Chlorine-free bleaching of pulp

摘要

Chemical pulp is produced by being continually fed into a bleach-line and pre-bleached with several media and at least one final bleaching stage in which it is also bleached with several media to achieve a lightness of 85-90% ISO, without using a chlorine-contg. bleach medium in any of the stages. The pump is bleached in one stage with peracid or a salt thereof and ozone, which bleaching medium is added at the same point or at different points in the bleaching line.