EP0250422B1 - Verfahren zur herstellung gebleichter pulpe aus lignocelluloserohstoff - Google Patents

Verfahren zur herstellung gebleichter pulpe aus lignocelluloserohstoff Download PDF

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Publication number
EP0250422B1
EP0250422B1 EP86901881A EP86901881A EP0250422B1 EP 0250422 B1 EP0250422 B1 EP 0250422B1 EP 86901881 A EP86901881 A EP 86901881A EP 86901881 A EP86901881 A EP 86901881A EP 0250422 B1 EP0250422 B1 EP 0250422B1
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Prior art keywords
stage
acid
pulp
hydrogen peroxide
raw material
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French (fr)
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EP0250422A1 (de
Inventor
Lauri Aukusti Laamanen
Jorma Juhani Sundquist
Ilkka Yrjö Paavo WARTIOVAARA
Seppo Veli-Matti KAULIOMÄKI
Kristiina Johanna Poppius
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OY KESKUSLABORATORIO - CENTRALLABORATORIUM AB
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KESKUSLABORATORIO - CENTRALLABORATORIUM Oy AB
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Priority to AT86901881T priority Critical patent/ATE53613T1/de
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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
    • D21C9/10—Bleaching ; Apparatus therefor
    • D21C9/16—Bleaching ; Apparatus therefor with per compounds
    • D21C9/163—Bleaching ; Apparatus therefor with per compounds with peroxides
    • 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
    • D21C3/00—Pulping cellulose-containing materials
    • D21C3/003—Pulping cellulose-containing materials with organic compounds

