendly and does not require drivers to wear additional equipment such as glasses or caps. FatigueMonitor is a simple upgrade to existing SAFEmine Collision Avoidance Systems.

employees across all of Schneider’s business segments. The Boston One Campus incorporates approximately US$8 million of Schneider Electric’s own products and solutions and is expected to achieve an

operating-cost reduction of about 30% in its first year. The new centre integrates engineering, sales, marketing and customer-support functions across multiple disciplines and is one of five global R&D centres owned by the company across the globe.

to strengthen our implementation capabilities, allow us to take on even bigger and more complex projects and deliver greater value to our clients.” Working closely with RPM’s team, Sinapse will leverage its knowledge of complex ERP environments to provide clients with tight integration with RPM’s suite of products. Halliday explained: “We have an established technical team that has deep domain experience. Combining this with Sinapse’s ERP integration expertise will help us to deliver significant benefits for our clients.” This agreement took effect on September 4, appointing Sinapse as RPM’s non-exclusive implementation partner in Australia. EXSA’s Quantex

Better blasting with Quantex Peruvian rock-fragmentation solution provider EXSA has launched a new technology called Quantex. This is claimed to improve the efficiency of blasting in open-pit mining and construction, and avoid the use of porous ammonium nitrate. EXSA stated that this could result in up to 20% savings in the total cost of rock fragmentation. Quantex was developed in Peru by EXSA’s R&D team and put through rigorous testing. It is already being used in Peruvian open-pit mines, and EXSA has plans to introduce it in other countries. EXSA added that the operational benefits of the technology include: • Increased water resistance; • Increased energy and therefore better rock fragmentation; • Environmental benefits through the elimination of nitrous gases and smaller carbon footprint; and • Fewer negative effects resulting from operational failures.

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6

speciAl reporT

The dump trucks were shipped to Israel in 2012, partly disassembled, and completed on site

driving productivity forward in israel Two years after delivering six EH3500ACII dump trucks to Rotem Amfert Negev’s phosphate mine in southern Israel, Hitachi returned to see how the machines are adapting to life in the Negev Desert

R

“This is the only mine in Israel and therefore our equipment is unique. In the past, we have had issues with other suppliers, who have gone by the wayside”

otem Amfert Negev (Rotem) was formed in 1991 through a merger of Negev Phosphates, which was established in 1952 to exploit the phosphate reserves in the Negev Desert, and the Rotem Amfert Group, which was originally established as Rotem Fertilizers in 1977 to process phosphate into phosphoric acid and fertilisers. The company became part of ICL Fertilizers after a further merger in 2001 and is now positioned as an integrated, multinational phosphate group. Its wide range of products are based on phosphate rock as a raw material and lead to downstream derivatives such as phosphoric acids, fertilisers, specialist chemicals and phosphate salts. The current lifespan of the company’s 72km2 mine is seven years and the management team is working towards a long-term plan via new mining areas and methods. Guy Eitan joined the company in 2007 and is now the mining-equipment maintenance manager, responsible for all aspects of Rotem’s mining equipment, ensuring high levels of availability and safety at the operation, and what he described as an “unofficial problem-solving role”. The acquisition of the new trucks in 2012, which replaced a fleet of old Euclid models, including three that had clocked up more than 100,000 working hours over 26 years, soon became one of his ongoing projects. “I asked for approval to change the old trucks,” he explained, “and it seemed that there might be a good chance of this happening in 2009. So, we started the long process required for this

type of investment and looked at a list of possible suppliers.” A shortlist of five leading rigid dump-truck manufacturers was reduced to two, due to the size of the product required and the need for the machines to be electrical. The contents of the final two proposals were similar, so there was a long and detailed process of negotiations, before Hitachi was selected as the preferred supplier.

The besT soluTion “We didn’t only evaluate the best product,” said Eitan, “because it was also important for us to assess the whole package. This included a number of different parameters, such as maintenance, parts and servicing, as well as operator comfort and the capital cost.” Malcolm Edwards, manager of mining and quarrying at Hitachi Construction Machinery Europe (HCME), was also heavily involved in the process. “Rotem chose Hitachi because it could offer the lowest owning and operating cost, and its own electronics for the truck’s drive system,” he said. “They also saw the successful operation of the EH3500ACII trucks at the Talvivaara nickel mine in Finland in temperatures as low as -32°C and as high as 35°C.” “This is the only mine in Israel,” added Eitan, “and therefore our equipment is unique. In the past, we have had issues with other suppliers, who have gone by the wayside along with their local distributors. So, it’s great to have an active local dealer such as CMD to help us. The direct communication and access

to HCME has also been a huge help.” Once the deal – the largest sale of mobile plant equipment in the country’s history – was finalised, Eitan’s attention shifted to checking that each element of the package was on track for delivery. This incorporated everything from the training and logistics to the supply of the tyres, rims and bodies. Each truck was to be shipped 90% built – without the body, wheels, final drives and other components – and then on March 11, 2011 a devastating earthquake and tsunami hit Japan… With a force majeure in place, a delay of some months was expected and Hitachi and Rotem scheduled a new delivery date. When the trucks were ready, Eitan took Meir Shemtov, head of the heavy construction equipment garage at Rotem, and another colleague to the Hitachinaka-Rinko Works factory in Japan for 12 days’ training, accompanied by CMD’s service manager and a technician allocated to the project. “The training course was a very interesting experience,” said Eitan. “It highlighted that the technology within the EH3500ACII is a leap forward from the seventies’ design of the Euclid. That was when I realised that we need to think differently and change the mentality of our people.” Shemtov, who has worked at the mine for 31 years, added: “The biggest benefit from our training in Japan was that it helped us to assemble the trucks when they arrived at the mine. We were also able to pass on our knowledge to the other members of our team with the help of CMD and Hitachi. After the success of the early training sessions, we still have a monthly refresher course for our technicians and operators.”

A giAnT leAp forwArd The trucks were shipped to the port of Eilat in southern Israel, then made the journey north to the mine by road. Following their arrival at the site in April 2012, mine personnel took six weeks to complete assembly with the help of CMD and Hitachi experts. The operators then undertook a one-week training course, not only for driving the machines, but also basic maintenance tips; they visually inspect the truck at the start of each shift and are able to check a special reference book that has been prepared by Rotem. Finally, from mid-May to the start of June 2012, the machines began working on 20-hour shifts (or a scheduled 6,400h/y). They are now being used to remove overburden and haul the phosphate to storage areas, the crusher

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special report

and the processing plant at the mine. “As the main co-ordinator of the project, I made a huge effort for it to succeed – from the dismantling of the trucks in Japan to the anticipation of their arrival at the mine,” added Eitan. “Every step of the process brought more excitement, including the first test run, which was carried out in rigorous detail.”

Maintaining the Machines The Hitachi Support Chain after-sales programme kicked in at the same time as the EH3500ACIIs started working in temperatures approaching 50ºC. The trucks undergo a maintenance check every 250 working hours (or every 12 days), which includes changing the oil and filters, measuring the suspension, checking the electrics and anything that has arisen from the service bulletin, as well as an overall visual inspection. In addition, the Rotem team uses preventative maintenance, oil sampling, thermography and other techniques to provide the best possible service to the machines. Hitachi also recommended the parts that the mine should keep in stock for the scheduled maintenance and servicing work. The team includes 29 technicians,

SR_Hitachi-Israel_MM1410.indd 9

including three electricians, two lubricant specialists and four welders. They are available on one 12-hour shift (7am-7pm) with two personnel on call to provide cover through the night. One of CMD’s technicians was also based at Rotem for the first two years of service. “As the mine’s technical department, we also like to come up with solutions for any issues that might arise,” said Eitan. “We are proud that we have made some small improvements to the trucks and our tools. For example, we have fitted a tyre-monitoring system, which enables us to check the pressure and temperature. “There are many challenges encountered at the mine: from the working environment and understanding the machines, to potential errors made by operators or technicians. We manage

all of these issues to optimise availability, combined with safety at the lowest possible cost – any decision can save or lose money, depending on the outcome.” Shemtov added: “Our job has been made easier with the acquisition of the EH3500ACIIs; for example, there is less maintenance with the switch from DC to AC drive. They have also been constructed with high-quality materials, so there is less repair work to be carried out. “If there is an issue with a machine, then the operator can see a code on the monitor and this will help him to decide on an appropriate course of action. The troubleshooting is easy and means that we can quickly find a fault and repair it. The level of communication between the truck and computer system is also impressive, with all of the available data, such as fault codes, fuel consumption and load time – it’s a smart truck. “We also find out some invaluable management information, for example the fuel consumption is less than that of the old trucks. We can also see if the operators are slowing the trucks down in the correct way or if they are being loaded correctly. It’s a whole new way of working.”

9

The six EH3500ACII trucks are working a scheduled 6,400h/y at the mine

“Our job has been made easier with the acquisition of the EH3500ACIIs”

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10

SPECIAL REPORT

Mobile mining Christian Funk discusses bringing the benefits of mobile computing to the mining industry

Above: Christian Funk Right: The VERSO 12, one of the latest in a range of touchscreen rugged tablets introduced by JLT Mobile Computers

W

hen the word ‘mobile’ is mentioned it most likely invokes an image of a smart phone and, for some, the cellular network infrastructure that enables it. Indeed, in many parts of the world the word ‘cellular’ or just ‘cell’ is interchangeable or even preferable to the word ‘mobile’ when talking about handsets. However, the benefits of mobile technology are not limited to the consumer sector. The use of mobile technology is quite different in concept from cellular technology: mobile literally means free to move, and this is a quality that is becoming increasingly important in many sectors, including mining. The challenge here is that the mining environment is not always conducive to the needs of relatively sensitive electronic equipment such as a smart phone. Moreover, creating an infrastructure that supports mobile technology in a mine holds many challenges, but they are challenges that are being met, for very good reasons.

The next step in modernising the mining industry is, therefore, putting mobile ENABLING CHANGE is an industry in transition and computers Mining technology is increasingly being into every employed in order to meet efficiency vehicle in a goals. Historically, the mining industry has enjoyed high margins. However, due mine, to the increasing challenges in finding allowing and extracting natural resources, many are now turning to technology to them to miners help improve their overall efficiency. acquire and relay data from anywhere

Primarily, this can be achieved through the acquisition and analysis of data. This is a proven formula. Other industries already employ advanced data-acquisition techniques coupled with data analytics to drive up efficiency in manufacturing, transport and distribution. The first tentative step towards a more data-centric environment was taken with the move from VHF to digital radios, which supported a higher volume of data transmission. This enabled greater integration between disparate systems, such as traffic control and ventilation. However, the environment puts specific demands on the infrastructure. Line of sight wireless communication in a deep mine can be impeded by the surroundings (typically ore-laden rock), so while WLAN technology is the preferred solution, its implementation can be much more challenging than in a modern factory, for example. An important aspect of that environment is its propensity to change. Mining involves the removal of material, so the landscape is forever changing. This demands not only a robust infrastructure, but one that can be rapidly adjusted. In this respect, it is much more ‘mobile’ than a typical cellular network. The equipment used in mining can also represent obstacles to signals. Multi-path transmission can cause an overall degradation in signal quality in a wireless network – something that will be much more prevalent in an environment where large radio frequency-reflective obstacles are constantly moving. For these reasons, the industry is still evaluating technology and looking for an optimal solution, but some aspects are already well established, such as the use of robust mobile computers.

FINDING A SOLUTION A JLT computer in the cab of a mining vehicle in one of Boliden’s Swedish gold mines

Ruggedised laptops are an option, but they are not the optimal solution. There is already a shift away from distributed data acquisition with local storage,

towards a more centralised approach. Again, this is an evolution that has been apparent in other industries. The next step in modernising the mining industry is, therefore, putting mobile computers into every vehicle in a mine, allowing them to acquire and relay data from anywhere. This clearly has implications on the design of the mobile computer – it needs to be able to withstand the harshest environments, while still being truly mobile – but the benefits are clear. Enabling greater integration between the assets of a mine will undoubtedly bring efficiency gains. The ability to connect more aspects of an operation will deliver immediate benefits in every aspect of mining. Today, distributed systems rely on a back office for data analysis, but tomorrow will bring greater intelligence to the system, allowing increased autonomy and automation. There are already examples of mines today that are almost entirely automated, and this trend will naturally extend to larger mines in less remote areas. While this technological evolution is largely confined to ore mines today, there is every reason to expect it will be adopted in other areas of mining in the future. Along with robustness and flexibility, closely coupled with the latest technology – features that are common to all industrial computing applications – a critical aspect of the infrastructure needed to support this in the mining industry will be mobility, for both the equipment and the infrastructure.

Christian Funk is sales and marketing director at JLT Mobile Computers (jltmobile.com)

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12

special report

engineering excellence Following on from MM’s specialty steel focus in July, Carly Leonida visited Weir Minerals’ European HQ to see first-hand what makes a world-class foundry tick Pump components being produced in the foundry at Weir Minerals’ Todmorden plant

“I want to make sure that when the market returns, we are ready for it. I don’t see any negatives, just a different set of challenges”

T

he past 12 months have been exceptionally busy for Weir Minerals’ Todmorden facility in West Yorkshire, UK. Despite the depressed demand for mining equipment, the company has been focusing its efforts inwards, streamlining production processes at its European headquarters, and investing in skilling its employees. MM visited to tour the facility and interview Tony Locke, managing director of Weir Minerals’ European business. Our visit came on July 18, the day after Malaysia Airlines flight MH17 was brought down by rebels in eastern Ukraine, further fuelling political unrest that has plagued the region since the start of the year. Naturally, the issue was top of the agenda for Locke; Weir Minerals Europe has a sales office in Dnepropetrovsk (near Donetsk), and the area holds significant potential for mining sales growth. “Our Ukrainian office has gone from strength to strength in the last few years. We have developed excellent relationships with many key accounts, improving their ownership costs for process equipment, and we have big plans to build on this success,” explained Locke. “But the safety of our employees and their families is our top priority, so we are monitoring the situation very closely.” Despite having more pressing matters, Locke found time to chat with MM, and was keen to tell us about some of the projects that he and his team have been driving; but first, a little context… The Weir Group employs 14,000 people globally across its three divisions: Oil & Gas, Power Industrial, and Minerals. The company has manufacturing bases on every continent and 143 years of experience under its belt. Weir Minerals’ European business, which also covers North Africa, is centred at Todmorden; a community at the heart of Britain’s industrial history. The site sits in the centre of town and covers approximately 9.3ha (23 acres), employing around 400 of the 778 people working across the European business. The Todmorden facility is a key centre of

metallurgy research for the group, developing the latest alloys used across the global business to meet the demands of the market. Its metallurgy professionals work closely with a second team of material scientists in Sydney, Australia. Other core competencies are handled at sister facilities; for example, rubber products are developed globally, with a centre of excellence in Malaysia, and European production handled at Weir’s base in Yateley, Hampshire. The Minerals division produces a range of equipment for the mining sector including milling, comminution including HPGR, slurry transportation, and mine dewatering solutions, under brands such as GEHO, LINATEX, ENDURON, WARMAN, CAVEX and GEMEX. Key mining markets for the European business include Scandinavia, Spain, Portugal, Russia, Kazakhstan and Turkey.

