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WO2009003770A1 - Procédé de fabrication de papier et utilisation d'un traitement acide/base dans la fabrication de papier - Google Patents

Procédé de fabrication de papier et utilisation d'un traitement acide/base dans la fabrication de papier Download PDF

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Publication number
WO2009003770A1
WO2009003770A1 PCT/EP2008/056463 EP2008056463W WO2009003770A1 WO 2009003770 A1 WO2009003770 A1 WO 2009003770A1 EP 2008056463 W EP2008056463 W EP 2008056463W WO 2009003770 A1 WO2009003770 A1 WO 2009003770A1
Authority
WO
WIPO (PCT)
Prior art keywords
pulp
acid
suspension
water
process according
Prior art date
Application number
PCT/EP2008/056463
Other languages
English (en)
Inventor
Aila Weaver
Risto Vahteri
Original Assignee
Linde Aktiengesellschaft
Stora Enso Oyj
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 Linde Aktiengesellschaft, Stora Enso Oyj filed Critical Linde Aktiengesellschaft
Priority to CA002691590A priority Critical patent/CA2691590A1/fr
Priority to EP08760061A priority patent/EP2176461B1/fr
Priority to AT08760061T priority patent/ATE515593T1/de
Publication of WO2009003770A1 publication Critical patent/WO2009003770A1/fr

Links

Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/63—Inorganic compounds
    • D21H17/64—Alkaline 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
    • D21C9/001—Modification of pulp properties
    • D21C9/002—Modification of pulp properties by chemical means; preparation of dewatered pulp, e.g. in sheet or bulk form, containing special additives
    • D21C9/004—Modification of pulp properties by chemical means; preparation of dewatered pulp, e.g. in sheet or bulk form, containing special additives inorganic compounds
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/63—Inorganic compounds
    • D21H17/65—Acid compounds
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
    • D21H23/76—Processes or apparatus for adding material to the pulp or to the paper characterised by choice of auxiliary compounds which are added separately from at least one other compound, e.g. to improve the incorporation of the latter or to obtain an enhanced combined effect
    • 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
    • D21C9/1036—Use of compounds accelerating or improving the efficiency of the processes
    • 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
    • D21C9/18—De-watering; Elimination of cooking or pulp-treating liquors from the pulp

