EP0884415A1 - Method of washing pulp in connection with bleaching - Google Patents
Method of washing pulp in connection with bleaching Download PDFInfo
- Publication number
- EP0884415A1 EP0884415A1 EP98113684A EP98113684A EP0884415A1 EP 0884415 A1 EP0884415 A1 EP 0884415A1 EP 98113684 A EP98113684 A EP 98113684A EP 98113684 A EP98113684 A EP 98113684A EP 0884415 A1 EP0884415 A1 EP 0884415A1
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- EP
- European Patent Office
- Prior art keywords
- washer
- bleaching
- stage
- pulp
- recited
- 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.)
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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
- D21C9/1026—Other features in bleaching processes
-
- 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
- D21C9/02—Washing ; Displacing cooking or pulp-treating liquors contained in the pulp by fluids, e.g. wash water or other pulp-treating agents
-
- 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
- D21C9/1026—Other features in bleaching processes
- D21C9/1036—Use of compounds accelerating or improving the efficiency of the processes
-
- 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
- D21C9/1026—Other features in bleaching processes
- D21C9/1042—Use of chelating agents
-
- 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
- D21C9/147—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
- D21C9/16—Bleaching ; Apparatus therefor with per compounds
- D21C9/163—Bleaching ; Apparatus therefor with per compounds with peroxides
Definitions
- the present invention relates to a new kind of a method of producing pulp by using chlorine-free chemicals.
- the invention is especially related to ozone bleaching of pulp without preceding removal of heavy metals.
- Typical bleaching sequences by which pulp has earlier been bleached are, for example, OOAZEZPZ, OAZEZPZ, OOAZEZP and OAZEZP. These sequences thus include one or more oxygen bleaching stages (O), an A-stage (acid washing), an ozone stage (Z), an extraction stage (E), a second ozone stage (Z) and a peroxide stage (P), and possibly a third ozone stage (Z).
- the extraction stage (E) may be an oxidizing peroxide extraction stage or a conventional oxidizing extraction stage.
- the ozone bleaching stages are preferably carried out with pulp having the consistency of about 5-18%.
- washing stages in other words bleaching stages alternate with washing stages, i.e. washers, by which the chemicals separated from the fibers as reaction products or otherwise in each bleaching stage are removed from the suspension. Since the washers form a considerable part of the investment costs in a bleaching plant, the number of the washers should, of course, be limited as much as possible, if it is only possible without risking the quality of the final product.
- EP-A-0 426 652 discloses several bleaching sequences where ozone has been used in combination with peroxide and oxygen. For instance, sequences like EOP-Z-PE-Z-PE, EOP-Z-PE, O-Z-EO-Z-P, O-Z-EOP-Z-P and O-Z-EO-Z-D were discussed. However, the publication does not take into account the presence of heavy metals in the pulp in spite of the fact that at least one of the examples discusses bleaching of kraft pulp by means of a peroxide containing compound.
- EP-A-0 512 978 discloses a multi-stage bleaching process using both ozone and peroxide for bleaching pulp. The document does not pay any attention to the removal of heavy metals from pulp before bleaching with peroxide.
- EP-A-0 402 335 discloses a process for bleaching lignocellulose-containing pulps by means of peroxide containing substance.
- the main teaching of the document is to alter the trace metal profile of the pulp by means of a separate treatment with a complexing agent.
- the document teaches the importance of treating pulp prior to a peroxide stage in a separate metal removing stage.
- the treatment comprises a washing stage between the treatment with complex formers and the peroxide stage.
- a conventional bleaching + screening plant has thus included four or five bleaching stages and one screening and/or vortex cleaning stage, which the washing stage separates from each other.
- the present invention compresses these five to six stages into three stages and thus almost halves the investment costs of a bleaching plant and a screening plant.
- pulp is bleached with a sequence beginning with ozone and without the removal of heavy metals preceding the ozone stage.
- pulp is bleached with a three-stage sequence (ZT)(EOP)(ZP) without the removal of heavy metals preceding the sequence, in which
- a bleaching sequence is provided using a high consistency pulp tower 10, from which pulp is discharged and fed, for example, with an MC® (i.e. fluidizing) pump 12 into an ozone reactor 14, from which pulp is preferably discharged by means of a gas separator 16 into a first reaction tower 18.
