EP0222674A1 - Process for bleaching chemical wood pulps - Google Patents
Process for bleaching chemical wood pulps Download PDFInfo
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- EP0222674A1 EP0222674A1 EP86420266A EP86420266A EP0222674A1 EP 0222674 A1 EP0222674 A1 EP 0222674A1 EP 86420266 A EP86420266 A EP 86420266A EP 86420266 A EP86420266 A EP 86420266A EP 0222674 A1 EP0222674 A1 EP 0222674A1
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- Prior art keywords
- pulp
- weight
- alkaline extraction
- chlorine
- chlorine dioxide
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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
- D21C9/1026—Other features in bleaching processes
Definitions
- the present invention relates to a process for bleaching chemical pulp.
- the bleaching of chemical paper pulp that is to say unbleached cellulose pulp obtained by cooking lignocellulosic materials according to the so-called sulphite, sulphate or Kraft, soda or carbonate processes, is generally practiced in industry using chlorine or chlorine derivatives having, like chlorine, an oxidizing character, such as chlorine dioxide ClO2 or sodium hypochlorite NaOCl.
- None of these oxidizing agents is, however, capable of ensuring satisfactory whitening alone in a single operation. It is necessary to operate in several distinct stages and in intermediate operations such as in particular so-called alkaline bath extraction operations.
- a treatment with chlorine and chlorine dioxide in solution a first alkaline extraction with sodium hydroxide in solution
- a treatment with chlorine dioxide in solution a second alkaline extraction of the type of the first
- a second treatment with chlorine dioxide in solution it has been proposed to act either oxygen during the first alkaline extraction, i.e. hydrogen peroxide during the second alkaline extraction.
- the process of the invention has the advantage of achieving the aim aimed at on the two above plans without, moreover, affecting the quality of the bleached pulp finally obtained.
- the process of the invention is particularly suitable for bleaching chemical pulp from softwood.
- the amount of oxygen during the first alkaline extraction is generally between 0.2% and 1% by weight of the weight of dry pulp.
- the amount of hydrogen peroxide used during the second alkaline extraction is most often between 0.1% and 0.5% by weight of the weight of dry pulp.
- the treatment of the pulp with chlorine and chlorine dioxide in solution is carried out in known manner in a single bath, by means of an amount of total active chlorine in the form of chlorine and chlorine dioxide generally between 3% and 10% by weight of the weight of dry pulp, the amount of chlorine dioxide can advantageously represent from 10% to 70%, preferably up to 50% of the total active chlorine, at a temperature generally between 20 ° C and 50 ° C, for a period which may be between 5 minutes and 60 minutes, the action of chlorine dioxide acting simultaneously or, preferably, prior to that of chlorine and the pulp having a consistency most commonly understood between about 3% and 5%.
- the first alkaline extraction is carried out in the presence of oxygen as it usually is in the absence of this reagent, at a temperature of between approximately 50 ° C. and 80 ° C., for a period of time more often between 1 hour and 2 hours, by means of an amount of sodium hydroxide generally between 2% and 5% by weight of the weight of the dry dough, the consistency of the dough being most often between 10% and 15%.
- the treatment of the dough with chlorine dioxide which follows the first alkaline extraction, relates to a dough whose consistency is between about 10% and 15%, for about 1 hour to 4 hours at a temperature generally between 60 ° C and 90 ° C.
- the second alkaline extraction carried out in the presence of hydrogen peroxide, is carried out at a temperature generally between approximately 70 ° C. and 90 ° C. for approximately 0.5 hour to 2 hours, using a quantity sodium hydroxide generally representing from 0.5% to 2% by weight of the weight of dry dough, the consistency of the dough being most frequently between 10% and 15%.
- the treatment of the pulp with chlorine dioxide, which follows the second alkaline extraction, is carried out under conditions analogous to those described for the treatment with the same reagent which follows the first alkaline extraction.
