METHOD FOR REMOVING LIGNIN-CARBOHYDRATE COMPLEX FROM BLACK LIQUOR IN SULFATE CELLULOSE PRODUCTION (3 VARIANTS) Russian patent published in 2021 - IPC D21C11/00 C08H7/00 

FIELD: cellulose industry.

SUBSTANCE: group of inventions relates to the field of cellulose production and can be used for the removal of a lignin-carbohydrate complex from black liquor in the production of sulfate cellulose. The proposed methods for removing the lignin-carbohydrate complex from the black liquor in the production of sulfate cellulose include processing the liquor with a temperature of up to 95°C and a concentration of 7-40% on dry matter with a liquid saturated with carbon dioxide at a pressure of 3.0-7.0 atm, separation of lignin from the liquid phase with flotation foam, and the black liquor is treated with a liquid saturated with carbon dioxide at temperatures of 20-40°C to a pH of 7-8 and containing additionally as a precipitator highly dispersed particles of the solid phase of mineral origin, natural or re-precipitated calcium carbonate, or particles of organic origin, wood flour, while decanting the liquid phase from the solid, filtering the formed flakes of the lignin-carbohydrate complex to obtain the finished product.

EFFECT: simplifying the technology of separating the lignin-carbohydrate complex from black liquor by reducing the time of treatment with carbon dioxide, eliminating flotation while improving filtration due to a controlled phase separation process, with the production of well-filtered sediment.

3 cl, 3 ex