WO1996005364A1 - Blanchiment de pate a papier chimique dans des conditions de sulfonation - Google Patents

Blanchiment de pate a papier chimique dans des conditions de sulfonation Download PDF

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Publication number
WO1996005364A1
WO1996005364A1 PCT/SE1995/000486 SE9500486W WO9605364A1 WO 1996005364 A1 WO1996005364 A1 WO 1996005364A1 SE 9500486 W SE9500486 W SE 9500486W WO 9605364 A1 WO9605364 A1 WO 9605364A1
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WO
WIPO (PCT)
Prior art keywords
bleaching
stage
sulphite
bar
acidic
Prior art date
Application number
PCT/SE1995/000486
Other languages
English (en)
Inventor
Petter Tibbling
Ulla EKSTRÖM
Erik Nilsson
Original Assignee
Kvaerner Pulping Ab
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 Kvaerner Pulping Ab filed Critical Kvaerner Pulping Ab
Priority to AU27558/95A priority Critical patent/AU2755895A/en
Publication of WO1996005364A1 publication Critical patent/WO1996005364A1/fr
Priority to FI970519A priority patent/FI970519A0/fi

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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
    • D21C9/1084—Bleaching ; Apparatus therefor with reducing 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

Definitions

  • the present invention relates to a method of bleaching chemical paper pulp in a bleaching sequence which comprises at least one acidic, sulphite-containing, reducing bleaching stage and at least one alkaline, oxidizing bleaching stage in arbitrary order. At least one of the said sulphite-containing stages is carried out under conditions which are in the main sulphonat ⁇ ing. This is brought about by optimizing the system parameters pressure, temperature, time, pH and sulphur charge in such a manner that a maximum proportion of water-soluble lignin is formed.
  • the bleaching sequence is preferably entirely free of chlorine, but one or more supplementary chlorine-containing stages can also be included.
  • a method of bleaching using hydrogen peroxide has been developed by the Swedish company EKA Nobel AB.
  • the method which goes under the name LIGNOX (see SE 8902058) , involves the unbleached pulp first being delignified with oxygen and then, after washing, being treated with EDTA or other suitable complex-forming agent (Q) in order to remove transition metals which are bound in the pulp.
  • Sulphuric acid is used as an acidifier in the complex-forming stage.
  • the EDTA stage is followed by an intensive peroxide-bleaching stage.
  • the quantity of hydrogen peroxide required for this method is relatively high, being 15 - 35 kg per ton of pulp, depending on the brightness desired and on the bleachability of the pulp.
  • the time required is long, being 4 hours or more, and the quantity of residual peroxide is significant. Only 40 - 60 % of the added peroxide is utilized. This method only achieves a limited increase in brightness to 80 - 82 ISO.
  • EKA Nobel's patent application SE 9101300 (SE 468 355) additionally describes a bleaching method in which complex-forming agents are used prior to an ozone or peroxide stage. This application principally relates to ozone being used directly after a complex-forming stage .
  • a method is developed in which internally generated sulphur compounds, which are available in the pulp mill, are utilized in order to provide, preferably in combination with hydrogen peroxide, pulps which have preferably been bleached entirely without using chlorine- containing chemicals, which method is characterized by the low chemical cost of ozone bleaching, by the relatively high quality pulp of peracetic acid/chlorine dioxide bleaching, and by the lower capital cost of pure peroxide bleaching.
  • the fact that the bleaching sequence is preferably intended to provide pulp which has been bleached entirely without using chlorine implies that it is preferred for the invention to be carried out as a part of a total bleaching sequence entirely without any chlorine-containing chemical.
  • the total bleaching sequence consists of a combination of acidic, sulphite-containing, reducing bleaching stages and alkaline, oxidizing bleaching stages.