- Pulp is preferably discharged from tower 18 into a washer 22 by means of an MC® pump 20.
- the washer may be a conventional DRUM DISPLACERTM washer or a conventional pressure diffuser. Pulp is preferably pumped from washer 22 by an MC® pump 24 into an oxygen reactor 26, and from reactor 26 into a second reaction tower 28.
- a second washer 32 preferably a DRUM DISPLACERTM
- ozone in a carrier gas
- oxygen may be mixed prior to the oxygen reactor 26 with mixer 62 and the mixture of ozone and carrier gas prior to the second ozone reactor 36.
- the mixers 60, 62 are preferably AHLMIXERTM type fluidizing mixers, which are able to mix very large amounts of gas into fiber suspensions, including medium consistency suspensions.
- Fig. 1 teaches how, in order to adjust the pH value of the pulp for the first ozone stage and the removal of heavy metals subsequent thereto, acid may be supplied into the pulp, for example, in the pump 12.
- complex formers such as EDTA, and/or alkali may be added to the pulp. If too much magnesium is removed from the pulp by washer 22, it may be added, for example, with the alkali either in pump 24 and/or in the discharge from the oxygen reactor 26, or in any other appropriate way.
- Another possibility to adjust the pH of the pulp for the second ozone treatment is to feed acid subsequent to the second washer 32 in pump 34 or in some other suitable way.
- peroxide and/or magnesium may be added into the pulp, as illustrated in Fig. 1.
- All the reaction towers 18, 28 and 40 in Fig. 1 are shown as of the down flow type. Alternatively, they may be of the up flow type, as is shown in Fig. 2.
- the only significant difference between Figs. 1 and 2 is the flow direction of the reaction towers.
- components functionally equivalent to or the same as the components in the Fig. 1 embodiment are illustrated by the same reference numeral, only preceded by a "1".
- pumps 20, 30 and 42 of Fig. 1 are replaced by pumps 120', 130' and 142', because they have been relocated at the other side of the reaction tower, in other words instead of feeding washers 22, 32 and 44 as illustrated in Fig. 1 they feed pulp to the reaction towers 118, 128 and 140 in the embodiments of Fig. 2.
- pulp is cooked, for example with a continuous EMCC digester, sold by Kamyr Inc., of Glens Falls, New York, to a low kappa number, whereafter the kappa number is further decreased by oxygen bleaching to a value of about 14 or below.
- a continuous EMCC digester sold by Kamyr Inc., of Glens Falls, New York
- oxygen bleaching to a value of about 14 or below.
- hot alkali extraction and oxygen bleaching a kappa range of 14 - 5 is obtained both with soft wood and birch.
- a kappa number of 14 is sufficient in order to carry our the final bleaching with chlorine-free bleaching chemicals and yet reach a full brightness defined by ISO 86 (preferably ISO 88).
- ISO 86 preferably ISO 88
- the kraft pulp is bleached subsequent to the pulp washing and according to the invention without a separate removal of heavy metals, for example, with a sequence in accordance with Fig. 1, which is described more in detail below.
- Pulp may be treated, if so required, with enzymes prior to the sequence in accordance with the present invention.
- Pulp is brought from the high consistency pulp tower 10 to the first bleaching stage, which is a (ZT) stage.
- the first bleaching stage which is a (ZT) stage.
- pulp is bleached with ozone, the dosing being about 2-10 kg/adt, pH about 2- 7, and temperature about 40-70°C.
- the pH value of pulp is adjusted by adding acid to the bottom of the high consistency tower 10, pump 12 (or the discharge to pump 12 as seen in Fig. 1), or chemical mixer 60.
- the ozone having reacted, the residual gas is removed from the pulp preferably in a gas separator 16 and the treatment of heavy metals begins in the first reaction tower 18 in the T portion
- the T portion of the (ZT) stage may be carried out, for example, in the following ways.
