| 摘要 |
PROBLEM TO BE SOLVED: To aim at the improvement of the yield of a non-bleached pulp produced in a craft digestion process. SOLUTION: This method for improving the yield of a non-bleached pulp is to precipitate a part of a dissolved lignin intentionally on the pulp fiber. The holding of lignin on the pulp yields the increase of the pulp. The washing of the pulp in a series of washing stages 12, 14, 16 removes carried lignin successively. By adding diluting water between each of the washing stages, the pulp flowing out from the previous washing stage is re-pulped and the pulp flow for the next washing stage is formed. After at least one washing stage, an acidifying agent is added in the pulp flow for precipitating the carried lignin on cellulose fiber to form a pulp product having an increasedκ-value by at least 1 unit.
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