EP0165867A1 - Process for bleaching mechanical pulp with hydrogen peroxide - Google Patents
Process for bleaching mechanical pulp with hydrogen peroxide Download PDFInfo
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- EP0165867A1 EP0165867A1 EP85401182A EP85401182A EP0165867A1 EP 0165867 A1 EP0165867 A1 EP 0165867A1 EP 85401182 A EP85401182 A EP 85401182A EP 85401182 A EP85401182 A EP 85401182A EP 0165867 A1 EP0165867 A1 EP 0165867A1
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- Prior art keywords
- oxygen
- hydrogen peroxide
- bleaching
- mechanical pulp
- treatment
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/16—Bleaching ; Apparatus therefor with per compounds
- D21C9/163—Bleaching ; Apparatus therefor with per compounds with peroxides
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/1057—Multistage, with compounds cited in more than one sub-group D21C9/10, D21C9/12, D21C9/16
Definitions
- the invention relates to a process for bleaching mechanical pulp with hydrogen peroxide.
- the bleaching of a mechanical paper pulp consists in eliminating the colored groups from the pulp by oxidation or by reduction of these groups, without dissolving the constituents of the wood in the bleaching liquor. This operation is carried out industrially with hydrogen peroxide H 2 O 2 (P) or hydrosulfite of sodium or zinc.
- the use of hydrogen peroxide (P) makes it possible to reach whiteness levels greater than those obtained with hydrosulfite. It has therefore become widespread, where the objective is to prepare whiteness 80 pasta (ISO standard).
- the bleaching is carried out either in a single stage with hydrogen peroxide, or in two stages, the first stage being a treatment with hydrogen peroxide and the second a treatment with hydrosulfite.
- the medium is made alkaline by the addition of caustic soda.
- the hydrogen peroxide rapidly decomposes into oxygen with transient formation of radical species ineffective in the bleaching process. This decomposition is catalyzed by the cations of transition metals present in the pulp.
- bleaching chemical pulps consists in dissolving the residual lignin (delignification), in order to obtain cellulosic pulps free of lignin. It is therefore no longer a question of carrying out a moderate treatment on the colored groups of the paste, but of depolymerizing and dissolving the macromolecules carrying these colored groups.
- oxygen is not a bleaching agent for mechanical pulps.
- DH ANDREWS and RP SINGH indicate in the work entitled “The bleaching of pulp", editor TAPPI Press (1979), page 215, that oxygen in an alkaline medium causes yellowing of the mechanical pulp, which is consistent with what is known about the chemistry of lignin in the presence of oxygen.
- oxygen is capable of enhancing the whitening action of hydrogen peroxide in the bleaching of mechanical pulps, whether the two reagents are used in sequence or simultaneously.
- the process for bleaching mechanical pulp with hydrogen peroxide according to the invention is characterized in that, before or simultaneously to said peroxide treatment, the mechanical pulp is subjected to an oxygen pressure.
- oxygen pressure is meant both the use of oxygen at atmospheric pressure and under pressure, the latter possibly reaching a few bars.
- the action of oxygen can therefore be exerted, either from atmospheric oxygen which then acts on the dough, in particular by sweeping or licking, or from oxygen under pressure, for example that exerted under the effect of the height of a column of dough in an ascending bleaching tower.
- oxygen can be used as a bleaching agent since, as we saw in the preamble, oxygen used alone in an alkaline medium has no bleaching action on a mechanical pulp.
- the mechanical pulp is bleached with hydrogen peroxide under the usual industrial conditions, that is to say in an alkaline medium in the presence of stabilizing agents which can be sodium silicate, magnesium sulfate, the complexing agents usually used, such as the sodium salts of diethylenetriaminopentacetic acid, at a temperature below 100 ° C. under an oxygen atmosphere.
- stabilizing agents which can be sodium silicate, magnesium sulfate, the complexing agents usually used, such as the sodium salts of diethylenetriaminopentacetic acid, at a temperature below 100 ° C. under an oxygen atmosphere.
- the mechanical pulp containing the bleaching agents can be mixed with gaseous oxygen in a suitable mixer before being sent to the bleaching tower, preferably upward.
- the pulp containing bleaching products is sent to a tower containing oxygen or to any other type of reactor containing oxygen and where the bleaching of the pulp will take place or will continue. It is therefore a process which will be called P / 0 (sequence: hydrogen peroxide / oxygen) according to the usual internationally accepted codification.
- the mechanical pulp made alkaline by addition of sodium hydroxide or silicate is mixed with oxygen, then left under oxygen pressure at a temperature below 100 ° C for the necessary time, which should not exceed four hours.
- This operation is carried out in a suitable reactor which can be a tower.
- the actual bleaching reagents are then added, in particular hydrogen peroxide.
