SE469842B - Bleaching of chemical pulp with peroxide - Google Patents

Bleaching of chemical pulp with peroxide

Info

Publication number
SE469842B
SE469842B SE9200152A SE9200152A SE469842B SE 469842 B SE469842 B SE 469842B SE 9200152 A SE9200152 A SE 9200152A SE 9200152 A SE9200152 A SE 9200152A SE 469842 B SE469842 B SE 469842B
Authority
SE
Sweden
Prior art keywords
pulp
bleaching
peroxide
ton
complexing agent
Prior art date
Application number
SE9200152A
Other languages
Swedish (sv)
Other versions
SE9200152D0 (en
SE9200152L (en
SE469842C (en
Inventor
L-Aa Lindstroem
L Sjoedin
S Norden
M Dahl
Original Assignee
Sunds Defibrator Ind 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
Family has litigation
First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=20385065&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=SE469842(B) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Application filed by Sunds Defibrator Ind Ab filed Critical Sunds Defibrator Ind Ab
Priority to SE9200152A priority Critical patent/SE469842C/en
Publication of SE9200152D0 publication Critical patent/SE9200152D0/en
Priority to NZ246713A priority patent/NZ246713A/en
Priority to AU34125/93A priority patent/AU653467B2/en
Priority to AT93902618T priority patent/ATE151826T1/en
Priority to ES93902618T priority patent/ES2102008T3/en
Priority to PCT/SE1993/000012 priority patent/WO1993014262A1/en
Priority to JP5512379A priority patent/JPH07503042A/en
Priority to BR9305761A priority patent/BR9305761A/en
Priority to EP93902618A priority patent/EP0621915B1/en
Priority to DE69309893T priority patent/DE69309893T2/en
Priority to CA002124088A priority patent/CA2124088A1/en
Priority to ZA93317A priority patent/ZA93317B/en
Publication of SE9200152L publication Critical patent/SE9200152L/en
Publication of SE469842B publication Critical patent/SE469842B/en
Priority to NO942718A priority patent/NO942718L/en
Priority to FI943431A priority patent/FI943431A0/en
Publication of SE469842C publication Critical patent/SE469842C/en

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
    • D21C9/153—Bleaching ; Apparatus therefor with oxygen or its allotropic modifications with ozone
    • 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
    • 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
    • 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

Landscapes

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

Abstract

A method of bleaching sulphate pulp without using chlorine-containing bleaching agents. The sulphate pulp is oxygen delignified and can possibly also be ozone delignified to a kappa number below 9.5. Thereafter a pretreatment with complexing agent is carried out for 1-60 minutes, at which the pulp consistency is 1-15 %, the temperature 70-110 DEG C and pH 5-7. The pulp thus pretreated is washed and dewatered to a consistency of 18-40 %. Thereafter peroxide bleaching in alkaline environment takes place in the presence of silicate or an organic complexing agent of the type phosphonic or carboxylic acid.

Description

15 20 25 30 35 40 469 842 2 Den enligt ovan kokade och syrgasdelignifierade och eventuelllt ozondelignifierade massan skall ha ett kappatal under 9,5. Detta kan åstadkommas med kända förfaranden för kokning och delignifiering. Massan skall därefter förbehandlas med komplexbildare, exempelvis EDTA eller DTPA, vid en massakonc av 1 - 15% under 1 - 60 min, lämpligen 5 - 30 min. Temperaturen skall vara 70 Ä 100°C, lämpligen 80 - 100°C, och pH-värdet 5 - 7. The mass according to the above boiled and oxygen delignified and possibly ozone delignified mass must have a kappa number below 9.5. This can be accomplished by known methods of boiling and delignification. The pulp should then be pretreated with complexing agents, for example EDTA or DTPA, at a pulp concentration of 1 - 15% for 1 - 60 minutes, preferably 5 - 30 minutes. The temperature should be 70 Å 100 ° C, preferably 80 - 100 ° C, and the pH value 5 - 7.

