Dissolution of gold in chalcopyrite-containing cyanide solutions
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Dissolution of gold in chalcopyrite-containing cyanide solutions YANG Wei(杨玮)1, 2, ZHANG Kai(张凯)1, 2, WANG Ya-ping(王亚平)3, LONG Tao(龙涛)1, 2, WAN He(宛鹤)1, 2, LI Hui(李慧)1, 2, WANG Qian(王倩)1, 2 1. School of Resources Engineering, Xi’an University of Architecture and Technology, Xi’an 710055, China; 2. Key Laboratory of Gold and Resources in Shaanxi Province, Xi’an 710055, China; 3. School of Foreign Languages, Baoji University of Arts and Sciences, Baoji 721013, China © Central South University Press and Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract: The gold dissolution in anoxic cyanide solution in the presence of chalcopyrite was studied with a rotating disc electrode. It was found that the presence of chalcopyrite reduced and enhanced the dissolution activity of pure gold in the low and high potential regions, respectively. The dissolution of gold was diffusion-controlled at low potentials (≤177 mV) and low cyanide concentrations (≤980 mg/L); however, above the cyanide concentration of 980 mg/L, the current density of gold decreased and the dissolution of gold changed from diffusion-control to electrochemical reaction-control. At high potentials (>177 mV), gold dissolution was always controlled by diffusion. In cyanide solution containing chalcopyrite, appropriate increase of pH value and temperature could accelerate the dissolution of gold, but high pH value would promote the generation of passivation, which was harmful for the dissolution of gold in cyanide solution. Key words: chalcopyrite; cyanide; gold; dissolution Cite this article as: YANG Wei, ZHANG Kai, WANG Ya-ping, LONG Tao, WAN He, LI Hui, WANG Qian. Dissolution of gold in chalcopyrite-containing cyanide solutions [J]. Journal of Central South University, 2020, 27(5): 1495−1502. DOI: https://doi.org/10.1007/s11771-020-4385-z.
On the surface of gold, oxygen will be reduced according to the following reaction:
1 Introduction The cyanidation has been applied in industry since 1887. It was widely applied because of its simple process, high recovery rate and strong applicability. However, the slow dissolution rate of gold is still one of the main problems of cyanidation. It has been known that gold cyanidation is an electrochemical reaction [1]. Cyanidation occurs as a result of the two redox half reactions. Anodic dissolution of gold will be oxidized according to the following reaction: Au+2CN - → Au(CN) 2- +e
(1)
O2 +2H 2O+4e ® 4OH -
(2)
Hence, many researchers used electrochemical methods to study the kinetics of gold. In aerated reagent-grade cyanide solution, KUDRYK et al [2] examined the anodic dissolution of pure gold. They found that the dissolution rate of pure gold was controlled by the diffusion of cyanide ions, whereas JEFFREY et al [3] believed that in aerated ultra-pure cyanide solutions, the dissolution rate of pure gold is very low, so the reaction is chemically controlled rather than controlled by cyanide ion
Foundation item: Project(51474169) supported by the National Natural Science Foundation of China; Project(1
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