- the dough is placed under the usual bleaching conditions with hydrogen peroxide. This process will therefore be referenced 0 P according to the accepted codification.
- the paste and the alkaline liquor are introduced into an enclosure at the processing temperature. After this treatment, the dough is washed. Its whiteness is 72.2%. The consumption of hydrogen peroxide is 1.75%.
- This test 1 corresponds to the sequence P.
- test No. 2 the same unbleached mechanical pulp is treated with oxygen under the following conditions:
- This test No. 2 therefore corresponds to the OP sequence.
- test 6 The same test is then repeated, this time subjecting the paste to an oxygen pressure of 2 bars throughout the treatment with hydrogen peroxide (test 6). After this P / O treatment, the whiteness obtained is 75.2%, a gain of 1.2 points compared to test no. 5 which does not include oxygen.
- the reference (1) designates the dough which is sent to the mixer (2) where it simultaneously receives oxygen (3) and hydrogen peroxide (4) brought into the mixer (2) by the valve three ways (5).
- the pasty mixture produced is sent through line (6) to arrive at the rising tower (7) where this mixture of paste and reagents remains for the time necessary for the reaction.
- the bleached pulp is recovered in (8).
- the height of the dough column in the tower (7) ensures sufficient oxygen pressure.
- the method according to the invention can be used successfully for bleaching mechanical pulps.
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Abstract
Description
L'invention concerne un procédé de blanchiment de pâte mécanique par le peroxyde d'hydrogène.The invention relates to a process for bleaching mechanical pulp with hydrogen peroxide.
Le blanchiment d'une pâte papetière mécanique consiste à éliminer les groupements colores de la pâte par oxydation ou par réduction de ces groupements, sans solubiliser les constituants du bois dans la liqueur de blanchiment. Cette opération est réalisée industriellement par le peroxyde d'hydrogène H2O2 (P) ou l'hydrosulfite de sodium ou de zinc.The bleaching of a mechanical paper pulp consists in eliminating the colored groups from the pulp by oxidation or by reduction of these groups, without dissolving the constituents of the wood in the bleaching liquor. This operation is carried out industrially with hydrogen peroxide H 2 O 2 (P) or hydrosulfite of sodium or zinc.
L'utilisation du peroxyde d'hydrogène (P) permet d'atteindre des niveaux de blancheur supérieure à ceux obtenus avec l'hydrosulfite. Elle s'est donc généralisée, là où l'objectif est de préparer des pâtes de blancheur 80 (norme ISO). Dans ce cas, le blanchiment est réalisé, soit en un seul stade avec du peroxyde d'hydrogène, soit en deux stades, le premier stade étant un traitement au peroxyde d'hydrogène et le second un traitement à l'hydrosulfite. Dans les conditions optimales d'utilisation du peroxyde d'hydrogène, le milieu est rendu alcalin par addition de soude caustique. Dans ce milieu, le peroxyde d'hydrogène se décompose rapidement en oxygène avec formation transitoire d'espèces radicalaires inopérantes dans le processus de blanchiment. Cette décomposition est catalysée par les cations des métaux de transition présents dans la pâte. Il en résulte une perte en peroxyde d'hydrogène, présent dans ce milieu sous la forme de l'anion HOO-, et donc une diminution de l'efficacité du blanchiment. Dans la pratique, la solution alcaline de peroxyde d'hydrogène est stabilisée par addition de silicate de sodium, de sel de magnésium et souvent de sequestrants des cations métalliques. Malgré ces précautions, la décomposition du peroxyde n'est pas totalement supprimée et l'on estime à 10 % environ la quantité de peroxyde ainsi perdue.The use of hydrogen peroxide (P) makes it possible to reach whiteness levels greater than those obtained with hydrosulfite. It has therefore become widespread, where the objective is to prepare whiteness 80 pasta (ISO standard). In this case, the bleaching is carried out either in a single stage with hydrogen peroxide, or in two stages, the first stage being a treatment with hydrogen peroxide and the second a treatment with hydrosulfite. Under the optimal conditions for using hydrogen peroxide, the medium is made alkaline by the addition of caustic soda. In this medium, the hydrogen peroxide rapidly decomposes into oxygen with transient formation of radical species ineffective in the bleaching process. This decomposition is catalyzed by the cations of transition metals present in the pulp. This results in a loss of hydrogen peroxide, present in this medium in the form of the HOO - anion, and therefore a decrease in the efficiency of bleaching. In practice, the alkaline solution of hydrogen peroxide is stabilized by the addition of sodium silicate, magnesium salt and often sequestrants of metal cations. Despite these precautions, the decomposition of the peroxide is not completely suppressed and the amount of peroxide thus lost is estimated at around 10%.
