CN101463573B - Straw pulp bleaching technique - Google Patents
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- CN101463573B CN101463573B CN2008101438944A CN200810143894A CN101463573B CN 101463573 B CN101463573 B CN 101463573B CN 2008101438944 A CN2008101438944 A CN 2008101438944A CN 200810143894 A CN200810143894 A CN 200810143894A CN 101463573 B CN101463573 B CN 101463573B
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Abstract
The invention discloses a bleaching process with low pollution used for straw pulp by virtue of elemental chlorine-free bleaching agents such as oxygen, chlorine dioxide, hydrogen peroxide and the like. The invention is characterized in that the process comprises the steps as follows: (1) on oxygen delignification section, sealing, sifting and washing are carried out; (2) on chlorine dioxide delignification section, washing is carried out; (3) on alkaline extraction section, washing is carried out; (4) on chlorine dioxide whitening section, washing and papermaking are carried out. The processof the invention is simple and feasible, applicable for reed pulps and the mixed pulp thereof and anaphalis yedoensis, the final brightness of the pulp of the reed pulps (ISO) reaches 78-85%, the brightness stability and the strength are good, and tear index is more than or equal to 8.0mN.m<2>/g; as no elemental chlorine joins the bleaching process, the generation amount of organic chloride during the bleaching process is greatly lowered and the pollution to ecological environment is reduced, thus having obvious social and economic benefits.
Description
Technical field:
The present invention relates to and a kind of bleaching process of from straw pulp, removing lignin particularly a kind of straw pulp bleaching process that adopts element-free chlorine to float agent.
Background technology:
China is straw pulp big producing country, and straw pulp output accounts for the over half of world wide production.In China, the bleaching of straw pulp always is adopts hypochlorite (H) singing stage bleaching or hypochlorite (HH) to float or chlorination-alkali treatment-hypochlorite chlorine bleach technologies such as (CEH) for two sections.When adopting this technology bleaching, slurry floats and decreases greatly, retention of whiteness is poor, easy brightness reversion, particularly in the reaction of bleaching process based on substitution reaction, produce a large amount of organochlorines for thing (AOX), its Main Ingredients and Appearance is the chloro phenols, the toxicity that has is very big, wherein even also contain toxic very strong dioxin, these Toxics are very harmful to the mankind and ecological environment, and therefore a lot of countries have carried out strict restriction to the content in the bleaching effluent, China in " paper industry water pollutes the standard of putting " of promulgation in 2008 also with the AOX generation as one of controlling index.In order to alleviate of the harm of straw pulp bleaching effluent, just must reduce the growing amount of AOX in the straw pulp bleaching process to environment.Know that now the AOX growing amount in the bleaching process is relevant with the elemental chlorine consumption in the bleaching process, therefore in the bleaching straw pulp process, few with so that the agent of floating that need not contain elemental chlorine be only the effective way of dealing with problems.Be based on the recognition, China papermaker bleaches tradition and has done some improvement.As the patent No. is ZL 02135330.1, and Granted publication number is CN 1176269C, and denomination of invention is that the patent of invention of paper pulp bleaching process discloses a kind of two sections straw pulp bleaching process of HD of being made up of hypochlorite prebleaching and chlorine dioxide post-bleach; Another patent No. is ZL200510135862.6, Granted publication number is CN 100372996C, and denomination of invention is that the patent of invention of improved paper pulp bleaching process discloses a kind of three sections reed pulp bleaching process of OXH of being made up of oxygen delignification, biology enzyme bleaching and hypochlorite bleaching.These two kinds of bleaching process are owing to cancelled the chlorination section, compare traditional multistage bleaching technology, reduced the growing amount of AOX in the bleaching process, but owing to all kept the hypochlorite bleaching section, thereby in bleaching process, still have the elemental chlorine of a great deal of to participate in bleaching action, and can produce chloroform with carcinogenesis, and still contain certain toxicant in all these two kinds of bleaching process institute waste discharges, ecological environment is still had bigger harm.
