CN104032611B - A kind of dioxde pulp bleaching process - Google Patents
A kind of dioxde pulp bleaching process Download PDFInfo
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- CN104032611B CN104032611B CN201410283889.9A CN201410283889A CN104032611B CN 104032611 B CN104032611 B CN 104032611B CN 201410283889 A CN201410283889 A CN 201410283889A CN 104032611 B CN104032611 B CN 104032611B
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Abstract
The invention discloses a kind of dioxde pulp bleaching process, the method comprises: (1) supercritical CO
2extraction: after being ground by paper pulp crushing, put into supercritical CO after adding cellulose protective agent
2in extraction kettle, and add entrainer extraction, rear paper pulp is diluted to mass concentration through water washing is 15%.(2) ClO 2 bleaching: be 7-12% by pulp concentrating to concentration, initial ph value scope is 4-6, temperature is 40-90 DEG C, then aqueous solution of chlorine dioxide is added, consumption is the 0.3%-1.8% of oven dry stock quality, and bleaching time is 30-100min, and endpoint pH is 3-5, wash dereaction residue with water, obtain bleached pulp.The present invention first adopts supercritical CO
2pre-bleaching, after carry out chlorine dioxide drift again, the method can reduce chemical bleaching agent consumption, and carbon dioxide in process can be recycled, and decreases the pollution in pulp bleaching process, meets development and the requirement of the outer cleanly production of Present Domestic.
Description
Technical field
The invention belongs to pulp technology for making paper, specifically a kind of dioxde pulp bleaching process.
Technical background
Along with the increasingly stringent of environmental requirement, the harm of the chlorinated organics contained in chloro-bleaching effluents to environment causes the extensive concern of people, chlorine and hypochlorite bleaching are more and more restricted, and association with pulp bleaching is just towards the future development of element-free chlorine and total chlorine free bleaching.China's Bleaching Technology slower development, particularly the grass family such as careless class is that the Bleaching Technology of raw material is still at use hypochlorite bleaching, severe contamination environment, in other bleaching technology, also part also exists the bleaching section used containing villaumite, far can not meet the requirement of environment.
The bleaching of paper pulp acts on fiber to improve the process of its whiteness, is from slurry, remove lignin or change the structure of lignin and reach bleaching effect.Growing along with science and technology, supercritical fluid extraction cleans as one, efficient and good optionally novel separation method, after it is separated with extraction component, there is no the residual of solvent, effectively can avoid the residual of solvent toxicity under conventional solvent extraction conditions, also prevent the murder by poisoning of leaching process to human body and the pollution to environment, be a kind of natural and abstraction technique of environmental protection simultaneously.This abstraction technique is applied to papermaking bleaching process, the deficiency that in current paper industry, bleaching technology exists will be made up.In numerous supercritical fluids, carbon dioxide because its critical point temperature is low, cheap, safety, environmental protection and the advantage such as nontoxic, become the most frequently used a kind of supercritical fluid, and be used widely in the industry such as food, chemical industry.And the application of supercritical fluid technique in paper industry is also fewer, in the paper pulp bleaching process of present stage, papermaking enterprise to a great extent with full chemicals for the main bleaching carrying out paper pulp, this causes severe contamination to environment, brings obstacle also to a certain extent enterprise's industry structure change development.
Summary of the invention
The object of the invention is to improve traditional Bleaching Technology, provides a kind of new paper pulp bleaching process, to reduce the consumption of chemical bleaching medicine, makes the fiber after bleaching have high whiteness.
The present invention adopts following technical scheme to realize its goal of the invention:
Dioxde pulp bleaching process of the present invention, adopt supercritical carbon dioxide and chlorine dioxide united bleaching paper pulp, concrete operation step is as follows:
(1) supercritical CO is adopted
2extraction: after the paper pulp crushing of drying is ground, add cellulose protective agent, powder is mixed rear threading supercritical CO
2in extraction kettle, and add entrainer extraction, supercritical CO
2extraction conditions: extraction temperature is 70-110 DEG C, extracting pressure is 7-15MPa, and extraction time is 60-120min, CO
2flow velocity is 16-25L/h, and after extraction, the paper pulp in extraction kettle being diluted to mass concentration through water washing is 12-15%;
(2) ClO 2 bleaching is adopted: be 7-12% by pulp concentrating to mass concentration, initial ph value scope is 4-6, temperature controls at 40-90 DEG C, and then the disposable aqueous solution of chlorine dioxide that adds is bleached, and the mass concentration of aqueous solution of chlorine dioxide is 6-15g/L, consumption is the 0.3%-1.8% of oven dry stock quality, bleaching time is 30-100min, and endpoint pH scope is 3-5, finally washes dereaction residue with water, reach 6-7 to eluate pH value, obtain bleached pulp.
In step (1), described paper pulp is with wheat straw or straw or bamboo pulp be raw material chemical pulp or reducing rules.
