EP0874082A1 - Kontinuierliches Verfahren zur Delignifizierung und/oder Bleiche von unbearbeitem oder wiederverwendetem Zellstoff - Google Patents
Kontinuierliches Verfahren zur Delignifizierung und/oder Bleiche von unbearbeitem oder wiederverwendetem Zellstoff Download PDFInfo
- Publication number
- EP0874082A1 EP0874082A1 EP98201186A EP98201186A EP0874082A1 EP 0874082 A1 EP0874082 A1 EP 0874082A1 EP 98201186 A EP98201186 A EP 98201186A EP 98201186 A EP98201186 A EP 98201186A EP 0874082 A1 EP0874082 A1 EP 0874082A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- treatment
- suspension
- oxygen
- equal
- compound
- 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.)
- Withdrawn
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- 238000004061 bleaching Methods 0.000 title claims abstract description 10
- 229920001131 Pulp (paper) Polymers 0.000 title claims description 21
- 238000010924 continuous production Methods 0.000 title claims description 5
- 239000000725 suspension Substances 0.000 claims abstract description 42
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 40
- 239000001301 oxygen Substances 0.000 claims abstract description 40
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 40
- -1 peroxide compound Chemical class 0.000 claims abstract description 24
- 239000007788 liquid Substances 0.000 claims abstract description 23
- 238000011282 treatment Methods 0.000 claims description 40
- 238000000034 method Methods 0.000 claims description 28
- 150000001875 compounds Chemical class 0.000 claims description 15
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 12
- 230000006837 decompression Effects 0.000 claims description 4
- 238000002360 preparation method Methods 0.000 claims description 4
- 238000002203 pretreatment Methods 0.000 claims description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 3
- 239000001257 hydrogen Substances 0.000 claims description 3
- 229910052739 hydrogen Inorganic materials 0.000 claims description 3
- 150000002978 peroxides Chemical class 0.000 claims description 3
- 238000004064 recycling Methods 0.000 abstract description 7
- 239000000126 substance Substances 0.000 abstract description 5
- XOJVVFBFDXDTEG-UHFFFAOYSA-N Norphytane Natural products CC(C)CCCC(C)CCCC(C)CCCC(C)C XOJVVFBFDXDTEG-UHFFFAOYSA-N 0.000 abstract 1
- 239000007791 liquid phase Substances 0.000 abstract 1
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 12
- 238000005406 washing Methods 0.000 description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 8
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical class [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 description 6
- 239000003153 chemical reaction reagent Substances 0.000 description 6
- 239000013505 freshwater Substances 0.000 description 5
- 239000000706 filtrate Substances 0.000 description 4
- 159000000003 magnesium salts Chemical class 0.000 description 4
- 235000019341 magnesium sulphate Nutrition 0.000 description 4
- 239000000123 paper Substances 0.000 description 4
- 239000003381 stabilizer Substances 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000002609 medium Substances 0.000 description 3
- 238000011144 upstream manufacturing Methods 0.000 description 3
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 2
- 229910019142 PO4 Inorganic materials 0.000 description 2
- ABLZXFCXXLZCGV-UHFFFAOYSA-N Phosphorous acid Chemical class OP(O)=O ABLZXFCXXLZCGV-UHFFFAOYSA-N 0.000 description 2
- 239000012736 aqueous medium Substances 0.000 description 2
- 150000007942 carboxylates Chemical class 0.000 description 2
- 238000010790 dilution Methods 0.000 description 2
- 239000012895 dilution Substances 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 229910052943 magnesium sulfate Inorganic materials 0.000 description 2
- 150000002894 organic compounds Chemical class 0.000 description 2
- 235000021317 phosphate Nutrition 0.000 description 2
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- 230000002087 whitening effect Effects 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- PQUCIEFHOVEZAU-UHFFFAOYSA-N Diammonium sulfite Chemical compound [NH4+].[NH4+].[O-]S([O-])=O PQUCIEFHOVEZAU-UHFFFAOYSA-N 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 229920002488 Hemicellulose Polymers 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 239000007844 bleaching agent Substances 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 238000010411 cooking Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000012634 fragment Substances 0.000 description 1
- 239000002655 kraft paper Substances 0.000 description 1
- 229920005610 lignin Polymers 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 235000015927 pasta Nutrition 0.000 description 1
- 150000004965 peroxy acids Chemical class 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 229910052979 sodium sulfide Inorganic materials 0.000 description 1
- GRVFOGOEDUUMBP-UHFFFAOYSA-N sodium sulfide (anhydrous) Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 description 1
- 229910021653 sulphate ion Inorganic materials 0.000 description 1
- 238000002560 therapeutic procedure Methods 0.000 description 1
Images
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
-
- 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
- D21C9/16—Bleaching ; Apparatus therefor with per compounds
- D21C9/163—Bleaching ; Apparatus therefor with per compounds with peroxides
Definitions
- the present invention relates to a continuous delignification and / or for bleaching virgin or recycled chemical pulp.
