Slurries of kaolin clay are often pumped over long distances from the mining site to secondary operations. Deflocculants enable the formation of slurries of reduced viscosities, relatively higher solids content and increased stability. They also provide an improvement in the separation of clay from impurities of large size. The use of deflocculants prior to spray-drying reduces the amount of water that must be evaporated and prevents deposition and plugging in the dryer. Condensed polyphosphates are effective deflocculants for kaolin and are used extensively in the initial deflocculation step.