A method of treating an aqueous suspension of kaolin

摘要

A method of treating a kaolin particulate material to improve its properties by removal of impurities which includes the steps of:(a) producing a dispersed aqueous suspension of a kaolin particulate material containing at least 0.1% by weight, based on the dry weight of the kaolin particulate material, of separable impurity by adding a dispersing agent to the kaolin particulate material to deflocculate solid particles of the material in the suspension;(b) conditioning the suspension prior to adding selective flocculation polymer thereto by allowing the suspension to age for a period of at least 30 minutes and optionally by adding one or more conditioning chemicals thereto;(c) adjusting the pH of the suspension to be at least about 9.5;(d) adding to the suspension at a pH of at least about 9.5 a selective flocculation polymer which facilitates separation of the separable impurity from the kaolin by flocculating the kaolin and allowing the separable impurity to be or remain deflocculated;(e) allowing the suspension at a pH of at least about 9.5 in a selective flocculation separator to separate into layers comprising a flocculated product layer and a deflocculated impurity layer containing the separable impurity; and(f) extracting the separated layers from the separator.