EP0056263B1 - Procédé pour améliorer le lavage de pâtes cellulosiques préparées en partant d'une matière lignocellulosique - Google Patents

Procédé pour améliorer le lavage de pâtes cellulosiques préparées en partant d'une matière lignocellulosique Download PDF

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Publication number
EP0056263B1
EP0056263B1 EP82100102A EP82100102A EP0056263B1 EP 0056263 B1 EP0056263 B1 EP 0056263B1 EP 82100102 A EP82100102 A EP 82100102A EP 82100102 A EP82100102 A EP 82100102A EP 0056263 B1 EP0056263 B1 EP 0056263B1
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EP
European Patent Office
Prior art keywords
pulp
washing
mild mechanical
stages
washed
Prior art date
Legal status (The legal status 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 status listed.)
Expired
Application number
EP82100102A
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German (de)
English (en)
Other versions
EP0056263A1 (fr
Inventor
Jonas Arne Ingvar Lindahl
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mo och Domsjo AB
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Mo och Domsjo AB
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Filing date
Publication date
Application filed by Mo och Domsjo AB filed Critical Mo och Domsjo AB
Priority to AT82100102T priority Critical patent/ATE14762T1/de
Publication of EP0056263A1 publication Critical patent/EP0056263A1/fr
Application granted granted Critical
Publication of EP0056263B1 publication Critical patent/EP0056263B1/fr
Expired legal-status Critical Current

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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
    • D21C9/02—Washing ; Displacing cooking or pulp-treating liquors contained in the pulp by fluids, e.g. wash water or other pulp-treating agents
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
    • D21D1/00—Methods of beating or refining; Beaters of the Hollander type
    • D21D1/20—Methods of refining
    • D21D1/40—Washing the fibres