On a également proposé d'utiliser l'oxygène en tant qu'agent de blanchiment des pâtes chimiques. Contrairement au blanchiment des pâtes mécaniques, le blanchiment des pâtes chimiques consiste à dissoudre la lignine résiduelle (délignification), afin d'obtenir des pâtes cellulosiques exemptes de lignine. Il ne s'agit donc plus d'effectuer un traitement modéré sur les groupements colorés de la pâte, mais de dépolymériser et de dissoudre les macromolécules portant ces groupements colorés.It has also been proposed to use oxygen as a chemical pulp bleaching agent. Unlike bleaching mechanical pulps, bleaching chemical pulps consists in dissolving the residual lignin (delignification), in order to obtain cellulosic pulps free of lignin. It is therefore no longer a question of carrying out a moderate treatment on the colored groups of the paste, but of depolymerizing and dissolving the macromolecules carrying these colored groups.
On a aussi suggéré d'utiliser l'oxygène carme agent de cuisson de certaines plantes annuelles. Dans cette application, l'oxygène sert à dissoudre la lignine du végétal dans le but d'obtenir une pâte chimique.It has also been suggested to use the Carmine oxygen cooking agent of certain annual plants. In this application, oxygen is used to dissolve the lignin from the plant in order to obtain a chemical paste.
En revanche, l'oxygène n'est pas un agent de blanchiment des pâtes mécaniques. D'ailleurs, D.H. ANDREWS et R.P. SINGH indiquent dans l'ouvrage intitulé "The bleaching of pulp", éditeur TAPPI Press (1979), page 215, que l'oxygène en milieu alcalin provoque un jaunissement de la pâte mécanique, ce qui est conforme à ce que l'on sait de la chimie de la lignine en présence d'oxygène.However, oxygen is not a bleaching agent for mechanical pulps. Moreover, DH ANDREWS and RP SINGH indicate in the work entitled "The bleaching of pulp", editor TAPPI Press (1979), page 215, that oxygen in an alkaline medium causes yellowing of the mechanical pulp, which is consistent with what is known about the chemistry of lignin in the presence of oxygen.
Il a été démontré qu'au cours du traitement des végétaux ou des pâtes chimiques par l'oxygène, la dissolution de la lignine s'accompagnait de la formation de petites quantités de peroxyde d'hydrogène. On ne sait pratiquement rien de la participation du peroxyde d'hydrogène ainsi formé dans le mécanisme du blanchiment à l'oxygène des pâtes chimiques. Sans doute a-t-il lui aussi une action propre dans le blanchiment de la pâte chimique ainsi traitée. C'est la raison pour laquelle il a été proposé dans les procédés de délignification à l'oxygène, qu'il s'agisse de la cuisson des végétaux ou du blanchiment des pâtes chimiques, d'introduire du peroxyde d'hydrogène dans la liqueur. L'efficacité de la délignification s'en trouve améliorée. Il ressort donc de ces travaux que le peroxyde d'hydrogène peut renforcer l'action délignifiante de l'oxygène.It has been shown that during the treatment of plants or chemical pulps with oxygen, the dissolution of lignin is accompanied by the formation of small amounts of hydrogen peroxide. Virtually nothing is known about the participation of the hydrogen peroxide thus formed in the mechanism of oxygen bleaching of chemical pulps. No doubt it also has its own action in the bleaching of the chemical pulp thus treated. This is the reason why it has been proposed in oxygen delignification processes, whether it is cooking plants or bleaching chemical pulps, to introduce hydrogen peroxide into the liquor . The efficiency of delignification is improved. It is therefore clear from these works that hydrogen peroxide can reinforce the delignifying action of oxygen.
Contrairement à l'enseignement de l'art antérieur exposé ci-dessus, l'oxygène est capable de renforcer l'action blanchissante du peroxyde d'hydrogène dans le blanchiment des pâtes mécaniques, que les deux réactifs soient utilisés en séquence ou simultanément.Contrary to the teaching of the prior art set out above, oxygen is capable of enhancing the whitening action of hydrogen peroxide in the bleaching of mechanical pulps, whether the two reagents are used in sequence or simultaneously.
Le procédé de blanchiment de pâte mécanique par le peroxyde d'hydrogène conforme à l'invention se caractérise en ce que, préalablement ou simultanément audit traitement peroxyde, la pâte mécanique est soumise à une pression d'oxygène.The process for bleaching mechanical pulp with hydrogen peroxide according to the invention is characterized in that, before or simultaneously to said peroxide treatment, the mechanical pulp is subjected to an oxygen pressure.
