Copper interaction during the dissolution of gold

A certain amount of gold is unknowingly lost in the presence of native copper, most probably due to a cementation mechanism, during extraction from its ores. In this study, the cementation of gold onto copper was evaluated using suspended particles of synthetic and native copper. It was shown that metallic copper causes the cementation of gold from gold cyanide solution, the rate of which is strongly dependent on temperature and the initial concentration of cyanide and copper. In the presence of excessive cyanide and dissolved oxygen, the cemented gold redissolves. Thermodynamic study, based on the CHEMIX program, showed that the distribution of copper and gold cyanide species in the copper-gold-cyanide-water system is strongly dependent on the solution pH and initial CN−/Cu molar ratio (copper and cyanide concentrations) and confirmed the experimental trends observed.