GB777892A - Improvements in the electrolytic production of metallic titanium - Google Patents

Abstract

777,892. Electrodeposition of titanium from fused salt bath. NEW JERSEY ZINC CO. June 14, 1955 [July 6, 1954], No. 17056/55. Class 41. In the cathodic deposition of titanium from a molten salt bath comprising at least one alkali metal or alkaline earth metal halide together with a chloride of titanium having a valency below 4, with simultaneous anodic evolution of chlorine, the anode and cathode are arranged so that without the interposition of a barrier the evolved chlorine rises in the portion A of molten salt between the anode and the adjacent surface of the cathode without entering the portion B of molten salt in contact with the remote surface of the cathode, and are sufficiently close to permit electrolytic depletion of the titanium content of the body A at a rate faster than can be replaced by diffusion from the rest of the molten bath to which titanium tetrachloride is supplied, the diffusion of titanium chloride into the portion A is retarded by restricting the area of the passage joining the two portions of the molten bath, and electrolysis of the titanium chloride is effected at a voltage high enough to maintain depletion of the titanium content of the portion A and to develop a back E.M.F. of at least 2.6 volts but insufficient to effect decomposition of any of the non-titaniferous components of the bath, i.e. not more than 3.4 volts. As shown, the anode 12 may be a rod and the cathode 13 may be a surrounding concentric tube which extends below the level of the anode and may have at its lower end an inwardly projecting flange 16 and is joined at its upper end to a non-corrosive tube 14, e.g. of glass, extending above the level of the bath. Alternatively the anode may be a tube concentrically surrounding the cathode tube which has an annular opening in its lower end. In an arrangement using sets of flat electrodes, the anodes may be arranged between pairs of cathodes, the remote surfaces of cathodes of successive sets being adjacent. Typically for a bath temperature of 560‹ C., the applied voltage varies between 3.8 and 4.3 volts.