| 摘要 |
A method for bleaching lignocellulose-containing fiber material in the form of chemical pulp without using chloric bleaching agents where the pulp is treated with chelating agent and is bleached with ozone and peroxide. Immediately after the ozone bleaching the pulp is treated with chelating agent in a second chelating step at a pulp concentration of 1-10 % for 1-30 minutes at the temperature of 20-90 DEG C and the pH value 1,5-5. The pulp thus treated is washed and dewatered to a concentration of 8-40 % prior to the peroxide bleaching. |
