A ROTATING EQCM STUDY OF THE EFFECTS OF ELECTROLYTES, ADDITIVES AND METAL IMPURITIES ON THE ELECTRODEPOSITION OF GOLD(I) THIOSULFATE

摘要

The work presented here is a study of the electroreduction of the gold(I) thiosulfate complex to produce metallic gold. Thiosulfate has been suggested as an alternative to cyanide for use in gold ore processing. The reduction of gold thiosulfate in electrolytes of sodium, potassium and ammonium salts was investigated. It has been found that gold thiosulfate reduction proceeds most readily in the presence of ammonium cations. It will be shown that the presence of ammonia in these solutions results in a pH increase which has a detrimental effect on the reduction of gold thiosulfate. The effect of trace metal impurities on the reaction has also been studied. The presence of 2 parts per million of copper or silver ions enhances the gold deposition reaction through what is believed to be the formation of a gold/copper or gold/silver alloy.