WO1996009434A1 - Procede de blanchiment de pate kraft - Google Patents

Procede de blanchiment de pate kraft Download PDF

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Publication number
WO1996009434A1
WO1996009434A1 PCT/FI1995/000506 FI9500506W WO9609434A1 WO 1996009434 A1 WO1996009434 A1 WO 1996009434A1 FI 9500506 W FI9500506 W FI 9500506W WO 9609434 A1 WO9609434 A1 WO 9609434A1
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WO
WIPO (PCT)
Prior art keywords
stage
pulp
peroxide
bleaching
signifies
Prior art date
Application number
PCT/FI1995/000506
Other languages
English (en)
Inventor
Kaj Henricson
Olavi Pikka
Original Assignee
Ahlstrom Machinery Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ahlstrom Machinery Oy filed Critical Ahlstrom Machinery Oy
Priority to CA002200327A priority Critical patent/CA2200327C/fr
Publication of WO1996009434A1 publication Critical patent/WO1996009434A1/fr
Priority to FI971023A priority patent/FI971023A/fi
Priority to SE9700992A priority patent/SE9700992L/xx

Links

Classifications

    • 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
    • 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
    • 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
    • D21C9/147—Bleaching ; Apparatus therefor with oxygen or its allotropic modifications
    • 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

Definitions

  • the present invention relates to a method of bleaching sulfate pulp, i.e. so-called kraft pulp, to a brightness of at least ISO 85 by using elemental chlorine free chemicals such as, for instance, oxygen and peroxide.
  • Ozone has its drawbacks. The most significant of these is perhaps the high price which is mostly due to the fairly difficult production method. A further drawback is its high reactivity which means that bleaching equipment using ozone, as well as the ones using gaseous chlorine, must be kept absolutely gas tight. For the same reason, ozone easily damages cellulose itself if the dose of ozone is not exactly correct or if adequate mixing is not provided.
  • the present invention pays attention to the environment protection values which direct the development away from the use of chlorine chemicals, and to economic aspects which at least to some extent speak against the use of ozone.
  • bleaching sequences utilizing peroxide have included as an essential part thereof a so-called Q stage which removes metals and precedes each peroxide stage and is separated by an efficient intermediate washing stage from the peroxide stage. This has been considered necessary also when the sequence has included several P stages.
  • the Q stage may involve mere acidification of the pulp at a low pH (pH approx. 3 - 5) or treatment with a complex former such as EDTA or DTPA at a pH of 4 - 6.
  • a complex former such as EDTA or DTPA
  • the method of the invention has made it possible to bleach pulp to a brightness of 85 - 88 ISO, and even greater, without the use of chlorine and also without the use of ozone if such is considered a risk.
  • a characteristic feature of the present invention is that pulp is at least partially bleached with peroxide alone, or with peroxide and oxygen, at acidic conditions.
  • This kind of an acidic peroxide method has been suggested for example in Finnish patent application no. 906076 and some older articles.
  • both the patent application mentioned above and the articles deal with bleaching of sulfite pulp with peroxide at acidic conditions.
  • one of the most significant differences between the sulfate and the sulfite processes is the acidity of the cook; a sulfate cook is alkaline and a sulfite cook acidic.
  • the pH of the cook is acidic, heavy metals are efficiently separated to the digestion liquid and most of them are removed during brown stock washing prior to bleaching. In sulfate digestion, heavy metals are not separated into the digestion liquid and thus cannot be removed in the brown stock washing.
  • Figs. 1 - 5 illustrate a few bleaching sequences according to preferred embodiments of the invention
  • Fig. 6 illustrates graphically the brightness and Kappa numbers obtained by a sequence according to the invention as compared with two other potential sequences.
  • Fig. l illustrates a bleaching sequence 0-Q-(OP)m-P a Q-P, preceded by a sulfate digestion either in a continuous or a so-called batch digester to a Kappa number of 30 - 15, preferably to a Kappa number of approx. 20. It is possible to reach even lower Kappa numbers by some advanced digestion methods but in most cases that happens at the expense of the yield.
  • the 0 stage at the beginning of the sequence is a so-called oxygen delignification stage which aims at bringing the Kappa number down to below 15, preferably below 12.
  • the oxygen delignification is followed by a Q stage already described above employed to remove heavy metals from the cellulose pulp by chelating (with EDTA, DTPA or corresponding chelating agents) where metal ions are combined chemically into complexes or by acidifying where metal ions dissolve in the liquid phase so that heavy metals do not cause problems in the following peroxide (P) stage.
  • P peroxide
  • a Q stage performed as an acid stage lowers the Kappa number whereby this phenomenon can be taken in use when delignifying of pulp is wanted, and especially in combination with oxygen stages.
  • the Q stage is preferably carried out at a pH range of 3 - 6 and at a temperature of 60 - 100°C and with a treatment time of 20 - 120 min.
  • a so-called DD washer manufactured by A. Ahlstrom Corporation and disclosed for example in U.S. patents no. 4,919,158 and 5,116,423, is used as the washing device.