In step (1), described paper pulp carries out drying in baking oven, and oven temperature is at 50-70 DEG C, and paper pulp moisture is after drying lower than 8%.
In step (1), after described paper pulp crushing, size of powder particles is at 200-450 μm.
In step (1), described entrainer is methyl alcohol, and the consumption of methyl alcohol is the 2%-5% of oven dry stock quality.
In step (1), described cellulose protective agent is MgSO
4, MgSO
4consumption is the 0.3-0.5% of oven dry stock quality.
In step (2), the preferable temperature of ClO 2 bleaching is 70 DEG C.
Supercritical extraction technique is applied in association with pulp bleaching by the present invention, the solubility of alter is carried out by the temperature and pressure in regulable control Supercritical Extraction Process, to make the low molecule extract of paper pulp, macromolecule lignin be separated with paper pulp, namely the lignin in removing paper pulp is reached by extract and separate, again paper pulp is passed through ClO 2 bleaching, obtain the paper pulp of high whiteness.
The present invention utilizes supercritical CO
2after fluid cutting out partial lignin, then strengthen pulp brightness by residual lignin in Chlorine Dioxide Oxidation paper pulp, pulp brightness can be made to reach more than 80%, and retention of whiteness is good.
The inventive method compared with prior art, has the following advantages:
(1) the invention provides a kind of more novel paper pulp bleaching process, in process, have employed supercritical CO
2abstraction technique, to fibrous zero damage, without chemical residual, CO
2can be recycled, whole technological process is low few sewage discharge.While this section of technology extraction mode plays discoloration, have also been obtained purer lignin, can be used for other purposes.This section of technology future development space is large, once replace other bleaching technologies completely, can save large water gaging, produces enormous benefits to society.
(2) supercritical CO is utilized
2extraction departs from the process of lignin, can also objectionable impurities removings such as pigments in paper pulp; ClO 2 bleaching Duan Ze further increases whiteness and the retention of whiteness of paper.
Accompanying drawing explanation
Fig. 1 is the process chart of the inventive method.
Detailed description of the invention
The inventive method is further described below in conjunction with drawings and Examples.
Embodiment 1:
The raw material of this instance processes is Straw Pulp.Choose Straw Pulp 300g, in baking oven, carry out drying, baking temperature is 50 DEG C, makes paper pulp moisture be 7%.Dried paper pulp grinds, and gets the paper pulp powder that granule size is 450 μm, adds 0.5%MgSO
4powder (relative absolute dried paper pulp quality), after stirring, puts into supercritical CO
2in extraction kettle, add methyl alcohol as entrainer, methanol usage is 5% (relative absolute dried paper pulp quality).Extracting pressure is 15MPa, temperature 110 DEG C, and extraction time is 120min, CO
2flow velocity is 25L/h.After separation, the paper pulp in extraction kettle being diluted to mass concentration through water washing is 15%, obtains just bleached pulp.Pulp density being concentrated into mass concentration is 12%, carry out ClO 2 bleaching, aqueous solution of chlorine dioxide concentration is 15g/L, and consumption is 1.8% (with the percentage of absolute dried paper pulp quality), original ph 4.5, temperature 90 DEG C, time is 100min, and drift pH is 3.5 eventually, finally washes dereaction residue with water, reach 6 to eluate pH value, obtain bleached pulp.
Result: supercritical CO
2after extraction just drift, paper pulp delignification rate is 70.2%; After ClO 2 bleaching, pulp brightness is 84%ISO.
Embodiment 2:
The raw material of this instance processes is bamboo pulp.Choose bamboo pulp 300g, in baking oven, carry out drying, baking temperature is 70 DEG C, makes paper pulp moisture be 6%.Dried paper pulp grinds, and gets the paper pulp that granule size is 200 μm, adds 0.3%MgSO
4powder (relative absolute dried paper pulp quality), after stirring, puts into supercritical CO
2in extraction kettle, add methyl alcohol as entrainer, methanol usage is 2% (relative absolute dried paper pulp quality).Extracting pressure is 10MPa, temperature 70 C, CO
2flow velocity is 16L/h, and the time is 60min.After separation, the paper pulp in extraction kettle being diluted to mass concentration through water washing is 12%, obtains just bleached pulp.Pulp density being concentrated into mass concentration is 7%, carry out ClO 2 bleaching, aqueous solution of chlorine dioxide concentration is 6g/L, and consumption is 0.3% (with the percentage of absolute dried paper pulp quality), original ph 6.0, temperature 40 DEG C, time is 30min, and drift pH is 4.0 eventually, finally washes dereaction residue with water, reach 6.5 to eluate pH value, obtain bleached pulp.
Result: supercritical CO
2after extraction just drift, paper pulp delignification rate is 63.7%; After ClO 2 bleaching, pulp brightness is 81.4%ISO.
