Electrolytic cell

853,366. Electrolytic apparatus. UNITED STATES BORAX & CHEMICAL CORPORATION. June 5,1959 [June 17,1958], No. 19246/59. Class 41 An electrolytic apparatus comprises a receptacle constituting the cathode, a removable main anode, a similar receptacle adapted to be clamped to the first in mouth-to-mouth register after removing the main anode, and means for inverting the clamped receptacles to transfer the electrolyte to the second receptacle prior to removal of the first receptacle for recovery of the electro-deposited material. As shown (Fig 2) a cell 3 has a removable main anode 1; a subsidiary anode 2, attached to a ring 7 which may be placed on an annular insulator 8 around the mouth of the cell has an upwards-extending portion 21. A similar cell 31 (Fig. 1) may be clamped to the first, rim to rim. so that the part 2 of the subsidiary anode extends thereinto. The assembly is then swung about the trunnions 51 so as to invert the receptacles, the cell 3 is removed for recovery of electrodeposited material and the main anode is replaced in the cell 31 to continue the electrolysis. Means such as a pipe 13 (Fig. 2) may be provided to maintain an atmosphere of inert gas during the changeover. A sufficient current is passed through the subsidiary anode to provide cathodic protection of both receptacles against corrosive electrolytes while the main anode is withdrawn. The receptacles may be iron pots, and the main and subsidiary anodes may be graphite rods. The process is especially applicable to electrolysis of fused salts, and examples are given of the production of boron from a fused mixture of potassium chloride, potassium fluoride and boron trioxide, and of the production of calcium boride from a fused mixture of calcium chloride, calcium oxide and boron trioxide. The mixture of compounds is fused by heating the cell in a crucible or furnace, or by resistance or induction heating; a small current may be passed through the main anode during fusing to provide cathodic protection of the cell.