CN105463898A - Bleaching method of papermaking slurry - Google Patents
Bleaching method of papermaking slurry Download PDFInfo
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- CN105463898A CN105463898A CN201410417694.9A CN201410417694A CN105463898A CN 105463898 A CN105463898 A CN 105463898A CN 201410417694 A CN201410417694 A CN 201410417694A CN 105463898 A CN105463898 A CN 105463898A
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Abstract
Belonging to the technical field of papermaking, the invention in particular relates to a bleaching method of papermaking slurry. The bleaching method of papermaking slurry comprises the steps of: 1) adjusting the pH value of a slurry with a weight percent concentration of 3-5% to 8-9, adding a bleaching agent, introducing saturated steam under stirring, subjecting the slurry to reaction under a temperature condition of 83DEG C-85DEG C for 5-8min, wherein the bleaching agent and the slurry are in a weight percentage ratio of 8-10%; and 2) impregnating the slurry treated by step 1) under stirring, and carrying out impregnation reaction for 20-30min. The method determines the control range of more suitable bleaching temperature, and solves the problems of whiteness yellowing and whiteness reduction.
Description
Technical field
The invention belongs to pulp technology for making paper, be specifically related to a kind of method for bleaching of paper grade (stock) slurry.
Background technology
Containing cellulose, hemicellulose and lignin in the slurry of paper grade (stock).In the method that a series of delignification for paper pulp used in the prior art and bleaching are fitted, a lot of is all the chemical pulp obtained by the boiling to the cellulosic-based material in slurry under the existence of chemical reactor, and use has oxidative chemistries in these processing procedures.Usually, in the first stage of the chemical process of association with pulp bleaching, be to improve the delignification not floating paper pulp obtained from steaming stage.This delignification stage is normally with adding chlorine in acid condition, chlorine dioxide or brown stock is carried out with both mixture, to react with the residual lignin in paper pulp, and by dissolution subsequently processing stage in paper pulp purified out make product.But owing to relating to the various reasons of enhancement of environment, start gradually adopt to environment more favorably without chlorine chemistry reaction reagent, replace chloride chemical reactor in large quantities.
In the materials such as the cellulose contained in the slurry, hemicellulose and lignin, lignin should be removed by bleaching process in bleaching process.In traditional treatment process, under the condition of oxidising agent, bleaching temperature is controlled at 80 degree, and removes gradually in the reaction.But based on the control of existing bleaching temperature, the cellulose in slurry and hemicellulose are bleached substantially abundant, and lignin machine group can not fully emanate, thus cause slurry seemingly to float the situation of non-drift.Its result is exactly the easy brightness reversion of slurry, places whiteness after 24 hours and reduces by 5 ~ 6%.Simultaneously, slurry directly goes out from bleaching machine is straight, slurry can be subject to the impacts such as concentration, proportioning, body paper primary colours, short with bleaching liquid incorporation time, slurry bleaching is insufficient, causes pulp brightness inconsistent, pulp brightness Gao Keda more than 88%, low only has about 80%, becomes " the half-cooked biscuit " of uneven distribution between height whiteness.
Summary of the invention
For solving the deficiencies in the prior art, the invention provides a kind of method for bleaching of paper grade (stock) slurry.The method determines the control range of more suitable bleaching temperature, solves a difficult problem for whiteness brightness reversion and whiteness reduction in the lump.Further, by slurry after bleaching, introduce impregnation treatment stage, make slurry and liquid sufficient reacting, and use stir process further, slurry and bleaching agent even contact are bleached, solve slurry " half-cooked biscuit " phenomenon.
A method for bleaching for paper grade (stock) slurry, comprises the following steps:
1) by concentration expressed in percentage by weight be 3 ~ 5% the pH value of slurry be adjusted to 8 ~ 9, slurry is by delivering to the import of heat dispersion machine with stock pump, import department adds bleaching agent therewith, and pass into saturated vapor, slurry is reacted in a device under the temperature conditions of 83 DEG C ~ 85 DEG C, and slurry approximately needs 5 ~ 8 minutes from import in a device to outlet, is also the slurry reaction time in a device, wherein, the percentage by weight of described bleaching agent and described slurry is 8 ~ 10%.
2) by through step 1) process the slurry obtained and enter impregnation bin by gravity flow and carry out impregnation, impregnation bin is equipped with transport, and slurry is 20 ~ 30 minutes from entering impregnation bin to the time going out impregnation bin, and therebetween, slurry is fully bleached.
