GB1330157A - Production of titanium dioxide - Google Patents

Abstract

1330157 Vapour phase coated TiO 2 BRITISH TITAN Ltd 29 Nov 1971 [23 Dec 1970] 61293/70 Heading C1N TiO 2 particles are coated in suspension in a gas stream with a first coating of an anhydrous oxide of Al, Zr or Si, and then with a second coating of a hydrated oxide of Al, Zr or Si by mixing a halide with the gas stream which is at a temperature below 600‹ C. and then adding steam when the temperature is below 350‹ C. The TiO 2 may be obtained directly from a vapour phase TiCl 4 oxidation and may contain Al and Si oxides. The first coating may be produced by adding halide and O 2 to the gas stream when the temperature is at least 450‹ C. The gas stream may then be cooled by coolant fluid in a jacket or by adding cold gas, e.g. recycle gas, or by adding steam, which also reacts with residual halide. The second halide, preferably a chloride, may be introduced through a single inlet or a plurality of inlets spaced apart along the direction of flow. The steam may be superheated, and may be obtained by burning propane in O 2 . The product may be further treated with steam and butylamine. In a comparative example, the once-coated TiO 2 is given a second wet coating.