  • the oxidizing stage (s) is/are (a) preferably pressurized peroxide stage (s) (PO) in accordance with SE 9301960, which means that it/they contain (s) peroxide and is/are carried out at a pressure at the top of the bleaching vessel exceeding 1 bar, preferably exceeding 1.2 bar, and more preferably exceeding 1.5 bar.
  • the pressure should exceed 3 bar, preferably exceed 4 bar, and more preferably exceed 5 bar.
  • the temperature should exceed 90°C, preferably be equal to or greater than 100°C, and more preferably be between 100 and 120°C.
  • the method is characterized by at least one of the acidic, sulphite-containing, reducing bleaching stages being carried out under conditions which are in the main sulphonating.
  • Sulphonation in this context means that SO2 is consumed while HSO3- groups enter as sub ⁇ stituents into the lignin fragments, whereupon water- soluble compounds of residual lignin arise in the pulp. This results in a substantial kappa reduction directly after washing.
  • That sulphonation is taking place can readily be established by the fact that the pH falls from an initial 4 - 6 to 3 - 4 , and by the fact that SO2 is consumed and that the kappa number falls.
  • the degree of sulphonation is defined for a given bleaching stage as (kappa ⁇ - kappa2) / appa!, where kappa ⁇ . is the kappa number entering the stage and kappa2 is the kappa number leaving the stage .
  • the sulphonating, acidic, sulphite-containing, reducing bleaching stages are carried out to a degree of sulphonation exceeding 10 %, preferably exceeding 20 %, and still more preferably to 40 - 80 %.
  • the reaction time for such a stage is 30 seconds - 120 minutes, preferably 5 - 120 minutes, and still more preferably 30 - 120 minutes.
  • the consumption of sulphur, calcula ⁇ ted as sulphur dioxide, during the sulphonating, acidic, sulphite-containing, reducing bleaching stages is 1 - 40 kg per ton of pulp, preferably 10 - 30 kg per ton of pulp.
  • the sulphonating conditions are accomplished in one or more sulphite stages by a pressure in the top of the bleaching vessel exceeding 1 bar (absolute) , preferably exceeding 1.2 bar, and more preferably exceeding 1.5 bar, and a pressure in the bottom of the bleaching vessel exceeding 2 bar, preferably between 3 and 15 bar, and more preferably between 5 - 10 bar, and also by a temperature exceeding 90°C, preferably equal to or greater than 100°C, and more preferably between 100 and 120°C.
  • Such a stage is designated (AR*) and should also contain complex-forming agents for metal elimination, for example EDTA, in accordance with the scheme (S0 2 + Q, E) or (S0 2 + Q) .
  • E designates alkaline extraction.
  • it can have a beneficial effect on the pulp quality not to allow the pH to fall below 3, preferably not below 3.5, in the sulphonating stage.
  • This can be effected by adding alkali, preferably NaOH, as the pH falls during the sulphonating stage.
  • Sulphite solutions or bisulphite solutions can, for example, be used as the sulphite source in addition to SO2 •
  • Another possibility is to utilize sulphur-containing process stream from a plant for gasification and combustion of black liquor, for example a so-called Chemrec reactor (see SE-C-448 173) as the sulphur source.
  • Yet another possibility is to generate sulphur dioxide internally by burning sulphur gases, which have been driven off from black liquor, to, in the main, sulphur dioxide. This sulphur dioxide can then be absorbed in bleaching-plant liquid which is then used in the sulphite stage or, alternatively, as acidifier, for example in connection with a complex-forming stage.
  • Anthraquinone is also expediently utilized in the sulphite stages in order to improve bleaching selec ⁇ tivity still further.
  • Addition of sodium borohydride represents another option for increasing the reducing capability of the sulphite solution.
  • a sulphite stage which is only acidic and reducing, without being pressurized, and is consequently not significantly sulphonating, is designated (AR) .
  • the equipment for carrying out the bleaching sequence according to the invention expediently consists of a combination of pressurized reactors with intervening pressure diffusers for washing.
