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US 7,070,696 B2Granted
Process for flocculating suspensions
AssigneeCiba Specialty Chemicals Water Treatments Ltd.
InventorsSteven Weir, Michael Green, John Stephen Robinson, Tony Whittaker, Malcolm Skinner
Life of this patent
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Abstract
A process of flocculating and dewatering an aqueous suspension of suspended solids comprising, introducing into the suspension, (a) substantially linear polymer, (b) structured polymer, characterised in that the polymers are introduced into the substrate sequentially. The process brings about improvements in filtration.
Claims6
A process of flocculating and dewatering an aqueous suspension of suspended solids comprising, introducing into the suspension,
- (a) substantially linear cationic polymer,
- (b) structured polymer,
- in which polymer (b) has ionic regain greater than 20% and is cationic wherein said ionic regain is calculated as (x−y)/x multiplied by 100 where x is the ionicity of the polymer (b) measured after applying standard shear and y is the ionicity of the polymer (b) before applying standard shear characterised in that the polymers are introduced into the substrate sequentially and polymer (a) is added first then polymer (b) to flocculate said suspended solids, and dewatering said aqueous suspension, wherein polymers (a) and (b) are copolymers of acrylamide and at least one cationic monomer selected from the group consisting of quaternary ammonium and acid salts of dimethyaminoethyl (meth) acrylate, quatemary ammonium and acid salts of dimethylaminoethyl (meth) acrylamide, and diallyldimethyl ammonium chloride.
Dependencies are inferred from the claim text.