GB780785A - Electrolytic cell - Google Patents

Abstract

780,785. Fused-electrolyte cells. NORTON GRINDING WHEEL CO., Ltd. Sept. 22, 1955 [Oct. 12, 1954], No. 27059/55. Class 41. An apparatus for extracting metal (or boron) from the carbide thereof comprises a gas-tight cell 1, e.g. lined with a graphite cup 51, for containing a molten electrolyte, e.g. a eutectic mixture of lithium chloride and potassium chloride, an anode, e.g. a cup 50, of the metal carbide immersed in the electrolyte, the metal being chosen from the group consisting of titanium, vanadium, chromium, zirconium, niobium, molybdenum, hafnium, tantalum, tungsten and boron, a cathode 18, preferably of the metal being extracted, immersed in the electrolyte, means for maintaining an inert atmosphere in the cell 1, and means for heating the electrolyte, e.g. an electric resistance 38 wound on a cylinder 36 of sintered. alumina and cemented at 40. The cell 1 has a head 3 to which is secured a head 5, a sealing ring 13 intervening, cooling water being passed through the heads 3, 5 between pipes 8, 9 by a rubber tube 12. An inert gas, e.g. argon, is passed into the cell 1 between pipes 24, one of which includes a needle valve to maintain pressure in the cell 1 at 1 to 2 inches of mercury. The cathode 18, which may be hollow and contain a thermocouple 19, 20, is adjustably supported on a screw stud 57 by a clamp 55, and enters the cell 1 in a gas-tight manner by means of an insulating bushing 17, a ring 21 and rubber tubing 22 sealing the openings between the bushing 17 and the exterior of the cell. Electrical connection to the cathode 18 and anode 50 is at 26 and 27 respectively, and the anode may be replaced by removing a plug 63 in a drain 2 in the cell 1 and forcing the cups 50, 51 upwardly, the head 5 being previously removed. A steel cylinder encloses the cell 1 and heating element 36, 38, 40 and is insulated therefrom by fuller's earth 41. Instead of a cup anode, four separate vertical plate anodes arranged at right angles may be employed, each standing clear of the graphite cup, and four rod cathodes may be employed with this arrangement. In all arrangements, the anode should be large enough to enclose at least 80 per cent of the unmasked area of the cathode, that is the area which is not shielded in a direction normal to its surface by another cathode area. Various examples employing a titanium carbide anode are described. The anode cup is filled with electrolyte, the apparatus assembled, the electrolyte heated, e.g. to 900 ‹C. to 1000‹ C., and water and argon supplied to the cell. The current is then applied, e.g. at 3.4 volts, to provide a cathode current density of 164 amps. per square decimetre. A current density of 246 amps. per square decimeter, is mentioned. The electrolyte may be any halide of an alkali metal or of an alkaline earth metal or of a mixture thereof.