GB744396A - Process for the preparation of substantially pure titanium metal - Google Patents

Abstract

744,396. Electrolytic production of titanium. NORTON GRINDING WHEEL CO., Ltd. Oct. 5, 1953 [Oct. 4, 1952], No. 27224/53. Class 41. Pure titanium is produced as a powder by electrolytic deposition in a cell containing one or more fused halides, preferably chlorides, of lithium, sodium, potassium, magnesium, calcium, and aluminium, and titanium carbide isolated from the cathode, e.g. as the anode. preferably the titanium carbide is in powder form in a cup surrounding the anode but it may be a sintered rod forming the anode. The cell is run at 500-600‹ C. and argon is passed continuously through the cell while chlorine may also be passed continuously to prevent deposition of the metals of the halides, especially magnesium, calcium, and aluminium which are difficult to remove from titanium. If desired powdered titanium carbide may be converted to titanium tetrachloride by passing chlorine into the heated cell before electrolysis. As shown, the cell housed in a container 22 packed with heat insulating material 31 and surrounded by an electric heater 28 comprises a tubular cathode 1 of titanium, nickel, or stainless steel closed at the lower end and screwed at the upper end into a steel coverplate 14 resting on an asbestos board 21 forming the lid of the container. The plate 14 carries a threaded steel plug 13 in which rests a ceramic cap 10 supporting a porous ceramic tubular partition 3 which is gripped by an asbestos washer for the plug 13 and from which depends a porous cup 4 containing powdered titanium carbide. A hollow carbon anode 7 surrounded for most of its length by a non-porous ceramic tube 8 passes through the cap 10, anode and tube being supported by releasable collars resting on the cap. Argon is passed into the cell through the tube 50 and chlorine is supplied through the hollow anode, a slow leak occurring around the cap 10. If chlorine is supplied continuously the top of the cell may be modified to collect and re-cycle the gas. A tube 57 is provided in the casing for a thermoelectric thermometer. The ceramics used may be different forms of alumina. If a sintered titanium rod is used as the anode, the sleeve 8 and the cup 4 may be omitted. When deposition of titanium is complete and before the melt has set the plug 13 and its associated assembly is replaced by a similar plug carrying an airtight cap through which a siphon tube passes so that by increasing the argon pressure the bulk of the liquid salt may be drawn off. When the mixture of halides and titanium in powder form has set it is scraped out and the titanium is freed from the halides either by vacuum distillation in the case of lithium, sodium, and potassium halides or by organic solvents in the case of magnesium, calcium, aluminium, and lithium halides. The resulting titanium sponge metal is consolidated into ingots by heating in an argon atmosphere and casting into graphite moulds or pressing into blocks.