- whitening and delignification processes for pasta consists of subjecting a suspension of paper pulp to a sequence of several consecutive treatments. These treatments are often performed using chlorinated reagents. In order to protect the environment, many processes have been developed which no longer use chlorinated reagents. The environment can be further protected by reducing or even eliminating effluent discharges. This is practically achieved, in a continuous process, by withdrawing, after a treatment, part of the aqueous medium in which the paste paper was treated and putting this aqueous medium into operation upstream of this treatment.
- the present invention aims to provide a continuous process for bleaching and / or pulp delignification process in which effluent discharges are reduced even deleted while maintaining good performance in terms of delignification and bleaching.
- Another object of the present invention is to reduce the accumulation of organic compounds in the pulp suspension paper to be treated with a peroxidized compound, which results in a reduction in the chemical oxygen demand.
- the method according to the invention comprises steps (a) to (e). he can possibly include other intermediate steps.
- the method according to the invention can be an integral part of a manufacturing of virgin or recycled chemical pulp which consists of a sequence of more complex treatments.
- the process according to the invention can therefore be carried out at start of such manufacture of chemical pulp, i.e. immediately after baking the paper pulp.
- the method according to the invention can be carried out before and after other treatments of the paper pulp.
- the method according to the invention can be carried out at the end of the making paper pulp so that step (e) is the final step in manufacturing.
- step (e) that part of the liquid separated from the treated suspension is recycled in step (a).
- Step (a) of the process according to the invention consists in preparing a suspension pulp by mixing the pulp with a liquid. In general, it it is an aqueous liquid.
- the consistency of the suspension obtained is usually greater than or equal to 8%, in particular greater than or equal to 10%.
- the consistency is generally less than or equal to 35%, in particular less than or equal to 20%.
- Step (a) can be carried out in any device for washing or mixing of paper pulps known to those skilled in the art. She can in particular be carried out on a rotary filter or in a washing press.
- Step (b) of the method according to the invention comprises a first treatment with medium oxygen.
- This pretreatment with oxygen consists in putting the pulp suspension in contact with gaseous oxygen.
- Pretreatment with oxygen can be carried out at a higher pH or equal to 7, preferably greater than or equal to 8.
- the pH is generally lower or equal to 12.
- the pH is generally adjusted by adding a source of alkalinity. Sodium hydroxide is preferably used.
- Pretreatment with oxygen is usually carried out at a temperature greater than or equal to 80 ° C, more precisely 90 ° C, the values greater than or equal to 100 ° C being preferred.
- the temperature is generally less than or equal to 140 ° C, more precisely 130 ° C, the values lower or being 120 ° C being the most common.
- the temperature is usually set by adding an adequate quantity of water vapor to the suspension to be treated.
- Pretreatment with oxygen is most often carried out at a oxygen pressure greater than or equal to 1 bar, preferably 2 bars.
- the oxygen pressure is generally less than or equal to 10 bars, more precisely at 8 bars.
- Pretreatment with oxygen is commonly performed at a consistency greater than or equal to 8%, in particular greater than or equal to 10%.
