Abstract: A method for milling a powder in a high energy mill which includes steps of forming a milling slurry including a naturally occurring zirconium silicate sand grinding medium having a density in the range of from about 4 g/cc absolute to about 6 g/cc absolute. Also provided is a grinding medium including naturally occurring zirconium silicate sand characterized by a density in the range of from about 4 g/cc absolute to about 6 g/cc absolute.

Abstract: The present invention provides a pigmentary titanium composite having good durability and excellent optical properties. The inventive composite consists essentially of: a particulate titanium dioxide base; a hydrous zirconium oxide layer deposited on the titanium dioxide base; and a hydrous alumina layer deposited on the hydrous zirconium oxide layer. The alumina layer consists essentially of boehmite alumina and/or pseudoboehmite alumina.The present invention also provides a method for preparing the inventive pigmentary composite. The inventive method comprises the steps of: (a) preparing an aqueous slurry comprising water and a particulate titanium dioxide base; (b) depositing a layer of a hydrous zirconium oxide precipitate on the titanium dioxide base; and (c) depositing a layer of a hydrous alumina precipitate on the layer of hydrous zirconium oxide. The hydrous alumina precipitate consists essentially of boehmite alumina and/or pseudoboehmite alumina.

Abstract: The invention relates to a method for the preparation of particulate pigmentary titanium dioxide. The method comprises reacting, in solution, a precursor titanium tetrahalide with sulfuric acid to produce an intermediate titanyl sulfate product. Following crystallization and recovery of this intermediate product from solution the crystallized intermediate is redissolved in an aqueous solvent medium and hydrolyzed at elevated temperatures to provide a particulate amorphous titanium dioxide intermediate product. After separation from the aqueous solvent medium, this intermediate product then is subjected to calcination at elevated temperatures to produce the desired particulate titanium dioxide end product.

Abstract: Chemically inert pigmentary zinc oxide compositions, useful in producing UV light stable polymeric resin compositions are prepared by wet treatment of chemically reactive zinc oxide base pigments utilizing a process wherein chemically inert organic or inorganic coatings are deposited thereon.