Inside MIning October 2014

www.miningne.ws

IN THE

SPOTLIGHT

AFRIC AN UPDATES ON THE

GROUND AND UNDERGROUND

Dr Anthony Hodge: Biodiversity in Mining

COMMODITY DIAMONDS

Discovering Kimberlite

JUNIOR MINING Burkino Faso’s Gold Boom

DRILLING & BLASTING

Megalodon Rock Breaker

JOHNSON CRANE HIRE

Brains, and Brawn, Won the Day

MINERALS PROCESSING

Increasing Productivity

ISSN 1999-8872 • R50.00 (incl. VAT) • Vol. 7 • No. 10 • October 2014

CONTENTS

A F R I C A N U P D AT E S O N T H E

ining

October 2014

GROUND AND UNDERGROUND

ENDORSED BY

EDITOR’S COMMENT ON THE COVER O

www.miningne.ws

IN THE

SPOTLIGHT

AFRIC AN UPDATES ON THE

GROUND AND UNDERGROUND

Dr Anthony Hodge: Biodiversity in Mining

COMMODITY DIAMONDS

Discovering Kimberlite

P8

3 Exciting times

B Brains, and brawn, won the day TThe ability to successfully develop and d deliver a specialised lifting solution was d demonstrated in the heavy-lift operation u undertaken by Johnson Crane Hire at S Sasol’s Secunda plant recently. And, it w was by no means a small feat.

IN THE SPOTLIGHT

4 Biodiversity in mining AFRICA ROUND-UP

6 Mining news from the continent

JUNIOR MINING Burkino Faso’s Gold Boom

DRILLING & BLASTING

Megalodon Rock Breaker

COVER STORY

JOHNSON CRANE HIRE

Brains, and Brawn, Won the Day

8 Brains, and brawn, won the day

MINERALS PROCESSING

Increasing Productivity

ISSN 1999-8872 • R50.00 (incl. VAT) • Vol. 7 • No. 10 • October 2014

DIAMONDS

10 Airborne gravity gradiometry systems 12 To mine or not to mine 14 Diamond laboratory, a first for Africa 18 Diamonds on the soles of

its feet

20 Steadily towards the future 23 Building a leading diamond exploration company 18

MINERALS PROCESSING

26 A change for the better 29 Mopani Copper installs two BMR winders 32 A systems approach to transfer point design 34 Screening terminology 35 Old but still effective JUNIOR MINING

37 Bukino Faso’s gold boom DRILLING & BLASTING

40 Undersea Mining 41 Licence to drill 42 New rock drill a leap ahead 44 Fractum, a megalodon rock breaker 45

MINE SAFETY

45 3D laser technology 47 Training for safer mines 49 Thwarting Danger TECHNOLOGY

51 Lighting up Hotazel 53 Abrasion resistance 54 Venitia creates an intelligent 3D model MINING SERVICES

55 Remote mining camp management 55

56 A new centre of

excellence

IN SID E M IN IN G 1 0 | 2014

1

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Continuously committed. Redefining the industry.

EDITOR'S COMMENT

Publisher Elizabeth Shorten Editor Tony Stone Online editor Sylvester Haskins Head of design Frédérick Danton Senior designer Hayley Mendelow

Exciting times

Designer Kirsty Galloway Chief sub-editor Tristan Snijders Sub-editor Beatrix Knopjes Production manager Antois-Leigh Botma Production coordinator Jacqueline Modise Marketing manager Hestelle Robinson Digital manager Esther Louw Financial manager Andrew Lobban Administration Tonya Hebenton Distribution manager Nomsa Masina

Besides celebrating Heritage Day on 24 September and enjoying “braaivleis, sonskyn and Chevrolet”, for those who remember what this was, the month of September, as far as mining conferences and exhibitions were concerned, was an exciting time – at least for ‘diehards’ of mining.

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F

IRST UP WAS THE successful fourday Kimberley Diamond Symposium and Exhibition organised by the Geological Society of South Africa, in conjunction with John Bristow and Mike De Wit. It was very well attended, with delegates from as far afield as Canada, the USA and Russia enjoying Northern Cape hospitality. A well-thought-out agenda, with an array of interesting presentations and mine visits, had diamond mine owners, geologists, metallurgists and OEMs thoroughly entertained – even with the one or two intellectually challenging papers.

I joined a group of geologists and a brave metallurgist, led by Jock Robey, who explored an old De Beers tailings dump that was being re-mined by Super Stone Mining (no relation).

Like the geologists, I feverishly hunted for kimberlite hoping to find a diamond. Zdislav Spetaius, a geologist from Russia, and Martina Bezzola, a geologist from Canada, were among the group of grown-up kids on the treasure hunt. Needless to say, with a yield of 14 carats per 100 tonnes, no one found a diamond, or at least did not let on that they had. Included in this edition are a few of the papers and posters presented at the symposium. We acknowledge Martina Bezzola (left) and Zdislav Spetaius (right) feverishly hunting for kimberlite

To our avid readers, be sure to sign up and get the latest updates and inside scoops from the mining industry.

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all the authors for the fine work they did, are doing, and for their contributions.

Next up was the much-anticipated Electra Mining week at NASREC. This year must have been a bumper year. Taking up all the halls and outdoor exhibition space, plus a couple of gigantic marquees, everyone who is someone and has something to do with mining was there. At least this time I did not see MIBs sneaking around photographing every detail of the technology items they wished to replicate. In terms of technology, products and services, there was more to digest than ever before. It simply was not possible to breeze in and breeze out in a single day. After three days, I managed two halls, the marquees and the outdoor area. I chatted in some detail to 108 exhibitors and interviewed 11 people, and that was me. I was done. Even so, the one thing that struck me most was the ingenuity of humanity. Every piece of technology on display, from hard hats to drilling machines, was invented, enhanced and developed to solve problems and meets specific needs. We discover this when we take the time to talk to people, ask questions and consider the solutions in the context of our own mining interests. With exhibitions like this, one does not need DSTV because we have our own live reality show. I must be a diehard.

Going forward, we have the 6th International Platinum Conference at Sun City between 20 and 24 October, which should be interesting as this takes us to the ‘coal face’, as it were. With some Amplats mines up for sale and mine mechanisation sure to be on the agenda, the conference will no doubt illicit a huge amount of interest.

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IN SID E M IN IN G 1 0 | 2014

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IN THE SPOTLIGHT

Biodiversity in mining We are our world. What we do with our world will shape our future. Inside Mining supports the International Council on Mining & Metals in its efforts to ensure biodiversity in mining. We urge you to do so as well. By Dr Anthony Hodge

B

IODIVERSITY encompasses the variety and variability of life on Earth. It refers to the differences within and between all living organisms at their different levels of biological organisation – genes, individuals, species and ecosystems.

Biodiversity embraces all living organisms and their genetic diversity, a vast and complex array of ecosystems and habitats, as well as the processes that underpin and result from this diversity, such as photosynthesis, nutrient cycling or pollination.

Different species – plant, animal, fungal and microbial – interact with each other in a variety of ecological processes to form ecosystems. These processes are in turn the result of the interactions between species and with their physical and chemical environments.

The combination of a diversity of life forms and their interactions with each other, and with the rest of the environment, has made Earth a uniquely habitable place for humans. Biodiversity sustains human livelihoods and life itself.

The interdependence between people and biodiversity is most apparent for some indigenous peoples, who may lead a subsistence lifestyle and be critically dependent on biodiversity, or whose culture and history are intimately associated with the natural environment and systems.

In many Western cultures, although our dependence on biodiversity has becomes less tangible and apparent, it remains critically important.

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Relevance to mining operations Mining has the potential to affect biodiversity throughout the life cycle of a project, both directly and indirectly. Direct or primary impacts from mining can result from any activity that involves land clearance (such as access road construction, exploration drilling, overburden stripping or tailings impoundment construction) or direct discharges to water bodies (riverine tailings disposal, for instance, or tailings impoundment releases) or the air (such as dusts or smelter emissions). Direct impacts are usually readily identifiable. Indirect or secondary impacts can result from social or environmental changes induced by mining operations and are often harder to identify immediately. Cumulative impacts occur where mining projects are developed in environments that are influenced by other projects, both mining and non-mining.

The potential for significant impacts is greater when mining occurs in remote, environmentally or socially sensitive areas.

Due to the continuing demand for minerals, the depletion of resources in readily accessible areas and changing technologies and economics in the mining sector, mining is increasingly being proposed in remote and biodiversity-rich ecosystems that were previously unexplored and undeveloped for minerals. This has also been made possible by the implementation of mining sector fiscal and regulatory reforms to encourage foreign direct investment in many developing countries.

This trend in opening up new prospective areas to mineral resources development

provides an opportunity for the mining industry to demonstrate that practices and decisions have improved. It can also represent a threat, however, and poor performance could limit access to some highly prospective areas.

Despite the significant potential for negative impacts on biodiversity from mining operations, there is a great deal that companies can do to minimise or prevent such impacts in areas identified as being appropriate for mining. There are also many opportunities for companies to enhance biodiversity conservation within their areas of operations. Being proactive in the assessment and management of biodiversity is important not only for new operations but also for those that have been operating for many years, usually under regulatory requirements that were less focused on the protection and enhancement of biodiversity. It is also important to recognise that not all mining takes place in remote or highly sensitive areas. Some greenfield or expansion projects will be developed in relatively highly populated areas, industrial settings or regions that have been intensively farmed for many decades, where biodiversity is of limited value. This will

IN THE SPOTLIGHT

Flyfishers are generally concerned about the environment. Clubs, associations and working groups have been formed and have taken on various conservation projects countrywide. They work to protect critical habitat, to reconnect degraded waterways and to protect vast wetlands that supports a diverse array of life, not only trout. Examples include the Emfulenis sewage works and the acid mine drainage into the Tweeloopies Spruit as well as pollution of the Vaal river from the Barrage to Parys

become apparent after a modest investment of effort to establish the biodiversity context of a proposed project. In such situations, the focus should be on developing a sufficient understanding of local biodiversity and exploring opportunities for biodiversity enhancement or creative conservation with appropriate partners.

Why mining companies should consider biodiversity Setting aside any ethical or moral considerations, which are increasingly the subject of corporate policies, it is important for companies to address biodiversity for a variety of sound business reasons.

Many mining companies have adopted

an increasingly sophisticated approach to managing biodiversity as part of their commitments to establishing and maintaining a social or functional ‘licence to operate’. For example, adopting responsible practices with respect to biodiversity management is increasingly viewed as important with respect to: • access to land, both at the initial stages of project development and for ongoing exploration to extend the lifetime of existing projects • reputation, which links to ‘licence to operate’, an intangible but significant benefit to business, and which can profoundly influence the perceptions of communities, NGOs and other stakeholders of existing or proposed mining operations • access to capital, particularly where project finance is to be obtained from one of the investment banks that are signatories to the Equator Principles’ Principle 2, which applies the Biodiversity Performance Standard 3 of the International Finance Corporation to all investments in excess of $10 million (recognising that strengthened commitments to biodiversity assessment and management are likely to be adopted).

In each issue, Inside Mining offers advertisers the opportunity to promote their company’s products and services to the appropriate audience by booking the prime position of the front cover which includes a two-page feature article. The magazine offers advertisers an ideal platform to ensure the maximum exposure of their brand. Please call +27(0)11 465 5452 to secure your booking.

In addition, good biodiversity management can bring benefits to mining companies, including: • increased investor confidence and loyalty • shorter and less contentious permitting cycles, as a result of better relationships with regulatory agencies • improved community relations • strong supportive partnerships with NGOs • improved employee motivation • reduced risks and liabilities.

There is no question that mining companies need to improve biodiversity management throughout the mine life cycle.

Mines should minimise the likelihood of negative impacts on biodiversity, project delays and damage to their reputations.

When setting rehabilitation objectives for biodiversity, mining companies should always take into account the management requirements needed to sustain conservation values in the long term, responsibilities for implementation and how the costs of management will be funded.

Note: Please visit http://www.icmm.com/document/13 to download the publication ‘Good Practice Guidance for Mining and Biodiversity’

IN SID E M IN IN G 1 0 | 2014

5

AFRICA ROUND-UP

MINING NEWS

from around the conƟnent

in associaƟon with KENYA Africa has an untapped crude oil resource of 130 billion barrels waiting to be recovered by more than 500 companies, according to a recent report by PricewaterhouseCoopers. Much of this resource lies in Kenya, where commercial oil production is expected to begin in 2016 and discovery after discovery has made this the hottest and fastest-paced hydrocarbon scene on the continent. The British explorer behind Kenya’s oil discovery debut in 2012, Tullow Oil, last month announced another oil find that will extend the already proven South Lokichar basin ‘significantly northwards’. In May, Tullow and partner Africa Oil Corporation announced the country’s first commercial oil discovery, worth $10 billion, in the Lokichar basin. The next testing ground will be the neighbouring Kerio basin, which should get off the ground later this month, while there has been a flurry of attention lately surrounding the Ogaden basin where initial estimates are enough to send stocks soaring. Investors will now be looking at who is poised to make the next discovery.

BOTSWANA London-based miner Gem Diamonds in September announced the opening of the Ghaghoo diamond mine in Botswana, which will be the first underground diamond mine in the country. The company operates the Letšeng

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INS I DE MI NI NG 1 0 | 2 0 1 4

mine in Lesotho, with the Ghaghoo set to be Gem’s second major producing mine.

Gem sees the opening of Ghaghoo mine as a significant milestone for the company and marks the event with a ceremony to be attended by the president of Botswana, Ian Khama. The Ghaghoo diamond mine will be the first underground diamond mine in Botswana – home of the world’s leading diamond producer. Through a phased development plan, Ghaghoo will be among a new generation of diamond mines in Botswana, stated Gem. Gem undertook a series of extensive studies and assessments relating to the environment, local communities and broader social impacts of the Ghaghoo mine. This is a strategic priority for the company in a rapidly changing environment for the global mining industry, and will contribute to the modernisation of the diamond mining industry to ensure long-term sustainability, said Gem in a statement.

Listed Australian miner Discovery Metals placed the development of its Zeta underground mine in Botswana on hold, it announced in September. The miner said that a proposed AU$25.7 million rights issue, which was announced at the start of September this year, would not proceed, after the company’s lenders claimed a breach. The copper miner announced that it provided lenders with an updated development plan and financial model for review as required by the business plan condition.

ZIMBABWE Diamond mining company Alrosa is forming a partnership in a Zimbabwe-Russia joint venture company that will prospect for diamonds in the Southern African country, Russia’s Trade and Industry Minister, Denis Manturov, said on 15 September.

Russia’s major investment in Zimbabwe is a joint-venture diamond and gold mining company in eastern Zimbabwe – DTZ-OZGEO. The Eastern European nation is also planning a joint platinum mining operation outside Zimbabwe’s capital, Harare.

Diamonds are mined in the south of the country by private company River Ranch, in central Zimbabwe by Rio Tinto and in the eastern Marange area, which caused controversy when 20 000 illegal miners were evicted by soldiers and police in 2008, according to a Reuters report.

The Russian firm also wants to help Zimbabwe with sorting and evaluating its diamonds. “I would like to point out that Alrosa has come up with a proposal to the Zimbabwean side to extend expert assistance to Zimbabwe in the field of organising the system of sorting, valuation and marketing of its diamonds,” Manturov said. Russia is now the target of sanctions by the United States and European Union. Mwana Africa has warmly welcomed the decision by the government of Zimbabwe in its 2014 Mid-Year Fiscal Policy Review Statement to reduce the royalty on Zimbabwean

gold producers from 7% to 5%, effective 1 October 2014.

Mwana has an 85% interest in, and operates, the Freda Rebecca gold mine at Bindura in Zimbabwe’s Mashonaland Central province. Mwana CEO Kalaa Mpinga commented, “We have actively engaged with Government on this issue and it is very pleasing that – in a spirit of understanding and cooperation – it has recognised the challenges inherent in the gold mining industry at present. “The reduction in the gold royalty rate will provide a welcome financial boost to Freda Rebecca and Mwana,” said Mpinga.

ZAMBIA Zambia’s energy minister called for dialogue between Copperbelt Energy Corp and Vedanta Resources to end a power supply dispute that has paralysed the British mining company’s operations. In September, Copperbelt Energy cut power to Vedanta’s Konkola mine for all but essential operations such as water pumping, ventilation and the operation of medical facilities.

Konkola, one of Africa largest copper producers, lost 482 tonnes of copper output worth $3.3 million after the power restrictions in September. The restrictions to power supply at Konkola Copper Mines comes amid a dispute over an increase in tariffs by Copperbelt Energy, according to reports. The power supply restriction was greatly impairing KCM’s production

AFRICA ROUND-UP

and profitability and may have implications for job security if prolonged, said the miner. Konkola, which produced 160 000 tonnes of copper in 2013, also owns a tailings leach plant, a smelter at Nchanga and a refinery at Nkana. The merger of ASX-listed companies Blackthorn Resources and Intrepid Mines will create a well-funded copper company that will see the completion of the Kitumba copper project in Zambia. The merged group is expected to add significant value to the project that is currently undergoing a definitive feasibility study, with construction of the new copper project to begin in the first half of 2016. Speaking at the Paydirt 2014 Africa Down Under Conference, in Perth, Australia, last week, Blackthorn Resources CEO Mark Mitchell said the project had a $680 million capital cost and a net present value of $461 million. Mitchell also noted that the Kitumba project had an 11-year mine life and was expected to produce 56 000 t/y of copper.

the ship loader would help the company’s operating plans to increase production for the shipment of iron ore from Liberia through the Buchanan port. The arrival of the ship loader is in preparation for Phase 2 of ArcelorMittal’s Liberia operation and is set to increase the company’s capacity to meet the demands and vision for operations in Liberia. A group of eleven mining and related companies operating in West Africa called on the international community to step up the fight against the Ebola outbreak in Sierra Leone, Guinea and Liberia. Eleven CEOs released a joint statement in September expressing concern and highlighting the impact of the Ebola virus on affected countries’ economies and the well-being of their people.

