GB866002A - Process for treating the residual gases in the manufacture of titanium tetrachloride - Google Patents

Abstract

Hydrochloric acid of at least 20% by weight strength is recovered from the residual gaseous mixture resulting from the manufacture of titanium tetrachloride by chlorinating a titanium bearing material in the presence of the reducing agent and p separating the solid chloride product. Such a residual gaseous mixture, consisting mainly of carbon monoxide and dioxide, hydrogen chloride and small amounts of silicon and titanium tetrachloride is contacted with an organic liquid in which hydrogen chloride is insoluble or sparingly soluble and in which the said tetrachlorides are soluble and the resulting gaseous mixture is thereafter treated with a limited quantity of water to produce the hydrochloric acid solution. Clogging of the washing towers by hydrolysis of silicon and titanium tetrachloride contaminates is thereby avoided. The organic liquid is preferably a liquid paraffin hydrocarbon, such as n-heptane, or halogenated hydrocarbon, such as carbon tetrachloride, chloroform, trichlorethylene, chlorinated diphenyls, and in particular o-dichlorobenzene. The absorption of the tetrachloride is preferably effected at atmospheric pressures at temperatures from -40 to 70 DEG C. and the gas and absorbent liquid preferably flow in countercurrent down a packed tower. Silicon and titanium tetrachloride adsorbed may be recovered by distillation or alternatively they may be subjected to hydrolysis and converted to insoluble products which are filtered off.