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Westvaco Corp
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Westvaco Corp
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Application filed by Westvaco CorpfiledCriticalWestvaco Corp
Priority to ES8603308ApriorityCriticalpatent/ES2001456A6/en
Publication of ES2001456A6publicationCriticalpatent/ES2001456A6/en
Pulp received from the bleaching stage is (i) treated with O2 at superatmospheric pressure for three mins. at least in the presence of caustic to partially extract the pulp and then without washing is (ii) mixed with hypochlorite in the presence of caustic to complete the extraction. Alternatively hypochlorite may be added before or simultaneously with the O2 treatment. - Pref. the bleaching stage employs O2, O3, or hypochlorite, etc. under alkaline conditions or Cl2 and/or CLO2 under acid conditions. Retention time in (ii) is pref. 0.5-1 hr. and O2 partial pressure in (i) is 20 psig. Pulp consistency during (i) and (ii) is pref. 8-15 wt.% on a dry basis.
ES8603308A1986-12-051986-12-05Bleaching and delignifying cellulose pulps
ExpiredES2001456A6
(en)