Removal of zinc cyanide from a leach solution by an anionic ion-exchange resin

The Merrill-Crowe process has been used for the precipitation of silver metal from cyanide solutions. Although the Merrill-Crowe system operates effectively most of the time, if the recycled solution contains a high zinc cyanide concentration, it leads to a decrease in efficiency of the solution as a solvent. In this study an anionic ion-exchange resin, Lewatit MP62, was used for the treatment of excess zinc cyanide from alkaline leach solutions. Ion-exchange tests were conducted in a laboratory-scale glass column using recycled water from the 100th Year Silver Cyanidation Plant in Turkey. It contains 474 mg/l Zn and 720 mg/l CN. The exchange capacity of the resin and the initial pH effect on the loading capacity were determined by breakthrough curves. It was found that zinc cyanide was completely removed from a recycled solution until it reached the breakthrough point.