- the first alternative is to allow the pH value of the pulp to decrease to the range of 2 - 4, whereby the majority of the heavy metals are dissolved into the filtrate phase and may be washed off in the thickener or washer 22 following that stage.
- the disadvantage here is that the majority of the magnesium (Mg) is also discharged, so that it is possible that magnesium must be added to the pulp, mostly in the form of magnesium sulphate, for the oxygen and/or peroxide stages following later on in the sequence.
- T portion of the (ZT) stage Another way to carry out the T portion of the (ZT) stage is to use complex formers, for example, EDTA.
- the T portion of the (ZT) stage is then carried out in the pH range of about 4-7 and it is advantageous also to have the pH of Z portion of the (ZT) stage preceding T portion above 4.
- manganese which is harmful in the oxygen stages
- Filtrate S 1 of the washer 22 subsequent to the (ZT) stage may be brought to pulp washing prior to the (ZT) stage, or passed to the sewer or to the recovery of cooking chemicals.
- the (ZT) stage is followed in Fig. 1 by an (EOP) stage.
- the oxygen dose is about 2-6 kg/adt and the peroxide dose about 10-20 kg/adt. In some special cases it is possible to run the process completely without oxygen.
- Temperature in the (EOP) stage is about 60-95°C, pH about 9-12, and the duration is about 2-8 hours. If required, magnesium may be added as a protective chemical.
- the (EOP) stage is followed by washing, which gives filtrate S 2 .
- the filtrate S 2 may be taken to pulp washing prior to or subsequent to the (ZT) stage, sewer, or recovery of chemicals.
- the (EOP) stage is followed in Fig. 1 by a second ozone bleaching stage, i.e. an (ZP) stage.
- the ozone portion of the (ZP) stage is normally carried out in the processes in accordance with the prior art in cold, acid conditions in order to have the ozone react properly.
- the P portion of the (ZP) stage is carried out according to the teachings of the prior art in hot, alkali conditions in order to have the peroxide react properly.
- the combination thereof in an economically advantageous way according to the present concepts is conventionally considered impossible.
- the (ZP) stage the following conditions may be utilized:
- the ozone dose is small, below 3 kg/adt and the purpose of the ozone is only to activate. Although disadvantageous conditions are used and a part of the ozone reacts poorly, this is insignificant, because the dose is small. Ozone is thus mainly used for the activation of the bleaching stage.
- the temperature in the ozone stage may be 50-80°C, preferably, for example, 60-70°C.
- the pH is 4-10, preferably about 6- 10.
- the dose in the P portion of the (ZP) stage is also small, usually less than 10 kg/adt. Normally about 3-7 kg/adt is sufficient.
- the temperature in the peroxide stage may be dropped to the range of 60-80°C, preferably to 70-80°C.
- the pH is 9-11, preferably about 10.
- the duration is about 1-6 hours.
- the pulp is washed and a filtrate S 3 is obtained.
- the filtrate S 3 may be used for the washing of pulp in connection with the earlier bleaching stages, discharged to the sewer, or led to the recovery of cooking chemicals.
- a vortex cleaner 66 and/or a screening plant may be added according to Fig. 3 to the last stage of the bleaching plant to precede the thickener/washer 68, which in this case does not have to be an MC® washer, as in the earlier embodiments.
- Pulp is diluted to the consistency range of about 0.5-1.5 % after the P-tower 140, when vortex cleaning or screening with a slotted screen is used. On the other hand, when screening with a perforated screen, a dilution to about 2-4% is usually sufficient.
- the pulp is thickened and washed - usually with a suction filter 68. Previously pulp had to be diluted after washing to a screening consistency and thickened again after screening to a medium consistency.
- FIG. 5 illustrates an oxygen delignification stage 80, which is followed by a two-stage washing 82. Pulp is transferred from the washing stage to the (ZT) stage 83, and from there via washing 84 to (EOP) stage 85, and from there via washing 86 to the (ZP) stage 87, which is followed by a washing stage 88.
- the amount of effluent, which is brought to the effluent clarification, discharge channel 90, is 0-5 m3/adt. Part of the effluent may alternatively be transferred to the manufacture of cooking chemicals, via discharge channel 92, to be used instead of fresh water. Thus the amount of effluent that must be treated is minimized.
