METHOD FOR BLEACHING MECHANICAL AND CHEMITHERMOMECHANICAL PULP

摘要

The present invention relates to a method for bleaching mechanical and chemithermomechanical pulp including that an advancing pulp suspension obtained after that the fibres are laid free is prebleached by adding reductive bleaching agent to the pulp suspension in a location just after th e fibres are laid free and that the bleaching is carried out under given conditions in the form of high temperature and minimized oxygen access in respect of said adding location and immediately downstream of said location, characterized in, that the in the described manner prebleached pulp is subjected to at least one further bleaching treatment including that the pul p is bleached with an oxidizing bleaching agent, preferably peroxide bleaching agent, reinforced with borohydride.