Patent GB-637579-A (GB)
Title: Improvements in or relating to fused salt electrolytic cells
IPC: C25C3/20
Filed: 1946-08-29
Abstract: 637,579. Fused electrolyte apparatus. FERRAND, L. Aug. 29, 1946, No. 25924. Convention date, June 30, 1942. [Class 41] An apparatus for automatically controlling the operating conditions of electrolyzing a substance, e.g. alumina in the production of aluminium, dissolved in a fused salt bath in a cell having a fixed sole, comprises a plurality of anodes having means for separately adjusting the vertical position of each end of each anode by means of a motor which is controlled in response to variations in voltage between the terminals of the cell to raise or lower the anodes to adjust the said voltage to lie between predetermined limits, and means whereby when an abnormal increase in the said voltage occurs, due e.g. to " anode effect," the anodes are caused to oscillate transversely and prevent any vertical adjustment of the anodes whilst the abnormal condition exists. There may be associated with each anode means such as a mercury switch, which when the anode assumes a non-horizontal position starts the motor at the lower end of the anode to lift that end until the anode is again substantially horizontal to obtain equal current distribution throughout the anode. Furthermore, each anode may be associated with its own relay which responds to an excess current through the anode to raise both ends of the anode simultaneously to reduce the current flow. To maintain the temperature of the bath substantially constant, the voltage across the bath and the current through the bath are maintained substantially constant and the voltage controlling means are rendered effective for alternate periods of time, e.g. 3 minutes with the current controlling means which are rendered effective, e.g. for two-minute periods. The anodes are suspended from horizontal bars which are rotated by electromechanical means, one example of which is indicated in Fig. 3 and comprises a cam P which is rotated at a uniform speed by shaft X and is so shaped as to impart a uniformly variable straight line motion to the right and left driving rods B1, B2 to which the anode oscillating bars A are pivotally secured, the weight of the anode possibly with addition of loading springs, retaining the rod B1 or B2 in contact with the cam P. Such oscillation of the anode may be utilized to feed alumina to the cell, e.g. through a valve (Fig. 5) operated from the shaft X. When continuous feed is desired the valve ,remains stationary and is adjusted open for small feed. Specification 434,001, [Group XI], is referred to. The Specification as open to inspection under Sect. 91 describes hydraulic mechanism for oscillating the anodes, the mechanism being operated by electromagnetic valves under the control of the relay responsive to the sudden increase of voltage due to " anode effect." Also an alternative method of feeding the alumina to the fused bath is described. In this method the anodes of elongated form are juxtaposed in groups of three as shown in Fig. 5 (Cancelled), so as to provide a divided bottom surface and a concave top surface in which the alumina fed from above when the anode is in its normal at rest position will collect to fall therefrom during oscillation, the alumina being thereby heated up before it is poured into the bath. This subject-matter does not appear in the Specification as accepted.