Mechanisms of sulfide ion oxidation during cyanidation. Part II : Surface catalysis by pyrite

Hewitt, D.M., Breuer, P.L., Jeffrey, M.I., & Naim, F. (2009) Mechanisms of sulfide ion oxidation during cyanidation. Part II : Surface catalysis by pyrite. Minerals Engineering, 22(13), pp. 1166-1172.

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Abstract

The mechanisms and the reaction products for the oxidation of sulfide ions in the presence of pyrite have been established. When the leach solution contains free sulfide ions, oxidation occurs via electron transfer from the sulfide ion to dissolved oxygen on the pyrite mineral surface, with polysulfides being formed as an intermediate oxidation product. In the absence of cyanide, the polysulfides are further oxidised to thiosulfate, whilst with cyanide present, thiocyanate and sulfite are also formed from the reaction of polysulfides with cyanide and dissolved oxygen. Polysulfide chain length has been shown to affect the final reaction products of polysulfide oxidation by dissolved oxygen. The rate of pyrite catalysed sulfide ion oxidation was found to be slower in cyanide solutions compared to cyanide free solutions. Mixed potential measurements indicated that the reduction of oxygen at the pyrite surface is hindered in the presence of cyanide. The presence of sulfide ions was also found to activate the pyrite surface, increasing its rate of oxidation by oxygen. This effect was particularly evident in the presence of cyanide; in the presence of sulfide the increase in total sulfur from pyrite oxidation was 2.3 mM in 7 h, compared to an increase of <1 mM in the absence of sulfide over 24 h.

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ID Code: 73801
Item Type: Journal Article
Refereed: Yes
DOI: 10.1016/j.mineng.2009.06.002
ISSN: 0892-6875
Divisions: Current > Research Centres > Centre for Tropical Crops and Biocommodities
Current > QUT Faculties and Divisions > Science & Engineering Faculty
Copyright Owner: Copyright 2009 Elsevier
Copyright Statement: This is the author’s version of a work that was accepted for publication in Minerals Engineering. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Minerals Engineering, [VOL 22, ISSUE 13, (2009)] DOI: 10.1016/j.mineng.2009.06.002
Deposited On: 11 Jul 2014 00:40
Last Modified: 14 Mar 2016 22:18

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