PROCESS FOR INCREASING THE YIELD IN THE MANUFACTURE OF TITANIUM DIXOIDE BY THE CHLORIDE PROCESS

An improvement to the chloride process of making titanium dioxide. By recycl ing some of the cyclone dust, the yield in the chlorination of titanium-containing ra w 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 sepa ration of the cyclone dust in a hydrocyclone, the majority of the titanium dioxide occurring in th e hydrocyclone underflow, although the separation is not sharp. By grinding the dried solid s 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 par ticles are rapidly discharged again from the fluid bed, so that no silica contamination occurs.