Abstract The research presented contributes to the global goal of responsible production by providing robust tools for the optimization of gold dissolution in cyanide-free gold leaching solutions, which represent emerging non-toxic gold technologies. In the current study, gold dissolution was investigated in ferric and cupric chloride solutions. The effect of the redox potential on the open circuit potential (OCP) and dissolution rate of gold was investigated experimentally in the parameter range of T = 25–95 °C, [Fe3+/Cu2+] = 0.02–1.0 M, [Cl−] = 1–5 M, pH = 0.0–2.0, and ωcyc = 2500 RPM. A high rotational speed was chosen to minimize the effects of limited mass transfer rate. The aim was to provide tools for estimating the gold dissolution rate in ferric and cupric chloride solutions, using the solution properties. The results showed that redox potentials, OCPs, and dissolution rates were constantly higher in ferric chloride solutions compared to corresponding cupric chloride solutions. The multilinear regression models for redox potential showed that a rise in temperature and oxidant concentration increased the redox potential in both ferric and cupric chloride solutions. However, an increase in the chloride concentration decreased the redox potential in ferric chloride solutions, whereas the effect was the opposite in cupric solutions. A rise in the pH value increased the redox potential in ferric solutions, but this was found to be an insignificant variable in cupric chloride leaching within the investigated parameter range. The redox potential had a positive correlation with OCP and the logarithm of the gold dissolution rate in both investigated systems. The results suggest that, in the chloride leaching systems examined, the solution properties can be used to determine the redox potential, and furthermore, the redox potential can be used to estimate the gold dissolution rate. This study provides an experimentally verified tool for the robust estimation of the gold dissolution rate in chloride systems.

中文翻译：

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氧化还原电位和OCP对氯化铁和氯化铜浸金的影响

摘要 本研究通过提供强大的工具来优化无氰浸金解决方案中的金溶解，为实现负责任生产的全球目标做出贡献，无氰浸金解决方案代表了新兴的无毒金技术。在当前的研究中，研究了金在氯化铁和氯化铜溶液中的溶解。在 T = 25–95 °C, [Fe3+/Cu2+] = 0.02–1.0 M, [Cl−] 的参数范围内实验研究了氧化还原电位对开路电位 (OCP) 和金溶解速率的影响= 1–5 M，pH = 0.0–2.0，ωcyc = 2500 RPM。选择高转速以最小化有限传质速率的影响。目的是提供工具，用于使用溶液特性来估计在氯化铁和氯化铜溶液中的金溶解速率。结果表明，与相应的氯化铜溶液相比，氯化铁溶液中的氧化还原电位、OCP 和溶解速率始终较高。氧化还原电位的多元线性回归模型表明，温度和氧化剂浓度的升高会增加氯化铁和氯化铜溶液中的氧化还原电位。然而，氯化物浓度的增加降低了氯化铁溶液中的氧化还原电位，而铜溶液中的效果则相反。pH 值的升高会增加三价铁溶液中的氧化还原电位，但在所研究的参数范围内，这对于氯化铜浸出来说是一个微不足道的变量。在两个研究系统中，氧化还原电位与 OCP 和金溶解速率的对数呈正相关。结果表明，在所研究的氯化物浸出系统中，溶液性质可用于确定氧化还原电位，此外，氧化还原电位可用于估计金溶解速率。本研究为可靠估计氯化物系统中的金溶解速率提供了一种经过实验验证的工具。