Summary of the invention:
ClO
2It is a kind of good bleaching agent, have good delignification selectivity and good environmental effect, according to document announcement (scape China paper industry information: the cnpaperinfo.com chlorine dioxide is in the application in papermaking industry prospect), under identical effective chlorine consumption, the AOX growing amount of ClO 2 bleaching only is 1/5 of elemental chlorine bleaching, be 2/5 of hypochlorite bleaching, though and in the ClO 2 bleaching process, still have AOX to produce, find as yet that so far wherein toxic material exists.
The purpose of this invention is to provide and a kind ofly float the low pollution bleaching process that agent is applicable to straw pulp by means of element-free chlorine such as oxygen, chlorine dioxide, hydrogen peroxide, this technology is compared with HD and OXH bleaching process after traditional bleaching process, the improvement, the bleaching effluent environmental pollution is littler, and final products are more excellent.
The present invention adopts following technical scheme to realize its goal of the invention, a kind of straw pulp bleaching process, and it may further comprise the steps:
(1) oxygen delignification section, closed screening, washing; (2) chlorine dioxide delignification stages, washing; (3) alkali extracting processing section, washing; (4) the chlorine dioxide section of brightening, washing is sent and is copied paper.
The present invention is to through the later straw pulp of washing when carrying out oxygen delignification, for the hardness permanganate number that guarantees slurry is reduced to 6-8 from 10-12, and with the content of residual lignin in the maximum minimizing slurry, and the intensity of not obvious infringement fiber.Need in slurry, add enough oxygen, alkali, and suitable process conditions is provided.In step (1), the slurry reaction concentration of oxygen delignification (O) section is 8%-16%, and reaction temperature is 85 ℃-120 ℃, because the wash degree of starching has great influence to the oxygen delignification effect, so sodium hydroxide concentration is the 10kg/t-25kg/t slurry; Flow of oxygen is between the 15kg/t-40kg/t slurry, according to starching the clean level adjustment; The reaction tower top pressure is 200Kpa-500Kpa, and the reaction time is 40min-60min.Because the oxygen delignification section is to carry out at pressure condition, can add in the slurry in order to guarantee oxygen, need guarantee that oxygen pressure reaches 0.85MPa-1.5MPa.
The present invention is for removing the residual lignin in the slurry as much as possible, and improves the whiteness of slurry, bleaches processing with the slurry of chlorine dioxide after to oxygen delignification, in step (2), and chlorine dioxide delignification (D
0) section slurry reaction concentration be 8%-16%, because under higher pH value, chlorine dioxide can be hydrolyzed to chlorate and chlorite, causes the loss of ClO 2 bleaching potentiality, and under low pH value, five oxidation equivalents of chlorine dioxide can participate in bleaching, therefore be 2.5-4.5 in this section by adding inorganic acid adjustment terminal point pH value, reaction temperature is 30 ℃-75 ℃, and the reaction time is 40min-70min, the chlorine dioxide consumption depends on the permanganate number of slurry, D
0The chlorine dioxide consumption of section is generally the 8kg/t-20kg/t slurry, like this can be at D
0Section is removed the residual lignin in the slurry as much as possible.Through D
0Slurry after section is handled enters next section processing after washing, the whiteness (ISO) of reed reed pulp material can reach 55%-65% after washing.
The present invention increases the solubility of acidic materials for the acid lignin that neutralization still remains in the slurry reduces product, so that better it is washed out in the slurry washing process, to process D
0Slurry after section is handled and washed carries out the alkali extracting.In step (3), the slurry reaction concentration that (E) section is handled in the alkali extracting is 8%-16%, for obtaining extraction rate was acquired preferably, addition amount of sodium hydroxide is 10kg/t-15kg/t, terminal point PH is 10.5-12.5, and the reaction time is 80min-150min, and reaction temperature is 50 ℃-80 ℃.