- Fig. 5 may further be intensified by dividing the filtrates from the washer into two fractions with different pH according to Fig. 6.
- Fig. 6 utilizes the reference numbers of Fig. 5 with a preceding "1".
- the washers used in Fig. 6 are manufactured and marketed by A. Ahlstrom Corporation, and known as DRUM DISPLACERTM washers.
- the pulp for the last washer 188 comes from the alkali (ZP) stage.
- ZP alkali
- the first outwashed filtrate 1881 is clearly alkaline and the filtrate 1882 coming out later is less alkaline or even neutral, because water 1880 flowing to the last washer 188 is generally neutral or slightly acid.
- the pH of the filtrates may also be adjusted by adding acid or alkali to them before they are used again. In some cases it may, for example, be necessary to add alkali to the filtrates prior to their being brought to the brown stock washing or it may be necessary to add acid in order to maintain the pH low during the removal of the metals in the (ZT) stage (point 1840). It is possible that heavy metals are thickened again and attach to the fibers, if the pH increases during washing. Thus heavy metals are entrained to the P portion of the (ZP) stage following the Z portion and disturb the peroxide stage. Preferably the pH value is maintained less than 4, or at least maintained at 4, during the removal of heavy metals.
- the pH values of the filtrates are close to the pH values of the entering and exiting pulp, preferably closer to these than to each other.
- the present invention also includes a new method of arranging the screening subsequent to the pulp bleaching in such a way that a separate washing between the last washing stage and screening/vortex cleaning is unnecessary, but only dilution to screening/cleaning consistency.
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- Engineering & Computer Science (AREA)
- Wood Science & Technology (AREA)
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- Coloring Foods And Improving Nutritive Qualities (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
Description
- (ZT) refers to a bleaching stage with ozone, which also includes treatment of heavy metals and which stage is followed by washing and/or thickening,
- (EOP) refers to a bleaching stage with peroxide or oxygen and peroxide in alkali conditions and the stage is followed by washing and/or thickening,
- (ZP) refers to bleaching stage with ozone and peroxide without a between stage washing and which stage is followed by washing and/or thickening.
Stage | Chemical | consumption adt | Duration min. | Temperature °C |
Z | O3 | 0.5 | 2 | 40 - 50 |
E | O2 | 0.4 | 60 | 80 - 90 |
P | H2O2 | 1.5 | 180 | 80 - 90 |
MgSO4 | 0.4 | |||
Z | O3 | 0.1 | 2 | 70 |
P | H2O2 | 0.4 | 180 | 70 |
MgSO4 | 0.3 |
- HD-
tower 210 prior to the (ZT) stage, -
Drop leg 218 subsequent to the Z reactor, - Drop
leg 72 betweenwasher 222 and the (EOP) stage, - Drop
leg 74 betweenwasher 232 and the (ZP) stage.
- pH - incoming pulp
- 10
- pH - exiting pulp
- 7.5
- pH - filtrate I
- 9.5
- pH - filtrate II
- 8.0
Claims (18)
- A method of washing pulp in connection with bleaching, in which method the pulp is bleached in a first bleaching arrangement, washed in a first washer, bleached in a second bleaching arrangement, and washed in a second washer in such a manner that the washing liquid is recirculated from said second washer to said first washer countercurrent to the pulp flow, characterized in introducing washing liquid to said second washer for washing the pulp coming from said second bleaching arrangement, displacing with said washing liquid at least two different filtrates, collecting said at least two different filtrates separately, and using said at least two filtrates separately upstream of said second washer as washing liquids.
- A method as recited in claim 1, characterized in collecting from said second washer a first filtrate and a second filtrate, and introducing said first and said second filtrates as first and second washing liquids to said first washer.
- A method as recited in claim 2, characterized in that said second bleaching arrangement is a combined ZP-stage whereby said first filtrate from said second washer is alkaline and is introduced as a first washing liquid to said first washer.
