The fate of gold in cupric chloride hydrometallurgy

Abstract

Because of the importance of gold in copper processing, controlled experiments were performed with gold metal and aqueous copper chloride solutions to characterize the behavior of gold under leach conditions and understand its disposition during the processing of ore concentrate and gold-containing alloys. These experiments were done under an inert atmosphere and also with exposure to air. A model of the aqueous solution resulting from leaching was also developed for correlating experimental results and predicting gold behavior. It was based on simple leach reactions for both gold and copper and the complex ions which are formed in the presence of strong saline solutions. The experimental results are compared with predictions and it is shown that the model is viable for predicting the effect of varying sodium chloride, cupric chloride and cuprous ion concentrations in leaching solutions. The effects of raising temperature and exposure to oxygen were also studied and both are shown to increase gold solubility in leach solutions. An increase in cuprous ion concentration in leach solution is shown to limit gold solubility as well as cause precipitation.