Dans la suite du texte, par "pression d'oxygène", on entend aussi bien l'utilisation de l'oxygène à pression atmosphérique que sous pression, celle-ci pouvant atteindre quelques bars. L'action de l'oxygène peut donc s'exercer, soit à partir d'oxygène atmosphérique qui alors agit sur la pâte, notamment par balayage ou lèchage, soit à partir d'oxygène sous pression, par exemple celle exercée sous l'effet de la hauteur d'une colonne de pâte dans une tour ascendante de blanchiment.In the remainder of the text, by “oxygen pressure” is meant both the use of oxygen at atmospheric pressure and under pressure, the latter possibly reaching a few bars. The action of oxygen can therefore be exerted, either from atmospheric oxygen which then acts on the dough, in particular by sweeping or licking, or from oxygen under pressure, for example that exerted under the effect of the height of a column of dough in an ascending bleaching tower.
Il est tout à fait inattendu que l'oxygène puisse être utilisé comme agent de blanchiment puisque, comme on l'a vu dans le préambule, l'oxygène utilisé seul en milieu alcalin n'a aucune action blanchissante sur une pâte mécanique.It is completely unexpected that oxygen can be used as a bleaching agent since, as we saw in the preamble, oxygen used alone in an alkaline medium has no bleaching action on a mechanical pulp.
Dans une première forme de réalisation de l'invention, on réalise le blanchiment de la pâte mécanique par un peroxyde d'hydrogène dans les conditions industrielles habituelles, c'est-à-dire en milieu alcalin en présence d'agents stabilisants qui peuvent être le silicate de sodium, le sulfate de magnésium, les complexants habituellement utilisés comme les sels de sodium de l'acide diéthylenetriaminopentacétique, à température inférieure à 100°C sous atmosphère d'oxygène. Dans cette forme de réalisation, la pâte mécanique contenant les agents de blanchiment peut être mélangée avec de l'oxygène gazeux dans un mélangeur approprié avant d'être envoyé dans la tour de blanchiment, ascendante de préférence.In a first embodiment of the invention, the mechanical pulp is bleached with hydrogen peroxide under the usual industrial conditions, that is to say in an alkaline medium in the presence of stabilizing agents which can be sodium silicate, magnesium sulfate, the complexing agents usually used, such as the sodium salts of diethylenetriaminopentacetic acid, at a temperature below 100 ° C. under an oxygen atmosphere. In this embodiment, the mechanical pulp containing the bleaching agents can be mixed with gaseous oxygen in a suitable mixer before being sent to the bleaching tower, preferably upward.
Dans, une variante, la pâte contenant des produits de blanchiment est envoyée dans une tour contenant de l'oxygène ou dans tout autre type de réacteur contenant de l'oxygène et où se déroulera ou se poursuivra le blanchiment de la pâte. Il s'agit donc d'un procédé qui sera dénommé P/0 (séquence : peroxyde d'hydrogène/oxygène) selon la codification usuelle internationalement admise.In a variant, the pulp containing bleaching products is sent to a tower containing oxygen or to any other type of reactor containing oxygen and where the bleaching of the pulp will take place or will continue. It is therefore a process which will be called P / 0 (sequence: hydrogen peroxide / oxygen) according to the usual internationally accepted codification.
Dans une deuxième forme de réalisation, la pâte mécanique rendue alcaline par addition de soude ou de silicate, est mélangée avec de l'oxygène, puis laissée ainsi sous pression d'oxygène à une température inférieure à 100°C pendant le temps nécessaire, qui ne devrait pas excéder quatre heures. Cette opération s'effectue dans un réacteur approprié qui peut être une tour. On additionne ensuite les réactifs du blanchiment proprement dit, notamment le peroxyde d'hydrogène. Enfin, on place la pâte dans les conditions habituelles de blanchiment au peroxyde d'hydrogène. Ce procédé sera donc référencé 0 P selon la codification admise.In a second embodiment, the mechanical pulp made alkaline by addition of sodium hydroxide or silicate, is mixed with oxygen, then left under oxygen pressure at a temperature below 100 ° C for the necessary time, which should not exceed four hours. This operation is carried out in a suitable reactor which can be a tower. The actual bleaching reagents are then added, in particular hydrogen peroxide. Finally, the dough is placed under the usual bleaching conditions with hydrogen peroxide. This process will therefore be referenced 0 P according to the accepted codification.
D'autres combinaisons sont envisageables, par exemple la combinaison O P/0 dans lequel le deuxième stade de traitement est réalisé également sous atmosphère d'oxygène.Other combinations are possible, for example the O P / 0 combination in which the second stage of treatment is also carried out under an oxygen atmosphere.
Il va de soi qu'il peut être également utile d'effectuer dans le procédé selon l'invention des stades de lavage et/ou de pressage et de réaliser des recyclages partiels d'effluents contenant du peroxyde résiduel ou des produits d'oxydation de la pâte par l'oxygène ou le peroxyde d'hydrogène.It goes without saying that it may also be useful to carry out in the process according to the invention washing and / or pressing stages and to carry out partial recycling of effluents containing residual peroxide or oxidation products of the paste by oxygen or hydrogen peroxide.