UniqUe set-Up The Todmorden facility is unusual in that it covers the entire alloy-production process: handling raw materials, melting and casting its own metals, through to fettling (removal of metal burrs), machining, heat treating and assembly of final products ready for shipping to customers across 93 countries worldwide. The business has invested heavily in equipping the foundry with leading-edge casting technology, and the site now has several different moulding sections. For high-volume light-medium castings such as impellers, or one-off prototypes, Weir uses the Replicast process, which is a variation on lost-wax casting. The company has been doing this for over 30 years but only started producing its own Replicast patterns 12 years ago. In Replicast, exact polystyrene replicas (hence the name) of the final parts are produced using steam in aluminium moulds. The polystyrene parts are painted in resin to prevent sand from sticking to the molten metal, and placed in boxes filled with sand. Vacuum pumps are used to suck air from the box, and as the hot metal is poured onto the

polystyrene and into the mould, it burns away the polystyrene, leaving a very accurate solid metal casting in its place. The tooling to produce each type of polystyrene model costs £4,000 (US$6,600) to produce, hence its reservation for high-volume items, but the method produces very ‘clean’ parts that require little fettling before machining. Heavy castings, such as pump casings or volutes in the medium to large size range, and lower-volume light-medium castings (e.g. parts for pumps in the A6-8 range), which must be produced in two halves and bolted together at assembly, are produced using traditional sand-cast methods with wooden patterns, which are handmade on site. The company made a significant investment of £5million (US$8.5million) in 2012 to add a new semi-automated ‘fast loop’ and increase the production of light-medium castings that were in high demand. The company did consider fully automating the process, but the cost (nearly double) was prohibitive. The introduction of the fast loop has allowed a significant increase in capacity – three castings can now be produced per hour before being allowed to cool. The facility was completed in April 2013 and has already proven its worth. As demand increased on the foundry, the management team invested a significant amount of time to fully understand the conveying velocity of product throughout the plant, with a desire to speed up the flow of castings, increasing the output while reducing the inventory buffer stock levels with improved replenishment times. To achieve the velocity gains sought, Weir’s lean specialist worked with the technical teams to collect data from the shop floor, so that the flow of products through the system could be tracked and any non-value-added activities identified and removed. One of the main areas identified by this was the lengthy cooling processes, and an improved cooling technique was developed to speed the process up. Weir

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14

special report

Casting under way at the Weir Minerals facility

developed this 5-6 years ago and it has succeeded in halving the cooling times of most parts without compromising the strength or structure of the steel. However, the sheer size of the largest parts means they cannot be included in the new system. For example, the volute for Weir’s largest Warman pump weighs 21t and takes 21 days to cool, which limits production to one per month. The casting process for each component is also carefully modelled using digital casting simulation package Magmasoft – the industry standard. This allows specialists to understand solidification and cooling-stress patterns in order to inform the casting design. The method allows complex geometries to be tested for soundness and integrity before casting, and enables a shorter development cycle. The software has a bespoke database of Weir’s proprietary alloys, which are incorporated into the simulation so that the results exactly replicate the materials and conditions used for manufacture.

creating opportunities

The volute for Weir’s largest Warman pump weighs 21t and takes 21 days to cool

The Todmorden facility has seen a drop in enquiries over the past 12 months in line with market conditions. However, Locke has been using the opportunity to continue to develop lean manufacturing methods at the site, such as 5S. “When you’re running at 150mph to keep up with customer orders, you don’t always get the time to look at your processes and how you can optimise them. Our enquiry levels are not where they have been previously but that will come back, and when the market returns, we will be ready,” said Locke. “In 2006 we were struggling to produce more than 180t/w of steel; now we can produce 360t/w,” he explains. “We use shop-floor data collection to measure how long it takes from production to despatch for each product. We then look at areas where the product is sitting waiting and aim to reduce those times. If we can increase the velocity of products, then we can carry less buffer stock because it can be replaced quicker, and if we’re not producing buffer stock, then we can work on customer orders.” Locke continued: “From my point of view, if we don’t work to improve our processes and get smarter, then we will go out of business. If we can get the waste out of the business and become more competitive, we can bring more work in and that benefits everybody.” The Todmorden site is also using some of its spare capacity to manufacture parts for its sister companies, and Locke credits good integration between Weir’s divisions

as the enabling factor in this equation. The Weir Group has other foundries in Australia, South Africa, South America and has recently invested in a new facility in Malaysia, but can flex its capacity globally to meet market demands.

adding value for clients Aftermarket services are currently a big focus for Weir Minerals Europe, and the business has invested heavily to offer commissioning, on-site services, product rebuilds and service-exchange capabilities. “In 2007, we had three mobile service engineers; now we have 137 across Europe. The extended reach means we can get much closer to the customer, reducing response times and ensuring that our engineers have key replacement parts at hand whenever they’re needed,” said Locke. Weir Minerals Europe has 24 sites (service centres, offices and manufacturing facilities), and will open a new service facility in Italy next year. Weir’s facility in Casablanca, Morocco, has just commissioned an application for OCP, where phosphate is pumped 185km from the mine to a port, and its German office has taken an order for a tailings expansion project with Norilsk Nickel. “Our service-centre growth has been very aggressive,” commented Locke, “and although I do have more locations in mind, the next nine months will be about consolidating, checking that everything is working as it should and ensuring that our inventory matches customers’ needs. That said, if the relationship’s right with the customer, I have no problem opening a local service centre to support them.” Customer relations are very important to Locke. He gave an example from Spain where Weir has a large mining account. “The project had been incorrectly designed by another business and the spares generation equated to nearly £750,000 a year,” he explained. “We recognised that this wasn’t sustainable, so rather than just take their business, we sent in our applications engineers, redesigned the circuit and went from pumps lasting 32 days to over a year. The aftermarket stream dropped, but our relationship with that customer has moved on significantly and we’re continuing to work with them.”

Locke cautions that in the current market, it is easy for new projects to become driven purely on price. “My concern is that the customer doesn’t always get the benefit of total cost of ownership when procurement is purely based on capital costs,” he said. “A short-term decision can have a long-term impact, and there have been a number of occasions when we’ve had to reengineer a solution to optimise it.” For Weir, having the opportunity to work with a customer to optimise its plant design is crucial. “It’s all about preventative rather than reactive maintenance. It’s about getting the mines to think more in that vein, and we are starting to see this come through at more mature mines and in certain geographies. That’s where we can start to add real value,” Locke added.

a multinational business In terms of the number of countries served, Weir Minerals’ European business is probably one of its most complex, so why choose the UK (a country with relatively little mining) for your base? According to Locke, it all comes down to legacy and quality. “This business was built around a foundry that started making parts for Simon Warman in the 1960s. We’ve grown organically, built on the fact that we’ve had manufacturing capability here and have successfully managed to support the European business,” he said. “We focus a lot on the competence of manufacturing and that’s why we’re keen to keep the business here, particularly as our use of lean manufacturing continues to develop.” Due to market conditions, the Todmorden foundry had to adjust its workforce late in the March quarter. “We’ve tried to make sure the core of the business is kept,” said Locke. “I wish the market were more buoyant, but it hasn’t changed some of our long-term projects and investments. We’re very keen on apprentices and bringing the right people in at the right time, and we’re continuing our programme this year. We’re also keen to take graduate apprentices through to degree level. We’ve got some great young people coming through and we will continue to invest, not just in engineering but also in IT, supply-chain logistics and all other operations.” As we prepared to leave, Locke summed up our conversation rather well: “The market is fickle, but while we’re in this position, we need to continue to look at areas of improvement. I’m as busy as I’ve ever been, and I want to make sure that when the market returns, we are ready for it. I don’t see any negatives, just a different set of challenges.”

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16

futurecasting

the future of mining In the first of a six-part series of articles, George Hemingway and Jeff Loehr of the Stratalis Group outline Futurecasting; a tool to drive change within the mining industry

D

Top: George Hemingway Above: Jeff Loehr

Below: one artist’s vision of the future of underground nickel mining

onkeys are a good way to transport material in an underground mine. They are reliable, obedient and can stay underground for up to three months at a time without complaint. Even so, no reputable mining company today would use them as a primary means of conveyance. Donkey usage exists only on the fringes, along with tin hard hats and canaries. In hindsight, the move to machines was an obvious one. Machines are more reliable, stronger and can stay underground forever. At the time, however, the choice to shift away from donkeys was risky and uncharted. Today’s technology has enabled concepts such as remote mining, automated operations, predictive management and modular machine configurations. Any one of these concepts represents a new approach that could revolutionise mining operations. Combined, they could revolutionise the industry. In the future, what is viewed as revolutionary today will seem obvious and necessary. With hindsight, our labourintensive processes will seem as archaic to others as donkeys seem to us. The challenge today is to stop operating in the same ways and instead consider what the future holds and how to generate a competitive advantage from it. Futurecasting is a powerful tool that we use with global mining companies to think about the future and, in doing so, inform decisions today. By exploring market drivers, pain points, trends and uncertainties in the present and blending

them with aspirations, it is possible to imagine potential development pathways and possible futures. We can then look backwards from those points to build a roadmap that answers the question: how do we get there? Futurecasting is not prediction. We recognise that we cannot predict the future and that visions of the future are going to be flawed. We know that we cannot account for that which we have never seen, heard of or imagined. Instead, Futurecasting provides a context to understand changes happening now through an inductive, creative process. It takes participants on a journey where the process of imagining the future is as important as the visions created. In the end, we are less concerned about whether our visions are precisely right or wrong and more interested in what they suggest about our world and businesses. Simplified, the process starts with identifying trends in three broad areas: society, economy and technology. Economic challenges, such the development of the global economy and the resultant impact on commodity demand, sovereign drivers, environmental sensitivities and energy uncertainty will have a significant impact on the mining industry. Technology developments, such as advances in nanotechnology and artificial intelligence, have the potential to change operations. Societal shifts, such as the ageing workforce and expectations around safety and collaboration, could redefine organisational models. We then take these trends and observations and put them together to paint multiple future visions, which we then use to explore the implications and strategic options for the current world. A well-known example of Futurecasting that drove investment strategy is AT&T’s ‘You Will’ advertising campaign from 1993-94. AT&T imagined a future that included video payphones, automated toll roads and global positioning systems. In all cases, the manifestation of the technology was different from the Futurecast, but the larger themes were right. Assuming that AT&T used this thinking as the basis for

its investment strategy, it would have positioned the company very well for the world today. Futurecasting also has the potential to motivate changes in business models. One company we worked with discovered that the opportunity in its industry was not in the company’s existing products (in this case, commodity food), but in the customisation and delivery of new and innovative products direct to consumers. Understanding this, it identified a new operating model and is currently shifting from commodity food production to specialised, higher-value services. Through Futurecasting, companies can also influence technology development. In mining, at one time, the idea of a self-driving truck measuring larger than a house seemed absurd. Examining its visions of the future, one company recognised that automation was coming and took the opportunity to invest heavily in making automated haul trucks a reality. Today, haul trucks drive themselves and the company in question is at the forefront of realising the benefits of integrating these trucks into its operations. Whether or not automated haul trucks became a reality because of a mining company’s investment, or whether AT&T’s investment in commercial GPS gave it an edge, we may never know. What is certain is that an exploration of the future provided a framework for strategy and investment that has allowed these companies to create a competitive advantage and, ultimately, win in their respective industries. Over the next few months, we will detail some of our Futurecasts and explore some of the trends and technologies that will impact the future of mining. We will also present possible implications for executives, operators and suppliers across the industry and some food for thought around how to shift your business model. We will not predict the future, but we will provide a framework to explore it. There is, however, one prediction that we are willing to make; there will be no donkeys in our visions of the future. Unless, of course, they are automated.

The Stratalis Group is a full-service strategy and innovation consultancy focused on helping leading companies in the resource industry to discover, develop and deliver new pathways to growth. See: www.stratalisgroup.com

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18

Mine of the Month

Made in england

“We will mine in two months Carly Leonida looks at progress at Wolf Minerals’ Drakelands what has tungsten project, the first new mine in the UK for nearly 50 years been mined previously; early 1970s to reopen the mine failed, t has been a solid start to the year for until US-based AMAX became involved in Australian miner Wolf Minerals. Folit’s a the late 1970s and an exploratory drilling lowing the grant of an environmental completely permit for its Drakelands mine site near programme got under way in 1977. In 1986, planning permission was granted different Plymouth in Devon, UK, at the end of 2013, the company successfully raised the by Devon County Council; however, due scale of capital needed in March to break ground to a fall in the tungsten price, AMAX operation” at the site, and the pace of work has now decided to discontinue the project and it

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In the foreground, Wolf has demolished the old mine plant which was constructed around the time of the First World War. In the distance, foundations are laid for the new processing facility

picked up significantly. On a visit to Drakelands, formerly known as Hemerdon, on July 4, managing director Russell Clark and operations manager Jeff Harrison talked MM through the work that has already taken place, as well as plans for the next 12 months.

historY The discovery of tungsten near Hemerdon dates back to 1867 and the site is now recognised by the British Geological Survey as the fourth-largest tungsten resource in the world. The first significant workings took place around the time of the First and Second World Wars, although by today’s standards the operations were relatively small. “We will mine in two months what has been mined previously; it’s a completely different scale of operation,” explained Clark. Operations ceased in 1944 due to the reinstatement of tungsten shipments from overseas. Attempts during the 1960s and

reverted to the original landowners. Wolf Minerals picked up the project in 2007, and in 2008 appointed SRK Consulting (Australasia) to provide a mineral resource based on existing AMAX drilling data. Scoping-level studies followed and the definitive feasibility study (DFS) was released in May 2011, at which point the planning permission that covers mining at the site until 2021 was updated and Wolf began to seek funding to develop the mine. Clark came on board in October 2013. “Humphrey Hale [Wolf’s previous MD] is an exploration geologist. He realised the company was at the point where it needed someone with more operational and development experience to take the project forward. What I found when I went out with analysts and brokers was that no one appeared to believe the story – a mine in England, in a pristine part of the country – they said you will never get the permit, and you’ve got to buy 15

residential properties as well,” he said. But that is just what Wolf did. The company received the environmental permit, the first of its kind in the EU, in December 2013, and bought the last property required by the planning permission shortly after. “Gaining the permit was quite a challenge because this is the first new mine in the UK in 45 years; no one from our side or the agency had worked through one of these permits before,” Clark said. “It came through in December and we finalised the 40-year lease with our three mineral and landowners [Hemerdon, Newnham and Olver Estates], which jointly form the Hemerdon Mine Association (HMA). Along with raising the equity needed, those were the two biggest hurdles.”

ConstruCtion The Drakelands DFS was based on a two-stage open pit with an initial 10-year life, and a 3Mt/y concentrator with associated infrastructure. The first major project was completed in 2012 when a 600m link road was built and opened between Lee Moor Road and West Park Hill in Plympton. Work to construct the mine, processing plant and other infrastructure started in March this year. The site has been cleared of scrub and the old concrete processing plant demolished. The 400m x 200m site for the new concentrator has been levelled and tailings ponds created. Pouring of the concrete foundations and steel work erection is under way, with the

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Mine of the Month

aim of having the buildings weather-tight by the end of October. “The idea is to take advantage of the summer weather, the rest of the work is inside,” said Clark. “We plan to wet-commission the plant in April-May next year, and be in production by the start of the third quarter, with first delivery of concentrate in September.” The project is currently on schedule and Wolf has a fixed-price contract (£75 million) in place for the concentrator, so the chance of costs overrunning from this aspect is limited. The bulk of the earthworks is now largely complete, and those costs are known and within budget. “We have five months for commissioning once we take delivery of the plant, and then a further six months to take the concentrator from 50% throughput to 100%; there’s a lot of comfort factors in there,” Clark added. Aussie engineering expert GR Engineering Services (GRES) won the tender to build the plant and has what Harrison described as “a small experienced team” on site, masterminding several British subcontractors. Clark noted: “I get asked a lot why we didn’t select a British engineering firm. The truth is, no one here has built a mine in nearly 50 years. “The knowledge and experience that GRES brings to the project, along with experts from the mine’s previous owner, who still consult for us, and local expertise within our management team help to provide our investors with reassur-

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ance that the project really will work.” Harrison, who worked for nearby chinaclay mine operator Imerys prior to joining Wolf, noted that the setting of the mine and ready access to power and water utilities have also contributed to the economic nature of the project. “If we were in Australia, we would have had to build an air strip, our own power station and a camp before we could even start construction,” he said. The mine will be an 800m-long x 450m-wide open pit and a 5m-high bund has been constructed around the excavation to shield residents from noise. There is still significant geotechnical work that needs to take place to determine the optimal angle of the pit walls, and the first of six holes was being drilled by Meridian Drilling during MM’s visit to provide data for consulting firm SLR’s engineers. Until this information has been calculated, a conservative slope of 40º will be adhered to, but by steepening the pit walls there is the potential to add another 2-3 operating years to the LOM.

operAtinG AnD proCessinG Wolf has a six-year contract (first year set-up, five years’ production) with British contractor Blackwells, which began to operate the mine in January , and the company will provide a new fleet of Caterpillar mobile equipment, including 16-17 Cat 775 haul trucks each with 65t capacity, presumably sourced from local dealer Finning. The equipment will be divided into two

fleets initially: one to mine the ore and one to remove the waste, with the option to introduce a third fleet in year three for further waste movement. At its peak the mine will move 10Mt/y of material; of which 3Mt/y will be sent to the plant to produce 5,000t/y of 65% tungsten concentrate (which will equate to 3,500t/y after smelting) and 1,000t/y of tin concentrate. All processing equipment for the plant has been ordered, most of which is off the shelf, from multiple suppliers including Sandvik, MDL and Holman. “The process itself is not particularly challenging, it uses gravity as wolframite [the primary ore mineral, tin is also present as cassiterite] is very heavy and easy to separate with proven technology such as dense-media separation (DMS), spirals and shaking tables,” explained Clark. “Primary, secondary and tertiary crushing plus screening will take the feed down to less than 9mm, which is quite coarse in mineral-processing terms, and the waste will be floated off.” The production fleet is expected to extract around 800t/h of ore, which will be fed to the run of mine (ROM) stockpile. This will be used to feed two Sandvik hybrid rotary crushers, each with a capacity of 500t/h, and from there ore is conveyed to a rotary scrubber trommel. Oversize from the trommel will be sent to two tertiary cone crushers working in closed circuit with the product screen, while undersize will gravitate to the scrubber screen fitted with a double deck of

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“I get asked a lot why we didn’t select a British engineering firm. The truth is, no one here has built a mine in nearly 50 years”

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Mine of the Month

British contractor Blackwells has a six year contract to set up and operate the mine

The site for the new primary crusher with a vehicle for scale

“We will understand the orebody and the extent of mineralisation a lot better in 18 months”

The mineralisation at Drakelands is hosted in quartz veins. Tungsten is present as wolframite, tin as cassiterite

