Thiosulphate leaching of gold in the Cu-NH₃₋S₂O₃²⁻-H₂O system: an updated thermodynamic analysis using predominance area and species distribution diagrams

Liu, Xiaoliang, Jiang, Tao, Xu, Bin, Zhang, Yan, Li, Qian, Yang, Yongbin, and He, Yinghe (2020) Thiosulphate leaching of gold in the Cu-NH₃₋S₂O₃²⁻-H₂O system: an updated thermodynamic analysis using predominance area and species distribution diagrams. Minerals Engineering, 151. 106336.

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Abstract

Thiosulphate, as an environmentally friendly lixiviant, is currently identified as the most promising alternative to cyanide for the extraction of gold from ores in sensitive locations. The Cu(II) ammine complexes acts as the catalytic oxidant to increase the thiosulphate leaching rate of gold, which also causes an undesirable high consumption of thiosulphate. Due to the complex solution chemistry of Cu-NH₃₋S₂O₃²⁻-H₂O system, fundamentally supported mechanisms to justify the catalytic effects and the consumption of thiosulphate are yet to be developed. Thermodynamic analysis offers essential information on which chemical species that could form and how these species influence the solution chemistry under various conditions. In this paper, predominance area and species distribution diagrams for gold leaching in the Cu-NH₃₋S₂O₃²⁻-H₂O system were constructed from a series of calculations using updated thermodynamic data. The diagrams reveal insights into the thermodynamics of gold dissolution, thiosulphate stability and redox behaviour of Cu(II)/Cu(I) couples. Analysis of the results presented in this paper can provide a theoretical basis for the complex thiosulphate leach solution chemistry that allows for a better understanding on the relationships between the redox behaviour of Cu(II)/Cu(I) couples and the behaviours of gold leaching and thiosulphate decomposition.

Item ID: 62904
Item Type: Article (Research - C1)
ISSN: 1872-9444
Keywords: Thiosulphate, Gold leaching, Thermodynamic analysis, Copper redox couples
Copyright Information: © 2020 Elsevier Ltd. All rights reserved.
Funders: National Natural Science Foundation of China (NNSFC), Qinghai Provincial Major Scientific and Technological Special Project of China (QPMSTSPC), Hunan Provincial Natural Science Foundation of China (HPNSFC), China Scholarship Council (CSC)
Projects and Grants: NNSFC Grant No. 51504293, QPMSTSPC No. 2018-GX-A7, HPNSFC Grant No. 2018JJ4038, CSC Grant 201606370128, CSC Grant 201706370222
Date Deposited: 22 Apr 2020 07:30
FoR Codes: 40 ENGINEERING > 4019 Resources engineering and extractive metallurgy > 401903 Hydrometallurgy @ 100%
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