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Sequential bleaching process suitable for ECF short-process bleaching

A short-procedure, sequential technology, applied in pulp bleaching, cellulose pulp post-treatment, textiles and papermaking, etc., can solve the problems of high waste water pollution load, high bleaching cost, large water consumption, etc. Simple preparation process and low cost

Pending Publication Date: 2020-11-24
QILU 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 of large water consumption, high waste water pollution load, and high bleaching cost in the bleaching section, the present invention provides a sequential bleaching process suitable for elemental chlorine-free (ECF) short-program bleaching, which can reduce water consumption in the bleaching section, reduce waste water discharge load, and save Bleaching cost, meeting product quality requirements

Method used

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  • Sequential bleaching process suitable for ECF short-process bleaching
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  • Sequential bleaching process suitable for ECF short-process bleaching

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] Proceed as follows:

[0031] (1) The cooking condition of eucalyptus kraft pulp is: the amount of alkali used is 21% (relative to the absolute dry raw material NaO 2 ), the liquid ratio is 1:5, the degree of sulfidation is 25%, the cooking temperature is 170°C, a small degassing is carried out at 105°C, the heating time is 100min, and the holding time is 90min; after cooking, washing and screening are carried out to obtain unbleached kraft pulp .

[0032] (2) Oxygen delignification conditions are: adjust the pulp concentration to 10%, add NaOH consumption 3%, MgSO 4 The dosage is 0.6%, the oxygen pressure is 0.6Mpa, the temperature is 100°C, and the holding time is 60min; then washing is carried out to obtain oxygen delignified pulp.

[0033] (3) Papermaking: The natural color pulp after eucalyptus kraft cooking and the pulp after oxygen delignification were beaten to 35 ° SR respectively, and then the pulp fibers were decomposed in the defiberizer to make them evenly...

Embodiment 2

[0038] Proceed as follows:

[0039] (1) X / Z / D or X / D / Z sequential bleaching: carry out sequential bleaching to the eucalyptus kraft pulp after oxygen delignification in embodiment 1, X is xylanase auxiliary bleaching; Z is ozone Bleaching; D is chlorine dioxide bleaching. The pulp is sequentially bleached with xylanase, ozone and chlorine dioxide without washing in between.

[0040] First, xylanase is used to assist bleaching of pulp, the process conditions are pulp concentration 10%, the dosage of xylanase is 5u / g, 10u / g, 15u / g, pH=5, bleaching temperature 55°C, bleaching The time is 60 minutes. Then carry out ozone bleaching, the process condition is pulp concentration 10%, pH=2, 55 ℃, bleaching time 5min, ozone consumption 1.0%, ethylene glycol consumption 2%. Finally, chlorine dioxide bleaching is carried out, and the process conditions are 10% pulp concentration, ClO 2 The dosage is 0.2%, the pH=2~3, the bleaching temperature is 55°C, and the bleaching time is 30min. ...

Embodiment 3

[0046] Proceed as follows:

[0047] (1) X / Z / D or X / D / Z sequential bleaching: carry out sequential bleaching to the eucalyptus kraft pulp after oxygen delignification in embodiment 1, X is xylanase auxiliary bleaching; Z is ozone Bleaching; D is chlorine dioxide bleaching. The pulp is sequentially bleached with xylanase, ozone and chlorine dioxide without washing in between.

[0048] First, use xylanase to assist bleaching of paper pulp. The technological conditions are pulp concentration 12%, xylanase dosage 10u / g, pH=5, bleaching temperature 60°C, and bleaching time 60min. Then carry out ozone bleaching, the technological conditions are pulp concentration 10%, pH=2, 60 ℃, bleaching time 5min, ozone consumption is respectively 0.5%, 0.75%, 1.0%, ethylene glycol consumption 2%. Finally, chlorine dioxide bleaching is carried out, and the process conditions are 10% pulp concentration, ClO 2 The dosage is 0.3%, the pH=2.5, the bleaching temperature is 60°C, and the bleaching ti...

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Abstract

The invention belongs to the technical field of papermaking, and relates to a sequential bleaching process suitable for ECF short-process bleaching. The bleaching process is short, the number of bleaching sections is small, paper pulp among the bleaching sections is not washed with water, and the process is environmentally friendly, economical and effective. The short-process comprises the following steps: firstly, carrying out xylanase-assisted bleaching (X) on unbleached paper pulp, then adjusting the pH value of the paper pulp, adding an auxiliary agent, carrying out ozone bleaching (Z), and carrying out chlorine dioxide bleaching (D) after the ozone bleaching is finished, namely the bleaching process is carried out in an X / Z / D sequence; or after xylanase treatment (X), performing chlorine dioxide bleaching (D) and ozone bleaching (Z) in sequence, namely the bleaching process is carried out in an X / D / Z sequence. According to the sequential bleaching process, the three bleaching agents are not washed, and the whiteness of paper pulp can be improved by 30% ISO or above.

Description

technical field [0001] The invention belongs to the technical field of papermaking, and in particular relates to a sequential bleaching process suitable for elemental chlorine-free (ECF) short-program bleaching. Background technique [0002] The statements herein merely provide background information related to the present invention and may not necessarily constitute prior art. [0003] The pulp and paper industry is the "sunrise industry" of the 21st century, one of the basic industries of the national economy, closely related to social development and people's lives, and occupies an important position in the global industrial manufacturing industry. In recent years, the total output of paper and paperboard in my country has shown an upward trend. Since 2012, the output and consumption of paper and cardboard in my country has ranked first in the world, but the paper industry is facing problems such as shortage of fiber resources and increasingly severe environment. Researc...

Claims

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Application Information

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IPC IPC(8): D21C9/10D21C9/14D21C9/153
CPCD21C9/1057D21C9/1026D21C9/144D21C9/153
Inventor 杨桂花陈嘉川张凯吉兴香田中建高其超
Owner QILU UNIV OF TECH
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