- the quantity of chlorine dioxide generally employed in the two treatments of the pulp by means of this reagent which respectively follow the first and the second alkaline extraction depends on the conditions adopted according to the invention for the combined intervention of oxygen and hydrogen peroxide. It remains much lower, as is apparent from the examples which are given below, than that generally between 1% and 4% by weight of the weight of dry pulp, which is required, in the absence of the combined invention of the oxygen and hydrogen peroxide according to the invention, to achieve the same bleaching effect as that provided by proceeding according to the invention.
- the conditions of the process of the invention can advantageously be determined so that it does not exceed 1% and is even much less than 0.5% by weight of the weight of dry pulp.
- E1 alkaline extraction using sodium hydroxide solution.
- D1 treatment of the paste using chlorine dioxide, which follows the first alkaline extraction E1 or E1O as the case may be.
- D2 same meaning as D1, D2 coming after the second alkaline extraction E2 or E2 / P as the case may be.
- the amounts of reagents are expressed in percent by weight relative to the weight of dry paste, except in the case of particular indication.
- the state of the dough is defined by its degree of polymerization dp and by its whiteness expressed in ELREPHO degrees: ° ER as it is commonly measured by a person skilled in the art using an ELREPHO spectrophotometer from the company CARL ZEISS .
- the bleached pulp which ultimately results from this bleaching sequence has a whiteness of 90.1 ° ER.
- a whiteness close to 89 ° ER (88.4 ° ER) is found only when a quantity of ClO2 4 times greater in D1, 3 times greater in D2 is used by comparison with the process according to the invention.
- the process carried out as in the invention delivers a bleached pulp whose qualities, in particular of dp, are at least equal to those of the bleached pulps obtained by known methods, and this, although one might have feared the opposite.
- Example 1 By carrying out the process of the invention as described at the start of Example 1 up to D1, but, from D à, in a manner which differs from that of Example 1 in that the quantities of ClO2 involved in D1 and D2 are 0.1% and 0.4% respectively and in that the amount of hydrogen peroxide in E2 / P is no more than 0.1%, the index of whiteness of the pulp thus bleached still reaches nearly 88.5 ° ER.
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- Wood Science & Technology (AREA)
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Abstract
Description
La présente invention concerne un procédé de blanchiment de pâtes papetières chimiques.The present invention relates to a process for bleaching chemical pulp.
Le blanchiment des pâtes papetières chimiques, c'est-à-dire des pâtes de cellulose écrues obtenues par cuisson de matières ligno-cellulosiques selon les procédés dits au sulfite, au sulfate ou Kraft, à la soude ou au carbonate, est généralement pratiqué dans l'industrie à l'aide de chlore ou de dérivés chlorés ayant comme le chlore un caractère oxydant, tels que le bioxyde de chlore ClO₂ ou l'hypochlorite de sodium NaOCl.The bleaching of chemical paper pulp, that is to say unbleached cellulose pulp obtained by cooking lignocellulosic materials according to the so-called sulphite, sulphate or Kraft, soda or carbonate processes, is generally practiced in industry using chlorine or chlorine derivatives having, like chlorine, an oxidizing character, such as chlorine dioxide ClO₂ or sodium hypochlorite NaOCl.
Aucun de ces agents oxydants n'est toutefois capable d'assurer seul un blanchiment satisfaisant en une seule opération. Il est nécessaire d'opérer en plusieurs étapes distinctes et à des opérations intermédiaires telles qu'en particulier des opérations dites d'extraction en bain alcalin.None of these oxidizing agents is, however, capable of ensuring satisfactory whitening alone in a single operation. It is necessary to operate in several distinct stages and in intermediate operations such as in particular so-called alkaline bath extraction operations.
L'intervention d'agents oxydants non chlorés dans des séquences de blanchiment basées sur l'action d'agents chlorés a été proposée pour limiter la quantité de ceux-ci ordinairement engagée et les conséquences désavantageuses de leur emploi comme en particulier la délivrance d'effluents par trop fortement colorés, polluants et corrosifs.The intervention of non-chlorinated oxidizing agents in bleaching sequences based on the action of chlorinated agents has been proposed in order to limit the quantity of these ordinarily used and the disadvantageous consequences of their use such as in particular the delivery of effluents that are too strongly colored, polluting and corrosive.
