METHOD FOR DEWATERING SLUDGE OF CELLULOSE, PAPER OR CARDBOARD MANUFACTURING PROCESS Russian patent published in 2021 - IPC C02F1/56 C02F11/14 

FIELD: paper industry.

SUBSTANCE: invention relates to a method for dewatering sludge of cellulose, paper or cardboard manufacturing process, such as sludge of removing printing inks. A method for dewatering sludge of cellulose, paper or cardboard manufacturing process, including sludge of removing printing inks, includes obtaining aqueous sludge containing an aqueous phase and fibrous material suspended in the aqueous phase, processing sludge at a pre-thickening stage, in which the first part of the aqueous phase is removed from sludge, processing sludge at a pressing stage, in which the second part of the aqueous phase is additionally removed from sludge and dry pressed sludge is obtained, at the same time, a polymer composition having charge density of at most 1.7 meq/g at pH 7.0 and containing the first cationic synthetic polymer with charge density of at least 1.0 meq/g at pH 2.8, the second cationic polymer, which is copolymer obtained by polymerization (meth)acrylamide and at least one second cationic monomer, is added to aqueous sludge before or during the pre-thickening stage, while the amount of cationic monomer is 1-10 mol.% relatively to the total number of monomers, while the second polymer is polymerized in the presence of the first cationic polymer, while the first polymer has higher charge density than the second polymer.

EFFECT: technical result is obtaining a method for dewatering sludge of cellulose, paper or cardboard manufacturing process.

17 cl, 11 tbl