“Our companies have made long-term commitments to these countries and their people and we intend to honour these commitments,” declared the CEOs of African Mining Services, ArcelorMittal, Aureus Mining, Dawnus Group, Golden Veroleum Li-

beria, Hummingbird Resources, Iamgold, London Mining, MonuRent, Newmont Mining and Randgold Resources.

TANZANIA Tanzania’s state mining (SMC) subsidiary Stamigold is planning to expand production at its Biharamulo gold mine to reach 40 000 oz of gold in 2015. Tanzania’s government bought the Tulawaka gold mine from African Barrick Gold in November, and renamed it Stamigold Biharamulo. The projected quantity at Biharamulo is four times that of the company’s expected production capacity for this year. “We have started mining a new open pit and extended the life of the mine for three more years,” SMC acting managing director Edwin Ngonyani told Reuters. Ngonyani said SMC is still doing some more exploration work and there is a possibility that the LoM could be further extended if sufficient gold reserves are found. After re-

starting the mine last month, the government aims to produce 10 700 oz of gold this year, a decline from the 44 338 oz and 84 101 oz of gold produced in 2012 and 2011 respectively. The mine is located in the gold field region near Lake Victoria in Tanzania. Kibo Mining’s Rukwa coal project has been boosted by a study that showed the mine in Tanzania could support a 300 MW mine-mouth power station. The early assessment of the technical and economic viability of the Rukwa coal mine was confirmed as a suitable fuel source for the 300 MW minemouth coal-fired power station, said Kibo Mining. The result of the preliminary economic and technical evaluation is part of the definitive mining feasibility study for the Rukwa coal project. The indicative life of plant for the Rukwa Power Station requires 28.8 Mt of coal over 20 years, which amounts to only 48% of the currently mineable resource of 60 Mt for the Rukwa coal mine.

Ghaghoo mine in Botswana

LIBERIA Steel producer ArcelorMittal, in September, imported a shiploader valued at $30 million to boost its operation in Liberia. Weighing over 400 tonnes and billed as the largest piece of steel structure to ever enter and be installed in Liberia, the shiploader docked on 5 September at the ArcelorMittal Liberia Buchanan iron ore port.

ArcelorMittal commissioned the equipment to sustain its operations in Liberia despite the outbreak of the killer Ebola virus that has impacted on the local economy.

ArcelorMittal CEO Antonio Carlos Mario told media on 9 September at the port of Buchanan city in Liberia that IN SID E M IN IN G 1 0 | 2014

7

COVER STORY

Brains, and brawn, The ability to successfully develop and deliver a specialised lifting solution was demonstrated in the heavy-lift operation undertaken by Johnson Crane Hire at Sasol’s Secunda plant recently. And, it was by no means a small feat.

T

HERE ARE SOME jobs that need intimate knowledge and experience to be successfully completed. As James Robinson, heavy-lift manager for crawler cranes and projects at Johnson Crane, pointed out, the lifting job at Sasol’s Secunda plant, was just such a job for the project’s engineering, procurement and construction manager, Fluor. Extensive years of collaborative experience, coupled with a solid track record, enabled Johnson Crane to safely complete the task nine days ahead of schedule.

“Extensive time was spent on evaluating the site conditions and Johnson Crane considered the customer’s needs when putting the proposed solution into place.

We were fully aware of the urgency of the project and knew that we needed to

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INS I DE MI N I N G 1 0 | 2 0 1 4

provide value to the customer in terms of completing the lift as quickly as possible. This was underlined by the necessity to allow the other contractors to start on their portions of the shutdown work,” Robinson explained.

The lift had to be conducted during shutdown of the plant, which obviously had strict time constraints, so it was necessary to provide an efficient lifting solution that would remove the vessels in the shortest possible time without compromising safety.

The scope of the project entailed the removal of three vessels for the gas-heated heat exchanger reformer project on the gas reforming plant at Sasol Secunda. All three vessels were housed within the plant structure, which is also fitted with cabling, racking, pipework and

ancillary equipment. Two identical waste heat boilers measured 17 m in length and 2 m in diameter, with a mass of 60 tonnes each, while the third vessel had a length of 8 m and a diameter 2.5 m. This vessel was mounted on concrete plinths standing 3.5 m high. Previous attempts at removing these vessels during a prior shutdown had proved very costly due to valuable time being wasted.

As with any shutdown, Johnson Crane was aware that once access was granted, the site would quickly become congested with numerous contractors, erecting items such as scaffolding. This prompted the company to leverage its previous experience on challenging lifts to provide an alternative lifting solution.

Robinson explains that this solution viewed the smaller vessel and its two

COVER STORY

won the day concrete plinths as a single unit. Johnson Crane designed, engineered and manufactured a steel bracing system that would allow the steam drum and its concrete plinths to be removed in one piece.

The bracing system was assembled around the vessel and plinths to provide the necessary stability. Once this was accomplished, a demolition contractor was deployed to cut the plinths at their bases.

At this point, the base was jacked to provide sufficient clearance for the vessel and its plinths to readily pass the existing concrete structure on the plant floor.

“The weight was transferred onto the sliding rails using jacks and then the combined unit of the vessel/concrete plinths was slid out of the plant to a position where crane access was possible. The vessel and concrete plinths were then lifted out of the plant using a JCH 550 tonne mobile crane,” he continued.

The remaining two vessels were removed from the steel plinths on which they were mounted, and removed from the plant using the same sliding system. Once overhead clearance was available, these vessels were lifted using the Johnson Crane mobile crane. Each individual lift was completed within a day.

Robinson points out that careful attention to detail and planning were necessary to ensure that the sliding system could be assembled inside the constrained work area, within the available time frame. In addition to the severe time constraints, the project called for careful attention to uncompromising safety levels and adherence to the necessary legislation.

“In order to achieve a careful balance between all these elements, the time spent in preparation was considered critical to the success of the lift. To the untrained eye, lifts of this nature appear effortless but people are often not aware of the intricate planning that a lift entails. It is merely the mechanics of the lift that happen on the day; the actual theory of the lift is completed far in advance of the physical lift,” Robinson said.

“Although three vessels were removed during this lift, it was the lifting solution applied to the lighter of the three that allowed Johnson Crane to provide the greatest value to the customer in terms of time saved. We have undertaken numerous lifts for Sasol on shutdowns and our understanding of the organisation made it easier for our engineers to plan the various activities within the available windows of

opportunity. The final result saved cost and time on a lift that was expedited in a safe and efficient manner,” he concluded.

OPPOSITE A Johnson Crane’s 550 tonne mobile crane with a luffing boom was set up to remove heavy components from within the plant ABOVE The rail set-up used to move the 17 m by 2 m waste heat boilers BELOW The sliding rail system for the removal of the smaller vessel and its two concrete plinths

IN SID E M IN IN G 1 0 | 2014

9

DIAMONDS

Airborne gravity gradiometry systems An innovative approach to gravity gradiometry surveys for kimberlite exploration is presented. Airborne surveys provide unique advantages for coverage and access efficiency.

By DJ DiFrancesco, Lockheed Martin

F

IXED-WING, ROTARY-WING and airship systems have been used in gravity exploration programmes over the past 16 years – with varying results. Key performance parameters for effective surveys include high spatial resolution, low sensor noise, operational efficiency, and reasonable cost.

These are typically achieved by slower speeds, lower altitude operation, stable platforms, and long endurance. Identifying and qualifying appropriate sensors and air vehicles will yield improved survey performance. In the mid-2000s, aerial gradiometry surveys using a Zeppelin airship were conducted by De Beers in Southern Africa. These surveys demonstrated excellent performance and validated the airship concept. Operational limitations experienced in these previous surveys have been overcome by the development of

new, hybrid airship systems. In addition, enhanced gravity gradient sensors have been developed to provide reduced noise and improved resolution. The combination of these advanced sensors and platforms will be shown to provide a unique exploration capability.

Gravity gradiometer systems Since initial operational deployment in 1998, commercial airborne gravity gradiometer systems have been continually improving in operational performance.

Part of this is due to simply understanding the airborne environment and flying surveys with greater attention to the influences of turbulence and vertical accelerations. Additionally, improvements

FIGURE 2 (top) 3D inversion of airborne gravity gradiometry data in mineral exploration. Source: Geoscience World

in data processing and correlated noise reduction have yielded sizeable gains in overall performance. Table 1 provides a look at the representative system noise and operational characteristics as experienced in various air vehicles (Dransfield & Christensen, 2013). In general, it can be stated that the typical survey noise from a fixed-wing aircraft has been reduced from about 20 eotvos in 1998 to less than 3 eotvos today, due to operational and data processing improvements (see Table 2).

Some of the data processing advances include the use of full tensor noise

TABLE 1 Comparison of flight characteristics, safety and cost for aircraft that have been used for gravity gradiometry surveys

Aircraft

Style

Survey speed Minimum survey Comparative Stability (m s-1) height (m) safety

Comparative cost

C208 AS350 CASA DASH-7 BT-67 Twin Otter Zeppelin

Fixed wing, single engine Helicopter, single engine Fixed wing, twin engine Fixed wing, four engine Fixed wing, four engine Fixed wing, twin engine Airship

60 35 60 85 55 – 17

Low High Medium High High Medium High

10 INS I DE MI NI NG 1 0 | 2 0 1 4

Good Good Good Very good Very good Very good Best

60 35 60 – – – 80

Good Good Good Good Good Good Poor

DIAMONDS

reduction, a process employed by Bell Geospace; regularised 3D inversion, regularised focusing inversion, and potential field migration – all developed by TechnoImaging; and integrated interpretation services developed by ARKeX (DiFrancesco, 2013). The benefits of flying lower and slower have also been documented by CGG’s Heli-Falcon system, which claims typical filtering at 90 m wavelength, resulting in 45 m along-line spatial resolution (Christensen, 2013).

Air platforms The critical parameters for a successful kimberlite exploration survey using gravity gradiometry include safety, high signalto-noise ratio, low altitude, slow speed, and reasonable cost. Two unique and modern platform configurations are presented here to address the challenges for high-resolution surveying for kimberlites.

Advanced rotorcraft A remotely piloted rotorcraft called the K-Max has been developed by Kaman Aerospace and Lockheed Martin. This system, using counter-rotating blades and autonomous control, has been used in replenishment and logistic missions in various world theatres of operation since 2011 (McCarthy, 2013). This system has a 2 700 kg payload capacity, can fly unmanned over areas of heavy terrain, and operate either in daytime or at night. The benefits of low and slow flying, in addition to the safety advantages of pilotless operation, make this an ideal platform for geophysical exploration. The flight operation costs of about $1 300 per hour make this a relatively cost-effective survey platform on a recurring basis (see Figure 1).

Hybrid airships The hybrid airship is a well-suited air platform for geophysical exploration, including kimberlites. Some of the advantages of such a system include the ability to remain airborne for long periods of time, hold position without being tethered, and withstand strong winds. Some additional benefits of modern airships

include superior aerodynamic design resulting in high performance, the ability to be assembled on-site and launched within hours, carry a wide range of payloads, and in the case of the GNSS StarShadow, are solar powered and use no petroleum-based fuels (Oholendt, 2012). They can operate from existing infrastructure or service remote points of need with austere infrastructure. Hybrid airships under development today include versions that can be remotely or optionally piloted.

Hybrid airships, which get their name because they employ both buoyant and aerodynamic lift, are under development in numerous places. Two examples are the GNSS StarShadow and the Lockheed Martin P-791. Possibly the best characteristic of the hybrid airship is that it produces a very smooth ride for the equipment payload and on-board operators. This reduced dynamic motion has direct benefit on the gravity gradient measurement as noise increases as a function of vertical acceleration. Figure 3 shows a comparison of the vertical acceleration spectrum from a Cessna Grand Caravan and a Zeppelin airship survey (Hatch, 2007). The vertical acceleration, measured in mg’s, is up to five times less in the airship than the fixed-wing Caravan.

FIGURE 3 (above) Comparison of vertical acceleration (milli-Gs) for a Cessna Grand Caravan (lighter lines) and a Zeppelin airship (darker lines) FIGURE 2 (below) Cessna 208B Grand Caravan FIGURE 1 (bottom) K-Max unmanned rotor craft in typical replenishment mission

operational control and advances in data processing. Deployment on an advanced platform such as a rotorcraft or hybrid airship will yield significant benefits for future kimberlite exploration programmes.

Conclusions Present-day gravity gradiometer systems have demonstrated excellent noise and resolution characteristics. Improvements have been realised from improved

TABLE 2 Achieved noise levels for gravity gradiometer systems in various aircraft

Aircraft

Speed knots

Sampling rate (m)

Tzz residual noise roof level, Eo2 km

Tzz detectability

Cessna Grand Caravan surveys 2004 Cessna Grand Caravan surveys 2006 Cessna Grand Caravan surveys 2010 BT67 Surveys 2010 Zeppelin NT

120 120 120 105 30 to 35

62 62 62 55 15 to 18

2>0 ~10 7 to 8 <6 <2

5 Eo over 400 m 3 Eo over 300 m 2 Eo over 300 m 2 Eo over 200 m 1.7 Eo over 100 m

IN SID E M IN IN G 1 0 | 2014 11

DIAMONDS

To mine or not to mine In diamond mining, errors can be extremely costly. It’s a case of having to get it right the first time. We look at the resource definitions for the Middle Orange River, based on redefined geological areas. By G Stevens, Rockwell Diamonds

T

HE RESOURCES estimates for the Rockwell gravel deposits are based on specific parameters under which the exploration, bulk sampling and economic conditions need to adhere to set guidelines to be rated as either an inferred resource, indicated resource or probable reserve.

Historically, the approach to alluvial resource definitions has been largely focused on defining a ‘regional’ area, i.e. a palaeo river terrace on a specific elevation or specific depositional areas within a marine deposit and rating it as an inferred or indicated resource. This approach, followed according to industry requirements, states the volumes, grades and diamond values of the resources found on the Rockwell mineral right areas. The depositional environment, gravel quality and diamond source play a large role in determining these resource valuations and, as a result, Rockwell has found the need to redefine the resources estimates based on defined geological areas within the stated resource areas.

Aim The aim is to redefine the depositional environment based on the local geological features and diamond valuation. A gravel rating scheme has been implemented on each of the mines. This rating scheme takes into account the fixed and mobile trap sites, and gravel quality (coarseness, matrix, sorting, etc.), which then allows for the application of a better resource valuation within those areas.

Approach Due to the large variability within the terraces, the need was identified to quantitatively measure specific attributes within the depositional areas or gravel at a specific point in time. Daily geological observations, coupled with data reconciliation, have allowed Rockwell Diamonds

12 INS I DE MI NI NG 1 0 | 2 0 1 4

FIGURE 1 (right) Middle Orange River terraces defined per elevation area FIGURE 2 (middle right) Large stone plots and a simplified gravel bar position interpretation FIGURE 3 (bottom right) Grade plot. Notice the variation and large areas used within the plot (the depositional area is not taken into account)

to build a database of these attributes.

In order to quantitatively ‘measure’ gravel quality, the gravel priority rating scheme was developed.

This tool takes into account the gravel characteristics as defined during an extensive development phase in which the properties within the gravel were specified and then plotted daily so as to ascertain which parameters held weight or consistency and which did not.

Measurable areas that allow for better definition have been used; these are: • position on the gravel bar • large boulder size • average clast size • gravel fabric • BIF/basalt % vs BIF/ zeolite % • BIF % • clast shapes In addition to the GPR, the following depositional attributes are also taken into account to define the: • grade per area • large stone plot.

The large stone plots are used to define the area within the depositional area. This allows to identify the possible extents of the grave bars (Figure 2).

DIAMONDS

TABLE 1 Middle Orange River gravel priority rating scheme

Position on bar

Large Average clast Gravel boulder size size range fabric

Mobile Trapsite (upper)

Mobile Trapsite (basal)

Bar head (3) > 400 mm (3) Riffle Platform (2) Bar tail (-1)

256 - 400 mm (2) < 256 mm (1)

Total out of Total out of (3) (3) Bar head (3) > 400 mm (3) Riffle platform (2) Bar tail (-1)

256 - 400 mm (2) < 256 mm (1)

Total out of Total out of (3) (3)

Cobble-boulder (4) Cobble-pebble (3) Pebble-cobble (2) Pebble (1) Total out of (4) Cobble-boulder (4) Cobble-pebble (3) Pebble-cobble (2) Pebble (1) Total out of (4)

BIF/basalt % vs BIF % BIF/zeolite %

Clast shapes

Boulder

BIF/High basalt (2)

Discs (3)

Cobble (1)

BIF/High Zeolites (0)

Pebble (1) Grit (1) Total out of (4) Boulder (1) Cobble (1)

Total out of (2) BIF/High basalt (2) BIF/High Zeolites (0)

Pebble (1) Grit (1) Total out of (4)

Total out of (2)

Results Mobile Basal Trap Site out Upper Mobile Trapsite out of (22) of (22) Total 0 0 Percentage 0.00% 0.00% Normalised Rating For Both 0.00% Trap Sites (50%) Weighted Rating For Both 0.00% Trap Sites (Fixed 60%) Rating for the Day (if only one trap site was rated)

The average grade per area has been used as an indicator to the possible grades expected in the adjacent blocks. This is flawed in that it does not take into account the actual position of mining within the depositional environment (Figure 3).

