Improving peroxide bleaching of mechanical pulps by the P_(M) process

摘要

Typically, peroxide bleaching of mechanical pulps is performed by first preparing the bleach liquor in the so-called cascade system and then adding the bleach liquor to the pulp slurry via a mixer/pump. We found that a significant improvement in the bleaching performance can be achieved by modifying the process so that silicate and sodium hydroxide are added to the pulp first, followed by the addition of hydrogen peroxide. Both the laboratory results and mill trials will be reported. The underlying mechanism to account for the improvement will be discussed.