PROCESS FOR RECOVERING POTASSIUM CARBONATE,POTASSIUM SULPHATE AND POTASSIUM LIGNOSULPHONATE FROM THE SPENT AQUEOUS COOKING LIQUOR RESULTING FROM THE PULPING OF LIGNOCELLULOSIC MATERIAL

摘要

Described herein is a process for producing potassium salts from potassium-based liquors for pulping of lignocellulosic material. The process comprises the steps of (a) digesting lignocellulosic material with a potassium-base aqueous cooling liquor to obtain an aqueous slurry of partially delignified pulp of the lignocellulosic material; (b) separating the pulp from the spent potassium-base aqueous cooling liquor; (c) concentrating the spent pulping liquor; and (d) recovering potassium salts including potassium carbonate, potassium sulphate and potassium lignosulphonate from the concentrated spent pulping liquor. The recovered potassium salts find numerous uses, an example being use in fertilizers.