Findings

FIGURE 4 (top) Gravel priority rating for BHC FIGURE 5 (above) Gravel priority rating for SHC

The implementation of the rating tool has proven a challenge. Correlation between the rating percentage and the actual grade recovered from varies twofold in that: • the tool has had to undergo various revisions to improve accuracy and sort through the gravel attributes that are consistent and measurable (see the comparison variation between mining and processing areas in Figures 4 and 5) • mining does not always allow for a direct correlation between grade and the rating tool, as there are various areas where stockpiling of product can

High (+50%) (3) Med (30 - 50%) (2) Low (<30%) (1)

Total out of (22)

Sphere/ Discs (2) Sphere (1)

Total out of (3) Total out of (3) High (+50%) Discs (3) (3) Med (30 - 50%) Sphere/ (2) discs (2) Low (< 30%) Sphere (1) (1)

0

Total out of (3) Total out of (3)

0

occur, with a significant gap between rating and processing dates.

The accuracy of the grade plot has been questioned in that large areas are used to define a grade. This limits the interpretation of where one is situated within the depositional environment, or gravel bar.

The large stone plots show the clusters of large stones within random clusters and are continuously used to interpret position within the depositional environment. The drawback of this is that it is a retrospective tool and does not always allow for the interpretation of actual gravel bars sizes.

Conclusion The gravel priority rating scheme, large stone plots and grade plots are all tools that can be implemented to determine where one is situated within a depositional environment, and rather than applying a physical position (related to elevation of the terrace) to supplying a position of where the likelihood of diamond deposition and concentration is to be expected.

The various tools implemented in redefining the MOR gravels have assisted in starting to identify the actual gravel quality within an area. This definition is based on attributes other than exploration data (collar files), and provides scope for improved exploration methodology and input. It also provides the geologist with a base to work from when determining their position within the depositional environment.

More work is needed on redefining larger areas, as the current rating is rather focused on immediate areas.

IN SID E M IN IN G 1 0 | 2014 13

DIAMONDS

Africa’s first microdiamond laboratory The role and function of a specialist exploration, geology, mineral resource and reserve estimation service is invaluable. The MSA Group provides such a service. By H Cronwright and O Garvie

M

SA OFFERS A world-class analytical service to diamond exploration and mining resource evaluation programmes. Its laboratory facilities include a heavy mineral analysis (HMA) laboratory for the recovery of diamond indicator minerals from both exploration and kimberlite samples; and a microdiamond (MiDA) laboratory for processing and recovering diamonds from kimberlite samples using caustic fusion.

SANAS accreditation Both the HMA and MiDA laboratories have been accredited since May 2012 by the South African National Accreditation Standard (SANAS, according to the global ISO/IEC 17025 requirements. The accreditation schedule for the MSA facility (certificate number T0544) covers both kimberlite indicator mineral recoveries down to 0.3 mm from heavy mineral concentrates, as well as microdiamond recovery from kimberlite samples down to 75 micron bottom screen size.

A laboratory quality management system is in place and this provides assurance to our clients and their investors that MSA test results and diamond weighing calibrations are consistently accurate. All samples are sorted and then checked by another mineral or diamond analyst. Apart from FIGURE 1 Cumulative diamond size frequency distribution of N = 279 microdiamonds

14 INS I DE MI NI NG 1 0 | 2 0 1 4

FIGURE 3 (right) Surface textures on kimberlitic spinel grains, showing increased abrasion

these rigorous quality control procedures, regular mineral identification training workshops and competency testing are carried out to maintain proficiency of the mineral and diamond analysts.

MiDA laboratory services In association with SGS South Africa, MSA has established a world-class microdiamond laboratory facility that processes kimberlite samples by caustic fusion for microdiamond recovery. The facility was designed and constructed in 2006, commissioned in 2007 and, over the past eight years, has successfully processed a total of

25.2 tonnes of kimberlite and recovered 26 180 diamonds.

In general, it is recommended to process samples weighing at least 200 kg in order to recover sufficient stones for grade modelling. The sample weight reduction after caustic fusion is typically greater than 99.8%. The small refractory mineral residue produced by the caustic fusion

DIAMONDS

process, weighing approximately 5 g, is then microscopically sorted, by experienced diamond analysts, for microdiamonds down to 75 microns.

Quality control throughout the process is monitored by spiking with sized synthetic diamonds that are easily identifiable. Spikes are perfectly cubo-octahedral synthetic diamond crystals and have a distinctive yellow colour. The synthetic diamond spikes are added to the sample at the start of the caustic fusion process. Diamond spike recovery during the first year of operation of this specialist laboratory facility was established at 95% and set as the minimum standard of diamond spike recovery going forward. In subsequent years, diamond spike recoveries have improved and, over the past five years, spike recovery efficiencies have been maintained at 100%. Synthetic diamonds released into the diamond drilling sample are also identified, stored on sample cards and reported. All macrodiamonds (+0.5 mm in size) and microdiamonds greater than FIGURE 2 Diamond description statistics for N = 541 microdiamonds recovered

300 microns are weighed individually and placed on sample cards for measurement and description. All microdiamonds smaller than 300 microns are weighed in groups per sieve class. The diamond size distribution of 10 samples from an unnamed kimberlite is tabulated in Table 1 and the cumulative size frequency distribution is shown in Figure 1. The diamonds recovered are described in terms of colour, clarity and crystal morphology, and this information can be used to fingerprint diamond populations sampled by the kimberlite (Figure 2).

HMA laboratory In addition to the microdiamond facility, the ISO 17025 accredited HHMA laboratory specialises in the recovery, description and interpretation of kimberlite indicator minerals (KIMs). Competent mineral sorters are able to identify kimberlitic (as opposed to non-kimberlitic or crustal-derived) garnet, spinel, ilmenite and chrome diopsides that are used as pathfinder minerals during kimberlite exploration.

Primary, secondary and abrasion surface textures of KIM grains provide valuable

information to determine if they originated from a proximal or distal source. Figure 3 shows spinel grains with increasing abrasion features on their surface, which indicates further transport from their kimberlitic source.

Certain indicator minerals like chrome diopsides are preferentially destroyed by weathering closer to source than ilmenite or garnet grains, therefore the KIM abundances and types can be plotted on a map to identify target vectors. Mineral chemistry, combined with a surface texture description of grains, can assist in understanding the provenance of mixed populations of indicators to prioritise follow-up targets.

Value-adding services and interpretation The KIMs recovered by the HMA lab can be analysed by electron microprobe and the chemical results evaluated to determine if the conditions of their formation were suitable for diamond formation and subsequent emplacement to the earth’s surface by the kimberlite magma. The diamond potential of the primary source of these KIMs can be modelled from garnet chemistry, using in-house developed software called Diamond Hunter.

If a sufficient number of microdiamonds are recovered (generally more than one stone per kilogram of kimberlite processed), the size frequency distribution may predict a possible macro diamond grade and large stone frequency distribution information.

Conclusion The main benefit of MiDA is that it is cost-effective as a first-stage approach to assess a kimberlite. It can prioritise targets before more costly bulk-sampling is done, or recommend a ‘walk-away’ decision early on. MiDA results can be used later in a mining project to establish the diamond content of each kimberlite phase or domain (in terms of stones per kilogram processed) and help characterise the deposit further.

TABLE 1 Number of diamonds recovered from 10 kimberlite samples, screened according to size fraction (bottom screen size in mm)

Sample ID Size fraction (+ mm)

A

B

C

D

E

F

G

H

I

J

All samples

2.360 1.700 1.180 0.850 0.600 0.425 0.300 0.212 0.150 0.106 0.075 Total #

0 0 0 1 1 1 1 1 1 4 8 18

0 0 0 0 1 1 2 4 6 8 1 13 35

0 0 0 0 0 0 0 1 4 5 6 16

0 0 0 1 0 0 0 1 2 5 7 16

0 0 0 2 0 3 5 5 7 11 15 48

0 0 0 0 0 1 1 3 7 7 9 28

0 0 0 1 0 0 1 1 2 4 7 16

0 0 0 0 0 1 1 2 8 1 13 16 41

0 0 0 1 1 2 1 2 3 6 11 27

0 1 0 0 0 1 1 2 3 10 16 34

0 1 0 6 3 10 1 13 22 43 73 108 279

IN SID E M IN IN G 1 0 | 2014 15

SHAPING UNIQUE

SOLUTIONS THAT SHINE

AF R I CA

Emerald Risk Transfer is currently the largest

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business throughout the African Continent.

The solution orientated approach of the Emerald team to create sustainable, quality products is part of their culture. / Ã yiÝ L i >««À >V ] V Õ« i` Ü Ì Ì i ÃÕ«« ÀÌ v Ì i À iÝVi i Ì ,i ÃÕÀiÀ «> i ] > ÜÃ iÀ> ` Ì Li ÌÀÕ Þ innovative.

The aim of the company is not to be the cheapest by cutting V À iÀÃ] LÕÌ À>Ì iÀ Ì Li Ì i LiÃÌ LÞ vviÀ } iÝ«iÀÌ Ãi and skill.

iÀ> ` , Ã /À> ÃviÀ Ã > Ü Þ Ü i` ÃÕLÃ ` >ÀÞ v Ì i Santam group. Santam Limited is a level 3 BBBEE company, and has a Standard & Poor’s international rating of BBB+ > ` > >Ì > À>Ì } v čč³] Ü Ì > ÃÌ>L i ÕÌ °

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E

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Emerald is a fully intermediated company and underwrites exclusively for Santam Insurance Ltd. With a Standard and Poor’s international rating of BBB+, national rating of ZaAAA, and assets in excess of $2 Billion, Santam is South Africa’s leading short-term insurer.

Emerald prides itself on employing highly skilled and experienced technical and underwriting people, which we believe are among the best in the corporate property insurance sector in Africa. Backed by skilled and experienced claims technicians and professional engineers, our underwriters are able to find solutions for even the most complex risks. Our team has considerable experience, and has seen most risks in Africa in one form or another.

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to become the reinsurer of choice on the African continent.

Correct understanding and measurement of risk, appropriate reinsurance placement and accounting and effective claims management are all key to Emerald’s underwriting approach. Specialising in large and complex risks, Emerald’s bespoke wordings provide a wide and complete range of covers.

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“Correct understanding and measurement of risk, appropriate reinsurance and accounting and effective claims management are key.”

Bernard Ray, CEO, Emerald Risk Transfer

IN SID E M IN IN G 1 0 | 2014 17

DIAMONDS

Diamonds on the soles of its feet Namdeb will use the walking jack-up platform, complete with on-board processing plant, for trials of sampling and mining methods in the surf zones of their concessions. By JM Loubser and IT Mbangula, Namdeb Diamond Corporation

D

IAMONDIFEROUS linear beaches stretching approximately 100 km northwards from the Orange River mouth on the south-western coast of Namibia have been mined continuously for more than 80 years. The narrow coastal strip (ranging between 0.3 km and 4 km in width) hosts a series of linear beaches, ranging in elevation from 30 m above

mean sea level (mamsl) to 25 m below mean sea level (mbmsl). Up to the mid-nineties, mining activities had been predominantly depleting the dry elevated beaches. These beaches have been exposed in the different trenching campaigns and were identified over the entire length of the mining licence (elevation, diamond content and size). As the land-based resources became depleted, the vision of

exploring into the ultra-shallow water became more apparent.

Multiple transgression and regression cycles during the Quaternary period saw the sea level reach as low as -120 mbmsl as recently as 18 000 years ago, and the significant stands in between have been associated with spectacular mineralisation.

Many of these extend seaward of the current high water line (HWL), which is the real potential of the ultra-shallow area.

Historic attempts Attempts to prove the presence of diamonds go back to the early 1960s when mining equipment was used to access the gravels, especially during neap tides.

A platform with two jet pumps attached to excavator booms operated in the early 2000s as an attempt to evaluate the ultra-shallow area. Some diamonds were recovered but it was not sustainable and a different method of resource development was required. These initial attempts were focused in the shallower northern areas of the license area where limited overburden is present. No work was done in the southern resource area where the overburden was in access of 15 m except for land-based mud and air core drilling.

These land-based methods, however, were unable to cross the physical barrier presented by the HWL.

Dredging and mining ultra-shallow water areas Onshore mining activities, during which the stripping of overburden is used to build seawalls, then eroded and deposited LEFT The probe drill platform in action ABOVE LEFT Probe drilling platform’s operating environment and limits

18 INS I DE MI NI NG 1 0 | 2 0 1 4

DIAMONDS

LEFT Namdeb mining licence areas BELOW The potential economic benefits from the CSIR/WSP accretion models are significant

conventional onshore mining techniques and, by 2013, the deepest mining face was in the G90 area, Mining Area No 1, where depths of 28 m below MSL were reached.

This was associated with spectacular diamond recoveries.

Resource development and risk

with the long shore drift, have caused significant accretion over the years. Fine tailings of millions of tonnes of annual head feed that is pumped out to sea also contributes significantly. The CSIR (and later WSP) has been monitoring this process annually. A major milestone in the history of accretion was the introduction of the dredging project that commenced in 1997, which deposited in excess of 63 million tonnes of overburden sands (excluding oversize) on the beach between G60 and G100.

The accretion has given access to previously submerged beaches using

A method of proving the existence of offshore diamondiferous gravel was required. The trend of mining-accreted areas became standard practice and, in 2005, the risk started becoming uncomfortable.

As mining proceeded westward into the accreted areas, the discontinuation of the ore body could have resulted in a financial disaster. A tool that would be able to sample the ultra-shallow water zone was needed urgently, to drill ahead of mining.

Operating drilling and sampling tools in the vigorous swash zone of the Atlantic coast of Namibia was always a technical challenge and a significant amount of R&D took place. The requirement was to do basic resource delineation with bedrock elevation and the presence of marine gravel as the two key deliverables.

Probe drill platform A custom-designed probe drill platform (PDP), a walking-jacking platform, was developed between 2008 and 2010, and put to trial in the areas with limited overburden during 2011. It is equipped with a reverse circulation drill as the only on-board tool. The PDP is designed to

walk from land to sea making use of an eight-legged sliding platform that is capable of moving in one direction only. It can operate at water depths of 4 m, in swells of up to 4 m, and travels at 10 m/hour.

Personnel travel to the PDP via the aerial ropeway system, which had a maximum reach of 350 m but was later reduced to 250 m. The PDP was deployed in the G50 area approximately 4 km south of G90 within Mining Area No 1. The first line was drilled in 2012 and the continuation of the ore body (presence of marine gravel) was confirmed. Subsequently, 12 lines were drilled on a line spacing, which was increased from 200 m to 400 m, whereas the spacing along the line (12.5 m) remained constant. During 2014, the first resource delivery of the area where the PDP drilled was completed and added to the resource inventory in the inferred category of confidence (Mbangula et al., 2014). This made use of different exploration methods (PDP percussion drilling, BG36 bucket auger sampling and sonic drilling) for the first time at Namdeb and paved the way for the next phase of resource delivery to take place in the ultra-shallow waters ahead of the accretion.

Unlocking the future With the PDP now one of the prime exploration tools in Namdeb’s stable, plans to actively accrete is a reality. Previously stripped overburden available in the southern 40 km of Mining Area No.1 has been identified as a massive resource to be used in this process, making the areas drilled by the PDP accessible for conventional mining.

Confirming the geological model and presence of marine gravel 250 m west of the current HWL have opened the next chapter in the life of the legendary Mining Area No.1 deposit, the ‘Grande Dame’ of the Namdeb Mining Operations, potentially adding at least another 15 years of mining.

References • Hallam, CD. 1964.The geology of the coastal diamond deposits of Southern Africa.

In: Houghton, SH (ed.). The geology of some ore deposits of Southern Africa 2. 671-728.

Geological Society of South Africa.

• Mbangula, IT, Van Dyk, F and Jordaan, L. 2014. Geology and Estimation Report, BG36 sampling and PDP drilling in the Western blocks and Ultra shallow water. G30 – G60 area, MA1. Docs 108655. Namdeb internal report.

IN SID E M IN IN G 1 0 | 2014 19

DIAMONDS

Steadily towards the future The ever-competent Paul Sobie provides an update on developments att the Lace Diamond Mine near Kroonstad. All said, everything is on track and yields are positive.

E

VEN THOUGH the mine’s development is ongoing, production recoveries for the three months ended 30 June 2014 totalled 6 102 carats at a recovered grade of 6.32 cpht. In addition, a 15.2 carat, clean white octahedral diamond was recovered from the tailings, the largest gem diamond the mine has recovered to date.

significant additional cash flow which would allow the Bulge to be bulk tested and (if warranted) financed from internally generated cash flow, whereas mining of the Bulge alone would require additional project finance. Further, the UK4 Block has the potential to provide high-grade ore while the 47 Level Block cave is developed and matured, and flattens out the potential lumpiness in tonnage which can occur

Underground Development Core drilling of the mine’s Bulge area provisionally indicates that the zone is largely lower grade (volcanoclastic) kimberlite.

