GB776295A - Improvements in the chlorination of titaniferous ores - Google Patents

Abstract

<PICT:0776295/III/1> A process for chlorinating a titaniferous material at 600-1050 DEG C., preferably 850 to 1000 DEG C., in the presence of a reducing agent in a fluidized bed is characterized in that a portion of the bed is withdrawn, cooled and returned; and in that gaseous reaction products are removed from the bed, passed to a zone in which they undergo direct heat exchange with the fresh titaniferous material which is to be charged to the bed and are separated from said material, after such chlorination products are recovered from the gaseous products. The Specification refers to ilmenite, rutile and titanium oxide concentrates as the titaniferous materials; to solid carbonaceous reducing agents such as carbon, coal or coke, which may be charged into the bed in admixture with the titaniferous material in suspension in the chlorinating gas or may be charged separately; to gaseous reducing agents such as carbon monoxide; and as chlorinating gases to pure chlorine, chlorine diluted with nitrogen or carbon monoxide, the tail gases from oxidation of titanium tetrachloride by air and chlorine compounds such as carbon tetrachloride, sulphuryl chloride, sulphur monochloride and phosgene, the latter rendering an additional reducing agent unnecessary. In the embodiment illustrated, a finely ground mixture of carbonaceous reducing agent and titaniferous material (e.g. 1 part coke to 5 parts rutile or ilmenite by weight), are introduced from hopper A into line 2 in which it mixes with hot gases discharged from reactor B. The solids are separated in cyclone C and products (titanium tetrachloride and ferric chloride), are recovered from the gases emerging through line 15. The solids are passed via lines 3 and 4 into the reactor by means of the chlorine-containing gas entering through valve 25 so as to have a velocity e.g. of 1.0 to 10 feet per second in the reactor to maintain the solids therein in a fluidized state. The cooling is effected by withdrawing solids from the bed by line 5 and passing them by means of an inert gas (e.g. the uncondensable gas from the titanium tetrachloride recovery system) through line 6 and cooler D. This cooling may be supplemented by passing the preheated solids in standpipe 3 through the cooler F by means of an inert gas (e.g. said uncondensable gas) introduced through line 1611 or by cooling the solids between the cyclone C and line 4. It is preferred to allow the non-volatilizable materials and ash residues in B to accumulate to give a low titanium dioxide content of say 10 to 20 per cent, and remove said materials intermittently, but continuous removal is possible. The material may be removed via lines 6 and 7. If desired the reaction chamber may be preheated or the temperature maintained during the reaction by burning fuel therein, by introducing combustion products from an oil burner or other source through line 16, or by external heating, or by introducing air or oxygen to the reaction zone. Details are given of flow rates for gases and particle sizes; in examples the illustrated apparatus is used in one case and in another a long narrow silica tube is employed as reactor and the preheated solid reactants are added at the top through a long delivery tube.