Production of surface-treated calcium carbonate fillers involves precipitation coating with an aluminate optionally after mixing the carbonate with a di- or poly-carboxylic acid

摘要

Production of a calcium carbonate filler involves acidifying a mixture of an aqueous CaCO3 particle suspension and an aqueous solution of an aluminate surface treating agent to give a pH at which the dissolved aluminate precipitates; and separating the particles from the liquid and drying and milling them. Independent claims are also included for the process as above but in which the aqueous CaCO3 particle suspension is mixed with a solution of a di- or poly- carboxylic acid surface treating agent before being mixed with the aluminate solution; and the process again as above but in which CaCO3 particles and a di- or poly-carboxylic acid surface treating agent are mixed and homogenized before being suspended in water and then mixed with the aluminate solution.