Definitions

  • the present invention relates to a process for preparing bleached pulp from lignocellulosic raw material.
  • the raw material is first treated with a cooking liquor containing oxidizing components, to form a pulp, whereinafter the pulp is bleached.
  • Non-polluting pulping has been aimed at by using closed processes. Furthermore, there have been efforts to find chemicals, the use of which is accompanied by a diminished adverse environmental influence, when compared with conventional pulping chemicals, and which would allow the process to be closed even better.
  • the closing of the process of the second stage of pulping, i.e. bleaching, is difficult.
  • the present bleaching processes are mainly based on the use of chlorine and compounds thereof, but 100% recirculation of bleaching waste-liquors containing chlorine compounds in the process has proved to be very difficult mainly due to corrosion problems.
  • the various detrimental chlorine compounds formed during bleaching are therefore, to rather a large extent, emitted to the environment.
  • Pulping which causes a minimum of environmental pollution is best reached when the chemicals used therein contain only carbon, hydrogen, and oxygen. Many of the new methods tested do not, however, fulfil this requirement; they may contain e.g. nitrogen which is an unpredictable element when considering its environmental influence. It may even prove to be very troublesome.
  • the first stage of pulping i.e. cooking, using chemicals containing carbon, hydrogen, and oxygen only, has mainly been investigated in the connection with so-called organosolv pulping methods.
  • Said methods are based on the use of organic solvents. These usually contain some compound which is called a catalyst, which enhances the degradation of lignin and the conversion thereof into a dissolving form.
  • the drawback of the organosolv-methods lies in their relatively low delignification capacity and the difficulty of pulping softwood.
  • the catalysts often times contain undesirable elements, such as chlorine or sulphur. This makes the non-polluting character of the method questionable when larger amounts of catalysts are employed.
  • lignin-oxidizing chemical e.g. hydrogen peroxide
  • lignin-oxidizing chemical e.g. hydrogen peroxide
  • lignin-oxidizing chemical e.g. hydrogen peroxide
  • a process for pulping wood particles with peracetic acid having a concentration of between about 10 and 40% by weight is anticipated by US Patent Specification No. 2 939 813.
  • the use of a mixture of carboxylic acid/peroxide in the preparation of paper and paperboard pulp has further been disclosed in the SU Patent Specification No. 761647 published in 1980. According to said patent, cooking is carried out at normal pressure at a temperature below 100°C. No data as to the species of wood nor to the bleaching of the pulp are given.
  • the lignin separated and reacted due to the action of the peracetic acid formed in the liquor is removed from the pulp during the second stage of the pulping by means of a dilute alkali solution. According to the publication, the yield is from 75,6% to 86,0%.
  • Chlorine-free bleaching methods are known per se. Thus, during the recent years great expectations have been focused on ozone bleaching employing as its main bleaching chemical an ozone containing gas dissolved in a suitable medium. Hydrogen peroxide has been used in the bleaching of cotton, linen and wool based textiles for a long time. It has also to some extent been used in the bleaching of mechanical pulp and for the bleaching of pulp from sulphite and sulphate processes. In the mentioned applications, it has not been used to any larger extent, since it is not possible to obtain as high a brightness or viscosity as in multistage chlorine bleaching. Said methods are exemplified by the solution mentioned in the US Patent Specification No. 4 400 237.
  • Said publication discloses a bleaching process in two stages for bleaching of sulphite pulp, in the first stage of which hydrogen peroxide (0,2-3,0% by weight) and peracid prepared from an organic carboxylic acid (0,1 - 5,0% by weight) is employed, and in the second stage of which an alkaline peroxide treatment is conducted by adding aqueous alkali to the liquor obtained from the first stage.
  • One object of the present invention is to offset the drawbacks associated with the known pulping and bleaching processes and to provide an entirely novel process for preparing pulp directly from a lignocellulosic raw material essentially in two stages.
