FOERFARANDE FOER BLEKNING AV NS-AQ- ELLER SAP-MASSA.

摘要

The invention relates to a process for the bleaching of NS-AQ (neutral sulfite anthraquinone) pulp and SAP (semi alkaline pulping) pulp in one step by using a peroxide bleaching solution which contains, calculated from the dry weight of the pulp to be bleached: 1-5 % by weight peroxide, 0-6 % by weight sodium silicate calculated as 38 .degree.Bé waterglass, or a corresponding amount of some other stabilizing agent, and 0-1.5 % by weight sodium salt of diethylene triamine penta-acetic acid (DTPA), and/or some other complexing agent, the pH being adjusted so that the final pH of the pulp is about 8-11, preferably 9-10.