C'est ainsi que, par exemple, dans une séquence de blanchiment incluant classiquement la suite d'étapes suivants : un traitement au moyen de chlore et de bioxyde de chlore en solution, une première extraction alcaline au moyen d'hydroxyde de sodium en solution, un traitement au moyen de bioxyde de chlore en solution, une deuxième extraction alcaline du type de la première, un second traitement au moyen de bioxyde de chlore en solution, il a été proposé de faire agir soit l'oxygène au cours de la première extraction alcaline, soit le peroxyde d'hydrogène au cours de la deuxième extraction alcaline.Thus, for example, in a bleaching sequence conventionally including the following sequence of steps: a treatment with chlorine and chlorine dioxide in solution, a first alkaline extraction with sodium hydroxide in solution , a treatment with chlorine dioxide in solution, a second alkaline extraction of the type of the first, a second treatment with chlorine dioxide in solution, it has been proposed to act either oxygen during the first alkaline extraction, i.e. hydrogen peroxide during the second alkaline extraction.
La mise en oeuvre de la sorte, l'un excluant l'autre, de l'oxygène d'une part, du peroxyde d'hydrogène d'autre part, permet, dans un cas comme dans l'autre, de réduire de manière pratiquement semblable la quantité d'agents de blanchiment chlorés normalement nécessaire à l'obtention d'un effet de blanchiment donné, mais encore très insuffisante sur le plan de l'économie du procédé comme sur celui de l'amoindrissement des inconvénients signalés plus haut.The implementation in this way, one excluding the other, oxygen on the one hand, hydrogen peroxide on the other hand, allows, in one case as in the other, to reduce so practically similar the quantity of chlorine-based bleaching agents normally necessary to obtain a given bleaching effect, but still very insufficient on the in terms of the economy of the process as in that of the lessening of the drawbacks mentioned above.
Le procédé de l'invention présente l'avantage d'atteindre le but visé sur les deux plans ci-dessus sans de plus porter la moindre atteinte à la qualité de la pâte blanchie finalement obtenue.The process of the invention has the advantage of achieving the aim aimed at on the two above plans without, moreover, affecting the quality of the bleached pulp finally obtained.
Il est caractérisé en ce que, dans une séquence de blanchiment d'une pâte papetière chimique incluant successivement un traitement de la pâte au moyen de chlore et de bioxyde de chlore en solution agissant en un seul bain, une première extraction alcaline au moyen d'hydroxyde de sodium en solution, un traitement de la pâte au moyen de bioxyde de chlore en solution, une deuxième extraction alcaline au moyen d'hydroxyde de sodium en solution et encore un traitement au moyen de bioxyde de chlore en solution, la pâte est soumise à la fois à l'action de l'oxygène au cours de la première extraction alcaline et à l'action du peroxyde d'hydrogène au cours de la deuxième extraction alcaline.It is characterized in that, in a bleaching sequence of a chemical paper pulp successively including a treatment of the pulp by means of chlorine and chlorine dioxide in solution acting in a single bath, a first alkaline extraction by means of sodium hydroxide solution, treatment of the dough with chlorine dioxide in solution, a second alkaline extraction with sodium hydroxide in solution and further treatment with chlorine dioxide in solution, the dough is subjected both to the action of oxygen during the first alkaline extraction and to the action of hydrogen peroxide during the second alkaline extraction.
Le procédé de l'invention convient spécialement bien pour le blanchiment des pâtes papetières chimiques de bois de résineux.The process of the invention is particularly suitable for bleaching chemical pulp from softwood.
La quantité d'oxygène au cours de la première extraction alcaline est généralement comprise entre 0,2% et 1% en poids du poids de pâte sèche.The amount of oxygen during the first alkaline extraction is generally between 0.2% and 1% by weight of the weight of dry pulp.
La quantité de peroxyde d'hydrogène mis en oeuvre au cours de la deuxième extraction alcaline est le plus souvent comprise entre 0,1 % et 0,5 % en poids du poids de pâte sèche.The amount of hydrogen peroxide used during the second alkaline extraction is most often between 0.1% and 0.5% by weight of the weight of dry pulp.