  • the advantage provided by this kind of a fractionating washer is the washing result which is remarkably more efficient and precise than the one obtained by a conventional washer, and the production of filtrate fractions having different concentrations, the utilization of which filtrate fractions gives other advantages to the process.
  • the subsequent oxygen stage (OP)m in fact comprises one or several, preferably pressurized, oxygen and/or peroxide stages with no intermediate washing between them as is closer described in Finnish patent application no. 934056.
  • oxygen and/or peroxide stage having one step or several steps, oxygen or peroxide may be added as supplemental chemical to one step or several steps if desired.
  • one-step oxygen and/or peroxide stage also for example the following two-step stages may be used: 0/0, 0/P, P/O, P/P, OP/0, PO/O, OP/P, PO/P, OP/OP, OP/PO, P0/P0, and PO/OP in which the first character in each step stands for the main active bleaching chemical and the possible second character for the supporting bleaching chemical.
  • the substantially delignifying part of the sequence may, for instance, be O - Q - 0, O - Q - OP, 0 - Q - P, O - Q - O/O, 0 - Q - 0/P, 0 - Q - P/0, O - Q - P/P etc.
  • the Kappa number of the pulp has reduced to the range of 8 - 3.
  • the oxygen and/or peroxide stage is followed in the sequence by a peroxide stage connected to the process directly after the washer of the oxygen stage without a metal removal preceding a P stage.
  • the solution allowing operation without a separate metal removal stage (Q) by acidifying or chelating prior to a peroxide stage is reducing the pH of the peroxide stage acidic to a range of 2 - 6, preferably to 4 - 6. It is also preferable that the acidic peroxide stage P a is pressurized (the pressure being usually below 10 bar, preferably 3 - 5 bar) and that the temperature is 60 - 130°C, preferably 90
  • Activators may be added to a peroxide stage of this kind to disperse hydrogen peroxide so as to produce a strong oxidant.
  • the peroxide may be dissolved to water and active oxygen. Pressurizing the stage ensures that the produced gaseous chemical stays close to the fiber.
  • An acidic peroxide stage P a may be combined with a Q stage during which for example EDTA or acid is added to the pulp to remove heavy metals.
  • Both steps in the P a Q stage, or quite as well in a QP a stage, are performed at a pH of below 7, at the same temperature, preferably within the range mentioned above, in both the steps, and preferably with at least the P a step being pressurized, which also was described above.
  • the pH may be adjusted between the steps if the pH of the P a step is very low, i.e. below 3.
  • the pH of the Q step should be 3
  • the last treatment stage in the sequence described here is an alkaline peroxide stage employed to increase the final brightness to a desired level, preferably over 88.
  • the process conditions in this P stage are: the pH 10 - 12, the temperature 60 - 130°C, preferably 90 - 110°C, the pressure usually below 10 bar, preferably 3 - 5 bar, and the treatment time 30 - 120 min.
  • Fig. 2 illustrates an embodiment slightly different from the sequence in Fig. 1.
  • the single- or multi-step oxygen/peroxide stage (OP)m now stands for a multi-step oxygen stage intensified with peroxide (OP/OP) .
  • Fig. 3 illustrates an alternative sequence in which the first step of a multi-step oxygen/peroxide stage has been intensified with peroxide (OP/P) .
  • Fig. 4 illustrates the one-step oxygen/peroxide stage of Fig. 1 as a multi-step peroxide stage (P/P) .
  • Fig. 5 illustrates an embodiment in which the multi-step peroxide stage of Fig. 4 has been replaced by a multi- step peroxide stage and in which the first peroxide step has been intensified with oxygen (PO/P) .
  • Figure 6 illustrates results received from comparative laboratory tests performed. The figure illustrates the changes in Kappa number and brightness obtained from tests using three sequences. In addition to comparison of different potential bleaching sequences, the objective of the test was also to find out, by stabilizing the total peroxide volume used in the whole sequence to six per cent irrespective of the number of peroxide stages or steps, which sequence would give the best bleaching result.
  • the sequences used in the tests were Q - PO/P - P, Q - PO/P - P a Q - PO and for comparison a sequence Q - PO/P - Z - P containing ozone.
  • Yet another interesting and especially promising bleaching method includes a novel pretreat ent with an oxygen delignification stage followed by a Q stage run as an acid stage (A) and an oxygen bleaching stage.
  • the property of an acid stage to decrease the Kappa number of pulp is used.
  • the acid stage (A) in accordance with this embodiment is different from the Q stage discussed earlier as in A stage the main concern is not to remove heavy metals but to improve bleachability by lowering the lignin content of pulp.
  • the pulp production begins with the following partial sequence digestion - O - A - 0.
  • the following practical example describes the process in more detail.
  • pulp having a full brightness was produced with only two peroxide stages in addition to the pretreatment of the present invention, i.e. the entire sequence being digestion - 0 - A - O - P a Q - P.
  • Another sequence producing corresponding brightness values i.e. digestion - O - A - O - ZQ - P, used only one P stage but an ozone stage was needed.
  • the use of a sequence digestion - O - A - O - DQ - P comes into question which would drastically reduce the use of chlorine dioxide.
  • the final bleaching stage P may be preceded by P a Q, ZQ, DQ or any other oxidative treatment combined with a Q stage.

