| 摘要 |
The bleaching sequences of the multiple-stage process begin with an alkaline peroxide digestion. In particular, for the bleaching of hard wood pulps, a partial chlorination and extraction stage can follow the alkaline peroxide digestion or a partial chlorination can be carried out before the alkaline peroxide digestion. For the partial chlorination and extraction stages, only about 20% of the amount of chlorine previously used or 50% of the amount of alkali previously used is required. The bleaching liquors and bleaching waste water produced from the first stage, or, when partial chlorination is used before the peroxide digestion, from the first two stages, can be fed directly to a regeneration plant, by-passing the outfall. The process can be carried out at normal atmospheric pressure on the conventional devices, and in the peroxide bleaching stages, no water glass is required.
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