Definitions

  • the present invention relates to a method for washing cellulose pulps produced from lignocellulosic material more effectively than when applying known washing techniques, so as to improve the recovery of chemicals and combustible organic materials from the waste liquors.
  • cellulose pulp is meant primarily chemicals pulps, semi-chemical pulps and chemi-mechanical pulps produced from both softwood and hardwood.
  • the wood chips When producing cellulose pulps with a yield in excess of about 55%, the wood chips are normally mechanically defibrated to separate fibre form, prior to washing and/or screening the pulp. When screening the pulp, there is obtained a concentration of the non-defibrated wood residues, referred to as reject or tailings, which are normally defibrated in a separate stage to separate fibre form, and then returned to the pulp flow.
  • the pulp suspension obtained subsequent to delignifying the wood chips can be washed in accordance with a number of mutually differing methods known to the art.
  • the oldest method is one in which the pulp suspension is washed in so-called diffusers, i.e. a displacement wash which is carried out batchwise in large vessels.
  • the pulp suspension is washed on drum filters, normally in several stages. The number of drum filters may vary, although normally from three to four filters are used.
  • pulp is washed with the use of presses whereat greater volumes of liquid can be removed than when using filters, which results in a more effective recovery of chemicals and organic substances.
  • the present invention affords a solution to the aforementioned problems and makes possible an increase in the extent to which chemicals are recovered. Accordingly, the invention relates to a method for improving the washing of unbleached cellulose pulp when producing cellulose pulps from ligno-cellulosic material, by chemical delignification, in which the pulp suspension is washed in a plurality of stages while supplying water thereto, characterised in that the pulp, after having been partially washed so that at least 10% of the dry solids content of the cooking waste liquor is removed, is subjected between a pair of successive washing stages or between several successive washing stages to a mild mechanical working treatment in a device adapted for high-consistency treatment and provided with screws rotating relative to each other at an energy input of from 7 to 200 kWh per ton of bone-dry pulp.
  • pulp dry solids content prior to the mild mechanical treatment process it has also been found particularly suitable to increase the pulp dry solids content prior to the mild mechanical treatment process, to between 10% and 50%, preferably to between 14 and 40%, and suitably to between 20 and 35%.
  • the pulp suspension is diluted to a pulp consistency of between 0.5 and 13%, in conjunction with mixing with wash liquid in the subsequent washing step.
  • the most suitable pulp consistency lies between 0.5 and 6%, while washing-dewatering in, for example, a press is suitably performed at an input pulp consistency of between 2 and 13%.
  • the mild mechanical treatment process according to the invention can be carried out at all temperatures normally used in practice.
  • a particularly suitable temperature range is 20°-110°C, while a preferred range is 35°-90°C.
  • mild mechanical treatment is meant here a process in which pulp suspensions of the aforementioned dry solids contents are subjected to a repeated pressing, kneading and shearing treatment, whereat the input of electrical energy for carrying out said treatment is held within the range of 7 to 200 kWh per ton of bone-dry pulp, and preferably within the range of 10 to 100 kWh per ton of bone-dry pulp.
  • a screw-type defibrator of the kind comprising two rotatable, bladed screws which are arranged parallel to one another in a housing provided with an inlet and outlet, and which are in adjustable meshing engagement with one another, to provide the mild mechanical treatment of the material, as before described.
  • the screw blades of the rotatable screws also exhibit concave portions at the periphery of at least some of the screw turns, to form teeth-like protrusions between said concave portions.
  • Screw defibrators of the aforedescribed kind are sold by MoDoMekan AB under the registered trademark FROTAPULPER@.
  • the novel method according to the invention in which the pulp suspension is mechanically treated in a mild fashion between two or more of the stages of a washing sequence, has been surprisingly found to provide a cleaner pulp and to result in higher chemical recovery, a lower discharge of impurities to the surroundings and a higher dry solids content of the effluent washing water than was previously the case, when applying conventional washing techniques.
  • the present invention affords the important advantage of enabling a purer pulp to be obtained. This is manifested, inter alia, by a considerable lowering of the extractive content of the pulp and its kappa number.
  • the advantages afforded by the method according to the invention also include the possibility of increasing the dry solids content of the liquor departing from the pulp-washing stage, i.e. the amount of organic materials contained by said liquor, and also the amount of inorganic chemicals contained thereby.
  • This increases the fuel value of the washing liquid, representing a valuable saving on energy. Because more contaminants are brought to evaporation and burning, and a greater amount of chemicals are recovered, the amount of environmentally harmful substances contained in the effluent is less than would otherwise be the case, which is an important advantage, and also desirable from an environmental aspect. Consequently, the cost involved in the treatment and destruction of environmentally harmful substances in the effluent can be reduced when applying the invention.
  • a further advantageous and surprising effect afforded by the invention is that the consumption of bleaching chemicals, such as chlorine, chlorine dioxide, hypochlorite, hydrogen peroxide and oxygen gas is markedly reduced when bleaching the washed pulp.
  • bleaching chemicals such as chlorine, chlorine dioxide, hypochlorite, hydrogen peroxide and oxygen gas
  • Another surprising effect obtained by the inclusion of the mild mechanical treatment process according to the invention is that the dewatering of the resultant pulp suspension is markedly improved, a fact which affords decisive advantages when further treating the pulp.
  • the Figure illustrates schematically a suitable embodiment of the method according to the invention applied in washing tests with birch sulphate pulp and chemi-mechanical spruce pulp in three stages, each of said stages being equipped with a press.
  • a screw defibrator of the kind sold under the trademark FROTAPULPER@.
  • Unbleached and unwashed birch sulphate pulp was introduced through a line 1 into a tank 2, in which the pulp suspension was diluted with press waste liquor supplied through a line 22, until a pulp consistency of about 8% was obtained.
  • the pulp suspension was passed from the tank 2 through a line 3 to a first washing stage comprising a press 4, in which the pulp suspension was thickened to a dry solids content of 33.3% and then passed through a line 5, to a screw feeder 6, arranged to feed the pulp suspension through a line 7 and a line 8 to a screw defibrator 10 provided with two rotating screws whose blades exhibited concaved portions and in which the pulp suspension was subjected to a mild mechanical treatment process, whereafter said suspension was passed to a second screw feeder 12 through a line 11.
  • the temperature of the pulp suspension at the inlet to the screw defibrator 10 was measured as 68°C, and at the outlet of said defibrator as 71°C.
  • the amount of electrical energy consumed by the mild mechanical treatment process in the screw defibrator 10 was measured to 15 kWh per ton of bone-dry pulp.
  • the line 9 was closed while passing the pulp suspension through the defibrator 10.
  • the treated pulp suspension was diluted in the screw feeder 12 to a pulp consistency of 8%, by introducing press waste liquor to said feeder through a line 21, said waste liquor mixing effectively with the pulp suspension during its transport through the feeder 12.
  • the diluted pulp suspension was then passed through a line 13 to a second washing stage equipped with a press 14, comprising a press similar to that used in the first washing stage.
  • the pulp suspension was washed and again thickened in the press 14, to a dry solids content of 33.3%.
  • Waste liquor obtained from the press 14 was passed through a line 22 to the tank 2, where it was used to dilute incoming pulp suspension.
  • the pulp suspension, washed and thickened in the second washing stage was then passed through a line 15 to a screw feeder 16, and through a line 17 to a third washing stage equipped with a press 18 similar to the presses used in the two preceding washing stages.
  • the pulp suspension was diluted and mixed in the screw feeder 16 in a manner similar to that in the preceding screw feeder 12, although in this case with pure water supplied through a line 20, to obtain a pulp consistency of 8%. Subsequent to washing the pulp suspension and thickening the same to a dry solids content of 33.3% in the press 18, the finally washed pulp suspension was removed through a line 19.
  • Example 1 The test described in Example 1 was repeated with chemi-mechanical spruce pulp cooked to a pulp yield of 73%, calculated on absolute dry wood. After washing the pulp suspension and thickening the same in the press 14 of the second washing stage, there was obtained in this test a dry solids content of 34%. A dry solids content of 34% was similarly obtained after washing and thickening the pulp in the press 18 of the third washing stage. The line 9 was closed when making this test.

