PAPER PULP BLEACHING METHOD Russian patent published in 2021 - IPC D21C9/14 D21C9/16 

FIELD: paper-making.

SUBSTANCE: present invention relates to a method of bleaching unbleached or pre-bleached paper pulp, which includes at least the following sequential stages: a) obtaining unbleached or pre-bleached paper pulp with a pH value of at least 8, b) bringing the paper pulp obtained at the end of the stage a) into a contact with chlorine dioxide, c) adding at least one Bronsted base into the paper pulp if pH of the paper pulp obtained at the stage b) is less than 10, d) adding hydrogen peroxide into the paper pulp obtained at the end of the stage c), e) keeping the paper pulp obtained at the end of the stage d) in the first bleaching tower, f) not necessarily adding sulfuric acid into the paper pulp obtained at the end of the stage e) and keeping the obtained paper pulp in the second bleaching tower. The method does not require the stage of flushing the paper pulp before the end of the stage e) and, if applicable, before the end of the stage f).

EFFECT: obtaining a paper pulp bleaching method.

13 cl, 5 tbl, 2 ex, 6 dwg