Low chemical consumption closed mill

Abstract From the Canadian patent

A closed mill concept that significantly reduces the chlorine consumption and thereby makes the closed mill concept practical. Digested cellulosic pulp is oxygen bleached at an oxygen bleaching stage, and then washed in a brown stock washer. The washed, oxygen bleached pulp is then chlorine bleached, and the effluent from the chlorine bleaching stage is returned to the washing stage as washing media. The chlorination preferably is effected at a solids consistency of about 6% to 12%. By practicing the invention the total organic carbon entering the chlorination stage may be reduced to about 43% as much as in conventional closed mill concepts, and the recycled organic loading is reduced so …