Preferably, described step 1) in described bleaching agent be hydrogen peroxide, for avoiding hydrogen peroxide to decompose in bleaching process, while adding hydrogen peroxide, add the stabilizing agents such as chelating agent, sodium metasilicate, magnesia to improve bleaching effect.
Preferably, described step 1) in mixing time be that slurry enters and the time gone out at equipment, namely 5 ~ 8 minutes, described step 2) in time of described stirring be the time that slurry proceeds to out at impregnation bin, namely 20 ~ 30 minutes.
Detailed description of the invention
Be described principle of the present invention and feature below, example, only for explaining the present invention, is not intended to limit scope of the present invention.
Embodiment 1
By concentration expressed in percentage by weight be 4% slurry mix with bleaching agent hydrogen peroxide, regulate pH to 8, in heat dispersion machine, pass into saturated vapor, slurry is reacted under the temperature conditions of 84 DEG C, reaction time is 6 minutes, and wherein, the percentage by weight of described bleaching agent and described slurry is 9%.
By through step 1) process the slurry obtained and flood, dip time is 6 minutes, obtains the slurry bleached.
The whiteness of the slurry of the bleaching more than prepared is 88%, delignification rate 85%, and place 24 hours, whiteness is brightness reversion not.
Comparative example 1
Be that 4% slurry mixes with bleaching agent hydrogen peroxide by concentration expressed in percentage by weight, regulate pH to 8, in heat dispersion machine, pass into saturated vapor, slurry is reacted under the temperature conditions of 81 DEG C, reaction time is 6 minutes, and wherein, the percentage by weight of described bleaching agent and described slurry is 9%.
By through step 1) process the slurry obtained and flood, the time is 8 minutes, obtains the slurry bleached.
The whiteness of the slurry of the bleaching more than prepared is stabilized in 82%, and delignification rate is 75%, and whiteness is low, and namely slurry starts anti-Huang after placing 16 hours.
Comparative example 2
Be that 5% slurry mixes with bleaching agent hydrogen peroxide by concentration expressed in percentage by weight, regulate pH to 9, in heat dispersion machine, pass into saturated vapor, slurry is reacted under the temperature conditions of 90 DEG C, reaction time is 6 minutes, and wherein, the percentage by weight of described bleaching agent and described slurry is 9%.
By through step 1) process the slurry obtained and flood, dip time is 6 minutes, obtains the slurry bleached.
The whiteness of the slurry of the bleaching more than prepared is 89%, delignification rate 80%, places 12 hours, and whiteness brightness reversion is serious, and slurry loss is serious, and cost is high.
Can be found out by above embodiment and comparative example, based on the temperature controlling range of (84 ± 1) provided by the present invention DEG C, can keep, in high whiteness situation, solving anti-yellow problem after placing, Be very effective.
The foregoing is only better embodiment of the present invention, not in order to limit the present invention, within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (3)
1. a method for bleaching for paper grade (stock) slurry, is characterized in that, comprises the following steps:
1) by concentration expressed in percentage by weight be 3 ~ 5% the pH value of slurry be adjusted to 8 ~ 9, add bleaching agent, pass into saturated vapor under agitation, slurry is reacted under the temperature conditions of 83 DEG C ~ 85 DEG C, reaction time is 5 ~ 8 minutes, wherein, the percentage by weight of described bleaching agent and described slurry is 8 ~ 10%;
2) by through step 1) process the slurry obtained and flood under agitation, the impregnation time is 20 ~ 30 minutes.
2. the method for bleaching of paper grade (stock) slurry according to claim 1, is characterized in that: described step 1) in described bleaching agent be hydrogen peroxide.
3. the method for bleaching of paper grade (stock) slurry according to claim 1 or 2, is characterized in that: described step 1) in mixing time be 5 ~ 8 minutes, described step 2) in mixing time be 20 ~ 30 minutes.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410417694.9A CN105463898A (en) | 2014-08-23 | 2014-08-23 | Bleaching method of papermaking slurry |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410417694.9A CN105463898A (en) | 2014-08-23 | 2014-08-23 | Bleaching method of papermaking slurry |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN105463898A true CN105463898A (en) | 2016-04-06 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201410417694.9A Pending CN105463898A (en) | 2014-08-23 | 2014-08-23 | Bleaching method of papermaking slurry |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN105463898A (en) |
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2014
- 2014-08-23 CN CN201410417694.9A patent/CN105463898A/en active Pending
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| C06 | Publication | ||
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| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20160406 |
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| WD01 | Invention patent application deemed withdrawn after publication |