Method for Reducing the Extractives Content of High-Yield Pulps and Method for Producing Bleached High-Yield Pulps
First Claim
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1. A method for treating pulp, said method comprising:
- peroxide bleaching the pulp;
contacting the pulp with an organic stabilizer before or during the peroxide bleaching;
contacting the pulp with a surfactant before, during or after the peroxide bleaching;
said dewatering and/or washing the peroxide bleached pulp containing the organic stabilizer and the surfactant to remove extractives along with the aqueous phase.
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Abstract
The invention relates to a method for reducing the content of extractives of a high-yield pulp in a peroxide bleaching stage, said stage including peroxide bleaching and a subsequent dewatering or washing, said method comprising contacting the pulp in the peroxide bleaching with an organic stabilizer and in or after the peroxide bleaching with a surfactant, and thereafter subjecting the bleached pulp to said dewatering or washing for removing extractives along with the aqueous phase. The invention also relates to a method for producing bleached high-yield pulp.
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Citations
22 Claims
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1. A method for treating pulp, said method comprising:
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peroxide bleaching the pulp;
contacting the pulp with an organic stabilizer before or during the peroxide bleaching;
contacting the pulp with a surfactant before, during or after the peroxide bleaching;
said dewatering and/or washing the peroxide bleached pulp containing the organic stabilizer and the surfactant to remove extractives along with the aqueous phase. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 21, 22)
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11. A method for producing a bleached having a reduced content of extractives, comprising:
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bleaching a pulp with a peroxide;
contacting the pulp with an organic, polymeric stabilizer before or during the peroxide bleaching, in an amount of 0.1 kg to 5 kg) per ton dry pulp, wherein the stabilizer comprises a poly-alpha-hydroxyacrylic acid, a salt thereof, the corresponding polylactone, a homopolymer of acrylic acid, a homopolymer of methacrylic acid, a homopolymer of malcic acid, a copolymer of acrylic acid with an unsaturated dicarboxylic acid, a copolymer of methacrylic acid with an unsaturated dicarboxylic acid, or a combination comprising at least one of the foregoing organic stabilizers;
contacting the pulp with an anionic or nonionic surfactant before the peroxide bleaching, during the peroxide bleaching, or after the peroxide bleaching in an amount of 0.1 kg to 5 kg per ton dry pulp, wherein the surfactant comprises naphthalene sulphonate, naphthalene lignosulphonate, an oil-in-water emulsifier, a fatty alcohol ethoxylate, an alkyl phenol ethoxylate, or a combination comprising at least one of the foregoing surfactants; and
dewatering and/or washing the bleached pulp to remove extractives along with the aqueous phase, to produce a bleached pulp having a reduced content of extractives. - View Dependent Claims (12, 13, 14, 15, 16, 18, 20)
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17. (canceled)
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19. (canceled)
Specification