PROCESS FOR THE MANUFACTURE OF A RUTILE PIGMENT BY REACTING TITANIUM TETRACHLORIDE WITH OXYGEN OR GASES CONTAINING OXYGEN

摘要

Rutile TiO 2 pigment is produced by reacting gaseous TiCl 4 with 0 2 in a reaction chamber, and cooling the reaction products with cold inert gas in an immediately adjacent mixing chamber, the cold gas being introduced into the end remote from the reaction chamber and in countercurrent to the reaction products. Initial contact with the cold gas, which may enter at room temperature, and by then is at 800- 1250 C., prevents further particle growth but allows rutilization to continue. The cold gas may be air, N 2 , C0 2 , C1 2 , or cooled product gases freed from TiO 2 . It may be introduced at one or several points, e.g. at 400 m.3 per 500 kg. TiCI 4 . Preferably, the reactants are introduced downwards, the cold gas upwards, and the gas mixture withdrawn either through a pipe concentric within the cold gas inlet pipe (Fig. 4) or sideways from the middle of the mixing chamber (Figs. 1-3), coarse TiO 2 being removed from the bottom. The cold gas inlet may have a conical distributer (Fig. 2) or guide vanes which impart spiral flow (Fig. 3). The mixing chamber may be cylindrical or conical, and of circular or square cross-section. In examples, TiCI 4 containing AlCl 3 at 350 C., O 2 at 250 C., and CO (auxiliary) at room temperature are used, and the products withdrawn at 730 C. The TiO 2 produced contains less than 1 % anatase.