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A kind of pulp bleaching method

A pulp bleaching and pulping technology, which is applied in pulp bleaching, cellulose pulp post-treatment, papermaking, etc., can solve the problem of serious carbohydrate degradation and achieve the effect of improving efficiency and selectivity

Active Publication Date: 2021-09-21
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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  • A kind of pulp bleaching method
  • A kind of pulp bleaching method
  • A kind of pulp bleaching method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] Acid after alkaline cooking pulp oxygen delignification bleaching, the pulp concentration adjusting 8wt%, while adding 1wt% H (to dry pulp) of 2 SO 4 , 0.05wt% (on dry pulp) of MnO 2 , 0.5wt% (on OD pulp) of H 2 O 2 , The uniformly mixed slurry was placed within the oxygen delignification reactor lignin, adjusting the reaction pressure 0.6Mpa, the rotational speed of 180r / min, heated to 90 ℃, after adjusting the rotational speed to 300r / min, oxygen was 3 minutes speed adjusted 180r / min, a constant temperature of 90 deg.] C continued through the reaction of oxygen 80min;

[0029] After concentrating the slurry into the alkali washing treatment stage, the alkali treatment the pulp concentration adjusting section, and 6wt% was added 1wt% (on OD pulp) of NaOH, water bath temperature 50 ℃, the reaction for 30 min;

[0030] The slurry was washed and concentrated and the next one after the bleaching, the pulp concentration adjusting 6wt% and added 0.3wt% (on OD pulp) and act...

Embodiment 2

[0033] Acid after alkaline cooking pulp oxygen delignification bleaching, the pulp concentration adjusting 9wt%, while adding 1.5wt% (on dry pulp) H 2 SO 4 , 0.1wt% (on dry pulp) MnO 2 , 1wt% (on dry pulp) H 2 O 2, The slurry is uniformly mixed in the oxygen deoxidin reactor, regulating the reactor pressure 0.6 MPa, the rotational speed 190R / min, the temperature is 105 ° C, adjust the rotational speed to 310R / min, and transfer oxygen for 3 minutes after 3 minutes. 190R / min, constant temperature at 105 ° C for 90min;

[0034] After the slurry washed and concentrated, the alkali treatment segment was obtained, and the alkali treatment segment regulated the pulp concentration of 7% by weight and added 1.5 wt% (on the dry paste) NaOH, the water bath temperature was 55 ° C, and the reaction was 35 min;

[0035] After the slurry was washed and concentrated, the next paragraph bleached, regulating the pulp concentration of 6.5 wt% and added 0.6% by weight (on the dry paste) activat...

Embodiment 3

[0038] After the alkali method is cooked, the pulp is bleached, and the adjustment pulp concentration is 10% by weight, and 2 wt% (on the dry paste) H is added. 2 SO 4 0.15 wt% (for dry pulping) MNO 2 1.5 wt% (for dry pulping) h 2 O 2 The slurry is uniformly mixed into the oxygen deodoxin reactor, regulating the reactor pressure 0.6 MPa, the rotational speed of 200R / min, the temperature is increased to 120 ° C, adjust the rotation speed to 320 r / min, and the transfer of oxygen is 3 minutes after 3 minutes. 200R / min, constant temperature at 120 ° C for 100 min;

[0039] After the slurry washed and concentrated, the alkali treatment segment was concentrated, and the alkali treatment segment regulated the pulp concentration of 8% by weight and added 2 wt% (on the dry paste) NaOH, the water bath temperature was 60 ° C, and the reaction was 40 min;

[0040] After the slurry was washed and concentrated, it entered the next bleaching, regulating the pulp concentration of 7% by weig...

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Abstract

The invention discloses a novel pulp bleaching method, comprising: (1) an oxygen delignification bleaching section under acidic conditions; (2) an alkali treatment section; (3) an activation treatment section; (4) a hydrogen peroxide bleaching section; Among them, the oxygen delignification bleaching process uses H 2 SO 4 Adjust the pH of the pulp to 4~5, the added H 2 o 2 and MnO 2 Oxidative delignification and removal of transition metal ions by peroxyacids formed under acidic conditions, oxygen promotes MnO 2 converted to MnO 4 ‑ Oxidation-reduction reaction occurs with lignin to fragment lignin macromolecules and dissolve lignin macromolecules; Oxygen is reduced to HOO to crack lignin macromolecules and remove lignin. The pulp obtained by the pulp bleaching method of the invention has good quality, and the whiteness can reach more than 80% ISO. Compared with the alkaline oxygen delignification under the same process conditions, the kappa number is reduced by about 1.5, and the delignification efficiency is improved.

Description

Technical field [0001] The present invention belongs to the technical field of pulp and papermaking processes, particularly relates to a method of bleaching pulp under an acidic condition of an oxygen delignification. Background technique [0002] Now, oxygen delignification has become a mature industrial bleaching, residual lignin unbleached pulp of 1 / 3-1 / 2 may be used to remove oxygen under basic conditions without causing a severe loss of fiber strength, and the effluent contains no chlorine, and can be used for washing brownstock washing liquid can be fed to the combustion process and the chemical recovery system. However, pulp oxygen delignification also faces many challenges: (1) alkaline oxygen delignification, the carbohydrate severe degradation, oxidative degradation and alkaline peeling reaction mainly occurs, the viscosity of the pulp is greatly reduced. (2) transition metal ions (iron, copper, etc.) present in the pulp catalyzed formation hydroxyl radicals (HO ·),...

Claims

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Application Information

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