Purification of crude indium by two-stage cyclone electrowinning

Abstract

A possible process for the purification of crude indium by two-stage cyclone electrowinning was proposed. In accordance with a linear sweep voltammetry (LSV) results and the evaluation of the diffusion coefficient (D=6.15×10−11 cm2/s), indium electrodeposition in In2(SO4)3 solution was controlled by a diffusion-controlled irreversible process, and mass transfer can be significantly enhanced by electrolyte flow. During the 1st-stage indium cyclone electrowinning, a current efficiency (CE) of 80.15%, specific energy consumption (SEC) of 2.11 kW·h/kg and average cell voltage (ACV) of 2.04 V were achieved under the optimum conditions. Meanwhile, the purity of indium increased from 94.34% to 99.95%. During the 2nd-stage indium cyclone electrowinning, 98.95% purity of cathode indium was conducted by electrowinning under the optimum conditions, while the CE, SEC, and ACV were 75.23%, 2.23 kW·h/kg and 2.40 V, respectively. After two-stage cyclone electrowinning, the comprehensive recovery of indium is as high as 98.22%.