Paper pulp bleaching process

A pulp bleaching and process technology, applied in the field of pulp bleaching process, can solve problems such as high water consumption, paper industry pollution, etc., and achieve the effects of improving pulp yield, pulp polymerization degree, and folding endurance.

Inactive Publication Date: 2003-03-12
QILU UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] The purpose of the present invention is to provide a new bleaching process to replace the traditional CEH...

Method used

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  • Paper pulp bleaching process

Examples

Experimental program
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Effect test

Embodiment 1

[0040] Caustic soda-anthraquinone wheat straw pulp (potassium permanganate value 10) is bleached according to the following steps:

[0041] ① Section H: The concentration of straw pulp is 8%, and sodium hypochlorite is added to the straw pulp to have

[0042] Calculated effective chlorine, 5.5% (weight), initial pH 11.0, temperature 50

[0043] ℃, time 60min

[0044] ②Washing with water

[0045] ③ Section D: The concentration of washed straw pulp is 8%, and chlorine dioxide is added.

[0046] 0.7% (weight), initial pH 4.5, temperature 70°C, time 150min,

[0047] End point pH6.5

[0048] ④Washing and then papermaking process

[0049] Results: The whiteness is above 75% ISO, the fracture length is 6.8km, and the folding resistance is 220 times. Compared with CEH bleaching, it saves 30% of water, reduces COD by 50%, and reduces chroma by 70%.

Embodiment 2

[0051] In Example 1, if the HD section is not washed, the amount of chlorine dioxide is increased to 1.2%, the pulp concentration is reduced to 6%, other processes remain unchanged, and the quality index of bleached pulp remains basically unchanged, saving more than 60% of water. Example 3:

Embodiment 3

[0052] Caustic soda-anthraquinone wheat straw pulp (potassium permanganate value 12), bleach according to the following steps:

[0053] ① Section H: The concentration of straw pulp is 12%, and sodium hypochlorite is added to the straw pulp to obtain available chlorine.

[0054] Calculated, it is 7% (weight), the initial pH is 12, the temperature is 60℃, and the time is 30min

[0055] ②Washing with water

[0056] ③ Section D: The concentration of the straw pulp after washing is 12%, and chlorine dioxide is added in the amount of straw

[0057] 0.5% of pulp weight percentage, initial pH4, temperature 70℃, time 150min, final

[0058] Point pH6

[0059] ④Washing and then papermaking process. Results: whiteness above 75% ISO, length of rupture 6.0km, folding resistance 180 times, compared with CEH bleaching, 30% water saving, 50% reduction in COD, and 70% reduction in chroma .

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Abstract

A process for bleaching paper pulp includes such steps as adding hypochlorite, prebleaching at 30-60 deg.C for 30-150 min, water washing, adding ClO2, bleaching and water washing. Its advantages are low pollution and low consumption of water.

Description

[0001] (1) The technical field [0002] The invention belongs to a pulp bleaching process, and particularly relates to a low-pollution and low-water consumption pulp bleaching process. (2) Background technology [0003] my country is a non-wood pulp, especially a large producer of straw pulp, accounting for more than 60% of the world's total non-wood pulp. Non-wood pulp pulping black liquor is basically treated by burning alkali recovery, but the middle-stage wastewater of pulping (mainly bleaching wastewater) adopts the traditional CEH (chlorination-alkali treatment-hypochlorite bleaching) process. There are also the following problems: [0004] (1) The amount of AOX produced in wastewater is large, about 5Kg or more per ton of slurry. AOX can adsorb organic halogens. Its main component is chlorinated phenols. Since the 1980s, it has been found to contain dioxin, a highly toxic substance. Dioxin is known to be the most toxic among toxicants. It has carcinogenicity, mutagenicity, t...

Claims

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Application Information

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IPC IPC(8): D21C9/12
Inventor 陈嘉川杨桂花
Owner QILU UNIV OF TECH
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