Abstract: Directed to the electrolytic purification of molten magnesium chloride cell feed and to a covered cell design therefor wherein preferably a plurality of bipolar electrodes are employed. A current density of about 0.8 to about 1.5 amperes per square inch D.C. is employed, flow of the electrolyte through the cell proceeds in a non-turbulent manner through flow passages in the electrodes, and the solid impurities deposited electrolytically are removed periodically by mechanical action.

Abstract: Magnesium oxide is chlorinated in molten impure magnesium chlorine with chlorine gas by adding ferrous chloride to magnesium chloride brine, drying the brine, adding a mixture of calcined petroleum coke and charcoal to the dried brine, melting the product and chlorinating the formed melt. Ferrous chloride is added in amounts sufficient to provide from about 1.0% to 2.2% by weight of iron in the dried product. A highly reactive carbon source is added in amounts of from about 0.8 to 2.3% by weight and a carbon source that is less reactive than the highly reactive carbon source is added in amounts ranging from about 0.8 to 2.3% by weight of dried brine. Iron levels in the magnesium chloride melt may be adjusted upwardly by addition of a mixture of iron oxide and charcoal.A melt cell characterized by side entry electrodes disposed at angles from 40.degree. to 50.degree., an arched roof configuration, and an improved electrode refractory and ceramic sleeve construction is used to chlorinate the magnesium.

Abstract: Spray-dried magnesium chloride salt containing minor amounts of impurities in the form of oxygen containing compounds including metal oxides and in particular particulate magnesium oxide, hydroxyl groups, and the like, is purified by forming a molten bath of said magnesium chloride salt and chlorinating the molten salt in the presence of carbon and an iron chloride complex.