Abstract: A method for increasing the bulk density and decreasing the time of wetting with water of a substantially anhydrous kaolin clay powder, comprising dry milling said powder in a media mill wherein the media is at least +5 mesh, and using work inputs of from about 5 to about 40 HP-hrs/ton of dry clay. The process enables improved handling characteristics for the treated clay with respect to bulk material handling systems.

Abstract: A method is disclosed for processing a natural calcitic ore to yield a finely divided calcium carbonate particulate of very high brightness characteristics. The natural calcitic ore is initially coarse-milled to produce a product wherein no more than 5% by weight of the particulate is +325 mesh, and no more than 35% by weight of the particles are of less than 2 microns E.S.D. This coarse-milled product is then subjected as an aqueous slurry containing less than 40% and preferably less than 30% solids by weight, to a froth flotation, which separates with the froth the relatively coarse colorbodies liberated in the initial grinding. Preferable compositions for use in the froth flotation comprise 1-substituted-2-alkyl imidazolines or the salt derivatives thereof, with such compounds being utilized in admixture with a substantially non-polar aliphatic compound having from 10 to 20 carbon atoms in its longest straight chain.

Abstract: A method is disclosed for processing a natural calcitic ore to yield a finely divided calcium carbonate particulate of very high brightness characteristics. The natural calcitic ore is initially coarse-milled to produce a product wherein no more than 5% by weight of the particulate is +325 mesh, and no more than 35% by weight of the particles are of less than 2 microns E.S.D. This coarse-milled product is then subjected as an aqueous slurry including less than 40% solids, to a froth flotation, which separates with the froth the relatively coarse colorbodies liberated in the initial grinding. The purified underflow is then dewatered to at least 60% solids by weight, and is wet-milled, as for example in a sand mill, to yield an output product wherein at least 80% by weight of the resultant particulate has an E.S.D. of less than 2 microns, the product being further characterized by a brightness of at least 94 on the G.E. scale.