- the consistency is generally less than or equal to 35%, in particular less than or equal to 20%.
- the duration of pretreatment with oxygen is most often longer or equal to 5 min, in particular 10 min.
- the duration is generally shorter or equal to 120 min, preferably 60 min.
- the pretreatment with oxygen is advantageously carried out at a pH from 7 to 12, a temperature from 80 to 140 ° C, an oxygen pressure from 1 to 10 bars, a consistency of 8 to 35% and for a period of 5 to 120 min.
- stabilizers can be chosen from magnesium salts, phosphates, phosphonates and carboxylates. Magnesium salts are preferred. Magnesium sulphates are especially preferred, in particular magnesium sulphate of formula MgSO 4 .7H 2 O.
- the pretreatment with oxygen is carried out in the presence of peroxide hydrogen.
- the amount of hydrogen peroxide added is most often greater than or equal to 0.05% by weight relative to the dry paste.
- the quantity is usually less than or equal to 2% by weight relative to the dry dough.
- Pretreatment with oxygen is followed by treatment with of a peroxidized compound.
- This peroxide compound can be chosen from hydrogen peroxide, peracids and ozone.
- the hydrogen peroxide in an alkaline medium.
- the treatment with a peroxide compound is generally carried out at a pH greater than or equal to 7, preferably greater than or equal to 9.
- the pH is usually less than or equal to 12.
- the pH is generally adjusted by addition a source of alkalinity in the suspension to be treated. We prefer to use sodium hydroxide.
- the treatment with a peroxide compound can be carried out at a temperature greater than or equal to 80 ° C, more precisely 90 ° C, the values greater than or equal to 100 ° C being preferred.
- the temperature is generally less than or equal to 140 ° C, more precisely 130 ° C, the values lower or being 120 ° C being the most common.
- the temperature is usually set by adding an adequate quantity of water vapor to the suspension to be treated. he can be interesting to operate the treatment with a peroxide compound at the same temperature as that of the pretreatment with oxygen.
- Treatment with a peroxide compound can be carried out under pressure atmospheric. In a preferred variant, it is produced under pressure in adding gaseous oxygen.
- the pressure is generally greater than or equal to 1 bar, preferably 2 bars.
- Oxygen pressure is generally lower or equal to 10 bars, more precisely to 8 bars. It can be interesting to operate the treatment using a peroxidized compound at the same pressure as pretreatment with oxygen. In another interesting variant step (b) does not include a decompression step between the pretreatment at oxygen and treatment with the peroxide compound.
- Treatment with a peroxide compound is commonly performed at a consistency greater than or equal to 8%, in particular greater than or equal to 10%.
- the consistency is generally less than or equal to 35%, in particular less than or equal to 20%.
- the duration of treatment with a peroxide compound is most often greater than or equal to 30 min, in particular 60 min.
- the duration is generally less than or equal to 240 min, preferably 120 min.
- the amount of peroxide compound used is generally greater or equal to 0.05%, in particular to 1% by weight relative to the dry paste. She is usually less than or equal to 8%, especially 2.5% by weight per compared to dry dough.
- the treatment with a peroxide compound is advantageously carried out at a temperature of 80 to 140 ° C, a pressure of 1 to 10 bar, a consistency from 8 to 35%, a pH from 7 to 12, for a period of 30 to 240 min and putting using an amount of peroxide compound less than or equal to 8% by weight compared to dry dough.
- Treatment with a peroxide compound is preferably carried out at a temperature of 100 to 120 ° C, a pressure of 2 to 8 bars, a consistency of 10 to 20%, a pH of 9 to 12, for a period of 60 to 120 min and using an amount of peroxide compound from 1 to 2.5% by weight compared to the dry dough.
- stabilizers can be chosen from magnesium salts, phosphates, phosphonates and carboxylates. Magnesium salts are preferred. Magnesium sulphates are especially preferred, in particular magnesium sulphate of formula MgSO 4 .7H 2 O.
