| 摘要 |
<p>The present invention relates to treatment of pulp in connection with bleaching. The pulp is first cooked and, if necessary, oxygen delignified in order to reduce the Kappa number below 24, preferably below 14, and after that the pulp is treated in an acid stage at a pH of 2-5 and at a temperature range of 75-130 °C in order to reduce the Kappa number by 2-9 units. To prevent essential weakening of the strength properties of the pulp in the acid stage treatment tower, the retention time, t min, is 30 to 300 minutes and the treatment temperature, T °C is Tmin < T < Tmax. The invention also relates to apparatus for effecting the method.</p> |
