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
Life of this patent
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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.
Claims20
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, wherein the impregnating the feedstock comprises compressing the feedstock, wherein the compressing the feedstock achieves a compression ratio greater than 1:1, on a volume basis;
- determining a cooking liquor uptake of the feedstock at the compression ratio achieved during the impregnating;
- and
- tuning a charge of the cooking liquor added to the feedstock during the impregnating based on the cooking liquor uptake of the feedstock and a concentration of the cooking liquor;
- 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.
A method for manufacturing bleached pulp, the method comprising:
- providing a feedstock comprising recycled paper, the recycled paper comprising lignin and cellulose, wherein the feedstock has a solids content of at least 70 percent by weight;
- compressing the feedstock having the solids content of at least 70 percent by weight, thereby yielding a compressed feedstock;
- impregnating the compressed feedstock with cooking liquor to yield an impregnated material having a liquor-to-fiber mass ratio of at most about 4:1;
- feeding the impregnated material having the liquor-to-fiber mass ratio of at most about 4:1 to a digester;
- cooking the impregnated material having the liquor-to-fiber mass ratio of at most about 4:1 to remove at least a portion of the lignin from the impregnated material, thereby yielding a cooked pulp;
- and
- bleaching the cooked pulp.
A method for manufacturing bleached pulp, the method comprising:
- providing a feedstock comprising recycled paper, the recycled paper comprising lignin and cellulose, wherein the feedstock has a solids content of at least 70 percent by weight;
- compressing the feedstock having the solids content of at least 70 percent by weight, thereby yielding a compressed feedstock;
- impregnating the compressed feedstock having the solids content of at least 70 percent by weight, thereby yielding an impregnated material having a liquor-to-fiber mass ratio of at most about 2.5:1;
- feeding the impregnated material having the liquor-to-fiber mass ratio of at most about 2.5:1 to a digester;
- cooking the impregnated material having the liquor-to-fiber mass ratio of at most about 2.5:1 to remove at least a portion of the lignin from the impregnated material, thereby yielding a cooked pulp;
- and
- bleaching the cooked pulp.
Dependencies are inferred from the claim text.