9mm and 4mm aperture media. Plus9mm material will be combined with scrubber trommel oversize and sent to the tertiary crushers; product below 9mm plus the 4mm material will be directed to the 1,500t-capacity DMS feed bin. Crushed ore will be drawn from the DMS feed bin by two vibratory feeders, each feeding a primary DMS circuit at a rate of 150t/h. Each primary DMS circuit comprises a bank of three cyclones operating at a separating density of 2.7kg/L using ferrosilicon as the medium. Primary DMS floats will be rejected to the DMS floats bin and from there trucked to the mine waste facility (MWF). The primary DMS ‘sinks’ that will contain the bulk of the tungsten and tin will be sent to the secondary DMS circuit. The secondary DMS will operate at a density of 3.3kg/L. Secondary floats will be sent to the primary regrind ball mill, operating in closed circuit with a double-deck screen fitted with 1.7mm and 0.5mm screen decks. Plus-1.7 mm material will be sent back to the primary regrind mill and the minus-1.7mm and 0.5mm ore sent to the scavenger DMS circuit. Scavenger DMS sinks will join the secondary DMS sink product going to the concentrate regrind mill. Minus-0.5mm fines in the primary regrind mill screen undersize will then be pumped to the fines storage tank. Natural minus-0.5mm fines from the washing and screening circuit, plus fines from the primary mill, will be de-slimed in two stages using 500mm and 250mm cyclones. Deslime cyclone underflow will be pumped to three banks, each having 11 triple-start rougher spiral concentrators, and these will feed concentrate to the middling and cleaner spirals. Concentrates will then be pumped to the rougher shaking table and tailings sent back to the spirals feed. Rougher table concentrate will be screened at 0.15mm; both coarse and fine concentrates are further upgraded on two stages of shaking tables and the combined concentrate pumped to the flotation conditioner. The secondary and scavenger DMS sinks will be reduced in size in the concentrate regrind ball mill, in closed circuit with a 0.45mm-aperture concentrate sizing screen. Screen oversize will return to the ball-mill feed and undersize pumped to the flotation conditioner. The conditioner will receive concentrate from both the fines gravity circuit and the concentrate regrind mill. Sulphide minerals including arsenopyrite

will be removed by froth flotation, and non-floating minerals containing tungsten as pre-concentrate will be sent to a belt filter. Filter cake containing roughly 10% moisture will go to a concentrate dryer and from there to the reduction kiln. The top 30m of the orebody at Drakelands is fairly well weathered and the plant has been designed with a high clay content feed material in mind. “The guys we have working for us have come from the china clay industry, so they have plenty of experience mitigating problems with clay,” explained Harrison. “It’s about making sure chute angles are right, and that you have plenty of water to wash stuff through. The crusher that was going to be put in place in the 1980s was a jaw crusher, which is no good as clay tends to pack, whereas we now have a sizer that will feed clay through. It’s been given a lot of thought.” In Cornwall mine operator Imerys used a similar trommel set-up with dry feed at its Melbur site. “Because we’re not competitors, Imerys very kindly let us bring some of our managers and GRES people down to the site,” said Harrison. “There’s always the potential for problems but most of us are very experienced with these types of plants. At Drakelands we will mine softer clay-rich ore for the first couple of years, then move into harder granite.” “There’s a reason why we have a ramp-up period included too,” pointed out Clark. “So we can learn how to deal with the material and tweak the process if necessary.”

future opportunities While Clark’s initial priority is to get the mine running, there seem to be multiple opportunities to increase recovery and extend the LOM. For example, the

orebody is thought to extend at depth and to the south, although further investigation is yet to take place. “We will understand the orebody and the extent of mineralisation a lot better in 18 months when we have more people onsite and can use some of the information we’re generating to expand our knowledge,” said Harrison. Most drilling has been done to 200m (the current planned depth of excavation). However, two holes were drilled to 400m and proved that the mineralisation is still present. “As part of our current drilling campaign we may put another 3-4 holes down to that depth,” said Clark. When asked whether Wolf might consider taking Drakelands underground in the future, Clark replied: “The orebody may be suitable for block caving, bearing in mind that the grades here are good but not stellar. That has the potential to add another 10-15 years’ LOM upfront, but as Jeff said, once we have more experience with the host rock and the orebody we will be in a better position to determine the feasibility.” The mine will initially operate on a 24-hour basis for 5.5 days per week, closing at 6pm on Saturday and reopening at 6am on Monday. This is in accordance with the planning permission that was granted in 1986 under previous ownership, and which both Harrison and Clark acknowledge is somewhat outdated. “That’s another opportunity for us, to see if we can get permission increased to seven days a week. It would allow us to increase output by about 15% without any additional CAPEX,” explained Harrison. Once production gets under way, Wolf expects Drakelands to add around 3.5% to global tungsten output (currently 100,000t/y). The company has two offtakers in place for 80% of the product: one in Austria, Wolfram Bergbau und Hütten, which specialises in tungsten carbide cutting tools, and US-based Global Tungsten and Powders. Clark and Harrison’s enthusiasm for the project is certainly infectious, and it’s hard not to get excited at the prospect of mining returning to Britain. The southwest in particular has a rich mining heritage and, with companies like Wolf and the privately owned Treliver Minerals actively investigating the mineral wealth of Devon and Cornwall, as well as significant movement in Yorkshire and Scotland, it looks like there could be something of a renaissance on the cards for British mining.

Those interested in following Wolf’s progress at Drakelands can watch live streaming of construction online at http://www.wolfminerals.com.au/ hemerdon-tungsten-and-tin-project/live-stream

October 2014 MoM_MM1410.indd 20

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EnginEs & drivEs

23

repowering the past into the future

Lee Buchsbaum visited ASARCO’s Ray copper mine in Arizona to find out how the mine is repowering a fleet of Liebherr T282B haul trucks

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hile a decade ago many mines seemed to be competing to buy bigger and better equipment, now the mantra is finding ways to do more with less. For surface mines that require long truck hauls from the pit to the dump site, reducing fuel and maintenance costs are sure-fire ways to cut operating expenses. Another is repowering ageing trucks instead of replacing the trucks entirely. At ASARCO’s Ray mine, a large copper operation in Arizona, US, the team has found a way to do all three and come out ahead. The Ray mine is one of the world’s largest open-pit copper mines. It was established by the Kennecott Copper Corp, on the site of the towns of Ray and Sonora, and was later purchased by Asarco in 1986. Currently excavating an average of 223,000t/y of copper-, silver- and molybdenum-bearing ore from the open pit, Ray relies on a broad range of haulage equipment – reflective of years of different management perspectives on equipment and maintenance practices – to move overburden and ore alike. “We started off with a Komatsu 830E 214t fleet. Those trucks have been here for 20-25 years. Currently our mine equipment relies on a fleet of 21 Liebherr T282B 363t haul trucks. We used to have 22 Komatsus, but due to

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the age of the fleet, we’re down to only nine running units today,” says Keith Kenyon, maintenance superintendent at ASARCO Ray. With over 21 years under his belt at the mine, Kenyon has risen through the ranks from a labourer to now the maintenance general supervisor, running one of the departments he used to work within. During that time he has had personal experience with each one of those vehicles, and has forged strong relationships with all of his suppliers and original equipment manufacturers (OEMs). Dispatched by Ray’s MineCare system, the mine plan calls for all haulage equipment, regardless of the engine type, to be deployed on every haul road and in all weather conditions. “Our 21 Liebherr trucks each have an average 20,000 to 45,000 hours on the clock, while the Komatsu units average 120,000 hours and higher,” says

Kenyon. Ray’s three Caterpillar 793B 214t trucks also have over 100,000 operating hours apiece. Though each machine operates a little differently, Kenyon hesitates to simply pit brand against brand as he evaluates future steps. “To compare an engine is to compare a manufacturer,” explains Kenyon. “But it’s really not the manufacturer that’s critical; it’s about how their equipment is supported. If you have a team of engineers, product sales managers and service technicians that can support a fleet to the extent where you can get availability to a certainty, that’s where you’re going to want to go.” As the original engines in the Liebherr trucks reach their end of life, Ray has recently initiated a repower project to swap out the original Detroit Diesel/MTU engines with smaller, lighter Cummins models instead. The initial few months of tests have

The T282B Originally assembled at the Liebherr Mining Equipment Co production facility in Newport News, Virginia, the Liebherr T282B is an ultra-class, rigid frame, two-axle, diesel-electric AC-powertrain haul truck. It is Liebherr’s highest payload-capacity haul truck. The model is available with two

different diesel engines: a 2,722kW 90L MTU 20V 4000 series, or the 2,610kW 78L Cummins QSK 78 V18 engine. The diesel engine of choice is coupled to a Siemens-Liebherr AC electric drive system. Fully loaded, the 15.3m-long, 600t T282B can achieve a top speed of 64km/h (40mph). The truck has a fuel capacity of 4,732L.

The Ray copper mine has 21 Liebherr T282B haul trucks, each of which has completed between 20,000 and 45,000 hours of operation

“The repower project at Ray is unique in that it is the first one done with a Cummins QSK60series engine at a copper mine”

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EnginEs & drivEs

Dispatched by Ray’s MineCare system, the mine plan calls for all haulage equipment, regardless of the engine type, to be deployed on every haul road and in all weather conditions

The Liebherr T282B trucks at Ray are returned to service as soon as each repower is complete

resulted in more fuel efficiency, quieter running and no reduction in either reliability or service.

To rEpowEr or noT? In many cases, repowering an older truck can be more economical than buying a new one, but the decision comes down to what standard and purpose the repower engine is going to have and what the mine’s needs are. “The costs of buying a new truck are extraordinary compared with the cost of maintenance of a repowered vehicle, as well as repairs on most rebuilt trucks,” says Kenyon. As Kenyon and company investigated their options for repowering some of the Liebherr T282s, they based their decision on the ability to find a viable, cost-effec-

tive piece of equipment that was both environmentally friendly and safe to run for all operators. In the initial phase, the Ray mine is repowering four of its Liebherr fleet, changing the engines from 20V MTU models to V16 Cummins QSK60 engines rated at 2,124kW. “The truck we are currently repowering is a 20,000-hour truck. The engine is right at the end of its life. The reason we are doing this is to optimise fuel consumption,” explains Kenyon. “We are also moving forward because of the increased environmental conditions and safety benefits on offer for the operators. The environmental aspects include lower nitrogen oxide (NOx) and particulate matter levels. In terms of worker safety, the engine is now running much more quietly. Having a lower decibel range further optimises conditions for the operator.” The ideal engine size for each truck is selected depending on the mine site and application requirements. “You have to get into standard performance ratings such as time on grade, recycle times; compare the horsepower rating of different models, performance rating and maintenance schedule. That’s where you make your determination,” says Kenyon. Overall engine life is partially measured by the amount of fuel burnt. Generally speaking, the fuel consumption of trucks in most open-pit copper and gold mines is very similar; both are deep, hard-rock operations that, either by design or default, require their haul fleet to spend long times navigating often steep grades. The additional amount of energy expended to perform at the same level as say, a coal mine, requires a higher rate of fuel burn, resulting in a shorter life cycle. “With times a bit lean for the industry, the emphasis now is on extending the life of all haul-truck components,

including the engine. Though a manufacturer might suggest the lifetime of a truck is 75,000 hours, some mines go through two or three engines during that time. The overall thinking should be about the lifecycle cost of an engine,” says Kevin Spiller, vice-president of mining at Cummins Rocky Mountain, the Cummins-owned distributor serving the Rocky Mountain region. To do a repower, one may actually spend more than if a new version of the original engine were dropped in. “You’ve got to modify the frame, intake, exhaust and wiring, but you’re going to keep the truck another 60-70,000 hours. You’ve got to consider all fuel, maintenance and lifecycle costs and what you’ll be saving over time, not just the upfront engine costs,” adds Spiller. Of course, fuel is the highest cost centre for virtually every mine, hence fuel burn and performance are key issues. The engines of large and ultra-class haul trucks such as the Liebherr T282 burn roughly 50 gallons of fuel (190L) in an hour. At US$3 per gallon, that’s at least US$150 an hour running cost. Any savings there could be quite significant. The repower project at Ray is unique in that it is the first one done with a Cummins QSK60-series engine at a copper mine. “We’ve done a bunch of repowers in coal. They can manage with less horsepower, and are more economical afterwards. But swapping out the engine of the T282 Liebherrs at Ray, that’s unique worldwide,” continues Spiller.

prEvEnTaTivE mainTEnancE Given the extreme heat at the Ray mine, as well as the tough conditions and long hauls, preventative maintenance (PM) is a key part of the mine’s reliability strategy. “Our PM bay and our backlog facilities play a huge role in what we can do,” explains Kenyon. “The load factors out here average 34-35% and each condition is different. The ambient temperatures can run to nearly 60ºC in the middle of summer. With our trucks running long hauls, PM is critical to making sure everything operates at optimal levels. “With the fleet itself, we’ve gone through additional coolers and fan tests, but the question we always ask when something fails is: ‘how well did we maintain that piece of equipment?’ Having a brand new engine in the haul trucks allows a new cycle of planned maintenance that, hopefully, can further extend the life of each vehicle.” Every engine manufacturer also

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EnginEs & drivEs

recommends a maintenance schedule. “On our Cummins product we calculate what we think the engine life will be, and that determines the engine’s midlife as well. The midlife becomes a scheduled maintenance item; we change the fuel injectors, check the turbochargers, vibration dampers, water pump and fuel pump. That’s really the only scheduled work we do to the Cummins engine,” says Brad Scow, general manager of mining at Cummins Rocky Mountain. Additionally, there are also two ‘C’ checks that Cummins performs, but there is no repair work involved in these. C checks are done at 1,500 hours after the engines are put into service, and then 1,500 hours after the ‘D’ check at engine mid-life. They involve a load test, a visual inspection, a collection of fluids, and an overall review of engine conditions. “If you compare that schedule with what other manufacturers do, there may be four or five of these types of events that take place during an engine’s life. If you total up the costs, there is a very significant difference,” says Scow. “Such costs become a factor in final decision points. “When we talk about maintenance,

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there are two aspects: regular maintenance and regular interval maintenance throughout a product’s life. There’s a substantial cost difference between these points as well,” comments Scow. “Though now we’re swapping in Cummins QSK60 engines, that does not eliminate future options for other MTU 20V engines as well. We utilise and maintain relationships with all manufacturers; Liebherr itself played a huge role in making this repower project viable. It’s a joint effort between the OEMs and ourselves”.

ThE rEpowEr procEss The actual process to approve the repower programme began three years ago when several members of the Cummins sales and support team approached Kenyon to discuss better case scenarios for extending their equipment life. “It took us a bit to go through the process, beginning with working through some numbers, doing some planning and evaluations of various strategies,” says Kenyon. Once Scow and Kenyon had an operating plan, they worked with mine management to get acceptance and draw up the necessary operating

agreements, while making sure that there would be a good return on investment. Repowering a haul truck is an extensive process. “We have leaned on Cummins heavily to come up with a design and application. They, in turn, have worked with Liebherr and other third parties to put together a turnkey solution,” explains Kenyon. According to Scow, the repower process involves converting the engine mounts in the truck sub-frame. From there, the cooling-system plumbing, the exhaust and the intake plumbing are also converted. Then, a technician needs to convert the electrical interface to

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EnginEs & drivEs

properly match the engine with the truck control system. “To ensure that the engine properly fits the application, a great deal of engineering and testing is required. Each system needs specific attention, and the engine mounting is critical, as we do not alter the position of the main traction alternator,” Scow says. Some original OEM parts, such as the drivelines and duct work, also remain unchanged from when the original engine was installed. However, in this case additional shrouding was installed to accommodate the smaller engine size. “Once that is done, we go through a series of cooling-system, airflow and exhaust tests to ensure that all is within specifications once the engine has been installed. It’s a relatively involved process,” he continues. At the front end, a large percentage of the work is done on paper to

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determine the size and dimensions of what will be needed to fit the Cummins engine to the frame. Cummins’ team pre-builds the entire module in its nearby shop in Avondale, Arizona. “That greatly reduces the time we need to have the truck down,” says Scow. In total, it requires about three days of downtime for the truck to remove the existing engine, install the new Cummins engine and get it ready to run. “We’re looking to improve that. The first repower always starts the learning curve. We’re getting better with each repower,” says Scow. Afterwards, the rebuilt trucks go right back into the fleet and resume their normal duty cycles.