Definitions

  • the present invention relates to a process for making paper, wherein a pulp suspension, which comprises mechanical pulp, is thickened in a dewatering device and is thereafter diluted with water and pumped to a storage tank, then diluted again and made into paper.
  • the pulp suspension is subjected to an acid-base treatment after said dewatering device.
  • the invention also relates to the use of an acid-base treatment in a process for making paper, wherein a pulp suspension, which has been thickened in a dewatering device, is subjected to an acid-base treatment for improving the process and/or the product.
  • the invention provides improvements in the brightness of the pulp suspension and/or reduces the need for bleaching agent.
  • the invention also decreases the dissolution of calcium carbonate filler in the process.
  • Mechanical pulps may be used in unbleached form, but they are typically subjected to bleaching with peroxide and/or dithionite to increase the brightness of the pulp. After peroxide bleaching the pulp suspension is subjected to a thickening step and thereafter it is diluted with process water. Alternatively, in the case of unbleached pulp the suspension is subjected, after the screening and washing stage, directly to a thickening step and then to dilution with process water.
  • the pH of the mechanical pulp is commonly reduced in order to minimize the darkening reactions of the pulp that decrease the brightness of the pulp and of the paper made from that pulp. These reactions include precipitation of dissolved substances together with metals, lignin etc. How severe these reactions are depend on pH, time, temperature, amount of dissolved metals and amount of dissolved and colloidal organic material.
  • the pulp is normally acidified to pH 5-7 with sulphur dioxide water, bisulphite, sulphuric acid or carbon dioxide. Pulps used in acidic papermaking can be acidified to a lower pH than pulps that are used in neutral papermaking. A lower pH gives less brightness loss, however a too low pH can cause problems directly at the point of addition of the acid or later in the process.
  • a low pH may cause dissolution of calcium carbonate and the pH may be too low to give optimum performance for chemicals that are added later or at the same time as the acid, for example dithionite, different retention and sizing systems, etc. Due to these conflicting needs of the process, a non-optimised pH for brightness is typically used.
  • the circulating process water systems of present day pulp and paper mills are closed to a more and more increased level in order to lower the amount of water discharged from the pulping and the papermaking processes.
  • Various impurities enter and accumulate in the water circulations in different phases of the process.
  • Organic impurities dissolve from the fiber raw material and inorganic and organic chemicals are added to the process in different production steps.
  • calcium hardness of recycled paper-processing water is controlled by precipitating calcium ion in process water into calcium carbonate through addition of sodium carbonate or sodium hydrogen carbonate to white water short - circulated in a papermaking process and removing the calcium carbonate precipitate from the water.
  • Air or carbon dioxide may be used for removal of the precipitate by flotation.
  • US 3,639,206 describes removal of ligneous colour bodies and suspended fibrous material, whereby waste water effluent is treated first with a calcium salt (CaO, Ca(OH) 2 ). The separated aqueous phase is then contacted with CO 2 gas to precipitate any dissolved calcium salts and a final separation is performed.
  • a calcium salt CaO, Ca(OH) 2
  • US 5,679,220 discloses a method enhancing the deposition and retention of particulate filler on papermaking fibers wherein separate slurries of fibers and Ca(OH) 2 or equivalent thereof are combined with gaseous precipitant (CO 2 ) to form in situ calcium carbonate on the fibers.
  • gaseous precipitant CO 2
  • precipitation of gypsum in an alkaline recycle or broke derived pulp may be prevented by adding carbon dioxide to form bicarbonate ions in the alkaline pulp and to precipitate calcium as carbonate.
  • the pH of a pulp suspension in the stock preparation of a paper machine is stabilized by carbon dioxide.
  • a combination of sodium hydroxide and carbon dioxide provide a significant buffering effect in the pulp.
  • the stabilized pH reduces the dissolution of calcium carbonate at acidic addition points.
  • an apparatus located outside the main process stream is used for combining sodium hydroxide and carbon dioxide at a desired ratio.
  • the resulting non- stochiometric sodium bicarbonate solution has a desired pH value and a desired buffering ability and it can be used for stabilizing the pH of the process and for reducing the calcium hardness of the process waters.
  • An object of the present invention is to reduce the problems of the prior art and to provide a process which does not impair the brightness of a mechanical pulp suspension.
  • Another object of the present invention is to reduce the problems caused by calcium ions in a mechanical pulp suspension.
  • a further object of the invention is to provide a technically advantageous process for maintaining the brightness of a mechanical pulp suspension after dilution with process water.
