| 摘要 |
The present invention relates to a method for end-bleaching of pulp containing metal ions after a sequence comprising alkaline bleaching stages only and optionally treatment with complex forming agent, wherein the end-bleaching comprises two chlorine dioxide stages at a pulp concentration of 8-20% and pH 2.5-4.5 wherein the pulp after the first chlorine dioxide stage is washed and dewatered to a concentration of 12-50% for removal of the out-dissolved metal ions and that alkali thereupon is added to the pulp for fast alkali extraction and increase of pH to 8-14, whereupon the pulp is provided with acid and chlorine dioxide and introduced into the second chlorine dioxide stage. |
