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Title:
TREATMENT OF CELLULOSE MATERIAL WITH ADDITIVES WHILE PRODUCING CELLULOSE PULP
Document Type and Number:
WIPO Patent Application WO1999045191
Kind Code:
A9
Abstract:
Chemical cellulose pulp (e.g. kraft pulp) is produced with enhanced strength and/or yield using a strength or yield enhancing additive such as polysulfide or anthraquinone or its equivalents or derivatives, and in a manner that allows effective recovery/reuse of the additive so as to make the process more economical. In a continuous digester (11; 111) a low temperature and relatively low alkalinity protecting zone is provided at the top of the digester terminating with a first screen (37; 137), and a second screen (38; 138) is provided below the first screen. Between the first and second screens, prior to bulk delignification, a first counter-current zone (64, 65) is provided, and additive-containing liquid from the first screen (37; 137) is recirculated (70) to the slurry at or near the digester inlet to enhance yield or strength.

Inventors:
MARCOCCIA BRUNO S
Application Number:
PCT/US1999/004072
Publication Date:
November 11, 1999
Filing Date:
February 25, 1999
Export Citation:
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Assignee:
AHLSTROM MACHINERY INC (US)
International Classes:
D21C1/00; D21C3/02; D21C3/22; D21C3/24; D21C7/00; (IPC1-7): D21C1/00; D21C7/00
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