GB903426A - Electrolytic production of metal hydroxide - Google Patents

Abstract

903,426. Producing metal hydroxides by electrolysis. ROLLER, P. S. Nov. 17, 1958, No. 36969/58. Class 41. A method of producing insoluble metal hydroxide, e.g. of aluminium, iron, copper, silver, zinc or magnesium, comprises immersing metal electrodes in a suitable electrolyte, passing an electric current between the electrodes, and resiliently displacing the soft gel film which is formed on the electrodes before the film has set and during passage of the current. The film may be displaced by ultrasonic vibrations in the electrolyte. An apparatus comprises electrodes 11, 12, one face of each of which is contacted by a pliable, preferably flexible, e.g. rubber, wiper 17 secured to a member 16 mounted on a rotatable shaft 19. Direct current from a source 26 is delivered to the cell and the voltage is periodically reversed by a switch 30. Each period of electrolysis in one direction is followed by an equal period of depolarization during which a switch 29 is opened and a switch 38 closed to short-circuit the electrodes 11, 12. The switching operations may be automatically carried out. In a modification, the wiper comprises a gum rubber tube fitted over the member 16. The apparatus may include a plurality of alternating electrodes 11, 12, or two cells, each having one pair of electrodes 11, 12 may be employed, the switching operations being arranged so that one cell is depolarizing when the other is being subjected to electrolysis, and vice versa. It is stated that the wiper may be reciprocated over the electrode faces, but no details are given. Where the anode is liable to be anodized, the oxide film is removed at intervals by a solvent, e.g. a 1 to 5% HC1 solution containing an inhibitor of metal dissolution, e.g. 0.1% of hexamethylene tetramine.