  • the present invention is based on the realization that subjecting a pulp suspension comprising mechanical pulp to an acid-base treatment reduces the risk for brightness loss in the pulp suspension while avoiding excess accumulation of calcium ions in the circulation.
  • an acid-base treatment of a diluted pulp provides both an improvement in the brightness and a reduction in the calcium ion level in the system.
  • the present invention relates to a process for making paper, wherein a pulp suspension, which comprises mechanical pulp, is thickened in a dewatering device and is thereafter diluted with water and pumped to a storage tank, then diluted again and made into paper.
  • the invention is characterized by subjecting said pulp suspension to an acid- base treatment, wherein the pH of said suspension is first reduced with a strong acid by 0.5-4 pH units to a pH between 4 and 6 and then the pH of said suspension is increased with a weak base by 0.5-3 units to a pH below 8, and wherein said acid is added in connection with said dilution after said dewatering device and said weak base is added before said storage tank or in connection with the first dilution after said storage tank.
  • the pulp suspension which is to be treated according to the invention is a suspension which contains or consists of mechanical pulp in water.
  • the mechanical pulps in question may be bleached or unbleached and they may be selected from stone groundwood, pressurized groundwood, refiner mechanical pulp, thermomechanical pulp, chemithermomechanical pulp, chemimechanical pulp and combinations thereof.
  • the pulp suspension consists of bleached mechanical pulp.
  • the present invention also relates to the use of an acid-base treatment in a process for making paper form a pulp suspension comprising mechanical pulp.
  • the pulp suspension which has been thickened in a dewatering device, is subjected to an acid-base treatment, wherein the pH of said suspension is first reduced with a strong acid by 0.5-4 pH units to a pH between 4 and 6 and then the pH of said suspension is increased with a weak base by 0.5-3 units to a pH below 8, and wherein said acid is added in connection with a dilution after said dewatering device and said weak base is added before a subsequent storage tank or in connection with the first dilution after said storage tank.
  • the acid-base treatment of the present invention can be utilized in many ways, e.g for adjusting the brightness of the pulp, for reducing the amount of bleaching agent, for reducing the dissolution of calcium carbonate and diminishing the amount of detrimental substances in the process waters.
  • Fig. 1 shows a schematic diagram of an acid/base treatment in a mechanical pulp bleaching process
  • the present invention relates especially to pulps comprising mechanical pulps, and it aims at solving the problem posed by the conflicting needs of providing a low enough pH for obtaining an acceptable brightness, on one hand, and a high enough pH for allowing use of calcium carbonate and other substances, on the other hand.
  • the acid-base treatment of the present invention is located in the process at the stage wherein the mechanical pulp has been produced and optionally bleached and then washed in one or more washing stages.
  • the washed pulp is then thickened in a dewatering device.
  • the thickened pulp is diluted with re-circulated process water in order to facilitate its pumping forward in the process.
  • the process water is typically selected from white water, clear filtrate, bleaching filtrate and mixtures of any of these. Fresh water may also be used as such or added to any of the said process waters.
  • the acid according to the invention is added to the pulp in connection with this dilution.
  • the acid that is used according to the invention is a strong acid. It is typically selected from the group consisting of sulphuric acid, sulphurous acid , hydrochloric acid and bisulphite.
  • the preferred acid is sulphurous acid that is added in the form of SO 2 water. SO 2 in water forms sulphurous acid H2SO3, which dissociates into H + and HSO3 ' Thus SO 2 also inherently forms the bisulphite ion. At pH 4, the acid is almost exclusively in the bisulphite form. When bisulphite is added as such, it is typically added as sodium bisulphite. It has been found that adding a weak acid such as carbon dioxide will not provide the desired reduction in brightness loss of the mechanical pulp.
  • Addition of the strong acid in connection with the dilution facilitates uniform mixing of the strong acid throughout the suspension. A uniform distribution is desired in order to avoid local areas of too low or too high pH.
  • the amount of strong acid depends on the desired pH reduction, which in turn depends on the process pH as a whole.
  • a non-bleached mechanical pulp will typically have a pH of 4.5 to 5.5 and the pH may again vary due to washing and dilution with process water having a different pH.
  • the pH of the circulating process water used for dilution will typically have a pH of 4.5 to 5.5, while the waters of a neutral papermaking process typically have pH values between 6.8 and 8.5.
  • the pH of the pulp will initially be low and a lowering of the pH by as little as 0.5 pH units may be sufficient for providing the desired results.