The present invention can add a spot of oxygen in alkali extracting processing section process, constitute the extracting of oxygen boosting alkali, i.e. E
0Section, oxygen consuming amount are the 5kg/t-10kg/t slurry, and reaction pressure is 150KPa-300KPa.
The present invention also can add hydrogen peroxide and constitute the extracting of hydrogen peroxide reinforced alkaline, i.e. E
PSection, hydrogen peroxide is with being the 3kg/t-6kg/t slurry.
The present invention can also add oxygen simultaneously and hydrogen peroxide constitutes E
OPSection.Oxygen consuming amount is the 5kg/t-10kg/t slurry, and reaction pressure is 150KPa-300KPa, and the hydrogen peroxide consumption is the 3kg/t-6kg/t slurry.
In alkali extracting processing section, the adding of these oxidants is equivalent to can increase the dissolution rate of lignin at the additional oxidation panel of alkali extracting processing section, thereby has improved the effect that the alkali extracting is handled.Slurry after the alkali extracting processing is washed, dissolved lignin degradation products to remove.
The present invention is for brightening, and the slurry after with chlorine dioxide the alkali extracting being handled carries out post-bleach to be handled.In step (4), chlorine dioxide brightens (D
1) section reaction density be 8%-16%, D
1Section is also carried out under acid condition, with D
0Duan Butong, D
1In the section slurry lignin content still less, and treatment temperature is higher, the time is longer, for preventing the undue loss of pulp yield, pH value should compare D
0Section control is higher, and the terminal point pH value is controlled at 5.0-6.0, because slurry is at D
0Lignin content after the E section is very little, therefore at D
1Section is except that removing residual lignin; main is that the coloring matter reaction generates colourless substance in chlorine dioxide and the slurry; play the effect of brightening paper pulp; the reaction speed of this effect is very slow, and in order to reach desired value, reaction temperature is 40 ℃-75 ℃; reaction time is 120min-180min; this section main effect is to brighten, and therefore too high chlorine dioxide consumption can not bring whiteness correspondingly to improve, therefore at D
1Section chlorine dioxide consumption is the 1kg/t-6kg/t slurry.Reach 78%-85% through the pulp brightness (ISO) after this section processing and the washing.
The present invention is in step (1), the optimal reaction temperature of oxygen delignification section is 95 ℃-105 ℃, and sodium hydroxide concentration is the 14kg/t-16kg/t slurry, and flow of oxygen is the 30kg/t-35kg/t slurry, the reaction tower top pressure is 350Kpa-400Kpa, and the reaction time is 40min-60min.
The present invention is in step (3), and the addition amount of sodium hydroxide of alkali extracting processing section is 10kg/t-12kg/t, and terminal point PH is 11.0-11.5, and reaction temperature is 65 ℃-70 ℃.
Because adopt technique scheme, the present invention has realized goal of the invention preferably, its technology simple possible, be applicable to reed pulp, reed reed pulp and mixed pulp thereof, the final one-tenth pulp brightness (ISO) of reed reed pulp reaches 78%-85%, and retention of whiteness is good, intensity is good, tear index 〉=8.0mNm
2/ g owing to there is not elemental chlorine to participate in, makes that the organic chloride growing amount in the bleaching process declines to a great extent in bleaching process, alleviated the pollution to ecological environment, has remarkable social benefit and ecological benefits.
The specific embodiment:
The invention will be further described below in conjunction with embodiment.
Embodiment 1:
A kind of straw pulp bleaching process, it may further comprise the steps:
(1) oxygen delignification section, closed screening, washing; (2) chlorine dioxide delignification stages, washing; (3) alkali extracting processing section, washing; (4) the chlorine dioxide section of brightening, washing is sent and is copied paper.