Le traitement de la pâte au moyen de chlore et de bioxyde de chlore en solution est effectué de manière connue eu un seul bain, au moyen d'une quantité de chlore actif total sous forme de chlore et de bioxyde de chlore comprise le plus souvent entre 3 % et 10 % en poids du poids de pâte sèche, la quantité de bioxyde de chlore pouvant avantageusement représenter de 10 % à 70 %, de préférence jusqu'à 50 % du chlore actif total, à une température en général comprise entre 20°C et 50 °C, pendant une durée pouvant être comprise entre 5 minutes et 60 minutes, l'action du bioxyde de chlore s'exerçant simultanément ou, de préférence, antérieurement à celle du chlore et la pâte ayant une consistance comprise le plus couramment entre environ 3 % et 5 %.The treatment of the pulp with chlorine and chlorine dioxide in solution is carried out in known manner in a single bath, by means of an amount of total active chlorine in the form of chlorine and chlorine dioxide generally between 3% and 10% by weight of the weight of dry pulp, the amount of chlorine dioxide can advantageously represent from 10% to 70%, preferably up to 50% of the total active chlorine, at a temperature generally between 20 ° C and 50 ° C, for a period which may be between 5 minutes and 60 minutes, the action of chlorine dioxide acting simultaneously or, preferably, prior to that of chlorine and the pulp having a consistency most commonly understood between about 3% and 5%.
La première extraction alcaline est réalisée en présence d'oxygène comme elle l'est d'habitude en l'absence de ce réactif, à une température comprise entre environ 50°C et 80°C, pendant une durée le plus souvent comprise entre 1 heure et 2 heures, au moyen d'une quantité d'hydroxyde de sodium généralement comprise entre 2 % et 5 % en poids du poids de la pâte sèche, la consistance de la pâte pouvant être comprise le plus souvent entre 10 % et 15 %.The first alkaline extraction is carried out in the presence of oxygen as it usually is in the absence of this reagent, at a temperature of between approximately 50 ° C. and 80 ° C., for a period of time more often between 1 hour and 2 hours, by means of an amount of sodium hydroxide generally between 2% and 5% by weight of the weight of the dry dough, the consistency of the dough being most often between 10% and 15%.
Le traitement de la pâte au moyen de bioxyde de chlore, qui suit la première extraction alcaline, porte sur une pâte dont la consistance est entre environ 10 % et 15 %, durant environ 1 heure à 4 heures à une température généralement comprise entre 60°C et 90°C.The treatment of the dough with chlorine dioxide, which follows the first alkaline extraction, relates to a dough whose consistency is between about 10% and 15%, for about 1 hour to 4 hours at a temperature generally between 60 ° C and 90 ° C.
La seconde extraction alcaline, pratiquée en présence du peroxyde d'hydrogène, est réalisée à une température comprise le plus souvent entre environ 70°C et 90°C durant environ 0,5 heure à 2 heures, à l'aide d'une quantité d'hydroxyde de sodium représentant généralement de 0,5 % à 2 % en poids du poids de pâte sèche, la consistance de la pâte étant le plus fréquemment comprise entre 10 % et 15 %.The second alkaline extraction, carried out in the presence of hydrogen peroxide, is carried out at a temperature generally between approximately 70 ° C. and 90 ° C. for approximately 0.5 hour to 2 hours, using a quantity sodium hydroxide generally representing from 0.5% to 2% by weight of the weight of dry dough, the consistency of the dough being most frequently between 10% and 15%.
Le traitement de la pâte par le bioxyde de chlore, qui suit la deuxième extraction alcaline, est effectué dans des conditions analogues à celles décrites pour le traitement au moyen du même réactif qui suit la première extraction alcaline.The treatment of the pulp with chlorine dioxide, which follows the second alkaline extraction, is carried out under conditions analogous to those described for the treatment with the same reagent which follows the first alkaline extraction.
