WO1997017489A1 - Procede de delignification a l'oxygene - Google Patents

Procede de delignification a l'oxygene Download PDF

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Publication number
WO1997017489A1
WO1997017489A1 PCT/SE1995/001335 SE9501335W WO9717489A1 WO 1997017489 A1 WO1997017489 A1 WO 1997017489A1 SE 9501335 W SE9501335 W SE 9501335W WO 9717489 A1 WO9717489 A1 WO 9717489A1
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WO
WIPO (PCT)
Prior art keywords
oxygen
pulp
gas
delignification
bars
Prior art date
Application number
PCT/SE1995/001335
Other languages
English (en)
Inventor
Klas Norborg
Christer SJÖLIN
Brita Swan
Original Assignee
Stora Kopparbergs Bergslags 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
Priority to SE9401628A priority Critical patent/SE9401628L/
Application filed by Stora Kopparbergs Bergslags Ab filed Critical Stora Kopparbergs Bergslags Ab
Priority to PCT/SE1995/001335 priority patent/WO1997017489A1/fr
Priority to AU43193/96A priority patent/AU4319396A/en
Publication of WO1997017489A1 publication Critical patent/WO1997017489A1/fr

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

Definitions

  • the present invention relates to a method for the oxygen-gas delignification of chemical pulp. More specifically, the invention relates to the oxygen-gas delignification of chemical pulp at high oxygen-gas pressures.
  • Oxygen-gas delignification is one of the methods used within the pulp industry to remove lignin from the pulp prior to the final bleaching stage.
  • the method has increased in significance, because the soluble substances that are formed in the oxygen-gas delignification process are returned and burned and therewith do not result in toxic secondary products in the waste water from the bleaching department .
  • the interest in oxygen-gas delig ⁇ nification has led to comprehensive studies in research laboratories around the world. However, there is still a desire to achieve improved process performances.
  • Oxygen-gas delignification of chemical pulp is typically carried out on an industrial scale at a pres ⁇ sure of about 5 bars.
  • the pressure is normally restricted to 5-10 bars in laboratory work. This also applies to work in which the influence of the pressure on the delig ⁇ nification process has been studied per se . Those experi- merits that have been reported in the literature give no indication that a pressure above 10 bars would afford any advantage.
  • L. 01m, A. Teder, TAPPI 1979 Pulping Confe ⁇ rence, Seattle, pp. 169-179 has studied the kinetics of oxygen-gas delignification, one of the variables being the partial pressure of oxygen-gas. The effect of the oxygen-gas pressure on the rate of delignification and on selectivity has been examined.
  • Selectivity is a measure ⁇ ment of viscosity decrease per decrease in kappa number.
  • the boundary viscosity of the pulp is a measurement of the degree of polymerization of the cellulose and thus provides an indication of pulp quality. It was found that the delignification rate increased when the oxygen-gas pressure increased from 1 to 10 bars. However, the greatest increase was observed at the lower pressures, between 1 and 5 bars, and the increase progressively tapered off at pressures from 5 bars up to 10 bars. Extrapolation of these results indicates that no appreci ⁇ able increase in the rate of delignification can be expected at oxygen-gas pressures above 10 bars. With regard to selectivity, L. 01m, A. Teder found that the oxygen-gas pressure had no effect at all.
  • the present invention thus provides an improved method for the oxygen-gas delignification of chemical pulp, in which oxygen-gas delignification is effected at oxygen- gas pressures above 10 bars.
  • the oxygen-gas delignifi- cation is effected at oxygen-gas pressures ranging from 15 bars, most preferably between 15-20 bars. It is un ⁇ necessary to define an upper limit for the oxygen-gas pressure, since the method will function well at still higher pressures. The upper limit is governed rather for reasons of a process-technical and economical nature.
  • hydrogen peroxide can be used in the oxygen-gas delignification process. It can be assumed to be highly probable that the good effect afforded by the invention will also be obtained when using other delignification techniques after the cook. There can be mentioned by way of example hydrogen peroxide, peracetic acid, Caros acid, different enzymes (xylanases, mannana- ses, laccases, peroxidases) and chlorine dioxide.
  • chemical pulp is preferably meant sulphate pulp, soda pulp, sulphite pulp and organosol pulps or pulps deriving from other solvent-based cooking methods.