- A method as recited in claim 1, characterized in collecting from said second washer a first filtrate and a second filtrate having different pH, and introducing said first and said second filtrates as second and first washing liquids, i.e. in opposite order to said first washer.
- A method as recited in claim 4, characterized in that said second bleaching arrangement is a peroxide bleaching stage whereby a first filtrate collected from said second washer is introduced into said first washer as the second/last washing liquid.
- A method as recited in claim 4, characterized in that said second bleaching arrangement is an ozone bleaching stage whereby a first filtrate collected from said second washer is introduced into said first washer as the second/last washing liquid.
- A method as recited in claim 1, characterized in having an additional bleaching arrangement and an additional washer upstream of said first bleaching arrangement.
- A method as recited in claim 7, characterized in receiving at least two different filtrates separately from said first washer, and introducing said at least two different filtrates separately to said additional washer for washing pulp coming from said additional bleaching arrangement.
- A method as recited in claim 1, characterized in that said washers are single-stage washers.
- A method as recited in claim 1, characterized in that said second bleaching arrangement includes a peroxide bleaching tower from where the pulp is introduced into said second washer.
- A method as recited in claim 10, characterized in that said second bleaching arrangement includes an ozone bleaching stage connected upstream of said peroxide bleaching tower.
- A method as recited in claim 1, characterized in that said first bleaching arrangement includes a peroxide bleaching tower
- A method as recited in claim 7, characterized in that said additional bleaching arrangement includes an ozone bleaching stage.
- A method as recited in claim 1, characterized in introducing fresh washing liquid to said second washer.
- A method as recited in claim 1, characterized in introducing said at least two filtrates in the same order to said first washer as washing liquids.
- A method as recited in claim 1, characterized in introducing said at least two filtrates in an opposite order to said first washer as washing liquids.
- A method as recited in claim 1, characterized in adjusting the pH of at least one of said filtrates by means of adding acid or alkali prior to introducing said filtrate as washing liquid to said first washer.
- A method as recited in claim 1, characterized in that said at least to filtrates have a different pH.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FI930954A FI93232C (en) | 1993-03-03 | 1993-03-03 | Method for bleaching pulp with chlorine-free chemicals |
FI930954 | 1993-03-03 | ||
EP93910051A EP0687321B1 (en) | 1993-03-03 | 1993-05-25 | Method of bleaching pulp with chlorine-free chemicals |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP93910051A Division EP0687321B1 (en) | 1993-03-03 | 1993-05-25 | Method of bleaching pulp with chlorine-free chemicals |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0884415A1 true EP0884415A1 (en) | 1998-12-16 |
EP0884415B1 EP0884415B1 (en) | 2002-11-20 |
Family
ID=8537491
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP93910051A Expired - Lifetime EP0687321B1 (en) | 1993-03-03 | 1993-05-25 | Method of bleaching pulp with chlorine-free chemicals |