Avantageusement, en pratique :
- - l'oxygène est utilisé, soit à pression atmosphérique, soit sous pression gazeuse;
- - la pression d'oxygène est inférieure à cinq bars et est notamment comprise entre deux et trois bars, ce qui permet d'utiliser des appareillages usuels; le procédé ne fait donc pas appel à un investissement coûteux;
- - lorsque la pression d'oxygène est appliquée, le pH de la pâte est compris entre neuf et douze, et de préférence entre dix et onze, c'est-à-dire entre les chiffres usuellement appliqués pour le blanchirent des pâtes mécaniques;
- - de même, lorsque cette pression d'oxygène est appliquée, la température est comprise entre 40 et 100°C, et de préférence 50 à 60°C; en effet, si la température excède 100°C, l'oxygène risque de délignifier la pâte;
- - la consistance de la pâte est comprise entre 8 et 30 %, et de préférence entre 10 et 20 %;
- - enfin, la liqueur de blanchiment au peroxyde d'hydrogène est une liqueur conventionnelle comprenant outre le peroxyde d'hydrogène, du silicate de sodium, et autres agents séquestrants habituellement utilisés.
- - oxygen is used, either at atmospheric pressure or under gas pressure;
- - The oxygen pressure is less than five bars and is in particular between two and three bars, which makes it possible to use conventional equipment; the process therefore does not require an expensive investment;
- - When the oxygen pressure is applied, the pH of the pulp is between nine and twelve, and preferably between ten and eleven, that is to say between the figures usually applied for the bleaching of mechanical pulps;
- - similarly, when this oxygen pressure is applied, the temperature is between 40 and 100 ° C, and preferably 50 to 60 ° C; indeed, if the temperature exceeds 100 ° C, oxygen risks delignifying the dough;
- - The consistency of the dough is between 8 and 30%, and preferably between 10 and 20%;
- - Finally, the bleaching liquor with hydrogen peroxide is a conventional liquor comprising, in addition to hydrogen peroxide, sodium silicate, and other sequestering agents usually used.
La manière dont l'invention peut être réalisée et les avantages qui en découlent ressortiront mieux des exemples de réalisation qui suivent donnés à titre indicatif et non limitatif.The manner in which the invention can be implemented and the advantages which ensue therefrom will emerge more clearly from the exemplary embodiments which follow, given by way of indication and without limitation.
Dans ces exemples, à l'exception de l'exemple 4,chaque fois, on soumet l'échantillon de la pâte à deux essais, à savoir :
- - le premier essai (
essais - - puis ensuite, à un traitement selon l'invention (essais 2, 4, 6), c'est-à-dire (P/0 ou OP).
- - the first test (
tests - - then thereafter, to a treatment according to the invention (tests 2, 4, 6), that is to say (P / 0 or OP).
Dans tous ces exemples, on utilise une pâte mécanique de meule de sapin épicéa ayant une blancheur écrue de 56 % mesurée selon la norme ISO sur l'appareil Elrepho.In all these examples, a mechanical pulp of spruce fir grindstone having an unbleached whiteness of 56% measured according to the ISO standard on the Elrepho apparatus is used.
Dans ce premier essai (essai n° 1), la pâte est blanchie en un seul stade par une liqueur alcaline de peroxyde d'hydrogène dans les conditions suivantes (les taux de réactif étant exprimés en poids de produit pur par rapport au poids de pâte compté en sec) :
Pour ce faire, la pâte et la liqueur alcaline sont introduites dans une enceinte à la température de traitement. Après ce traitement, la pâte est lavée. Son degré de blancheur est de 72,2 %. La consommation de peroxyde d'hydrogène est de l, 75 %.To do this, the paste and the alkaline liquor are introduced into an enclosure at the processing temperature. After this treatment, the dough is washed. Its whiteness is 72.2%. The consumption of hydrogen peroxide is 1.75%.
Cet essai 1 correspond à la séquence P.This
Dans un deuxième essai (essai n° 2), la même pâte mécanique écrue est traitée par l'oxygène dans les conditions suivantes :
Après ce traitement à l'oxygène (0), la pâte est lavée, puis est traitée par la liqueur contenant du peroxyde d'hydrogène (P) et ce, dans les mêmes conditions que dans l'essai 1. La blancheur obtenue est de 73,2 %. Cela représente un gain de 1 point par rapport à l'essai n°l. La consommation du peroxyde d'hydrogène est de 1, 5 %, soit inférieure de 0,25 % à celle du premier essai.After this oxygen treatment (0), the paste is washed, then it is treated with the liquor containing hydrogen peroxide (P) and this, under the same conditions as in
Cet essai n° 2 correspond donc à la séquence OP.This test No. 2 therefore corresponds to the OP sequence.