Den så förbehandlade massan tvättas och awattnas till en koncentration av 18 - 40%, lämpligen 20 - 30%, pH~vârdet höjs till alkalisk nivå och väteperoxid tillsätts tillsammans med silikat, exempelvis natriumsilikat, altemativt tillsammans med en organisk komplexbildare av fosfonsyra- eller karboxylsyratyp. Massans uppehållstid i detta vâteperoxidsteg skall vara 1/2 - 5 timmar, lämpligen 1 - 4 timmar, och temperaturen 70 - 110°C, lämpligen 80 - 100°C. Silikatsatsningen skall vara 2 - 30 kg/ton massa, lämpligen 5 - 15 kg /ton massa, uttryckt som SiOz. Altemativt skall satsningen av den organiska komplexbildaren vara 0,5 - 5 kg/ton massa.The mass thus pretreated is washed and dewatered to a concentration of 18-40%, preferably 20-30%, the pH is raised to alkaline level and hydrogen peroxide is added together with silicate, for example sodium silicate, alternatively together with an organic complexing agent of phosphonic acid or carboxylic acid type. . The residence time of the pulp in this hydrogen peroxide step should be 1/2 - 5 hours, preferably 1 - 4 hours, and the temperature 70 - 110 ° C, preferably 80 - 100 ° C. The silicate charge shall be 2 - 30 kg / ton pulp, preferably 5 - 15 kg / ton pulp, expressed as SiO 2. Alternatively, the charge of the organic complexing agent should be 0.5 - 5 kg / ton of pulp.

Fig 1 visar ett diagram där massans ljushet avsatts som funktion av massakoncentrationen vid peroxidblekningen, dels vid konventionell peroxidblekning och dels vid blekning enligt uppfinningen.Fig. 1 shows a diagram where the brightness of the pulp is plotted as a function of the pulp concentration in the peroxide bleaching, partly in conventional peroxide bleaching and partly in bleaching according to the invention.

Utgângsmassan var oxygendelignifierad barrvedssulfatmassa med kappatal 6,5 (10,5 efter kokningen).The starting mass was oxygen-like coniferous sulphate pulp with a kappa number of 6.5 (10.5 after boiling).

Kurva 1 avser konventionell peroxidblekning med en HzOz-förbrukning av 20 kg/ton massa. Kurva 2 respektive 3 avser blekning enligt uppfinningen med silikattillsats och en HzOz-förbrukning av 20 respektive 30 kg/ton massa.Curve 1 refers to conventional peroxide bleaching with a HzO 2 consumption of 20 kg / ton pulp. Curves 2 and 3, respectively, refer to bleaching according to the invention with silicate additive and an H 2 O 2 consumption of 20 and 30 kg / ton pulp, respectively.

Av diagrammet framgår hur ljusheten, efter blekning enligt uppfinningen respektive efter konventionell blekning, beror av massakoncentrationen. Vid ca 12% massakoncentration erhålls likvärdig ljushet i båda fallen, men vid ökad massakoncentration i peroxídsteget erhålls en ökad ljushet enligt uppfinningen medan konventionell peroxidblekning resulterar i en försämrad ljushet.The diagram shows how the brightness, after bleaching according to the invention and after conventional bleaching, respectively, depends on the pulp concentration. At about 12% pulp concentration, equivalent brightness is obtained in both cases, but at increased pulp concentration in the peroxide step, an increased brightness according to the invention is obtained, while conventional peroxide bleaching results in a reduced brightness.

Följande exempel avser att ytterligare belysa uppfinningen och dess fördelar.The following examples are intended to further illustrate the invention and its advantages.

Exempel 1 En oxygendelignifierad barrsultatmassa (skandinavisk tall/gran) med kappatal 6,4 (10,5 efter kokning enligt ovan nämnda Fl pans 90 0663), ljushet 43% ISO, gränsviskositet 605 dm°/kg, förbehandlades med komplexbildare och peroxidblektes enligt uppfinningen.Example 1 An oxygen-like coniferous pulp (Scandinavian pine / spruce) with kappa number 6.4 (10.5 after boiling according to the above-mentioned Flans 90 0663), brightness 43% ISO, intrinsic viscosity 605 dm ° / kg, pretreated with complexing agent and peroxide bleached according to the invention .

