GB1520960A - Electrolytic production of metal - Google Patents

Abstract

1520960 Fused electrolyte cells ALUMINUM CO OF AMERICA 26 Nov 1976 [31 Dec 1975 (2) 25 Aug 1976 (2)] 49444/76 Heading C7B Metal is produced electrolytically by electrolyzing between anodic and cathodic surfaces a compound of the metal dissolved in a fused electrolyte, electrolysis being undertaken at a temperature such that molten metal is formed which is subsequently collected in a molten metal pad, the cathodic surface being an array of elements unconnected to the side walls of the cell and extending from the pad towards the anode such that the anode-cathode distance is not greater than 1“ in. In one embodiment, the array takes the form of cylindrical studs 10 extending from the molten pad 11 towards the anode 13 such that the distance x is not greater than 1“ in. The distance "y" separating the molten metal pad and the anode is preferably at least 2¢ in. The conductive cathodic crucible (e.g. graphite) is insulated from the anode by the refractory insulator 17 (e.g. Al 2 O 3 ). The elements may also have square or triangular cross-section. In another embodiment Fig. 3 (not shown) the elements take the form of a grate (23) supported on a post (24) which in turn is secured to the bottom of the crucible. Alternatively, the elements may be in the form of hollow bodies which contain molten material Fig. 5 (not shown). Thus, tubes (28) extend from the molten metal pad and end just short of the anode (29), with the ends of the tubes closest the anode being open and the tubes filled with molten metal; the tubes may or may not be of electrically conductive material. The cells are particularly useful for preparing Al, e.g. from NaF/AlF 3 /LiF melts containing Al 2 O 3 . Suitable cathode materials are the carbides, borides, silicides and nitrides of the transition metals of Groups IVa, Va and VIa of the Periodic Table; particularly TiB 2 (with or without BN addition); pyrrolytic graphite may also be used as cathode material.