COLORED TITANIFEROUS PIGMENT OBTAINED BY PURIFYING KAOLIN

摘要

Described is a process for separating a mixture of finely divided minerals into constituents thereof. In particular, the invention relates to a procedure for effecting such separation by a novel selective flocculation technique wherein a dispersed aqueous pulp containing the mixture of minerals is preconditioned for selective flocculation with an anionic polymer by addition of both a fatty acid such as oleic acid and source of polyvalent cation such as calcium chloride. The fatty acid and cation of the salt selectively coat the component of the mixture that is subsequently flocculated with the anionic polymer. A polyacrylate salt dispersant is preferably used in the process. The invention is especially adapted to the separation of colored titaniferous impurities from kaolin clay in which case both a white purified kaolin product and a strongly flocculated dun-colored titania/kaolin mixture are recovered and then dispersed producing a material useful as a paper coating pigment.