Review―Smelting and Refining Methods of Calcium Metal

Major applications of calcium metal are for metallurgy such as a calcium-cored wire for deoxidation and desulfurization in steel making process as well as a reducing agent for nonferrous metals including rare earth metals. The most common production method is thermal reduction of calcium oxide by aluminum metal as a reducing agent. An alternative method is electrolysis of molten calcium chloride in which calcium is obtained in the form of a liquid alloy of calcium and copper at the cathode. Purifications of calcium metals thus obtained are performed by vacuum distillation to eliminate the impurities to acceptable levels. Calcium produced by the former method contains aluminum and magnesium as major impurities, whereas that by the latter contains metal chlorides, separately coming on to the market by the difference in their impurities.