Landscapes

  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
  • Paper (AREA)

Abstract

L'invention concerne un procédé de blanchiment de pâte de cellulose au sulfate, utilisé pour donner à cette dernière un degré de blancheur d'au moins 85 ISO à l'aide d'au moins deux des produits chimiques de blanchiment suivants: oxygène, ozone et peroxyde. Ledit procédé se caractérise en ce que la pâte à papier est traitée dans un lessiveur; puis soumise à un traitement d'extraction des métaux lourds à l'aide d'au moins un des agents ou procédés de traitement suivants: acidification, EDTA et DTPA; délignifiée dans une phase à l'oxygène en deux étapes sous pression; et blanchie dans une phase au peroxyde acide.
PCT/FI1995/000506 1994-09-19 1995-09-18 Procede de blanchiment de pate kraft WO1996009434A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
CA002200327A CA2200327C (fr) 1994-09-19 1995-09-18 Procede de blanchiment de pate kraft
FI971023A FI971023A (fi) 1994-09-19 1997-03-11 Menetelmä kraft-massan valkaisemiseksi
SE9700992A SE9700992L (sv) 1994-09-19 1997-03-18 Förfarande för blekning av kraftmassa

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI944348 1994-09-19
FI944348A FI944348A (fi) 1994-09-19 1994-09-19 Menetelmä kraft-massan valkaisemiseksi

Publications (1)

Publication Number Publication Date
WO1996009434A1 true WO1996009434A1 (fr) 1996-03-28

Family

ID=8541400

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI1995/000506 WO1996009434A1 (fr) 1994-09-19 1995-09-18 Procede de blanchiment de pate kraft

Country Status (4)

