Sustainable Mining and Metallurgy

The indium of crude indium casting slag mainly exists in the form of indium trioxide, indium oxychloride and indium hydroxide. In this paper, acid leaching-replacement-electrolysis process was used to recover and treat crude indium casting slag, and the leaching behavior of indium in hydrochloric acid leaching process was studied.The E-pH diagram analysis of Cl-In-H2O system shows that controlling the reaction pH＜2 and increasing the potential are beneficial to the decomposition of indium compounds in the casting slag.The leaching test results show that the optimum reaction conditions are as follows: liquid-solid ratio of 2.0, hydrochloric acid concentration of 7mol/L, reaction time of 4h, stirring speed of 300r/min and reaction temperature of 25℃.Under these conditions, the leaching rate of indium was 52.25%, and the concentration of indium in the leaching solution could reach 165g/L. The sponge indium with purity of 99.95% was obtained by replacement with aluminum plate, which met the quality requirements of electrolytic anode plate.