- step (b) it turned out to be advantageous, during step (b), not to modify so drastic conditions of temperature, pressure, pH and consistency between oxygen pretreatment and treatment with peroxide compound.
- Step (b) of the process according to the invention may also contain other treatments. However, good results are obtained when step (b) does not no intermediate washing between pre-treatment with oxygen and treatment with a peroxide compound. Good results are also obtained when step (b) does not include a decompression step between pre-treatment with oxygen and treatment with a peroxidized compound. Preferably, step (b) does not include washing intermediate or intermediate decompression. The best results are obtained when step (b) does not include any intermediate step between the pretreatment with oxygen and treatment with a compound peroxide.
- washing we mean a step in which the liquid of the pulp suspension is replaced by another liquid that does not contain bleaching agent.
- Step (d) of the process according to the invention consists in separating the suspension from paper pulp which has been treated in step (b) and collected in step (c), two parts, namely the liquid on the one hand and the pulp on the other.
- This separation can be carried out by filtration so as to modify the consistency of the pulp suspension. It can alternatively be carried out by washing in replacing the suspension liquid with another liquid.
- the consistency of the suspension may vary or may be kept constant.
- the other liquid is usually fresh water not yet used in a any pulp treatment.
- Step (d) can be carried out in any washing device or mixture of paper pulp known to those skilled in the art. It can in particular be carried out on a rotary filter or in a washing press.
- step (d) contains fragments of lignin, hemicellulose and cellulose which are dissolved during the treatments of step (b). These soluble organic compounds cause increased demand liquid oxygen and would consume part of the compound peroxidized when the liquid is used in a subsequent treatment of bleaching and / or delignification using a peroxide compound.
- step (e) of the process according to the invention the liquid separated from the suspension of the pulp already treated to mix it with a pulp untreated paper and thereby form a suspension of pulp treat.
- Step (a) of the process according to the invention is carried out in the tank 1 which is supplied with a suspension of paper via line 2 and liquid via line 3.
- the suspension prepared in the tank 1 is transferred via the conduit 4 into a first container 5 in which the suspension is subjected to pretreatment with oxygen.
- the conduit 4 is supplied with oxygen, possibly with other reagents and possibly with water vapor via line 6.
- the pretreated suspension is withdrawn from reactor 5 via line 7 and transferred to a second container 8. In this second container, the pretreated suspension is subjected to treatment with a peroxidized compound.
- the peroxidized compound, possibly other reagents and possibly water vapor is introduced into the conduit 7 via the conduit 9.
- the suspension pretreated with oxygen and treated with the peroxide compound is then withdrawn from the container 8 via the conduit 10 and transferred to the tank 11.
- part of the liquid is separated from the paper pulp.
- the liquid thus separated is withdrawn from the tank 11 via the conduit 3, part of which is recycled to the tank 1 to prepare another suspension to be treated. Part of the recycled liquid can be purged via line 12.
- the paper pulp is withdrawn from tank 11 via the conduit 13.
- the method according to the invention can be applied to any paper pulp virgin or recycled chemical.
- chemical paper pulp is meant pulp having undergone a minor treatment in the presence of chemical reagents.
- chemical reagents sodium sulfide in alkaline medium (kraft or sulphate cooking) or magnesium, calcium or sulphite ammonium or any other organic solvent.
- Example 1 the description of which follows illustrates the method according to the invention.
- Example 2 is given for comparison.
- the kappa index was measured according to ISO R302 and the whiteness according to the ISO 3688 standard.
- a paper pulp with an initial whiteness of 46.8 ° ISO and a kappa index of 9.9 has been subjected to a whitening and O-PO delignification with recycling of effluent from the PO stage upstream of the stage O.
- Stage O was carried out at 10% consistency, 6 bar pressure, a temperature of 100 ° C for a period of 30 minutes and adding 1.5% NaOH compared to dry dough. After 30 minutes, 2% peroxide hydrogen was added to the dough without the dough being depressurized and then the PO stage begins. The duration of the PO stage was set at 90 minutes. After 90 minutes, the dough leaving the PO stage was filtered and the filtrate was returned to a new paste as dilution water in the preparation of the paste for the stage at oxygen.