This means that the total recoverable diamond content is likely to be significantly less than the UK4 Block. Mining of the UK4 Block has the potential to provide

Photographs taken by Wolfgang Hampel

20 I N SID E M IN IN G 1 0 | 2 0 1 4

ABOVE Typical, potentially diamondiferous kimberlite from the Lace mine. The kimberlite contains xenoliths of the overlying Karoo basalts. Width of sample approximately 25 cm BELOW Entrance to the new underground Lace Diamond Mine. Mining of the underground ore will start in April 2011

DIAMONDS

in the early stages of block caving. For these reasons, the UK4 Block is considered a high priority development target, and the zone where underground production drilling will now concentrate.

A revised underground development schedule and budget aims to bring forward the ramp up of commercial production from underground kimberlite mining by six months into the first half of 2015.

The accelerated mining development will be financed from within existing project finance facilities.

To achieve mine production from the UK4 block, 1 149 m of waste development and 880 m of Kimberlite development is planned over the next 12 months at a budgeted cost of R75 million (R37 000 per metre).

Development not common to both the UK4 Block and the 47 Level Block cave has been rescheduled to occur after mining of the UK4 Block commences.

Overall, mine development costs to date are averaging R37 051/m against a budget of R35 327/m. The 5% over spend is largely a result of a rising operating costs of the company’s underground mining fleet.

The cost increases are a result of increased tyre wear in the final uphill sections of the decline development and higher diesel, repairs and maintenance costs as waste-hauling distances increase. Winter months are also the peak period of the year for electricity tariffs in South Africa.

Management considers that there is scope to reverse this cost increase and has instituted operational efficiency projects in mining, maintenance and procurement to improve productivity and reduce costs.

However, until any improvements are achieved, a new development budget of R37 000/m has been adopted for the UK4 development going forward which can be accommodated from

LEFT General view of the old opencast at the Lace mine. This hole was dug intermittently between 1896 and 1930.

The hole measures some 130 m in diameter. The main kimberlite pipe itself measures approximately 1.5 hectares.

The overlying rocks are Karoo basalts and andesites

existing contingencies. Approximately 55 000 tonnes of kimberlite will be mined as part of the UK4 development, which will be processed in batches in a controlled bulk test supervised by MPH Consulting.

DIAMONDS

LEFT View of the tailings derived from late 19th/early 20th century opencast mining. The tailings still contain appreciable amounts of diamonds and are currently being re-processed BELOW View of the Lace Diamond Mine’s slimes dam. If any diamonds have escaped the processing of the ore, they must be very, very small. The dam has become a refuge for birds, including flamingo

The recovered diamonds will be valued and sold as part of the company’s established sales cycle. The resulting grade and carat value will allow for an upgraded SAMREC-compliant resource statement to be issued in the first quarter of 2015. Management considers it more meaningful to delay the updated resource statement to incorporate the bulk test results than to issue an interim estimate based on micro-diamond analysis alone. Revenue generated from the diamond sales during development and bulk testing will be credited to development costs.

Underground drilling of the UK4 block continued during the quarter, and approximately 600 kg of core samples were submitted for microdiamond analysis. Results received to date continue to confirm that recovered grades of up to 60 cpht can be expected from the K4 Kimberlite.

Scoping and mine design studies have been completed based on approximately 1.5 million tonnes to be mined from the block above the 365 m level which is in addition to the existing geological resource.

The studies recommend bottom-up, long hole open stoping as the mining method and estimate that the steady state production of 30 000 tonnes per month can be achieved by the second half of 2015, with the potential for this to double after development and conveyor belts for the 47 Level Block cave are installed past the 365 m level. Mining and processing costs at the initial production rate are forecast at R169/t.

The design and detailed drawings for the underground conveyor belt system have been completed under budget. Installation of the conveyor belt is underway and is scheduled to be commissioned in H1

22 INS I DE MI NI NG 1 0 | 2 0 1 4

2015 in time for accelerated mining of the UK4 block. The company has experienced no labour issues and continues to hire the personnel it requires. The labour force at 30 June 2014 totalled 287. Safety remains a major priority for the company, with the lost time injury frequency rate for the year to date standing at zero.

Tailings retreatment A decision was taken to reduce tailings re-treatment processing rates and divert the surface earth moving fleet to building another 150 000 m3 surface process water dam. This activity needs to be completed in the dry winter months ahead of rains commencing later in the year.

As a consequence, the plant processed 96 490 tonnes of tailings in the period against a budget of 205 000 tonnes.

Pleasingly, diamond recoveries totalled 6 102 carats as recovered grades were 6.32 cpht against a budget of 5 cpht. This month the company recovered a 15.2 carat clear white octahedral diamond from the

dumps. This is the largest gem diamond recovered to date from the tailings and demonstrates the plant’s efficiency in recovering larger diamonds as well as the smaller size fractions.

The reduced production rate in the last quarter allowed for the de-grit circuit to be installed, which is efficiently removing the fine sand fraction and allowing for approximately 90% of the tailings diamonds to be recovered from 60% of the tonnes previously reporting to the dense media separation plant, thereby reducing operating costs per tonne and improving the stone size average and carat value of the diamonds recovered.

Diamond sales (+1.5 mm) for six months ended 30 June 2014 totalled 14 583 carats for proceeds of $909 611, equating to an average sales price of $62 per carat. At the reduced production rate, the tailings retreatment operation is breaking even and the plant is now operating in the optimal configuration for processing kimberlite from development as this ramps up over the next six months.

Demand for good quality rough diamonds remains relatively strong and prices are 5 to 10% over the prices achieved in December 2013. The company is forecasting the market to be steady to modestly higher for the balance of 2014, with potential for price strengthening in 2015 as world economies continue to recover.

DIAMONDS

Pangolin: a leading exploration company The discovery of the lower mantle-derived SWS 21 intrusion in the Mmadinare area of Botswana has created much interest in the diamond industry.

By LRM Daniels and O Kufandikamwe

T

HE MMADINARE area in north-eastern Botswana is located to the west of the Cu-Ni Selebi Phikwe mine and is situated in the southern and central zones of the Limpopo Mobile Belt (LMB), which extends northwards between the Kaapvaal and Zimbabwe cratons. The area has been prospected for diamonds by at least two major companies in the past three decades with no success. Historically, the area was subjected to soil sampling. Two styles of soil samples were collected – stream sediment samples and loam samples. The size fraction of the soil samples were between 0.425 mm and 2 mm. Although garnet, spinel and picroilmenite were found, no significant numbers of traditional kimberlite indicators were recovered during these historical exploration programmes.

Satellite imagery

TABLE 1 Representative concentrate mineral compositions from the SWS 21 intrusion

Mineral

OLV PILM

SPN

SPN

CPX

CPX

GAR

GAR

GAR

Si02 TiO2

40.09 0.02

0.03 0.31

0.02 0.36

54.98 0.21

54.47 0.06

40.92 0.04

41.75 0.02

40.61 0.19

Al2O3

50.12 0.05

28.43

16.42

2.28

2.48

23.28

20.74

17.21

0.02 Cr2O3

0.05

29.98

41.74

0.59

1.86

0.11

3.95

8.28

0.69 Fe2O3

–

10.09

10.60

–

–

–

–

–

9.18 FeO

10.03

18.58

21.53

4.61

1.67

16.10

8.68

7.72

MnO

31.71 0.13

0.31

0.40

0.14

0.07

0.45

0.47

0.49

0.60 MgO

48.72

11.45

8.29

18.46

15.05

14.57

19.07

18.92

7.35 CaO NiO Na2O Total

0.11 0.40 0.01 99.61

N.D. 0.31 – 99.49

0.01 0.18 – 99.55

15.74 0.08 1.72 98.81

21.30 0.04 2.05 99.05

5.14 – 0.03 100.64

5.47 – 0.02 99.54

6.13 – 0.02 99.57

99.67

With more recent access to satellite imagery via Google Earth, it is possible to review any given area in Botswana with great detail. One of the advantages of using Google Earth is that it is possible to change the scene viewed between different time shots, presenting the opportunity to view the same area during different seasons. In an area that suffers from droughts and has a very different vegetation pattern between winter and summer, this is a very useful exploration tool.

A study was conducted over known kimberlites within the central and northern zones of the LMB with the object of FIGURE 1 The SWS 21 geobotanical feature observed utilising Google Earth satellite imagery

IN SID E M IN IN G 1 0 | 2014 23

DIAMONDS

TABLE 2 Manganoan Ilmenites from the SWS 21 Intrusion, Mmadinare, Botswana

Mineral

ILM

TiO2 48.15 0.10 Al2O3 ND Cr2O3 7.57 Fe2O3 FeO 42.66 MnO 0.63 MgO 0.04 CaO ND 0.06 Nb2O5 Total 99.21 ND = Not Detected

ILM

ILM

ILM

ILM

49.80 ND ND 6.05 43.51 0.77 0.27 0.01 0.02 100.43

48.95 0.04 ND 7.04 43.13 0.86 0.03 ND ND 100.05

49.26 0.04 ND 6.48 43.03 1.06 0.12 ND 0.03 100.02

47.43 ND 0.03 9.85 40.52 2.10 0.01 ND 0.07 100.01

identifying any geobotanical anomalies associated with the known kimberlites.

In particular, the Mwenezi (Williams and Robey, 1999) and Mambali-Ngulube kimberlite fields, discovered by De Beers and Trillion Resources from Canada, respectively, were studied. Based on the observations made over these kimberlites, a detailed Google Earth study was undertaken over the Mmadinare area and in excess of twenty targets were identified for ground follow-up.

Trace elements The paucity of traditional kimberlite indicator minerals (KIMs) recovered from the Mmadinare area, during previous exploration programmes that sampled the area extensively, indicated that traditional soil sampling was not the route to follow in this area. Recent advances

FIGURE 2 Trace element results from 22 targets identified in the Mmadinare area, Botswana, from Google Earth imagery. (A) Ni (ppb); (B) Y+La+Nd (ppb), (C) Sr (ppb) and (D) V (ppb)

24 INS I DE MI NI NG 1 0 | 2 0 1 4

in analytical techniques, which allow for the analysis of trace elements in small samples to a parts per billion level, have provided the opportunity to geochemically discriminate between areas of the Jwaneng Kimberlite field and analysed for 72 elements, including V, La, Nb, Nd, LREEs and HREEs, Th, U, Sr, Rb and Ba. A trace element profile was established over these two known kimberlites (Daniels et al., 2012).

The GoogleEarth targets selected within the Mmadinare area were sampled for KIMs and trace element samples, taking one 40 litre soil sample in the central part of the feature. The -2 mm + 0.425 mm fraction was processed through a 1 tph DMS plant for traditional KIMs. No KIMs were recovered from any of the samples.

The -0.425 mm fraction of each sample was screened to -180 microns and 50 g of this size fraction was submitted to Activation Laboratories in Ancaster, Ontario, for trace element analysis utilising an enhanced enzyme leach technique.

Anomaly SWS 21 (Figure 1) was characterised by the most anomalous Ni and

Sr. The sum of Y + La + Nd for SWS 21 returned the third highest value obtained from the trace element samples. V, which was considered to be a significant kimberlite trace element in the Jwaneng orientation survey, was found to be subdued over SWS 21 and marginally above background (Figure 2).

Based on the combination of the Google Earth imagery and the trace element results, a pit was excavated in the SWS 21 feature. A highly weathered rock, light green in colour, with a hand specimen appearance of weathered kimberlite, was intersected at less than 2 m depth.

Petrographically, the rock has been described as an olivine-rich ultrabasic rock with clinopyroxene, phlogopite and apatite. Due to the absence of two generations of olivine, the rock has not been classified as a kimberlite.

Kimberlite indicator minerals Garnet, spinel, picroilmenite, clinopyroxene and manganoan ilmenites have been recovered as indicator minerals from the weathered intrusive rock. The minerals were analysed by microprobe at CF Laboratries, Kelowna, British Columbia.

A total of 19 mantle-derived garnets were recovered from a 20 kg sample. Both eclogitic as well as peridotitic garnets are present. No subcalcic garnets were recovered from this sample. The composition of one knorringite-rich garnet is similar to the composition of garnets from a diamondiferous xenolith from Premier Diamond Mine (Viljoen et al., 2004).

The chromian spinels follow a mantle trend of garnet-spinel peridotites as observed in lamproites in Australia (McCandless and Dummett, 2003; Jacques et al., 2014). Six clinopyrexenes with 0.59 – 2.48 wt% Cr2O3 were recovered and their compositions are consistent with a derivation from garnet lherzolites (Stephens and Dawson, 1977). A forsteritic olivine and one picroilmenite (7.35 wt% MgO, 0.69wt% Cr2O3) were also recovered from the sample (Table 1).

Five manganoan ilmenites recovered from the discovery pit at SWS 21 have compositions consistent with ilmenites recovered as inclusions in diamonds from alluvials and from a Pandrea kimberlite in the Juina area, Mato Grosso State, Brazil. These manganoan ilmenites have a lower mantle paragenesis (Kaminsky et al., 2001, 2009). The ilmenites

DIAMONDS

FIGURE 3 MnO wt% vs MgO wt% plot for manganoan ilmenites from the SWS 21 intrusion, diamond inclusions from Juina alluvials and the Pandrea kimberlite in Mato Grosso State, Brazil (Kaminsky et al., 2001, 2009) BELOW RIGHT A map of Botswana showing Pangolin diamond corp‘s license holdings

are characterised by low MgO (0.01 to 0.27 wt%) and MnO 0.63 – 2.10 wt% and negligible Cr2O3 (Table 2, Figure 3).

Discussion and conclusions The absence of two generations of olivine from the SWS 21 intrusion precludes the rock from being classified as a kimberlite even though it is an olivine-rich ultrabasic intrusive rock with clinopyroxene, phlogopite and apatite containing traditional kimberlite indicator minerals derived from the upper mantle.

The manganoan ilmenites recovered from the SWS 21 intrusion are similar in composition to the Mn-ilmenites that occur as inclusions in diamonds from alluvials in the Juina area of Mato Grosso. The Juina Mn-ilmenites coexist in diamonds with other minerals that are consistent with a derivation from the transition zone at depths of 660 km and the lower mantle (Kaminsky et al., 2001).

One of the garnets recovered from the SWS 21 intrusion is a knorringite-rich pyrope similar in composition to a diamondiferous lherzolite reported from the Premier Diamond Mine, South Africa (Viljoen et al., 2004 ) indicating a derivation from within the diamond stability field. It is concluded that the SWS 21 volcanic intrusion transected the diamond stability field in the upper mantle.

Kaminsky et al. (2001) concluded that Mn-rich, MgO-poor ilmenites should be included as potential diamond indicator minerals and that in such areas where these ilmenites are encountered, the traditional KIMs like pyrope garnet and Cr-spinel may be in the minority or absent. The paucity of traditional KIMs in the Madinare area suggests that the manganoan ilmenites recovered from the SWS 21 intrusion should be considered as an alternative diamond indicator mineral in this area of Botswana.

The combination of Google Earth satellite imagery and trace elements can lead to discovery.

References • Daniels, LRM, De Bruin, D, Smuts, WJ. 2012. Exploration for concealed kimberlites in Botswana with trace element soil geochemistry. Extended Abtract, 10th International Kimberlite Conference, Bangalore, 10IKC-223.

• Jacques, L, Luguet, A, Smith, CB, Pearson, D.G., Bulanova, GP, Yaxley, GM, Kobussen, A. 2014. Nature of the mantle beneath the Argyle Ak1 lamproite pipe: constraints from mantle xenoliths, diamonds and lamproite geochemistry.

Rio Tinto Diamond Volume, Special Publication. Society of Economic Geologists.

• Kaminsky, FV, Zakharchenko, OD, Davies, R, Griffin, WL, Khachatryan-Blinova, GK, Shiryaev, AA. 2001. Superdeep diamonds from the Juina area, Mato Grosso State, Brazil. Contribution to Mineralogy and Petrology. 140:734-753.

• Kaminsky, FV, Khachatryan, GK, Andreazza, P, Araujo, D, Griffin, WL. 2009.

Superdeep diamonds from kimberlites in the Juina area. Mato Grosso State, Brazil.

Lithos. 112S(2):833-842.

• McCandless, TE, Dummett, HT. 2003.

Some aspects of chromian spinel (chromite) chemistry in relation to diamond exploration. Geological Association of

Canada-Mineralogical Association of Canada Annual Meeting, Vancouver.

• Stephens, WE, Dawson, JB. 1977. 'Statistical comparison between pyroxenes from kimberlites and their associated xenoliths'. Journal of Geology. 85:443-449.

• Viljoen, KS, Dobbe, R, Smit, B, Thomessot, E and Cartigny, P. 2004. Petrology and geochemistry of a diamondiferous lherzolite from Premier diamond mine, South Africa.

Lithos. 77:539-552.

• Williams, CM, Robey, JVA. 1999. 'Petrography and mineral chemistry of the Mwenezi-01 kimberlite, Zimbabwe'. In: Gurney, JJ, Gurney, JL, Pascoe, MD and Richardson, SH (eds.). Proceedings of the VIIth International Kimberlite Conference.

Red Roof Design: Cape Town, 896-903.

IN SID E M IN IN G 1 0 | 2014 25

MINERALS PROCESSING

A change for the better

old barrel screen did not remove the BIF and could not reduce the amount of sand that was reporting to the plant. Though the plant at that time had a bottom cut off of 5 mm, the amount of the sand reporting to the plant resulted in blockages, increasing the viscosity of the pans, thus hindering recovery. Hence, there plant throughput was significantly lower.

Changes in the plant process

The increase in stone recovery – with the change in processing method – at the Brakfontein Hill Complex, Middle Orange River, was certainly the right thing to do, as this case study shows.