  • the invention is based upon using in a first stage a pulping liquor containing peroxyacids derived from carboxylic acids and subsequently treating the defibrated pulp thus obtained with an alkaline solution of hydrogen peroxide in a second stage.
  • the process in accordance with the present invention comprises the combination of
  • the liquor employed in the first stage containing peroxyacids is preferably provided by the addition of hydrogen peroxide to an organic carboxylic acid, e.g. formic, acetic, propionic, or butyric acid.
  • an organic carboxylic acid e.g. formic, acetic, propionic, or butyric acid.
  • the process according to the invention forms, in spite of the provision of two stages, an integrated delignification system, the stages of which function synergistically.
  • an integrated delignification system the stages of which function synergistically.
  • the brightness of the pulp in accordance with the present invention is about twice as high as that of the unbleached kraft pulp after treatment with an alkaline peroxide solution.
  • the apparatus required by the process is simple.
  • the acid stage as well as the alkaline stage may be conducted at normal pressure, since there is no need for raising the reaction temperatures above the boiling point of the mixture.
  • the low temperatures result in huge savings in energy consumption.
  • the present delignification process in two stages may be used for the delignification of all kinds of lignocellulosic materials. It is particulary well suited for chips of hardwood and softwood commonly employed in pulping. Delignification of hardwood proceeds somewhat better than that of spruce and pine chips. Annual plants, grass, straw and bagasse may also be used as raw materials.
  • the first stage of the process i.e. the peroxyacid stage, is preferably conducted by using a mixture of some liquid carboxylic acid and hydrogen peroxide.
  • carboxylic acids due to the influence of hydrogen peroxide, the carboxylic acids are oxidized to peroxyacids which form the active agents of the cooking liquor.
  • the peroxyacid reacts with lignin, and the oxidization products formed from this reaction dissolve in the solution of carboxylic acids.
  • the various carboxylic acids have a different capability of forming peroxyacids, i.e. their oxidative capacity differs. In principle, no carboxylic acid may be excluded from the process. Aliphatic as well as aromatic acids are suitable. In practice, formic and acetic acids are particulary preferred, of which the first mentioned acid more easily forms peroxyacid, and it is therefore in this sense preferred.
  • the pulp obtained when using formic acid in the first stage is darker than that obtained by using acetic acid, on the other hand, the viscosity of the pulp is lower when the last- mentioned acid has been employed.
  • propionic and butyric acids may also be used.
  • peroxyacids may be enhanced by using some known catalysts, e.g. sulphuric, phosphoric or boric acids, but this is neither necessary nor always even preferable. It has been discovered that, e.g., sulphuric acid may degrade the carbohydrates during the cooking, which leads to a decreased viscosity of the pulp.
  • catalysts e.g. sulphuric, phosphoric or boric acids
  • the concentration of the carboxylic acid employed is in the range of 40...100%, preferably in the range of 70...100%, the liquid-to-wood ratio being from 2:1 up to 10:1.
  • the ratio 8:1 normally used in pulping may be used.
  • a smaller liquid ratio e.g. 4:1, because said ratio makes it possible to decrease the required amount of hydrogen peroxide and enhance the progress of the delignification reaction. Pulp yield and brightness of the pulp are also improved by a smaller liquid-to-wood ratio.
  • the peroxyacids may be formed in the solution in some other known manner, e.g. by reacting the corresponding aldehydes with molecular oxygen or an oxygen-ozone mixture.
  • the carboxylic acids needed for the dissolution of the reaction products are formed as decomposition products of the peroxyacids.
  • the peroxyacids may also be formed in the cooking liquor prior to the addition of the cellulosic raw material.
  • the peroxide used may comprise, e.g., an industrially prepared hydrogen peroxide solution, the concentration of which is 50%.
  • concentration of the peroxide may, however, be higher or lower, i.e. from about 30% up to 90% by weight.
