Optimization of indium electrowinning from sulfate solutions on Ni cathode

The indium recovery via electrowinning from sulfate baths has recently gained significant attention due to the absence of toxic emissions, sealed-system requirements, human health and environmental hazards. In the present research, Ni has been considered as a cathode for indium electrowinning from sulfate baths. The influence of process parameters, temperature, pH, current density, electrolyte composition and additive additions on specific energy consumption (SEC), current efficiency (CE), as well as deposit morphology has been evaluated. The findings indicate that the indium electrowinning using Ni cathode at 40 °C temperature, 2.3 pH, 70 g/L In3+ as sulfate, 5 g/L H3BO3, 30 g/L Na2SO4 and 20 g/L Al2(SO4)3 electrolyte composition maintained a high CE of about 98% and low SEC of about 1.7 kWh/kg from 25 to 80 A/m2 current density. While increasing current density up to 100 A/m2, a maximum of about 83.3% CE with 2.4 kWh/kg SEC are obtained if 40 g/L and 30 g/L of boric acid and sodium sulfate are used, respectively. In the optimized conditions, indium deposits exhibited a lamellar morphology and crystallographic tetragonal structure.