Electrochemical deposition of silver and gold from cyanide leaching solutions

A systematic voltammetric study developed in this work allows the determination of the potential range at which the selective deposition of gold and silver is carried out in the presence of a high content of copper. As a first approach, laboratory solutions prepared with a high content of cyanide and copper and low values of gold and silver are used; later, the methodology is applied to leaching solutions of industrial origin.The chemical speciation and microelectrolysis studies showed that copper deposition occurs at more negative potentials than deposition of gold and silver. Also, the voltammetric study of a cyanide solution containing low concentrations of Au(I) and Ag(I), free of and with high concentration of Cu(I) was carried out. The study shows the potential range at which Au(I) and Ag(I) are reduced despite the high concentration of the Cu(I) ions. The deposition of gold and silver was not interfered with by the high concentration of Cu(I) ions when the leaching solution was electrolyzed in a laboratory electrochemical reactor FM01-LC with a reticulated vitreous carbon (RVC) cathode.