TRANSACTION PAPER

Flowsheet considerations for copper cobalt projects

A. Nisbett^I; K. Baxter^II; K. Marte^III; M. Urbani^IV

^ICognis Corporation,USA
^IIBateman Engineering Pty Ltd, Australia
^IIIBateman Engineering Canada Corporation, Canada
^IVWestern Minerals Technology, Australia

SYNOPSIS

The Copperbelt areas of Zambia and the Democratic Republic of Congo (DRC) have recently been seeing the development of a significant number of new projects. Due to the current economic climate, some of these projects have been delayed but the region remains an important resource for copper and cobalt for future years.
Many of these projects will utilize an agitation leach followed by solvent extraction and electrowinning to recover both copper and cobalt. The flowsheet route for copper is fairly well established while the processing options for cobalt vary considerably depending on the final product (metal or salt) the operator wishes to make. The mineralogy of ores in the area is typically associated with high gangue acid consumption during the leaching process. This has resulted in acid availability to the area being constrained and acid prices have risen accordingly.
Agitation leach circuits, typically, have a tight water balance which needs to be maintained and a bleed of process liquor needs to be continuously removed from the circuit in order to maintain this balance. This bleed, typically, contains fairly high levels of acid and requires neutralization prior to tailings disposal or secondary metal recovery. It is, therefore, desirable to minimize the acid concentration in this bleed stream in order to decrease total acid requirements and neutralization costs for the process plant.
An in depth case study by Cognis and Bateman Engineering evaluated three different flowsheets with the aim of determining relative operating costs between the three alternatives, together with differences in plant capital cost requirements.

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References

1. HOLMES, J.A., DEUCHAR, A.D., STEWART, L.N., and PARKER, J.D. Design, Construction and Commissioning of the Nchanga Tailings Leach Plant. Extractive Metallurgy of Copper. J Yannopoulos and J Agarwal (eds.), Metallurgical Society of AIME 1976, vol. II, pp. 907-925.         [ Links ]

2. KORDOSKY, G., FEATHER, A., and CHISAKUTA, G. The Copperbelt of Africa - New Plants and New Technology in Copper Hydrometallurgy. Proceedings Alta 2008 Copper Conference, Perth, Australia 2008.         [ Links ]

3. NISBETT, A., FEATHER, A., and MILLER, G. Implementation of the Split Circuit™ Concept into Copper Agitation Leach Plants. Proceedings HydroCopper 2007, Vina del Mar, Chile, 2007, pp. 185-190.         [ Links ]