GB734094A - A new or improved process for the production of refractory metals - Google Patents

Abstract

734,094. Electrolytic production of refractory metals. TITAN CO., Inc. Oct. 17, 1952 [Oct. 18, 1951], No. 26086/52. Class 41. A. method for the electrolytic production of refractory metal in an electrolytic cell having a cathode, an anode and a fused halide salt electrolyte comprises continuously introducing below the surface of the electrolyte a halide of the metal to be reduced, meanwhile concurrently passing electric current through the cell between the cathode and anode at a rate appropriate to the rate of metal halide addition so that the amount of current is sufficient to reduce the metal halide substantially directly to metal, the metal halide being added in juxtaposition to the cathode to contact the surface thereof. The refractory metal may be cerium, hafnium, thorium, titanium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum or tungsten. The electrolyte may be a halide or halide mixture of alklai or alkaline earth metals, including magnesium, particularly the chlorides; a low melting-point eutectic, such as a mixture of sodium chloride with strontium or magnesium chloride, is preferred. A cell, as shown in Fig. 1, may be used, which is heated by graphite electrodes 12 and has a cathode 14 and anode 15. Titanium tetrachloride is introduced by a conduit 16 terminating close to the bottom of the cathode 14. A barrier 17 extending beneath the surface of the molten electrolyte 13 separates the cathode from the anode. A vent 18 removes gaseous products from the anode section of the cell. Titanium metal 19 is deposited on the cathode 14. An alternative cathode 14A (Fig. 3) is a hollow tube of tantalum or nickel metal through which titanium tetrachloride gas is passed, a porous mass of titanium metal 20 being formed, having a hollow portion, and confining the reduction of the tetrachloride to the metal to the immediate vicinity of the cathode. In a modification the cathode is a hollow tube connected to and extending into a porous container or basket containing closely packed titanium metal particles also in contact with the tube. 4.5 to 5.0 faradays of electricity are passed for every mol. of titanium tetrachloride introduced. Slightly more than 5 faradays of electricity may be passed, when obtaining molybdenum from molybdenum pentachloride, for every mol. of pentachloride introduced, and slightly more than 4 faradays when obtaining vanadium from vanadium tetrachloride, for every mol. of tetrachloride introduced. A cathode current density of 1 to 6 amperes per square centimetre, such as 3 amperes per square centimetre, may be used. Specification 678,807 and U.S.A. Specification 2,205,854 are referred to.