Grinding alkaline earth metal pigments

摘要

There is disclosed a process for producing a finely ground alkaline earth metal pigment. The process comprises the steps of: (a) preparing an aqueous suspension comprising from 40 to 70% by weight of a particulate alkaline earth metal compound, such as calcium carbonate; (b) subjecting the suspension formed in step (a) to attrition grinding with a particulate grinding medium under conditions such as to yield a product having a particle size distribution such that at least 90% by weight of the particles have an equivalent spherical diameter smaller than 2 mu m, and preferably at least 80% by weight of the particles have an equivalent spherical diameter smaller than 1 mu m; and (c) allowing water to evaporate from the suspension under the action of heat contained in the suspension until the percentage by weight of dry alkaline earth metal compound in the suspension is at least 70% by weight.