By BC Ringane, Rockwell Diamonds

T

HE PLANT specification and design chosen by a mine has a significant impact on the distribution of the diamonds recovered by a producer. It is vital that prior to plant design, the geology of the area is well understood. With specific focus on the alluvial diamonds along the MOR, the percentage of sand lenses within the ore and the percentage of calcrete have shown to be among the key factors any producers should consider prior to plant design.

Brakfontein Hill Complex (BHC), an alluvial diamond mine located in the Northern Cape, constructed the old barrel screen during its inception. However, the plant was not running optimally due to the high percentage of sand which ended up in the product, hindering production and recovery. A decision was made to optimise plant

efficiency. Hence an integrated flow solution (IFS) was constructed. The benefit of the IFS is it reduces the percentage of the sand, increasing the throughput; hence there was an increase in the average stone size. In addition there is a reduction in the heavy mineral such as banded iron formation (BIF), hence improved sizing within the pans. Furthermore, the bottom cut off was increased from 3 to 5 mm, to reduce the sand. With specific focus on the diamonds within the 5 to 10 mm, there has been a 7% increase in the average stone size since the construction of the IFS. BHC faced few processing challenges this included the problem of sand lenses rich gravel. In its inception, the mined used an old barrel screen for screening off the oversize (+75 mm). However, few challenges with the process were encountered. The

RDI is constantly trying to find ways to improve the operational margin, through reducing the dollar per ton for each operation. Rider and Roodt (2003) identified seven components for diamond value management, these includes the process efficiency. Process efficiency refers to the extent to which all liberated diamonds are recovered during the recovery process.

The aim is to recover above 99% of the free diamonds. In an effort to further optimise the plant efficiency, BHC strategic management made a decision to take into consideration additional variables when finding optimal ways to increase the efficiency of the plant, one variable that was found to be vital was the changing geology of the area.

When RDI acquired BHC, mining was mainly focused on the upper terrace. The upper terrace (60 to 90 m above present river bed, A1 and B1 on Figure 1) is generally coarse boulder gravel, with sedimetological characteristics of a high energy environment. The package has upward fining alluvial gravels with sporadic sand lenses capped by a hard calcrete, which protected the gravel erosion. Contrary the lower elevated terraces (less than 30 m above present river bed, C1 on Figure 1) have 30% of sand matrix with a high proportion of sand lenses high proportion of zeolite-rich sand lenses and BIF. The gravel particle sizes ranges mainly from cobble – pebble with occasional boulders. Lower terrace deposits are generally covered by 1 to 4 m of sand.

A schematic plot of the different terraces is shown in Figure 1.

The change in geology resulted in an increase in the amount of sand and clay reporting to the plant. The high sand lenses resulted in a decrease in the throughput thus impacting plant efficiency negatively. The possible causes of reduced efficiency are: • The increased sand throughput affected the rheology of the puddle medium, FIGURE 1 Adapted from G Dorkin (2013) internal report on the regional model

26 INS I DE MI NI NG 1 0 | 2 0 1 4

MINERALS PROCESSING resulting in expulsion of the diamonds with the lighter fractions.

• The increase in the BIF resulted in the increase in the density of the gravel, thus reducing recovery.

• The increase in sand and clay in the gravel matrix, result in masking of the diamonds.

In order to avoid diamond loss during processing, the mine has to reduce the amount of gravel processed. Reducing the amount of gravel processed in an alluvial diamond has a negative impact, this is due to the nature of an alluvial mine and diamonds recovery is strongly dependent on the amount of gravel processed.

The producer had to develop ways to upgrade the concentrations and improve the quality of the gravels sent to the plant. At that time the producer would use a barrel screen, which generally removed material above 75 mm.

This was done through the installation of a 3 m x 8 m front end in-field screen was constructed to ensure that the gravel which often might be sand rich lenses is processed at the required rates to ensure a positive cash flow. The IFS is a barrel-fed, Bivitec absolute non-blind screen from Dabmar Manufacturing, it allowed the screening out of material below 5 mm, and above 55 mm, thus reducing the amount of sand and oversize material reporting to the plant (Figure 2). In addition to reducing the amount of sand and oversize material reporting to the plant, the design of the screening plant allows the removal of significant amount of BIF and other iron rich clasts from the gravel prior to transportation to the processing plant. Through this not plant throughput is increased and efficiency can improve.

The impact of the IFS is clearly observed in Figure 3. The graph shows the scrubber volume processed between April to June of 2010 (blue) and 2012 (red), where 2010 reflects the period prior to the installation of the IFS, and the 2012 data reflects the period after installation. Taking into consideration the fact that there are days where no mining or processing occurred due to public holidays and a maintenance day, a seven-day moving average was applied to smooth out the data.

From the data, it is evident that the installation of the IFS resulted in an increase in volume processed fed into the scrubber. The main function of the scrubber is to wash the material prior to feeding into the pans. Liberation is minimal in the scrubber. On average FIGURE 2 (top) BHC process flow sheet FIGURE 3 (middle) The scrubber feed volume for 2010 and 2012 FIGURE 4 (left) Size frequency distribution for BHC

IN SID E M IN IN G 1 0 | 2014 27

MINERALS PROCESSING FIGURE 5 The grade plot for BHC

distributions have been truncated at 5 mm in order to make the comparison easier.

Moreover, the area of focus will be the size classes below 10 mm. The salient feature observed is that the diamond distribution for the post IFS period is coarser than that of prior to the installation. Post installation of the screen material the average stone size increased slightly by 7%. The increase in the average stone size is contributed mainly to the increase in the number of stones recovered across all sieve classes as efficiency increases. An improvement in grade was also observed.

In summary

increase the volume is observed is above 10%. The benefit of increasing into the scrubber implies that the higher volume of right sized material (the removal of the oversize material, sand and BIF) can be fed into the pans, thus increasing efficiency and feed rate.

Figures 4 and 5 compare the size frequency distribution and the grade-size plot for pre installation of the IFS and post installation. Size distribution is a standard tool to determine if there are any changes in the carat recovery as a result of change in the resource or in the processing. Both

The installation of the IFS has yielded an improvement in volume and carats recovery. The strategy plan has proven to be a vital step in attempting to continue to produce at economic beneficial levels for RDI. It highlights the importance of companies to continually attempt to find better and economical methods to survive in the constantly changing markets.

Industry workhorses

L

IQUID RING vacuum pumps are rotating positive displacement pumps. These pumps are typically used as a vacuum pump but can also be used as a gas compressor. The function of a liquid ring pump is similar to a rotary vane pump.

With a liquid ring pump, the difference is the vanes are an

integral part of the rotor and turn a rotating ring of liquid to form the compression chamber seal. They are an inherently low friction design, with the rotor being the only moving part. Sliding friction is limited to the shaft seals.

Liquid ring pumps are typically powered by an induction motor.

Process Vacuum, suppliers of liquid ring vacuum pumps, has an edge with regard to understanding and supplying

vacuum systems, and having access to the best liquid ring vacuum pump manufacturers in the world. This allows them to provide reliable solutions and to support, especially liquid ring vacuum pumps for filters, one of the most commonly used vacuum filters in the mining industry.

An advantage is the energy efficiency of this technology. It’s the future now!

Recent projects completed include large liquid ring vacuum pumps for horizontal vacuum belt filters with suction capacities of up to 18 000 m3/hr.

Principles of OperaƟon for Liquid Ring Vacuum Pumps

Prior to opera opera o on, n, the pump casingg is filled with sealing liquid. liquid.

28 INS I DE MI NI NG 1 0 | 2 0 1 4

Wh When hen the impellerr rotates, the cen centrifugal ntrifugal force fo forms orms a liquid rin ringg that conforms to the pump’s cas casing. sing. Because of the centrally mo mounted ounted impeller, crescent-shape spaces are formed spa formed.

Gas is induced into the low pressure area (yellow) and discharged from the high pressure area (green).

MINERALS PROCESSING

Mopani Copper installs two more BMR winders FLSmidth 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.

F

OLLOWING ON from the recent and successful installation of a Blair multi-rope (BMR) winder at Glencore’s Mopani Copper Mines’ Synclinorium shaft in Zambia, FLSmidth will now supply BMR winders for the mining company’s two

new shafts – the first at Nkana mine’s Mindola shaft in the Kitwe district and the second at the new Mufulira shaft at Mufulira mine, 25 km due north of Kitwe. This is the highest value order FLSmidth’s mine shaft systems business has received for BMR winders to date.

“With only about 50 BMR winders of this kind operating in the world, it is gratifying to be adding another four in a single application, bringing the number of these units in one country up to five, whereas two years ago

there were none,” says Wendy Norman, FLSmidth’s sales manager for mine shaft systems in South Africa.

FLSmidth will supply identical equipment for both shafts, each of which will incorporate a double-drum BMR rock winder as well as a single-drum BMR man/materials winder. The drums are almost identical for all four winders, each measuring 5.7 m in diameter with two 1.8 m wide rope compartments. Also setting this order apart is the fact that this LEFT AND BELOW One of the BMR winders at the start of the installation process, and the finished product

IN SID E M IN IN G 1 0 | 2014 29

One Source

Many Solutions

FLSmidth is your One Source for crushing, grinding, classifying, thickening, clarifying, slurry handling, ďŹ&#x201A;otation, mine shaft systems, pyroprocessing, material handling, automation, screens, centrifuges and complementary products, engineering, metallurgical testing and modernisation services. FLSmidth offers you a complete line of equipment and services with proven reliability and enhancing performance from the leading brand names of ABON, Buffalo, CEntry, Conveyor Engineering, Dawson Metallurgical Laboratories, Decanter Machine, Dorr-Oliver, EIMCO, ESSA, FFE, Fuller-Traylor, KOCH, Knelson, Krebs, Ludowici, Maag Gear, Mayer, Meshcape, MIE, MĂśller, MVT, PERI, Phillips Kiln Services, Pneumapress, RAHCO, Raptor, Roymec, Shriver, Summit Valley, Technequip and WEMCO. Enjoy increased recoveries while saving time and money on your next project! Let us help you tackle your speciďŹ c requirements.

For more information contact us 4EL NO s mSM ZA mSMIDTH COM s www.ďŹ&#x201A;smidth.com

MINERALS PROCESSING

FLSmidth double-drum BMR winder showing splash screens and brakes

The company will begin delivering the equipment to Mopani Copper Mines in the last quarter of 2015, with installation likely to commence 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.

Once manufacture of the drum shafts is completed, and following a trial assembly in South Africa, the Zambian government will send mining inspectors

will only 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 giant universal coupling used on double-drum BMR winders to link the two drums mechanically, without the use of gears, to allow the drums to be angled towards the conveyance centres to improve rope fleeting angles. This system offers significant capital cost savings over electrically coupled winders.

A one-source solution The cost of a BMR installation is offin the mine shaft set by the higher tonnages that can be hoisted using twin ropes. business worldwide FLSmidth, an industry leader in this technology unique to the Afrito examine and verify all the equipment can mining industry, installed the first before it leaves the country. Thereafter, Hooke’s joint in the early 2000s at a gold the equipment will be dismantled and mine in Westonaria. Development work transported on superlink trucks by road had been in progress since the mid 1980s to Zambia. Owing to their significant on the use of these joints in a hoisting size, the drums will be sent in half secapplication. At the Mindola and Mufulitions. All the equipment necessary for ra shafts, the Hooke’s joint will allow the this installation will be sent to the mine wide BMR drums to be installed at an site in strict sequence, since the main angle of 12 degrees to each other, accomcomponents are too big to be stored modating the drum centres without inon-site for any length of time. The total curring any fleeting angle problems.

weight of the components that will travel to the mine by road is in the region of 3 000 tonnes, including electrical equipment such as transformers.

FLSmidth, the mining industry’s undisputed leader in deep-level hoisting, is focused on building the necessary skills and experience to become a one-source solution in the mine shaft business worldwide, just as it is in the mineral processing and cement industries. This follows a formal integration of the company’s mine shaft systems capabilities in South Africa and Canada in 2012, to form a dedicated business unit within FLSmidth.

The mine shaft systems offering comprises two distinct product lines serving a common and unique sector of the mining industry – mine hoisting and mine shaft equipment technology – and draws on a spectrum of inhouse engineering skills to offer customers a holistic solution. FLSmidth’s global procurement strategy allows the mine shaft systems team to source its equipment from all parts of the world, enabling it to secure the most competitive prices, while still delivering the quality products with which the company has come to be associated.

IN SID E M IN IN G 1 0 | 2014 31

MINERALS PROCESSING

A systems approach to transfer point design A systems approach to bulk solids handling design is essential to ensure operational characteristics are matched throughout a mineral processing plant. So says Mark Baller, managing director of Weba Chute Systems.

T

HE MOST recurrent problems on transfer chutes are spillage, blocked chutes, high levels of wear on the receiving belt due to major differences between the material velocity and the belt velocity, rapid chute wear, degradation of the material being transferred, excessive generation of dust and noise, and misplacement of the receiving conveyor belt due to unbalanced loading from the transfer chute.

Baller explains that conveyors, feeders, crushers, hoppers and screens are typically selected based on specific operational requirements, with little emphasis placed

on the design of the chutes transferring materials between elements. “However, chutes are essential elements in a bulk solids handling plant, and are also subject to operational characteristics and physical constraints.”

The optimisation of chute performance is a process of defining the geometry of the chute to reliably convey material from one point to another. The complexity of chute performance means that chute design should be carried out at the plant design stage, and not added as a conveyance to transfer material from one point to another at a later stage.

“The expertise of chute manufacturers is useful during the design stages of a project to eliminate potential flow and maintenance problems at a later stage,” he adds.

“It is an interesting fact that transfer points can contribute to some of the highest maintenance costs on a mine, and yet many engineers often do not view transfer systems as a critical element of the minerals processing system. Weba Chute Systems believes that transfer points, by the very nature of their application, should be accorded the same level of importance as any other machinery in the minerals processing cycle. If one considers the costs of replacing a conveyor belt, and the downtime associated with maintenance and belt replacement, it would be foolhardy to ignore the implications of neglecting this critical factor,” Baller asserts.

Weba Chute Systems’ extensive experience and technical expertise, coupled with its broad applications knowledge, has positioned it as the leader in its field.

ABOVE A systems approach to bulk solids handling design is essential to ensure operational characteristics are matched throughout the plant LEFT The optimisation of chute performance is a process of defining the geometry of the chute to reliably convey material from one point to another

32 INS I DE MI NI NG 1 0 | 2 0 1 4

MINERALS PROCESSING

Weba Chute Systems believes that transfer points, by the very nature of their application, should be accorded the same level of importance as any other machinery in the minerals processing cycle

The design of systems is undertaken using sophisticated 3D computer software and data received from customers is always verified. In many instances, the highly skilled personnel at Weba Chute Systems

are in a position to make cost-saving recommendations to the customer.

Baller points out that quality manufacture also forms an important part of the process and performance guarantees, set

in accordance with operational and application parameters, are provided with all Weba Chute Systems. Each Weba Chute System is custom designed for the transfer point served and is configured to control the direction, flow and velocity of the calculated volume and type of material processed in a particular application.

“If you considers that the conveyor belt can account for up to 60% of the capital cost of a bulk materials handling plant, the cost implications of constant replacement of a conveyor belt due to wear, can become significantly higher than the original capital investment. By applying an innovative concept such as a Weba Chute System transfer point, you can substantially reduce maintenance expenditure in the minerals processing environment,” Baller concludes.

IN SID E M IN IN G 1 0 | 2014 33

Coralynne & Associates +27 (011) 849 3142

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• • • • • •

Optimum material flow Up to 80% decrease in material degredation Reduced dust and noise levels Virtually maintenance free Greatly reduced spillage Significant reduction in belt damage

Tel: +27 (0) 11 827-9372 Fax: +27 (0) 11 827-6132

w w w . w e b a c h u t e s . c o m

•

w e b a @ m j e n g . c o . z a

MINERALS PROCESSING

Screening terminology

L

IKE ANY mechanical and physical process, there are scientific, industrial and layman terminologies that apply – equally, too, to screening. To assist, Dabmar Manufacturing has put together the following basic list of terms associated with mechanical screening: • Amplitude: This is a measurement of the screen cloth as it vertically peaks to its tallest height and troughs to its lowest point. Measured in multiples of the acceleration constant g (g-force).

• Acceleration: Applied Acceleration to the screen mesh in order to overcome the Van der Waal forces.

• Blinding: When material plugs into the open slots of the screen cloth and inhibits overflowing material from falling through.

• Brushing: This procedure is performed by an operator who uses a brush over the screen cloth to dislodge material from a blinded opening.

• Contamination: This is unwanted material in a given grade. This occurs when there is oversize or fine-size material relative to the cut or grade.

Contamination includes: - Oversize contamination occurs when there is a hole in the screen such that the hole is larger than the mesh size of the screen. Other instances where oversize occurs is material overflow falling into the grade from overhead, or there is the wrong mesh size screen in place.

- Fines contamination is when large

sections of the screen cloth are blinded over, and material flowing over the screen does not fall through. The fines are then retained in the grade.

- Foreign body contamination is unwanted material that differs from the virgin material going over and through the screen. It can be anything ranging from tree twigs, grass and metal slag to other mineral types and composition. This contamination occurs when there is a hole in the scalping screen or a foreign material’s mineralogy or chemical composition differs from the virgin material.

