Abstract: The present invention relates to methods of precipitating calcium carbonate (PCC) in a manner that can control the size and surface area of PCC. For example, the calcium carbonate crystals can be formed through the use of two or more doses of slaked lime slurry in the presence of a substrate. Alternatively, the PCC can be formed by combining one or more slaked lime slurry doses with preformed PCC. The invention also relates to a method of precipitating substantially discrete calcium carbonate and to a system for precipitating calcium carbonate.

Abstract: The present invention relates to a composition comprising an alkaline earth metal carbonate and a substrate, where the composition has a reduced amount of grit, such as an amount less than or equal to about 0.5% by weight relative to the total weight of the composition. The composition can be a filler composition for use in, for example, paper making applications. Where the alkaline earth metal is a calcium carbonate, the grit can be reduced by degritting a slaked lime slurry prior to precipitation of the alkaline earth metal with the substrate. The degritting can be performed by hydrocycloning the lime slurry. The invention also relates to a method of coprecipitating calcium carbonate onto a substrate, and to a method of reducing grit in such compositions. The invention also relates to uses of these compositions, such as in paper-making applications, and to systems for producing these compositions.

Abstract: The invention provides a method of grinding an inorganic particulate material such as calcium carbonate or kaolin in an aqueous suspension, preferably at a solids level below about 50% by weight, wherein the aqueous suspension includes a sub-effective amount of a dispersing agent for the inorganic particulate material.