- This cycle has been repeated a sufficient number of times (6) to arrive at a system stationary in which the concentration of impurities in the stage filtrate (PO) is stable.
- a paper pulp with an initial whiteness of 44.5 ° ISO and a kappa of 7.8 has been subjected to a bleaching and delignification treatment PO with recycling of effluent from PO stage upstream from PO stage.
- the PO stage was carried out at 12% consistency, 6 bar pressure, a temperature of 110 ° C for a period of 60 minutes and adding 1.5% NaOH and 2% hydrogen peroxide compared to the dry pulp. After 60 minutes, the dough leaving the PO stage was filtered and the filtrate was put back on a new paste as dilution water in the preparation of the paste for the PO stage.
- This cycle has been repeated a sufficient number of times (6) to arrive at a system stationary in which the concentration of impurities in the stage filtrate (PO) is stable.
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 |
|---|---|---|---|
| BE9700383A BE1011129A4 (fr) | 1997-04-25 | 1997-04-25 | Procede continu de delignification et/ou de blanchiment de pate a papier chimique vierge ou recyclee. |
| BE9700383 | 1997-04-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| EP0874082A1 true EP0874082A1 (de) | 1998-10-28 |
Family
ID=3890489
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP98201186A Withdrawn EP0874082A1 (de) | 1997-04-25 | 1998-04-14 | Kontinuierliches Verfahren zur Delignifizierung und/oder Bleiche von unbearbeitem oder wiederverwendetem Zellstoff |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0874082A1 (de) |
| JP (1) | JPH10310988A (de) |
| BE (1) | BE1011129A4 (de) |
| BR (1) | BR9801454A (de) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2040763A1 (de) * | 1970-05-11 | 1971-11-18 | Kymin Oy Kymmene Ab | Verfahren zum Bleichen zellulosehaltiger Stoffe |
| EP0019963A1 (de) * | 1979-05-25 | 1980-12-10 | INTEROX Société Anonyme | Verfahren zur Delignifizierung und zum Bleichen von chemischen und halbchemischen Zellstoffen |
| EP0171575A1 (de) * | 1984-08-01 | 1986-02-19 | Degussa Aktiengesellschaft | Verfahren zur Delignifizierung und Bleiche von Zellstoffen |
| EP0401149A1 (de) * | 1989-05-19 | 1990-12-05 | Fmc Corporation | Mit Wasserstoffperoxid verstärkte Sauerstoffdelignifizierung |
-
1997
- 1997-04-25 BE BE9700383A patent/BE1011129A4/fr not_active IP Right Cessation
-
1998
- 1998-04-14 EP EP98201186A patent/EP0874082A1/de not_active Withdrawn
- 1998-04-24 BR BR9801454-4A patent/BR9801454A/pt not_active Application Discontinuation
- 1998-04-27 JP JP11688898A patent/JPH10310988A/ja active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2040763A1 (de) * | 1970-05-11 | 1971-11-18 | Kymin Oy Kymmene Ab | Verfahren zum Bleichen zellulosehaltiger Stoffe |
| EP0019963A1 (de) * | 1979-05-25 | 1980-12-10 | INTEROX Société Anonyme | Verfahren zur Delignifizierung und zum Bleichen von chemischen und halbchemischen Zellstoffen |
| EP0171575A1 (de) * | 1984-08-01 | 1986-02-19 | Degussa Aktiengesellschaft | Verfahren zur Delignifizierung und Bleiche von Zellstoffen |
| EP0401149A1 (de) * | 1989-05-19 | 1990-12-05 | Fmc Corporation | Mit Wasserstoffperoxid verstärkte Sauerstoffdelignifizierung |
Also Published As
| Publication number | Publication date |
|---|---|
| BE1011129A4 (fr) | 1999-05-04 |
| JPH10310988A (ja) | 1998-11-24 |
| BR9801454A (pt) | 1999-09-28 |
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