| 摘要 |
<p>The invention relates to a process for bleaching chemical pulp, comprising a alkaline oxygen delignification step and a subsequent hydrogen peroxide bleaching step and involving removal of undesirable metal ions before and/or during the peroxide bleaching step by means of a chelating agent, wherein a polyamino disuccinic acid derivative, preferably ethylenediamine disuccinate (EDDS), is used as chelating agent at a pH value above 9.5, preferably at a pH value ranging from 10 to 11. The invention also relates to intermediate pulp dispersions containing a polyamino disuccinic acid derivative, preferably ethylenediamine disuccinate (EDDS), in a concentration of 0.01 to 2.5 % w/w on dry pulp substance and at a pH value above 9.5.</p> |