• Deck: A deck is frame or apparatus that holds the screen cloth in place. It also contains the screening drive. It can contain multiple sections as the material travels from the feed end to the discharge end. Multiple decks are screen decks placed in a configuration where there are a series of decks attached vertically and lean at the same angle as the preceding and exceeding decks. Multiple decks are often referred to as single deck, double deck, triple deck, etc.

• Frequency: Measured in hertz or revolutions per minute. Frequency is the number of times the screen cloth sinusoidally peaks and troughs within a second.

As for a gyratory screening motion, it is the number of revolutions the screen or screen deck takes in a time interval.

• Gradation (grading, also called cut or cutting): Given a feed material in an initial state, the material can be defined to a

have a particle size distribution. Grading is removing the maximum size material and minimum size material by way of mesh selection.

• Screen media (screen cloth): It is the material defined by mesh size, which can be made of any type of material such as steel, stainless steel, rubber compounds, polyurethane, brass, etc.

• Shaker: A generic term that refers to the whole assembly of any type of mechanical screening machine.

• Stratification: This phenomenon occurs as vibrations are passed through a bed of material. This causes coarse (larger) material to rise and finer (smaller) material to descend within the bed. The material in contact with screen cloth either falls through a slot, or blinds the slot, or contacts the cloth material and is thrown from the cloth to fall to the next lower level.

• Mesh: This refers to the number of open slots per linear inch. Mesh is arranged in multiple configurations. It can be a square pattern, long-slotted rectangular pattern, circular pattern, or diamond pattern.

• Scalp, scalping: This is the very first cut of the incoming material with the sum of all its grades. Scalping refers to removing the largest particles. This includes enormously large particles relative to the other particles’ sizes. Scalping also cleans the incoming material from foreign body contamination such as twigs, trash, glass, or other unwanted oversize material.

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ing ind s l B n Non olutio e t S u ol ng A b s re e n i c S

DABMAR MANU FA CTUR IN G

COMPANY (PTY) LTD Please contact jm@dabmar.co.za or c +27 (0)82 449 5919

www. ww ww. dabmar .co. ww .co.za co za

MINERALS PROCESSING

Old but still effective Water processing in SA’s mining industry is to receive a beneficial boost with continuous ION filtration (CIF). This technology has been around for 50 years but is still impressive.

P

LANNED FOR A phased rollout during 2014, CIF is a significant coup for Multotec. The team is excited about the prospects for the treatment of mine wastewater and AMD. By applying the CIF technology to the mining industry, we will be able to contribute to the drive to preserve our valuable water resources,” says CJ Liebenberg, environmental process engineer at Multotec.

CIF is based on ion exchange (IX), a technology that has been on the market for over 50 years; it also resembles continuous sand filtration with the salient differences being that CIF uses charged

IX resin beads instead of sand as its filtration medium, and it ‘filters’ dissolved solids out of the solution, in addition to suspended solids. This feature of CIF distinguishes it from its competitors in the conventional IX market as it allows for the elimination of a pretreatment stage to remove solids.

Each CIF module comprises a series of columns, each designed for a specific function – ionic filtration, resin washing (pre-elution wash), resin regeneration and resin rinsing (post-elution wash).

Resin moves as a packed bed in the columns, continuously being transferred from the bottom of each stage to the

next. Counter-current operation ensures optimum mass transfer and continual high contaminant removal.

Liebenberg explains that the CIF technology complements the other products and services in Multotec’s portfolio. “Multotec’s core business is the supply of products and services to the mining and mineral beneficiation industries, including solid/liquid separation equipment such as

A Clean TeQ operated CIF plant treating 0.6 MLD of borehole water containing approximately 8 000 mg/ℓ TDS, 100 mg/ℓ calcium, 400 mg/ℓ magnesium and 1 000 mg/ℓ bicarbonate

IN SID E M IN IN G 1 0 | 2014 35

MINERALS PROCESSING

A mobile DeSALx plant, with a capacity of 0.5 MLD, was used on CSG to produce agricultural-grade product water for livestock and crops. The feed and product water total dissolved solids were 4 500 mg/ℓ and 1 650 mg/ℓ, respectively, with over 90% water recovery. The process consumed less than 0.5 kW/m3

centrifuges and filter presses. Our aim is to assist in the alleviation of water shortage issues and to encourage sustainable

development in South Africa. Mining is often regarded as being a non-sustainable enterprise from an environmental perspective and we would therefore like to become part of the solution, rather than the perceived problem.”

He continues that treatment of mine water and AMD, with containerised systems, is considered to be niche markets for CIF. The CIF process is similar, in some respects, to the GypCIX process that was considered by the International Network for Acid Prevention for the treatment of AMD. CIF differs in a few respects. These include that lower flow rate requirements in CIF allow for a much smaller clarifier than would be required in Gyp-CIX. This attribute is the result of regeneration columns being continuously agitated, eliminating the need for a high flow rate to keep resin and formed gypsum in suspension. Flow rate, in turn, impacts on the power requirements of the process with CIF requiring less power due to its lower flow rate requirements. These

factors result in lower operating and capital requirements than Gyp-CIX. Liebenberg points out that CIF technology has had significant success in the treatment of coal seam gas (CSG) associated water in Australia. There are indications that such activities might take place in Southern Africa in the near future, and this will therefore be a significant market for CIF. Although the cost of a CIF system is application specific, it tends to be superior to other technologies on the market, especially reverse osmosis, both with respect to capex and opex. In fact, depending on the CIF product selected – CIF single stage, DeSALx or HiROx – it can be up to 50% more cost-effective than conventional technologies. This is primarily due to its simplicity, use of low-cost regeneration chemicals and low power requirements.

Zero to minimal pretreatment is generally required, especially because the system can operate in the presence of up to 40% solids by weight.

Additional to the benefits of CIF mentioned previously are that water recoveries exceeding 95% are achievable. The fact that it is fully automated enables the system to operate independently and to be controlled remotely. Due to its simplicity it is easily operated and maintained, eliminating the need for highly skilled labour.

Access to remote locations is allowed for as the containerised systems are mobile.

Finally, potentially valuable by-products like gypsum can be produced in a saleable form using CIF.

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MILLING & CLASSIFICATION IS OUR BUSINESS E V E N 1 0 0 Y E A R S O F B E I N G A N I N N O V AT O R A N D

FROM INVENTING BETTER SOLUTIONS

EVERY DAY

Are you looking for cost-effective size-reduction and classification of ores, industrial minerals and concentrates?

Contact Loesche SA to find out the advantages of the Loesche Grinding System for your beneficiation process.

Tel: +27 (0)11 482 2933 | Fax: +27 (0)11 482 2940 | Email: umeyer@loeschesa.co.za | Web: www.loesche.com

Loesche six roller Mill

MARKET LEADER DOES NOT KEEP US

JUNIOR MINING

Predictive discovery Gold fever permeates Burkino Faso. It’s everywhere, and once-primitive greenfield methods of mining are fast turning into properly structured and equipped mining operations.

T

HE BONSIEGA Permit Group covers nine exploration permits totalling 1045 km2 in area, with approximately 100 km of strike length in the same greenstone belt that hosts the Samira Hill Gold Mine in Niger.

A tenth permit, Bassieri, which covers an additional 74 km2, is close to being granted. Most of the permits contain artisanal workings and/or significant gold geochemical anomalies.

The Bonsiega permits were acquired either by direct application in PDI’s name or through separate agreements with third parties. The company holds 100% ownership of the core permits which carry almost all of the known, drilled gold mineralisation. It is also earning either 95% or 100% of three peripheral permits.

In earlier exploration, PDI discovered a series of gold geochemical anomalies, some of which were tested with large reverse circulation (RC) drilling programs. A series of prospects were discovered containing ore grade and width gold intercepts. These included Bongou, Dave, Fouli, Laterite Hill, Tamboana and Prospect 71, all of which are 100% owned by PDI. In 2012/13, PDI focused most of its attention on the higher-grade prospects, especially Bongou. Several other areas were also tested during the field season with RC drilling, bedrock sampling and/or ground geophysics, in order to enlarge the prospect pipeline.

Burkina Faso (Figure 1). It covers artisanal workings in the form of an irregular open pit approximately 150 m long and 50 m wide. Gold mineralisation is contained within an intensely silicified, quartz-veined and pyritic microgranite intrusion (Figure 2).

Earlier exploration by PDI included rock chip sampling, trenching and one RC drill

hole in 2011/12, which intersected 54 m at 2.1 g/t Au from 36 m, including 20 m at 4.8 g/t Au. A large programme of exploration aimed at following up this result commenced on the Bongou Prospect in November 2012, and consisted of RC drilling, ground geophysical surveys, bedrock drilling using a power auger, soil sampling, trenching and geological mapping.

Bongou Prospect The Bongou Prospect is located within the Laterite Hill Gold Field in Eastern FIGURE 1 (top right) Geology of the Laterite Hill Gold Field showing prospect locations FIGURE 2 (right) Silicified, quartz-veined, gold-mineralised microgranite in contact with foliated gabbro or mafic volcanics in Bongou opencast mine. Mr Seye Kote, PDI’s Chief Geologist in Burkina Faso, in the foreground

IN SID E M IN IN G 1 0 | 2014 37

JUNIOR MINING

FIGURE 3a and b (above) Bongou cross sections – (a) Left – through RC drill hole BNGRC010, (b) Right – through RC drill holes BNGRC002 and BNGRC014. No vertical exaggeration. See Figure 4 for drill hole locations FIGURE 4 (left) Plan view of Bongou Prospect drilling FIGURE 5 (bottom left) Power auger gold geochemistry contour plan. Note size of Bongou gold mineralised zone for comparison with size of the discovered gold anomalies. Power auger samples were collected at the interface between the overlying cover and the weathered bedrock and analysed for gold by AAS at SGS in Ouagadougou

grades located close to its northern contact with gabbro (Figures 3a and 3b). At a 3 g/t Au cut-off, there are now four high-grade intercepts, all located in this near-contact position, and apparently correlating with each other: • BNGRC010: 16 m at 9.7 g/t Au • BNGRC014: 16 m at 8.9 g/t Au • BNGRC004: 7 m at 10.1 g/t Au • BNGRC001: 6 m at 11.8 g/t Au Lower-grade gold mineralisation with an average grade of approximately 1 g/t Au is located adjacent to, and to the south of, the high-grade zone. The total true width of the gold mineralised zone is up to 50 m.

Bongou regional exploration

Bongou RC drilling RC drilling in 2011/12 produced a series of excellent gold intercepts, including: • BNGRC010: 48 m at 4.3 g/t Au from 34 m • BNGRC014: 26 m at 6.9 g/t Au from 111 m

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• BNGRC004: 47 m BNGRC004 10 m 10 att 7.4 g/t 7 4 /t Au A from f 47 • BNGRC003: 102 m at 1.1 g/t Au from 4 m • BNGRC002: 70 m at 1.2 g/t Au from 62 m (stopped in mineralisation) Nearly all of the gold mineralisation consists of altered microgranite, with higher

PDI’s programme of geological mapping, ground geophysics and power auger geochemical sampling generated a new target, approximately 400 m north-west of the Bongou artisanal workings, with a peak value of 4.8 g/t Au. The anomaly covers a larger area than the Bongou mineralised zone and remains untested by drilling (Figure 5).

Testing of two other targets along the major Bongou Fault Zone (Figure 6) is

JUNIOR MINING

FIGURE 6 (left) Regional geological map of the area near Bongou showing location of two target zones (red dashed line ellipses), 4 km and 10 km north-east of the Bongou artisanal workings

largely incomplete because of the presence of thick, wet alluvium. Rotary air-blast testing of these targets will be required in the next field season.

Metallurgical test work – Bongou A programme of preliminary metallurgical test work was carried out with the aim of

providing an indication of potential gold recovery by standard CIL treatment. One sample, weighing 20 kg, obtained from seven RC drill holes was submitted for metallurgical test work. The test work was carried out at SGS’s Perth laboratories under the supervision of Coffey Mining. A mineralogical study was also carried out by

Roger Townend and Associates. All of the sampled intervals in the Bongou composite sample were of primary (not oxidised) mineralisation. A 500 g screen fire assay of the composite sample at SGS in Perth gave a head grade of 2.92 g/t Au and a multi-element ICP analysis indicated low levels of potentially deleterious elements (e.g. arsenic and antimony).

The sample was ground to 75 microns and subjected to a standard cyanide leach test over 72 hours. Gold recovery was 94% at the end of the test with 90% recovered in the first four hours (Figure 7). Cyanide and lime consumption were 2.0 kg/t and 0.3 kg/t respectively. Cyanide consumption was not optimised and is expected to decrease considerably in future testing when oxygen levels are increased to the levels expected in a commercial CIP plant.

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DRILLING & BLASTING

Undersea mining Sandvik has designed and built the cutting drum for their bulk cutter (BC), which is the first seafloor production tool and an important step closer to making seafloor mining a reality.

C

ANADA-BASED Nautilus Minerals has been granted the first mining lease for polymetallic seafloor massive sulfide deposits in the territorial waters of Papua New Guinea, where it intends to produce copper, gold and silver. The company has completed its first seafloor production tool (SPT), a high-productivity machine responsible for the bulk of the production.

The machine’s cutting drum was designed and built by Sandvik and its design is similar to those used on large continuous miner machines.

The BC is the first, and heaviest, of the three SPTs to be assembled, weighing 310 tonnes when fully assembled. It is designed to be a high productivity machine responsible for the bulk of production.

Nautilus’ CEO, Mike Johnston says “This is a major milestone for the company, having the first of the three SPTs assembled.

This achievement brings the company all the closer to making seafloor mining a reality.”

Subsea vehicle designer and manufacturer, Soil Machine Dynamics (SMD) of Newcastle-upon-Tyne, UK, is the company responsible for building the SPTs for Nautilus. SMD are experts in the “marinization” of mechanical, hydraulic, electric

and electronic equipment for use in a subsea environment (water and pressure immersion). SMD uses this skill set as the basis of much of its existing product line in remotely operated vehicles and subsea trenchers. Nautilus is proud to be able to utilize their vast experience in the design, manufacture and testing of our SPTs. The BC is the heaviest of the three SPTs, weighing 310 tonnes when fully assembled. It is designed to be the high productivity machine responsible for the bulk of production.

Some world class companies have been involved in the design of the SPTs: • The cutting drum of the BC was designed and built by Sandvik (Austria), a world leader in hard-rock mechanized mining and rock cutting equipment. The designs are based on similar designs used on large continuous miner machines used in underground mining and construction • The track sets for all three SPTs have been designed and built by Caterpillar, based on an existing Caterpillar excavator track design. Modification to the track set for subsea operation and required cutting duty was completed by SMD in consultation with Caterpillar and Sandvik • The dredge pumps for all three SPTs have been supplied by Damen, one

of the world’s leading dredge equipment suppliers and are based on existing catalogue designs used in the dredging industry • The hydraulic equipment for all three SPTs is based on existing off-the-shelf Bosch Rexroth hydraulic equipment, with adaptations by SMD • The flexible hoses for all three SPTs have been designed and supplied by ContiTech AG (Germany) and are very similar to the rubber hoses used in the dredging industry Companies and institutions involved in the simulations and test work of the BC include CSIRO, Cellula Robotics, Deltares, Istanbul Technical University, ContiTech Oil and Marine Corp as well as Paterson and Cooke Consulting.

“We are proud to have such world-class companies and institutions involved in the design and testing of these tools. The next step is to carry out commissioning and acceptance testing of the BC in parallel with assembling the other two production tools, the auxiliary cutter and the collecting machine,” Johnston says.

How they will work The excavation and collection has been split into three individual tasks which will each be carried out by a different vehicle. The auxiliary cutter is designed as the pioneering machine which prepares the rugged sea bed for the more powerful bulk cutter. These two machines gather the excavated material; the third vehicle, the collecting machine will collect the cut material by drawing it in as seawater slurry with internal pumps and pushing it thought a flexible pipe to the subsea pump and on to the production ship via a riser system.

Sandvick’s new undersea drum and bulk cutter

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DRILLING & BLASTING

Licence to drill Blasting B lasting is is very very dangerous. dangerous. A skilled skilled master master blaster blaster is is deliberate, deliberate, m methodical ethodical and and patient. Being adept at drilling for blasting, Blue Chip Mining has honed these skills to a fine art.

F

ROM ITS ORIGINAL conception, rather than chasing the fast buck, Blue Chip Mining spent 18 months training staff, sourcing equipment, carrying out quality control testing and generally polishing its services and products. Trading only began when the company was absolutely sure it would deliver the best possible service to its customers.

Now, thanks to that initial investment, the company is now one of the most reputable and flourishing drilling and mining companies in Africa, with big company contracts such as Anglo American. Managing director Martyn van Zyl says, “Efficiency is a major part of our focus, ensuring that we save clients costs and become really competitive in the tendering process.”

Explosive impact Blue Chip Mining has its own blasting licence, as registered with the South African Police Service. This allows the company to handle explosives, perform blasting and complete processing to the final product before it goes to the smelt pits for refinement. Its entire fleet has also been

equipped with mobile mining equipment, while also changing its workshop to a mechanical operation, allowing employees to use equipment they are familiar with in every location.

Safety is at the forefront of the company’s priorities and all equipment meets the country’s robust standards, resulting in exemplary working conditions and a record of safety that is second to none.

“We do a comparative analysis of parts and products, testing vigorously before we promote them to clients, or include them in our operations,” adds Van Zyl. With further efficiency targets on the horizon, the company will stop at nothing to ensure cutting-edge practices and is currently testing the lifespan of drill bits, to determine the most abrasive metals. The outcome shows exactly what is required for better penetration and how many metres can be mined every minute.

