METHOD OF BLEACHING KRAFT PULP

摘要

The present invention relates to a method of bleaching sulfate cellulose pul p to a brightness of at least ISO 85 by using at least two of the following bleaching chemicals: oxygen, ozone, and peroxide. Characteristic features of the invention are that the pulp is digested; subjected to a heavy metals removal treatment with at least one of the following treatment agents or methods: acidification, EDTA, and DTPA; delignified in a pressurized two-ste p oxygen stage; and bleached at least in one acid peroxide stage.