GB778706A - Apparatus for the production of metal oxides - Google Patents

Abstract

An apparatus for the production of oxide pigments by halide hydrolysis according to the process described and claimed in Specification 778,705 consists of a primary cylindrical reaction chamber having a diameter greater than its length, and in axial <PICT:0778706/III/1> <PICT:0778706/III/2> alignment therewith, a secondary reaction chamber having a diameter less than that of the primary chamber and the length greater than its own diameter. The halide to e hydrolysed is injected axially into the first reaction chamber and provision is made for the introduction of a mixture of a combustible gas containing hydrogen, and oxygen into the primary reaction chamber in a direction tangential to the walls thereof which mixture burns to form the water for the hydrolysis. In addition means are provided to inject an auxiliary mixture of combustible gas and air downstream from the point of introduction of the hydrogen/xyogen mixture. As shown in the Figure (Fig. 2), a heat insulated cylindrical reaction chamber 56 is formed in a refractory material 50 and is provided with a manifold 70 and pipes 60 whereby a gas mixture may be injected tangentially into chamber 56. A second chamber 58 is in axial alignment with chamber 56 and at the downstream end it is provided with a further manifold 76 and tangential injection pipes 72. The halide to be hydrolysed is introduced through a nozzle 54 from a pipe 62. If desired supplemental air may be introduced into the reaction chamber to flow around the halide injector nozzle 54 as a smooth flowing or whirling stream or such air may be injected outwardly around the periphery of the nozzle. In operation a halide is injected through pipe 62 under its own vapour pressure and the manifold 70 is supplied with a mixture of combustible hydrogen-containing gas and air which burns as a turbulent rapidly whirling flame into which the metal halides are injected and react with the water produced in the flame. At the same time a mixture of combustible gas and air is introduced into the second manifold 76, and when injected into the downstream end of the chamber 58 such mixture burns to maintain the temperature of the reactant gases above 600 DEG C. thereby diminishing absorption of acid gases produced. The product is recovered in a cyclone and ceramic filters as shown in Fig. 1 where 10 indicates a metal halide reservoir which is heated to force the halide under its own vapour pressure into the reactor 16 where it is hydrolysed to the oxide. An insulated flue 18 leads to a cyclone separator 20 and a ceramic filter 22 from which the product oxide is recovered and the gases then pass to a spray cooler 24 and a scrubber 28 to leave at 40. Suitable spraying liquids are water or a lime slurry and the spraying liquids are collected in a sump 32 from which excess liquid is withdrawn at 42 and the remainder, after the addition of the necessary neutralizing agent is re-cycled through line 36 to scrubber 28. The apparatus is suitable for the production of oxides of Al, Si, Ti, Zn, Sb, Cr, Be, Zr, Co, Ni, B, Cd, Mo and V.