Behavior of S2O32− and SO32− in sulfur-bearing aqueous solution system for gold leaching

The concentrations of S2O32− and SO32− were measured in gold leaching systems, including thiosulfate system, polysulfide system and the modified lime sulfur synthetic solution (ML) system in the process of chemical reaction. The interactions among S2O32−, SO32− and S2− were discussed. The behavior mechanism of sulfur-bearing reagents was proposed to describe the process reactions and their Gibbs free energy. The proper quantity oxygen and SO32− reduce decomposition of S2O32− and react with sulfur derived from the decomposition of SX2−. So, SO32− ions have action to stabilize sulfur-bearing system and are favorable to leach gold.