Burning lEss fuEl Since the repower project only began in May, there are still uncertainties about how far the initiative will go, but there

have already been some rewards, especially in fuel savings. “So far we have an 8.6% fuel saving based on gallons used per hour over a monthly basis. Haul truck 427, the first of the repowers, ran in May for 530 hours with a fuel burn of 23,900 gallons (90,470L). Each ton hauled cost US$0.08 in fuel consumption, and 45.3 gallons (171.5L) of fuel were used per hour. Those numbers are remarkable,” comments Kenyon. Ray’s team began seeing these fuel savings within the first 30 days of operation. However, the mine still has an unrealised saving that it hopes to capture through a 60% reduction in standard maintenance schedules. “We are still looking at the cost of the engine and the repower, and what the operating cost reduction will be. The focus of the repower project was to reduce the maintenance and rebuilding of components, but the fuel saving has been a nice surprise,” says Kenyon. Besides fuel efficiency, one of the key benefits for the operator has been the change in noise. “They’re very pleased with those changes. It’s so quiet, some operators were initially concerned whether or not the truck was running. The only downside thus far has been a slight response concern, but Cummins and our teams are working on fixing that aspect,” Kenyon adds. Additionally, the repowered engine weighs quite a bit less. Reducing the overall weight of the truck by 4t helps preserve its front suspension system. The repowers are performing better too. Kenyon says: “Our engineering group initially estimated that the repowered trucks would run slower on grades,

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For the Ray repowering project, Cummins’ team pre-builds the entire engine module at its Avondale, Arizona, facility

“Our engineering group estimated that the repowered trucks would run slower on grades, but actually they are running over 0.8mph faster uphill”

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EnginEs & drivEs

“That’s why we rely on resources such as Cummins and MTU to give us industry standard solutions”

but actually they are running over 0.8mph faster uphill loaded. Increasing the engine revolutions per minute from 1,950 has provided us a cleaner current, in turn giving us a better run.” The fact that the Cummins repower helps the mine to achieve new US Environmental Protection Agency (EPA) emissions standards for off-road vehicles is another important benefit. The repower engines are EPA Tier 2 compliant, whereas the previous engines were at Tier 01 or Tier 1 standards. “That’s why we rely on resources such as Cummins and MTU to give us industry standard solutions,” says Kenyon. “Any opportunity to advance our fleet performance while simultaneously lowering NOx and particulate matter is a real benefit.”

For ASARCO, future repower projects depend on the safety, environmental aspects and return on investment. “The fleet review is a continuous task. Having the ability to reduce noise levels for the operator is a huge contributing factor for future repowers. If we determine this is a measurable benefit, then we will move forward faster. Reducing our environmental footprint is equally important,” adds Kenyon. Cummins’ product support is key for Kenyon’s team, especially when it comes to maintenance and ensuring operational reliability. “They support us 110%,” he comments. “For us at the mine, Cummins is actually Brad Scow. He’s been able to show us the development processes for this repower project and has given us all the information we need

to make it happen successfully.” Though it is too early to determine how much the repowers will add to the long-term productivity of the trucks, Kenyon and crew expect the new engines to last (based on fuel burn rates) at least as long as the original engines. But in the end, these types of projects come down to one thing for Kenyon: “It doesn’t matter who the manufacturer of any product is, it’s how they can support you and your fleet that matters.” As this issue went to press, two Liebherr repowers had been completed at the Ray mine with a third scheduled for repowering in September, and a fourth in the pipeline. ASARCO will evaluate the repowered units this year, and make a decision early next year whether to repower the remaining 17 units in the mine’s fleet.

Repowers: a second opinion The MTU series 4000 engine

“Competition between us and other companies is good. It helps us all become stronger and provide better solutions”

Of course, Cummins is but one of many companies working in a highly competitive field to repower mining haul-truck fleets worldwide. MTU, formerly Detroit Diesel and now part of Rolls-Royce Power Systems, is another leading manufacturer of off-highway diesel and petrol engines, and power-generation systems. With eight locations in the US, including two manufacturing facilities, MTU America has a firm presence in this market, and is one of the dominant repower companies globally. Like Cummins, MTU is also looking forward to opportunities to repower ageing fleets of haul trucks. MTU’s advantage is that, since most Liebherr T282 trucks come out of the factory already equipped with an MTU engine, there’s a good chance customers will choose to stay with the power plant they know and have come to understand. “If a given mine has experience with a particular power plant, they know they can save on fuel and stay with the same maintenance practices. If you improve the fuel consumption or the horsepower by only a couple of percentage points, those costs savings can be significant,” says Scott Woodruff, MTU’s director of industrial engine sales and head of the company’s mining sales division.

MTU is also proactively moving to capture a piece of the international repower market for trucks such as the Liebherr T282. “As a 400-ton truck, the standard configuration is 3,650hp. We offer a variety of engines up to a 4,023hp model,” explains Woodruff. “The power of a given truck at a given mine should be based around how the mine profile is designed. The truck is designed to match the loader or excavator, and most mines match trucks and excavators according to tried and tested methods of transporting overburden and product,” he adds. Worldwide, MTU performs lots of repowers. “We are regularly contacted by mines looking for repower solutions,” says Woodruff. “As a result, the solutions that we present to mines can save them quite a bit of money.” As a vehicle ages, mines will often choose to refurbish their trucks, including changing the power plant. “During times of capital conservation, mines can elect to refurbish equipment for much less cost than new purchases. Our job is to help miners improve and update their assets so that they can keep them running for another 5-10 years depending on the mining cycle and their ore production and projections,” says Woodruff. As a management team decides which direction to go in, often their choices really boil down to costs saved over time. This, of course, includes service. “If you have better service or support structures, that may help a mine choose your product over another. But competition between us and other companies is good. It helps us all become stronger and provide better solutions for our customers,” says Woodruff. To help a mine decide which direction to go in as a truck starts to age, it is important to understand how the company runs its mine. “That indicates which truck or engine is right for them. We also need to know what their expectations are, and then we can spend our time focusing on achieving the right improvements,” explains Woodruff. “The bottom line is that we’re here to help our customers. We pride ourselves on support and have a wide breadth of knowledge that allows us to appreciate the perspective of the miners and respect their practices and their solutions,” says Woodruff. “We’re working to help create solutions and help our customers solve their problems.”

October 2014 Engines_MM1410.indd 30

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EnginEs & DrivEs

Boliden Tara is among Europe’s first mines to employ Stage IV/Tier IV technology in its underground LHDs and haul trucks

Sandvik has partnered with engine supplier Volvo Penta to achieve major reductions in NOx and DPM emissions

Ultra efficient Sandvik reports on the performance of its trucks and loaders equipped with new ultra-low emission engines at Boliden’s Tara mine

A

s awareness grows about the health impacts of DPM and other harmful engine emissions, regulators are introducing tough new environmental regulations. In response, mine operators are employing the latest ultra-low emissions diesel-engine technology in their underground mobile fleets. Brendan Anderson is head of the mobile equipment department at Boliden’s Tara Mine in Ireland, Europe’s largest zinc operation. He says engine technology is playing an increasingly important role in equipment selection. “That’s one of the key things we consider nowadays,” he says. “We look

at a lot of criteria but engine technology is up there, especially the emissions and particulate from the equipment. It’s not just about how much volume a truck can move or how fast it can move it. It’s about how clean the engines powering them are. Given our need to minimise underground emissions as much as possible, the best engine technology is essential.” Pat Hanratty is the senior ventilation engineer at Tara, and says that ventilating such a large underground operation is no easy feat. “We commit to our employees to work on reducing emissions and increasing ventilation to improve their health,” Hanratty says. The mine ventilation system has a maximum capacity of more than 1,000m3/sec and Boliden has made large capital investments to improve the total volume of air passing through the mine – particularly in the deepest areas one kilometre down. Hanratty says improving conditions for workers underground requires a combination of optimum ventilation volumes, the best available engines, the cleanest possible fuel and a strong maintenance programme. “Our trucks and loaders are big, and we need to have the best available technology in order to keep our people safe and healthy, and comply with the very stringent European regulations,”

Hanratty says. “That’s where Sandvik has been a really good partner for us. Early on, we got TierI IV/Stage IIIB engines in our Sandvik LH517s and we were very pleased with the reduced emissions those provided.” Boliden Tara is among Europe’s first mines to employ Stage IV/Tier IV technology in its underground loaders and haul trucks. The mine recently replaced a Tier IV interim engine in a Sandvik TH550 truck with a Tier IV Final, and a Sandvik LH517 loader is also thriving with a Tier IV Final engine. Both engines recently surpassed the 1,000-hour mark. “The Stage IV/Tier IV engines take things to another level,” Hanratty says. “We’re proud to once again be early adopters of these ultralow emissions engines. It’s to the betterment of everybody working underground. You get better productivity when people have cleaner air and a workplace in which they can be more efficient. “We’ve found over the years as we’ve developed that when you reach the limits of your current infrastructure and then you get an opportunity to bring in a new return air raise, and you suddenly improve the ventilation in an area it’s a dramatic improvement in morale in that area. Production increases. “Cost-benefit wise it absolutely pays

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EnginEs & DrivEs

to make sure that you can get the best environment for the people that you have working there.” Sandvik has partnered with engine supplier Volvo Penta for several years to help mine operators achieve major reductions in NOx and DPM emissions for its underground loaders and haul trucks. “We used to get reports from our operators about equipment working in a smoky environment,” Anderson says. “We just don’t have that now with the newer Sandviks. The lads will tell us that with the newer Sandvik trucks and the loader, the emissions level they notice is minimal in comparison to others. The Sandvik equipment is just at the moment so much better. The Volvo technology is so much better.” By the end of 2014, Sandvik aims to have all its underground load-and-haul fleet models sold in Europe powered by the ultra-low emission diesels, collectively referred to as Stage IV/Tier IV engines after the relevant European Union Euro IV and US legislative requirements. The engines have been required for the on-highway truck industry in the EU since 2013, and during 2014 it is being mandated for certain sections of the off-highway market, covering construction equipment and some mining equipment, including underground products. Anderson estimates that of the 300-odd pieces of equipment underground, less than 10% of those are burning 80% of the fuel. “A haul truck or a loader down there is burning a sizeable amount of fuel,” he says. “They’re the ones that can create the most emissions.” Tara has initiated efforts to quantify the benefits of the cleaner engine technology. The mine uses a MAHA MPM-4M diesel particulate analyser as well as an ECOM-AC instrument in its workshops to measure CO2, NO and NO2 levels different pieces of equipment produce. “Testing for diesel particulate matter is something that all operators are going to have to find out how to do best,” Hanratty says. “We really have to be vigilant, but it’s not an easy thing to measure in the ambient atmosphere. We know the polluters are the diesel engines and we feel we’re going about establishing the prevailing gas levels in the best possible ways.” Tara was the first mining operation in Ireland to adopt ULSD, which allowed the use of Stage IV/Tier IV engines with selective catalytic reduction technology. This enabled the mine to reduce DPM

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and NOx emission levels without the need for diesel particulate filter regeneration and the associated increased maintenance. “The European commission and various governments having pushed so hard to bring emission levels down has driven engine manufacturers to invest in new technology and develop these even cleaner engines,” Anderson says. “It’s up to us as operators to push the OEMs to get those engines into their mobile equipment.”

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By the end of 2014, Sandvik aims to have all underground equipment powered by Stage IV/Tier IV engines

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ADVERTISER PROFILE

DigitalGlobe: Seeing a Better World™ DigitalGlobe is a leading global information and solution provider that owns and operates a constellation of high-resolution satellites. It is uniquely positioned to offer advanced imaging capabilities, a global infrastructure and state-of-the-art processing and computing centres that allow it to provide innovative solutions across its diverse customer base.

D

igitalGlobe’s purpose of ‘Seeing a Better World’ is dedicated to helping customers see the earth clearly and in new ways, enabling them to make our world a better place by saving lives, resources, and time. Further, DigitalGlobe anticipates its vision to “be the indispensable source of information about our changing planet” will be realised by creating and maintaining a living digital inventory of the land, which provides solutions for our interconnected global economy on micro, macro, and global scales. DigitalGlobe provides solutions to a broad spectrum of customers from international governments and mapping portals, to global oil & gas, and mining customers. Geospatial Big Data (GBD) and Analytics are the foundation for achieving its vision and enable it to continue to create innovative and essential solutions for its customers.

MINING INDUSTRY Despite a high global demand for mineral resources, a cyclic mineral market and increasingly scarce deposits result in mining continuing to be a high-risk industry. Success requires reducing operating costs, improving exploration data inputs, and staying ahead of environmental concerns and conflicts. Consider, also, the global nature of mining exploration and operations. We must go where the deposits exist, regardless of remoteness, inhospitable terrain, or challenging political situations. Fortunately, solutions to these

pre-permit conditions, resource development, boundary compliance, and restoration needed to return the site to pre-mine status.

DigitalGlobe: key information • Area of expertise: satellite imagery products and services

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• Project locations: worldwide • Assets include: advanced satellite constellation, processes, analysis

challenges are offered by DigitalGlobe’s constellation of remote sensing satellites. Here DigitalGlobe introduces the cost-effective value proposition for the mining industry. DigitalGlobe offers mining professionals the right information tools to help make better decisions earlier for exploration, operations, and environmental compliance. The ability to make decisions sooner and more efficiently can mean the difference between success and expensive failure. Today, satellite imagery and analysis are being used throughout the world, in every stage of the mining lifecycle, to plan exploration, perform daily operations, ensure environmental compliance and complete land reclamation. DigitalGlobe’s advanced solutions reduce the resources and time required to find extra extract, and remediate mineral resources. In addition to mapping pathfinder exploration minerals, which can indicate the presence of desired deposits, DigitalGlobe high-resolution satellite imagery also enables easy detection of existing vegetation, hydrology, population centers, soils, and infrastructure. DigitalGlobe can also evaluate

Today, DigitalGlobe offers a wide array of solutions to best accommodate customer budget and operational needs required to fully understand the competitive landscape of a given mine and manage its lifecycle more effectively. “Because satellite imagery complements field studies and on-site observations previously required for day-to-day and follow-up operations, the industry gains valuable insight and efficiencies about investments and operational impact, while enjoying significant cost savings”, says Bill Baugh, senior staff scientist for DigitalGlobe Product Development and Labs.

EXPLORATION, OPERATIONS, RECLAMATION DigitalGlobe can provide solutions to mining sites anywhere in the world, even in remote, mountainous, or hostile areas that would otherwise be costly or cost-prohibitive to research. With DigitalGlobe’s high-resolution mining maps, geologists can detect, study, and analyse topographic surface features along with geological data to predict subsurface geology and understand where to mine. DigitalGlobe mining solutions are designed to be seamlessly integrated into its customers’ operational and GIS software. A detailed base

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Above: mineral locations revealed using satellite imagery exploitation in Exploration – Cuprite, Nevada USA | AVIRIS | 3.7m | WorldView-3 SWIR Mineral Index Simulation map over real-world imagery allows geologists to extract features and see where best to drill, design and construct infrastructure such as buildings, roads, pipelines, water resources and utilities. DigitalGlobe’s solutions can also provide a historical perspective that easily integrates with the mine plan and models. Updates allow for detection, monitoring and quantifying changes over time. Mining operators can also protect their investments with accurate basemaps of ground assets. Mining and surrounding areas are reflected to the detailed level of individual tree species, and can easily be used to accurately represent regional mines, prospect and regional geological data. This allows for reduced costs for planned production, location of reserves, and restoration to be linked to prospective and active mine locations.

EXPLORATION Alteration mapping at the scale of artisanal DigitalGlobe’s super-spectral sensors give mining professionals global SWIR-based alteration mapping at the scale of artisanal mining, enabling exploration remote sensing that allows you to “see between the trees”. This capability provides benefits that facilitate better decision making – saving time, resources and money. Remote sensing technology has been a well-recognised medium for mineral prospecting, but SWIR technology provides the ability to indicate “pathfinder” minerals which are present and indicative of related valuable deposits such as mineral ore; while possible environmental diagnostic minerals (including jarosite, alunite, and kaolinite) could be used as proxies for pH. “Not only is the SWIR range of DigitalGlobe’s satellites better for exploration, it hasn’t been available since ASTER SWIR failed in 2008,” says Bill Baugh, senior staff scientist at DigitalGlobe. SWIR is really the new sweet spot for looking at rocks. So, although WorldView-3 (like ASTER), is not specifically able to identify individual minerals (this requires hyperspectral systems), they are able identify the presence of these

“pathfinders” of broader mineral groups, which lead us to desired deposits. “A lot of times there are small geological structures that contain deposits, sometimes only a few metres in size,” says Bill. “For example, a rare-earth mine in California has ‘stringers’ that are only 3-4m wide – yet contain valuable deposits.” “The SWIR and CAVIS bands on WorldView-3 are designed to enable new and unique applications for the mining industry, such as mineral identification. “The satellite’s ability to identify different rock types, weathering regimes and surface materials, including their mineralogy and their alteration signatures, will prove economically valuable to mining operators through all stages of the lifecycle,” says Dr Kumar Navulur, DigitalGlobe Senior Director of Next Generation Products.

MONITORING MINING OPERATIONS Because satellite-based solutions minimise, complement, and/or eliminate much of the onsite field study previously required for day-to-day and follow-up operations, the industry gains valuable insight and efficiencies about investments and operational impact, while enjoying significant cost savings.

ENVIRONMENTAL IMPACT ASSESSMENT DigitalGlobe solutions also enable mining professionals to monitor and assess the impact of mining a habitat, as well as document restoration activity to government standards. The company’s solutions are effective tools to quantify and monitor vegetation and disturbance over time and are efficient and cost-effective for both underground and open-pit mining. A well-developed plan minimises the impact of mining activities on the immediate environment, neighbouring communities and long-term land capability. DigitalGlobe solutions for the mining industry can help increase efficiencies and improve your bottom line. To learn more about how you can save time and resources, visit www.digitalglobe.com/mining-solutions, contact us at +1 800 496 1225, or email info@digitalglobe.com.