La même pâte que précédemment est traitée par la liqueur alcaline de peroxyde d'hydrogène de l'exemple 1 dans un autoclave métallique plongé dans le thermofluide d'un réacteur rotatif de laboratoire (essai n° 3). Les conditions de traitement sont identiques à celles de l'essai n° 1. Après cette séquence P, la blancheur obtenue est de 70,6 %, probablement du-fait d'un malaxage insuffisant.The same paste as above is treated with the alkaline hydrogen peroxide liquor of Example 1 in a metal autoclave immersed in the thermofluid of a laboratory laboratory reactor (test No. 3). The treatment conditions are identical to those of test No. 1. After this sequence P, the whiteness obtained is 70.6%, probably due to insufficient mixing.
On reprend le même essai en soumettant la pâte à une pression d'oxygène de 3 bars et ce, pendant tout le long du traitement par le peroxyde d'hydrogène (essai n° 4). La blancheur obtenue après ce traitement P/O, est de 72,3 %, soit un gain de 1,7 points par rapport à l'essai 3, dans lequel on n'a pas introduit d'oxygène.The same test is repeated by subjecting the paste to an oxygen pressure of 3 bars and this, throughout the treatment with hydrogen peroxide (test No. 4). The whiteness obtained after this P / O treatment is 72.3%, ie a gain of 1.7 points compared to
La même pâte mécanique de sapin épicéa que précédemment est traitée cette fois dans un réacteur horizontal agité intérieurement par des palettes fixées sur un arbre rotatif horizontal (essai 5) par la même liqueur alcaline de peroxyde d'hydrogène et ce, dans les conditions de l'essai n° 1. Après traitement (P), la blancheur est nettement améliorée puisqu'elle passe à 74 %.The same mechanical spruce fir pulp as before is treated this time in a horizontal reactor internally agitated by pallets fixed on a horizontal rotary shaft (test 5) with the same alkaline hydrogen peroxide liquor and this, under the conditions of l 'test n ° 1. After treatment (P), the whiteness is markedly improved since it drops to 74%.
On reprend ensuite le même essai en soumettant cette fois la pâte à une pression d'oxygène de 2 bars tout au long du traitement par le peroxyde d'hydrogène (essai 6). Après ce traitement P/O, la blancheur obtenue est de 75,2 %, soit un gain de 1,2 points par rapport à l'essai n° 5 qui ne comprend pas d'oxygène.The same test is then repeated, this time subjecting the paste to an oxygen pressure of 2 bars throughout the treatment with hydrogen peroxide (test 6). After this P / O treatment, the whiteness obtained is 75.2%, a gain of 1.2 points compared to test no. 5 which does not include oxygen.
La même pâte mécanique écrue de sapin épicéa, c'est-à-dire de blancheur 56 % est traitée par une liqueur alcaline sous une pression d'oxygène de 3 bars. Cette liqueur ne contient pas de peroxyde d'hydrogène. Les conditions de traitement sont identiques à celles de l'essai n° 4, c'est-à-dire avec utilisation d'un autoclave métallique. On soumet donc la pâte à une pression de 3 bars d'oxygène pendant toute la durée du traitement. Après ce traitement 0, la blancheur obtenue est de 54, 5 % contre 72,3 % selon l'invention.The same unbleached mechanical pulp of spruce fir, that is to say whiteness 56% is treated with an alkaline liquor under an oxygen pressure of 3 bars. This liquor does not contain hydrogen peroxide. The treatment conditions are identical to those of test No. 4, that is to say with the use of a metal autoclave. The dough is therefore subjected to a pressure of 3 bars of oxygen throughout the duration of the treatment. After this treatment 0, the whiteness obtained is 54.5% against 72.3% according to the invention.
Dans cet exenple, on traite, conformément au procédé selon l'invention, la même pâte mécanique de sapin épicéa que dans les autres exemples dans une tour montante schématisée à la figure unique annexée d'usage courant pour le blanchiment en papeterie.In this example, the same mechanical spruce fir pulp is treated, in accordance with the method according to the invention, as in the other examples in a rising tower shown diagrammatically in the attached single figure, commonly used for bleaching in stationery.
Dans cette figure, la référence (1) désigne la pâte qui est envoyée au mélangeur (2) où elle reçoit simultanément de l'oxygène (3) et du peroxyde d'hydrogène (4) amené dans le mélangeur (2) par la vanne trois voies (5).In this figure, the reference (1) designates the dough which is sent to the mixer (2) where it simultaneously receives oxygen (3) and hydrogen peroxide (4) brought into the mixer (2) by the valve three ways (5).