La quantité de bioxyde de chlore globalement engagé dans les deux traitements de la pâte au moyen de ce réactif qui suivent respectivement la première et la deuxième extraction alcaline, dépend des conditions adoptées selon l'invention pour l'intervention combinée de l'oxygène et du peroxyde d'hydrogène. Elle reste très inférieure, comme il ressort des exemples qui sont donnés plus loin, à celle généralement comprise entre 1 % et 4 % en poids du poids de pâte sèche, qui est exigée, en l'absence de l'invention combinée de l'oxygène et du peroxyde d'hydrogène selon l'invention, pour atteindre le même effet de blanchiment que celui procuré en procédant selon l'invention.The quantity of chlorine dioxide generally employed in the two treatments of the pulp by means of this reagent which respectively follow the first and the second alkaline extraction, depends on the conditions adopted according to the invention for the combined intervention of oxygen and hydrogen peroxide. It remains much lower, as is apparent from the examples which are given below, than that generally between 1% and 4% by weight of the weight of dry pulp, which is required, in the absence of the combined invention of the oxygen and hydrogen peroxide according to the invention, to achieve the same bleaching effect as that provided by proceeding according to the invention.
Les conditions du procédé de l'invention peuvent être avantageusement déterminées pour qu'elle n'excède pas 1 % et soit même nettement inférieure à 0,5 % en poids du poids de pâte sèche.The conditions of the process of the invention can advantageously be determined so that it does not exceed 1% and is even much less than 0.5% by weight of the weight of dry pulp.
Les exemples ci-après, donnés à titre indicatif mais non limitatif illustrent l'invention ou sont fournis à titre comparatif.The examples below, given as an indication but not limiting, illustrate the invention or are provided for comparison.
Pour désigner les différentes étapes successives des séquences de blanchiment évoquées dans les exemples, les symboles suivants ont été adoptés :To designate the different successive stages of the bleaching sequences mentioned in the examples, the following symbols have been adopted:
C/D : traitment de la pâte au moyen du bioxyde de chlore et du chlore en un seul bain, l'action du bioxyde de chlore précédant celle du chlore.C / D: treatment of the pulp using chlorine dioxide and chlorine in a single bath, the action of chlorine dioxide preceding that of chlorine.
E₁ : extraction alcaline au moyen d'hydroxyde de sodium en solution.E₁: alkaline extraction using sodium hydroxide solution.
E₁/O : E₁ avec intervention de l'oxygène.E₁ / O: E₁ with oxygen intervention.
D₁ : traitement de la pâte au moyen du bioxyde de chlore, qui suit la première extraction alcaline E₁ ou E₁O suivant le cas.D₁: treatment of the paste using chlorine dioxide, which follows the first alkaline extraction E₁ or E₁O as the case may be.
E₂ : même signification que E₁.E₂: same meaning as E₁.
E₂/P : E₂ avec intervention du peroxyde d'hydrogène.E₂ / P: E₂ with the intervention of hydrogen peroxide.
D₂ : même signification que D₁, D₂ venant à la suite de la deuxième extraction alcaline E₂ ou E₂/P suivant le cas.D₂: same meaning as D₁, D₂ coming after the second alkaline extraction E₂ or E₂ / P as the case may be.
Dans tous les exemples les quantités de réactifs son exprimées en pour cent en poids par rapport au poids de pâte sèche, sauf en cas d'indication particulière.In all the examples, the amounts of reagents are expressed in percent by weight relative to the weight of dry paste, except in the case of particular indication.
L'état de la pâte est défini par son degré de polymérisation dp et par sa blancheur exprimée en degrés ELREPHO : °ER telle qu'elle est mesurée communément par l'homme du métier au moyen d'un spectrophotomètre ELREPHO de la Société CARL ZEISS.The state of the dough is defined by its degree of polymerization dp and by its whiteness expressed in ELREPHO degrees: ° ER as it is commonly measured by a person skilled in the art using an ELREPHO spectrophotometer from the company CARL ZEISS .
Une pâte chimique écrue qui résulte d'une cuisson KRAFT de bois de résineux, dont l'indice KAPPA par lequel est illustrée la teneur de la pâte en lignine est de 30 et dont la blancheur est mesurée comme correspondant à 26,6 °ER, est soumise à C/D dans les conditions suivantes :
L'extraction alcaline E₁/O qui suit est réalisée dans les conditions suivantes :
. NaOH : 3,9 %
. O₂ : 0,5 %
. température : 60°C, (la pression étant dans ce cas de 2 bars).
