Electrolysis studies by the Bureau of Mines have demonstrated that zinc and copper electrowinning can be combined with the electrochemical production of sodium perchlorate in a cationic membrane cell to achieve a significant decrease in the use of electrolysis energy. Current efficiencies exceeding 88 and 80 pct were obtained for electrowinning and electrochemical production, respectively, using typical current densities, electrolyte compositions, and electrolysis periods. The cationic membrane effectively separated the two half-cells, allowing as low as 1.5 pct (0.9 G) of the zn2+, 0.02 pct (0.01 G) of the cu2+, 0.9 pct (0.25 G) of the clo4-, and 1.0 pct (2.9 G) of the so4 2-, to interdiffuse during electrolysis.
Proc. Electrochem. in Min.& Met. Proc., Electrochem. Soc., V. 84-10, 1984, PP. 548-561