Le mélange pâteux réalisé est envoyé dans la conduite (6) pour arriver à la tour montante (7) où ce mélange pâte et réactifs séjourne le temps nécessaire pour la réaction. La pâte blanchie est récupérée en (8).The pasty mixture produced is sent through line (6) to arrive at the rising tower (7) where this mixture of paste and reagents remains for the time necessary for the reaction. The bleached pulp is recovered in (8).
La hauteur de la colonne de pâte dans la tour (7) assure une pression d'oxygène suffisante.The height of the dough column in the tower (7) ensures sufficient oxygen pressure.
Ces résultats montrent bien que dans le procédé selon l'invention, l'oxygène n'est pas en soi un agent de blanchiment de pâte mécanique (voir exemple 4), mais qu'en revanche, la combinaison de l'oxygène avec le peroxyde d'hydrogène agissant soit simultanément ou préalablement, renforce le pouvoir blanchissant du peroxyde d'hydrogêne.These results clearly show that in the process according to the invention, oxygen is not per se a mechanical pulp bleaching agent (see example 4), but that, on the other hand, the combination of oxygen with peroxide of hydrogen acting either simultaneously or beforehand, reinforces the whitening power of hydrogen peroxide.
De la sorte, le procédé selon l'invention peut être utilisé avec succès pour le blanchiment des pâtes mécaniques.In this way, the method according to the invention can be used successfully for bleaching mechanical pulps.
Claims (9)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT85401182T ATE31333T1 (en) | 1984-06-15 | 1985-06-14 | METHOD OF BLEACHING MECHANICAL PULP USING HYDROGEN PEROXIDE. |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8409718A FR2566015B1 (en) | 1984-06-15 | 1984-06-15 | PROCESS FOR BLEACHING MECHANICAL PASTE WITH HYDROGEN PEROXIDE |
| FR8409718 | 1984-06-15 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0165867A1 true EP0165867A1 (en) | 1985-12-27 |
| EP0165867B1 EP0165867B1 (en) | 1987-12-09 |
Family
ID=9305255
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP85401182A Expired EP0165867B1 (en) | 1984-06-15 | 1985-06-14 | Process for bleaching mechanical pulp with hydrogen peroxide |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US4756798A (en) |
| EP (1) | EP0165867B1 (en) |
| JP (1) | JP2504400B2 (en) |
| AT (1) | ATE31333T1 (en) |
| CA (1) | CA1259454A (en) |
| DE (1) | DE3561165D1 (en) |
| FR (1) | FR2566015B1 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0401149A1 (en) * | 1989-05-19 | 1990-12-05 | Fmc Corporation | Hydrogen peroxide reinforced oxygen delignification |
| EP0557651A1 (en) * | 1992-02-24 | 1993-09-01 | Scott Paper Company | Integrated pulping process of waste paper yielding tissue-grade paper fibers |
| US5698075A (en) * | 1991-03-11 | 1997-12-16 | Solvay Interox (Societe Anonyme) | Process for bleaching a chemical paper pulp in an oxygen-peroxymonosulfuric acid-hydrogen peroxide sequence |
| EP0816558A1 (en) * | 1996-06-29 | 1998-01-07 | Voith Sulzer Stoffaufbereitung GmbH | Process for increasing the degree of whiteness of paper making stock |
| CN108642943A (en) * | 2018-04-03 | 2018-10-12 | 中国林业科学研究院林产化学工业研究所 | A method of preparing high-whiteness high-strength Eucalyptus chemi-mechanical pulp |
Families Citing this family (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ES2004389A6 (en) * | 1986-03-21 | 1989-01-01 | Air Prod & Chem | Production of bleached pulp by oxygen/alkali extractant |
| SE466060C (en) | 1990-02-13 | 1995-09-11 | Moelnlycke Ab | Absorbent chemitermomechanical mass and preparation thereof |
| US5607546A (en) * | 1990-02-13 | 1997-03-04 | Molnlycke Ab | CTMP-process |
| NZ237019A (en) * | 1990-02-19 | 1992-11-25 | Amcor Ltd | Bleaching paper pulp by initially treating with oxygen and/or hydrogen peroxide and subsequently treating with a bleaching agent without intervening washing steps |
| AU642971B2 (en) * | 1990-02-19 | 1993-11-04 | Paper Australia Pty Ltd | Bleaching of paper pulp |