The present invention is washing later straw pulp (straw pulp that present embodiment uses is the reed pulp that adopts the sulfate process continuously cooking to obtain) when carrying out oxygen delignification to process, for the hardness permanganate number that guarantees slurry is reduced to 6-8 from 10-12 (present embodiment is 10.5), with the content of residual lignin in the maximum minimizing slurry, and the intensity of unconspicuous infringement fiber.Need in slurry, add enough oxygen, alkali, and suitable process conditions is provided.In step (1), the slurry reaction concentration of oxygen delignification (O) section is 8%-16% (present embodiment is 10%), reaction temperature is 85 ℃-120 ℃, and (the best is 95 ℃-105 ℃, present embodiment is 100 ℃), because the wash degree of starching has great influence to the oxygen delignification effect, therefore sodium hydroxide concentration is 10kg/t-25kg/t slurry (the best 14kg/t-16kg/t of being, present embodiment is 15kg/t, promptly add 1.5% NaOH, naoh concentration is 400g/l), flow of oxygen is 15kg/t-40kg/t slurry (the best 30kg/t-35kg/t of being, present embodiment is 30kg/t), reaction pressure is 200Kpa-500Kpa (the best 350Kpa-400Kpa of being, present embodiment is 400Kpa), and the reaction time is 40min-60min (present embodiment is 60min).Because oxygen delignification (O) section is to carry out at pressure condition, can add in the slurry in order to guarantee oxygen, need guarantee that oxygen pressure reaches 0.85MPa-1.5MPa (present embodiment is 1.0MPa).Earlier through the vacuum pulp washing machine of two series connection, enter pulp storage tower through the slurry after the oxygen delignification section then, after slurry goes out pulp storage tower, enter a vacuum pulp washing machine again, make slurry washing clean, be sent to next section (D again
0Section) handles.
The present invention is for removing the residual lignin in the slurry as much as possible, and improves the whiteness of slurry, bleaches processing with the slurry of chlorine dioxide after to oxygen delignification, in step (2), and (D before the ClO 2 bleaching
0) the slurry reaction concentration of section is 8%-16% (present embodiment is 9% for adding water adjusting slurry concentration), because under higher pH value, chlorine dioxide can be hydrolyzed to chlorate and chlorite, cause the loss of ClO 2 bleaching potentiality, and under low pH value, five oxidation equivalents of chlorine dioxide can participate in bleaching, therefore adjust terminal point pH value 2.5-4.5 (it is 3.0 that present embodiment is regulated pH value for adding hydrochloric acid) in this section by adding inorganic acid, reaction temperature is 30 ℃-75 ℃ (present embodiment is 50 ℃), reaction time is 40min-70min (present embodiment is 60min), the chlorine dioxide consumption depends on the permanganate number of slurry, D
0Section is generally 8kg/t-20kg/t slurry (present embodiment is 14kg/t, promptly adds 1.4% chlorine dioxide, and chlorine dioxide concentration is 10g/l), like this can be at D
0Section is removed the residual lignin in the slurry as much as possible.Through D
0Slurry after section is handled is sent to next section (E section) then and handles through a vacuum pulp washing machine washes clean, and the whiteness of reed slurry (ISO) can reach 55%-65% (present embodiment is 60%) after washing.
The present invention increases the solubility of acidic materials for the acid lignin that neutralization still remains in the slurry reduces product, so that better it is washed out in the slurry washing process, to process D
0Slurry after section is handled and washed carries out the alkali extracting.In step (3), the slurry reaction concentration that (E) section is handled in the alkali extracting is 8%-16% (present embodiment is 11% for adding water adjusting slurry concentration), for obtaining extraction rate was acquired preferably, (the best is 10kg/t-12kg/t to add NaOH 10kg/t-15kg/t, present embodiment is 11kg/t), adjusting terminal point PH is 10.5-12.5 (the best 11.0-11.5 of being, present embodiment is 11.0), reaction time is 80min-150min (present embodiment is 90min), reaction temperature is 50 ℃-80 ℃ (the best is 65 ℃-70 ℃, and present embodiment is 65 ℃).
The present invention can add a spot of oxygen in alkali extracting processing section process, constitute the extracting of oxygen boosting alkali, i.e. E
0Section, oxygen consuming amount are the 5kg/t-10kg/t slurry, and reaction pressure is 150KPa-300KPa.
