Abstract: Titanium dioxide is produced by a continuous gaseous oxidation of titanium tetrachloride or a titanium tetrachloride containing gas with oxygen or an oxygen containing gas, the improvement wherein both of said gases are separately preheated and the titanium tetrachloride or titanium tetrachloride containing gas is fed downwardly into the reactor from a burner equipped with a cooling jacket disposed at the upper part of the reactor and the oxygen or oxygen containing gas is fed downwardly through the burner into the reactor for reaction with titanium tetrachloride; and simultaneously, an inert gas and inert refractory particles are injected from the lower part of the reactor toward the inner wall of the reactor so that the inert refractory particles are caused to rise upwardly as a suspension, and the upward flow of the suspension is counter-currently contacted with the downwardly flow of the reaction product so as to rapidly cool the reaction product, and wherein the inert refractory particles injected upward

Abstract: Process for the production of a finely divided oxide of a metal or silicon by the hydrolytic conversion of a volatile corresponding metal halide or silicon halide in a flame, said process comprising feeding the volatile halide in a mixture with a combustible hydrogen-containing gas and air or oxygen to a burner provided with a mouth emitting a flame, burning the mixture in a fire tube to form a first portion of water vapor, said burner surrounded by an annular chamber forming a nozzle through which hydrogen is passed to keep the mouth of the burner free of attachments of solid substances, the quantity of oxygen or air being sufficient for the practically complete combustion of the combustible gas, and the quantities of oxygen or air and combustible gas being sufficient to produce the first portion of water vapor which will at least suffice for the hydrolysis of the volatile halides, and further wherein said flame is allowed to burn in an atmosphere consisting of gases containing a second portion of water vapo