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High-pressure hydrogen peroxide bleaching method of soda pulp

A technology of hydrogen peroxide and pulp, which is applied in the field of paper pulp bleaching to achieve the effect of improving efficiency

Inactive Publication Date: 2002-03-27
黄干强 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0011] In the middle and late 1990s, the method of bleaching chemical pulp with pressure hydrogen peroxide began to appear abroad, and the bleaching conditions were as follows: H 2 o 2 The bleaching reaction is increased from normal pressure to about 0.5Mpa, and the reaction temperature is also increased to about 110-120°C. At this time, the delignification effect is greatly improved, and the pulp brightness can be increased by 30-35 brightness units (wood pulp), but The reaction time still needs about 3 hours

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] Embodiment one NaOH-AQ wheat straw pulp bleaching

[0027] 1. Properties of natural wheat straw pulp:

[0028] Kappa number 10~12, whiteness 37~38%ISO, viscosity 1050~1180ml / g

[0029] 2. Bleaching process:

[0030] In the first step, the washed uncolored pulp is pretreated with ethylenediaminetetraacetic acid (EDTA) with a mass percent concentration of 0.2%, and then washed with water.

[0031] In the second step, in the pulp after pretreatment, adding mass percentage concentration is 2% Na respectively 2 Sio 3 , 3% NaOH, 0.5% MgSO 4 and 4% H 2 o 2 , and then use the medium-consistency pump to send the pulp into the medium-consistency pulp mixer, add oxygen and steam into the medium-consistency pulp mixer, and then send the pulp to the hydrogen peroxide bleaching tower after passing through the mixer, and the pulp stays in the bleaching tower for 60 minute.

[0032] Reaction process conditions: the reaction pressure is 1.2Mpa, the reaction temperature is 125°C,...

Embodiment 2

[0035] Example disulfate eucalyptus pulp bleaching

[0036] 1. Properties of the color paste:

[0037] Kappa number 20, whiteness 39% ISO, viscosity 1179ml / g

[0038] 2. Bleaching process:

[0039] In the first step, the washed uncolored pulp is pretreated with diethylenetriaminepentaacetic acid (DAPA) with a mass percent concentration of 0.3%, and then washed with water.

[0040]In the second step, in the pulp after pretreatment, adding mass percent concentration is 3% Na respectively 2 Sio 3 , 2.5% NaOH, 0.5% MgSO 4 and 3% H 2 o 2 , and then use the medium-consistency pump to send the pulp into the medium-consistency pulp mixer, add oxygen and steam into the medium-consistency pulp mixer, and then send the pulp to the hydrogen peroxide bleaching tower after passing through the mixer, and the pulp stays in the bleaching tower for 50 minute.

[0041] Reaction process conditions: the reaction pressure is 2.0Mpa, the reaction temperature is 110°C, and the mass percent co...

Embodiment 3

[0044] Example trisulfate Caribbean loose pulp

[0045] 1. Properties of the color paste:

[0046] Kappa number 24.5%, whiteness 23% ISO, viscosity 935ml / g

[0047] 2. Bleaching process:

[0048] In the first step, the washed uncolored pulp is pretreated with ethylenediaminetetraacetic acid (EDTA) with a mass percent concentration of 0.3%, and then washed with water.

[0049] In the second step, in the pulp after pretreatment, adding mass percent concentration respectively is 4% Na 2 Sio 3 , 3% NaOH, 0.5% MgSO 4 and 5% H 2 o 2 , and then use the medium-consistency pump to send the pulp into the medium-consistency pulp mixer, add oxygen and steam into the medium-consistency pulp mixer, and then send the pulp to the hydrogen peroxide bleaching tower after passing through the mixer, and the pulp stays in the bleaching tower for 60 minute.

[0050] Reaction process conditions: the reaction pressure is 0.9Mpa, the reaction temperature is 130°C, and the mass percent concentr...

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Abstract

The high-pressure hydrogen peroxide bleaching method for alkali pulp includes the following steps: using chelating agent to pretreat pulp, then respectively adding Na2SiO3, NaOH, MgSO4 and H2O2, thenusing medium concentration pulp pump to pump the pulp into the medium concentration pulp mixer, adding oxygen gas and steam into the medium concentration pulp mixer, adding oxygen gas and steam into medium concentration pulp mixer after the pulp is passed through the mixer, feeding the pulp into hydrogen peroxide bleaching tower, then feeding the pulp into pulp washing machine, then washing and cleaning. Said invention raise reaction pressure and reaction temp. for bleaching pulp, and greatly raises bleaching efficiency, and its waste water contains no chlorinated organics, and can be recovered by recovering procedure, so it implements the "zero discharge" of beaching waste water.

Description

(1) Technical field [0001] The invention relates to the technical field of pulp bleaching in papermaking, in particular to a high-pressure hydrogen peroxide bleaching method for alkaline pulp. (2) Background technology [0002] Since the chlorination of elemental chlorine was used as the first stage of kraft pulp bleaching in 1930, almost all bleaching methods for producing high-brightness pulp start with two stages of chlorination (C) and alkali extraction (E). This is because the combination of C and E is the most economical and effective way to bleach chemical pulp. However, in 1985, the U.S. Environmental Protection Agency detected 2,3,7,8-tetrachlorodiphenyl-p-dioxin (TCDD) in fish caught in the downstream of some pulp mill rivers, which caused great concern in various countries. . The most effective way to eliminate organic chloride in bleaching wastewater is to reduce or eliminate pulp bleaching with chlorine. Therefore, in the mid-to-late 1980s, improved kraft ste...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): D21C9/16
Inventor 黄干强张曾
Owner 黄干强
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