CA1180510A - Process for removing residual lignin in chemical cellulose pulp - Google Patents
Process for removing residual lignin in chemical cellulose pulpInfo
- Publication number
- CA1180510A CA1180510A CA000399940A CA399940A CA1180510A CA 1180510 A CA1180510 A CA 1180510A CA 000399940 A CA000399940 A CA 000399940A CA 399940 A CA399940 A CA 399940A CA 1180510 A CA1180510 A CA 1180510A
- Authority
- CA
- Canada
- Prior art keywords
- pulp
- alkali
- stage
- oxygen gas
- gas
- 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
Links
- 238000000034 method Methods 0.000 title claims abstract description 84
- 230000008569 process Effects 0.000 title claims abstract description 54
- 229920002678 cellulose Polymers 0.000 title claims abstract description 53
- 239000001913 cellulose Substances 0.000 title claims abstract description 53
- 229920005610 lignin Polymers 0.000 title claims abstract description 17
- 239000000126 substance Substances 0.000 title abstract description 7
- 239000003513 alkali Substances 0.000 claims abstract description 76
- 238000011282 treatment Methods 0.000 claims abstract description 74
- 239000007789 gas Substances 0.000 claims abstract description 72
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 claims abstract description 41
- 229910001882 dioxygen Inorganic materials 0.000 claims abstract description 40
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 37
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 37
- 239000001301 oxygen Substances 0.000 claims abstract description 37
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 30
- 230000003213 activating effect Effects 0.000 claims abstract description 26
- 230000004913 activation Effects 0.000 claims description 15
- 239000002699 waste material Substances 0.000 claims description 11
- 238000005406 washing Methods 0.000 claims description 8
- 230000009467 reduction Effects 0.000 claims description 7
- 229920002488 Hemicellulose Polymers 0.000 claims description 5
- 230000015556 catabolic process Effects 0.000 claims description 4
- 238000006731 degradation reaction Methods 0.000 claims description 4
- 238000004537 pulping Methods 0.000 claims description 3
- 239000012978 lignocellulosic material Substances 0.000 claims description 2
- 239000007791 liquid phase Substances 0.000 claims 1
- 239000012071 phase Substances 0.000 claims 1
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 abstract description 75
- 150000001720 carbohydrates Chemical class 0.000 abstract description 6
- 235000014633 carbohydrates Nutrition 0.000 abstract description 6
- 239000000203 mixture Substances 0.000 abstract description 6
- 239000007844 bleaching agent Substances 0.000 abstract description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 60
- MGWGWNFMUOTEHG-UHFFFAOYSA-N 4-(3,5-dimethylphenyl)-1,3-thiazol-2-amine Chemical compound CC1=CC(C)=CC(C=2N=C(N)SC=2)=C1 MGWGWNFMUOTEHG-UHFFFAOYSA-N 0.000 description 44
- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 description 44
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 41
- 229910052757 nitrogen Inorganic materials 0.000 description 30
- 238000004061 bleaching Methods 0.000 description 29
- 238000006243 chemical reaction Methods 0.000 description 19
- 238000001994 activation Methods 0.000 description 15
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 11
- 239000000460 chlorine Substances 0.000 description 11
- 229910052801 chlorine Inorganic materials 0.000 description 11
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 9
- 235000008331 Pinus X rigitaeda Nutrition 0.000 description 8
- 235000011613 Pinus brutia Nutrition 0.000 description 8
- 241000018646 Pinus brutia Species 0.000 description 8
- 150000002500 ions Chemical class 0.000 description 7