  • partial degasification can be required after one or more pressurized stages, for example after a (PO) stage, to enable satisfactory washing to take place in a subsequent diffuser.
  • PO pressurized stage
  • it is previously known from WO 92/07139 to carry out a reducing stage of the sulphite or bisulphite type between two peroxide stages the first peroxide stage in this case is acidic and it is only the second which is alkaline. Further- more, the sulphite stage is not carried out under sulphonating conditions.
  • SE 461 991 discloses a method of improving subsequent oxygen-delignification by means of alkaline sulphite treatment. This sulphite treatment thus has another purpose and is furthermore not carried out under conditions which are to any appreciable extent sulphonating.
  • Q(PO) (PO) elimination of transition metals followed by two pressurized peroxide stages, entirely in accordance with known technique (SE 9301960) . The pulp was washed between the three given stages .
  • Q(PO) (AR) (PO) as in 1, but with an acidic S0 2 stage at 90°C and atmospheric pressure between the two pressurized (PO) stages, that is similarly to EP 433 138. The pulp was washed between the four given stages.
  • Q(PO) (AR*) (PO) a preferred bleaching sequence in accordance with the invention, which sequence is carried out in the same way as for experiment 2 but with the conditions for the sulphite treatment having been chosen so that residual lignin is sulphonated, that is pressure elevated to 6 bar (absolute) and a temperature of 105°C. The pulp was washed between the four stages.
  • the two initial stages Q(PO) were common to the three experimental sequences.
  • the Q stage was carried out in accordance with the LIGNOX procedure (SE 8902058) .
  • H2SO4 was used in the laboratory experiment for acidifying in the complex-forming stage.
  • sulphur dioxide or returned H + ions liberated in association with sulphonating reactions in subsequent stages, for acidifying incoming pulp.
  • the acidifi ⁇ cation stage can be carried out without complex-forming agents. Table 1
  • the sulphonating bleaching according to the invention not only reduces the peroxide consumption by about 10 kg of H2O2 per ton of pulp but also decreases the loss of brightness due to aging and also decreases the content of residual lignin to less than half after full bleaching.
  • the sequence 3b is the same as 3a except that the sulphonation has been carried out somewhat more vigorously and at a lower pH. This experiment demonstrates that very high brightnesses (90.0 ISO) can be achieved using the method according to the invention.
  • the degree of sulphonation affects the quality properties of the bleached pulp in a decisive manner and makes the pulp comparable with chlorine-free pulp produced using ozone or a peroxy acid (peracetic acid, persulphuric acid) .
  • Diagram 1 demonstrates that 16 - 24 kg of SO2 consumed per ton of pulp saves approximately 10 kg of hydrogen peroxide as compared with the reference bleached only with alkaline hydrogen peroxide.
  • the sulphonating sequences according to the invention by large give the same result as the peracetic acid sequence.
  • Comparison of the sulphonating sequence and the ozone sequence shows that about 10 kg of peroxide are required in order to replace 4 kg of ozone.
  • Diagrams 3 and 4 show that the peracetic acid sequences and sulphonating sequences give approximately the same result as far as colour reversion is concerned and that this result is superior to that for the ozone sequence.
  • Diagram 5 show the effect on viscosity versus kappa number when using a sulphonating stage in connection with an oxygen delignification stage.
  • the beneficiary effect of preceeding an oxygen stage with a complex-forming stage is previously known. It has now been found that when replacing the complex-forming stage with a sulphonating stage, even lower kappa numbers can be reached, with acceptable viscosity. If an additional sulphonating stage is added after the oxygen stage, the kappa number can be even more lowered.
  • Sulphonating sequence - charge SO2 10 kg ptp, consumption SO2 : 4 kg ptp, consumption H2O2 : 21 kg ptp.
  • the sulphonating sequence gives yield and strength properties similar to those of the ECF sequence and better than those of the ozone sequence.