EP98113684A Expired - Lifetime EP0884415B1 (en) | 1993-03-03 | 1993-05-25 | Method of washing pulp in connection with bleaching |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP93910051A Expired - Lifetime EP0687321B1 (en) | 1993-03-03 | 1993-05-25 | Method of bleaching pulp with chlorine-free chemicals |
Country Status (13)
Country | Link |
---|---|
EP (2) | EP0687321B1 (en) |
JP (1) | JP3276083B2 (en) |
AT (2) | ATE228181T1 (en) |
AU (1) | AU5370594A (en) |
BR (1) | BR9307858A (en) |
CA (1) | CA2157109C (en) |
DE (2) | DE69323566T2 (en) |
ES (2) | ES2130260T3 (en) |
FI (3) | FI93232C (en) |
NO (1) | NO953444L (en) |
PT (1) | PT884415E (en) |
RU (1) | RU2126471C1 (en) |
WO (1) | WO1994020673A1 (en) |
Families Citing this family (15)
Publication number | Priority date | Publication date | Assignee | Title |
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FI89516B (en) | 1989-05-10 | 1993-06-30 | Ahlstroem Oy | Foerfarande Foer blekning av cellulosamassa med Otson |
FI103818B (en) * | 1995-02-21 | 1999-09-30 | Ahlstrom Machinery Oy | Method for bleaching pulp |
US20080110584A1 (en) * | 2006-11-15 | 2008-05-15 | Caifang Yin | Bleaching process with at least one extraction stage |
FR2910027B1 (en) * | 2006-12-13 | 2009-11-06 | Itt Mfg Enterprises Inc | PROCESS FOR WHITENING CHEMICAL STRIPPING PASTES BY FINAL OZONE TREATMENT AT HIGH TEMPERATURE |
MX357819B (en) | 2009-05-28 | 2018-07-25 | Gp Cellulose Gmbh Star | Modified cellulose from chemical kraft fiber and methods of making and using the same. |
CN103703184B (en) | 2011-05-23 | 2016-09-07 | Gp纤维素股份有限公司 | There is the whiteness of improvement and the coniferous wood kraft fibers of brightness and production and preparation method thereof |
AU2013207797B2 (en) | 2012-01-12 | 2017-05-25 | Gp Cellulose Gmbh | A low viscosity kraft fiber having reduced yellowing properties and methods of making and using the same |
AU2013249725B2 (en) | 2012-04-18 | 2017-04-20 | Gp Cellulose Gmbh | The use of surfactant to treat pulp and improve the incorporation of kraft pulp into fiber for the production of viscose and other secondary fiber products |
JP6472758B2 (en) | 2013-02-08 | 2019-02-20 | ゲーペー ツェルローゼ ゲーエムベーハー | Softwood kraft fiber with improved α-cellulose content and its use in the production of chemical cellulose products |
AU2014229520B2 (en) | 2013-03-14 | 2017-09-21 | Gp Cellulose Gmbh | A method of making highly functional, low viscosity kraft fiber using an acidic bleaching sequence and a fiber made by the process |
MX357604B (en) | 2013-03-15 | 2018-07-16 | Gp Cellulose Gmbh | A low viscosity kraft fiber having an enhanced carboxyl content and methods of making and using the same. |
FR3007044B1 (en) * | 2013-06-13 | 2016-01-15 | Air Liquide | PROCESS FOR TREATING CHEMICAL PAPER PASTES BY OZONE TREATMENT IN THE PRESENCE OF MAGNESIUM IONS |
AT515152B1 (en) * | 2013-11-26 | 2015-12-15 | Chemiefaser Lenzing Ag | A process for pretreating recovered cotton fibers for use in the manufacture of regenerated cellulose moldings |
CA3040734A1 (en) | 2016-11-16 | 2018-05-24 | Gp Cellulose Gmbh | Modified cellulose from chemical fiber and methods of making and using the same |
SE545759C2 (en) * | 2022-06-20 | 2024-01-02 | Valmet Oy | Method for bleaching pulp from recycled textile material |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4310384A (en) * | 1979-01-11 | 1982-01-12 | Weyerhaeuser Company | Reducing chemical transfer between treatment stages |
US5116423A (en) * | 1986-03-20 | 1992-05-26 | A. Alhstrom Corporation | Apparatus for washing pulp |
