METHOD FOR CELLULOSE CHEMICAL BLEACHING Russian patent published in 2011 - IPC D21C9/14 

FIELD: chemistry.

SUBSTANCE: method, in which initial cellulose bleaching includes first treatment with chlorine dioxide (D0), also involves adding an alkali to the cellulose after adding chlorine dioxide and subsequent alkaline treatment with oxygen and hydrogen peroxide (EOP), wherein these steps are separated by a washing step. The method also involves treating cellulose to lower content of transition metals in the cellulose before the said peroxide treatment in accordance with which initial bleaching comprises the DON EOF sequence. The pH of the cellulose is set to a value between 8 and 11 before the washing step with the said addition of alkali. Thus, organic substances in the cellulose dissolve and are removed from the cellulose during the said washing step as a filtrate which also contains a large portion of formed chlorides, wherein entrance of this filtrate into the recycling system is not allowed, and content of chlorides in the filtrate from the washing step after the said EOP step drops.

EFFECT: low consumption of bleaching chemicals and high efficiency of the alkaline step.

12 cl, 10 dwg