Van Zyl explained how the reputation of the company came above everything else.

“We don’t want to engage in practices that can cause damage to the company, so ethics are a high currency in our organisation,” he says. “It is essential that we also subscribe to the policies of our biggest

Precision drilling for greater effect

clients because they are constantly under the microscope.”

Commitment to the future The current economic downturn, while proving a big challenge, is overcome with careful planning, regular consultations among staff and using profits to improve maintenance. This meticulous approach, which has always proved so beneficial, even before the recession, meant that the company and its 300-strong workforce avoided any long-term problems.

The practice of forging good professional relationships, formed in a competitive industry, will ensure optimum trading for the company over the next 20 to 50 years. In recent years – particularly since the turn of the new millennium – there has also been a noticeable increase in the demand for South African expertise in civil engineering and mining.

With seven years of faultless operations, industry integrity ingrained in its philosophy, and a position at the summit of its field, the company has every reason to keep chipping away.

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DRILLING & BLASTING

New rock drill is a leap ahead

With technology, innovation is mandatory.

This is especially true in mining, because it translates into productivity increases and greater operating efficiencies, which in turn translates into increased profits.

LEFT User-centric design is at the core of the HRD-system

Drill features

T

HE NEW hydraulic underground hand-held rock drill-system (HRD100) from Atlas Copco is one of the most powerful underground hand-held rock drills on the market today. The system consists of the rock drill (RD100), the power pack (PP100) and a selection of water pusher legs. All hoses and cables are included.

In a nutshell, the crucial benefit of the HRD100 is its outstanding drill rate and considerable energy efficiency compared to conventional pneumatic or electrical rock drills. Measured noise is approximately 50% lower than that of a pneumatic drill. The polyurethane cover shields noise and makes the unit shockproof. The unit can handle a drop of two metres.

It features a five-step water adjustment to help the operator use the right amount of water for each step, when the drilling stops, the flow stops automatically.

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“We really made an effort to provide high drill rates at low operational cost. It is equally important to create a system that saves the operators energy by being light and reliable,” says Oleg Korobotchkine, the product line manager.

The stackable PP100 power pack basically manages itself. It monitors all vital functions and can compensate for pressure changes automatically. Smart functions monitor oil flow and oil temperature.

Water-cooling and automatic overheat protection means safety and reliability are at its core. The system also monitors oil volume and compensates for pressure differences. This allows you to work with the PP100 at a 45° angle, without power loss. Simple tools make it easy to top up hydraulic oil in the mine. Working underground is hard work, but thanks to one-handed operation and carrying handles, the HRD-system is making it easier.

• Energy efficiency: Input electrical power to drilling power in drill steel, including rotation -37% • Drill rate: In rock where equivalent drill rate for present pneumatic rock drills are 500 mm/min at 5 bar - > 800 mm/ min. In deep mining, in hard rock, using a drill bit diameter of 34 mm, the HRD100 is four times more productive than pneumatic drills and four and a half times that of electric drills • Drill depth: With a maximum hole diameter of 42 mm, drill bit > 2 400 mm • Hydraulic hoses: Between power pack and rock drill – 10 to 30 m single way.

Colour coded for correct connections • Electrical cable: Between mains supply and power pack, 20 to 100 m • Ambient temperature: +5°C to +40°C • Rock conditions: Possible to drill in all rock conditions, from soft rock ~ 100 MPa (typical in South African platinum mines) to hard rock ~ 250 MPa (typical in South African gold mines) • Drill direction: Able to drill in all directions, horizontal as well as vertical • Torque: 10 to 25 Nm. The HRD100 is fitted with a torque limiter for operator safety • Rotation: Adjustable 150 to 200 rpm.

Built-in exchangeable valve to optimise drill rate at different rock conditions • Vibration level: 11 m/s2 (three-axes ISO 5349-2) • Sound power: 111 dB(A). The10 dB(A) reduction in noise compared to a pneumatic drill is perceived as a 50% reduction to the human ear. Whereas sound pressure is equal to 100 dB(A)

DRILLING & BLASTING

FOUR ACTIONS FOR SUCCESSFUL DRILLING

ACTION 1: Percussive impact

ACTION 2: Feed force

ACTION 3: RotaƟon

ACTION 4: Flushing

Percussive drilling breaks the rock by hammering impacts transferred from the rock drill to the drill bit at the bo om of the hole.

The purpose of the feed force is to keep the drill bit in close contact against the rock. The engineering challenge is to combine high feed force with good rota on.

Rota on moves the drill bit to a new posi on to make the next blow as effec ve as possible. When the drilling starts you need even and smooth rota on.

Drill systems with a high output need good flushing technology to be able to remove drill cu ngs. Par cle size, shape and material affect the flushing methods.

• Water consumption: < 12 ℓ/min • Weight: 23 kg w/o tail hoses, 25.8 kg with 1.2 m tail hoses • Soft start: Includes soft start (for easy collaring) • Water shut on/off: automatic, no drilling or no water flushing. Ability to adjust water flushing amount (five positions) at drilling. Ability to have full water flushing when not drilling by manually opening of flushing port. To be used if drill is jammed in the rock • Operation and handling: one-hand operation controls (power and pusher leg) for operator safety, with front and top handles to be able to hold the rock drill firmly and for easier handling • Pusher leg: Powered by water with single point stainless steel connection to rock drill. Water pressure controlled by the power pack using a built-in pressure regulator

Power pack features

idle mode. It has an automatic standby mode timer. For protection against electrical shock three basic functions are used: - standard over-current protection - protective bonding of relevant exposed conductive parts where the continuity of the earth conductor is monitored - protection by automatic disconnection of the supply if an insulation fault is detected between live parts and earth • Output hydraulic power: ~ 7.5 kW • Output oil flow: ~ 38 ℓ/min • Output hydraulic pressure: ~ 120 bar • Max water inlet pressure: 15 bar • Cooling: Automatic cooling control to ensure max oil temperature of 55°C

ABOVE The four actions for succesful drilling

• Electric cable: Cable includes pilot wire and ground supervision. Earthed copper screen (shielded) • Electronic monitoring and signal for service: Oil volume in tank. Oil and motor temperature, power reduction and finally shut off if too high. Voltage level of the power supply • Handling: Robust frame design with shock absorbers to protect functional parts TheHRD100 system is designed to let you work; fast, and at a low cost per metre drilled. It enables you to focus on the rock, and it will keep you productive, no matter the rock type. As Oleg Korobotchkine puts it, “With this system, you’re ready to rock ‘n’ roll. You do the rock, we do the roll.”

• Physical size: A compact 380 x 695 x 353 mm.

• Weight: 45 kg • Power supply: Three-phase, 525 V ± 10%, 50 Hz 370 to 470 V with reduced performance -25%. With emergency stop and power on demand there is a reduction in motor rpm while in RIGHT The HRD system consists of the rock drill RD100, the power pack PP100 and a selection of water pusher legs

IN SID E M IN IN G 1 0 | 2014 43

DRILLING & BLASTING

Fractum, a

megalodon

rock breaker

Opencast mining and quarrying often produces sizeable problems as a result of activities. Dealing with these problems – massive boulders, in particular – needs a special solution. We take a look at the latest rock breaker.

T

HE WEAR AND tear of traditional mining and quarrying equipment tends to be high.

This is particularly true when chisel-operated hammers are being used.

The chisel, which penetrates hard rock materials, causes excessive vibrations, which are transferred back to the excavator. This makes the excavator vulnerable to damage and shortens its lifetime.

Due to the traditional chisel-based system’s technique of penetrating the material, the wear on the chisel is considerable as well. This is especially the case when rock contains a high amount of abrasive substance. Further, the chisel-based systems produce a high amount of fly rock that not only results in material damage, but is also a serious safety risk.

Now there is another, better solution.

Fractum’s impact breakers work with gravity, a principle that minimises the excavator’s vibration to an absolute minimum. This dramatically extends the service life of breakers, which do not penetrate the material, and saves money on maintenance and repairs. Eliminating the penetration of material provides a long

44 INS I DE MI NI NG 1 0 | 2 0 1 4

service life of the hammer tip as well. Due to the design of the Fractum breaker, the amount of fly rock is minimised, which enhances safety.

While mining and quarrying companies are usually confined to closely spaced blasting patterns to break rock into pieces small enough to fit into crushers, large boulders are often left behind. Fractum has developed breakers that make it possible to deal with oversized rocks straight away. Due to the design and use of technology, machines equipped with Fractum breakers won’t hold up the works. Their solutions have the capability to quickly and efficiently break massive boulders, of over 150 tonnes. Where quarries usually pile up and store large boulders, to break them at a later stage using secondary blasting or traditional chisel-based equipment, companies using Fractum breakers no longer need secondary processes to deal with large boulders. This saves time and money, and increases productivity and safety on-site.

A Fractum impact breaker combined with a quick coupler enables a single operator to handle any stockpile of large

No rock too big for this huge rock breaker

boulders straight away. As a result of this technology, just one operator can easily switch from the breaking function to the grapple. This improves cost-effectiveness and productivity.

These rock breakers have the reputation of being effective, efficient and precise.

Their high-capacity solutions have an impact power ranging from 80 000 J to 300 000 J. This allows for the fragmentation of the hardest rock material in just a few strokes. The design also works in such a way that the operator can work with precision to avoid fly rock. This helps mine and quarry managers to significantly increase breaking capacity on-site while operating alongside other machines.

Avoiding the danger of fly rock makes the Fractum breaker much safer to use than the chisel-operated system or the drop ball. This increases safety in the work environment for the workers and decreases material damage to windows and equipment in general.

The Fractum impact breaker is definitely an all-round useful machine.

MINE SAFETY

3D laser technology improves safety Anglo American Platinum (Amplats) is the world’s leading primary producer of platinum group metals and accounts for approximately 40% of the world’s newly mined platinum.

T

HE COMPANY’S mining operations consist of managed mines, joint-venture mines and associate mines across South Africa and in Zimbabwe. These mines extract ore from the Merensky and UG2 reefs, the Platreef and the Main Sulphide Zone.

The ore is processed by Amplats managed, joint-venture and associate concentrators, and further processed by the company’s smelters and refineries.

FIGURE 1 The typical open design BELOW Mogolokwena Platinum Mine Picture by Jackie Gauntlett

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MINE SAFETY

The Riegl LPM-2K laser scanner

Safety is a primary concern for the company, especially in opencast mining. With this type of mining, good, as in optimal, pit design is crucial. Benches are normally excavated between 2 to 15 m in height, in stacks of three or four, between which a crest is placed for the haul road. The more benches in a stack, the greater the road gradient. Benches have a steeper face angle, approximately 35 degrees, while the stack and overall slope angle is approximately 45 degrees.

This is to prevent slope failures.

From an analysis of the overall slope geometry, as a rule, as steep a slope as possible should be mined in order to reduce the overall stripping ratio. This rule, however, is limited by the haul road’s maximum gradient, which is typically between eight and ten degrees.

This requires more frequent and wider crests, and the need to have flatter slope angles in places to provide slope stability. Slope failure can be disastrous, even catastrophic, particularly in ultra-deep opencast mines a kilometre or more deep. In designing the slope, slope angle, slope height and the horizontal-to-vertical in situ stress ratio are some of the factors taken into account, as are the characteristics of the earth being mined and groundwater.

“Traditionally, we have used conventional survey methods to monitor slope stability of open-pit slopes. This limited the size and number of locations we could survey and the frequency of survey,” says Frans Benadé, section surveyor. “The combination of highly accurate laser scanning units and software specifically engineered for this application enables us to cover a larger area at more frequent intervals.”

Amplats is currently operating two Riegl LPM-2K laser scanners. These units are specifically designed for the automatic and manual long-range profiling of surfaces, operating at distances up to 2 500 m, with an accuracy of 50 mm. The systems perform continuous, 24/7, remote scanning at locations determined by Amplats’ Geotechnical Rock Engineering team collecting hundreds of point measurements daily. The point cloud data collected by the laser scanners is automatically analysed using complimentary software supplied by 3D Laser Mapping. By comparing readings against base measurements, the software can detect surface movement or slope deformations.

“3D Laser Mapping has delivered a safe, accurate yet easy to use solution,” continues Benadé. “This has significantly reduced the risk of injury to personnel, property and equipment, and enabled higher production with increased uptime. It has also reduced the number of resources required for ongoing safety monitoring.”

NEW FACES, NEW SKILLS Colin Thomson has joined 3D Laser Mapping as technical director for mining and monitoring, from September 2014. He will take responsibility for the technical strategy for the mining and monitoring activities of the UK-based supplier of laser scanning hardware and software.

Colin has significant experience working in the geomatics and monitoring sector in Southern Africa.

He spent 15 years surveying in various disciplines after qualification as an engineering surveyor and 15 years as a product manager for mining and monitoring systems. For the past seven years, he has operated Proudafrique, a company specialising in slope stability monitoring systems for mining. This business will be transferred to 3D Laser Mapping.

Muele Radzilani, Proudafrique’s geotechnical support engineer, joins 3D Laser Mapping alongside Colin. She graduated in 2010 with a degree in engineering geology from the University of KwaZulu-Natal.

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MINE SAFETY

Training for safer mines Effective training that engages all levels of employees on a mine and quarry, and positively influences their attitude towards mine health and safety, is important to reduce accidents and maintain healthier workforces.

S

O SAYS Nico Pienaar, director of the Aggregate and Sand Producers Association of Southern Africa (ASPASA), encouraging quarry owners to find ways of training staff in a manner that makes them want to be part of broader initiatives to reduce health- and safety-related incidents both at company level, as well as on an industry wide level.

While standard-type training in the form of lectures and video are Heavy-duty jaw crusher

commonplace on our industry, more effort should be made to identify ways of actually engaging workforces across different cultures and inspiring them to implement what they are learning into their own routines and workplaces.

Poor learning retention “It is important to note that only about 10% of what is learned on a normal training course is retained (and applied) by people once they return to their workplace. In the context of health and safety, this is an unacceptably low percentage, as

every single aspect of this type of training should be applied in order to make a difference in the workplace.

“This clearly indicates that the type of training offered to workers should therefore not be standard and needs to appeal to people on an individual basis in order to provide them with a deeper understanding of topics and how it relates to themselves and their colleagues in the workplace.

“Health and safety training therefore needs to be developed to encourage individual participation, provide practical examples and appeal to individuals’ sense of responsibility in order to ensure better retention of learned material.

“They should be able to visualise what they are being taught and be given practical ways of applying it to their own workspace to make it effective. They should also feel empowered to apply whatever they

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MINE SAFETY

“Post-training follow-ups are therefore an essential part of any training programme and should be checked by those responsible.” Nico Pienaar, director, ASPASA have learned to their own situations and should be given examples of how they can do so, e.g. the importance of maintaining a neat environment and then be given real-life examples of how to organise their workspace and provide safe convenient, storage for their tools etc,” says Pienaar.

Paint a picture He adds that scenarios need to be provided that relate directly to the workers so that they can apply their own life experiences and identify behaviours that they have applied in the past. Once back at the workplace, they should be required to practice what they have learned in a positive and supportive way, which will help

with the retention of learned material.

Post-training follow-ups are therefore an essential part of any training programme and should be checked by those responsible for the initial training, as well as encouraged by line managers and driven by senior management as a custodian of the safety and health of workers. “Everyone should take part and even senior managers should be seen to actively participate and be part of the company’s drive to improve health and safety.”

Managers can assist by: • helping employees understand the broader concepts of health and safety training • recognising employees’ efforts and praising their successes

• behaving as role models • identifying success stories and presenting them as role models.

In this way, workers are constantly encouraged to use what they have been taught and are more likely to foster and embrace a culture of health and safety.

ASPASA and its members are leaders in the implementation of health and safety initiatives within the sand and aggregate mining industry. The association provides members with guidelines and undertakes regular audits of members’ sites in order to ensure compliance with legal and statutory requirements.

In addition, the association seeks to actively support training initiatives in order to reduce health- and safety-related instances on mines to acceptable levels. “We encourage active training programmes on our sites and provide regular information and best practices whenever they become available, so that we can work towards the industry’s goal of zero fatalities and zero harm by 2020,” concludes Pienaar.

Coralynne & Associates +27 (011) 849 3142

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We deliver a SMART lift!

Tel: +27 11 455 9222 or 0860 CRANES | www.jch.co.za

MINE SAFETY

Thwarting danger Like all things in mining, science is involved. When applied, this improves efficiencies, reduces costs and increases profits. All operations are made possible through people – people who need to be safe in a dangerous environment.

N

EITHER EXCITING nor romantic, gratings, stair treads, pressed floors and safety handrails are, nonetheless, critical items in the array of proactive measures to prevent injury and even death on a mine. Without argument, these elements are very necessary precautions and, yet, as with many people, these safety measures are regarded as irritatingly necessary, especially from a cost perspective.

However, the good news is that, in addition to steel products, there are extremely effective, corrosion-resistant alternatives that will make even the accountant happy.

“At Electra Mining, we had an amazing display of our products on show,” says Dodds Pringle, MD of Vital Engineering, South Africa’s well-known local manufacturer of gratings, stair treads, pressed floors and safety handrails.

“We now manufacture and supply reinforced glass fibre gratings, which are low-maintenance moulded fibreglass gratings that are particularly suitable for harsh, corrosive environments and where theft of steel is a concern.

