Patent attributes
There is provided a method of producing a kaolin particulate material suitable for use as an improved super-calendered filler. This method includes: (a) preparing an aqueous feed suspension of kaolin; (b) treating the kaolin of the feed suspension by attrition grinding in a vessel using grinding media granules; (c) delivering an aqueous suspension of the kaolin ground in (b) to a particle size classifier and separating the kaolin of the suspension into a coarse fraction and a fine fraction; (d) returning an aqueous suspension of the coarse fraction produced in (c) to the grinding vessel to be further attrition ground; and (e) extracting an aqueous suspension of the fine fraction produced in (c) as a product suspension. Advantageously, the kaolin of the feed suspension in (a) is such that not more than 30% by weight has a particle size less than 2 μm and not more than 30% by weight has a particle size greater than 10 μm. In addition, the kaolin of the product suspension produced in (e) is such that not more than 10% by weight has a particle size greater than 10 μm and not more than 10% by weight has a particle size less than 0.25 μm.
