Patent GB-838372-A (GB)
Title: Electrolytic method and means for production of titanium metal
IPC: C25C3/28
Filed: 1957-04-10
Abstract: 838,372. Electrolytic production of titanium. NATIONAL LEAD CO. April 10, 1957 [April 25, 1956 ; May 2, 1956], No. 11793/57. Class 41. In the electrolytic production of titanium from a fused bath of one or more of the halides, preferably chlorides, of the alkali metals, alkaline earth metals, and magnesium with the use of a perforated basket-like cathode into the lower part of which is introduced titanium tetrachloride at a rate synchronized with the electrolyzing current so that the tetrachloride is reduced to metal and the bath outside the cathode is maintained free from dissolved titanium values, the current-to-feed ratio is maintained between 5 and 7 Faradays per mol. of titanium tetrachloride introduced, the cathode current density is kept between 200 and 550 amps./sq. ft. and the time of run is controlled so as to form a porous adherent mass of titanium on the interior surfaces of the basket-like cathode. Typically the bath is maintained between 375‹ and 950‹ C. and the concentration of reduced titanium chlorides within the basketlike cathode is not permitted to exceed 1% calculated as titanium. A suitable cell for carrying out the process has a lining of highpurity alumina brick 14 within a metal skin 12, e.g. iron, which is itself surrounded by insulating brick 13 and an outer metal shield 11, e.g. of iron also. Argon or helium is fed to the cell at 59 through the cell closure and is withdrawn together with anodically evolved chlorine through a port 57 (Fig. 1, not shown) in the closure. The cathode basket 39 is of rectangular cross-section and is disposed with its two opposed perforated faces 38 between opposed plate anodes 16. Vertical heaters 17 are disposed in shafts communicating with interior 15 of the cell. A nickel feed-pipe 40 for the titanium tetrachloride is carried upon the inner of two nickel tubes 47, 48 between which is disposed an iron tube 45 carrying the cathode basket 39, to which all three tubes are welded, and bearing a flange 46 to which the cathode lead 55 is attached. The flanges of the tubes are separated by insulating gaskets and the whole is shrouded by a graphite sleeve 52. Adjacent the top plate of the basket the nickel tube 40 is connected to a titanium tube 43 having a graphite lining 44 so that the titanium deposit does not become contaminated with nickel. The tube assembly is attached to a frame 37 which normally makes a gas-tight seal via low melting-point metal 22 with the cell closure. To this frame 37 is secured a rod 34 by which the tube assembly and cathode basket may be withdrawn from the cell into a cooling hood 27, when this is lowered into the chaindotted position to form a gas-seal with the closure by means of low melting-point metal 24, the rod 34 passing through the top of the hood (Fig. 1, not shown). The hood which has a cooling water jacket 30 is fed at 35 with argon which passes out through a port in the top of the hood. In a simpler cell, the titanium tetrachloride feed tube carries the cathode basket directly and is supported directly from a more rudimentary cell closure, while the electrolyte heaters are disposed on the bottom of the cell. Reference is also made to the use of a cathode basket with only one perforated wall. Reference has been directed by the Comptroller to Specifications 678,807, 734,094 and 777,829.