Use of filters from oxygen treatment steps in the production of coke ovens

摘要

Acidic bleach plant effluents from a cellulose pulp mill utilizing a sodium-based cooking process are effectively utilized without contamination of pulp mill processes with undesirable metal ions. The bleach plant effluent, in the form of filtrate, is treated with an alkaline stream to precipitate solids containingmetals from the filtrate, producing a reduced metal content filtrate. The reduced metal content filtrate is used to wash or dilute lime mud which is in turn used to produce lime for causticizing green liquor to produce white liquor.Acid filtrate which is not treated to remove metals may be used to dissolve smelt from the recovery boiler to make green liquor which is clarified to produce clarified green liquor and dregs containing metals. The alkaline stream used to precipitate solids from the acidic filtrate is preferably clarified green liquor or white liquor, although an alkaline filtrate from an alkaline bleaching or delignification stage may be used.