Patent ID: 6346167
Filing Date: 2002-02-12
Classification: D21C,D21G

Abstract:
A method of producing kraft pulp by cooking comminuted cellulosic fibrous material comprising the steps of, at at least one stage during kraft cooking of the material to produce pulp and liquor surrounding the pulp which contains dissolved organic material:(a) extracting from the cellulosic material liquor containing a level of dissolved organic material substantial enough to adversely affect at least one of pulp strength, H factor, amount of effective alkali, and bleachability of the pulp; and (b) replacing in the cellulosic material some or all of the extracted liquor with liquor containing a substantially lower effective dissolved organic material level than the extracted liquor, so as to positively affect at least one of pulp strength, H factor, amount of effective alkali, and bleachability of the pulp, wherein steps (a) and (b) are practiced to keep the effective dissolved organic material concentration at 100 g/l or less throughout substantially the entire kraft cook.