Thiosulfate Leaching of Gold in the Presence of Thiourea
Thiosulfate as an alternative lixiviant for gold has received much attention in recent years due to the growing environmental concerns over the use of cyanide. Cu(Ⅱ) is used to catalyze the oxidation of gold and ammonia is to stabilize Cu(Ⅱ) in alkaline solution. However, the presence of Cu(Ⅱ) enhances the oxidative degradation of thiosulfate. The high consumption of reagents has made thiosulfate leaching uneconomical to date, in comparison with cyanide leaching. Therefore, further investigations are required to leaching under low reagent concentrations over extended periods where reagent consumption is low and gold leaching rate is low as well. It is thus necessary to find addifives to enhance gold dissolution in the thiosulfate leaching system. Electrochemical studies using rotating gold disc showed that the oxidation of gold in ammoniacal thiosulfate solution increased significantly in the presence of a small amount of thiourea and the beneficial effect increased with an increase in the thiourea concentration up to 7.2 mM. Thiourea improved gold extraction in the thiosulfate leaching of gold from a sulfide ore under low reagent concentrations. Excessive addition of thiourea inhibited the leaching of the gold ore. The decomposition of thiosulfate was reduced with the presence of thiourea. X-ray Photoelectron Spectroscopy (XPS) results indicated that thiourea likely decomposed to sulfide and formed gold sulfide species at the gold surface.
Leaching Thiosulphate Gold Thiourea Electrochemistry
D. W. Feng J. S. J. van Deventer
Dept of Chemical & Biomolecular Engineering The University of Melbourne, Melbourne, Australia
国际会议
XXIV International Mineral Processing Congress(第24届国际矿物加工大会)
北京
英文
2731-2736
2008-09-24（万方平台首次上网日期，不代表论文的发表时间）