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Surface minerS

Skimming the top Ailbhe Goodbody looks at the benefits of using surface miners, and at the latest developments and technologies in the area

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“Surface miners cut, crush and load the material in one pass, meaning a single machine completes the job of many different pieces of equipment”

surface miner is a mobile machine with a mechanically driven cutting drum. Surface miners are particularly suitable for greenfield applications where drilling and blasting is not an option due to environmental reasons and safety concerns. However, Flavio Villa, chief engineer – trencher division at Tesmec, notes: “Conventional drilling and blasting methods are still the most widely used excavation methods in quarries and open-pit mining operations, and in many cases they remain the most productive and cost-effective techniques.” There are a number of advantages to using surface miners in suitable conditions, typically flat, shallow-lying ore seams. Surface miners cut, crush and load the material in one pass, meaning that a single machine completes the job of many different pieces of equipment. The mining operation thus becomes simple and economically efficient, because there is no need to co-ordinate different sub-processes. The investment costs in surface miners are also considerably lower than those required for conventional mining equipment. Surface miners produce a small, consistent product size that can be loaded easily into trucks, so crushing the material in a separate work step is dispensed with. By using surface miners, a mine can eliminate the extra step of breaking down the product further and can use smaller trucks and loaders, which saves on overall long-term service costs.

It also removes the need for a primary crusher. Chris Lynch, sales manager, specialty excavation at Vermeer, says: “In a drill-and-blast operation, you will get everything from small fines to giant boulders. A primary crusher is required, followed by a secondary crusher in order to get the consistent size necessary for transport. In a surface-mining application, you get the size you need immediately. Eliminating the primary crusher alleviates a lot of cost because it is typically the most expensive piece of equipment – from a cost-of-operation standpoint – in a mine.” Frank Van der Hilst, international territory manager, surface miners at American Augers-Trencor, adds: “In mines or quarries where production needs to be extended past the primary crusher’s capacity, the use of surface miners will allow the end user to rapidly set up a new mining area with very minimal infrastructure requirements, reducing start-up cost.” Surface miners remove the requirement for drilling and blasting, as they replace this part of the mining process completely. If blasting is prohibited because of the resulting vibrations or noise and dust emissions, surface miners can be employed to mine the material economically. Furthermore, using drilling and blasting can also result in fires in coal mines, as the material is highly flammable – as a result, surface mining can increase safety levels at these mines. Lynch explains: “We are seeing not only tighter regulations surrounding that, but additionally we are finding that mines are growing to the point where they cannot drill and blast any more, so they need alternative methods of mining.” Villa says: “The use of explosives is subject to restrictive regulations, controls and limitations throughout the world, especially in politically unstable countries. Environmental constraint can

Integration There is potential for surface miners to be integrated with other mining technologies such as in-pit crushing and conveying (IPCC) systems, as a surface miner is already an in-pit crusher that simplifies the mining process and makes drilling, blasting and in-pit primary crushing unnecessary. Lynch says: “It can be used in mines where you need to get production going, yet don’t have the infrastructure to handle primary crushing. For

instance, a mine can utilise surface miners to go in with mobile crushers in order to go to market immediately rather than waiting to build a primary crusher, which can take years.” Schimm adds: “We see surface miners in combination with a conveyor as a very attractive alternative to IPCC systems. Since the surface miner produces already crushed, conveyable material, there is no in-pit crushing necessary.”

also make blasting uneconomical or undesirable.” Selective mining is another benefit, as surface miners can separate certain high-grade ores during the mining process, helping to avoid the dilution of ore quality. Selective mining gives the operator the opportunity to select and separate out the different ore qualities and increase the mine’s profitability. Bernhard Schimm, product manager, mining division at Wirtgen, comments: “The machines’ adjustable cutting depth allows even thin seams to be mined selectively and with high purity, thus contributing to better exploitation of the mineral deposit – in surface mining, up to 95%; conventional extraction, approximately 70%. Therefore less land is required and less overburden handling per tonne of raw material.” Selective mining can also result in an improved quality of the useful mineral mined, which entails lower processing costs.

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Surface minerS

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Wirtgen surface miners can load the cut material directly onto trucks, such as the 4200 SM shown here at an Australian iron-ore mine. The belt can be pivoted through 90° on either side and adjusted in height

What’s available?

There are a number of companies that manufacture surface miners for the global mining industry. Additional manufacturers not detailed below include Larsen & Toubro and Tenova TAKRAF. TeSmec The first Tesmec Rock Hawg was built in 2003, when a drum attachment was adapted to a Tesmec trencher. There are now two models of surface miners available: the 1150XHD Rock Hawg is a 50t machine powered by a 328kW Cat C13 engine that can excavate strips 3,120mm wide and up to 500mm deep; and the 1475 Rock Hawg is a 100t machine that is powered by a 470kW Cat C18 engine and is able to excavate strips 3,810mm wide and up to 600mm deep. Tesmec claims that the productivity of a single Rock Hawg can be more than three times that of an excavator of the same weight (or up to 15 times a 22.7t-class excavator) and a few Rock Hawg units can replace an entire fleet of excavators. Rock Hawg machines can

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excavate vertical side walls and side corners, thanks to wide, centrally-supported drums. The excavated pit in many cases will not need any further finishing through further excavation methods. Tesmec says that the shock and vibration from Rock Hawg excavation is negligible, and they generally produce a low amount of dust. In case the requested level of dispersed dust must be strictly limited, the machine can be equipped with an optional dust-suppressing system. Tesmec machines are equipped with a laser system to control digging depth and produce a gently inclined surface. The grade can be easily controlled on-site, and a one- or two-degree slope can be set in order to allow any emerging water to be drained.

The ‘flywheel gearbox’ is another feature of Tesmec surface miners. Villa says: “Since rock cutting is generally a discontinuous process, the flywheel gearbox is able to store energy for digging and instantaneously release it when required by the cutting process, delivering a torque peak up to several times the max torque of the hydraulic transmission. The flywheel gearbox also protects the hydraulic system from shocks and high pressure fluctuations.” In addition, the ‘reverse cut’ technology allows the surface miners’ teeth to hit the rock from the top down (rather than dragging it upwards to cut), increasing the efficiency of excavation. Villa advises: “As a rule of thumb, if the rock is somewhat fracturable, we say that changing from bottom-up to top-down

“The machines’ adjustable cutting depth allows even thin seams to be mined selectively and with high purity”

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Surface minerS

The Tesmec 1475 Rock Hawg can excavate strips 3,810mm wide and up to 600mm deep

“The benefits experienced due to the continuous development of Rock Hawg have been enormous... up to a 50% increase in productivity

Trencor offers three models of surface miner for the mining industry, including the T1460

cutting improves the production rate of the machine by up to 50%.” Another advanced system featured on the Rock Hawg is the Re.M remote monitoring system. All critical data (such as operating figures, engine condition, hydraulic system and diagnostic data) are regularly transmitted via a GPS system and stored in a dedicated server. Villa states: “The customer can monitor his fleet of machines from a laptop any time, anywhere. Tesmec service crews can access the Re.M for quicker troubleshooting and diagnostics, thus greatly minimising downtime.” Other new features of the Rock Hawg product line include drum stabilisers, a new drum, new picks lacing and an automatic laser for depth/slope control. Villa says: “The benefits experienced due to the continuous development of Rock Hawg have been enormous. The combined effect of the innovations have generated up to a 50% increase in productivity, compared with former models in the same job-site conditions, and the extension of the economical application range of the Rock Hawg.” The company’s main market is the Middle East, where Rock Hawgs are mainly used for limestone quarrying and bulk excavation. Additionally, two 1475 Rock Hawgs will start working at an open-pit coal mine in the next few months. North America is also an important market for Tesmec.

Trencor Trencor offers three models of surface miners for the mining industry, ranging between 470kW and 708kw in power. The main feature of the Trencor surface miners is the mechanical drive design. The company says that the mechanical powertrain is more powerful and reliable than a hydrostatic design, and is also less expensive to operate, less expensive to maintain, and requires fewer service hours. Van der Hilst comments: “The savings return to the owner comes from several different areas and over time amounts to a substantial cost saving. The mechanical powertrain incorporates a torque convertor that doubles the torque of the engine when the need arises in the cutting conditions. This, in combination with a high breakout force and the ability to maintain full horsepower in every gear, is the key to being able to successfully cut hard rock and achieve high production rates, which translates into profitability.” Due to its design, the mechanical powertrain of a Trencor surface miner requires only basic control systems that can be bypassed. Van der Hilst says: “Although technology is available to monitor certain functions through computers, we have found that customers prefer simple control systems that are more durable, easy to troubleshoot and repair by the maintenance staff on site. Mines are often located in remote areas and for this reason they want to minimise their dependence on the OEM. Ease of repair and uptime is key for every mining company.” Technology-wise, Trencor has not launched anything new in the last two years, but has focused on improving its existing design to further increase up-time and machine capabilities in harder more solid rock formations. Trencor carried out a very successful construction project in solid crystalline

limestone in Kuala Lumpur, Malaysia, last year that showed that the designed changes have lifted performance and durability. The project was for MMCGamuda at Pasar Raykat MRT station, where more than 300,000m3 of solid limestone ranging in unconfined compressive strengths between 90 and 240MPa with an average of 130-140MPa needed to be excavated for an underground station. At the moment, Trencor’s main markets for surface miners are in Asia, but the company has seen an increase in enquiries from other parts of the world as well. Van der Hilst suggests: “The awareness in the mining industry and the pressure from governments on mining companies to increase greenfield projects is growing.”

Vermeer The T1255III and T1655III Terrain Levelers are Vermeer’s primary surface-mining machines, and are the two models that mines are buying in numbers as primary production machines. However, Vermeer also provides a Terrain Leveler attachment for its T855III 246kW tractor. Vermeer says that its technology advantage is a patented tilt on the surface miners’ head. Lynch explains: “We are able to level the head in combination with GPS technology to provide a smooth floor and also control the grade of the floor. This is beneficial in areas that incur a lot of rain.” The Terrain Levelers serve as multipurpose machines – not only do they control the grade, but they can also dig trenches to control water. In addition, Terrain Levelers can cut a high vertical wall. This is an advantage because it helps with the architecture of the mine and allows the operation to extract as much ore as possible. Terrain Levelers can also be used for road maintenance, so they are very versatile machines. All of Vermeer’s machines use the TECPlus control system, which is a patented computer-based system that makes the machine easier to operate. It is also easier to train a new operator, which from an efficiency standpoint is very beneficial to a mine. The control system allows for the maximum amount of production from a machine. Earlier this year, Vermeer introduced a remote-control system that enables the operator to control and precisely manoeuvre the surface miner from a location up to 152m away. All functions can be performed via the remote-control panel, which is attached to a vest that is

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Surface minerS

The T1255III Terrain Leveler is one of Vermeer’s primary surfacemining machines

The Wirtgen Pick Inspection (WPI) system gives the machine operator a fast and simple overview of the degree of wear of the picks, allowing them to identify worn picks quickly

strapped onto the operator’s torso; the control panel lies flat in front of the operator with a metal frame around the outside to help provide support. From a personnel-management standpoint, this technology can help mines to save on labour costs and the costs associated with liability and insurance. Vermeer is also launching the next generation of the TEC Plus system to the market. SmartTEC is an on-board system that continually monitors the performance of the machine. It feeds information to either a remote site or to the operator in the cab and tells them over time how much product the machine has produced, how long it was idling, maintenance time and tramming. Lynch explains: “It’s a great service tool because it records performance and provides operational data on a daily, weekly or monthly basis – or over the life of the machine. The purpose of the software is to provide confidence to the machine operator and mine operators that they are getting the most productivity out of the machine.” Vermeer is focused on technology and how it can make the machines and their application more efficient. Lynch says: “GPS technology and telematics is the key to more productivity. If a mine has a good GPS map of an orebody, then it can be programmed into the machine to

make sure they are getting the ore and not the overburden or inner burden.” Vermeer has Terrain Levelers on every continent except Antarctica. They are used in mines all over the world extracting everything from hard iron ore, copper and gypsum to nickel, silver and coal. The company’s hot spots are Australia with iron ore and coal, and Chile. Australia and South America are the company’s main areas for growth. The company also has activity in Africa in the Democratic Republic of the Congo (DRC), with several machines at a Freeport-McMoRan mine that has some of the highest-grade copper in the world. Lynch notes: “It comes in veins mixed with lower-grade copper and waste material. It is very important for the company to selectively mine these high-grade orebodies. Because of the method our machines use, operators can visually see the separation and can sort by high grade, low grade and waste material.” Vermeer currently has a trial going on with Rio Tinto in eastern Australia, excavating coal. Lynch says: “We are working with the mine on several applications involving dust-suppression systems, GPS and horizon control, which is a way for the machine operator to visually detect when the cut goes from coal to waste material and back again.”

Wirtgen Surface miners from Wirtgen offer cutting widths ranging from 2.2m to 4.2m and cutting depths of between 20cm and 83cm. Wirtgen’s surface miners cover a scope of performance ranging from 100 to 3,000t/h. Wirtgen introduced a new system in February 2013 called Wirtgen Pick Inspection (WPI), which measures the wear of surface-miner cutting tools. It comprises eight very rapid measuring sensors, which are integrated in the cutting-drum compartment of the

surface miner and measure the degree of wear on the picks. Schimm explains: “Taking just one minute to complete, the measuring process can easily be carried out while changing trucks, thus avoiding downtime.” WPI is easy to operate; the measurement is fully automatic at the push of a button. A separate mobile end device, which forms part of the cutting drum, marks the worn pick in colour on its display. The result is displayed clearly with different colours, making it easier for operators and service technicians to plan the necessary service intervals based on the wear information for individual machines. The system also helps to ensure that the cutting tools can be used for the maximum length of time. Cutting technology is one of Wirtgen’s core competencies, and is one area where the company focuses its R&D efforts. It recently released the HT15 quick-change toolholder system, which simplifies the process of changing toolholders and shortens it by up to 60%. The automatic features are designed to minimise the time needed for tool replacement, and therefore machine stoppages. A purely batteryoperated hydraulic model of the tool extractor is available for surface miners. Wirtgen’s latest surface-miner model is the 2200 SM 3.8, which the company states has 25% higher productivity and 15% lower fuel consumption than previous models. It cuts soft rock with unconfined compressive strengths of up to 35MPa, such as coal or salt, depositing it in three windrows behind the machine. The first Wirtgen 2200 SM 3.8 surface miner is being used by contractor Xinjiang Jianyun Engineering Co at the Yihua Xinjiang Wucaiwan coal mine in the Chinese province of Xinjiang. Wirtgen’s surface miners are working globally in different applications with a variety of extraction materials. Coal mining is one of the company’s main markets, particularly in countries such as India, China, Russia, the US and Australia. Wirtgen also says that the coal-mining markets in Kazakhstan and South Africa are becoming increasingly important for it. Recent orders Wirtgen has received include a new 4200 SM for a coal mine in the US and a new 4200 SM for a phosphate mine in Peru. In addition, seven new 2500 SM units have been ordered for a limestone mine in Nigeria; following the successful use of seven Wirtgen 2500 SMs in the mine, the customer bought a further seven to extend capacity and expand the mine.

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Integrated skip conveying and crushing system Balanced-skip haulage systems are one of the mining industry’s most mature technologies. Now we offer the advantages of incline skips to those high-tonnage open pits where haul truck operating costs are reducing profitability. The capital and operating economics of our system are very compelling, with significant improvement of the green footprint. Up to

5,000 t/h

capacity

With this system, haul trucks have a short, flat haul before discharging their loads directly into a waiting skip. At the surface, the skip discharges into a gyratory crusher that – in turn – loads to an overland conveyor system for onward transport.

Patents Pending

ThyssenKrupp Industrial Solutions www.thyssenkrupp-industrial-solutions.com

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SNAPSHOT

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Fancy a cuppa? Cayeli Bakir Isletmeleri, a subsidiary of First Quantum Minerals, operates the largest underground metal mine in Turkey. The operation is fully mechanised and mines 1.3Mt/y of ore to produce 160,000t/y of copper concentrate and 88,000t/y of zinc concentrate. The mine is located in a valley close to the Black Sea on Turkey’s south coast that hosts fast-flowing rivers, lush vegetation and a wide variety of flowering plants. Traditional occupations for the local communities include fishing and widespread tea farming, as pictured here. Despite featuring a 600m-deep shaft, a 24,000t run-of-mine ore pad and a 3,750t/d mill as well as other significant infrastructure, the mine manages to blend surprisingly well into its natural surroundings. Photo: Murat Topal

Love photography? Each month Snapshot will feature the best image sent to us by MM’s readers. For a chance to have your image featured, send your photo plus a 100-word caption to: carly.leonida@miningmagazine.com

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sx-ew

Better designs produce winning results

Richard Roberts reports on the latest developments in solvent extraction and electrowinning Kipoi SX module in the Democratic Republic of the Congo: Africa has been a focus of activity for SX-EW plant designers and builders in recent times

“Commercial SX facility design has evolved over the past five decades with a number of types of mixer-settler and column arrangements tried and tested”

T

he days of solvent extraction (SX)/electrowinning (EW) having a revolutionary impact on the global minerals industry may be in the past, but significant refinements continue to affect plant design to produce vital efficiency and safety benefits, an international conference on solvent extraction in Germany has heard. Lee John, an expert in the field from South Africa’s DRA Mineral Projects, told the 20th International Solvent Extraction Conference (ISEC 2014) in Würzburg that state-of-the-art SX plant design is allowing for reconfiguration of piping in conventional mixer-settler setups to suit changes in processing requirements, or chemistry, as operations expand. This is boosting operational flexibility and performance, and also contributing to fire risk minimisation. “Commercial SX facility design has evolved over the past five decades, with a number of types of mixer-settler and column arrangements tried and tested in pilot and commercial operations,” John says. Some fundamentals, however, have not changed, and are often not properly addressed or even considered in some commercial operations, leading

to high-risk installations, possible catastrophic failure and/or fire. “Design improvements to the conventional mixer settler including flow distribution, picket fence designs based on CFD modelling, [and] smart piping layouts, combined with extensive practical experience, have resulted in numerous operating improvements such as higher unit capacities and lower reagent losses,” John explains. “These refined conventional mixer-settler designs have proved to be the best all-round performers for a wide range of SX duties in the minerals industry.” John says that modern SX designs also need to cater for the prevention of all possible sources of contamination. “Any such designs also need to be conservative,” he says. “Prevention of SX cross-contamination may involve diluent washing or activated carbon processing of raffinate prior to the next SX stage.” EW design and commissioning also needs to be “mindful of the relationship EW has with SX”, and steps must be taken to ensure an ongoing healthy synergy, especially for control of spent electrolyte.

