Originally, hydrogen peroxide was mainly used for mechanical bleaching. Nowadays, there is rapid growth in chemical bleaching and bleaching of deinked pulp.
In the bleaching of mechanical pulp, alkaline hydrogen peroxide can obtain high whiteness and high stability, and can not increase the strength under the condition of high yield. Medium concentration single stage bleaching has developed to high concentration single stage and two stage bleaching. The bleaching process has a complete control system, there are online optical test head and residual chemical test head. Today, the bleaching degree of coniferous CTMP pulp can reach 80 degrees Celsius ISO, and the folding degree of hardwood pulp can reach 85 degrees Celsius ISO.
Bleaching of chemical pulp is a controversial issue. Due to the trace amount of dioxins in the waste solution of bleaching, bleaching towards chlorine was initiated ten years ago in order to eliminate the production of organic chlorides.
In the advancement of process technology, hydrogen peroxide has become the main bleaching agent in chlorine free bleaching (ECF, chlorine dioxide-based bleaching process) and total chlorine free bleaching (TCF). The rapid development of hydrogen peroxide as a true bleach for high whiteness is taking environmental considerations into account. Three years ago, pressurized oxygen bleaching at 100 degrees Celsius was perfected in many factories. The bleaching efficiency of hydrogen peroxide is enhanced and the bleaching cost can be saved.
