When the process of my invention is used in a re?nery
employing the carbonation process, carbonation can be
carried out in a conventional manner, with a lime addition in the range of about 0.2% to about 2.0% by weight of CaO on the basis of liquor solids.
The impurity precipitate produced by the addition of the cationic surfactant is
filtered off simultaneously with the normal calcium carbonate precipitate. An incidental but important advantagearising from the use of the invention is that, if the cationic
surfactant is dosed into the carbonation tank, the subsequent ?ltrability of the precipitate is improved by up to 100% over the ?ltrability of the conventional calcium
carbonate precipitate formed when no surfactant is used.