The present invention also can add hydrogen peroxide and constitute the extracting of hydrogen peroxide reinforced alkaline, i.e. E
PSection, hydrogen peroxide is with being the 3kg/t-6kg/t slurry.
The present invention can also add oxygen simultaneously and hydrogen peroxide constitutes E
OPSection.Oxygen consuming amount is the 5kg/t-10kg/t slurry, and reaction pressure is 150KPa-300KPa, and the hydrogen peroxide consumption is the 3kg/t-6kg/t slurry.
Present embodiment is selected to add hydrogen peroxide and is constituted the extracting of hydrogen peroxide reinforced alkaline, i.e. E
PSection, hydrogen peroxide consumption are the 5kg/t slurry.
In alkali extracting processing section, the adding of these oxidants is equivalent to can increase the dissolution rate of lignin at the additional oxidation panel of alkali extracting processing section, thereby has improved the effect that the alkali extracting is handled.Slurry after the alkali extracting processing through a vacuum pulp washing machine washes clean, is dissolved lignin degradation products to remove, be sent to next section (D then
1Section) handles.
The present invention is for brightening, and the slurry after with chlorine dioxide the alkali extracting being handled carries out post-bleach to be handled.In step (4), chlorine dioxide brightens (D
1) reaction density of section is 8%-16% (present embodiment is 10% for adding water adjusting slurry concentration), D
1Section is also carried out under acid condition, with D
0Duan Butong, D
1In the section slurry lignin content still less, and treatment temperature is higher, the time is longer, for preventing the undue loss of pulp yield, pH value should compare D
0Section control is higher, and the terminal point pH value is controlled at 5.0-6.0 (present embodiment is 5.5 for adding hydrochloric acid adjusting pH value), because slurry is at D
0Lignin content after the E section is very little, therefore at D
1Section is except that removing residual lignin; main is that the coloring matter reaction generates colourless substance in chlorine dioxide and the slurry; play the effect of brightening paper pulp; the reaction speed of this effect is very slow, and in order to reach desired value, reaction temperature is 40 ℃-75 ℃ (present embodiment is 70 ℃); reaction time is 120min-180min (present embodiment is 160min); this section main effect is to brighten, and therefore too high chlorine dioxide consumption can not bring whiteness correspondingly to improve, therefore at D
1Section chlorine dioxide consumption is controlled to be 1kg/t-6kg/t slurry (present embodiment is 2kg/t, promptly adds 0.2% chlorine dioxide, and chlorine dioxide concentration is 10g/l).Slurry is through a vacuum pulp washing machine washes clean, and this clean slurry is sent to machine room.Can reach 78%-85% (present embodiment is 81.2%) through the pulp brightness (ISO) after this section processing and the washing.
The whiteness of present embodiment gained finished product slurry is 81.2%, and weight in wet base is 3.3g, and beating degree is 27 ° of SR, and tensile strength is 2.0kN/m, tear index 9.5mNm
2/ g.
Embodiment 2:
The slurry that present embodiment uses is the reed pulp that adopts the sulfate process continuously cooking to obtain, and permanganate number is 9.5.
In the oxygen delignification section: the reaction density of slurry is 9.5%, and reaction temperature is 95 ℃, and the addition of NaOH is 12kg/t, and flow of oxygen is 25kg/t, handles 55min under the condition of reaction pressure 350Kpa.
In the chlorine dioxide delignification stages: the chlorine dioxide addition is 12kg/t, and reaction density is 9.5%, terminal point pH value 3.0, and reaction temperature is 52 ℃, reaction time 65min.
At alkaline extraction section: slurry reaction concentration is 10%, and reaction temperature is 70 ℃, and the hydrogen peroxide addition is 4.0kg/t, and it is 10.5 that reaction time 100min, hydro-oxidation sodium make reaction end PH, and slurry enters bleaching section after washing.