“New SX extractants and associated technologies will develop over the coming years, but prior to successful commercialisation, the SX system should be verified against and designed for the many lessons already learnt in SX operation over the past five decades,” John explains. The ISEC 2014 paper compiled by John and the principal of Australian consultancy Miller Metallurgical Services (MMS), Graeme Miller, stated that minimalist SX-EW plant designs, which had reduced instrumentation levels and were “designed for self-regulation”, had evolved from multiple installations in new African copper and other mineral projects. “Such state-of-the-art designs include elements to minimise the chance of an SX fire, and preserve other assets nearby in the event of a fire,” John adds.

Back to Basics Heap leaching of oxide copper ores and cathode copper recovery by SX and EW is an established primary, low-cost hydrometallurgical copperrecovery method, with hydrometallurgy also developed and applied to sulphide ores and concentrates, such that SX-EW

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The right partner. The right chemical technologies. At just the right time. Being a partner to your mining operation is not just our profession, it’s our passion. We deliver leading chemical technology in Alumina Refining, Mineral Processing and Solvent Extraction—innovations powered by a rich history of efficiency and value. We provide onsite support, where our experienced team works right alongside you to resolve challenges with robust solutions. As a recognized global leader, we can offer you peace of mind through our commitment to steady, reliable product supply. Combined, working with us provides you an opportunity and a partnership you won’t find anywhere else. To learn more, please visit http://www.cytec.com/businesses/in-process-separation/mining-chemicals

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sx-ew

Kipoi SX tank farm and reagent area, which recovers dissolved copper from the PLS solution, ready for electro-winning

“Such stateof-the-art designs include elements to minimise the chance of an SX fire, and… preserve other assets nearby in the event of a fire”

accounts for more than 20% of total world copper output. SX generally refers to a process in which aqueous pregnant leach solution (PLS) is mixed vigorously with organic solvents, and copper is selectively recovered from PLS. The organic solvent is then separated and the copper stripped from it with a fresh acidic solution to produce a concentrated, relatively pure copper liquor suitable for EW or precipitation. EW then sees the copper-rich solution filtered to remove any organics, heated, and then passed through a series of electrolytic cells to form high-quality cathodes. International Copper Study Group data showed world copper-mine production rising by 30% to about 15Mt between 1997 and 2006, a period in which production by SX-EW reportedly surged by 63%. Latest data points to SX-EW production accounting for as much as a quarter of the 20Mt or so of global annual copper output. SX-EW was a vital factor in the revival of US copper-sector competitiveness in the 1980s before it became more influential in the growth of copper production in Chile and, increasingly now, in Africa. John and Miller say that fundamentals often still poorly addressed in SX design include: • Plant layout aimed at minimising piping and electrical routes, and simpler operability and lower capital cost; • Inter-stage piping and unit layout; • Design for re-configuration of the

• • • • • •

units if required due to chemistry or flows; Design for operability issues in commercial plants – extreme organic or aqueous flows needed to change mixer continuity; Material selection, earthing, piping, instrumentation and civils; Contamination and organic degradation from oxidation reaction in the closed electrolyte circuit; Crud removal access and crud-handling facilities; The positioning of SX plants relative to other SX plants, process plant and buildings that would be damaged or involved in the event of a SX fire; and Fire hazards created by static electricity generated via the flow of organic material (especially in plastic pipes).

John also notes that fire-risk management in SX plants has become far more heavily scrutinised due to the number and severity of fires in the past 15 years. “Poor layout and or selection of piping material have resulted in several major SX fires around the world,” he states. Two of these were at the Olympic Dam operation in South Australia. These were found to be the result of minimal compliance with the standards for control of static electricity”. “The diluent used in copper SX typically has a high flash point, and thus copper SX plants could be classified as non-hazardous areas,” says John. An industry survey by Miller found that more than 50% of copper SX plants are “unclassified or unrated for

electrical-apparatus fire initiation”. According to Miller, many of the advances made in the understanding and minimisation of fire risks in copper SX are directly transferrable to other SX plants including: • The use of fire-plume analysis to position other assets outside the fire-affected zone from an SX fire – this should be applied to all new SX plants; • Understanding and implementing the standards on static electricity generation and relaxation. The conductivity of uranium SX organic is two to three orders of magnitude higher than copper SX organic. This means that in theory the static electricity codes could be applied, but the risk of a static accumulation is in any case much lower; • Application of the appropriate hazardous-area rating codes. With the use of isodecanol, other alcohols or other modifiers in an SX plant, the effective flash point is often lowered and the plant must be hazardousrated appropriately; and • Attention to the detailed design of the mixer settlers and other elements to eliminate the generation of aerosols that could lower the effective flash point even further. John says that crud prevention and treatment continues to be another issue for producers. Acid leach processes commonly used in uranium, copper and other base-metal leaching can dissolve significant amounts of silica from ore. Along with suspended solids, dissolved SiO2 concentrations

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in the resulting PLS can range from a few hundred ppm up to several thousand ppm. “For this reason alone, SX circuits are best equipped with PLS clarification and silica-removal circuits, which should always be conservative in design to cope with plant upsets,” John explains. “No one has complained yet that the PLS feeding an SX plant is too low in silica and suspended solids, or that the crud-processing plant is not being utilised fully! “Crud and organic recovered from EW cells should under no circumstance be returned to crud processing or the SX circuit. The extractant has most likely been oxidised and chemically altered in the EW cell, and will only serve to create issues of crud, reduced chemical capacity of the SX organic and slow phase disengagement issues,” he adds. Meanwhile, commercial EW design has not changed to the same extent as SX design, over the same period, although there had been small progressive improvements. John explains: “An understanding of the interactions that EW has with SX under certain conditions has resulted in more specific operating and design criteria to maintain a healthy synergistic relationship between the two.”

Mixer-settler design John adds that conventional mixer-settler design has gone “full circle and is now fundamentally the same as used in uranium plants in the 1950s, albeit with many improvements”. Novel designs such as Krebs settlers, external organic depth control and pulsed columns have come and gone. After 50 years of innovation, the conventional mixer-settler design is still the most commonly implemented in the minerals industry today, according to John. “Traditional head-to-tail arrangements have been reconfigured with some smart piping and nozzle designs so that the mixers are all on the same side, resulting in considerable operability improvements as well as a reduction in electrical and piping reticulation,” he says. “The result is a reduced footprint and a reduced CAPEX of the plants. “Reverse Flow and the MMS SideFeed mixer settlers are now the most commonly used head-to-head arrangement. Better layouts with these arrangements facilitate reconfiguration of the units to suit any revised duty.” The most recent installations of

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SX-EW copper production has, and continues to have, a major impact on sector economics and product quality in North and South America, Africa and Australia

MMS-designed mixer settlers in Australia and Africa now incorporate piping designs to include the flexibility to change the duty of a mixer-settler unit should that need arise. John says the installations were reconfigurable so that mixer-settler units could be changed from, or to strip, wash or extract. “Being originally designed to be reconfigurable allows changes in piping that avoid the delays and costs associated with shutdowns for hot work [such as welding],” John explains. “Such piping also allows a mixer-settler unit to be converted easily and without the need for hot work, from a series unit to a parallel unit. In addition to these improvements, the modern mixer-settler units have superior flow distribution from the mixer into the settler.” He adds that advanced picket fence designs minimise turbulence and achieve better aqueous organic separation with lower entrainments. “The use of higher unit settler flow rates has resulted in an increase in organic depth to limit the space velocity,” John says. “The increased inventory costs are significant in the overall CAPEX profile.” Uranium, phosphate and nickel SX are the only major metal recovery SX operations where pulsed columns have competed with mixer settlers. The extraction kinetics of ion exchange extractants commonly used for uranium recovery are faster than those of the chelating oxime extractants used for copper recovery. This means that while column contactors are not considered for copper SX operations, they have been installed for the extraction stages in a limited number of uranium operations. “For uranium SX there is no technical

imperative for the use of columns,” John explains. “While columns have been used for the extraction stages of uranium SX plants, they have not to date been used in the stripping and scrubbing stages. There are examples where the use of columns in pilot plant stripping and scrubbing operations has met with difficulties due to the requirement of stage-by-stage pH control. “As a result, the scrubbing and stripping activities of base metals processes are all conducted in mixer settlers.” Olympic Dam was also the site of a significant instance of contamination of one SX extractant stream from another used at the same location. The operation has a sequential copper SX and uranium SX circuit. John told the conference in Germany that the problem was chloride transfer into the EW, resulting in pitting corrosion of stainless-steel cathodes which caused the copper to stick and prevented it from being easily stripped from the cathode. “The eventual culprit was found to be the uranium SX reagent that was entrained in the raffinate in such quantities that it was returning to the copper PLS via the leach and CCD circuit,” he says. “In the copper SX, the trace of uranium SX extractant was transferring the chloride to the EW electrolyte with disastrous consequences for the stainless steel cathodes. “The cause of the high losses was not purely entrainment but also physical transfer during start and stop transients. The column extraction system released much of the contactor organic contents to the raffinate tank on shutdown due to poorly sealing aqueous discharge valves.”

“An understanding of the interactions that EW has with SX has resulted in more specific operating and design criteria to maintain a healthy synergistic relationship between the two”

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UndERgRoUnd dEvElopMEnt

A prototype of CEMI’s canopy has been built and tested at MTI’s test mine in Sudbury, Ontario

Speedy delivery The fast and efficient exploitation of underground deposits is increasingly important for mining companies. Ailbhe Goodbody examines the reasons for this, and some of the latest technologies

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“The principal vision of the hard-rock mining industry is to have a roadheaderlike machine that is able to cut very hard rock”

apid development and faster access rates have become more important in the underground mining industry in recent years, with a growing interest in rapid-development technologies. As existing orebodies are being depleted, new orebodies must be discovered. Historically these have been greenfield discoveries with surface/openpit capability. With the depletion of existing pits, mining companies are forced to move toward underground operations, with bulk mining being the most economical way. Al Akerman, R&D programme director at the Centre for Excellence in Mining Innovation (CEMI), says: “However, [with caving techniques] mining cannot commence until the draw bells are created. As time is money, the quicker one can access the ore, the quicker the mining company will see a return.” The two main drivers behind this are development speed and tunnel quality. Uwe Restner, product line & sales support manager, hard-rock continuous mining at Sandvik, explains: “Tunneldevelopment speed can be directly related to a positive effect on the net present value of ore deposits, and tunnel quality ensures a high ore-extraction rate. The faster you develop tunnels, the faster the ore production can start and revenue can be generated. In the past, tunnels of bad quality simply collapsed and the ore got lost. This should be avoided by a higher tunnel quality ensured by mechanical excavation.” Advance rates in the mining industry

today are actually slower than they were in previous decades, due to a combination of factors. The main reason is the support requirements at depth to keep miners safe when compared with those needed for shallow deposits – mines are getting deeper, and as they get deeper, the stresses on the rock increase, leading to additional support being required. Akerman says: “Historically, support has been the slowest part of the process. Additionally, all processes are serially driven rather than having some of the processes done in parallel.” Mechanised development techniques have advantages over more traditional methods such as drill and blast, most notably the advantage of speed. However, there are currently some constraints in hard rock. Akerman states: “In Rio Tinto’s ‘Mine of the Future’ they see increases in advance rates being driven through mechanical excavation rather than the more conventional drill-and-blast methods in softer rock formations. In hard-rock mining, drill and blast are the only alternatives.” As a result, research into hard-rock cutting is increasingly important, with benefits including the ability to mechanically excavate very hard rock, allowing faster tunnel development and better tunnel quality. Restner says: “Generally, the entire hard-rock mining industry is aiming for rapid mine-development systems. In the past, the trend was going towards [tunnel boring machine] TBM-like systems, but recent trial operations have shown that such machines cannot really

be handled in underground mining environments. Consequently, the aim developed to smarter and more compact equipment and machines that are able to cut hard rock. “The principal vision of the hard-rock mining industry is to have a roadheaderlike machine that is able to cut very hard rock.” There are several companies working in the area of rapid development, some of which are detailed below.

CEMI CEMI has developed a portfolio of advance rate developments as part of its Rapid Development Project. To date, CEMI has built a canopy allowing various processes to be performed by creating a safe operating environment, using the canopy as temporary roof support. A prototype has been built and tested at MTI’s test mine in Sudbury, Ontario, Canada. Akerman comments: “From the favourable results, the work in early 2015 will be the functionality testing of the units in an underground test environment. Subsequent work will hinge on the development of a face machine capable of drilling and explosives loading in a single unit, moveable conveyors attached to ‘Hagg-style loaders’ and sizers capable of operating in the limited drift sizes we propose.”

CRCMInIng CRCMining is working with its mining and OEM members on a range of research-and-development projects to

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CRCMining’s ODC technology was licensed to Joy Global in 2006

solve current mining challenges as part of its research roadmap, with a 20-year vision for innovations and technologies to transform mining methods and processes. CRCMining’s oscillating disc cutter (ODC) is a technology for efficiently excavating hard rock to +250MPa. With relatively low input power, it is feasible to create compact, flexible mining equipment, as part of a continuous or semi-continuous mining system for hard-rock excavation in both surface and underground mining applications. Various configurations of the technology

might be single heading focused, with a focus on maximising advance rate for an access decline or more flexible roadheader-like versions capable of moving between headings. The outcome of more than 20 years of research, CRCMining’s ODC technology was licensed to Joy Global in 2006 and is now branded as DynaCut. ODC technology combines an undercutting approach (breaking the rock in tension) with high-frequency dynamic motion to efficiently break hard rock. The method requires much lower forces than those associated with conventional roller disc cutting, and avoids the application of picks, which have been shown to be inadequate beyond medium-strength rock (+80MPa). The gains for mining are potentially significant, with a shift away from batch to continuous approach, substantially changing the way mines are operated. The number of Dynacut mining machines applied to an operation would be less constrained by traditional ventilation limitations such as diesel particulates. Productivity and cost-improvement comparison estimates are difficult to describe due to the spectrum of

application possibilities. Broad predictions for productivity improvements in the order of 20%, plus up to 20% reduction in total mining cost are reasonable. Brad Neilson, vice-president of hard-rock mining at Joy Global, explains: “DynaCut is the key enabler for a hard-rock continuous mining system that is relatively small, flexible and inexpensive. Required forces to cut rock are reduced by approximately 80%. The DynaCut technology provides an opportunity to reduce risk to personnel and change the mining process, from a cyclical process with a lot of dead time, to a more continuous mining process that is relatively easy to automate.” Joy Global has been operating an ODC-based reef-mining machine for five years. Information from this project has been incorporated into the design and fabrication of a Dynacut machine that has been cutting rock for more than a year. Joy Global has been concentrating on testing its rig on really tough monzonite rock, with uniaxial compressive strength (UCS) in the order of 200MPa. The team has exceeded every internal benchmark. Cutting rates in material

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over 200MPa UCS are in excess of 15m3/h, and the life of the cutting unit has exceeded Joy Global’s internal commercialisation target of 100 hours. CRCMining states that its ongoing work with Joy Global will improve the understanding of the mechanism of rock breakage with the ODC method by experimental process and modelling. Neilson explains: “Joy Global continues to invest in DynaCut technology, with an acceleration to develop a commercial solution. 2014 delivered confirmation of breakthrough cutting rates and life of the cutting unit.

With the significant increase in cutting rates, we are focused on bit technology, material clearance and the product platform.” There is also a CRCMining project under way to examine the incorporation of very high-pressure water jets (89.6MPa) to the cutter/rock interface. CRCMining says that high-pressure water has been demonstrated to significantly improve performance and reduce wear in rock-cutting applications, but has not been directly applied to an ODC application. The Joy Global rig is an ideal opportunity for implementing such trials.