Country Link
CA (1) CA2200327C (fr)
FI (1) FI944348A (fr)
SE (1) SE9700992L (fr)
WO (1) WO1996009434A1 (fr)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003000983A1 (fr) * 2001-06-25 2003-01-03 Nile Fiber Pulp & Paper, Inc. Lessivage totalement exempt de chlore de la pate d'arundo donax
US6761798B2 (en) 1998-06-17 2004-07-13 Nile Fiber Pulp & Paper, Inc. Method for forming an Arundo donax paper product
US9512561B2 (en) 2009-05-28 2016-12-06 Gp Cellulose Gmbh Modified cellulose from chemical kraft fiber and methods of making and using the same
US9512563B2 (en) 2009-05-28 2016-12-06 Gp Cellulose Gmbh Surface treated modified cellulose from chemical kraft fiber and methods of making and using same
US9512237B2 (en) 2009-05-28 2016-12-06 Gp Cellulose Gmbh Method for inhibiting the growth of microbes with a modified cellulose fiber
US9511167B2 (en) 2009-05-28 2016-12-06 Gp Cellulose Gmbh Modified cellulose from chemical kraft fiber and methods of making and using the same
US9617686B2 (en) 2012-04-18 2017-04-11 Gp Cellulose Gmbh Use of surfactant to treat pulp and improve the incorporation of kraft pulp into fiber for the production of viscose and other secondary fiber products
US9719208B2 (en) 2011-05-23 2017-08-01 Gp Cellulose Gmbh Low viscosity kraft fiber having reduced yellowing properties and methods of making and using the same
US9951470B2 (en) 2013-03-15 2018-04-24 Gp Cellulose Gmbh Low viscosity kraft fiber having an enhanced carboxyl content and methods of making and using the same
US10000890B2 (en) 2012-01-12 2018-06-19 Gp Cellulose Gmbh Low viscosity kraft fiber having reduced yellowing properties and methods of making and using the same
US10138598B2 (en) 2013-03-14 2018-11-27 Gp Cellulose Gmbh Method of making a highly functional, low viscosity kraft fiber using an acidic bleaching sequence and a fiber made by the process
US10151064B2 (en) 2013-02-08 2018-12-11 Gp Cellulose Gmbh Softwood kraft fiber having an improved α-cellulose content and its use in the production of chemical cellulose products
US10865519B2 (en) 2016-11-16 2020-12-15 Gp Cellulose Gmbh Modified cellulose from chemical fiber and methods of making and using the same

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4222819A (en) * 1978-02-17 1980-09-16 Mo Och Domsjo Aktiebolag Process for the acid bleaching of cellulose pulp with peroxides
US4427490A (en) * 1978-04-07 1984-01-24 International Paper Company Delignification and bleaching process for lignocellulosic pulp with peroxide in the presence of metal additives
US4626319A (en) * 1984-08-01 1986-12-02 Degussa Aktiengesellschaft Process for the delignification and acid bleaching of cellulose with oxygen and hydrogen peroxide
EP0433138A1 (fr) * 1989-12-11 1991-06-19 La Cellulose Du Pin Procédé de blanchiment de pâtes cellulosiques chimiques

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4222819A (en) * 1978-02-17 1980-09-16 Mo Och Domsjo Aktiebolag Process for the acid bleaching of cellulose pulp with peroxides
US4427490A (en) * 1978-04-07 1984-01-24 International Paper Company Delignification and bleaching process for lignocellulosic pulp with peroxide in the presence of metal additives
US4626319A (en) * 1984-08-01 1986-12-02 Degussa Aktiengesellschaft Process for the delignification and acid bleaching of cellulose with oxygen and hydrogen peroxide
EP0433138A1 (fr) * 1989-12-11 1991-06-19 La Cellulose Du Pin Procédé de blanchiment de pâtes cellulosiques chimiques

