Patent GB-712742-A (GB)
Title: A new or improved method for the electrolytic production of titanium metal
IPC: C25C3/28
Filed: 1952-10-03
Abstract: 712,742. Electrolytic production of titanium. TITAN CO., Inc. Oct.. 3, 1952, [Oct. 5, 1951.] No. 24883/52. Class 41. A continuous method for electrolytically producing titanium metal comprises providing a fused salt electrolyte in a cell having an anode, a solubilization cathode and a deposition cathode, and means for separating chlorine released at the anode from contact with the cathodes, introducing titanium tetrachloride in proximity to the solubilization cathode, meanwhile passing I to 2 faradays of current between the solubilization cathode and the anode for each mol of titanium tetrachloride introduced to form titanium dichloride and trichloride in proximity to the solubilization cathode, transferring the titanium dichloride and trichloride without contact with the anode through the electrolyte to the vicinity of the deposition cathode, where metallic titanium is deposited by passing 2 to 3 faradays of current between the deposition cathode and the anode for each mol of tetrachloride introduced, and maintaining the molality of the trichloride not greater than 2.O and the molality of the dichloride not less than O.5 in proximity to the deposition cathode. The molality of the trichloride in proximity to the deposition cathode may be not greater than O.25 times the molality of'the dichloride, and the molality of the dichloride may be not less than O.1. The molality of the dichloride in proximity to the solubilization cathode may not be less than O.1, and the current density in amperes per square centimetre on this cathode may be not more than the numerical molality of the trichloride. A current of 4 faradays per mol of titanium trichloride introduced may be passed, being evenly divided between the two cathodes. The electrolyte may be a halide of an alkali metal or of an alkaline earth metal (including magnesium) or a mixture of such halides; particularly a eutectic mixture of strontium chloride and sodium chloride. The process may be performed in a heated cell container 12 (Fig. I) partially filled with fused electrolyte 14 in which are suspended cathodes 16 and 17 of metal such as tantalum, and a graphite anode 18 surrounded by a porous diaphragm 19. A porous diaphragm 20 surrounds the deposition cathode 17, but may surround the solubilization cathode 16 instead. A cover 21 has means 22 for admission of an inert gas, such as argon or helium. A pipe 23 carries away chlorine released at the anode, and an impervious sleeve 25 insures complete separation of the chlorine. Titanium tetrachloride is added through a tube 24 and metallic titanium is deposited on cathode 17. In another apparatus (seen in plan in Fig. 5), an anode 33 is separated from cathodes 34 and 35 by porous diaphragms 36 and 37. Titanium tetrachloride is introduced by means of tubes 38 near the solubilization cathode 34, and the melt containing dichloride and trichloride is pumped through a passageway 39 by a pump 40 to the chamber surrounding the deposition cathode 35. The partly depleted solution is pumped back to the chamber surrounding the solubilization cathode 34 along a passageway 43 by a pump 42. The diaphragms in the cells may be of sintered alumina passing particles of a maximum size between i and 20 microns. U.S.A. Specification 2,205,854 is referred to.