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Acid leaching and dissolution of major sulphide ore minerals: processes and galvanic effects in complex systems

P. K. Abraitis^1,, R. A. D. Pattrick¹, G. H. Kelsall² and D. J. Vaughan^1,*

¹ Williamson Research Centre for Molecular Environmental Science, and Earth Sciences Department, University of Manchester, Manchester M13 9PL, UK
² Department of Chemical Engineering, Imperial College London, London SW7 2AZ, UK

^* E-mail: david.vaughan{at}man.ac.uk

The kinetics and mechanisms of dissolution of the major base metal sulphide minerals, pyrite, chalcopyrite, galena and sphalerite in acidic (chloride) media have been investigated. Minerals were ground in air, then dissolved in air-equilibrated solutions at pH 2.5, while monitoring the redox potential. Solution samples were analysed by ICP-AES and HPLC, and surfaces of residual sulphides analysed using XPS. Dissolution of aerial oxidation products on pyrite particles in the first 15 min apparently led to a sulphur-rich surface, and was followed by slower dissolution of pyrite itself, driven by oxygen reduction, and resulting in net production of protons. Chalcopyrite dissolution resulted in a Cu, S-rich (near) surface layer, accompanied by net consumption of protons. Apparently incongruent dissolution of galena and sphalerite may reflect the formation of elemental S at the surface. The rates of dissolution of chalcopyrite, galena and sphalerite in the presence of pyrite were determined, respectively, as 18, 31 and 1.5 times more rapid than in single-mineral experiments. These data were consistent with galvanically-promoted mineral oxidation of the other sulphides in the presence of pyrite. In the case of galena, the experimental data suggested extensive release of Pb ions and development of a sulphur-rich surface during galvanically-promoted dissolution.

KEYWORDS: acid leaching, sulphides, pyrite, chalcopyrite, galena, sphalerite

This article has been cited by other articles:

				M. P. Asta, J. Cama, J.M. Soler, R .S. Arvidson, and A. Luttge Interferometric study of pyrite surface reactivity in acidic conditions American Mineralogist, April 1, 2008; 93(4): 508 - 519. [Abstract] [Full Text] [PDF]

				K. M. Rosso and D. J. Vaughan Reactivity of Sulfide Mineral Surfaces Reviews in Mineralogy and Geochemistry, January 1, 2006; 61(1): 557 - 607. [Full Text] [PDF]