METHOD FOR UTILIZING LIGNIN SEPARATED FROM BLACK LIQUID AS LIME-KILN FUEL Russian patent published in 2019 - IPC D21C11/00 

FIELD: textile and paper.

SUBSTANCE: object of the present invention is a new method of utilizing lignin-containing material separated from spent kraft pulping liquor (black liquor) by (a) acidifying the liquor, or fraction thereof, to a pH not less than 7 thereby precipitating solid particles, (b) separating precipitated solid particles from the accompanying liquid and (c) subjecting material thus separated to a washing process exhibiting the following essential features: (I) separated material is washed with an aqueous medium or aqueous media in one or more steps, (II) in each washing step, the washing medium contains, in a dissolved form, significant amounts of one or more added sodium salts, and (III) the combined concentration of the added sodium salts in the washing medium in each washing step exceeds 3 % by weight, preferably exceeds 5 % by weight and most preferably exceeds 10 % by weight.

EFFECT: despite the relatively large amount of sodium remaining in the washed lignin-containing material, this material, after possible partial or complete drying, is used as a fuel in a lime kiln of a pulp mill.

9 cl, 2 dwg