  • the amount used varies within a large range depending on the extent to which the delignification is to be conducted during the acid stage. It is preferable to achieve a defibration of the chips before the second stage.
  • the amount of peroxide used in the examples has been varied from 5% up to 60% based on the oven dry (o.d.) weight of the chips, but said values are not absolute limits.
  • Water present in the carboxylic acid, in the peroxide as well as in the chips, is introduced into the cooking liquor.
  • the water content of the acid influences especially the dissolution of the oxidized lignin. Thus, it should be kept as low as possible.
  • the acid peroxy-treatment may be conducted at any temperature between ambient temperature and the boiling point of the system used.
  • high temperatures are not suitable due to the fact that the peroxyacids decompose when the temperature is raised, whereby the delignification capacity of the cooking liquor is lost.
  • the oxidizing capacity of a pure formic acid/ peroxide mixture disappears altogether within an hour when the temperature is 80°C.
  • the oxidizing capacity of the mixture of acetic acid and peroxide is conserved rather a long time even at 95°C, but this is due to the fact that the rate of peroxyacid formation is slower for acetic acid than for formic acid.
  • the cooking temperature to be selected depends on the acid used.
  • the temperature is preferably in the range of about 70° - 90°C, and for acetic acid somewhat higher.
  • For propionic and butyric acids still higher temperatures may be used.
  • the cooking liquor is heated for some time at a higher temperature, e.g. at about 90°C, whereupon the actual cooking is conducted at a lower temperature of, e.g., from 70°C up to 75°C.
  • Cooking time may also vary within a large range depending on the temperature. At ambient temperature the treatment lasts for several days, whereas it may be as short as one-half an hour when conducted near to the boiling point of water. Too long a treatment time at high temperature lowers the viscosity of the pulp.
  • the acid used and the cooking temperature the cooking time is from 2 hours up to 10 hours, preferably from 4 hours up to 6 hours.
  • the impregnation may be conducted at ambient temperature. It has been discovered that a delig- nifying pretreatment of the chips decreases considerably the amount of hydrogen peroxide needed in the peroxyacid treatment stage, thus reducing the actual cooking time. This is true especially for birch raw material.
  • the pretreatment may be conducted at ambient temperature or preferably at an increased temperature by means of some chemical, e.g. an alkali solution or preferably formic acid as taught by the SU Patent Specification No. 821614.
  • the acid treatment is carried out, e.g., at the boiling point of the acid, whereat prolonging of the pretreatment time lowers the kappa number.
  • the pretreatment acid spent peroxyacid cooking liquor may be used.
  • the alkali solution used may be the same as in the second phase of the process. By means of the alkali treatment it is possible to reach an extremely high brightness.
  • a preferred embodiment of the first stage of the invention comprises pulping the chips first in peroxyformic acid, thereafter in formic acid and subsequently again in peroxyformic acid. Delignified pulp (kappa number on the order of 10) is easily obtained by said procedure. Peroxyacetic acid pulping may also be conducted in a similar manner.
  • the defibrated pulp is preferably washed with water such that the pulp obtained is at least approximately neutral.
  • the acid of the spent liquor obtained from this phase may be re-used after recovery.
  • the acid is separated from the solid substance, e.g., by means of distillation.
  • Formic acid and water form an azeotropic mixture which boils already at 107°C. This azeotropic mixture contains about 80% of formic acid and may be re-used as such.
  • the second phase of the present pulping process may be conducted by using a water-soluble alkali and hydrogen peroxide.
  • the amount of the alkali depends on the amount consumed during the treatment.
  • the pH value of the treatment liquor shall initially exceed 10, the required amount being dependent upon the amount required for reaching said pH level. It has been ascertained that acceptable results are reached already at pH values slightly in excess of 10. Higher pH values may of course also be employed, but when it comes to the bleaching result or the economy of the chemicals, it is not sensible to increase the alkalinity to a high level. It has been further ascertained that the amounts of alkali and hydrogen peroxide are somewhat interdependent. The more hydrogen peroxide is used, the more alkali is needed. During the treatment the pH of the liquor decreases to some extent, usually about one pH unit.
