GB722901A - Production and purification of titanium - Google Patents

Abstract

In a process of producing titanium (see Group II) the normally stable lower chlorides or bromides, especially the dihalides, of titanium are formed by the reaction of the corresponding tetrahalide vapour with titanium-bearing material whereby the vapours of the low halides are formed and can be condensed in a cooler zone. The lower halides are formed free from any impurities present in the titanium-bearing material and, if the unsaturated vapour of the tetrahalide is used, are also free from unreacted tetrahalide. Titania and carbon may be used instead of titanium-bearing material, thus forming a gaseous mixture of the lower titanium halides and carbon monoxide from which the lower halides are condensed. To ensure that the lower titanium halides are pure they are condensed onto an invert surface e.g. titanium or molybdenum. A suitable layer of titanium is formed on the surface of a refractory material, e.g. mullite, by the reaction of the lower halide just formed and the refractory material and the rest of the lower halide condenses on this. Similarly, if a graphite or refractory carbide condenser is used, a titanium carbide protective layer is initially formed. In one example, a stream of argon saturated with titanium tetrachloride vapour at 20 DEG C. (corresponding to a partial pressure of about 10 mms.) was passed over impure titanium (3-6 mesh) maintained at about 1050 DEG C. and contained in a graphite tube lined with molybdenum. The reaction products were passed into a cooler zone where titanium dichloride and smaller amounts of titanium trichloride and metallic titanium were condensed. In a second example, the tetrachloride partial pressure was 180 mms. and the condensate again consisted mainly of titanium dichloride with smaller amounts of titanium trichloride and metallic titanium. In further examples, titanium terabromide at partial pressures of about 5 mms. and 80 mms. was used with the impure titanium maintained at 1000 DEG C.ALSO:A process for producing titanium consists in leading the unsaturated vapour of titanium tetra-chloride or -bromide in an inert atmosphere, e.g. argon or hydrogen, at reduced pressure, over titanium-bearing material at elevated temperature to form the vapour of the corresponding lower normally stable halide (i.e. di- and/or tri-halide), passing these lower halide vapours to a cooled zone where they partly decompose into metallic titanium and tetrahalide vapour and partly condense, heating the condensate under a tetrahalide pressure lower than its decomposition pressure to convert it into metallic titanium and tetrahalide vapour, and using the tetrahalide vapour for further titanium extraction from the titanium-bearing material. The titanium-bearing material may be impure titanium, a titanium alloy or a titania-bearing material with carbon. The process may be worked continuously by passing the lower halide vapours, formed during the passage of the tetrahalide over the titanium-bearing material, alternately into one of two converters each of which in turn is cooled to condense the lower halide vapour and heated to convert the condensate into titanium and the tetrahalide. The tetrahalide may be circulated as vapour or may be alternately condensed and evaporated in more than one condenser. The surface upon which the lower halides condense may be of titanium or molybdenum or of an oxygen-containing refractory material, e.g. mullite, or graphite or a refractory carbide on which a protective layer of titanium or titanium carbide respectively is formed by the lower halides themselves.