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

Abstract

Procédé de blanchiment de pâte à papier chimique, n'utilisant de préférence pas de chlore, dans une séquence de blanchiment comprenant au moins une étape de blanchiment réducteur acide contenant un sulfite et au moins une étape de blanchiment oxydant alcalin, dans un ordre quelconque. Au moins l'une de ces étapes de blanchiment acides contenant un sulfite s'effectue dans des conditions qui sont principalement de sulfonation à un degré de sulfonation supérieur à 10 %, de préférence supérieur à 20 %, et idéalement compris entre 40 et 80 %.
PCT/SE1995/000486 1994-08-16 1995-05-04 Blanchiment de pate a papier chimique dans des conditions de sulfonation WO1996005364A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU27558/95A AU2755895A (en) 1994-08-16 1995-05-04 Bleaching of chemical paper pulp under sulphonating conditions
FI970519A FI970519A0 (fi) 1994-08-16 1997-02-07 Kemiallisen paperimassan valkaisu sulfonoivissa olosuhteissa

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9402726A SE9402726L (sv) 1994-08-16 1994-08-16 Bleksekvens för kemisk massa innefattande ett sulfonerande bleksteg
SE9402726-5 1994-08-16

Publications (1)

Publication Number Publication Date
WO1996005364A1 true WO1996005364A1 (fr) 1996-02-22

Family

ID=20394928

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1995/000486 WO1996005364A1 (fr) 1994-08-16 1995-05-04 Blanchiment de pate a papier chimique dans des conditions de sulfonation

Country Status (6)

Country Link
AU (1) AU2755895A (fr)
CA (1) CA2194290A1 (fr)
FI (1) FI970519A0 (fr)
SE (1) SE9402726L (fr)
WO (1) WO1996005364A1 (fr)
ZA (1) ZA955971B (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998031872A1 (fr) * 1997-01-21 1998-07-23 University Of New Brunswick Procede de delignification a l'oxygene de pate a papier
US6306253B2 (en) 1995-10-20 2001-10-23 Andritz-Ahlstrom Oy Acid treatment of pulp at high temperature prior to chlorine dioxide bleaching
US8980051B2 (en) * 2009-04-24 2015-03-17 International Paper Company Sulfonation of pulp produced by alkali pulping process

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE516219C2 (sv) * 1995-10-26 2001-12-03 Kvaerner Pulping Tech Blekning av kemisk pappersmassa i ett sulfonerande steg och ett surt syredelignifieringssteg

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4560437A (en) * 1983-06-29 1985-12-24 M. Peterson & Son A/S Process for delignification of chemical wood pulp using sodium sulphite or bisulphite prior to oxygen-alkali treatment
EP0433138A1 (fr) * 1989-12-11 1991-06-19 La Cellulose Du Pin Procédé de blanchiment de pâtes cellulosiques chimiques
US5089089A (en) * 1984-12-31 1992-02-18 Bear Island Paper Company System for sulfonating mechanical pulp fibers
WO1992007139A1 (fr) * 1990-10-17 1992-04-30 Interox International S.A. Procede pour la preservation des caracteristiques de resistance mecanique des pates a papier chimiques

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4560437A (en) * 1983-06-29 1985-12-24 M. Peterson & Son A/S Process for delignification of chemical wood pulp using sodium sulphite or bisulphite prior to oxygen-alkali treatment
US5089089A (en) * 1984-12-31 1992-02-18 Bear Island Paper Company System for sulfonating mechanical pulp fibers
EP0433138A1 (fr) * 1989-12-11 1991-06-19 La Cellulose Du Pin Procédé de blanchiment de pâtes cellulosiques chimiques
WO1992007139A1 (fr) * 1990-10-17 1992-04-30 Interox International S.A. Procede pour la preservation des caracteristiques de resistance mecanique des pates a papier chimiques

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6306253B2 (en) 1995-10-20 2001-10-23 Andritz-Ahlstrom Oy Acid treatment of pulp at high temperature prior to chlorine dioxide bleaching
WO1998031872A1 (fr) * 1997-01-21 1998-07-23 University Of New Brunswick Procede de delignification a l'oxygene de pate a papier
US8980051B2 (en) * 2009-04-24 2015-03-17 International Paper Company Sulfonation of pulp produced by alkali pulping process

Also Published As

Publication number Publication date
CA2194290A1 (fr) 1996-02-22
SE9402726D0 (sv) 1994-08-16
AU2755895A (en) 1996-03-07
FI970519A (fi) 1997-02-07
ZA955971B (en) 1996-02-21
SE502135C2 (sv) 1995-08-28
SE9402726L (sv) 1995-08-28
FI970519A0 (fi) 1997-02-07

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