Process for treating spent, waste, alkaline digestion liquor from paper pulping operations and product

摘要

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.