GB691911A - Method of utilising spent sulphite lye - Google Patents

Abstract

In a process for utilizing waste sulphite lyes by precipitation of the organic mass contained in the same, the waste lye obtained in the production of cellulose from wood and/or other vegetable substances by the sulphite cooking process, optionally after fermentation of the sugar contained in the waste lye, or residual liquid from the distillation column of a sulphite spirit factory, is treated at a temperature above or of 100 DEG C. with ammonia (NH3) under pressure and is subsequently acidified with mineral acids or sulphur dioxide to obtain an organic mass which can be converted economically into industrially employable products. The process may be carried out cyclically by separating the calcium sulphite from the lye after the treatment with ammonia, acidifying the remaining solution with mineral acids and collecting the sulphur dioxide evolved, filtering the organic mass, regenerating ammonia from the ammonium salts contained in the filtrate, e.g. with the aid of lime for reuse and utilizing the calcium sulphite and sulphur dioxide in the production of initial sulphite lye. If ammonium acid sulphite solution is employed in the decomposition of wood or other vegetable material the waste lyes are treated with ammonia and acidified with sulphurous acid in addition to the organic mass which is filtered off, a filtrate containing ammonium sulphite, available for use in the decomposition of wood or similar vegetable material, is obtained. The organic masses may be further treated to obtain soluble alkali lignin or condensation products which may be used in vanillin production or for combustion purposes. In examples: (1) waste sulphite lye is degasified and treated with ammonia under pressure at elevated temperature and after again degasifying and settling of the calcium sulphite the organic mass is precipitated with gaseous sulphur dioxide; (2) the residual liquid from the distillation column of a sulphite spirit factory and/or thickened spent lye is similarly treated; (3) fermented waste lye is similarly created, alcohol being distilled off with simultaneous removal of ammonia on the column.