  • the alkaline peroxide phase may also be accomplished such that the calculated amount of peroxide is used in several portions, e.g. in 3 to 6 portions.
  • the bleaching liquor is removed from the pulp after each phase.
  • the pulp is preferably washed between the phases of treatment, but if the bleaching is conducted as a so-called displacement bleaching, this is not necessary.
  • a multiphase bleaching has been discovered to have a preferable influence on the brightness of the pulp. The viscosity of the pulp remains high at the same time.
  • the alkali used may be selected from the group consisting of alkali metal and earth alkali metal hydroxides, carbonates and bicarbonates. Alkali metal hydroxides and carbonates are preferred, particulary preferred are sodium hydroxide and sodium carbonate. The alkali may also comprise mixtures of said compounds. It is preferable to use sodium hydroxide because minor amounts result in achieving the required pH value.
  • Sodium carbonate on the other hand is suitable in the sense that it may be obtained by calcination of the spent liquor from the alkali phase. Because the pulp treated in the second phase is almost neutral, no carbon-dioxide is evolved from the carbonate, which might make the treatment more difficult.
  • the temperature of the treatment may vary, but e.g. the common temperature, 80°C, used in the peroxide bleaching of conventional pulps may also be used in this context.
  • the duration of the treatment varies according to the temperature. At 80°C the suitable time is about 1 hour. Generally, a peroxide residue after this stage on the order of 0.2% of the pulp should be the objective.
  • the required amount of peroxide depends on the kappa number, i.e. the lignin content of the pulp coming to said stage. Generally, the amount is from 1% up to 20%. It has been discovered empirically that the added amount of hydrogen calculated as percent of the dry weight of the matter coming to the treatment stage amounts to about 0.20 to 0.80, preferably 0.25 to 0.70, most preferably 0.45 to 0.65 times the kappa number of the pulp from the first phase.
  • the second phase may be accomplished in a different manner also.
  • the alkali and the hydrogen peroxide required may be substituted by a peroxide derivative.
  • a peroxide derivative e.g. a metal peroxide, preferably sodium peroxide, which dissolves in water the form hydroxide and hydrogen peroxide.
  • peroxide stabilizers may be added.
  • citric acid may be used, whereas e.g. diethylene triaminepenta acetic acid (DTPA) or/ and one magnesium salt, e.g. Mg sulfate, may be used during the alkaline peroxide stage.
  • DTPA diethylene triaminepenta acetic acid
  • Mg sulfate magnesium salt
  • the invention will now be examined in more detail by means of the following non-limitative practical examples.
  • the brightness values indicated in the examples have been determined according to the SCAN C-11 method and the viscosity values correspondingly according to the SCAN C-15 method.
  • the kappa numbers have been measured by the SCAN C-1:77 method. All of the indicated per cent amounts are expressed by weight.
  • the initial pH value was 10.3, and it decreased to a value of 9.4 during the treatment.
  • the stabilizing agent comprised 0.2% of DTPA. After the treatment, the pulp was washed and acid was added, whereupon the pulp was dried. The final brightness of the pulp was 89.0%, the viscosity 830 cm 3 /g, and the pulp yield in per cent of the raw material 44.4%.
  • Unbleached spruce kraft pulp the kappa number of which was 31,9, was bleached at 10 per cent stock at 80°C for 30 minutes.
  • the brightness of the pulp thus obtained was 46.5% and the viscosity 750 cm 3 /g.
  • birch chips dry matter 90%
  • the cooking was carried out departing from the foregoing such that the temperature was raised to 70°C during 5 hours, whereinafter the temperature was raised to 80°C within one hour and the cooking was finished.
  • the shives amounted to 3.1%, and the kappa number of the pulp was 5.3.
  • the alkaline hydrogen peroxide treatment was conducted at 80°C, the duration being one hour.
  • the pH of the solution was 10.4.
  • Analysis of the pulp brightness 89.0%, viscosity 1050 cm3 / g.
