PROCESS FOR RECOVERING CHEMICALS FROM THE WASTE LIQUORS OF SULFATE CELLULOSE DIGESTION AND THE WASTE WATERS OF BLEACHING

摘要

PROCESS FOR RECOVERING CHEMICALS FROM THEWASTE LIQUORS OF SULFATE CELLULOSE DIGESTIONAND THE WASTE WATERS OF BLEACHINGABSTRACT OF THE DISCLOSUREA process for the recovery of chemicals from thewaste liquors of sulfate cellulose digestion and from thewaste waters of bleaching, wherein a melt from a soda-ashroaster, mainly containing sodium sulfide and sodium carbonate,but also sodium chloride, is dissolved and clarified toproduce green liquor containing sodium carbonate, sodiumsulfide and sodium chloride is disclosed. The sodiumcarbonate and the sodium sulfide, which contains most of thesodium chloride, are separated from each other, at least partof the sodium chloride being separated by evaporation crystal-lization from the sodium sulfide in solution, at least partof the sodium carbonate being causticized into sodiumhydroxide, and the sodium hydroxide and sodium sulfide insolutions being mixed together in a ratio suitable to form adigestion solution with a desired sulfide content.