GB736852A - Improvements in or relating to the production of metals or alloys by reduction of metal halides - Google Patents

Abstract

736,852. Producing metals and alloys. NATIONAL SMELTING CO., Ltd., and DERHAM, L. J. Aug. 24, 1951 [Sept. 13, 1950], No. 22506/50. Class 82 (1). Metals or alloys are produced by reacting in a heated heatinsulated vessel the vapour of at least one metal halide and the vapour of at least one metallic reducing agent, the major part of the necessary heat for maintaining the reaction being provided by the exothermic reduction of the halide, the metal or alloy produced being deposited free from halide on the base or walls of the vessel while the product halide of the reducing metal is removed in vapour form. In the reduction of chlorides a metallic reducing agent whose chloride boils above 1000‹ C. may be used, the temperature of the reaction vessel being maintained above the boiling-point of the reducing metal chloride. The additional heat required to maintain the reaction may be provided by the sensible heat introduced in the reactants. Among the halides which may be treated are the chlorides of Ti, Zr and Be, mixtures of chlorides of Ti and Zr or mixtures of chlorides of Ti or Zr with chlorides of Fe and Cr or with chloride of Si and/or Al. As reducing agents there may be used Mg, K or Na. When sodium is used it is preferably used in a slight stoichiometric excess the vapour being supplied at substantially its normal boiling-point and a slight positive pressure relative to the atmosphere. In the reduction of Ti chloride with K the chloride may be used with Cl gas and a slight stoichiometric excess of K which by reaction with the Cl provides extra heat. A small amount of oxygen or oxygen diluted with argon or nitrogen may be introduced into the reaction vessel through a separate entrance. The apparatus shown in Fig. 2 has carbon walls 22 and a carbon lid 23 through which pass inlets 24 and 25 for chloride vapour and metal vapour respectively. An outlet 28 is provided for removal of the vapour of chloride of the reducing agent which is formed in the reaction. A carbon floor 26 is provided with a depression 27 in which molten metal can collect. The vessel is first heated by induction coil 29, the heat is then cut off and the reagents introduced. Spongy or powdery metal forms as a layer 31 on the inner walls of the vessel. This metal, when sufficient has been formed, is melted by induction heating and runs into the depression 27. The apparatus shown in Fig. 3 comprises an inverted bottle-shaped vessel 33 with neck 35, inlets 37 and 38 for the reagents and an outlet 39 for vapour of chloride produced by reaction. A solid Ti plug 46 is inserted in the neck 35, the vessel is then heated to about 1600 ‹ C. by means of carbon resistors 41 and 42. Na vapour mixed with less than 1 per cent by volume of argon is introduced through inlet 37 and TiCl4 vapour through 38. Ti forms as a layer 47 on the walls of the vessel and 47a around the outlet tube 39. Most of the Ti flows down as molten metal and accumulates in the neck 35 above the plug 46. Induction coil 45 is then switched on, the plug and accumulated metal is melted and falls into mould 49 which is maintained in an atmosphere of argon.