  • spruce chips dry matter 93%) was used instead of pine.
  • the temperature of the cooking was raised to 80°C within 2.5 hours, and left at said temperature for 2.5 hours.
  • Shives 11.4% and the kappa number of the pulp 14.0.
  • the pH of the solution was 10.8%.
  • Analysis of the pulp brightness 84.3%, viscosity 920 cm 3 /g and pulp yield 43.1% (calculated on the wood).
  • the pine chips was pretreated before the peroxide cooking for one hour at 90°C with 80% formic acid.
  • the cooking was carried out by raising the temperature within 3 hours to 75°C, whereupon the cooking was finished. There were no shives.
  • the kappa number was 7.3.
  • the alkaline hydrogen peroxide treatment was conducted at 80°C, the duration being two hours at 10% stock.
  • the pH of the solution was 10.1. Analysis of the pulp: brightness 86.0%, viscosity 900 cm 3 /g and the pulp yield (calculated on wood) 43.9%.
  • the birch chips were pretreated prior to the peroxide cooking for one hour at 100°C with an alkali solution containing 6% o.d. wood NaOH.
  • the cooking was carried out using the peroxide application rate 20% per o.d. wood.
  • the temperature was raised within 4 hours 20 minutes to 75°C, the cooking being maintained at 75°C to 80°C for 2 hours.
  • the amount of shives was 12.6%, and the kappa number was 14.5.
  • the alkaline peroxide treatment was conducted at 10 per cent stock during 1 hour.
  • the pH of the solution was 10.8.
  • Analysis of the pulp gave: brightness 86.5%, viscosity 1000 cm 3 /g and the pulp yield 43.2% (calculated on the wood).
  • the pulp obtained was bleached with an alkaline solution of hydrogen peroxide such that the calculated amount of hydrogen peroxide, 30.8% of the pulp (16.3% o.d. wood, i.e. 0.60 x the kappa number), was added in three portions.
  • the temperature during all stages was 80°C, the reaction time 1 hour, and the initial pH value 10.5.
  • the stabilizer added comprised 0.2% DTPA.
  • the brightness of the pulp was 90.3.
  • the total consumption of hydrogen peroxide was in this example 10 + 16.3%, i.e. 26.3% of the o.d. chips.
  • the pulp obtained was bleached as described in example 8, the calculated amount of hydrogen peroxide, 28% of the pulp (12.8% o.d. wood, i.e. 0.45 x the kappa number), was also this time added in three portions.
  • the brightness of the pulp was 87.0%.
  • the total consumption of hydrogen peroxide in this example was 5 + 12.8%, i.e. 17.8% of the o.d. chips.
  • the birch chips were pretreated before the peroxyacid cooking by boiling them for 3 hours in 80% formic acid under reflux conditions.
  • the cooking liquor was removed, the peroxyformic acid cooking being subsequently carried out employing 85% formic acid to which 5% hydrogen peroxide of o.d. wood only had been added.
  • the temperature was raised in 50 minutes to 80°C and maintained at said temperature for 1 hour. After the cooking the pulp was washed to neutrality with the required amount of hot water.
  • the kappa number of the pulp was at this stage 14.7 and the viscosity 1180 cm 3 /g and the yield 42.3%.
  • the pulp obtained was bleached with an alkaline solution of hydrogen peroxide such that the calculated amount of hydrogen peroxide, 8% of the pulp (3.4% o.d. wood, i.e. 0.55 x the kappa number), was added in four portions: the duration of the first two stages was 1 hour, the duration of the two last ones was 2 hours. The temperature during all stages was 80°C, and the initial pH value 10.7.
  • the stabilizer added comprised 0.2% DTPA and 0.5% (calculated on o.d. wood) Mg sulfate.
  • the brightness of the pulp obtained was 90.1 %, and the viscosity 1140 cm 3 / 9.
  • the total consumption of hydrogen peroxide was in this example 5 + 3.4%, i.e. 8.4% of the o.d. chips only.
  • the pulp was first washed with formic acid and thereafter with water.
  • the kappa number of the pulp was 9.0, the viscosity 980, the brightness 35.1 and the screened yield 41.4%.
  • the amount of shives was only 0.2%.
  • the pulp obtained was bleached with an alkaline hydrogen peroxide solution such that the calculated amount of hydrogen peroxide, 6% of the pulp (2.5% o.d. wood), was added in three portions.
  • the duration of the first stage was 1 hour, of the second one 2 hours, and of the third one 3 hours.
  • the temperature was 80°C.
  • the stabilizers were analogous to those employed in example 11.
  • the brightness of the pulp obtained was 90.5, and the viscosity 940.
  • the total consumption of hydrogen peroxide was in this example 10 + 2.5%, i.e. 12.5% of the o.d. chips.