In the chlorine dioxide section of brightening: the chlorine dioxide consumption is 1.5kg/t, and reaction density is 9.5%, terminal point pH value 5.0, and reaction temperature is 70 ℃, reaction time 150min, after reaction finishes, filtering stock.
Surplus with embodiment 1.
After testing, the whiteness of present embodiment gained finished product slurry is 82.1%, and weight in wet base is 2.9g, and beating degree is 29 ° of SR, and tensile strength is 1.9kN/m, and tear index is 10.2mNm
2/ g.Slurry viscosity is 1119, bleaching aqueous amount 25m
3/ ton slurry, the COD growing amount is 32kg/ ton slurry, the AOX growing amount is 0.6kg/ ton slurry.
Bleaching process of the present invention has following characteristics:
1, in the situation that guarantees pulp strength, carry out oxygen delignification, delignification rate can reach more than 30%, thereby reduces the load of following bleaching, reduces the consumption of following bleaching chemicals.
2, the waste water of oxygen delignification section can all be delivered to black wash and wash riddler's section, send at last between the alkali recovery vehicle and processes, and greatly reduces the pollutional load of discharge of wastewater, water saving 50%-70%.
3, fully phased out chlorination section and hypochlorite bleaching section, thereby the AOX growing amount in the bleaching process descends significantly, wastewater toxicity obviously reduces, and the organochlorine in the bleaching effluent can reduce more than 60% for the amount of thing, and is littler to the pollution of environment.
4, optionally oxidation lignin and pigment of ClO 2 bleaching is little to the degraded of carbohydrate, thereby the gained pulp strength is good, the whiteness height, and good stability, whiteness improves 3%ISO-4%ISO, and tear index improves more than 60%.
Compare with the HD bleaching process, whiteness improves more than 7%, and tear index improves more than 1 times, and viscosity improves more than 24%, and water saving is more than 50%, and the COD growing amount reduces more than 40%, and the AOX growing amount reduces more than 70%.
Compare with the OXH bleaching process, tear index improves more than 90%, and viscosity improves more than 20%, and the AOX growing amount reduces more than 20%.
Claims (9)
1. straw pulp bleaching process is characterized in that it may further comprise the steps:
(1) oxygen delignification section, closed screening, washing; The slurry reaction concentration of oxygen delignification section is 8%-16%, reaction temperature is 85 ℃-120 ℃, and sodium hydroxide concentration is the 10-25kg/t slurry, and flow of oxygen is the 15-40kg/t slurry, the reaction tower top pressure is 200kPa-500kPa, and the reaction time is 40min-60min; (2) chlorine dioxide delignification stages, washing; (3) alkali extracting processing section, washing; (4) the chlorine dioxide section of brightening, washing is sent and is copied paper.
2. a kind of straw pulp bleaching process according to claim 1, it is characterized in that in step (2), the slurry reaction concentration of chlorine dioxide delignification stages is 8%-16%, the chlorine dioxide consumption is the 8-20kg/t slurry, reaction temperature is 30 ℃-75 ℃, reaction time is 40min-70min, endpoint pH 2.5-4.5.
3. a kind of straw pulp bleaching process according to claim 1, it is characterized in that in step (3), the slurry reaction concentration of alkali extracting processing section is 8%-16%, addition amount of sodium hydroxide is the 10-15kg/t slurry, terminal point pH is 10.5-12.5, reaction time is 80min-150min, and reaction temperature is 50 ℃-80 ℃.
4. a kind of straw pulp bleaching process according to claim 3 is characterized in that in step (3), and alkali extracting processing section adopts oxygen boosting, and oxygen consuming amount is the 5-10kg/t slurry, and reaction pressure is 150kPa-300kPa.
5. a kind of straw pulp bleaching process according to claim 3 is characterized in that in step (3), and alkali extracting processing section adopts hydrogen peroxide to strengthen, and the hydrogen peroxide consumption is the 3-6kg/t slurry.
