Analysis of ionic equilibria and electrowinning of indium from chloride solutions

The effects of variables on the current efficiency and cell voltage of indium electrowinning from chloride solution have been examined. Ionic equilibria for the InCl3-HCl-NaOH-H2O system at 25degreesC was analyzed and the experimentally measured pH values agreed well with those calculated from the analysis. The initial pH of electrolyte solution, reaction temperature and current density had negligible effect on the current efficiency and cell voltage increased linearly with increasing current density. In order to achieve current efficiency of 90% at the current density of 100 mA/cm(2), the initial concentration of indium and NaCl should be higher than 50 g/L.