For Pringle, Electra Mining was an invaluable opportunity for existing and new clients to experience first-hand the material benefits of the company’s product range.

“To see, as well to experience the touch and feel of our products, is a powerful introduction to what we do. In many cases, potential customers were not aware of the range of innovative products available, which go far above and beyond the stereotyped ideas that many have of gratings, stair treads, pressed floors and safety handrails. Our products offer many benefits, including lower maintenance cycle times, quicker installation, real cost savings and higher performance options, among other compelling features,” says Pringle.

“As leaders in our industry, our client base has come to expect constant developments and innovative solutions from our company and happily, this year, we exceeded those expectations. We had an array of new products and materials RIGHT Walkway gratings BELOW The reinforced fibreglass version of a grating

In addition to steel products, there are extremely effective, corrosion-resistant alternatives that will make even the accountant happy

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MINE SAFETY

that, without concession, do not compromise safety or quality. In addition, these products are designed to be cost effective, which gives you the best of all these parameters, all in one combined offering.

“Electra Mining Africa, the largest exhibition of its kind in the Southern Hemisphere, offered us a wealth of opportunities to interact with our clients. It was a vitally important opportunity to meet and greet people, as well as to consolidate existing relationships and develop new ones,” Pringle notes. “The value of such an opportunity is hugely significant.”

The demand for quality, hardwearing and versatile materials that deliver optimum safety, particularly in the mining sector, is the driver behind Vital

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Handrails are crucial to safety

Engineering’s range of products. These products are manufactured using a variety of materials, including galvanised steel, stainless steel, aluminium and reinforced fibreglass, depending on cost and corrosion factors.

“We ran a number of live demonstrations at regular intervals during Electra Mining to practically illustrate how significant savings can be made through informed decisions. In support of these demonstrations, we showcased our updated technical information as well as video presentations on numerous aspects of our product offerings.

“In pursuance of flexibility and meeting customer needs, we have been able to deliver creative solutions using materials and finishes that suit those needs. At the same time, we have delivered increased performance and cost savings, which they have now experienced first-hand,” says Pringle.

The bottom line is that an injury or a life lost is, to a business, a loss of productivity, and it’s something we can all avoid.

TECHNOLOGY

Lighting up Hotazel It’s a play on words but, in this instance, it works both ways – lights make many hands work and many hands make light work.

T

HERE ARE occasions when cash flow management demands that sub-projects be completed in as short a time frame as possible. Project dependencies, by virtue of their sequencing and sign-off, determine the timeous implementation of production operations.

Building operational infrastructure for a manganese mining project located outside Hotazel is such an example. Northern Cape mining contractor, Rock Lefatshe Mining Services, finding itself in this situation, resolved its time pressure problems by investing in fleet of mobile lighting systems to light up the night. As a result, productivity and throughput accelerated dramatically.

Rock Lefatshe’s role in the overall project, while not as glamorous as other tasks, is no less important – it is, in fact, fundamental. Using a mobile jaw crusher, the company crushes waste rock to provide sub-base material for the construction of the mine’s haul roads and rail network.

The purchase of the six nine-metre-high VT1-9 TowerLight mobile lighting systems has proved to be an excellent decision. The lights have transformed production, turning it into an efficient, yet safe all-round, 24/7 operation that has not only impressed mine management but has spurred Rock Lefatshe’s own growth ambitions.

Nicolan Govender, sales manager at Pilot Crushtec, who supplied the lighting system, says: “These lighting systems have been an absolute boon to Rock Lefatshe’s productivity, adding considerable benefit to their operations. It’s opened up another dimension – the night.”

Rock Lefatshe’s chief executive officer, Tamoledi Selane, commented, “Thanks to these lighting systems we have evolved into a successful, productive crushing business that meets its project deadlines.

We are encouraged by the excellent aftersales and field-support service we receive

from Pilot Crushtec. Of equal importance is the reliability of our equipment. Now we want to take the company to another level. We are seriously considering the purchase of a new semi-mobile modular plant to process manganese ore.”

Govender says that Rock Lefatshe’s experience with TowerLights is just one example of how a peripheral product such as a lighting system can positively influence and increase the productivity of expensive capital equipment, thereby making it more cost-effective. It enables them to sweat their assets and maximise productivity. Very importantly, this enhances your reputation, which is exactly what you need to underpin business sustainability.

He believes that there are many mines in areas like the Northern Cape with open pits that can substantially increase output using mobile lighting systems.

“These lights are exceptionally powerful.

Each tower is mounted by four 1 000 W metal halide floodlights that can be operated at a height of up to nine metres. Each light can light up an area of up to 6 400 m2. To put it another way, to turn night into day on an area the size of a soccer pitch only requires the operation of four of our units.

TowerLights also serves as insurance against Eskom’s power maintenance or

load-shedding outages and are used extensively by miners operating in areas far removed from a mains power supply.

A mining house in Namibia recently purchased a set of lights to illuminate an exploration site in a desolate, uninhabited area. In addition, the system’s inboard diesel generator is often put to work during daylight hours to provide site offices with the power to run air-conditioning, computers and refrigerators.

Turning night into day

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TECHNOLOGY

150 tonne dump truck Komatsu South Africa is launching its heaviest mechanical-drive dump truck yet to meet the growing requirements for flexible rugged fleets in the challenging mine contracting business, as well as burgeoning requirements in the mining industry.

W

ITH A 144 TONNE payload, the new Komatsu HD1500 fills a niche in the market between the manufacturer’s own 100 tonne Komatsu HD785 mechanical dump truck, and the region’s most popular 181 tonne Komatsu 730EAC electric-drive trucks.

Boasting an advanced engine and drive system, the Komatsu HD1500 has similar productivity characteristics to its electric-drive cousins, with the same go-anywhere ruggedness of other legendary mechanical-drive equipment used throughout the company’s extensive heavy-equipment range.

Ready for Africa “In many ways, the Komatsu HD1500 is aimed at contractors and mines that need the flexibility of a mechanical-drive vehicle with a larger payload. It allows them to move the trucks to different high-production mines around the continent wherever required, without the need for electric-drive service infrastructure associated with our bigger truck models,” says Louis Kidson, Komatsu South Africa key The new Komatsu HD1500

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accounts manager. With commonly available service requirements, the trucks will provide heavier, more productive options for the plethora of new mines being established throughout Africa, many of which are in remote locations. Closer to home, the mechanical-drive trucks are preferred by mining contractors as well as mines that are already equipped to service smaller mechanical trucks, but are looking to increase volumes exponentially with larger trucks.

“Our 100 tonne Komatsu HD785 has been around for many years and is a firm industry favourite. In recent years, a number of our coal mining clients have begun to push up volumes and, as a result, have enquired about bigger dump trucks. After thorough investigation, we decided to bring in the Komatsu HD1500 as the most versatile and advanced option for this type of customer and have already stocked and tooled up to enable our service technicians to be able to maintain them wherever they are in the region.

Fleet upgrades “Simultaneously, our mining contractor clients can use the machines to bid for large-scale production activities where long-term contracts are not in place. There has been a requirement for reliable 150 tonne mechanical trucks to use on a host of new projects and now we will be in a position to supply them.

“The Komatsu HD1500 dump trucks have been in operation in other areas of the world for a number of years. Many have also been used in particularly harsh remote areas and have established enviable track records. Although they

are rugged, they are also smart and are engineered to be efficient and reliable,” highlights Louis.

“Other smart feature like Komtrax Plus allows full monitoring of the machine on-site and provides technical personnel with statistical data on the operation of the machine, service requirements and information about the productivity of the machine. The trucks also benefit from the same type of proven frame as their predecessors.”

Noteworthy features and specifications include: • high-performance 1 119 kW (1 500 HP) engine • electric 7-speed transmission with skipshift, traction control and automatic speed control • Komatsu Engineered Standards’ super-strong frame design • Komtrax Plus management system • immediate diagnosis of engine, chassis and drive system components • traction control • MacPherson independent front-suspension system • 12.2 m turning radius • payload meter • retarder for constant downhill speed.

High expectations According to Louis, there is a lot of interest in the new dump trucks and Komatsu is expecting the Komatsu HD1500 to become one of its mainstay models within the Southern African mining market. Adding credence to these expectations is the fact that the first two launch units have already been sold and recently entered service on a coal mine near Johannesburg.

“The Komatsu HD1500 is a workhorse that is perfectly suited and adapted to perform in our conditions. It is easy to work on and can carry massive loads all day, every day and that is precisely what most mines are looking for,” concludes Louis.

TECHNOLOGY

Abrasion resistance Hardness does not necessarily mean a higher degree of abrasion resistance. This should be remembered otherwise it could end with catastrophic results.

By Robert F Miller

H

ARDNESS IS quite often used in the field of wear resistance as the criteria for judging alloys, castings, hardfacings and overlays. The premise is that the harder the material, the greater the wear resistance.

While this is technically correct, applying this principal across the board can lead to some catastrophic results. For example, a tool steel and chromium carbide iron with the same 600 Brinell (BHN) hardness will differ in an abrasion application by as much as five times. Why is this?

Let’s take a look at the hardness test to find some answers. An indentor, made of hardened steel or diamond, is penetrated into the material under a given load and acceleration. After withdrawal of the indentor, the diameter or the depth of the impression is measured and reported as a relative number such as Brinnel or Rockwell B, or Rockwell C, etc. The size of this impression is quite a bit larger than any of the individual grains or hard particles. This hardness test is essentially measuring the average hardness of many particles. It’s possible to think of this test as a macro hardness test.

A micro hardness test, on the other hand, measures the individual hardness of each grain or particle. How does this apply to the tool steel and chromium carbide iron? Well,

the tool steel is made up of approximately equal grains with all the same micro hardness and consequently returns the same level of macro hardness (600 BHN).

Chromium carbide iron, however, consists of very hard particles (1 200 BHN) of chromium carbide embedded in a very soft matrix (200 BHN). The individual micro hardness values of the hard carbide and the soft matrix combine to yield a macro hardness of 600 BHN. Thus, it has been demonstrated that, two materials can have the same hardness value and be completely different in structure.

Now let’s look at abrasion resistance. Let’s assume that the material that is doing the abrading has a Brinell hardness value of 750 BHN. Since it is harder than the tool steel (600 BHN), it will wear the tool steel down in short order. Conversely, since the chromium carbides in chrome carbide iron are very much harder (1 200 BHN) than the abrading particles, the wear resistance of chromium carbide iron is much greater.

From the foregoing, it becomes apparent that choosing materials to resist wear based on hardness alone and, in particular, macro hardness values, can be very risky. It is essential to understand the materials’ microstructure to establish abrasive wear characteristics. Predicting abrasive wear within

a family of materials with like microstructures is much safer. In this latter case, an increase in hardness almost certainly leads to increased wear resistance.

TABLE 1 Rockwell and Brinell cross index

ROCKWELL (RC)

BRINELL (BHN)

20 25 30 35 40 45 50 55 60 65

226 253 286 327 371 421 475 546 613 739

TABLE 2 Hardness values for common materials

MATERIAL

BHN

Mild steel 304 stainless steel Hardened tool steel Hard chromium plate Chromium carbide Tungsten carbide Titanium carbide Diamond Sand * Vickers hardness

120 250 650/700 1 000 1 200* 1 400* 2 400* 8 000* 1 000*

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TECHNOLOGY

Realising possibilities...

Intelligent 3D model

I

...from mine to market.

Resource Evaluation

Mineral Processing

Mine Planning

Tailings & Waste Management

Mining & Mine Development

Smelting & Refining

Materials Handling

Environment & Approvals

Transport to Market

Non-Process Infrastructure

WorleyParsons adds value through our full scope of services from pit to port including studies, mine planning, impact assessments, permitting and approvals, project management, construction management and global procurement.

43

countries

166

offices

37,500

N PRODUCING a detailed engineering design for the permanent surface and underground infrastructure at De Beers’ R20 billion Venetia underground diamond mine project, WorleyParsons harnessed a methodology to create an intelligent 3D model of the vertical shaft that incorporates the historic and technical information of every component. It is believed that this is the first time this methodology is being used on a vertical shaft project from the design stage and this capability is expected to become a significant market differentiator for the global WorleyParsons’ organisation, one of the world’s largest engineering, procurement, and construction management businesses.

“In using 3D modelling to design the vertical shaft from scratch, the client has been able to review our designs and have any changes incorporated and represented in the model well before fabrication even commences. This has effectively shortened and removed risk from the design process,” says Ryan Illingworth, WorleyParsons’ project manager on the Venetia project.

“Design traditionally begins with 2D modelling and the 3D environment is only then modelled when fabrication of the components begins. However, since the many separate 2D drawings are not linked to each other, there’s always a risk when it’s assembled/constructed that, there will be incompatibilities. On the Venetia project, as the design process has advanced, we’ve progressively created a 3D model that presents our customer with a visual representation of the infrastructure.

“Once the mine moves into production, management will be equipped with an intelligent 3D model of the shaft that can be used for maintenance planning and control. Because the model has a database at its core, it will also be able to integrate with other De Beers database systems.”

The draughting team at WorleyParsons deployed spent the greater part of a year prior to commencement of the design phase developing a method to network several Autodesk software packages in a complex array to allow for the creation of the intelligent 3D model.

An intelligent 3D model of the vertical shaft at De Beers’ R20 billion Venetia underground diamond mine project

people

www.worleyparsons.com

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MINING SERVICES

Remote mining camp management The people who move in where there is simply nothing but virgin bush, and erect, run and manage a remote mining camp are a breed apart. These groundbreakers provide an invaluable service.

O

NCE THE euphoria of a major diamond find has worn off, the practical realities of turning the discovery into a viable and functioning commercial mining operation begin. Recently, an Australian research team identified kimberlite deposits around the south-western slopes of Mount Meredith, in the massive Prince Charles Mountains in East Antarctica.

It is likely that the kimberlites are a result of Antarctica being once part of a supercontinent that eventually broke up into some of the most diamond-rich areas of the world. Gregory Yaxley, a geologist at the Australian National University in Canberra, said that, while kimberlite usually holds valuable diamonds within them, much less than one carat of diamond per tonne of kimberlite could be expected from these Antarctic deposits. Besides the obvious difficulties miners would face in Antarctica, mining on the continent is largely illegal. Even so, we will use this for illustrative purposes.

So, what would be involved in setting up a remote mining camp in this isolated part of the world where temperatures drop to a level most of us cannot even imagine? Antarctica is a remote, hostile environment surrounded by ice, snow and spectacular beauty. You can expect long periods of either 24 hours daylight or darkness, and

it is the coldest and windiest of the continents – although not always as cold as you might expect. It is also one of the driest continents, despite being covered in ice sheets up to 4 km thick: there is low snowfall and most of the continent is technically a desert. You survive the cold temperatures by being well trained in advance of the activities, careful how you dress, by working in a team where each watches the other for signs of hypothermia, and by having all the required equipment at hand. Taking risks is not what you are trained to do.

Given this, detailed project planning and execution will be crucial to the success of setting up this remote mining camp. Of course, your supply chain logistics will have to be exceptional and must include: • specialised accommodation, centrally heated • catering and food services • laundry • cleaning services • waste management • health services • emergency services • warehousing and asset management • vehicle fleet management • helicopter services • transportation • fuel supply and distribution.

All of this, among a plethora of other detail, is required to sustain life, and productivity.

Aerial view of the east coast of Antarctica where diamond-bearing kimberlite has been discovered

The mining equipment and mining operations are an entirely different kettle of fish. It would be like mining in the frozen wastes of Canada or Russia. Nonetheless, attention to teamwork and social interaction will be important. Living and working in this type of environment does not suit everyone, even if they think they can cut it.

Profiling people, especially the lead team, will be necessary, and a strong leader will need to be appointed.

MINING CAMP SERVICE PROVIDERS Servest provides outsourcing solutions within the mining sector: everything from security, camp management (at the inception of a mine) to sanitation and catering. ACMS Shelela provides village management services for mining, whether it’s a mobile exploration camp, a temporary construction camp or a 15-year steadystate mine village, your crew deserves more than a cold shower and a budget bed. Fedics Site Services is one of the leading sub-Saharan African suppliers of turnkey operational support for remote construction camp management and site catering.

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MINING SERVICES

A new centre of excellence

A

T THE OPENING of their new South African head office at Melrose Arch in Johannesburg, WorleyParsons CEO Digby Glover said, “Three years ago, we set out with a vision to establish a sub-Saharan African project delivery organisation and, by 2013, we had established ourselves in projects in Mozambique, Tanzania and South Africa. Being intent on partnering with our customers, and our customer’s customers, to transform the continent, we are delivering projects across all sectors.

“Our infrastructure capability has two arms, namely our public infrastructure and our resource infrastructure arms. Together, these deal with early works such as social and environmental needs, roads, rail, water treatment works, camp establishment, etc., which are necessary to develop new resource projects.

“The resource infrastructure arm is a significant part of our future business, because this is what makes a project viable. By combining the technical excellence housed in Johannesburg with our knowledge of the finer elements of African execution, we believe we will differentiate ourselves in the market.

“We offer a team of professionals experienced in delivering projects on the ground.

Our front-end advisory team interfaces with our consulting team, drawing experienced technical resources from the local and global organisation to enable the development of practical and cost-effective concepts, which can be taken through to successful project delivery.” Based on its knowledge of executing projects in Africa,

TOP WorleyParsons CEO Digby Glover ABOVE WorleyParsons’ new head office in Melrose Arch

WorleyParsons has its sights set on leveraging this capability to ensure a greater market share within the African resource energy industry.

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