- 239000011777 magnesium Substances 0.000 description 7
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 description 6
- 239000007788 liquid Substances 0.000 description 6
- 230000007423 decrease Effects 0.000 description 5
- 239000011261 inert gas Substances 0.000 description 5
- 101150080656 DIO2 gene Proteins 0.000 description 4
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 4
- 239000011121 hardwood Substances 0.000 description 4
- 239000011734 sodium Substances 0.000 description 4
- 229910052708 sodium Inorganic materials 0.000 description 4
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 3
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 3
- WFPZPJSADLPSON-UHFFFAOYSA-N dinitrogen tetraoxide Chemical compound [O-][N+](=O)[N+]([O-])=O WFPZPJSADLPSON-UHFFFAOYSA-N 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 229910052749 magnesium Inorganic materials 0.000 description 3
- 229960003390 magnesium sulfate Drugs 0.000 description 3
- 229910052943 magnesium sulfate Inorganic materials 0.000 description 3
- 235000019341 magnesium sulphate Nutrition 0.000 description 3
- 229940091250 magnesium supplement Drugs 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 239000011122 softwood Substances 0.000 description 3
- 241000218657 Picea Species 0.000 description 2
- 229920001131 Pulp (paper) Polymers 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000010924 continuous production Methods 0.000 description 2
- 238000010411 cooking Methods 0.000 description 2
- 230000006378 damage Effects 0.000 description 2
- 230000029087 digestion Effects 0.000 description 2
- 230000003292 diminished effect Effects 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- OSVXSBDYLRYLIG-UHFFFAOYSA-N dioxidochlorine(.) Chemical compound O=Cl=O OSVXSBDYLRYLIG-UHFFFAOYSA-N 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- JEIPFZHSYJVQDO-UHFFFAOYSA-N ferric oxide Chemical compound O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 2
- ZZUFCTLCJUWOSV-UHFFFAOYSA-N furosemide Chemical compound C1=C(Cl)C(S(=O)(=O)N)=CC(C(O)=O)=C1NCC1=CC=CO1 ZZUFCTLCJUWOSV-UHFFFAOYSA-N 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 2
- 238000011065 in-situ storage Methods 0.000 description 2
- 239000000543 intermediate Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 125000000449 nitro group Chemical group [O-][N+](*)=O 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 230000008016 vaporization Effects 0.000 description 2
- HFGHRUCCKVYFKL-UHFFFAOYSA-N 4-ethoxy-2-piperazin-1-yl-7-pyridin-4-yl-5h-pyrimido[5,4-b]indole Chemical compound C1=C2NC=3C(OCC)=NC(N4CCNCC4)=NC=3C2=CC=C1C1=CC=NC=C1 HFGHRUCCKVYFKL-UHFFFAOYSA-N 0.000 description 1
- SUBDBMMJDZJVOS-UHFFFAOYSA-N 5-methoxy-2-{[(4-methoxy-3,5-dimethylpyridin-2-yl)methyl]sulfinyl}-1H-benzimidazole Chemical compound N=1C2=CC(OC)=CC=C2NC=1S(=O)CC1=NC=C(C)C(OC)=C1C SUBDBMMJDZJVOS-UHFFFAOYSA-N 0.000 description 1
- 241000251468 Actinopterygii Species 0.000 description 1
- 239000004155 Chlorine dioxide Substances 0.000 description 1
- 101100353161 Drosophila melanogaster prel gene Proteins 0.000 description 1
- 241000196324 Embryophyta Species 0.000 description 1
- 241001547070 Eriodes Species 0.000 description 1
- 101100106077 Escherichia coli (strain K12) ygeI gene Proteins 0.000 description 1
- 241001397173 Kali <angiosperm> Species 0.000 description 1
- 241001072332 Monia Species 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- 241001296096 Probles Species 0.000 description 1
- RJKFOVLPORLFTN-LEKSSAKUSA-N Progesterone Chemical compound C1CC2=CC(=O)CC[C@]2(C)[C@@H]2[C@@H]1[C@@H]1CC[C@H](C(=O)C)[C@@]1(C)CC2 RJKFOVLPORLFTN-LEKSSAKUSA-N 0.000 description 1
- HFCYZXMHUIHAQI-UHFFFAOYSA-N Thidiazuron Chemical compound C=1C=CC=CC=1NC(=O)NC1=CN=NS1 HFCYZXMHUIHAQI-UHFFFAOYSA-N 0.000 description 1