Landscapes

  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
  • Paper (AREA)
  • Polysaccharides And Polysaccharide Derivatives (AREA)
  • Processes Of Treating Macromolecular Substances (AREA)
  • Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)
  • Peptides Or Proteins (AREA)
  • Investigating Or Analysing Biological Materials (AREA)
  • Investigating Or Analysing Materials By The Use Of Chemical Reactions (AREA)

Claims (4)

1. Procédé pour améliorer le lavage de pâte cellulosique non blanchie lors de la fabrication de pâtes cellulosiques en partant de matière lignocellulosique par délignification chimique, procédé dans lequel on lave la suspension de pâte en plusieurs stades tout en y amenant de l'eau, caractérisé par le fait qu'après l'avoir lavée partiellement de façon qu'au moins 10% de la teneur en solides secs de la lessive résiduaire de cuisson soient éliminés, on soumet la pâte, entre deux stades successifs de lavage ou entre plusieurs stades successifs de lavage, à un traitement modéré de travail mécanique dans un appareil conçu pour le traitement à consistance élevée et muni de vis tournant l'une par rapport à l'autre, avec une fourniture d'énergie de 7 à 200 kWh par tonne de pâte absolument sèche.
2. Procédé selon la revendication 1, caractérisé par le fait que l'on effectue le processus de traitement mécanique modéré à une teneur en solides secs de la pâte comprise entre 10 et 50%, de préférence entre 14 et 40% et de préférence encore entre 20 et 35%.
3. Procédé selon l'une ou l'autre des revendications 1 ou 2, caractérisé par le fait que l'on maintient la fourniture d'énergie électrique au processus de traitement mécanique modéré dans la gamme de 10 à 100 kWh/t.
4. Procédé selon l'une quelconque des revendications 1 à 3, caractérisé par le fait que l'on conduit le processus de traitement mécanique modéré dans un défibreur à vis du genre comprenant deux vis à lames tournantes, qui sont disposées parallèlement l'une à l'autre dans une enveloppe munie d'une entrée et d'une sortie, qui s'engagent l'une dans l'autre pour traiter modérément la matière et dont les lames de vis présentent des parties concaves à la périphérie d'au moins certaines spires de vis pour former des saillies similaires à des dents entre les parties concaves.
EP82100102A 1981-01-14 1982-01-08 Procédé pour améliorer le lavage de pâtes cellulosiques préparées en partant d'une matière lignocellulosique Expired EP0056263B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT82100102T ATE14762T1 (de) 1981-01-14 1982-01-08 Verfahren zur verbesserung des waschens von cellulosepulpen, hergestellt aus lignocellulosematerial.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE8100179 1981-01-14
SE8100179A SE443383C (sv) 1981-01-14 1981-01-14 Forfarande for tvettning av cellulosamassa

Publications (2)

Publication Number Publication Date
EP0056263A1 EP0056263A1 (fr) 1982-07-21
EP0056263B1 true EP0056263B1 (fr) 1985-08-07

Family

ID=20342871

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82100102A Expired EP0056263B1 (fr) 1981-01-14 1982-01-08 Procédé pour améliorer le lavage de pâtes cellulosiques préparées en partant d'une matière lignocellulosique

Country Status (9)