Embodiment 3:
The raw material of this instance processes is rice straw pulp.Choose rice straw pulp 300g, in baking oven, carry out drying, baking temperature is 60 DEG C, makes paper pulp moisture be 7.5%.Dried paper pulp grinds, and gets the paper pulp that granule size is 330 μm, adds 0.4%MgSO
4powder (relative absolute dried paper pulp quality), after stirring, puts into supercritical CO
2in extraction kettle, add methyl alcohol as entrainer, methanol usage 3% (relative absolute dried paper pulp quality).Extracting pressure is 7MPa, temperature 90 DEG C, CO
2flow velocity is 20L/h, and the time is 90min.After separation, the paper pulp in extraction kettle being diluted to mass concentration through water washing is 13%, obtains just bleached pulp.Pulp density being concentrated into mass concentration is 10%, carry out ClO 2 bleaching, aqueous solution of chlorine dioxide concentration is 10g/L, and consumption is 1.2% (with the percentage of absolute dried paper pulp quality), original ph 5.0, temperature 70 C, time is 70min, and drift pH is 5 eventually, finally washes dereaction residue with water, reach 7 to eluate pH value, obtain bleached pulp.
Result: supercritical CO
2after extraction just drift, paper pulp delignification rate is 67.8%; After ClO 2 bleaching, pulp brightness is 85.3%ISO.
Claims (4)
1. a dioxde pulp bleaching process, is characterized in that, the method adopts supercritical carbon dioxide and chlorine dioxide united bleaching paper pulp, and concrete operation step is as follows:
(1) supercritical CO is adopted
2extraction: after the paper pulp crushing of drying is ground, add cellulose protective agent, powder is mixed rear threading supercritical CO
2in extraction kettle, and add entrainer extraction, supercritical CO
2extraction conditions: extraction temperature is 70-110 DEG C, extracting pressure is 7-15MPa, and extraction time is 60-120min, CO
2flow velocity is 16-25L/h, and after extraction, the paper pulp in extraction kettle being diluted to mass concentration through water washing is 12-15%;
(2) ClO 2 bleaching is adopted: be 7-12% by pulp concentrating to mass concentration, initial ph value scope is 4-6, temperature controls at 40-90 DEG C, and then the disposable aqueous solution of chlorine dioxide that adds is bleached, and the mass concentration of aqueous solution of chlorine dioxide is 6-15g/L, consumption is the 0.3%-1.8% of oven dry stock quality, bleaching time is 30-100min, and endpoint pH scope is 3-5, washes dereaction residue with water, reach 6-7 to eluate pH value, obtain bleached pulp;
In step (1), described paper pulp is with wheat straw or straw or bamboo pulp be raw material chemical pulp or reducing rules, and the drying process of paper pulp is: in baking oven, carry out drying, oven temperature is at 50-70 DEG C, and paper pulp moisture is after drying lower than 8%;
In step (1), described cellulose protective agent is MgSO
4, MgSO
4consumption is the 0.3-0.5% of oven dry stock quality.
2. dioxde pulp bleaching process according to claim 1, is characterized in that, in step (1), after described paper pulp crushing, size of powder particles is at 200-450 μm.
3. dioxde pulp bleaching process according to claim 1, is characterized in that, in step (1), described entrainer is methyl alcohol, and the consumption of methyl alcohol is the 2%-5% of oven dry stock quality.
4. dioxde pulp bleaching process according to claim 1, is characterized in that, in step (2), the preferable temperature of ClO 2 bleaching is 70 DEG C.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1033664A (en) * | 1987-09-08 | 1989-07-05 | 加拿大液态空气有限公司 | Method of manufcturing paper pulp |
| CN1955346A (en) * | 2005-10-24 | 2007-05-02 | 中国农业科学院麻类研究所 | Method for extracting ramie from supercritical CO2 media by enzyme method |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU2003208216A1 (en) * | 2002-03-06 | 2003-09-16 | Iogen Bio-Products Corporation | Xylanase treatment of chemical pulp |
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2014
- 2014-06-23 CN CN201410283889.9A patent/CN104032611B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1033664A (en) * | 1987-09-08 | 1989-07-05 | 加拿大液态空气有限公司 | Method of manufcturing paper pulp |
| CN1955346A (en) * | 2005-10-24 | 2007-05-02 | 中国农业科学院麻类研究所 | Method for extracting ramie from supercritical CO2 media by enzyme method |
Non-Patent Citations (3)
| Title |
|---|
| 张学俊 等.超临界流体萃取原理用于制浆研究.《中国造纸学报》.1995,第10卷第77～85页. * |
| 牦牛毛超临界CO2漂白研究;闫俊 等;《毛纺科技》;20110430;第39卷(第4期);第26～28页 * |
| 超临界流体技术在造纸工业中的应用;周秀风 等;《湖南造纸》;20071231(第1期);第19～20，25页 * |
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