Processes of reducing contamination from cellulosic suspensions

Abstract

A method of removing synthetic hydrophobic resinous particles from a waste treatment process in which an aqueous cellulosic suspension is formed from waste cellulosic material in a pulping stage, passing the cellulosic suspension to a separation stage in which particles of ink and/or synthetic hydrophobic resinuous materials are separated from the cellulosic suspension, and optionally subjecting the cellulosic suspension to a washing stage and/or thickening stage to provide a treated pulp, in which process water from the separation stage and/or washing and/or thickening stages is clarified in a clarification stage in which suspended solids, comprising synthetic hydrophobic resinous particles are removed, and the clarified water is fed to the pulping stage in a clarification loop and/or combined with the treated pulp, wherein a water soluble cationic polymer is added to the process water at or prior to the clarification stage, characterised in that the water soluble cationic polymer formed from a monomer blend comprising, a first water soluble cationic monoment selected from the group consisting of diallyl dialkyl ammonium halide, dialkylaminoalkyl (meth)acrylamide and dialkylaminoalkyl (meth)acrylate, including quaternary ammonium salts and acid addition salts thereof, and a second water soluble cationic monomer comprising a hydrophobic moiety.

Dependencies are inferred from the claim text.