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Method for bleaching paper pulp

A pulp bleaching and pulp technology, which is applied in pulp bleaching, cellulose pulp post-processing, papermaking, etc., can solve problems such as serious carbohydrate degradation

Active Publication Date: 2019-05-10
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In order to solve the problems such as severe degradation of carbohydrates in the existing alkaline oxygen delignification bleaching process, the present invention provides a novel acidic oxygen delignification method

Method used

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  • Method for bleaching paper pulp
  • Method for bleaching paper pulp
  • Method for bleaching paper pulp

Examples

Experimental program
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Effect test

Embodiment 1

[0028] After alkaline cooking, the pulp is bleached by acidic oxygen delignification, and the pulp concentration is adjusted to be 8wt%, while adding 1wt% (to absolute dry pulp) H 2 SO 4 , 0.05wt% (to absolute dry pulp) of MnO 2 , 0.5wt% (to absolute dry pulp) of H 2 o 2 , mix the slurry evenly and place it in the oxygen delignification reactor, adjust the reactor pressure to 0.6Mpa, and the speed to 180r / min. 180r / min, continuous oxygen reaction at a constant temperature of 90°C for 80min;

[0029] After the slurry is washed and concentrated, it enters the alkali treatment section, and the alkali treatment section adjusts the pulp concentration to 6wt% and adds 1wt% (to absolute dry pulp) NaOH, the temperature of the water bath is 50°C, and the reaction is 30min;

[0030] After the slurry is washed and concentrated, enter the next stage of bleaching, adjust the pulp concentration to 6wt%, and add 0.3wt% (to absolute dry pulp) activators tetraacetylethylenediamine and acet...

Embodiment 2

[0033] After alkaline cooking, the pulp is bleached by acidic oxygen delignification, and the pulp concentration is adjusted to 9wt%, while adding 1.5wt% (to absolute dry pulp) H 2 SO 4 , 0.1wt% (to absolute dry pulp) MnO 2 , 1wt% (to absolute dry pulp) H 2 o 2, mix the slurry evenly and place it in the oxygen delignification reactor, adjust the reactor pressure to 0.6Mpa, and the speed to 190r / min. 190r / min, continuous oxygen reaction at a constant temperature of 105°C for 90min;

[0034] After the slurry is washed and concentrated, it enters the alkali treatment section, and the alkali treatment section adjusts the pulp concentration to 7wt% and adds 1.5wt% (to absolute dry pulp) NaOH, the temperature of the water bath is 55°C, and the reaction is 35min;

[0035] After the pulp is washed and concentrated, enter the next stage of bleaching, adjust the pulp concentration to 6.5wt% and add 0.6wt% (to absolute dry pulp) activators tetraacetylethylenediamine and o-phenanthrol...

Embodiment 3

[0038] After alkaline cooking, the pulp is bleached by acidic oxygen delignification, and the pulp concentration is adjusted to be 10wt%, while adding 2wt% (to absolute dry pulp) H 2 SO 4 , 0.15wt% (to absolute dry pulp) MnO 2 , 1.5wt% (to absolute dry pulp) H 2 o 2 , mix the slurry evenly and place it in the oxygen delignification reactor, adjust the reactor pressure to 0.6Mpa, and the speed to 200r / min. 200r / min, continuous oxygen reaction for 100min at a constant temperature of 120°C;

[0039] After the slurry is washed and concentrated, it enters the alkali treatment section, and the alkali treatment section adjusts the pulp concentration to 8wt% and adds 2wt% (to absolute dry pulp) NaOH, the water bath temperature is 60°C, and the reaction is 40min;

[0040] After the slurry is washed and concentrated, enter the next stage of bleaching, adjust the pulp concentration to 7wt%, and add 1wt% (to absolute dry pulp) activator o-phenanthroline or acetamide to activate the sl...

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Abstract

The invention discloses a novel method for bleaching paper pulp. The novel method includes (1), carrying out oxygen delignification bleaching stages under acidic conditions; (2), carrying out alkali treatment stages; (3), carrying out activating treatment stages; (4), carrying out hydrogen peroxide bleaching stages. The pH (potential of hydrogen) of the paper pulp is regulated by H<2>SO<4> at theoxygen delignification bleaching stages and reaches 4-5, oxidation delignification is carried out by peroxy acid formed by added H<2>O<2> and MnO<2> under the acidic conditions, transition metal ionsare removed by the peroxy acid, oxidation-reduction reaction on lignin and MnO<4><-> converted from the MnO<2> is promoted by oxygen, and accordingly lignin macromolecules can be fragmented and dissolved out; the oxygen can be reduced to obtain HOO ,accordingly, the lignin macromolecules can be decomposed, and the lignin can be removed. The novel method for bleaching the paper pulp has the advantages that paper pulp obtained by the aid of the novel method is good in quality, the whiteness can reach 80% ISO at least, the kappa number can be lowered by approximately 1.5 as compared with alkali oxygen delignification under equivalent technological conditions, and the delignification efficiency can be improved.

Description

technical field [0001] The invention belongs to the technical field of pulping and papermaking technology, and in particular relates to a pulp bleaching method for oxygen delignification under acidic conditions. Background technique [0002] Now, oxygen delignification has become an industrialized mature bleaching technology, 1 / 3-1 / 2 of the residual lignin of unbleached pulp can be removed under alkaline conditions without causing serious loss of fiber strength, and The waste liquid does not contain chlorine and can be used for brown stock washing and the washing liquid can be sent to the alkali recovery system for treatment and combustion. However, pulp oxygen delignification also faces many challenges: (1) In alkaline oxygen delignification, carbohydrates are severely degraded, mainly alkaline oxidative degradation and peeling reactions occur, and pulp viscosity is greatly reduced. (2) The transition metal ions (iron, copper, etc.) present in the pulp can catalyze the for...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): D21C9/10D21C9/147D21C9/16
Inventor 刘明友王璐
Owner SOUTH CHINA UNIV OF TECH