EP0509981A1 (en) * | 1991-04-16 | 1992-10-21 | Kamyr, Inc. | Two stage pressure diffuser |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NO144711C (en) * | 1978-04-04 | 1981-10-21 | Myrens Verksted As | PROCEDURE FOR BLACKING OXYGEN-EQUIVALIZED CELLULOSE-containing OZONE |
DE69004492T3 (en) * | 1989-06-06 | 2001-11-15 | Eka Nobel Ab, Bohus | Process for bleaching pulps containing lignocellulose. |
AU636173B2 (en) * | 1989-10-30 | 1993-04-22 | Lenzing Aktiengesellschaft | Method for the chlorine-free bleaching of pulps |
SE468355B (en) * | 1991-04-30 | 1992-12-21 | Eka Nobel Ab | CHEMISTRY OF CHEMICAL MASS THROUGH TREATMENT WITH COMPLEX PICTURES AND OZONE |
AT400153B (en) * | 1991-05-02 | 1995-10-25 | Voest Alpine Ind Anlagen | METHOD FOR BLEACHING MATERIALS CONTAINING XYLAN AND LIGNOCELLULOSE |
-
1993
- 1993-03-03 FI FI930954A patent/FI93232C/en active
- 1993-05-25 WO PCT/FI1993/000222 patent/WO1994020673A1/en active IP Right Grant
- 1993-05-25 CA CA002157109A patent/CA2157109C/en not_active Expired - Fee Related
- 1993-05-25 EP EP93910051A patent/EP0687321B1/en not_active Expired - Lifetime
- 1993-05-25 AU AU53705/94A patent/AU5370594A/en not_active Abandoned
- 1993-05-25 EP EP98113684A patent/EP0884415B1/en not_active Expired - Lifetime
- 1993-05-25 PT PT98113684T patent/PT884415E/en unknown
- 1993-05-25 DE DE69323566T patent/DE69323566T2/en not_active Expired - Fee Related
- 1993-05-25 ES ES93910051T patent/ES2130260T3/en not_active Expired - Lifetime
- 1993-05-25 AT AT98113684T patent/ATE228181T1/en not_active IP Right Cessation
- 1993-05-25 JP JP51962394A patent/JP3276083B2/en not_active Expired - Fee Related
- 1993-05-25 AT AT93910051T patent/ATE176808T1/en not_active IP Right Cessation
- 1993-05-25 ES ES98113684T patent/ES2186948T3/en not_active Expired - Lifetime
- 1993-05-25 BR BR9307858A patent/BR9307858A/en not_active IP Right Cessation
- 1993-05-25 RU RU95122814A patent/RU2126471C1/en active
- 1993-05-25 DE DE69332508T patent/DE69332508T2/en not_active Expired - Fee Related
- 1993-09-15 FI FI934036A patent/FI98223B/en not_active IP Right Cessation
-
1995
- 1995-08-30 FI FI954093A patent/FI954093A/en not_active IP Right Cessation
- 1995-09-01 NO NO953444A patent/NO953444L/en unknown
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4310384A (en) * | 1979-01-11 | 1982-01-12 | Weyerhaeuser Company | Reducing chemical transfer between treatment stages |
US5116423A (en) * | 1986-03-20 | 1992-05-26 | A. Alhstrom Corporation | Apparatus for washing pulp |
EP0509981A1 (en) * | 1991-04-16 | 1992-10-21 | Kamyr, Inc. | Two stage pressure diffuser |
Also Published As
Publication number | Publication date |
---|---|
EP0687321A1 (en) | 1995-12-20 |
ES2130260T3 (en) | 1999-07-01 |
FI98223B (en) | 1997-01-31 |
NO953444D0 (en) | 1995-09-01 |
CA2157109C (en) | 2002-09-03 |
FI934036A0 (en) | 1993-09-15 |
PT884415E (en) | 2003-03-31 |
RU2126471C1 (en) | 1999-02-20 |
FI930954A (en) | 1994-09-04 |
FI930954A0 (en) | 1993-03-03 |
AU5370594A (en) | 1994-09-26 |
JPH08509781A (en) | 1996-10-15 |
FI954093A (en) | 1995-10-17 |
EP0884415B1 (en) | 2002-11-20 |
EP0687321B1 (en) | 1999-02-17 |
ATE176808T1 (en) | 1999-03-15 |
ES2186948T3 (en) | 2003-05-16 |
ATE228181T1 (en) | 2002-12-15 |
NO953444L (en) | 1995-10-19 |
WO1994020673A1 (en) | 1994-09-15 |
FI93232C (en) | 1995-03-10 |
DE69323566T2 (en) | 1999-07-15 |
CA2157109A1 (en) | 1994-09-15 |
BR9307858A (en) | 1996-02-27 |
JP3276083B2 (en) | 2002-04-22 |
DE69323566D1 (en) | 1999-03-25 |
FI934036A (en) | 1994-09-04 |
DE69332508D1 (en) | 2003-01-02 |
DE69332508T2 (en) | 2003-07-03 |
FI954093A0 (en) | 1995-08-30 |
FI93232B (en) | 1994-11-30 |
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