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Claims (15)

1. Verfahren zur Herstellung gebleichter Pulpe aus Lignocelluloserohstoff, wobei dieser Rohstoff zur Bildung einer Pulpe zuerst mit einer oxidierende Komponenten enthaltenden Kochflüssigkeit behandelt wird und die Pulpe danach gebleicht wird, das die Kombination umfaßt von
A) Zerfaserung des Lignocelluloserohstoffes mit Hilfe einer Kochflüssigkeit, die ein aktives organisches Mittel enthält, ausgewählt aus der Gruppe Peroxyformylsäure, Peroxyessigsäure, Peroxypropionsäure und Peroxybuttersäure, um eine chemisch zerfaserte Pulpe zu bilden, und
B) Bleichen der zerfaserten Pulpe mit einer alkalischen Lösung, die Wasserstoffperoxid enthält in einer Menge, die prozentual bezogen auf das Trockengewicht des in die Behandlung zugesetzten Rohstoffes von 0,2 - 0,8 mal der Kappa-Zahl der aus der Stufe A des Prozesses kommenden chemisch zerfaserten Pulpe entspricht, bei einem pH-Wert von mindestens 10 in der Anfangsphase des Bleichens, um eine gebleichte, chemisch zerfaserte Pulpe zu erhalten.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Menge des Wasserstoffperoxids in der Stufe B zwischen 0,25 - 0,7 mal der Kappa-Zahl entspricht.
3. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Menge des Wasserstoffperoxids in der Stufe B zwischen 0,45 - 0,65 mal der Kappa-Zahl entspricht.
4. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Kochflüssigkeit, die in der Stufe A benutzt wird, hergestellt wird, indem bezogen auf ofentrockenes Holz mindestens ein Gewichtsprozent Wasserstoffperoxid auf 40 bis 100 Gewichtsprozent von Ameisensäure, Essigsäure, Propionsäure oder Buttersäure zugesetzt wird.
5. Verfahren nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß das Flüssigkeit-zu-Holz-Verhältnis bei einem Wert im Bereich zwischen 2:1 bis 10:1, vorzugsweise im Bereich 4:1 bis 8:1 gehalten wird.
6. Verfahren nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß die Ameisensäure, Essigsäure, Propionsäure oder Buttersäure aus der verbrauchten Flüssigkeit der Stufe A zurückgewonnen und zur Bildung der Kochflüssigkeit wiederverwandt wird.
7. Verfahren nach Anspruch 6, dadurch gekennzeichnet, daß die Ameisensäure als azetrope Mischung von Ameisensäure und Wasser wiedergewonnen wird, mit einer Konzentration von Ameisensäure von etwa 80%, wobei die Wiedergewinnung eine Destillation der in der Stufe A verbrauchten Flüssigkeit umfaßt.
8. Verfahren nach einem der Ansprüche 1 bis 7, dadurch gekennzeichnet, daß das Rohmaterial in der Stufe A mit der Kochflüssigkeit in zwei getrennten Stufen zur Pulpe verarbeitet wird, wobei das Rohmaterial zwischen diesen beiden Stufen mit der korrespondierenden Karbonsäure an deren Siedepunkt behandelt wird.
9. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß das Rohmaterial vor der Stufe A mit einer Karbonsäure, vorzugsweise Ameisensäure oder Essigsäure, vorbehandelt wird, bei einer Temperatur, die der Siedetemperatur der jeweiligen Säure entspricht.
10. Verfahren nach Anspruch 9, dadurch gekennzeichnet, daß das Rohmaterial vor der Stufe A mit der Ameisensäure enthaltenden, verbrauchten Flüssigkeit aus der Stufe A vorbehandelt wird.
11. Verfahren nach einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, daß vor der Stufe A das Rohmaterial mit der wäßrigen, alkalischen Lösung, die in der Stufe B benutzt wurde, bei einer Temperatur von ca. 100°C vorbehandelt wird.
12. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die alkalische Lösung die in der Stufe B benutzt wird, einen Anteil enthält, der aus der Gruppe Natriumhydroxid, Natriumkarbonat und einer Mischung hieraus stammt.
13. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die berechnete Menge von Wasserstoffperoxid in der Stufe B in mehreren Teilen zugesetzt wird, wobei die Bleichlösung nach der Beendigung jeder Stufe entfernt wird, und wonach die gebleichte, chemisch zerfaserte Pulpe optional gewaschen wird.
14. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Temperatur der Kochflüssigkeit der Stufe A anfänglich auf einer Temperatur von ungefähr 100°C gehalten wird, wonach das eigentliche Kochen bei einer Temperatur von 70°C bis 75°C durchgeführt wird.
15. Verfahren nach Anspruch 4, dadurch gekennzeichnet, daß Zitronensäure bei Stufe A zugesetzt wird als Stabilisator für das Wasserstoffperoxid, und Diethylentriaminpentaessigsäure (DTPA) und/oder Magnesiumsulfat bei Stufe B zugesetzt wird als Stabilisator für das Wasserstoffperoxid.
EP86901881A 1985-03-22 1986-03-24 Verfahren zur herstellung gebleichter pulpe aus lignocelluloserohstoff Expired - Lifetime EP0250422B1 (de)

