GB747772A - Process for production of manganese metal and chlorine - Google Patents

Abstract

747,772. Electrolytic production of manganese. OLIN MATHIESON CHEMICAL CORPORATION, [formerly MATHIESON CHEMICAL CORPORATION]. July 27, 1953 [July 28, 1952], No. 20759/53. Class 41. A process for the production of manganese metal and chlorine from manganese chloride comprises circulating an aqueous catholyte solution of manganese chloride and ammonium chloride through a cathode compartment of a cell divided by a diaphragm, circulating an aqueous anolyte solution containing a soluble chloride through an anode compartment of the cell, the soluble chloride comprising hydrogen chloride, an alkali metal chloride, or an alkaline earth metal chloride, passing a current through the cell and depositing manganese metal at the cathode and discharging chlorine gas at the anode. The catholyte is fortified with manganese chloride and recirculated to the cathode compartment. The catholyte may be prepared and fortified with pure manganese chloride and pure ammonium chloride, but the manganese chloride may be derived from a manganese ore, impurities being precipitated by addition of sodium sulphide or hydrogen sulphide and ammonia. Sulphur dioxide or sodium thiosulphate may be added to the catholyte to prevent oxidation of the manganese metal and to avoid formation of manganese dioxide. The anolyte may be a solution of hydrochloric acid or sodium chloride, and is refortified with acid or salt and recirculated to the anode compartment. When the anolyte contains sodium chloride, sodium ions accumulate in the catholyte, and effluent catholyte may be cooled to crystallize excess sodium chloride from the solution. The cell preferably comprises a plurality of anode and cathode compartments separated by diaphragms, which may be of " Vinyon " (Registered Trade Mark). The anodes may be of graphite and the cathodes may be of stainless steel or titanium. Stainless steel cathodes may be dipped in dilute sodium silicate solution before use to facilitate removal of manganese metal. Effluent chlorine gas is dried, such as by scrubbing with concentrated sulphuric acid, and may be compressed.