| 摘要 |
<p>A method of oxygen delignification of pulp from lignocellulosic material at medium concentration in two steps. An extended delignification is obtained in that the temperature in the first step is held below 90 °C, that the difference in temperature between the steps is lower than 20 °C. The pressure in the first step is 4-10 bar and in the second step 2-5 bar, and the pressure in the first step is higher than in the second step. The oxygen addition to the first step is high, 25-50 kg/ton pulp, that alkali is added only to the first step for obtaining high alkalinity in the pulp, 25-50 kg alkali per ton pulp. The stay-time in the first step is 10-30 min and in the second step 45-180 min.</p> |
