Patent GB-763308-A (GB)
Title: Production of titanium tetrachloride and composition for use therein
IPC: C22B34/12
Filed: 1954-09-28
Abstract: <PICT:0763308/III/1> The production of titanium tetrachloride by fluidizing titanium dioxide-containing material with an upward stream of chlorine or chlorine-containing gases at 700 to 950 DEG C., preferably 750 to 900 DEG C., in the presence of a solid carbonaceous reducting agent, is characterized in that particulate agglomerates of said titanium dioxide - containing and carbonaceous material with an inorganic bonding agent are employed, substantially all particles of which lie between 8 and 200 mesh (U.S.S.), said agglomerates comprising at least 1.5 times the stoichiometric amount of carbonaceous solid reducing agent to react with the oxygen in said oxide to form carbon dioxide, and having a chlorine reactivity a60, defined hereinafter, of 45-95 per cent, preferably 50 to 80 per cent. The residue is withdrawn from a point above the entry of the agglomerates, which are preferably fed to the lowest portion of the reaction bed, e.g. in suspension in the chlorinating gas and withdrawn from the top thereof, though intermediate feed and withdrawal is permissible.  Suitable diluents for the chlorine, if used are nitrogen, argon and carbon dioxide (hydrogen-containing gases should not be used) and the concentration of chlorine therein may be 75 or even as low as 50 mol per cent.  The gas should be introduced at 0.1 to 1.5 feet per second and preferably at 0.2 to 0.8 feet per second.  The agglomerates may be prepared using as the titanium-containing material a titanium slag resulting from treatment of ilmenite for recovery of iron generally containing iron, calcium, magnesium, aluminium and silicon oxides and 60 to 80 per cent of titanium dioxide (examples given), ilmenite, rutile and such minerals as euxenite, polycrase, aeschynite, blomstrandine, risorite, wilkite, hainite, astrophyllite, delorenzite, keilhauite, knopite, lorenzenite and yttrocrasite; as the carbonaceous component, petroleum coke, ordinary coke, hard coal, charcoal or other sources of carbon, preferably not containing appreciable quantities of hydrogen can be used; and as the binder, glassy, high melting point materials such as alkali metal silicates, phosphates such as sodium and potassium ortho-, meta-, pyro- and poly-phosphates and aluminium phosphates, and hydroxides such as sodium and potassium hydroxide, may be used. A number of organic binders is specified, but these give unsatisfactory results.  The preferred agglomerates are prepared by separately comminuting a material containing at least 60 per cent by weight of titanium dioxide so that at least 80 per cent by weight passes a 200 mesh (U.S.S.) screen and a carbonaceous solid so that 80 per cent by weight passes a 140 mesh (U.S.S.) screen, mixing the particles so as to provide at least 1.5 times the amount of carbon to convert the oxygen of the titanium to carbon dioxide, forming an agglomerate with sufficient aqueous sodium silicate (preferably having a silica/sodium oxide ratio of 2 to 4) to provide 5 to 15 per cent, preferably 6 to 12 per cent by weight of sodium silicate based on the weight of the solids, drying the agglomerate and if necessary comminuting to provide particles of which substantially all will pass a 10 mesh screen and at least 70 per cent by weight lie between 20 and 140 mesh (U.S.S.) screen. Details are given of agglomerate-formation: it may involve a final flash-roasting at 850 DEG C.  The chlorine reactivity a60 is defined as the per cent extraction of titanium obtained during 60 mins. by passing 50 grams per hour of a mixture of 5 mol per cent of chlorine in carbon dioxide through 1 gram of solid particles at 800 DEG C. at a uniform rate. It is determined for the purposes of the invention by passing the dilute chlorine through transparent tube 13 (Fig. 1) into a mass of agglomerate in fluidizing chamber 11.  A plug 12 prevents the escape of solids, but titanium tetrachloride and other gases pass out through tube 23 for condensation and analysis.  A thermocouple 21 indicates the temperature which is maintained at 800\sB2 DEG C. by means of heating coil 15 surrounding an enclosure 14 of transparent material, reflector 19 assisting in maintaining uniformity of temperature. Observation is made through opening 20.  If it is not possible to determine the reactivity in this apparatus by reason of physical degradation of the particles, they are unsuitable for use in the process.ALSO:Particulate agglomerates of titanium dioxide-containing material and a solid carbonaceous reducing agent with an inorganic bonding agent are employed in the production of titanium tetrachloride substantially all particles of which lie between 8 and 200 mesh (U.S.S.), said agglomerates comprising at least 1.5 times the amount of carbonaceous solid reducing agent stoichiometrically necessary to react with the oxygen in said oxide to form carbon dioxide, and having a chlorine reactivity  60 (defined in the Specification) of 45-95 per cent, preferably 50 to 80 per cent.  The agglomerates may be prepared using as the titanium-containing material a titanium slag resulting from treatment of ilmenite for recovery of iron (generally containing iron, calcium, magnesium, aluminium and silicon oxides and 60 to 80 per cent of titanium dioxide (examples given), ilmenite, rutile and such minerals as euxenite, polycrase, aeschynite, blomstrandine, risorite, wikite, hainite, astrophyllite, delorenzite, keilhauite, knopite, lorenzenite and yttrocrasite; as the carbonaceous component, petroleum coke, ordinary coke, hard coal, charcoal or other sources of carbon, preferably not containing appreciable quantities of hydrogen can be used; and as the binder, glassy, high melting point materials such as alkali metal silicates, phosphates such as sodium and potassium ortho-, meta-, pyro- and poly-phosphates and aluminium phosphates, and hydroxides such as sodium and potassium hydroxide, may be used. A number of organic binders is specified, but these give unsatisfactory results.  The preferred agglomerates are prepared by separately comminuting a material containing at least 60 per cent by weight of titanium dioxide so that at least 80 per cent by weight passes a 200 mesh (U.S.S.) screen and a carbonaceous solid so that 80 per cent by weight passes a 140 mesh (U.S.S.) screen, mixing the particles so as to provide at least 1.5 times the amount of carbon to convert the oxygen of the titanium to carbon dioxide, forming an agglomerate with sufficient aqueous sodium silicate (preferably having a silica/sodium oxide ratio of 2 to 4) to provide 5 to 15 per cent, preferably 6 to 12 per cent by weight of sodium silicate based on the weight of the solids, drying the agglomerate and if necessary comminuting to provide particles of which substantially all will pass a 10 mesh screen and at least 70 per cent by weight lie between 20 and 140 mesh (U.S.S.) screen. Agglomerating processes referred to in examples involve (1) the use in sequence of a jaw-crusher, an attrition mill and a continuous ball mill with attached air-classifiers, for separately obtaining the solid constituents in suitable sizes; after blending, mulling with aqueous binder and drying the agglomerate was crushed in a jaw-crusher, coarse ground in an attrition mill and finally flash-roasted; (2) the solid constituents were crushed in a cone-crusher and milled in a continuous ball-mill having a closed circuit air-classifier; they were then mulled with aqueous binder in an edge-runner pan mill, passed to a granulator, dried, and classified, oversize particles being recycled via a roll-crusher to the classifier and undersize particles being recycled to the edge-runner pan mill.  Preferred particle size ranges are detailed.  A different kind of process for producing the agglomerates referred to comprises forming a thin film of solids and binder, drying and breaking up by passage through rollers. p