Effect of Cations on Anodic Oxidation of Gold in Thiosulfate Solution
Thiosuifate leaching has been considered as the most promising alternative to cyanidation for the recovery of gold from ores. The chemistry of the ammonia-thiosulfate-copper system is complicated due to the simultaneous presence of complexing ligands such as ammonia and thiosulfate, the Cu(Ⅱ)-CU(Ⅰ) redox couple and the stability of thiosulfate in solution. However, acceptable gold leaching rates can be achieved by maintaining suitable concentrations of thiosulfate, ammonia, copper and oxygen in the leach solution. The leaching of gold in thiosulfate solution is an electrochemical reaction involving the oxidation of gold to gold thiosulfate and the reduction of Cu(Ⅱ) to Cu(Ⅰ). Previous studies have shown that the reaction rate of gold was much higher in the presence of ammonia thiosulfate than corresponding sodium thiosulfate. This indicates that cations may affect the anodic oxidation of gold in thiosulfate solution. The present study utilises electrochemical techniques to study the anodic oxidation of gold in thiosulfate medium in the presence of the different alkali metal and alkaline earth metal ions. It has been shown that the presence of the heavier cations such as potassium, calcium, and caesium enhance the oxidation of gold in thiosulfate solution.Leaching tests also indicated the improved recovery of gold from a sulfide ore with the addition of heavier cations. XPS results demonstrated that the binding energy for gold shifted to lower values in the presence of the heavier cations, indicating the ready formation of ion-pair with gold thiosulfate at the gold surface during adsorption.
Gold Thiosulfate Cation Leaching Electrochemistry
D. W. Feng J. S. J. van Deventer
Dept of Chemical & Biomolecular Engineering, The University of 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
2585-2590
2008-09-24（万方平台首次上网日期，不代表论文的发表时间）