GB535214A - Preparation of titanium dioxide - Google Patents

Abstract

535,214. Titanium dioxide. CLEVELAND, F. J. (Pittsburgh Plate Glass Co.). Aug. 29, 1939, No. 24806. [Classes 1 (iii) and 95] In the production of titanium di-oxide by thermal decomposition of a vaporized titanium halide, especially TiCl 4 , in the presence of an oxidizing gas and in order to prevent the formation of large crystals, the reaction mixture is maintained substantially out of contact with hot surfaces during the decomposition, this being effected by the provision of an inert or non-oxidizing atmosphere such as nitrogen or carbon di-oxide. The inert atmosphere may be provided, as in the apparatus shown, by means of a stream of the inert gas issuing from a tube 7 surrounding the inlet 5 for TiCl 4 , oxidizing gas being introduced at 9 and evolved chlorine withdrawn at 10. In an alternative method drops of liquid titanium tetrachloride may fall through an inert atmosphere into the oxidizing zone. A mixed pigment may be produced by addition to the gas stream of zinc vapour, aluminium chloride, iron chloride, antimony, tin lead and bismuth compounds, silicon tetrachloride which are oxidized to the respective oxides. Barium sulphate and sulphide may also be added to the titanium oxide. Specifications 258,313 [Class 1 (iii)], and 535,213 are referred to.