| 摘要 |
Solvent pulping is practised using ethanol, methanol, formic acid, or the like by passing the organic solvent countercurrent to the cellulosic fibrous material (wood) being adjusted into paper pulp. The process may be batch or continuous. The pH of the process is relatively stable and neutral, and can be controlled to maintain the process generally neutral by removing the acids formed at the beginning of the cook, e.g. with spent solvent, and can be made more uniform by adding alkali to the wood just prior to the wood coming into countercurrent contact with the organic solvent. A catalyst, such as an earth-alkali metal salt or an organic base, may also be added to the wood to enhance dissolution of the ligning. The treated pulp is washed, and the solvent in the wash liquid from the washing stage may be separated by distillation. The pulp may be steamed prior to cooking. The lignin containing liquid (spent organic solvent) may also be distilled, with the organic solvent renturned to the cook, the water separated and reused, and the lignin combusted. |