- -1 Thus Chemical compound 0.000 description 1
- 208000027418 Wounds and injury Diseases 0.000 description 1
- 240000008042 Zea mays Species 0.000 description 1
- 235000005824 Zea mays ssp. parviglumis Nutrition 0.000 description 1
- 235000002017 Zea mays subsp mays Nutrition 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- PYKYMHQGRFAEBM-UHFFFAOYSA-N anthraquinone Natural products CCC(=O)c1c(O)c2C(=O)C3C(C=CC=C3O)C(=O)c2cc1CC(=O)OC PYKYMHQGRFAEBM-UHFFFAOYSA-N 0.000 description 1
- 150000004056 anthraquinones Chemical class 0.000 description 1
- 239000007900 aqueous suspension Substances 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 238000010923 batch production Methods 0.000 description 1
- 238000009530 blood pressure measurement Methods 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 description 1
- 238000007084 catalytic combustion reaction Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000005660 chlorination reaction Methods 0.000 description 1
- 235000019398 chlorine dioxide Nutrition 0.000 description 1
- 235000005822 corn Nutrition 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 239000000539 dimer Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 208000014674 injury Diseases 0.000 description 1
- 239000013067 intermediate product Substances 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- VTHJTEIRLNZDEV-UHFFFAOYSA-L magnesium dihydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 description 1
- 239000000347 magnesium hydroxide Substances 0.000 description 1
- 229910001862 magnesium hydroxide Inorganic materials 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 230000003340 mental effect Effects 0.000 description 1
- 239000003471 mutagenic agent Substances 0.000 description 1
- 231100000707 mutagenic chemical Toxicity 0.000 description 1
- APVPOHHVBBYQAV-UHFFFAOYSA-N n-(4-aminophenyl)sulfonyloctadecanamide Chemical compound CCCCCCCCCCCCCCCCCC(=O)NS(=O)(=O)C1=CC=C(N)C=C1 APVPOHHVBBYQAV-UHFFFAOYSA-N 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 229940099990 ogen Drugs 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 238000001139 pH measurement Methods 0.000 description 1
- 150000002978 peroxides Chemical class 0.000 description 1
- 239000005077 polysulfide Substances 0.000 description 1
- 229920001021 polysulfide Polymers 0.000 description 1
- 150000008117 polysulfides Polymers 0.000 description 1
- 238000003918 potentiometric titration Methods 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000011541 reaction mixture Substances 0.000 description 1
- 238000007430 reference method Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 241000894007 species Species 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 238000009827 uniform distribution Methods 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
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
- D21C9/1005—Pretreatment of the pulp, e.g. degassing the pulp
-
- 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
- D21C9/1068—Bleaching ; Apparatus therefor with O2
-
- 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
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Wood Science & Technology (AREA)
- Paper (AREA)
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE8101815A SE425674B (sv) | 1981-03-23 | 1981-03-23 | Forfarande for delignifiering av cellulosamassa med kvevedioxid och syrgas |
| SE81-01815-2 | 1981-03-31 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1180510A true CA1180510A (en) | 1985-01-08 |
Family
ID=20343394
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000399940A Expired CA1180510A (en) | 1981-03-23 | 1982-03-31 | Process for removing residual lignin in chemical cellulose pulp |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS57161185A (enrdf_load_stackoverflow) |
