Tronox patents zirconia-

April 15, 2008

Patent No. U.S. 7,238,231 B1
Tronox LLC has obtained a patent for a process for manufacturing zirconia-treated titanium dioxide, comprised of the steps of (a) forming a mixture comprised of a titanium dioxide material in water; (b) wet milling the mixture; (c) after step b, optionally depositing on the wet milled titanium dioxide material one or more inorganic oxides selected from the group consisting of the oxides of aluminum, boron, cerium, phosphorus, silicon, tin, titanium and zirconium; (d) achieving a pH of the mixture resulting from steps b or c between 5 and 9, whereby the titanium dioxide material is sufficiently flocculated to be recovered by vacuum or pressure filtration; (e) removing the titanium dioxide material from the mixture by vacuum or pressure filtration; (f) washing the titanium dioxide material recovered by filtration; (g) converting the washed titanium dioxide material to a fluid dispersion by addition of one or more alkaline water-soluble zirconium reagents selected from the group consisting of ammonium zirconyl carbonate, the water-soluble ammonium zirconyl carboxylates and mixtures of these; and (h) drying the dispersion to yield a dry zirconia surface treated titanium dioxide powder.