. durée : 1,5 heure
. pâte, consistance : 10 %
Puis D₁ est réalisé ainsi :
. ClO₂ : 0,3 %
. température : 70°C
. durée : 2,5 heures
. pâte, consistance : 10 %,
E₂/P comme suit :
. NaOH : 0,75 %
. H₂O₂ : 0,20 %
. température : 80°C
. durée : 1,5 heure
. pâte, consistance : 10 %
et enfin, D₂ de la façon ci-dessous :
. ClO₂ : 0,2 %
. température : 80°C
. durée : 2,5 heures
. pâte, consistance : 10 %The following alkaline extraction E₁ / O is carried out under the following conditions:
. NaOH: 3.9%
. WHERE: 0.5%
. temperature: 60 ° C, (the pressure in this case being 2 bars).
. duration: 1.5 hours
. dough, consistency: 10%
Then D₁ is carried out as follows:
. ClO₂: 0.3%
. temperature: 70 ° C
. duration: 2.5 hours
. dough, consistency: 10%,
E₂ / P as follows:
. NaOH: 0.75%
. H₂O₂: 0.20%
. temperature: 80 ° C
. duration: 1.5 hours
. dough, consistency: 10%
and finally, D₂ in the way below:
. ClO₂: 0.2%
. temperature: 80 ° C
. duration: 2.5 hours
. dough, consistency: 10%
La pâte blanchie qui résulte finalement de cette séquence de blanchiment a une blancheur de 90,1° ER.The bleached pulp which ultimately results from this bleaching sequence has a whiteness of 90.1 ° ER.
Dans un but de comparaison, il est fait en sorte que le procédé décrit ci-dessus ne comporte plus l'intervention de l'oxygène, ni celle du peroxyde d'hydrogène.For the purpose of comparison, it is ensured that the process described above no longer involves the intervention of oxygen, nor that of hydrogen peroxide.
Il n'est retrouvé une blancheur voisine de 89°ER (88,4°ER) que lorsque est engagée par comparaison au procédé selon l'invention, une quantité de ClO₂ 4 fois supérieure en D₁, 3 fois supérieure en D₂.A whiteness close to 89 ° ER (88.4 ° ER) is found only when a quantity of ClO₂ 4 times greater in D₁, 3 times greater in D₂ is used by comparison with the process according to the invention.
Toujours dans un but de comparaison, une blancheur de 89°ER ne peut être retrouvée, lorsque, par rapport au procédé de l'invention, il est omis de procéder à l'intervention soit de l'oxygène, soit du peroxyde, qu'à la condition de concéder une consommation en ClO₂ en D₁ et D₂ au moins 2 fois plus élevée qu'en procédant selon l'invention.Still for the purpose of comparison, a whiteness of 89 ° ER cannot be found, when, in relation to the process of the invention, it is omitted to carry out the intervention either of oxygen or of peroxide, that on the condition of conceding a consumption of ClO₂ in D₁ and D₂ at least 2 times higher than by proceeding according to the invention.
Enfin la mise en jeu des quantités de ClO₂ en D₁ et en D₂, respectivement, comme dans le procédé de l'invention, conduit malgré tout à une blancheur de la pâte obtenue fortement diminuée lorsque soit l'oxygène, soit le peroxyde d'hydrogène n'intervient plus d'une façon conjuguée avec l'autre comme dans l'invention.Finally, the bringing into play of the quantities of ClO₂ in D₁ and in D₂, respectively, as in the process of the invention, nevertheless leads to a whiteness of the paste obtained greatly reduced when either oxygen or hydrogen peroxide no longer intervenes in a combined manner with the other as in the invention.
Ainsi, en mettant en jeu en D₁ et D₂ les quantités de ClO₂ mentionnées dans le procédé de l'invention décrit au début de cet exemple, mais en supprimant l'intervention du peroxyde d'hydrogène, la blancheur de la pâte finalement obtenue n'est plus que de 84,9°ER.Thus, by bringing into play in D₁ and D₂ the amounts of ClO₂ mentioned in the process of the invention described at the beginning of this example, but by eliminating the intervention of hydrogen peroxide, the whiteness of the paste finally obtained does not is more than 84.9 ° ER.
