To provide a high-bleaching oxidized white liquor widely usable as an alkali source in the oxidation bleaching stage (oxygen delignification stage) of the initial stage of pulp bleaching sequence, alkali extraction stage, or the like, recyclingly used as a washing liquid in a pulp washer in the kraft digestion step, the wash filtrate from the bleaching stage(s), and recoverable as white liquor (white water) by reclaiming treatment as a black liquor from the pulp washer, and to provide a method for producing the high-bleaching oxidized white liquor.
The oxidized white liquor is prepared by oxidation treatment with a peroxide of a white liquor or oxidation liquor used in a kraft digestion process. In the oxidized white liquor thus prepared, the molar ratio of the amount of sulfur derived from thiosulfate ions to the total amount of sulfur is 25% or less. The method for producing the objective oxidized white liquor for an alkali source in pulp-bleaching stage is thus provided. In the method, at least one of peroxides to be used is hydrogen peroxide; and the white liquor or oxidized white liquor may be a white liquor reclaimed from the black liquor in the kraft-process digestion step or may be an oxidized white liquor obtained by subjecting the white liquor to oxygen oxidation, respectively.
| WO/2021/198558 | HYDROLYSIS OF CELLULOSE ESTERS |
| WO/2020/121140 | FRACTIONATION OF CRUDE TALL OIL |
TAKAKUSAKI EMI
UCHIDA YOSUKE