Förbehandling Massakoncentration % 5 Tid min 15 Temperatur °C 90 EDTA kg/ton 2 Slut pH 6,1 Peroxidsteg Massakoncentration % 25 Tid min 240 Temperatur °C 90 SiOa kg/ton 10 HzOa-förbrukning kg/ton 13,5 32,0 slut pH 10,2 10,3 Ljushet % ISO 79,6 84,2 Gränsviskositet dma/kg 520 447 -. 10 15 20 25 30 35 40 45 50 Exempel 2 =l lmsyfifi 469 842 En barrsulfatmassa med kappatal 13,3 (kokad av skandinavisk tall /gran enligt Fl pans 90 0663), oxygendelignifierad till kappatal 8,3 och ozonblekt i sur miljö till kappatal 3,2, ljushet 61% ISO, gränsviskositet 582 dm°/kg, blektes enligt uppfinningen: Förbehandling lika som Exempel 1 Peroxidblekning Massakoncentration % Tid min Temperatur °C SiOz kg/ton HzOz-förbrukning kg/ton 7,3 Slut pH 8,9 Ljushet % ISO 85,3 Gränsviskositet dm°/kg 536 Exempel 3 25 240 10 1 4,2 9,5 88,4 498 30,1 10,1 90,4 420 En oxygendelignifierad barrvedssulfatmassa (kokad av Pinus taeda enligt Fl pans 90 0663) med kappatal 9,9, ozonblekt till kappatal 4,8, ljushet 54,5 % ISO, gränsviskositet 607 dm°/kg förbehandlades och blektes enligt uppfinningen.Pretreatment Mass concentration% 5 Time min 15 Temperature ° C 90 EDTA kg / ton 2 End pH 6.1 Peroxide step Mass concentration% 25 Time min 240 Temperature ° C 90 SiOa kg / ton 10 HzOa consumption kg / ton 13.5 32.0 end pH 10.2 10.3 Brightness% ISO 79.6 84.2 Limit viscosity dma / kg 520 447 -. 10 2 20 20 30 30 35 40 45 50 Example 2 = lmsy fifi 469 842 A softwood sulphate pulp with kappatal 13,3 (cooked from Scandinavian pine / spruce according to Fl pans 90 0663), oxygen delignified to kappatal 8.3 and ozone bleached in an acidic environment to kappatal 3.2, brightness 61% ISO, intrinsic viscosity 582 dm ° / kg, bleached according to the invention: Pretreatment similar to Example 1 Peroxide bleaching Mass concentration% Time min Temperature ° C SiO 2 kg / ton HzO 2 consumption kg / ton 7,3 Final pH 8, 9 Brightness% ISO 85,3 Limit viscosity dm ° / kg 536 Example 3 25 240 10 1 4.2 9.5 88.4 498 30.1 10.1 90.4 420 An oxygen delignified softwood sulphate pulp (boiled by Pinus taeda according to Fl pans 90 0663) with kappa number 9.9, ozone bleached to kappa number 4.8, brightness 54.5% ISO, intrinsic viscosity 607 dm ° / kg were pretreated and bleached according to the invention.

Förbehandling lika som Exempel 1 Peroxidblekning Massakoncentration % Tid min Temperatur °C SiOZ kg/ton HzOz-förbrukning kg/ton 7,9 Slut pH 10,2 Ljushet % ISO 81,3 Gränsviskositet dm°/kg 570 Exempel 4 25 240 10 14,6 10,4 85,3 534 29,6 10,6 87,8 459 En oxygendelignifierad biörksulfatmassa med kappatal 9,0, ljushet 59,4% ISO och gränsviskositet 996 dma/ kg blektes enligt uppfinningen: Förbehandling lika som Exempel 1 Peroxidblekning Massakoncentration % Tid min Temperatur °C SiOz kg/ton HzOz-förbrukning kg/ton 8,5 Slut pH 10,2 Ljushet % ISO 82,2 Gränsviskositet dma/kg 903 25 240 10 17,5 10,4 85,5 875 35 10,5 85,5 822 469 842 4 Uppfinningen är inte begränsad tili ovan angivna utföríngsformer utan kan varieras inom ramen för uppfinningstanken.Pretreatment similar to Example 1 Peroxide bleaching Mass concentration% Time min Temperature ° C SiOZ kg / ton HzOz consumption kg / ton 7.9 Final pH 10.2 Brightness% ISO 81.3 Limit viscosity dm ° / kg 570 Example 4 25 240 10 14, 6 10.4 85.3 534 29.6 10.6 87.8 459 An oxygen delignified birch sulphate pulp with kappa number 9.0, brightness 59.4% ISO and intrinsic viscosity 996 dma / kg was bleached according to the invention: Pretreatment similar to Example 1 Peroxide bleaching Mass concentration % Time min Temperature ° C SiOz kg / ton HzOz consumption kg / ton 8.5 End pH 10.2 Brightness% ISO 82.2 Limit viscosity dma / kg 903 25 240 10 17.5 10.4 85.5 875 35 10 .5 85.5 822 469 842 4 The invention is not limited to the above-mentioned embodiments but can be varied within the scope of the invention concept.