Le procédé conduit comme dans l'invention délivre une pâte blanchie dont les qualités , en particulier de dp, sont au moins égales à celles des pâtes blanchies obtenues par les procédés connus, et ce, bien que l'on ait pu craindre le contraire.The process carried out as in the invention delivers a bleached pulp whose qualities, in particular of dp, are at least equal to those of the bleached pulps obtained by known methods, and this, although one might have feared the opposite.
En réalisant le procédé de l'invention comme il est décrit en début de l'exemple 1 jusqu'à D₁, mais, à partir de D₁, d'une manière qui diffère de celle de l'exemple 1 en ce que les quantités de ClO₂ mis en jeu en D₁ et D₂ sont de 0,1 % et 0,4 % respectivement et en ce que la quantité de peroxyde d'hydrogène en E₂/P n'est plus que de 0,1 %, l'indice de blancheur de la pâte ainsi blanchie atteint encore près de 88,5°ER.By carrying out the process of the invention as described at the start of Example 1 up to D₁, but, from D à, in a manner which differs from that of Example 1 in that the quantities of ClO₂ involved in D₁ and D₂ are 0.1% and 0.4% respectively and in that the amount of hydrogen peroxide in E₂ / P is no more than 0.1%, the index of whiteness of the pulp thus bleached still reaches nearly 88.5 ° ER.
Cet exemple illustre le fait que même en ne mettant en jeu qu'une très faible quantité de peroxyde d'hydrogène, l'effet multiplicateur des actions conjuguées selon l'invention de l'oxygène et du peroxyde d'hydrogène reste pleinement assuré.This example illustrates the fact that even by using only a very small amount of hydrogen peroxide, the multiplier effect of the combined actions according to the invention of oxygen and hydrogen peroxide remains fully ensured.
Claims (14)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT86420266T ATE48291T1 (en) | 1985-10-30 | 1986-10-28 | PROCESS FOR BLEACHING CHEMICAL WOOD PULP. |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8516332A FR2589494B1 (en) | 1985-10-30 | 1985-10-30 | PROCESS FOR BLEACHING CHEMICAL PAPER PULP |
| FR8516332 | 1985-10-30 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0222674A1 true EP0222674A1 (en) | 1987-05-20 |
| EP0222674B1 EP0222674B1 (en) | 1989-11-29 |
Family
ID=9324477
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP86420266A Expired EP0222674B1 (en) | 1985-10-30 | 1986-10-28 | Process for bleaching chemical wood pulps |
Country Status (11)
| Country | Link |
|---|---|
| EP (1) | EP0222674B1 (en) |
| JP (1) | JPS62141188A (en) |
| AT (1) | ATE48291T1 (en) |
| AU (1) | AU603556B2 (en) |
| DE (2) | DE3667184D1 (en) |
| ES (1) | ES2000019B3 (en) |
| FI (1) | FI85294B (en) |
| FR (1) | FR2589494B1 (en) |
| NO (1) | NO864319L (en) |
| PT (1) | PT83649B (en) |
| ZA (1) | ZA868275B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6569284B1 (en) * | 1996-09-24 | 2003-05-27 | International Paper Company | Elemental-chlorine-free bleaching process having an initial Eo or Eop stage |
| WO2018134525A1 (en) | 2017-01-23 | 2018-07-26 | Centre Technique De L'industrie Des Papiers, Cartons Et Celluloses | Method for bleaching paper pulp |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4031597A1 (en) * | 1990-10-05 | 1992-04-09 | Sueddeutsche Kalkstickstoff | METHOD FOR LOW-CHLORINE BLEACHING AND DELIGNIFICATION OF CELLULAR |
