US Patent 7749392 Dewatering process

A process of dewatering an aqueous suspension employing a flocculating system comprising treating the suspension with a flocculating amount of a first flocculant and a dewatering amount of a second flocculant, and subjecting the suspension to mechanical dewatering to form a cake, wherein the first flocculant brings about flocculation and assists thickening of the suspension and the second flocculant further dewaters the suspension, characterized in that the second flocculant is a water-soluble or water swellable polymer that is mixed into the suspension in the form of aqueous composition comprising dissolved or hydrated polymer having a Brookfield viscosity of above 30,000 cps (measured at 20° C.).