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:: Mintek and NICICO to Demonstrate Copper Heap Bioleach Process
Mintek has entered into a collaborative agreement with the National Iranian Copper Industries Company (NICICO) for the large-scale piloting of Mintek's heap bioleaching technology for chalcopyrite-bearing copper ores.The programme is aimed at proving the technology at a large scale, and generating reliable operating information for further scale-up to commercial-scale operations. In terms of the collaboration agreement, NICICO will fund the two-year project and the technology will be jointly owned. NICICO will have the exclusive right to apply the technology in Iran and in any project in any other country where it holds a beneficial interest equal to or greater than ten per cent. Mintek will have the exclusive right to exploit the technology in any other project in any other country outside Iran.
The project involves the construction and operation of two or three leach heaps, each containing about 20 kt of low-grade ore, at NICICO's Sarcheshmeh Copper Complex in southern Iran. The copper-bearing pregnant solution will be upgraded by solvent extraction and fed to the existing electrowinning (SX/EW) facility.
Preparatory work is under way at Mintek on the process design specifications, and it is expected that on-site construction will commence in the third quarter of 2004, with start-up early in 2005. Bioleaching experts from Mintek will be on-site to assist NICICO's engineers and hydrometallurgical staff during the commissioning and operating phases of the project, and NICICO personnel will also visit Mintek for specialised training.
The majority of the world's known undeveloped copper resources are low-grade chalcopyrite ores, and the successful adaptation of heap bioleaching for these deposits could have a major impact on the copper industry. However, although heap bioleaching is an established and cost-effective technology for secondary copper sulphides, its application to primary chalcopyrite ores is not straightforward. In particular, it is extremely difficult to achieve acceptable copper leaching kinetics.
Mintek has identified the requirements for the successful bioleaching of chalcopyrite in stirred-tank reactors, and together with partners Industrias Peņoles SA de CV and BacTech Enviromet Corporation, demonstrated the process on a large integrated pilot plant in Monterrey, Mexico, in 2001-2002. Mintek's proprietary technology for heap bioleaching includes an innovative monitoring and control strategy that maintains the optimum leaching conditions within the heap, and balances the operation to achieve the best trade-off between recovery and costs.
Sarcheshmeh is one of the world's largest copper mines, with a total ore reserve of about 1200 Mt at an average grade of 0.70 per cent copper. The porphyry-type orebody is mined by open-pit methods, and the sulphide ore processed by milling and flotation. The copper concentrate is smelted and electrorefined on-site. Annual production is about 145 kt of cathode copper. Sarcheshmeh is currently completing the first stage of a two-stage expansion that will lift concentrate production from about 430 kt/a to 700 kt/a. The company also plans to begin treating the abundant low-grade sulphide reserves, which cannot be processed economically by milling/flotation and smelting. This aspect of the expansion project would not be limited to the Sarcheshmeh Copper Complex, but would also be applicable to other low-grade sulphide deposits in Iran.
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