-
1985
- 1985-10-30 FR FR8516332A patent/FR2589494B1/en not_active Expired
-
1986
- 1986-10-28 ES ES86420266T patent/ES2000019B3/en not_active Expired - Lifetime
- 1986-10-28 EP EP86420266A patent/EP0222674B1/en not_active Expired
- 1986-10-28 AT AT86420266T patent/ATE48291T1/en not_active IP Right Cessation
- 1986-10-28 DE DE8686420266T patent/DE3667184D1/en not_active Revoked
- 1986-10-28 DE DE198686420266T patent/DE222674T1/en active Pending
- 1986-10-29 AU AU64492/86A patent/AU603556B2/en not_active Ceased
- 1986-10-29 NO NO864319A patent/NO864319L/en unknown
- 1986-10-29 PT PT83649A patent/PT83649B/en not_active IP Right Cessation
- 1986-10-29 FI FI864411A patent/FI85294B/en not_active Application Discontinuation
- 1986-10-30 ZA ZA868275A patent/ZA868275B/en unknown
- 1986-10-30 JP JP61259562A patent/JPS62141188A/en active Granted
Non-Patent Citations (4)
| Title |
|---|
| TAPPI JOURNAL, vol. 66, no. 8, août 1983, pages 77-80, Atlanta, Georgia, US; W.H.RAPSON et al.: "Peroxide or hypochlorite in the E2 stage of CEDED bleaching of kraft pulp : effect on shilves" * |
| TAPPI JOURNAL, Vol. 67, no. 3, mars 1984, pages 66-68; Atlanta, Georgia, US; S.NIELSEN: "Optimizing a southern kraft softwood bleach plant when design capacity is exceeded" * |
| TAPPI JOURNAL, vol. 67, no. 6, juin 1984, pages 54-57, Atlanta, Georgia, US; S.M.ENZ et al.: "Oxidative extraction: an opportunityfor splitting the bleach plant" * |
| TAPPI JOURNAL, vol. 69, no. 7, juillet 1986, pages 90-93, Atlanta, Georgia, US; D.LACHENAL et al.: "Reinforcement of Oxygen-Alkali Extraction with hydrogen peroxide or hypochlorite * |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6569284B1 (en) * | 1996-09-24 | 2003-05-27 | International Paper Company | Elemental-chlorine-free bleaching process having an initial Eo or Eop stage |
| WO2018134525A1 (en) | 2017-01-23 | 2018-07-26 | Centre Technique De L'industrie Des Papiers, Cartons Et Celluloses | Method for bleaching paper pulp |
| FR3062138A1 (en) * | 2017-01-23 | 2018-07-27 | Centre Technique De L'industrie Des Papiers, Cartons Et Celluloses | PROCESS FOR WHITENING A PAPER PULP |
| RU2747664C2 (en) * | 2017-01-23 | 2021-05-11 | Сантр Текник Де Л'Индустри Де Папье, Картон И Селлюлоз | Paper pulp bleaching method |
| US11384480B2 (en) | 2017-01-23 | 2022-07-12 | Centre Technique De L'industrie Des Papiers, Cartons Et Celluloses | Method for bleaching paper pulp |
Also Published As
| Publication number | Publication date |
|---|---|
| ATE48291T1 (en) | 1989-12-15 |
| DE3667184D1 (en) | 1990-01-04 |
| AU603556B2 (en) | 1990-11-22 |
| JPS62141188A (en) | 1987-06-24 |
| ZA868275B (en) | 1987-06-24 |
| EP0222674B1 (en) | 1989-11-29 |
| ES2000019A4 (en) | 1987-09-16 |
| FI85294B (en) | 1991-12-13 |
| JPH0116958B2 (en) | 1989-03-28 |
| FI864411A0 (en) | 1986-10-29 |
| DE222674T1 (en) | 1987-10-15 |
| PT83649A (en) | 1986-11-01 |
| FI864411A (en) | 1987-05-01 |
| FR2589494A1 (en) | 1987-05-07 |
| NO864319D0 (en) | 1986-10-29 |
| PT83649B (en) | 1989-05-31 |
| ES2000019B3 (en) | 1990-03-16 |
| FR2589494B1 (en) | 1988-07-29 |
| NO864319L (en) | 1987-05-04 |
| AU6449286A (en) | 1987-05-07 |
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