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Method for consecutive blanching flax paper pulp in high whiteness through multiple stage

A high-brightness, pulp technology, applied in the field of pulp bleaching, can solve the problems of high production cost, low whiteness of bleached pulp, large discharge, etc., achieve low environmental pollution load, improve pulp quality, and reduce waste water discharge. Effect

Inactive Publication Date: 2006-12-06
MUDANJIANG HENGFENG PAPER CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] (1) The brightness of bleached pulp is low (below 75% ISO), and it is impossible to achieve high brightness (above 85% ISO), and the yellowing is serious, and it is impossible to make high-grade paper products. To improve the apparent brightness of pulp, it is necessary to add fluorescence Whitening agent, and fluorescent whitening agent is a carcinogenic chemical, which is now banned in the fields of paper such as medical hygiene and food packaging
[0004] (2) Due to the use of intermittent bleaching, the production efficiency is low, the quality index fluctuates greatly, the labor intensity of the workers is high, and the consumption of water, electricity, steam and chemicals per ton of finished products is large, resulting in high production costs
[0005] (3) Waste water cannot be recycled, and the discharge volume is large
[0006] In the existing bleaching methods of flax pulp, there is no bleaching technology to produce high brightness (more than 85% ISO), no continuous bleaching production mode, no activation pretreatment (S), no activation pretreatment and hydrogen peroxide (P) bleaching The combination

Method used

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  • Method for consecutive blanching flax paper pulp in high whiteness through multiple stage

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Experimental program
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Effect test

specific Embodiment approach 1

[0033] Specific embodiment one: in conjunction with Fig. 1, the flax pulp continuous multistage bleaching method of the present embodiment comprises the following steps:

[0034] 1. Cooking, washing and grinding

[0035] After the flax raw material is cooked by the alkaline sulfite method, the cooked slurry is fully washed and cut by the washing machine, and the impurities are removed by screening and purification equipment, and the slurry after the removal of impurities is adjusted to be suitable for storage The concentration is put into the semi-slurry buffer tank.

[0036] 2. Chlorination (C)

[0037] After washing, grinding, screening, and purification, the pulp and chlorine gas are fully mixed and then enter the chlorination tower. The chlorine gas reacts with the residual lignin in the pulp, and the lignin degrades into fragments soluble in water or dilute lye. The viscosity of the pulp is reduced, and the carbohydrates are degraded to a certain extent. Only a part of ...

specific Embodiment approach 2

[0042] Specific embodiment two: put 3000 kg of absolute dry flax raw materials, sulfite, sodium hydroxide and a certain proportion of water into the digester, and cook at a temperature of 168-170°C for a certain period of time to obtain unbleached flax pulp. After washing, grinding, screening and purification, after four stages of continuous bleaching including chlorination (C), alkali treatment (E), pretreatment (S) and hydrogen peroxide (P), high whiteness flax pulp (whiteness 85% ISO or above), the specific conditions are as follows:

[0043] 1. Cooking conditions (Table 1):

[0044] Nabeji

1

2

3

4

Pot loading time (h)

2.0

2.0

2.0

2.0

raw material

quality

Condition

Bone content (%)

4.6

4.6

4.6

4.6

Short fiber content (%)

14.3

14.3

14.3

14.3

Average pile length (mm)

53

53

53

53

Alkali ratio (%) ...

specific Embodiment approach 3

[0081] Specific embodiment three: the difference between this embodiment and specific embodiment two is that the specific process conditions are as follows:

[0082] 1. Cooking process conditions:

[0083] Pot capacity: 3200±100kg;

[0084] Sodium hydroxide: 4.0%, dosage: 128kg;

[0085] Anthraquinone derivatives: 0.05%, dosage: 1.6kg;

[0086] Liquid ratio: 1:2.6, additional water: 7.8T;

[0087] Liquid temperature: 75~80℃

[0088] Cooking curve:

[0089] Dry run: 90 minutes

[0090] One heating: 60 minutes 0~0.45Mpa

[0091] Small steam release: 0.45~0Mpa in 10 minutes

[0092] Second heating: 30 minutes 0~0.65Mpa

[0093] Heat preservation: 2.5 hours 0.65~0.75Mpa

[0094] Hardness: ≤6 (Kappa value), residual alkali: only check but not control;

[0095] 2. Bleaching conditions:

[0096] (1) Section C:

[0097] Chlorine consumption: 1.0% (for absolute dry pulp);

[0098] Slurry concentration: 2.0%~3.0%;

[0099] Time: 30-40 minutes;

[0100] Temperature: room t...

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Abstract

A continuous multisection bleaching method of high whiteness flax paper pulp applies bleaching process as chlorinating-alkali treatment-activation pretreatment-hydrogen peroxide bleaching. In the method, bleaching whiteness value of single hydrogen peroxide bleaching section can be increased by 20-30% ISO.

Description

technical field [0001] The invention relates to a pulp bleaching method in the pulp and paper industry, in particular to a high-whiteness continuous multi-stage bleaching method for flax pulp in straw pulp. Background technique [0002] Flax belongs to grass plant fiber raw materials with particularly long fibers. During the pulping and bleaching process, this kind of raw materials is different from general grass plant fiber raw materials (such as wheat straw, rice straw, etc.) , reeds, etc.) are very different. Existing flax pulp bleaching method is to adopt hypochlorite (H) single stage, interval type bleaching method, and this bleaching method mainly has following problems: [0003] (1) The brightness of bleached pulp is low (below 75% ISO), and it is impossible to achieve high brightness (above 85% ISO), and the yellowing is serious, and it is impossible to make high-grade paper products. To improve the apparent brightness of pulp, it is necessary to add fluorescence W...

Claims

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Application Information

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IPC IPC(8): D21C9/10D21C9/12D21C9/16D21H21/32
Inventor 李劲松潘全利刘明友王宏瑜刘玉红刘洪伟单崎峰王世刚李玉堂
Owner MUDANJIANG HENGFENG PAPER CO LTD
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