  • the pH will initially be higher and lowering the pH to a desired value between 4 and 6 will require a substantially larger amount of acid.
  • the person skilled in the art is able to adjust the amount of acid according to the desired pH.
  • the pH of the pulp suspension may be increased by a non- stoichiometric sodium bicarbonate solution having a pH higher or lower than that of stoichiometric bicarbonate.
  • the bicarbonate solution may be produced on site as described in EP-Bl 991 811 and in US-B2 7,175,759.
  • the concentration of the bicarbonate solution is typically between 2 and 8 % and its pH is typically 8 to 9, preferably 8.3-8.5.
  • the pH of the pulp suspension is first reduced with a strong acid by 0.5-4 pH units to a pH between 4 and 6, typically to a pH between 5 and 6 in a neutral process, and then the pH of said suspension is increased with a weak base by 0.5-3 units to a pH which is below 8 and typically is between 6 and 7.5 in a neutral process.
  • acidic paper making the pH is typically reduced with the acid to a value between 4 and 5 and then increased to a value between 5 and 6.
  • the pH reduction with the strong acid precipitates impurities in the pulp suspension and the subsequent pH increase with the weak base allows the precipitated impurities to remain substantially undissolved in the suspension while raising the pH to suit the rest of the process.
  • the acid-base treatment works as a "fixative" by decreasing the amount of organic substances, such as extractives, and metals in the process waters.
  • the impurities precipitate on the pulp fibres with the pH reduction caused by the strong acid and remain substantially precipitated when the pH is raised with the weak base. The precipitations leave the system with the pulp and the circulation waters become cleaner.
  • the terms “significant” and “low” used for the content or amount of calcium carbonate in a liquid refers more to the amount present in functional terms more than as an absolute value.
  • the amount of calcium carbonate in a dilution water is significant if it causes variations or fluctuations in the pH of the suspension which it dilutes and/or if it causes a substantial buffering ability in the suspension.
  • the amount of calcium carbonate in a dilution water is considered low, if it does not influence the pH or buffering ability of the resulting suspension.
  • the amount of calcium carbonate in dilution water is typically calculated based on the amount of solids per liter.
  • the solids include, besides filler, also other solids such as fibers.
  • One embodiment of this invention relates to peroxide bleached mechanical pulps that are used in neutral papermaking.
  • the washing steps include dewatering devices such as disc filters or washing presses.
  • the dewatered thickened pulp is diluted with process water to a consistency between 5 and 15% and pumped to a storage tank.
  • the strong acid is added in connection with the dilution after the last washing step.
  • the pH in this embodiment is decreased to at least a pH of 6 and preferably to a pH between 5.3 and 5.8.
  • the weak base is added either before the storage tank or immediately after the tank. When a short acid dwell time is desired, it has been found advantageous to add the acid on the suction side of a pump and the base on the pressure side of the pump. After the addition of base the pH should be at least 5.7 and preferably at a pH between 6 and 7.
  • the paper mill in example 5 changed the treatment after the peroxide bleaching to try to decrease the amount of peroxide needed by using an acid-base treatment using an acidic shock with sulphurous acid followed by an increase in pH with NaHCO 3 .
  • the cleaned pulp was dewatered and then diluted with process water and the pH was decreased with SO 2 to pH 4. Shortly thereafter, within about 2 minutes, the pH was increased again with NaHCOs to pH 5. After that dithionite was added for further bleaching and the pulp was pumped to the storage tower.
  • the amounts of peroxide needed could be decreased with 20% while keeping the same brightness of the pulp as in example
  • a paper mill was producing paper from mechanical pulp according to the schematic diagram of Fig. 1.
  • the mill used calcium carbonate as filler in a neutral papermaking process having pH 7 to 8 in the head box.
  • the mechanical pulp 1 was peroxide bleached in bleach tower 2 and directly after the peroxide bleaching it was washed in washer 4 to clean the pulp. Washing water 5 was recirculated up-stream in the process. After the washing step the cleaned pulp was dewatered in a thickener 6, from which the pulp was fed forward in the process and the removed water 7 was recirculated up-stream. The dewatered pulp was diluted with process water 8 comprising a mixture of clear filtrate and white water to a consistency of 7-8.
  • the pulp was then fed to storage tower 13 where the storage time was about 2 to.6 hours. After the storage tower the pulp was further diluted with process water and bicarbonate solution to bring the consistency and pH to the desired value for the subsequent neutral papermaking.
  • the resulting pulp had an acceptable brightness and the level of calcium ions in the system was kept at an acceptable level.
  • the process produced paper of good quality with reduced amounts of bleaching agents compared to a similar process without the acid-base treatment.

