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Journal article
The combined leaching of copper, gold and uranium in chloride solutions. II. Concentrate leach tests
Hydrometallurgy, Vol.231, 106407
2025
Appears in Open Access via Read & Publish Agreements
Abstract
This study of the simultaneous leaching of copper, gold and uranium from a flotation concentrate is aimed at establishing the conditions that could be applied in a possible heap leach process that would recover all three metals (plus silver, if present) in a single step. The results obtained in this study confirm the results obtained in Part I (Nicol et al., 2024) 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 in 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.
•Enhanced rates for leaching of chalcopyrite in acidic chloride solutions with chlorate.•Chlorine generated by the chlorate-chloride reaction is the active oxidant.•The dissolution of gold requires higher potentials of at least 1.0 V.•At low chloride concentrations (1 M), gold is not dissolved because of apparent passivation.•Passivation is probably the result of the formation of a layer of Au2S on the gold surface
Details
- Title
- The combined leaching of copper, gold and uranium in chloride solutions. II. Concentrate leach tests
- Authors/Creators
- M. Nicol - School of Information Technology and Engineering, Murdoch University, Perth, WA 6150, AustraliaK. Ye - BHP Billiton Innovation Pty Ltd, 171 Collins Street, Melbourne, Vic 3000, AustraliaN. Garrard - BHP Billiton Innovation Pty Ltd, 171 Collins Street, Melbourne, Vic 3000, Australia
- Publication Details
- Hydrometallurgy, Vol.231, 106407
- Publisher
- Elsevier B.V
- Number of pages
- 9
- Grant note
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
- Identifiers
- 991005707262107891
- Copyright
- © 2024 The Authors.
- Murdoch Affiliation
- School of Information Technology
- Language
- English
- Resource Type
- Journal article
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- Citation topics
- 7 Engineering & Materials Science
- 7.229 Mineral & Metal Processing
- 7.229.774 Bioleaching
- Web Of Science research areas
- Metallurgy & Metallurgical Engineering
- ESI research areas
- Materials Science