Process for increasing the yield in the manufacture of titanium dioxide by the chloride process

This application is a United States counterpart patent application to originating German Patent Application No. P4442783.2 filed Dec. 1, 1994, the disclosure of which is hereby incorporated by reference. An improvement to the chloride process of making titanium dioxide. By recycling some of the cyclone dust, the yield in the chlorination of titanium-containing raw materials can be increased. In order to prevent silica accumulation in the fluidized bed, the cyclone dust is divided into two fractions. An economic solution is described of a single-stage separation of the cyclone dust in a hydrocyclone, the majority of the titanium dioxide occurring in the hydrocyclone underflow, although the separation is not sharp. By grinding and drying the solids from the hydrocyclone underflow, the titanium dioxide particles returned to the lower region of the fluidized-bed reactor are rapidly chlorinated, while the quartz and coke particles are rapidly discharged again from the fluid bed, so that no silica contamination occurs.