Process for treating spent, waste, alkaline digestion liquor from paper pulping operations and product
AssigneeBountiful Applied Research Corporation
InventorHassan El Shall
Life of this patent
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Abstract
A water soluble, surface active, polymeric agent is mixed with digestion liquor, preferably with an additional surface active defoamer coagulant agent prior to or during acidification of the alkaline digestive liquor. This results in an easily separable, non-gelatinous, non-gummy, coagulated lignin as a solids, particulate fraction that tends to float on a clarified liquid fraction containing recoverable salts. The solids fraction and the liquid frictions are easily separated, one from the other, by a gravity separation step.
Claims14
A process for treating a substantially spent, alkaline and non-sulphite digestion liquor obtained from a pulping plant of the paper making industry, said digestion liquor containing lignins as potential precipitants upon acidification of said digestion liquor, leaving substantially clarified residual liquid, said process comprising the steps of:
- mixing into said spent digestion liquor a water soluble, surface active, polymeric, coagulant agent;
- acidifying the so mixed liquor to a pH below 7 to precipitate the lignins and other organic compounds and to coagulate them as solids which tend to float to the surface of the residual liquid;
- and
- separating the coagulated solids and the residual liquid, one from the other.
A process for treating a spent kraft alkaline digestion liquor containing lignins and liquid, comprising the steps of:
- (a) mixing into said spent kraft digestion liquor a water soluble, surface active, polymeric coagulant agent;
- (b) acidifying the spent digestion liquor of step (a) to a pH below about 3 to cause lignins and other dissolved organic compounds of the spent digestion liquor to coagulate as solids and float to the surface of the spent digestion liquor;
- and
- (c) separating the coagulated solids and the residual liquid of the acidified spent digestion liquor, one from the other.
Dependencies are inferred from the claim text.