An improved process is described for manufacturing zirconia-treated
titanium dioxide pigments, wherein the zirconia treatment is accomplished
in the process of fluidizing a titanium dioxide filter or press cake and
then drying the same, through the addition to the filter or press cake of
one or more alkaline water-soluble zirconium reagents selected from
ammonium zirconyl carbonate, the water-soluble ammonium zirconyl
carboxylates and mixtures of these. Aqueous solutions of such zirconium
reagents, in addition to being effective for imparting a zirconia surface
treatment to the titanium dioxide materials, also prove to be effective
fluidizing agents for forming high solids dispersions of the
zirconia-treated titanium dioxide pigment materials which can be spray
dried without substantial dilution and excessive energy requirements.