Anglo-american Clays Corporation

Anthony D McConnell

William M Price

Herbert I Lewis

Robert H Garner

An anhydrous white kaolin clay pigment is disclosed, which consists of porous aggregates of kaolin clay platelets. The pigment exhibits exceptionally high light-scattering ability when incorporated as a filler in paper. The aggregates have an average specific gravity in the range of 0.5 to 0.6, and a size distribution such that not more than 5% by weight thereof are of greater than 10 microns ESD, at least 75% are of less than 2 microns ESD, and not more than 15% are of less than 1 micron ESD. The pigment has a Valley abrasion value below 30 mg, and preferably below 20 mg, and a GE brightness of at least 93. The mean size of the internal pores in the aggregates is less than 0.55 microns and preferably is less than 0.5 microns. This low mean pore size is deemed instrumental in producing the aforementioned high scattering ability. A method for producing the said pigment is also disclosed and claimed.

Anhydrous kaolin clay pigment and method of preparation

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. The purified underflow from the flotation step is 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 95 on the G.E. scale.

Method for brightening natural calcitic ores

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.

Growing community of inventors

Sandersville, GA, United States of America

Anthony D McConnell