| US6149766A (en) * | 1993-06-08 | 2000-11-21 | Kvaerner Pulping Technologies, A/B | Process for peroxide bleaching of chemical pulp in a pressurized bleaching vessel |
| SE500616C2 (en) * | 1993-06-08 | 1994-07-25 | Kvaerner Pulping Tech | Bleaching of chemical pulp with peroxide at overpressure |
| CA2157154A1 (en) * | 1994-08-29 | 1996-03-01 | Gordon Leary | Bleaching of high-yield pulps with oxygen |
| BR9611974A (en) * | 1995-12-07 | 1999-11-03 | Beloit Technologies Inc | Oxygen delignification of medium pulp slurry. |
| GB0004988D0 (en) * | 2000-03-01 | 2000-04-19 | Unilever Plc | Composition and method for bleaching a substrate |
| US6627041B2 (en) * | 2000-03-06 | 2003-09-30 | Georgia-Pacific Corporation | Method of bleaching and providing papermaking fibers with durable curl |
| US6899790B2 (en) | 2000-03-06 | 2005-05-31 | Georgia-Pacific Corporation | Method of providing papermaking fibers with durable curl |
| US7297225B2 (en) * | 2004-06-22 | 2007-11-20 | Georgia-Pacific Consumer Products Lp | Process for high temperature peroxide bleaching of pulp with cool discharge |
| US8138106B2 (en) | 2005-09-30 | 2012-03-20 | Rayonier Trs Holdings Inc. | Cellulosic fibers with odor control characteristics |
| US20080087390A1 (en) * | 2006-10-11 | 2008-04-17 | Fort James Corporation | Multi-step pulp bleaching |
| US8845860B2 (en) | 2010-09-16 | 2014-09-30 | Georgia-Pacific Consumer Products Lp | High brightness pulps from lignin rich waste papers |
| TW201610261A (en) | 2014-05-20 | 2016-03-16 | 喬治亞太平洋消費者產品公司 | Bleaching and shive reduction process for non-wood fibers |
| TW201610265A (en) | 2014-05-20 | 2016-03-16 | 喬治亞太平洋消費者產品公司 | Bleaching and shive reduction process for non-wood fibers |
| TW201544652A (en) * | 2014-05-20 | 2015-12-01 | Georgia Pacific Consumer Prod | Bleaching and shive reduction process for non-wood fibers |
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- 1985-06-14 AT AT85401182T patent/ATE31333T1/en not_active IP Right Cessation
- 1985-06-14 EP EP85401182A patent/EP0165867B1/en not_active Expired
- 1985-06-14 CA CA000484053A patent/CA1259454A/en not_active Expired
- 1985-06-14 JP JP60128426A patent/JP2504400B2/en not_active Expired - Lifetime
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| DE2040763A1 (en) * | 1970-05-11 | 1971-11-18 | Kymin Oy Kymmene Ab | Two-stage bleaching of cellulose-containing materials |
| FR2301630A1 (en) * | 1975-02-24 | 1976-09-17 | Alf Sa | Paper pulp prodn. from wood or chips - by wetting with alkaline chemical prior to disintegration in pressure vessel supplied with compressed air |
| US4372812A (en) * | 1978-04-07 | 1983-02-08 | International Paper Company | Chlorine free process for bleaching lignocellulosic pulp |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0401149A1 (en) * | 1989-05-19 | 1990-12-05 | Fmc Corporation | Hydrogen peroxide reinforced oxygen delignification |
| US5698075A (en) * | 1991-03-11 | 1997-12-16 | Solvay Interox (Societe Anonyme) | Process for bleaching a chemical paper pulp in an oxygen-peroxymonosulfuric acid-hydrogen peroxide sequence |
| EP0557651A1 (en) * | 1992-02-24 | 1993-09-01 | Scott Paper Company | Integrated pulping process of waste paper yielding tissue-grade paper fibers |
| EP0816558A1 (en) * | 1996-06-29 | 1998-01-07 | Voith Sulzer Stoffaufbereitung GmbH | Process for increasing the degree of whiteness of paper making stock |
| CN108642943A (en) * | 2018-04-03 | 2018-10-12 | 中国林业科学研究院林产化学工业研究所 | A method of preparing high-whiteness high-strength Eucalyptus chemi-mechanical pulp |
| CN108642943B (en) * | 2018-04-03 | 2021-03-19 | 中国林业科学研究院林产化学工业研究所 | Method for preparing high-whiteness and high-strength eucalyptus chemi-mechanical pulp |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2504400B2 (en) | 1996-06-05 |
| EP0165867B1 (en) | 1987-12-09 |
| CA1259454A (en) | 1989-09-19 |
| FR2566015B1 (en) | 1986-08-29 |
| FR2566015A1 (en) | 1985-12-20 |
| DE3561165D1 (en) | 1988-01-21 |
| US4756798A (en) | 1988-07-12 |
| ATE31333T1 (en) | 1987-12-15 |
| JPS6112994A (en) | 1986-01-21 |
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