| Abstract |
As part of its goal to help maintain an adequate supply of minerals to meet national economic and strategic needs, the Bureau of Mines, U.S. Department of the Interior, is investigating a fused-salt electrolytic procedure for producing zinc metal. A previous report described preliminary, small-scale work on the fused-salt electrolysis of ZnCl2. The present report covers a more detailed investigation of the properties of ZnCl2-alkali metal chloride electrolyte systems in relation to the production of zinc metal and also discusses electrolysis in large-scale, internally heated cells. The effect of composition on bath stability, current efficiency, cell voltage, and liquidus temperature was determined for the ZnCl2-NaCl-KCl, ZnCl2-NaCl-LiCl, and ZnCl2-KCl-LiCl electrolyte systems. An electrolyte composed of 38 mole-pct ZnCl2, 31 mole-pct NaCl, and 31 mole-pct KCl gave the best overall results. Sludge (ZnO) formation in the ZnCl2-NaCl-KCl, ZnCl2-KCl-LiCl, and ZnCl2-KCl systems was investigated during prolonged electrolysis. The ZnCl2-KCl-NaCl electrolyte showed the least sludge formation. A 1,500-amp cell was operated using the ZnCl2-NaCl-KCl electrolyte at 500C. Zinc metal was produced at the rate of 4.0 lb/hr with a current efficiency of 95 pct. |