6. a kind of straw pulp bleaching process according to claim 3, it is characterized in that in step (3) alkali extracting processing section adopts oxygen and hydrogen peroxide to strengthen simultaneously, oxygen consuming amount is the 5-10kg/t slurry, reaction pressure is 150kPa-300kPa, and the hydrogen peroxide consumption is the 3-6kg/t slurry.
7. a kind of straw pulp bleaching process according to claim 1, it is characterized in that in step (4), the slurry reaction concentration of the chlorine dioxide section of brightening is 8%-16%, reaction temperature is 40 ℃-75 ℃, reaction time is 120min-180min, the chlorine dioxide consumption is the 1-6kg/t slurry, endpoint pH 5.0-6.0.
8. a kind of straw pulp bleaching process according to claim 1, it is characterized in that in step (1), the reaction temperature of oxygen delignification section is 95 ℃-105 ℃, sodium hydroxide concentration is the 14-16kg/t slurry, flow of oxygen is the 30-35kg/t slurry, the reaction tower top pressure is 350kPa-400kPa, and the reaction time is 40min-60min.
9. a kind of straw pulp bleaching process according to claim 1 is characterized in that in step (3), and the addition amount of sodium hydroxide of alkali extracting processing section is the 10-12kg/t slurry, and terminal point pH is 11.0-11.5, and reaction temperature is 65 ℃-70 ℃.
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| CN2008101438944A CN101463573B (en) | 2008-12-08 | 2008-12-08 | Straw pulp bleaching technique |
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| CN2008101438944A CN101463573B (en) | 2008-12-08 | 2008-12-08 | Straw pulp bleaching technique |
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Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102086604A (en) * | 2010-11-30 | 2011-06-08 | 陕西科技大学 | Method for bleaching alkaline wheat straw pulp with medium-concentration DEP (diethyl phthalate) |
| CN102182093B (en) * | 2011-03-31 | 2012-08-22 | 重庆理文造纸有限公司 | Bleaching process of bamboo dissolving pulp |
| CN102352572B (en) * | 2011-09-30 | 2013-07-24 | 重庆理文造纸有限公司 | Preparation method for bamboo wood dissolving pulp |
| CN102493260A (en) * | 2011-11-29 | 2012-06-13 | 沅江纸业有限责任公司 | Mixed paper pulp of reed and poplar as well as its production method |
| CN102493258A (en) * | 2011-11-30 | 2012-06-13 | 沅江纸业有限责任公司 | Woodfree writing paper and production method thereof |
| CN102877347B (en) * | 2012-09-18 | 2015-05-13 | 恒天海龙股份有限公司 | Bleaching technology for using chemical paper pulp to prepare dissolving pulp |
| CN102888775B (en) * | 2012-11-07 | 2015-03-04 | 河南科技学院 | Bleaching process of paper pulp |
| CN104074087B (en) * | 2014-06-30 | 2016-04-20 | 四川理工学院 | A kind of employing OD 1epD 2technique makes the method for Eupatorium adenophorum bleached pulp |
| CN105040500A (en) * | 2015-09-06 | 2015-11-11 | 长沙理工大学 | Elemental chlorine free bleaching method of reed pulp |
| CN113550167A (en) * | 2021-07-29 | 2021-10-26 | 陕西科技大学 | Elemental chlorine-free bleaching method for straw pulp |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1101860A1 (en) * | 1999-11-19 | 2001-05-23 | Praxair Technology, Inc. | Method for bleaching pulp with activated ozone |
| CN101082187A (en) * | 2007-08-03 | 2007-12-05 | 山东泉林纸业有限责任公司 | Oxygen delignify treating method for grass group unbleached chemical pulp |
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2008
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1101860A1 (en) * | 1999-11-19 | 2001-05-23 | Praxair Technology, Inc. | Method for bleaching pulp with activated ozone |
| CN101082187A (en) * | 2007-08-03 | 2007-12-05 | 山东泉林纸业有限责任公司 | Oxygen delignify treating method for grass group unbleached chemical pulp |
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