Dissolution theory of gold in alkaline thiourea solution(Ⅲ)
———Thermodynamics on dissolution of gold in alkaline thiourea solution containing Na2SO3
———Thermodynamics on dissolution of gold in alkaline thiourea solution containing Na2SO3
(1. Department ofNonferrous Metallurgy,Central South University of Technology, Changsha 410083, P.R.China;
2. Center for Integrated Research of Science and Engineering,Nagoya University,Nagoya 464, Japan)
2. Center for Integrated Research of Science and Engineering,Nagoya University,Nagoya 464, Japan)
Abstract: The oxidants of gold were investigated in an alkaline thiourea solution containing Na2CO3, in which Na2S2O8 is a proper oxidant for dissolving gold because of in such homogeneous sulfur system coexisting complex agent, oxidant and stabilizing agent. The thermodynamic analyses were conducted on the dissolving of gold in the alkaline thiourea solution containing Na2SO3 by the oxidants oxygen or Na2S2O8. The results show that the possibility of gold dissolution reduces with increasing pH value, while oxygen acts as oxidant;and when Na2S2O8 acts as the oxidant of gold in the alkaline thiourea solution of pH 12.5, decomposition potential of thiourea decreases from the standard value 0.42V to -0.32V, also the dissolution trend of gold enhances with shifting the mix potential of the solution to the positive direction.
Key words: thermodynamic; analysis; gold; dissolution; thiourea leaching