USE OF XYLANASE IN PULP BLEACHING

摘要

The present invention discloses methods of bleaching chemical pulp with xylanase after chemical bleaching. The method comprises the steps of treating chemical pulp with a first xylanase in a first enzyme treatment stage to produce an enzyme treated pulp, exposing the enzyme treated pulp to a chemical bleaching stage to produce a partially bleached pulp, and treating the partially bleached pulp with a second xylanase in a second enzyme treatment stage at a pH of about 3 to about 8. Further, there is disclosed a method of bleaching pulp comprising the steps of exposing chemical pulp to a chlorine dioxide bleaching stage to produce a partially bleached pulp, treating the partially bleached pulp with a xylanase in an enzyme treatment stage at a pH of about 3 to about 8, then carrying out an alkaline extraction of the pulp. The pulp bleaching method of the present invention may be performed in a pulp mill as part of a complex pulp bleaching process.