On-line version ISSN 2411-9717
Print version ISSN 0038-223X
J. S. Afr. Inst. Min. Metall. vol.109 n.5 Johannesburg May. 2009
Integrated piloting of a thermophilic bioleaching process for the treatment of a low-grade nickel-copper sulphide concentrate
J.W. Neale; S.W. Robertson; H.H. Muller; M. Gericke
Mintek Biotechnology Division, South Africa
Mintek was a leading participant in the BioMinE project between 2004 and 2008. This project, which was funded in part by the European Commission, was aimed at the development of biotechnology for the minerals industry in Europe. Mintek's research programme focused mainly on the development of integrated bioleach-based processes for the recovery of base metals from complex, low-grade sulphide concentrates. Specific European mineral resources were targeted and used in integrated piloting campaigns involving bioleaching, solution purification, and metals recovery.
This paper describes the use of thermophilic bioleaching for the recovery of nickel and copper from a low-grade nickel-copper concentrate produced at the Aguablanca Mine in southern Spain. Currently, the Aguablanca Mine produces a bulk nickel-copper concentrate for sale to a smelter, and the proposition is to increase the profitability of the operation by the on-site production of metal or metal intermediate.
Initially, bench-scale bioleach tests were conducted to determine the bioleach operating conditions. These tests included an evaluation of mesophilic, moderately thermophilic and thermophilic microorganisms. In order to achieve sufficiently high levels of both copper and nickel extraction, a thermophilic process was selected-this was necessary for leaching of the refractory chalcopyrite that occurs in this concentrate. Additional bench-scale test work was carried out to derive a conceptual process flowsheet for the solution purification and metals recovery circuit.
The results of the bench-scale tests were used to design, construct and commission an integrated pilot plant, which was subsequently operated at Mintek for over seven months. During this time, the solution purification and metals recovery processes were optimized, and all recycle loops were closed. The final process flowsheet included the following unit operations: concentrate regrinding, thermophilic bioleaching at 70°C, primary iron removal using limestone, copper solvent extraction and electrowinning, secondary iron removal, nickel hydroxide precipitation using magnesia, and final solution purification using lime. Where applicable, process solutions were recycled to preserve water.
The process design data derived from this pilot-plant campaign formed the basis for a conceptual engineering study for the developed process. In the study, mass and energy balances were derived, and a process flowsheet was developed and used as the basis for estimating the capital and operating costs of the process. This enabled a preliminary economic analysis of the process to be undertaken. The findings of this study are discussed.
“Full text available only in PDF format”
1. MORIN, D., LIPS, A., PINCHES, T., HUISMAN, J., FRIAS, C., NORBERG, A., and FORSSBERG, E. BioMinE-Integrated project for the development of biotechnology for metal-bearing materials in Europe. Hydrometallurgy, vol. 83, 2006. pp. 69-76. [ Links ]
2. MORIN, D., PINCHES, T., HUISMAN, J., FRIAS, C., NORBERG, A., and FORSSBERG, E. Progress after three years of BioMinE-Research and Technological Development project for a global assessment of biohydrometallurgical processes applied to European non-ferrous metal resources. Hydrometallurgy, vol. 94, 2008. pp. 58-68. [ Links ]
3. WATLING, H.R. The bioleaching of sulphide minerals with emphasis on copper sulphides-A review. Hydrometallurgy, vol. 84, 2006. pp. 81-108. [ Links ]
4. WATLING, H.R. The bioleaching of nickel-copper sulfides. Hydrometallurgy, vol. 91, 2008. pp. 70-88. [ Links ]
5. PAVLIDES, A.G. and FISHER, K.G. The Kasese cobalt project. Extraction Metallurgy Africa '98. Johannesburg, The South African Institute of Mining and Metallurgy, 1998. 20 pp. [ Links ]
6. VAN STADEN, P.J. The Mintek/Bactech copper bioleach process. ALTA Copper Hydrometallurgy Forum. Brisbane, 19-21 Oct., 1998. [ Links ]
7. CLARK, M.E., BATTY, J., VAN BUUREN, C.B., DEW, D.W., and EAMON, M.A. Biotechnology in minerals processing: Technological breakthroughs creating value. Hydrometallurgy, vol. 83, 2006. pp. 3-9. [ Links ]
8. PINCHES, A., MYBURGH, P.J., and VAN DER MERWE, C. Process for the rapid leaching of chalcopyrite in the absence of catalysts. US Patent 6,277,341: Appl.: 3 March 1997: Acc. 21 August 2001. [ Links ]
9. BATTY, J.D. and RORKE, G.V. Development and commercial demonstration of the BioCOP™ thermophile process. Hydrometallurgy, vol. 83, 2006. pp. 83-89. [ Links ]
10. ANONYMOUS. Lundin Mining Corporation Annual Report 2007. Lundin Mining Corporation, 2008. 78 pp. [ Links ]
11. CARTER, A.J. Economic comparison of the alternative methods for the recovery of gold from refractory ores. Colloquium: Bacterial Oxidation. Johannesburg, South African Institute of Mining and Metallurgy, June 1991. [ Links ]
12. ANONYMOUS. Aguablanca nickel-copper feasibility report. vol. 1, Metallurgical Design and Management (Pty) Limited. [ Links ]
13. ANONYMOUS. Fenix hydrometallurgical expansion preliminary assessment report. Rev. 1, Hatch Limited, 2006. 176 pp. [ Links ]
14. TAYLOR, A., FAIRLEY, H., and WINBY, R. Re-opening of the Radio Hill Nickel project, Western Australia using bacterial leaching of nickel sulphide concentrates. ALTA 1997 Nickel/Cobalt Pressure Leaching and Hydrometallurgy Forum, Perth. ALTA Metallurgical Services, Melbourne, 1997. 34 pp. [ Links ]