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HEAP LEACH 42 E&MJ; • MAY 2017 www.e-mj.com At BHP Billiton's massive Olympic Dam copper mine in South Australia, that company is also viewing adjust- ments to its heap leach operations in a widely inclusive format — in this case, a plan more attuned to maximizing its current physical assets to significantly increase Olympic Dam's production rate from its current output of more than 200,000 mt/y. In July 2016, Jacqui Mc- Gill, asset president–Olympic Dam, told an audience at a South Australia Cham- ber of Mines event that: "...with some efficient investment of capital and fur- ther optimization, Olympic Dam could further increase capacity, potentially up to 280,000 mt of copper per year." McGill went on to say, "We also retain attractive options beyond 280,000 mt/y. Continuing expansion underground, and successful on-site application of heap leach technology could provide an oppor- tunity for further growth. This would see heap leach working in parallel with our current concentrator and uranium leach plant, feeding into an expanded smelting and refining facility. This could allow us to produce up to 450,000 mt/y of copper, while continuing to use the current stope mining method with a significantly small- er footprint and capital cost than the prior open-cut design. "Opening up the Southern Mine area will provide us with a much better grade in copper and copper sulphur ratio in or- der to maximize the metal units through the existing surface facility," she con- tinued. "For some time now, you would have heard us talk about the application of heap leach technology at Olympic Dam as a potential low cost processing option for the future. Many of you might also recall that we commenced column testing at Wingfield in 2010, which was followed by the 2013 commencement of the larger CRIB based testing. "This test-work is moving into another exciting phase, with smelter pilot plant test work soon to commence at Outotec in Finland. This test work…is aiming to determine the effectiveness of smelting concentrate from the heap leach pro- cess with existing OD concentrate in a pilot flash matte smelter. It then aims to produce blister copper in a novel hybrid DBF smelter arrangement, also at pilot scale. The findings from the testing are being used to assess the smelting pro- cess and technology alternatives for the concentrate generated from heap leach. The test work will be using around 1.5 mt of Olympic Dam ripios concentrate which has been produced from the existing heap leach CRIB demonstration facilities at Wingfield, along with 2 mt of existing Olympic Dam concentrate." Back to the Not-so-Basics However, not all improvements in heap- leach technology start at the top; basic machinery used in the process continues to improve, as illustrated by the sidebar to this article and other innovations in- volving fundamental equipment, such as agglomerator drums used to add cement to crushed ore to minimize fines be- fore placement on the heap. Even these seemingly elementary units now offer sophisticated control capabilities, ac- cording to Sepro Mineral Systems Corp., which points out that its line of heavy duty, tire-driven agglomeration drums are equipped with a variable frequency drive (VFD) package, allowing the equipment's operation to be fine-tuned. Their Rotary Control Console (RCC) component fea- tures a touch-screen HMI (Human Ma- chine Interface), which is used to control and monitor the operating parameters. When equipped with the company's Au- topac option, the drums include a jacking cradle, tire pressure sensors, and hard- wired safety limit switches. The tire drive system allows individ- ual tires to be removed without compli- cated shaft, bearing and coupling ar- rangements, according to the company. The tires are mounted on purpose-built wheel assemblies, which are driven by a bevel/helical gearbox direct connected to the electric motor. Starting and speed control is done via an AC variable fre- quency drive. Sepro said it recently completed de- livery of three of these drums to mining customers in Indonesia, Mexico and Peru. The 3.6 x 10-m drums are currently the largest size manufactured by Sepro and although the units use mainly standard, off the shelf major components, custom- ized features can be added to support client specific requirements: in this case, two of the three units included a newly developed, Sepro-manufactured liner that is offered as a more affordable option to traditional alternatives. Already used in Sepro's Falcon gravity concentrators, the liner material has demonstrated longer wear resistance, reduced downtime and other opportunities for overall cost sav- ings, according to the company. In addition, the delivered units offer multiple angle settings to adjust drum slope, providing tighter control when mon- itoring speed and tonnage by enabling the drum to be adjusted to a shallower or steeper angle as needed. And, in one particular instance, a client had request- ed a redesigned discharge chute to work with their conveyor system. Sepro said its team was able to develop a unique solu- tion that met the client's requirements without compromising the performance of the machine, allowing it to work with their existing conveyor system. Sepro Mineral Systems recently delivered three large agglomeration drums, similar to those shown here, to heap leach operators in Indonesia, Mexico and Peru. The 3.6 x 10-m units are the largest models offered by Sepro, and include customized features to meet specific customer application requirements.