Sandvik is currently working on the detailed design of a rapid mine-development system, and plans to have a market launch in early 2018 after a one-year trial period to get proof of the reliability of the system. Sandvik could not give further details about the concept at this stage, but the company aims to create a rapid mine-development system that is able to smoothly and accurately excavate and support tunnels from 4x4m to 5x5m at a steady advance rate of 20m/d. The company is principally focused on making it a simple excavation machine concept, including the ability to perform rock-support installation simultaneously with cutting. Sandvik has also invested €5 million (US$6.5 million) in a new rock-cutting test rig, which will be ready for use by the December 2014 quarter and will support the development of cutting technology of the rapid mine-development system. Restner comments: “We really want to understand hard-rock cutting technology before we implement it into a mining or tunnel-development system.”

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Sandvik’s rockcutting test rig

“Mechanised development techniques have advantages over drill and blast”

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UndeRgRoUnd development

straight up Ailbhe Goodbody looks at the latest developments and projects in raise boring, shaft sinking and tunnel boring in the mining industry

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vertical shaft is an efficient way of accessing either a deep orebody or one situated below a ‘worked out’ open-pit mine. Alon Davidov, CEO of Shaft Sinkers, says: “Hoisting rock up a vertical mine shaft is by far the most costeffective method to get rock to the surface on a life-of-mine basis. It is more efficient than trucking rock to the surface via a decline and does not suffer from the substantial ventilation challenges that arise when using declines.” Raise boring and shaft sinking are the main methods of shaft excavation, and each method has its pros and cons; there are a number of factors that dictate which is chosen. These factors include, but are not limited to, access availability at top and bottom, geology and rock mechanics, end use and the life span of the shaft.

Raise boRing Generally, raise boring is used to develop ventilation raises for fresh and return airways and for ore and waste pass excavations. Larry Zuccherato, VP business development and international operations at Dumas, says: “There has also been an increasing trend towards raise boring for hoisting shafts – either excavated in a single pass to the desired diameter, or in conjunction with drill and blast as a two-pass system.” Raise boring’s main advantages are the speed and the quality of tunnel development, and it is also a relatively safe method. In competent ground, the circular bored hole produced is

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fundamentally a more stable design than a square or rectangular opening with respect to underground rock stresses. Generally, the shape also delivers better ventilation characteristics for airflow than the irregular rock profile that can result from a blasted rock wall. The latest trends in raise boring focus on bigger diameters, longer raises, high-capacity machines and directional drilling for pilot holes. In addition, with many new block-cave mines being developed, the need for boxhole raises is increasing – Redpath’s South American operations in Chile notes that Codelco is moving forward larger-diameter blindhole slots for larger cave production blasts (2m diameter and up to 70m in length).

new products and projects Dumas has a joint-venture partnership for raise boring with Bergteamet, which has several active raise-boring projects for clients including Norsk Gronnkraft in Kvemma, Norway, Leonhard Nilsen & Sønner in Rössåga, Norway, Boliden in Tara, Ireland, and Hindustan Zinc in India. Herrenknecht’s boxhole boring machine (BBM) was recently developed for the excavation of vertical and inclined slot holes in underground mines. The prototype was tested in 2011, and now there are five BBMs successfully operating in Australia and Chile. The company’s raise-boring rigs have drilled both production and ventilation shafts in mines in Bolivia, Chile, Italy and the US. Redpath has expanded its machine

offerings to meet growing demand at block-cave mines. It now offers Redbore 30, 40 and 50 machines in boxhole form, which it states allows each client to select the optimal machine for their application. Sandvik recently launched new cutters (CMR 41/77, CMR 52/77, CMR 501) to improve overall performance, including the penetration rate and service life of raise borers. Sandvik reaming heads and cutters are used for ventilation raises, ore passes and slot raises in various different global raise-boring projects. TRB Raise Borers’ new Rhino 100HM raise borer, which uses Sandvik tools, was recently launched in two different mines. It is a highly mobile slot-hole boring machine utilising raise-boring technology that is ideal for mines using block or sub-level caving methods. Using only one operator, mines can substantially improve stope development times; from 2-3 weeks (long-hole drills only) to 5-6 days using Rhino 100HM and long-hole drills working together. Jarko Salo, managing director at TRB-Raise Borers, notes: “It has been discovered that more than three long-hole drills are required to keep up with the Rhino – otherwise they become the bottleneck in the mine production.” TRB Raise Borers has also launched a boxhole borer and some prototype downhole raise borers that use water for flushing and conveying the cut material out of the borehole.

shaft sinking Blind or conventional shaft sinking is the most common way to excavate a shaft, and it can be done as the initial mine access opening or before the primary mine infrastructure is in place. In addition, where ground freezing and grouting techniques are required, shaft sinking is the preferred method to advance through adverse conditions, especially if specialty shaft liners are required. Davidov says: “The latest trends in shaft sinking have focused on ‘doing more with less’ while providing a safer environment with non-concurrent activities in the sinking shaft. As a result, developing and improving mechanised sinking methods remains a long-term priority for the industry.”

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Herrenknecht’s boxhole boring machine (BBM) was developed for the excavation of vertical and inclined slot holes in underground mines

“Hoisting rock up a vertical mine shaft is by far the most costeffective method to get rock to the surface on a life-ofmine basis”

new products and projects Dumas is currently active at Agnico Eagle’s Pinos Altos project in Mexico. The top portion of the shaft, which is nearing completion, is a pilot-and-slash 4.9m-diameter concrete-lined shaft on a previously directionally drilled raise borehole. The second leg will be completed as a conventional blind sink

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UndergroUnd development 57 Shaft Sinkers is currently engaged in sinking or equipping eight shafts around the world

with the establishment of a twin-bin loadout arrangement for future permanent hoisting. Zuccherato comments: “Agnico Eagle has been a long-term client of ours and this is fourth shaft that Dumas has been contracted to excavate. Additionally, we are mid-way through completing another shaft-slash project in Peru for Minera Aurifera Retamas (MARSA).” In 2014, Dumas has already completed two other shaft projects in Canada. The first is a production shaft for North American Palladium at its Lac des Iles site near Thunder Bay, Ontario. It is a 6.1m-diameter concrete-lined shaft to a depth of approximately 825m. The second is a 6.7m-diameter production shaft that was sunk and commissioned for Hudbay Minerals at its Lalor project in Snow Lake, Manitoba. This shaft was part of a US$402 million mine-development project, and is designed to hoist at a rate of 6,000t/d. Wayne Mohns, VP operations, Canada at Dumas, says: “We see 2015 being an active year for shafts both in Canada and abroad.” Herrenknecht developed the shaft boring machine (SBM) with Rio Tinto to provide rapid construction of shafts with a high level of safety. It can create blind shafts with diameters of up to 12m in stable rock down to depths of 2,000m. In July, the company launched its new shaft-boring machine for shaft enlargement (SBE). The SBE works like a modern hard-rock TBM, but vertically. Benjamin Künstle, deputy division manager, mining at Herrenknecht, states: “The shaft-sinking time is reduced by 20% to 30% compared with conventional shaft-sinking technology.” Other advantages of the SBE include high precision in terms of verticality and the circular shape of the shaft cross-section, as well as virtually vibration-free ground treatment. The sinking cycle runs continuously and is not interrupted by drill-and-blast times or dispersal of explosion gases. Shaft diameters of up to 9.5m can be bored in hard rock for a wide range of applications. Künstle says: “The shaft depth is only limited by the technically feasible length of the pilot borehole.” Redpath has completed two shafts on the Oyu Tolgoi project in Mongolia’s Gobi

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“The latest trends in shaft sinking have focused on ‘doing more with less’ while providing a safer environment”

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Shaft Sinking Mine Development Contract Mining Raiseboring

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Raise Mining nderground Construction U Engineering & Technical Services Specialty Services

Dumas has a jointventure partnership for raise boring with Bergteamet

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UndergroUnd development

Tunnel boring Redpath is undertaking a hybrid TBM project in Queensland

Inclined drifts created using tunnel-boring machines (TBMs) can be used to replace vertical shafts to improve the accessibility of an underground mine. Martin Rauer, general manager of Robbins Asia Pacific, says: “In such a case, transport for men and material would not be restricted to a fixed number of shaft winches and hoists, which improves safety and logistical aspects.” Drifts into mines can be excavated at a very high advance rate compared with drill and blast, and the underground mine infrastructure can be developed a lot quicker when using TBMs, often accessing the ore or raw materials two to three times faster when compared with conventional mine-access methods.

new prodUcts and projects Herrenknecht has recently developed TBM solutions for the coal-mining industry, and the company sees potential growth in North America, Eastern Europe and Australia.

Redpath is undertaking a novel hybrid TBM project in Queensland, Australia, the first of its kind in Australian coal fields. The tunnel boring machine will mechanically excavate both the conveyor drift and the transport drift. Redpath’s South Africa team was involved in a first-of-its-kind sand tunnel worth US$6.1 million at Gem Diamonds’ Ghaghoo diamond mine in Botswana. Here, the company’s scope of involvement in the project included the development of a concrete-lined decline tunnel to 112m below the surface at an inclination of 8°, using a 50t open-faced tunnel shield (OFTS), which is 6m in diameter. Robbins has recently designed and built a TBM for a mixed-ground coal-mine drift. Rauer notes: “This hybrid hard-rock single-shield/earth pressure balance (EPB) TBM has successfully finished its first drift and will be launched very shortly to start the excavation of a second drift.” Another recent development was a machine for a gold and copper mine starting with a steep slope instead of using a shaft. This machine will be driven around an orebody spiralling down all the way to the bottom using a Robbins improved logistical concept. Concurrently with the excavation, different mining levels can be developed to start accessing the ore as fast as possible. The machine is planned to start operation soon.

Desert (one of which is the deepest shaft in Mongolia), and is sinking another two (one of 7m diameter and another 10m diameter and 1,200m deep) for the planned 85,000t/d operation. In Indonesia, Redpath has completed the Big Gossan production shaft (the country’s first shaft-hoisting facility), at the remote Freeport Grasberg operation in West Papua. In Canada, Redpath has completed shafts at Hudbay’s Lalor mine (Manitoba), at Goldcorp’s Cochenour mine (Ontario) and at Goldcorp’s Éléonore mine (Quebec). Sinking projects are taking place in Quebec and Saskatchewan. The projects in Saskatchewan, led by Redpath’s joint-venture company, include sinking three complex ground-freeze potash shafts at 1,000m depth. These potash projects are employing Redpath’s newest technologies for shaft mucking, and hoist controls and safety systems. Shaft Sinkers is engaged in sinking or equipping eight shafts around the world for major mining companies such as Randgold Resources, Vedanta, Lonmin, Impala Platinum, Royal Bafokeng Resources and Kazchrome. Davidov adds: “We are also involved in tenders for many shaft-sinking projects which are currently at various stages of development.”

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Physical seParation

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An FLSmidth Krebs hydrocyclone cluster

“Gravity separation… has not been fully developed and understood in terms of key parameters that determine its performance”

the fall and rise of gravity separation In an independent look at gravity classification and separation over the past 20 years, a researcher with Lappeenranta University in Finland suggests gravity is back where it belongs in the mineralprocessing R&D and application hierarchy – near the top. Richard Roberts reports

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icolus Rotich’s co-written “sustainability perspective” on gravity-based systems in mining is based on a review of the two decades book-ended by 1994 and 2014. It indicates that the pace of gravity classification and separation/concentration development, in the areas of application and research, has quickened again after becoming somewhat sluggish in the last quarter of the 20th century. Environmental factors are playing a pivotal role in this revival, in mining and other industries, he says. “Maximum recovery at minimum cost, coupled with high efficiencies, effectiveness and environmentally acceptable operating standards, are the main objectives during modern plant setup,” says Rotich and his co-authors Ritva Tuunila and Marjatta Louhi-Kultanen from the Lappeenranta University of Technology (LUT) Department of Chemical Technology. “Sustainability is a new entrant to the competitiveness of industries. Many companies have had to re-think the use of gravity due to the high costs of flotation reagents, the relative simplicity of gravity separation, the fact that it creates less environmental pollution, and

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Physical seParation

efficiency, even for particulates at the range of 50μm. “Gravity concentration is as good as a renewable source of energy, converting potential energy to mechanical agitation in size separation. Gravity separation enables the optimisation of plant energy in cases where it is used as a means of pre-concentration before subjecting the material to electrically powered processes. In remote places, gravity is also used in concentration where external energies are out of reach,” continues Rotich. “The low cost and environmentally friendly operation has led to the intense use of gravity for the recovery of gold. Moreover, we expect that limitations of discharge will be tightened by legislation in the future, further favouring gravity-separation processes over other methods.” Rotich says there is a “clear role [for] gravity separation in the present-day mining industry”. “[Despite] all misconceptions [about] the downfall of gravity separation, these methods have grown to see the light of day after all. Industrialists have realised that some processes such as concentration of some unique metal-bearing ores – for example, cassiterite, chromite, wolframite and tantalum, among others – use gravity as the only mode of concentration. [And] beneficiation of gold has long been accomplished with gravity-based separators such as spiral concentrators. “In general, orebodies requiring thorough treatment are becoming increasingly complex,” Rotich says. “In China, for instance, most

vanadium is discovered from vanadiumtitanium magnetite ore and stone coal, making its extraction expensive in terms

of large ore-tonnage mix, expended energy, chemical (acid) consumption and total costs. Traditional processes for the extraction of vanadium from ore may involve methods such as direct acid leaching, roasting-acid leaching, calcified roasting carbonate leaching, low salt roasting-cyclic oxidation and roastingalkali leaching. In such cases, decarburisation, followed by selective grinding before pre-concentration with gravity, makes it easier to reject about 28.9% of the feed ore before the main extraction.

61

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Physical seParation

Copper recovery on a Wilfley 7000 water table; a GIW hydrocyclone

“Even today, most giant mineral-processing companies in Australia, South Africa, China, Chile, Russia and Peru still value gravity as one of the most competitive methods for concentrating minerals,” Rotich adds. “A multinational corporation in the mining sector reported [this year] that replacement of differential flotation with gravity separation in its operation enhanced concentration in a tin-recovery plant by 8-10%.”

“Giant the role of research Moi University, Kenya, graduate in mineral- A2007 (bachelor of technology), Rotich processing worked in a government industrialcompanies research institute for three years before moving to Lappeenranta University to in Australia, attain a master of technology degree in South Africa, environmental engineering. After that, he started on his doctor of China, Chile, securing science in chemical engineering degree Russia and last year, majoring in physical separation Peru still of solid particles. “Physical separation is an old process, value gravity not only in mining but also in the energy as one of sub-sectors – for example, beneficiation coal,” Rotich says. “More important the most of are the recently developed sustainable competitive biomass processing and refining systems methods for [such as] the new combustion systems for generating steam, especially in concen- Scandinavia, which require sizing of trating solids, be they domestic animal wastes solid residues from forests. These minerals” or were some of the fundamental reasons that drove me to investigate these processes. “The mechanisms of solids separation, in particular, have a history of being poorly understood in academia [with more than 20 journal papers citing this], so this was one important aspect that will make the dissertation not only technological but also academic.”

Rotich will present a paper based on his extensive investigation of modelling, experimental verifications and re-engineering of particle-classification systems, at a major international mineral-processing congress in mid-October in Santiago, Chile. The paper is focused on the optimisation of gravity-separation deck angles and feed throughput. “We [previously] developed mathematical schemes for quantifying the rates and efficiencies for solid separation, and we are continuing the work now with empirical studies aiming to verify those models,” he says. Rotich explains that LUT, established in 1969, was among a handful of Finnish universities that gained international standing for practical R&D aimed at providing industry with real technical solutions. “Nowadays, LUT’s strategic focus areas are green energy and technology, the creation of sustainable competitiveness and operation as a hub of international Russian relations,” Rotich says. The government collaborates with the universities to set priority areas that are geared towards benefiting the industry and society in general. The universities in turn implement strategic plans with the sole purpose of benefiting the environments around them. And they tend to be specialised, so that each university is known for a specific discipline strength.

boosting gravity seParation Rotich says that the fundamental aim of gravity classification is to separate material into definite regimes of behaviour class patterns. It generally promotes high operational efficiency in equipment, could improve material handling within process units, and

ensures that the best-quality product goes to downstream processes (including final use). In mining, gravity separation helps to curb tendencies of over-grinding and high energy consumption. Key mineral-processing gravity systems have undergone several metamorphic re-designs in recent times in order to fit to the current industry permutations, notes Rotich. Yet not so long ago, gravity separation “became a neglected subject in academia, technical conferences and research in journal papers. It ended up being given a cold shoulder in most scientific forums, [with] gravity separation papers labelled among ‘others’ and always banished to the last afternoon [of conferences]”, he says. It was thought that young mineralprocessing engineers would not be willing to specialise in gravity concentra-

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Physical seParation

tion. “These misconceptions almost led to a collapse in the continual development in theory and its practical applications,” Rotich says. “Gravity separation, old as it is, has not been fully developed and understood in terms of key parameters that determine its performance. The subject has been deficient, especially when it comes to the use of modern tools such as mathematical modelling and simulation, statistical and computational techniques which have allowed other fields to prosper stunningly in the last few years. “Attention seems to have shifted [in this period], leading to a sharp increase in the number of publications in the area of gravity separation, with significant advances including the mathematical modelling and simulation aspect. Some researchers report new discoveries on methods/configurations of gravity separators that have resulted in the successful extraction of particles smaller than 0.5mm.” But Rotich says there remains a real need for more accurate methods of quantification and optimisation of the operating parameters of gravity separators. He believes that increased interest in gravity separation is being driven partly by a deeper focus in the industry on more environmentally responsible solutions in response to increasingly weighty social, energy, water and cost challenges. “The industry has to work within certain constraints, imposed not only by economies of scale, but also by adherence to factors of sustainability, such as the corporate, social and environmental responsibility concept among others,” Rotich says. “Cost and maximum recovery are no longer the only dicta in plant design. On the contrary, today’s optimum plant design is determined by a cocktail of complex criteria composed of efficiency, effectiveness and environmental sustainability, together with the fact that maximum product recovery may not necessarily conform to optimal industry economics. “In fact, most studies have pointed out with evidence the contrasting and/or competing relationships between separation capacities or rates, and corresponding efficiencies even within the unit operations themselves,” he adds. Rotich says that while selecting optimal operating parameters for gravity systems could be extremely difficult and tedious, it might soon be a thing of the

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65

past with the advent of the fast computers and computational algorithms currently available. “It is now possible to vividly model these dynamics within a shorter time,” he comments. In the past few years, researchers have attempted to come up with various computational models that could soon allow optimisation, and possible improvement both in performance and understanding. “[But] the bitter truth about computer models is that correctness in the mathematical description of the systems is crucial to modelling. Incomplete information will definitely cause mis-description to the model, and consequently poor performance,” concludes Rotich.