Priority Applications (1)

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AT86901881T ATE53613T1 (de) 1985-03-22 1986-03-24 Verfahren zur herstellung gebleichter pulpe aus lignocelluloserohstoff.

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
FI851156A FI851156A0 (fi) 1985-03-22 1985-03-22 Foerfarande foer framstaellning av blekt cellulosamassa av ligninhaltigt raomaterial.
FI851156 1985-03-22
FI860609A FI74750C (fi) 1985-03-22 1986-02-11 Foerfarande foer framstaellning av blekt cellulosamassa utav ligninhaltigt raomaterial.
FI860609 1986-02-11

Publications (2)

Publication Number Publication Date
EP0250422A1 EP0250422A1 (de) 1988-01-07
EP0250422B1 true EP0250422B1 (de) 1990-06-13

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP86901881A Expired - Lifetime EP0250422B1 (de) 1985-03-22 1986-03-24 Verfahren zur herstellung gebleichter pulpe aus lignocelluloserohstoff

Country Status (6)

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EP (1) EP0250422B1 (de)
JP (1) JPH0737720B2 (de)
AU (1) AU5589286A (de)
DE (1) DE3671924D1 (de)
FI (1) FI74750C (de)
WO (1) WO1986005529A1 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6183597B1 (en) 1995-05-03 2001-02-06 Natural Pulping Ag Method of producing a pulp from cellulosic material using formic acid and hydrogen peroxide
RU2590882C1 (ru) * 2015-04-27 2016-07-10 Федеральное Государственное Бюджетное Учреждение Науки Институт Химии И Химической Технологии Сибирского Отделения Российской Академии Наук (Иххт Со Ран) Способ получения целлюлозы

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FI80191C (fi) * 1988-03-30 1990-05-10 Valio Meijerien Foerfarande och konserveringsmedel foer ensilering av foder.
GB2304126A (en) * 1995-08-10 1997-03-12 Warwick Int Group Pulp treatment process
FI103588B1 (fi) * 1996-01-19 1999-07-30 Esa Rousu Consulting Oy Menetelmä tekokuitujen ja muiden kuitujen raaka-aineen valmistamiseksi ruohovartisista kasveista
FI103899B1 (fi) * 1996-11-06 1999-10-15 Chempolis Oy Menetelmä erityisen vaalean massan valmistamiseksi
FI116390B (fi) 1998-05-05 2005-11-15 Chempolis Oy Menetelmä massan valmistamiseksi
CN100430552C (zh) * 2003-05-29 2008-11-05 中国科学院成都有机化学研究所 一种造纸制浆用蒸煮催化剂
JP5938979B2 (ja) * 2012-03-23 2016-06-22 日本製紙株式会社 植物系原料の処理方法
DE102016219719B3 (de) * 2016-10-11 2018-01-25 Clariant International Ltd. Verfahren zur Gewinnung von Cellulose, Hemicellulose und Lignin aus Lignocellulose aus pflanzlicher Biomasse
CN112778539A (zh) * 2021-01-04 2021-05-11 中国林业科学研究院林产化学工业研究所 一种从纤维原料中制备高羧基含量的氧化木质素的方法

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DE969093C (de) * 1948-11-11 1958-04-30 Aschaffenburger Zellstoffwerke Verfahren zur Herstellung von gebleichtem Zellstoff aus Holz oder anderem pflanzlichem Material
US2939813A (en) * 1956-04-25 1960-06-07 Columbia Cellulose Company Ltd Pulping of lignocellulosic material
US3458394A (en) * 1965-10-08 1969-07-29 Scott Paper Co Pulping wood chips with peracetic acid and chlorine dioxide
JPS5417041A (en) * 1977-07-07 1979-02-08 Mitsubishi Electric Corp Refractive index distribution type lens and production thereof
DE3005947B1 (de) * 1980-02-16 1981-01-29 Degussa Verfahren zur Bleiche von Zellstoffen mittels organischer Persaeure

Non-Patent Citations (1)

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Title
Derwent's abstract no 07598 E/04, SU 821614 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6183597B1 (en) 1995-05-03 2001-02-06 Natural Pulping Ag Method of producing a pulp from cellulosic material using formic acid and hydrogen peroxide
RU2590882C1 (ru) * 2015-04-27 2016-07-10 Федеральное Государственное Бюджетное Учреждение Науки Институт Химии И Химической Технологии Сибирского Отделения Российской Академии Наук (Иххт Со Ран) Способ получения целлюлозы

Also Published As

Publication number Publication date
FI860609A (fi) 1986-09-23
DE3671924D1 (de) 1990-07-19
AU5589286A (en) 1986-10-13
FI860609A0 (fi) 1986-02-11
WO1986005529A1 (en) 1986-09-25
FI74750B (fi) 1987-11-30
JPS62502553A (ja) 1987-10-01
EP0250422A1 (de) 1988-01-07
JPH0737720B2 (ja) 1995-04-26
FI74750C (fi) 1988-03-10

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