  • oxygen-gas delig- nification of the chemical pulp is carried out in the presence of sodium hydroxide at controlled conditions with respect to pulp consistency, treatment times, treat ⁇ ment temperature and final-pH.
  • Conventional conditions are applied when carrying out the present invention, with the exception of the high oxygen-gas pressure.
  • the inventive method is carried out conveniently at a pulp consistency of 5-50%, preferably 8-15%.
  • the temperature is controlled to levels between 70-130°C, preferably 90- 110°C.
  • the treatment time may vary from fifteen minutes to three hours, although a preferred treatment time is between thirty minutes to ninety minutes.
  • the amount of causttic liquor or alkali introduced to the system may also vary within wide limits, depending on pulp type differences, cooking conditions, etc.
  • the amount of liquor charged may vary from 5-50 kg/ton, preferably 10- 25 kg/ton.
  • the final pH of the pulp is normally control- led to lie between 8-12, preferably 10-11.
  • magnesium sulfate is often also added to the pulp, in addition to alkali.
  • the magne ⁇ sium sulfate is conveniently added in an amount corre ⁇ sponding to 0-10 kg/ton, preferably 2-5 kg/ton.
  • the pulp is then subjected to oxygen-gas delignification in accordance with the invention, as described above.
  • the method can also be applied with pulp that has previously been treated with a chelating agent in at least one position in the process, for instance a pulp that has been treated in solely one Q-stage without being oxygen-gas deligni fied previous thereto.
  • the pulp is treated with oxygen-gas and peroxide at high pressure subsequent to the Q-treatment.
  • Two different non-bleached softwood sulfate pulps were used in the tests.
  • One pulp had a kappa number of 29.3 and a viscosity of 1220 dm 3 /kg, and the other had a kappa number of 15.8 and a viscosity of 1095 dm 3 /kg.
  • the pulps were placed in plastic bags and chela ⁇ ting agent (EDTA) and sulphur dioxide (S0 2 ) were admixed with the pulp at a 10% pulp consistency. The pulps were removed after 60 minutes at a temperature of 70°C and the final-pH determined. The pulps were washed.
  • EDTA chela ⁇ ting agent
  • S0 2 sulphur dioxide
  • the pulp was delignified with ozone after treating the pulp with the chelating agent.
  • the pulp was placed in a titanium mixer for laboratory use. The pulp was fluidized with the aid of a rapidly rotating turbine, whereafter ozone was metered quickly from a pressure vessel. After a fluidizing period of twenty seconds, the pulp was allowed to lie for five minutes with no mixing. The pulp was removed, the final pH determined and the pulp washed at a pH of about 7. Finally, there was used a softwood sulfate pulp which had been delignified in two previous oxygen-gas stages and thereafter treated with a chelating agent (EDTA) and sulphur dioxide. The pulp had a kappa number of 9.0 and a viscosity of 895 dm 3 /kg.
  • EDTA chelating agent
  • the oxygen-gas delignification process was carried out in the same way as that described above with reference to non-bleached sulfate pulps.
  • the bleaching conditions for the different tests are shown below in Table 1, where Q-stage (chelating agent) and Z-stage (ozone) were only applied in certain tests (see result Tables)
  • 0-stage Q-stage Z-stage (OP-stage) (oxygen (chelating (ozone) (oxygen gas) agent) gas/per ⁇ oxide)
  • the bleaching time required to obtain the same degree of delignification with a given quantity of alkali (15 kg/ton) at the 20-bar pressure was only about half the bleaching time required at the 7-bar pressure.

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

Abstract

L'invention porte sur un procédé de délignification à l'oxygène gazeux de pâtes chimiques dans le cadre duquel le processus de délignification à l'oxygène gazeux se déroule sous une pression supérieure à 10 bars. Selon un mode préféré de réalisation, cette opération se déroule sous une pression d'oxygène gazeux commençant à 15 bars et comprise, de préférence, entre 15 et 20 bars. On effectue cette délignification à l'oxygène gazeux sur une pâte non blanchie ou sur une pâte ayant été soumise, dans un premier temps, à une délignification à l'oxygène gazeux et, éventuellement, à l'ozone. La pâte peut également avoir été traitée au moyen d'un agent chélateur dans une étape, au moins, du processus.
PCT/SE1995/001335 1994-05-10 1995-11-09 Procede de delignification a l'oxygene WO1997017489A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
SE9401628A SE9401628L (sv) 1994-05-10 1994-05-10 Förfarande vid syrgasdelignifiering
PCT/SE1995/001335 WO1997017489A1 (fr) 1994-05-10 1995-11-09 Procede de delignification a l'oxygene
AU43193/96A AU4319396A (en) 1995-11-09 1995-11-09 Process for oxygen delignification

