| 摘要 |
PROBLEM TO BE SOLVED: To reduce the operation load and increase the pulp yield by dividing the white liquor in the production of kraft pulp into the white liquor A and the white liquor B and catalytically oxidizing the white liquor A with air in the presence of a catalyst and feeding it as an oxidized white liquor A to the first pulping step and feeding the white liquor B directly as it is to the second pulping step, and recycling them. SOLUTION: In the step where kraft pulp is produced from lignocellulose through the first and second pulping steps, the white liquor is divided into the liquor A and the liquor B. The white liquor A is air-oxidized in the presence of a catalyst and fed to the first pulping step as an oxidizing white liquor including sodium hydroxide, sodium sulfide and polysulfide sulfur-containing oxidizing white liquor, while the white liquor B is directly fed to the second pulping step and circulated.
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