Electrolytic Production of Calcium Metal.
Proceeds 7th Int'l Symp on Molten Salts Electrochem Soc 90-:588-599
The U.S. Bureau of Mines developed an alternative electrochemical process for the production of calcium metal. The current industrial practice is costly, complex, and inefficient. The Bureau method involves electrowinning a calcium-tin alloy followed by electrorefining to produce calcium metal. In the electrowinning cell, calcium chloride was fed to a potassium chloride-calcium chloride electrolyte. The calcium was electrowon at 650 deg c into the pure molden tin cathode until the cathode contained 7.5 Wt pct ca. Current efficiency for electrowinning averaged over 90 pct. The resulting tin-calcium alloy served as the anode for the electrorefining cell which employed a calcium chloride-calcium fluoride fused salt as the electrolyte. Calcium metal was electrorefined at 850 deg c with a current efficiency of 85 pct based on calcium metal recovered. The calcium metal analyzed 99.2 pct, which is purer than commercially produced calcium.
Proceeds 7th Int'l. Symp. on Molten Salts. Electrochem. Soc., V. 90- 17, PP. 588-599