Claims (6)

469 842 5 Patentkrav469,842 Patent claims 1. Sätt att bleka sulfatmassa utan användning av klorhaltiga blekmedel, omfattande syrgasdelignifiering och eventuellt ozondelignifiering av massan till ett kappatal under 9,5 samt efterföljande peroxidblekning, k ä n n e t e c k n at a v att massan direkt efter delignifieringen förbehandlas med komplexbildare under 1 - 60 minuter, varvid massakoncentrationen är 1 - 15%, temperaturen 70 - 110°C och pH 5 - 7, att den så förbehandlade massan tvättas och awattnas till en koncentration av 18 - 40% och därefter peroxidbleks i alkalisk miljö i närvaro av silikat eller en organisk komplexbildare av fosfonsyra- eller karboxylsyratyp.Methods for bleaching sulphate pulp without the use of chlorine-containing bleaches, including oxygen delignification and possible ozone delignification of the pulp to a kappa number below 9.5 and subsequent peroxide bleaching, characterized in that the pulp is pretreated with complexing agents for 1 - 60 minutes immediately after delignification. the pulp concentration is 1 - 15%, the temperature 70 - 110 ° C and pH 5 - 7, that the pulp so pretreated is washed and dewatered to a concentration of 18 - 40% and then peroxide bleached in an alkaline environment in the presence of silicate or an organic complexing agent of phosphonic acid or carboxylic acid type. 2. Sätt enligt kravet 1, k ä n n e t e c k n at av att peroxidblekningen utföres under 1/2 - 5 timmar vid temperaturen 70 - 110°C.2. A method according to claim 1, characterized in that the peroxide bleaching is carried out for 1/2 - 5 hours at the temperature of 70 - 110 ° C. 3. Sätt enligt kravet 1 eller 2, k ä n n e t e c k n at a v att som komplexbildare vid förbehandlingen används EDTA eller DTPA.3. A method according to claim 1 or 2, characterized in that EDTA or DTPA is used as complexing agent in the pretreatment. 4. Sätt enligt något av föregående krav, k ä n n e t e c k n at a v att vid peroxidblekningen tillsätts silikat i en mängd av 2 - 30 kg/ton massa, uttryckt som SiOz.4. A method according to any one of the preceding claims, characterized in that silicate is added in the amount of 2 - 30 kg / ton pulp, expressed as SiO 2, during the peroxide bleaching. 5. Sätt enligt något av kraven 1 - 3, k ä n n e t e c k n at a v att vid peroxidblekningen tillsätts en organisk komplexbildare av fosfonsyra- eller karboxylsyratyp i en mängd av 0,5 - 5 kg /ton maSSâ.5. A method according to any one of claims 1 - 3, characterized in that in the peroxide bleaching an organic complexing agent of the phosphonic acid or carboxylic acid type is added in an amount of 0.5 - 5 kg / ton maSSâ. 6. Sätt enligt något av föregående krav, k ä n n e t e c k n at a v att blekningen utföres till en ljushet överstigande 83% ISO.6. A method according to any one of the preceding claims, characterized in that the bleaching is carried out to a brightness exceeding 83% ISO.
SE9200152A 1992-01-21 1992-01-21 Bleaching of chemical pulp with peroxide SE469842C (en)

Priority Applications (14)

Application Number Priority Date Filing Date Title
SE9200152A SE469842C (en) 1992-01-21 1992-01-21 Bleaching of chemical pulp with peroxide
DE69309893T DE69309893T2 (en) 1992-01-21 1993-01-12 BLEACHING OF CHEMICAL PULP
CA002124088A CA2124088A1 (en) 1992-01-21 1993-01-12 Bleaching of chemical pulp
EP93902618A EP0621915B1 (en) 1992-01-21 1993-01-12 Bleaching of chemical pulp
NZ246713A NZ246713A (en) 1992-01-21 1993-01-12 Bleaching of sulphate pulp comprising: oxygen delignification, pretreatment with complexing agent, washing then dewatering, and alkaline peroxide bleaching in presence of silicate or an organic complexing agent
AT93902618T ATE151826T1 (en) 1992-01-21 1993-01-12 BLEACHING CHEMICAL PULP
ES93902618T ES2102008T3 (en) 1992-01-21 1993-01-12 BLEACHING OF CHEMICAL PAPER PASTE.
PCT/SE1993/000012 WO1993014262A1 (en) 1992-01-21 1993-01-12 Bleaching of chemical pulp
JP5512379A JPH07503042A (en) 1992-01-21 1993-01-12 chemical pulp bleaching
BR9305761A BR9305761A (en) 1992-01-21 1993-01-12 Sulfate pulp bleaching process
AU34125/93A AU653467B2 (en) 1992-01-21 1993-01-12 Bleaching of sulphate pulp
ZA93317A ZA93317B (en) 1992-01-21 1993-01-18 Bleaching of chemical pulp
FI943431A FI943431A0 (en) 1992-01-21 1994-07-20 Bleaching of chemical pulp
NO942718A NO942718L (en) 1992-01-21 1994-07-20 Bleaching of chemical pulp

