The adsorption of gold(I) on minerals and activated carbon (preg-robbing) in non-ammoniacal thiosulfate solutions - effect of calcium thiosulfate, silver(I), copper(I) and polythionate ions

Sitando, O., Senanayake, G., Dai, X. and Breuer, P. (2018) The adsorption of gold(I) on minerals and activated carbon (preg-robbing) in non-ammoniacal thiosulfate solutions - effect of calcium thiosulfate, silver(I), copper(I) and polythionate ions. Hydrometallurgy, 184 . pp. 206-217.

Abstract

The ability of some typical gangue minerals and activated carbon to adsorb gold(I) (preg-robbing) in non-ammoniacal thiosulfate solutions was examined at different calcium thiosulfate concentrations. In the absence of calcium thiosulfate, sulfide minerals such as pyrite and chalcopyrite, and carbon were highly preg-robbing with 100% gold being adsorbed within half an hour. The oxide minerals examined including kaolinite, goethite and hematite were significantly less preg-robbing under the same conditions. The presence of free thiosulfate can significantly reduce or eliminate the preg-robbing of gold on mineral surfaces. With an initial thiosulfate concentration of 0.1 M, gold adsorption by oxide minerals was completely eliminated, while that of sulfide minerals and carbon was insignificant at 0.2 M free thiosulfate.

Copper(I) was found to enhance the preg-robbing of gold by oxide minerals but to reduce the preg-robbing of gold by sulfide minerals and by carbon. Similar effect of silver(I) was observed except for chalcopyrite. Trithionate, a by-product of thiosulfate degradation, has no significant effect on the preg-robbing of gold(I). Tetrathionate, another by-product of thiosulfate degradation, significantly increases the preg-robbing of gold(I) onto pyrite. Activated carbon enhances the degradation of tetrathionate to trithionate and thiosulfate, the latter helps stabilise the gold(I) in solution.

Item Type:	Journal Article
Murdoch Affiliation(s):	School of Engineering and Information Technology
Publisher:	Elsevier BV
Copyright:	© 2018 Elsevier B.V.
URI:	http://researchrepository.murdoch.edu.au/id/eprint/42431

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