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9401628A SE9401628L (sv) 1994-05-10 1994-05-10 Förfarande vid syrgasdelignifiering
PCT/SE1995/001335 WO1997017489A1 (fr) 1994-05-10 1995-11-09 Procede de delignification a l'oxygene

Publications (1)

Publication Number Publication Date
WO1997017489A1 true WO1997017489A1 (fr) 1997-05-15

Family

ID=26662052

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1995/001335 WO1997017489A1 (fr) 1994-05-10 1995-11-09 Procede de delignification a l'oxygene

Country Status (2)

Country Link
SE (1) SE9401628L (fr)
WO (1) WO1997017489A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2391011A (en) * 2002-07-19 2004-01-28 Crosmill Ltd Bleaching cellulose suspensions
WO2006071163A1 (fr) * 2004-12-30 2006-07-06 Kvaerner Pulping Ab Procede de delignification a l'oxygene de la pate a papier par melange de substances chimiques
WO2006071165A1 (fr) * 2004-12-30 2006-07-06 Kvaerner Pulping Ab Procede de delignification a l'oxygene de pate de cellulose sous haute pression en plusieurs etapes
WO2006071164A1 (fr) * 2004-12-30 2006-07-06 Kvaerner Pulping Ab Technique de pompage de la pate a papier

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE335053B (fr) * 1969-05-13 1971-05-10 Mo Och Domsjoe Ab
CA897361A (en) * 1969-12-19 1972-04-11 E. Mallett Samuel Oxygen bleaching process
US3725194A (en) * 1967-06-20 1973-04-03 South Africa Pulp And Paper In Treatment of alkaline pulp with an acidic medium followed by oxygen bleaching and delignification
EP0386888A2 (fr) * 1989-02-10 1990-09-12 ICI Canada Inc. Délignification à l'oxygène et traitement enzymatique
US5091054A (en) * 1989-08-18 1992-02-25 Degussa Corporation Process for bleaching and delignification of lignocellulosic

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3725194A (en) * 1967-06-20 1973-04-03 South Africa Pulp And Paper In Treatment of alkaline pulp with an acidic medium followed by oxygen bleaching and delignification
SE335053B (fr) * 1969-05-13 1971-05-10 Mo Och Domsjoe Ab
CA897361A (en) * 1969-12-19 1972-04-11 E. Mallett Samuel Oxygen bleaching process
EP0386888A2 (fr) * 1989-02-10 1990-09-12 ICI Canada Inc. Délignification à l'oxygène et traitement enzymatique
US5091054A (en) * 1989-08-18 1992-02-25 Degussa Corporation Process for bleaching and delignification of lignocellulosic

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2391011A (en) * 2002-07-19 2004-01-28 Crosmill Ltd Bleaching cellulose suspensions
WO2006071163A1 (fr) * 2004-12-30 2006-07-06 Kvaerner Pulping Ab Procede de delignification a l'oxygene de la pate a papier par melange de substances chimiques
WO2006071165A1 (fr) * 2004-12-30 2006-07-06 Kvaerner Pulping Ab Procede de delignification a l'oxygene de pate de cellulose sous haute pression en plusieurs etapes
WO2006071164A1 (fr) * 2004-12-30 2006-07-06 Kvaerner Pulping Ab Technique de pompage de la pate a papier
EP1834034A1 (fr) * 2004-12-30 2007-09-19 Kvaerner Pulping AB Procede de delignification a l'oxygene de la pate a papier par melange de substances chimiques
EP1834034A4 (fr) * 2004-12-30 2012-12-19 Kvaerner Pulping Tech Procede de delignification a l'oxygene de la pate a papier par melange de substances chimiques

Also Published As

Publication number Publication date
SE9401628L (sv) 1995-11-11
SE9401628D0 (sv) 1994-05-10

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