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  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
  • Paper (AREA)

Abstract

La présente invention concerne un procédé de fabrication de papier dans lequel une suspension de pâte (qui inclue de la pâte mécanique) est épaissie dans un deshydrateur puis diluée avec de l'eau et enfin pompée dans un réservoir de stockage pour être à nouveau diluée afin d'être transformée en papier. Selon l'invention la suspension de pâte est soumise à un traitement acide/base après avoir été mise dans le deshydrateur. Le pH de la suspension est tout d'abord diminué au moyen d'un puissant acide passant d'un pH à 0,5-4 unités à un pH compris entre 4 et 6. Le pH de la suspension est ensuite augmenté au moyen d'une base faible passant d'un pH compris entre 0,5 et 3 unités à un pH inférieur à 8. L'invention concerne également l'utilisation d'un traitement acide/base dans le procédé de fabrication de papier, procédé dans lequel une suspension de pâte qui a été épaissie dans un deshydrateur est soumise à un traitement acide/base afin d'améliorer le procédé et/ou le produit. L'invention permet d'améliorer l'indice de blancheur de la suspension de pâte et/ou de réduire le besoin d'agent de blanchiment. L'invention permet enfin de diminuer, au cours du procédé, la dissolution d'une charge de carbonate de calcium.
PCT/EP2008/056463 2007-07-03 2008-05-27 Procédé de fabrication de papier et utilisation d'un traitement acide/base dans la fabrication de papier WO2009003770A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
CA002691590A CA2691590A1 (fr) 2007-07-03 2008-05-27 Procede de fabrication de papier et utilisation d'un traitement acide/base dans sa fabrication
EP08760061A EP2176461B1 (fr) 2007-07-03 2008-05-27 Procédé de fabrication de papier et utilisation d'un traitement acide/base dans sa fabrication
AT08760061T ATE515593T1 (de) 2007-07-03 2008-05-27 Verfahren zur herstellung von papier und verwendung einer säure/base-behandlung bei der papierherstellung

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI20075503A FI20075503A7 (fi) 2007-07-03 2007-07-03 Menetelmä paperin valmistamiseksi ja happo/emäskäsittelyn käyttö paperin valmistuksessa
FI20075503 2007-07-03

Publications (1)

Publication Number Publication Date
WO2009003770A1 true WO2009003770A1 (fr) 2009-01-08

Family

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Family Applications (1)

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PCT/EP2008/056463 WO2009003770A1 (fr) 2007-07-03 2008-05-27 Procédé de fabrication de papier et utilisation d'un traitement acide/base dans la fabrication de papier

Country Status (5)

Country Link
EP (1) EP2176461B1 (fr)
AT (1) ATE515593T1 (fr)
CA (1) CA2691590A1 (fr)
FI (1) FI20075503A7 (fr)
WO (1) WO2009003770A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120186766A1 (en) * 2011-01-25 2012-07-26 Basf Se Manufacturing a papery article
US20120186762A1 (en) * 2011-01-25 2012-07-26 Basf Se Producing half-stuffs for the manufacture of papery articles
WO2012101138A2 (fr) 2011-01-25 2012-08-02 Basf Se Procédé de préparation de demi-pâtes pour la production d'articles en papier
WO2012101137A1 (fr) 2011-01-25 2012-08-02 Basf Se Procédé de fabrication d'un produit de type papier