Cited By (30)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6761798B2 (en) 1998-06-17 2004-07-13 Nile Fiber Pulp & Paper, Inc. Method for forming an Arundo donax paper product
WO2003000983A1 (fr) * 2001-06-25 2003-01-03 Nile Fiber Pulp & Paper, Inc. Lessivage totalement exempt de chlore de la pate d'arundo donax
US9909257B2 (en) 2009-05-28 2018-03-06 Gp Cellulose Gmbh Modified cellulose from chemical kraft fiber and methods of making and using the same
US9926666B2 (en) 2009-05-28 2018-03-27 Gp Cellulose Gmbh Modified cellulose from chemical kraft fiber and methods of making and using the same
US9512237B2 (en) 2009-05-28 2016-12-06 Gp Cellulose Gmbh Method for inhibiting the growth of microbes with a modified cellulose fiber
US9512562B2 (en) 2009-05-28 2016-12-06 Gp Cellulose Gmbh Modified cellulose from chemical kraft fiber and methods of making and using the same
US9511167B2 (en) 2009-05-28 2016-12-06 Gp Cellulose Gmbh Modified cellulose from chemical kraft fiber and methods of making and using the same
US9512561B2 (en) 2009-05-28 2016-12-06 Gp Cellulose Gmbh Modified cellulose from chemical kraft fiber and methods of making and using the same
US10731293B2 (en) 2009-05-28 2020-08-04 Gp Cellulose Gmbh Modified cellulose from chemical kraft fiber and methods of making and using the same
US9777432B2 (en) 2009-05-28 2017-10-03 Gp Cellulose Gmbh Modified cellulose from chemical kraft fiber and methods of making and using the same
US11111628B2 (en) 2009-05-28 2021-09-07 Gp Cellulose Gmbh Modified cellulose from chemical kraft fiber and methods of making and using the same
US9512563B2 (en) 2009-05-28 2016-12-06 Gp Cellulose Gmbh Surface treated modified cellulose from chemical kraft fiber and methods of making and using same
USRE49570E1 (en) 2009-05-28 2023-07-04 Gp Cellulose Gmbh Modified cellulose from chemical kraft fiber and methods of making and using the same
US9970158B2 (en) 2009-05-28 2018-05-15 Gp Cellulose Gmbh Modified cellulose from chemical kraft fiber and methods of making and using the same
US10106927B2 (en) 2009-05-28 2018-10-23 Gp Cellulose Gmbh Modified cellulose from chemical kraft fiber and methods of making and using the same
US9719208B2 (en) 2011-05-23 2017-08-01 Gp Cellulose Gmbh Low viscosity kraft fiber having reduced yellowing properties and methods of making and using the same
US10294613B2 (en) 2011-05-23 2019-05-21 Gp Cellulose Gmbh Softwood kraft fiber having improved whiteness and brightness and methods of making and using the same technical field
US10000890B2 (en) 2012-01-12 2018-06-19 Gp Cellulose Gmbh Low viscosity kraft fiber having reduced yellowing properties and methods of making and using the same
US10597819B2 (en) 2012-01-12 2020-03-24 Gp Cellulose Gmbh Low viscosity kraft fiber having reduced yellowing properties and methods of making and using the same
US10995453B2 (en) 2012-01-12 2021-05-04 Gp Cellulose Gmbh Low viscosity kraft fiber having reduced yellowing properties and methods of making and using the same
US9617686B2 (en) 2012-04-18 2017-04-11 Gp Cellulose Gmbh Use of surfactant to treat pulp and improve the incorporation of kraft pulp into fiber for the production of viscose and other secondary fiber products
US10407830B2 (en) 2012-04-18 2019-09-10 Gp Cellulose Gmbh Use of surfactant to treat pulp and improve the incorporation of kraft pulp into fiber for the production of viscose and other secondary fiber products
US10151064B2 (en) 2013-02-08 2018-12-11 Gp Cellulose Gmbh Softwood kraft fiber having an improved α-cellulose content and its use in the production of chemical cellulose products
US10138598B2 (en) 2013-03-14 2018-11-27 Gp Cellulose Gmbh Method of making a highly functional, low viscosity kraft fiber using an acidic bleaching sequence and a fiber made by the process
US10550516B2 (en) 2013-03-15 2020-02-04 Gp Cellulose Gmbh Low viscosity kraft fiber having an enhanced carboxyl content and methods of making and using the same
US10294614B2 (en) 2013-03-15 2019-05-21 Gp Cellulose Gmbh Low viscosity kraft fiber having an enhanced carboxyl content and methods of making and using the same
US10174455B2 (en) 2013-03-15 2019-01-08 Gp Cellulose Gmbh Low viscosity kraft fiber having an enhanced carboxyl content and methods of making and using the same
US10753043B2 (en) 2013-03-15 2020-08-25 Gp Cellulose Gmbh Low viscosity kraft fiber having an enhanced carboxyl content and methods of making and using the same
US9951470B2 (en) 2013-03-15 2018-04-24 Gp Cellulose Gmbh Low viscosity kraft fiber having an enhanced carboxyl content and methods of making and using the same
US10865519B2 (en) 2016-11-16 2020-12-15 Gp Cellulose Gmbh Modified cellulose from chemical fiber and methods of making and using the same

Also Published As

Publication number Publication date
CA2200327C (fr) 2002-03-19
FI944348A (fi) 1996-03-20
CA2200327A1 (fr) 1996-03-28
SE9700992D0 (sv) 1997-03-18
SE9700992L (sv) 1997-05-16
FI944348A0 (fi) 1994-09-19

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