METHOD FOR HANDLING SPENT WASH SOLUTION OF LIGNIN-RECOVERY PROCESS Russian patent published in 2018 - IPC D21C11/00 

FIELD: paper production; cellulose production.

SUBSTANCE: at least part of a spent wash solution is introduced into a chemical recovery cycle at a location in that part of the cycle which starts at, and includes, the smelt dissolving stage and ends at, and includes, the pulping stage. In preferred embodiments, input of other water and/or aqueous solution into the chemical recovery cycle after the recovery boiler is adjusted so that, as a consequence of the introduction of the spent wash solution, the amount of water in the white liquor going to the pulping line is not significantly increased. Among others, two preferred locations for the introduction of the spent wash solution are (1) the smelt dissolver and (2) the location where unwashed lime mud is diluted.

EFFECT: object of the present invention is a new method for treating spent wash solution resulting from washing a lignin, which is precipitated and then separated from spent alkaline pulping liquor.

6 cl, 3 dwg