| AU (1) | AU550433B2 (enrdf_load_stackoverflow) |
| CA (1) | CA1180510A (enrdf_load_stackoverflow) |
| FR (1) | FR2502203A1 (enrdf_load_stackoverflow) |
| NZ (1) | NZ199697A (enrdf_load_stackoverflow) |
| SE (1) | SE425674B (enrdf_load_stackoverflow) |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1505070A (en) * | 1974-06-11 | 1978-03-22 | Canadian Ind | Process for bleaching of lignocellulosic material |
| CA1070909A (en) * | 1976-05-04 | 1980-02-05 | Canadian Industries Limited | Nitrogen dioxide-oxygen delignification |
-
1981
- 1981-03-23 SE SE8101815A patent/SE425674B/sv not_active IP Right Cessation
-
1982
- 1982-02-11 NZ NZ199697A patent/NZ199697A/en unknown
- 1982-03-05 AU AU81151/82A patent/AU550433B2/en not_active Ceased
- 1982-03-08 JP JP57037131A patent/JPS57161185A/ja active Granted
- 1982-03-23 FR FR8204875A patent/FR2502203A1/fr active Granted
- 1982-03-31 CA CA000399940A patent/CA1180510A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| AU550433B2 (en) | 1986-03-20 |
| JPS57161185A (en) | 1982-10-04 |
| NZ199697A (en) | 1986-01-24 |
| AU8115182A (en) | 1982-09-30 |
| JPS6360158B2 (enrdf_load_stackoverflow) | 1988-11-22 |
| SE8101815L (enrdf_load_stackoverflow) | 1982-09-24 |
| SE425674B (sv) | 1982-10-25 |
| FR2502203B1 (enrdf_load_stackoverflow) | 1984-11-23 |
| FR2502203A1 (fr) | 1982-09-24 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4222819A (en) | Process for the acid bleaching of cellulose pulp with peroxides | |
| US5310458A (en) | Process for bleaching lignocellulose-containing pulps | |
| FI111964B (fi) | Menetelmä lignoselluloosapitoisen massan valkaisemiseksi | |
| DE69206313T2 (de) | Verfahren zum Bleichen von Lignocellulose enthaltendem Material. | |
| DE3017712C2 (de) | Verfahren zur alkalischen Extraktion von Fasermaterial enthaltenden Cellulosesuspensionen nach Behandlung mit Chlor oder Chlordioxid oder Mischungen davon | |
| CA2040871C (en) | Process for bleaching of lignocellulose-containing material | |
| CA1180509A (en) | Process for activating cellulose pulp with no and/or no.sub.2 and oxygen in the presence of nitric acid and then delignifying bleaching the activated cellulose pulp | |
| EP0395792A2 (en) | Procedure for the bleaching of pulp | |
| CA1175610A (en) | Process for alkaline oxygen gas bleaching of cellulose pulp | |
| US5645687A (en) | Process for manufacturing bleached pulp with reduced chloride production | |
| CA1147909A (en) | Method for delignifying and/or bleaching cellulose pulp | |
| CA1180510A (en) | Process for removing residual lignin in chemical cellulose pulp | |
| EP0553649B1 (en) | Process for delignifying a cellulose pulp | |
| US4750973A (en) | Process for reducing carbohydrate losses in the sulfate pulping of wood by pretreating the wood with oxygen and nitrogen oxides | |
| CZ132895A3 (en) | Bleaching process of pulp containing ligno-cellulose | |
| DE19729155A1 (de) | Verfahren zur Herstellung von Pulpe | |
| EP0185858B1 (de) | Verfahren zur Delignifizierung von Sulfatzellstoffen | |
| SU1730299A1 (ru) | Способ получени целлюлозы дл химической переработки | |
| CA1149111A (en) | Process for delignifying and/or bleaching cellulose pulp | |
| RU2009279C1 (ru) | Способ подготовки льняной ровницы к мокрому прядению | |
| JP2812056B2 (ja) | リグノセルロース物質の漂白方法 | |
| NZ198925A (en) | Method for bleaching cellulose pulp using nitrogen oxides and oxygen followed by an alkali treatment | |
| NO159542B (no) | Fremgangsmaate ved delignifisering av cellulosemasse. | |
| CA2130906A1 (en) | A method for the enzymatic treatment of chemical pulp before bleaching |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEC | Expiry (correction) | ||
| MKEX | Expiry |