Weighing up the options Gravity separation played an important role in the pre- and post-industrial revolution era, and prior to the development of advanced gravity separation, hand picking was used for well over 2,000 years. In fact, sources refer to separation by density difference as being as old as recorded history. Yan and Gupta date it back to 3,000BC as recorded in writings from ancient Egypt (Yan & Gupta, 2006). Thinking the industrial revolution to have been a spontaneous phenomenon might suggest that the adoption of gravity separation was simultaneous and widespread throughout the world. However, chronological records show a slowdown in development of gravity separation after the first half of the last century, due to partial replacement by novel methods such as flotation, magnetic separation and leaching (Richards & Palmer, 1997). Despite the advance of these replacement technologies, gravity separation has not only survived over the years but also thrived, kept pace with, and grown with what is now a competitive industry. Issues such as the extra cost of grinding particles to flotation sizes and the addition of reagents, as well as environmental concerns about alternatives, have contributed to a resurgence in interest and development for gravity separation. There are a Nicolus Rotich

number of other obvious reasons for a reluctance to move away from gravity-separation techniques, including the fact that it is generally highly energy-efficient as it uses the natural force of gravity; it is environmentally friendly (no fuels involved, no firing/heating); it can offer quite high separation efficiencies and low cost (e.g. cone and spiral separators), and can handle high capacities of solids up to 272t/h. Gravity systems can also be quite simple to implement and are based on proven methodologies. They offer numerous and flexible geometry configurations, all with different benefits, many of which have not been properly explored. On the flipside, gravity separation has not been fully understood in terms of key parameters that determine its performance, such as the motion of particles on different surfaces. Dust control in dry processes can also be challenging, and efficiency and effectiveness in fine particle separation are still questioned (significant losses can occur in rare-earth separation, for example). There have also been concerns that some new mineral deposits present new challenges, including those hindering the use of gravity as a sole means of concentration. Examples of this group include orebodies bearing rare-earth elements such as bastnäsite, monazite and xenotime, which require the combined efforts of concentration methods, usually froth flotation and magnetic separation, in addition to gravity concentration. Nicolus Rotich

Lappeenranta University of Technology in Finland is carrying out timely research into gravity separation

“Some researchers report new discoveries on gravity separators that have resulted in the successful extraction of particles smaller than 0.5mm”

October 2014 12/09/2014 08:31


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Water management

Learning from manufacturing Other industries are a great place to learn more about water use efficiency, Resa Furey of MWH explains

Establishing a culture of dry floors has led to dramatic reductions in water use in many industries

H

ow water is used and whether it is used efficiently are of strategic importance in mining. Rapidly depleting aquifers, communities set on protecting water sources, and increasingly strict regulations and effluent standards present risks to be managed if production targets, returns and stakeholder relationships are to be maintained. Industries including oil and gas, and manufacturing go to great lengths to understand the risks and costs associated with their water and they share ambitious goals with the mining industry to reduce water use. Following are some lessons that can be learnt.

Measure aND aNaLYse

“Leveraging the best practices from other industries can inform our approaches to reducing, reusing, recycling and replenishing water resources”

Measuring and monitoring provides information so that operators can make good decisions. Manufacturers generally buy water from, and discharge wastewater to, municipalities. They are charged for water in and out, and the quality is closely monitored. As a result, manufacturers generally go to great lengths to collect water flow and quality data, which is then measured, and carefully managed. This data helps to fine-tune the metrics on water use and accomplish goals. At manufacturing plants, data collection is facilitated by the fact that flows are often smaller than those commonly found at mines, and the process is closed, whereas mines are exposed to various factors (precipitation, evaporation and other environmental variables) that complicate the water balance. In addition to passive data collection, conducting water audits that define the sources, uses, volumes and quality requirements help identify the ‘thirsty’ areas of plant or mine. Water audits can identify inexpensive fixes that can be prioritised and implemented quickly, as well as longer-term projects. In contrast, most mines use ground and surface water, and often consider it to be ‘free of charge’. Yet the true cost of water includes costs for permitting, well installation, investigations, pipelines, pumping, maintenance, treatment and disposal of water, as well as the impact that water quality has on extraction efficiency. These costs make effective use of the water worth measuring. The water balance in any operation and the chemical mass balance of those water streams is an extremely important source of information. Every mine and

manufacturing plant needs a full understanding of the water balance (water inputs versus outputs) and what is in the water. Imagine the water balance for a food and beverage company where water is one of the main ingredients in the product: if water withdrawal is limited, too much residual use could stop production. A water balanced operation means taking an ‘only what you need’ approach to water, because you know how much you need. Knowing what is in the water and understanding which streams can be reused with minimal treatment can improve the water equation and shift the balance in your favour.

set goaLs With this information, operators can set water reduction goals. An example of one such goal is: “By 2020, safely return to communities and nature an amount of water equal to what we use in our finished beverages and their production.” Achieving goals like this means going beyond conservation to embrace projects with at least one of four objectives: • Improve access to water and sanitation; • Protect watersheds; • Provide water for productive use; and/ or, • Educate and raise awareness about water issues, including engagement on water policy.

act In every industry, conservation is often the first goal and the beginning to mitigating water-supply risks. There is a reason why reduce, reuse, recycle is said in this order – because conserving water is the easiest and least expensive of the three. Reusing and recycling water are two other effective ways to conserve. Water recycling takes place when water is sent back or used again within the same process, regeneration (aka treatment) may occur prior to recycling. Water reuse takes place when water is taken from one process and used in another – regeneration may occur before the water is recycled. Adding infrastructure such as pipes and treatment circuits to enable reuse and recycling can be costly, which is why most companies look for opportunities to conserve water. All reuse and recycling circuits must

consider the quality and chemistry of the incoming water and compare those metrics to the water stream that is needed. Opportunities for water reuse and recycling are best considered at the plant design stage since retrofitting an existing operation to accommodate reuse or recycling can be even more expensive. It should be noted that miners are – in many cases – far ahead of the manufacturing industry when it comes to water reuse and recycling, it is not uncommon for up to 90% of the water used in mineral processing to be reused. One poignant conservation lesson that can be learned from manufacturers comes from the idea of establishing a culture of dry floors. This has led to dramatic reductions in water use in many industries, and with some effort can also be adopted in mining. Sharing production metrics and costs with employees is done routinely across most manufacturing industries. Some sites go so far as to also communicate the water costs and volume used. Including these numbers on the daily production board communicates the importance of water and can be a significant motivator in driving water conservation. Sharing this information helps set realistic goals and allows operations to be held accountable towards reaching their goals. Adding an element of fun or “gamification” such as turning water-use reduction goals into a contest is one tactic used in other industries. When posted in a conspicuous place (such as the employee lunch room), this daily reminder reinforces which goals are important and how well the company is doing at achieving them. Finally, another lesson other industries provide is the idea of making treatment part of the business – while not directly transferable to all miners, some large chemical manufacturers, for example, also play in the water treatment industry, ie treatment is part of their business. While treatment may be a necessary cost of operation for a mining company, leaving behind a legacy of clean water can only be beneficial. Leveraging the best practices from other industries can inform our approaches to reducing, reusing, recycling and replenishing water resources. What is precious must be used wisely.

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water management

Cheaper selenium removal David Kratochvil explains how innovation in water treatment can generate major savings for the cost of compliance with new selenium regulations Two views of the BioteQ Selen-IX pilot plant

Fig 1: schematic of the Selen-IX process

E

ssential to all life in trace amounts, selenium at higher concentrations has been found to have implications for humans, animals and aquatic life. This rising awareness has led to new selenium regulations being promulgated and enforced by regulatory agencies in the US and Canada, as indicated in Table 1. As a result, the mining industry is in need of innovative and effective methods to reduce the cost of removing selenium from mine-impacted waters. Selenium is a naturally occurring element that acts as a substitute for sulphur in a variety of minerals present in coal, base metal and precious-metal ore deposits. Consequently, trace concentrations of selenium can be present in waters generated by a wide spectrum of mining, mineral processing and hydrometallurgical operations. One of the most challenging streams to treat is run-off water that comes into contact with waste rock and/or exposed mineral surfaces in open pits and underground workings in wet and cold climates, where the volume of wastewater is very high (often in the order of tens of thousands of cubic metres per day), the water temperature is low, and the selenium concentration is highly variable, typically in the range of 10-1,000ppb. Although different selenium species can be present, the large majority of selenium in mine-impacted waters is hexavalent selenium or selenate. Currently, the only systems commercially available to treat high flows of mine water containing selenate include membranes combined with evaporators-crystallisers, and/or biological selenium-reduction systems. The main disadvantages of these systems are the high capital and operating costs. These can translate into significant water-treatment life-cycle costs that can run hundreds of millions of dollars per wastewater stream. Although

the industry has applied these systems at several sites in the US and Canada, the large majority of sites where active treatment for selenium removal is needed remains uncommitted, primarily due to the high life-cycle costs. This has created a gap in the market for innovators who may be able to develop a new treatment system that would help the mining industry achieve compliance with selenium regulations cost-effectively.

Selen-IX BioteQ is one company working to bring a cost-effective solution to market within the next 12 to 24 months. BioteQ’s new patented selenium-removal process, Selen-IX, is based on selective ion exchange (IX) combined with electrochemical reduction of selenate to selenium metal. The ion-exchange part of the process allows the treatment of large volumes of cold water, regardless of the feed selenium concentration, down to as low as 1ppb, using commercially available ion-exchange resins placed in a set of columns arranged in a compact module. The ion-exchange process is selective for

selenium, leaving other non-toxic constituents such as chloride and sulphate in the water, which reduces treatment costs. While the majority of columns in the module receive selenium-laden wastewater, several columns are always being regenerated, which ensures that freshly regenerated resin is always available for continuous treatment. The volume of the spent regenerant brine solution is only a fraction of the volume of water treated. Consequently, this small volume of spent regenerant solution contains selenium at concentrations several orders of magnitude greater than in the feed, e.g. 5,000 to 30,000ppb, and is directed to an electrochemical selenium-reduction step where iron is added to the brine solution and selenium is removed in the form of an iron-selenium solid. The selenium solids are separated from the solution and subsequently dewatered. With the brine solution free of selenium solids, it is then recycled back to the selenium IX step. Recycling of the ion-exchange regenerant eliminates waste liquid brine that is typically produced by conventional IX systems and reduces the overall operating cost of the treatment process. The only by-product of the Selen-IX process is a small quantity of stable inorganic iron-selenium solids that passes the US Environmental Protection Agency’s Toxicity Characteristic Leaching Procedure (TCLP) tests as non-toxic, and that can potentially be shipped to steel-alloying operations that represent one of the main consumers of selenium metal.

PIlot Plant Based on successful laboratory bench-scale testing, BioteQ constructed a mobile Selen-IX pilot plant that allows the company to offer field testing of its new process on waters collected

Table 1: selenium discharge requirements Jurisdiction & requirement

Discharge Limit (ppb)

Canada – Aquatic Life WQG

1-2

Canada – Drinking Water

10

US EPA – Aquatic Life WQG

5

US EPA – Drinking Water

50

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water management

directly at customer sites. The pilot plant can operate under any weather condition, on a continuous basis, and is fully automated for ease of operation. In the latter part of 2013, BioteQ deployed the Selen-IX mobile pilot plant to test selenium removal from mine-impacted surface water for a Canadian mining company. With anticipated regulatory changes to permissible selenium discharge levels, the pilot trial was undertaken to test the effectiveness of Selen-IX to remove selenium to a requisite limit of < 20ppb and a desired elective limit of < 5ppb. Feed water composition for the pilot is summarised in Table 2. Figure 2 shows the selenium concentration in 24-hour composite samples of the plant feed and discharge during the 24/7 continuous operation of the pilot. The data points represent consecutive days of operation and demonstrate that the pilot plant was able to produce treated effluent that met the requisite limit of < 20ppb. Once plant operations were optimised after a few days, the desired elective limit of < 5ppb was also met.

The pace at which Selen-IX has moved from bench scale to pilot scale along with the positive results from pilot testing obtained to date indicate that the technology will be commercially ready in the next 12 to 24 months More importantly, the results of pilot testing indicate that Selen-IX can, depending on feed flow and composition, deliver significant savings of 30-80% in the lifecycle cost of selenium removal in comparison with other commercially ready technologies. These savings will come from minimising solids handling and disposal, reducing plant footprint and replacing large site-erected tanks and structures with a pre-fabricated modular system, and no requirement to pre-heat the cold feed water to ensure proper operation of the system. Selen-IX also eliminates the need to polish and remove residual phosphate and biological oxygen demand that results from biological treatment methods. In addition, it minimises the pre-treatment requirements of membrane systems, which are susceptible to a host of constituents

commonly found in mine waters, including finely suspended solids and chemical constituents such as aluminium, iron, silica, manganese, alkaline earth metals and sulphate.

69

Fig 2: pilot feed and discharge during pilot operation

Table 2: pilot feed composition Constituent

Feed

Selenium

457ppb

Chloride

27ppm

Nitrate

57ppm

Sulphate Alkalinity Total dissolved solids

2,050ppm 436ppm 2,983ppm

David Kratochvil is president and interim CEO at BioteQ Environmental Technologies. See: www.bioteq.ca

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A selection of articles from Mining Magazine 100 years ago…

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Advertisement offices Head office Contact: Richard Dolan Aspermont Media, 120 Old Broad Street, London EC2N 1AR, UK T +44 (0)20 7216 6060 F +44 (0)20 7216 6050 E richard.dolan@aspermontmedia.com Germany & Austria Contact: Gunter Schneider GSM International, Postfach 20 21 06, D-41552 Kaast, Germany. T +49 2131 511801 E info@gsm-international.eu Asia, Australia, Europe, South Africa, South America plus Canada, Ireland, UK & US Contact: Tom Peck Aspermont Media, 120 Old Broad Street, London EC2N 1AR, UK T +44 (0)20 7216 6085 F +44 (0)20 7216 6050 E tom.peck@aspermontmedia.com North America, Australia Contact: Chad Dorn 8727 E. 35th Avenue, Denver, CO 80238, US T +1 720 855 3996 E cdorn@miningadvertising.com

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Annual subscription – UK and Europe £95.00 (160.00 euros) Rest of the world US$170.00. Additional current copies are available to subscribers at £12 (US$21) each Mining Magazine USPS 005-829 is published 10 times each year with combined issues in Jan / Feb and Jul / Aug – by Aspermont Media, 120 Old Broad Street, London EC2N 1AR, UK. Printed by Stephens & George Magazines, Merthyr Tydfil, UK The 2014 US annual subscription price is US$170. Airfreight and mailing in the US by Agent named Air Business, c/o Worldnet Shipping USA Inc, 149-35 177th Street, Jamaica, New York NY11434 Periodicals postage paid at Jamaica NY 11431 US Postmaster: send address changes to Mining Magazine, Air Business Ltd, c/o Worldnet Shipping USA Inc, 149-35 177th Street, Jamaica, New York NY11434 Subscription records are maintained at Aspermont Media Ltd, Chancery Exchange, 10 Furnival Street, London EC4A 1YH, United Kingdom Aspermont Media, publisher and owner of Mining Magazine (‘the publisher’) and each of its directors, officers, employees, advisers and agents and related entities do not make any warranty whatsoever as to the accuracy or reliability of any information, estimates, opinions, conclusions or recommendations contained in this publication and, to the maximum extent permitted by law, the publisher disclaims all liability and responsibility for any direct or indirect loss or damage which may be suffered by any person or entity through relying on anything contained in, or omitted from, this publication whether as a result of negligence on the part of the publisher or not. Reliance should not be placed on the contents of this magazine in making a commercial or other decision and all persons are advised to seek independent professional advice in this regard.

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