Process for increasing pulp whiteness by bleaching printed wastepaper under intense dispersing mechanical treatment
AssigneeVoith Sulzer Stoffaubereitung GmbH
InventorsVolker Gehr, Harald Selder
Life of this patent
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Abstract
A process for increasing a degree of whiteness of paper pulp may include bring paper fiber pulp, which may at least partially include printed waste paper, into a suspension with water. The suspension may be mixed with bleaching aids and bleaching chemicals. The bleaching chemicals may preferably contain molecular oxygen. Intensely mechanically treating the pulp, e.g., at at least 20 kWh/to, prior to bleaching the pulp suspension. The bleaching period may take at least 10 minutes, with a pressure above the atmospheric pressure being exerted during the bleaching. After bleaching, a major portion of remaining color print particles may be removed from the bleached pulp.
Claims37
A process for increasing a degree of whiteness of paper pulp, the paper pulp including printed waste paper in which print includes color print particles, the process comprising:
- producing a suspension including the paper pulp and water;
- blending bleaching aids into the suspension;
- adding bleaching chemicals to the suspension;
- bleaching said suspension under a pressure of at least approximately one bar for at least approximately ten minutes;
- subjecting said suspension, either prior to or during or after said bleaching, to an intense dispersing mechanical treatment at a specific work of at least approximately 20 kWh/to, to a pulp consistency greater than approximately 15% and a pulp temperature above approximately 40.degree. C.;
- and
- removing a major portion of print color particles separated from said suspension.
A process for increasing a degree of whiteness of paper pulp including printed waste paper in which print includes color print particles, the process comprising:
- producing a suspension comprising the paper pulp;
- bleaching said suspension with bleaching aids and bleaching chemicals added to said suspension;
- subjecting said suspension, either prior to or during or after said bleaching, to an intense dispersing mechanical treatment at a specific work of at least approximately 20 kWh/to;
- removing a portion of print color particles separated from said suspension;
- and
- the adding of the bleaching aids and bleaching chemicals comprising:
- adding bleaching aids at at least one of during producing of the suspension, during subjecting of said suspension to the specific work, and between the producing of the suspension and the subjecting of said suspension to the specific work;
- and
- adding bleaching chemicals at at least one of during subjecting of said suspension to the specific work and during the bleaching.
Dependencies are inferred from the claim text.