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE9200152A SE469842C (en) 1992-01-21 1992-01-21 Bleaching of chemical pulp with peroxide

Publications (4)

Publication Number Publication Date
SE9200152D0 SE9200152D0 (en) 1992-01-21
SE9200152L SE9200152L (en) 1993-07-22
SE469842B true SE469842B (en) 1993-09-27
SE469842C SE469842C (en) 1996-01-15

Family

ID=20385065

Family Applications (1)

Application Number Title Priority Date Filing Date
SE9200152A SE469842C (en) 1992-01-21 1992-01-21 Bleaching of chemical pulp with peroxide

Country Status (14)

Country Link
EP (1) EP0621915B1 (en)
JP (1) JPH07503042A (en)
AT (1) ATE151826T1 (en)
AU (1) AU653467B2 (en)
BR (1) BR9305761A (en)
CA (1) CA2124088A1 (en)
DE (1) DE69309893T2 (en)
ES (1) ES2102008T3 (en)
FI (1) FI943431A0 (en)
NO (1) NO942718L (en)
NZ (1) NZ246713A (en)
SE (1) SE469842C (en)
WO (1) WO1993014262A1 (en)
ZA (1) ZA93317B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5571377A (en) * 1993-06-08 1996-11-05 Kvaerner Pulping Technologies Ab Process for peroxide bleaching of chemical pulp in a pressurized bleach vessel

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE1004674A3 (en) * 1991-03-11 1993-01-12 Interox Internat Sa Method of laundering of chemical pulp and application of the method of laundering pulp kraft.
BE1006056A3 (en) * 1992-07-06 1994-05-03 Solvay Interox Method of laundering of chemical pulp.
SE501253C2 (en) * 1993-06-08 1994-12-19 Kvaerner Pulping Tech Chlorine-free bleaching of chemical pulp
CA2170398A1 (en) * 1993-09-02 1995-03-09 Michael A. Pikulin Improved method for bleaching lignocellulosic pulp
BE1007757A3 (en) * 1993-11-10 1995-10-17 Solvay Interox Method of laundering of chemical pulp.
FR2719854B1 (en) * 1994-05-11 1996-06-21 Atochem Elf Sa Process for the preparation of delignified and bleached chemical paper pulps.
SE514697C2 (en) 1994-08-31 2001-04-02 Valmet Fibertech Ab Elimination of metal ions in pulp bleaching

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8620222D0 (en) * 1986-08-20 1986-10-01 Abitibi Price Inc Peroxide bleaching
US4732650A (en) * 1986-09-15 1988-03-22 The Dow Chemical Company Bleaching of cellulosic pulps using hydrogen peroxide
ATE97179T1 (en) * 1989-06-06 1993-11-15 Eka Nobel Ab PROCESS FOR BLEACHING LIGNOCELLULOSE CONTAINING PULP.
FI93866B (en) * 1990-02-09 1995-02-28 Sunds Defibrator Rauma Oy Method for preparing sulphate pulp

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5571377A (en) * 1993-06-08 1996-11-05 Kvaerner Pulping Technologies Ab Process for peroxide bleaching of chemical pulp in a pressurized bleach vessel

Also Published As

Publication number Publication date
FI943431A (en) 1994-07-20
SE9200152D0 (en) 1992-01-21
NZ246713A (en) 1995-04-27
DE69309893T2 (en) 1997-11-06
JPH07503042A (en) 1995-03-30
DE69309893D1 (en) 1997-05-22
NO942718D0 (en) 1994-07-20
AU3412593A (en) 1993-08-03
SE9200152L (en) 1993-07-22
ES2102008T3 (en) 1997-07-16
EP0621915B1 (en) 1997-04-16
ZA93317B (en) 1993-08-19
AU653467B2 (en) 1994-09-29
SE469842C (en) 1996-01-15
CA2124088A1 (en) 1993-07-22
WO1993014262A1 (en) 1993-07-22
BR9305761A (en) 1997-01-28
NO942718L (en) 1994-07-20
FI943431A0 (en) 1994-07-20
ATE151826T1 (en) 1997-05-15
EP0621915A1 (en) 1994-11-02

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