Country Link
EP (1) EP0056263B1 (fr)
JP (1) JPS57139591A (fr)
AT (1) ATE14762T1 (fr)
AU (1) AU548277B2 (fr)
CA (1) CA1164704A (fr)
DE (1) DE3265116D1 (fr)
FI (1) FI69656C (fr)
NO (1) NO160219C (fr)
SE (1) SE443383C (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7658794B2 (en) 2000-03-14 2010-02-09 James Hardie Technology Limited Fiber cement building materials with low density additives
US7857906B2 (en) 2001-03-09 2010-12-28 James Hardie Technology Limited Fiber reinforced cement composite materials using chemically treated fibers with improved dispersibility
US7998571B2 (en) 2004-07-09 2011-08-16 James Hardie Technology Limited Composite cement article incorporating a powder coating and methods of making same
US8993462B2 (en) 2006-04-12 2015-03-31 James Hardie Technology Limited Surface sealed reinforced building element
EP1574614B1 (fr) 2000-10-17 2015-11-11 James Hardie Technology Limited Procédé pour réduire des impuretés dans des fibres cellulosiques pour la production des matériaux de ciment composites renforcés par des fibres

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE445051B (sv) * 1980-04-10 1986-05-26 Sca Development Ab Sett vid tillverkning av mekanisk, i huvudsak hartsfri cellulosamassa
FI77063B (fi) * 1986-12-17 1988-09-30 Ahlstroem Oy Foerfarande foer effektivering av fibersuspensionstvaett.
FI81136C (fi) * 1987-11-11 1990-09-10 Ahlstroem Oy Foerfarande och anordning foer behandling av massa.
US5554259A (en) 1993-10-01 1996-09-10 Union Camp Patent Holdings, Inc. Reduction of salt scale precipitation by control of process stream Ph and salt concentration
CA2424377C (fr) 2000-10-04 2013-07-09 Donald J. Merkley Materiaux composite de fibro-ciment utilisant des fibres cellulosiques calibrees
CZ20031253A3 (cs) * 2000-10-17 2004-12-15 James Hardie Research Pty Limited Způsob a zařízení pro snižování nečistot v celulózových vláknech určených pro výrobu cementových složených materiálů vyztužených vlákny
US7993570B2 (en) 2002-10-07 2011-08-09 James Hardie Technology Limited Durable medium-density fibre cement composite
EP1587767B1 (fr) 2003-01-09 2017-07-19 James Hardie Technology Limited Materiaux composites en fibrociment faisant appel a des fibres de cellulose blanchies et leur procédé de fabrication
DE102007036377A1 (de) * 2007-07-31 2009-02-05 Voith Patent Gmbh Einsatz von Wasch- und Schneckenpressen für die Rohmaterial- und Faserstoffwäsche
US8209927B2 (en) 2007-12-20 2012-07-03 James Hardie Technology Limited Structural fiber cement building materials
SE538262C2 (sv) 2014-06-26 2016-04-19 Valmet Oy Arrangemang för matning och tvättning av lignocellulosahaltigt material och system för tvåstegsanalys innefattandearrangemanget

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2451963A1 (fr) * 1979-03-22 1980-10-17 Creusot Loire Procede et installation de preparation et de lavage d'une pate a papier a partir d'une matiere lignocellulosique reduite en morceaux

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7658794B2 (en) 2000-03-14 2010-02-09 James Hardie Technology Limited Fiber cement building materials with low density additives
EP1574614B1 (fr) 2000-10-17 2015-11-11 James Hardie Technology Limited Procédé pour réduire des impuretés dans des fibres cellulosiques pour la production des matériaux de ciment composites renforcés par des fibres
US7857906B2 (en) 2001-03-09 2010-12-28 James Hardie Technology Limited Fiber reinforced cement composite materials using chemically treated fibers with improved dispersibility
US7998571B2 (en) 2004-07-09 2011-08-16 James Hardie Technology Limited Composite cement article incorporating a powder coating and methods of making same
US8993462B2 (en) 2006-04-12 2015-03-31 James Hardie Technology Limited Surface sealed reinforced building element

Also Published As

Publication number Publication date
FI69656B (fi) 1985-11-29
CA1164704A (fr) 1984-04-03
AU7917582A (en) 1982-07-22
ATE14762T1 (de) 1985-08-15
FI820005L (fi) 1982-07-15
JPS63557B2 (fr) 1988-01-07
AU548277B2 (en) 1985-12-05
DE3265116D1 (en) 1985-09-12
NO160219B (no) 1988-12-12
NO820095L (no) 1982-07-15
NO160219C (no) 1989-03-22
JPS57139591A (en) 1982-08-28
EP0056263A1 (fr) 1982-07-21
FI69656C (fi) 1991-12-24
SE8100179L (sv) 1982-07-15
SE443383B (sv) 1986-02-24
SE443383C (sv) 1987-11-16

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