GB768867A - Improved production of titanium tetrachloride - Google Patents

Abstract

Briquettes comprising titaniferous material containing at least 20 per cent of TiO2 and 50-135 per cent by weight of carbonaceous material (with respect to said titaniferous material) of which 50-100 per cent is coking coal and the remainder noncoking coal, are coked at at least 600 DEG C., preferably 900-1000 DEG C. and chlorinated with chlorine at a temperature of 600-1000C. DEG maintained by utilizing the heat of reaction. As a result of this procedure the briquettes do not disintegrate during the reaction. Suitable titaniferous materials are ores such as rutile and ilmenite, concentrates and slags e.g. containing by weight at least 60 per cent TiO2, iron oxide (calculated as Fe) up to 20 per cent and lime up to 18 per cent (as CaO). The coking coal should preferably be of high fluidity, i.e. of 10,000 Giesler units or more: non-coking coals specified are anthracite, coke breeze and/or petroleum coke. It is preferred that the carbon content of the carbonaceous material in the briquettes be such as to provide 2-5 times that stoichiometrically necessary to chlorinate the titanium component with formation of carbon monoxide. The materials should be finely ground (the non-coking coal may be less fine) and suitable particle sizes are given; it is preferred to mix and densify the mixed constituents in an edge runner mill before briquetting. The latter may be performed by conventional means with the use of water only or with 3-8 per cent by weight of a carbonaceous binder such as spent sulphite liquir or pitch rather than with an argillaceous binder such as bentonite. Chlorination may be effected in a shaft furnace, preferably as a deep but narrow bed, to keep the temperature in the lower part of the range by radiation; the temperature may also be controlled by dilution of the chlorine gas or of the briquettes with inert substances, by varying the size of the ore or slag particles or of the briquettes, by introducing the chlorine separately at vertically spaced points in the charge, by varying the charging rates of reactants, by varying the ratio of preheated to cold briquettes in the charge and/or by choice of furnace insulation. In an example giving full details, the briquettes were placed in a steam drier prior to coking to avoid cracking in this process. The furnace was preheated by passing air through a 2 ft. bed of lump coal surmounted by the briquettes; when 700 DEG C. was reached the air supply was stopped, the coal discharged, further briquettes charged to a depth of over 8 ft. so as to bring the level of the charge above the gas exit level and chlorine charged at a rate sufficient to give an excess over that required to form FeCl3 without exceeding 2 per cent of chlorine in the exit gases; a jet of TiCl4 was used to cool the exit gases comprising TiCl4, SiCl4, VOCl3, FeCl3 and AlCl3 to form a TiCl4 slurry. The slurry was filtered (to remove iron chlorides), the filtrate treated conventionally to remove vanadium and then distilled to give pure titanium tetrachloride.ALSO:Briquettes suitable for chlorination to give titanium tetrachloride (see Group III) are prepared from a titaniferous material containing at least 20 per cent of TiO2, and 50-135 per cent by weight of carbonaceous material of which 50-100 per cent is coking coal and the remainder, if any, non-coking coal, and are coked at at least 600 DEG C. Specified titaniferous materials are rutile, ilmenite and slags produced by reduction of ilmenite in an electric furnace (the latter containing at least 60 per cent TiO2, up to 20 per cent Fe (as iron oxide), up to 18 per cent CaO, and magnesia); coking coals are preferably bituminous and having a Giesler fluidity of more than 10,000 units: non-coking coals may be anthracite, coke breeze and/or petroleum coke. The materials should be finely divided (details given) and preferably densified on an edge runner mill before briquetting with water or preferably with 3-8 per cent of a carbonaceous binder such as spent sulphite liquor or pitch. Pillow shaped briquettes 2 x 2 x 1 1/4 ins. may be made and coked at 900-1000 DEG C to give a structurally strong, porous material. An example is given, in which prior to coking the briquettes were placed in a steam dryer, to avoid cracking.