The combined leaching of copper, gold and uranium in chloride solutions. II. Concentrate leach tests
Year: 2024
Type: article
Abstract: The results obtained in this study confirm the results for the dissolution of chalcopyrite electrodes obtained in Part I (Nicol et al, 2023) that enhanced rates for leaching of chalcopyrite from flotation concentrates from two different sources can be obtained in acidic chloride solutions in the presence of chlorate ions. The measurements of the solution potentials during leaching with chlorate are similar to those obtained previously and confirm that chlorine generated by the chlorate-chloride reaction is the active oxidant.Uranium is dissolved even the absence of chlorate by iron (III) as the oxidant. The latter is re-generated by reaction of iron (II) with chlorate. The dissolution of gold requires higher potentials, and it is only leached when the potential approaches 1.0 V in concentrated chloride solutions. At low chloride concentrations (1 M), gold is not dissolved because of apparent passivation.An electrochemical study of the behaviour of gold in chloride solutions in the presence of sulfide ions has shown that the passivation is probably the result of the formation of a layer of Au2S on the gold surface at low potentials before the addition of chlorate to the leach solutions i.e., before the generation of sufficient chlorine concentrations. At potentials above about 0.95 V Au2S is unstable being oxidised to AuCl2- and elemental sulfur thereby eliminating passivation.
Source: Hydrometallurgy
Authors: M. Nicol, K. Ye, N. Garrard
Institutions: Murdoch University, BHP (Australia)
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,220
Funder: BHP
OpenAlex ID: W4403118506