Method for manufacturing bleached pulp from a feedstock comprising recycled paper
AssigneeWestRock MWV, LLC
InventorsPeter W. HART, John D. DEJARNETTE, Fritz G. PAULSEN, Ashok K. GHOSH
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Abstract
A method for manufacturing bleached pulp from a feedstock that includes recycled paper. The method includes steps of: (1) impregnating the feedstock with cooking liquor to yield an impregnated material having a liquor-to-fiber mass ratio of at most about 4:1; (2) cooking the impregnated material to remove at least a portion of the lignin within the impregnated material, thereby yielding a cooked pulp; and (3) bleaching the cooked pulp.
Claims31
A method for manufacturing bleached pulp from a feedstock comprising recycled paper, the recycled paper comprising lignin and cellulose, the method comprising:
- impregnating the feedstock with cooking liquor to yield an impregnated material having a liquor-to-fiber mass ratio of at most about 4:1;
- cooking the impregnated material to remove at least a portion of the lignin from the impregnated material, thereby yielding a cooked pulp;
- and
- bleaching the cooked pulp.
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A method for manufacturing bleached pulp from a feedstock comprising old corrugated containers, the old corrugated containers comprising lignin and cellulose, the method comprising:
- processing the feedstock with at least one of a hogger, a cutter and a slicer to yield a reduced size feedstock;
- impregnating the reduced size feedstock with cooking liquor comprising sodium hydroxide, sodium sulfide, and water to yield an impregnated material having a liquor-to-fiber mass ratio of at most about 3:1, wherein the impregnating the reduced size feedstock comprises compressing the reduced size feedstock to achieve a compression ratio of at least 2:1, on a volume basis;
- cooking the impregnated material to a kappa number of at most about 35 to yield a cooked pulp;
- blending the cooked pulp with virgin pulp to yield a pulp blend;
- and
- bleaching the pulp blend to a GE brightness of at least about 80 percent.
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Dependencies are inferred from the claim text.