RI 4059 Reduction of Magnesium Chloride by Calcium Carbide

This method is similar to the reduction of dolomite by ferrosilicon, in that it does not require the direct use of electrical energy; like ferrosilicon, the calcium carbide must be produced in an electric furnace, so that the reducing agent in both processes may be considered in some respects as “stored” electrical energy. The reduction of magnesium chloride by calcium carbide is exothermic, takes place rapidly at ordinary pressure and at relatively low temperatures, and can be carried out in ordinary steel equipment, whereas the reduction of dolomite by ferrosilicon and the carbothermic reduction of magnesium oxide are endothermic, require high temperatures, and present serious problems with respect to materials of construction. Because of its apparent simplicity and other advantages, the Bureau of Mines has briefly investigated the reduction of magnesium chloride by calcium carbide. Published data on the reduction of magnesium chloride by calcium carbide are meager. Matignon states that reduction is fairly rapid at 1,200º C. Matsuura claims that magnesium chloride is not reduced by calcium carbide at atmospheric pressure and 800º C; however, by keeping the pressure under 10 mm. of mercury he was able to obtain small globules of magnesium at 800º C.