| 摘要 |
PCT No. PCT/SE93/00988 Sec. 371 Date Jun. 7, 1994 Sec. 102(e) Date Jun. 7, 1994 PCT Filed Nov. 18, 1993 PCT Pub. No. W094/29511 PCT Pub. Date Dec. 22, 1994A process for chlorine-free bleaching of chemical pulp in association with the production thereof, where a suspension of the pulp preferably has a concentration exceeding 8% of cellulose-containing fiber material and where the pulp entering into a bleaching line is preferably fed continuously through at least one bleaching vessel in the bleaching line, is treated with at least one acid for adjusting the pH to a value below 7, and with a chelating agent, and is subsequently bleached in at least one stage to a brightness exceeding 75% ISO, preferably exceeding 80%, with hydrogen peroxide or the corresponding quantity of another peroxide, employed in a quantity exceeding 5 kg/BDMT, where the peroxide bleaching takes place at elevated temperature and at a pressure in the bleaching vessel which exceeds 2 bar and where the cross-sectional area of the bleaching vessel exceeds 3 m2 and the area of the metal surface exposed towards the interior of the bleaching vessel is less than 4 V m2, where V indicates the volume in m3. |