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3639206A (en) * 1969-07-29 1972-02-01 Continental Can Co Treatment of waste water from alkaline pulping processes
GB2008562A (en) * 1977-11-24 1979-06-06 Voith Gmbh J M Water harening for waste paper treatment
WO1988004706A1 (fr) * 1986-12-22 1988-06-30 Aga Aktiebolag Procede de lavage des pates alcalines
US5262006A (en) * 1989-02-13 1993-11-16 Mo Och Domsjo Aktibolag Paper manufacturing process, and papers obtainable by means of that process
WO1997022749A1 (fr) * 1995-12-19 1997-06-26 Kvaerner Hymac Inc. Procede de traitement de pate de raffineur
US5679220A (en) * 1995-01-19 1997-10-21 International Paper Company Process for enhanced deposition and retention of particulate filler on papermaking fibers
WO1999000545A1 (fr) * 1997-06-30 1999-01-07 Sunds Defibrator Industries Ab Procede de reduction de la teneur en calcium de la phase liquide d'une suspension de pate a papier
EP0981665A1 (fr) * 1998-03-03 2000-03-01 Aga Aktiebolag Procedes ameliores de fabrication du papier
EP0991811A1 (fr) * 1997-06-13 2000-04-12 Aga Aktiebolag PROCEDE SERVANT A STABILISER LE pH D'UNE SUSPENSION DE PATE A PAPIER ET A FABRIQUER DU PAPIER A PARTIR DE CETTE PATE A PAPIER STABILISEE
EP1008561A2 (fr) * 1998-12-08 2000-06-14 Korea Research Institute Of Chemical Technology Technologie pour réduire la dureté calcaire de l'eau recyclée des machines à papier

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3639206A (en) * 1969-07-29 1972-02-01 Continental Can Co Treatment of waste water from alkaline pulping processes
GB2008562A (en) * 1977-11-24 1979-06-06 Voith Gmbh J M Water harening for waste paper treatment
WO1988004706A1 (fr) * 1986-12-22 1988-06-30 Aga Aktiebolag Procede de lavage des pates alcalines
US5262006A (en) * 1989-02-13 1993-11-16 Mo Och Domsjo Aktibolag Paper manufacturing process, and papers obtainable by means of that process
US5679220A (en) * 1995-01-19 1997-10-21 International Paper Company Process for enhanced deposition and retention of particulate filler on papermaking fibers
WO1997022749A1 (fr) * 1995-12-19 1997-06-26 Kvaerner Hymac Inc. Procede de traitement de pate de raffineur
EP0991811A1 (fr) * 1997-06-13 2000-04-12 Aga Aktiebolag PROCEDE SERVANT A STABILISER LE pH D'UNE SUSPENSION DE PATE A PAPIER ET A FABRIQUER DU PAPIER A PARTIR DE CETTE PATE A PAPIER STABILISEE
WO1999000545A1 (fr) * 1997-06-30 1999-01-07 Sunds Defibrator Industries Ab Procede de reduction de la teneur en calcium de la phase liquide d'une suspension de pate a papier
EP0981665A1 (fr) * 1998-03-03 2000-03-01 Aga Aktiebolag Procedes ameliores de fabrication du papier
EP1008561A2 (fr) * 1998-12-08 2000-06-14 Korea Research Institute Of Chemical Technology Technologie pour réduire la dureté calcaire de l'eau recyclée des machines à papier

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120186766A1 (en) * 2011-01-25 2012-07-26 Basf Se Manufacturing a papery article
US20120186762A1 (en) * 2011-01-25 2012-07-26 Basf Se Producing half-stuffs for the manufacture of papery articles
WO2012101138A2 (fr) 2011-01-25 2012-08-02 Basf Se Procédé de préparation de demi-pâtes pour la production d'articles en papier
WO2012101137A1 (fr) 2011-01-25 2012-08-02 Basf Se Procédé de fabrication d'un produit de type papier

Also Published As

Publication number Publication date
FI20075503A0 (fi) 2007-07-03
CA2691590A1 (fr) 2009-01-08
ATE515593T1 (de) 2011-07-15
FI20075503L (fi) 2008-06-19
EP2176461B1 (fr) 2011-07-06
EP2176461A1 (fr) 2010-04-21
FI20075503A7 (fi) 2008-06-19

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