Study on Mechanism of Gold Leaching by Thiourea in the Presence of Sodium Sulphite

来源期刊：中南大学学报(英文版)2000年第3期

论文作者：HU Yun-hua GUO Guang-fa QIU Guan-zhou

文章页码：113 - 116

Key words：gold leaching; thiourea; sodium sulphite; mechanism

Abstract: The linear potential sweep voltammetry and electrochemical methodswere used to study the mechanism and kinetics of gold dissolution in thiourea solution in the absence and presence of sodium sulphite.The results showthat in the absence of sodium sulfite the dissolution rate of gold in thiourea solution is relatively slow and it increases with the increase of the concentration of thiourea and decreases with pH. Thiourea is easily oxidized to formamidine disulphide, which reduces the leaching efficiency and increases reagent consumption. In the presence of sodium sulphite, the effective concentration of thiourea is increased and the dissolution rate of gold in thiourea solution is greatly increased. The activation energy required for gold dissolution in thiourea solution with sodium sulphite is 20.9 kJ·mol^-1 which is much lower than 55.0 kJ·mol^-1 in the absence of sodium sulphite. It is evident that sodium sulphite has a significant effect on the electrochemical reaction kinetics of gold in thiourea solution.