| 摘要 |
<p>Bleaching of and lignin extn. from cellulose-contg. materials such as cellulose produced from wood or grass, comprises, after treatment with chlorinated chemicals, a step (I) in which alkali is added with oxygen, with mixing, to the pulp to form small bubbles and extract the lignin. According to the improvement that step (I) is effected after the alkaline extn. step which follows treatment with the chlorinated chemicals and the pulp so obtained is conveyed to a bleaching tower without pressure and with upward flow. The lignin remaining in the pulp can be removed after the alkaline extn. The luminosity of the pulp can be increased by treating the alkaline pulp with 02 at such a low pressure that the treatment can be effected in an ordinary bleaching tower without pressure and at a lower temp. than normally used.</p> |
