Patent ID: 6063291
Filing Date: 2000-05-16
Classification: C02F,C08L,Y10S

Abstract:
A process for pressure dewatering an aqueous mineral suspension having a mineral solids content of at least 150 g/l comprising mixing into the suspension water-soluble anionic bridging polymeric flocculant having intrinsic viscosity at least 5 dl/g and water-soluble cationic polymeric flocculant, wherein the anionic flocculant is in the form of a water-soluble alkali metal salt and the cationic flocculant is in the form of a water-soluble quaternary ammonium salt, allowing the suspension to flocculate and dewatering the flocculated suspension under pressure,wherein the anionic and cationic flocculants are mixed into the suspension by blending 1 part by weight of the cationic polymeric flocculant with 2 to 20 parts by weight of the anionic polymeric flocculant and sufficient water to give a polymer concentration of below 5% by weight and under conditions whereby counterionic precipitation occurs and thereby forming an aqueous composition in which substantially all the anionic polymer which is not precipitated by the cationic polymer is in solution and wherein the precipitate has formed around the dissolving cationic polymer, and mixing this aqueous composition into the suspension.