EP0846199A1 - Treatment of pulp with chelating agent in at least two mixing steps without intermediate washing - Google Patents
Treatment of pulp with chelating agent in at least two mixing steps without intermediate washingInfo
- Publication number
- EP0846199A1 EP0846199A1 EP96928765A EP96928765A EP0846199A1 EP 0846199 A1 EP0846199 A1 EP 0846199A1 EP 96928765 A EP96928765 A EP 96928765A EP 96928765 A EP96928765 A EP 96928765A EP 0846199 A1 EP0846199 A1 EP 0846199A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- pulp
- chelating agent
- mixing steps
- mixing
- bleaching
- 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.)
- Granted
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
- D21C9/1026—Other features in bleaching processes
- D21C9/1042—Use of chelating agents
Definitions
- This invention relates to the bleaching of chemical pulp with chlor ⁇ ine-free bleaching chemicals.
- the invention more precisely, refers to the treatment of pulp by chelating agents in connection with the bleaching.
- Bleaching is carried out in most cases by first treating the paper- making pulp to be bleached with a chelating agent of the type EDTA or DTPA.
- the chelating agent has the object to remove from the pulp certain metal ions, particularly manganese, copper, iron a.o. which would affect the bleaching result negatively if they remain in the pulp.
- the chelating agent step ususlly is designated by the letter Q.
- the pulp is washed to eliminate the exposed metal ions from the pulp as completely as possible. Thereafter follows the bleaching, which normally is carried out with hydrogen peroxide, at times in combination with other bleaching steps and intermediate washing steps where ozone or peracids can be used. Hydrogen peroxide steps usually are designated by the letter P. According to a thumb rule, the more harmful metal ions are eliminated from the pulp in the Q-step, the more effective the subsequent bleaching will be.
- a method, at which the pulp is treated in a Q-step and thereafter in a P-step, usually is called the "Lignox"-method, as disclosed, for example, in EP-A-402 335.
- the original pulp normally is oxygen delignified to a relatively low kappa number prior to the QP-bleaching.
- a low kappa number implies that the obtainable maximum brightness increases and the bleaching chemical demand decreases.
- the QP-bleaching is carried out in mills most often in such a way, that the pulp first is passed through a pump, which pumps the pulp suspension through the treatment steps. Thereafter the chelating agent is admixed homogenously to the pulp in a mixer. The next step is a bleaching tower where the pulp without additional activation slowly passes through and where all remaining reaction takes place. The pulp finally is directed to a washing step where the exposed and complexed metal ions are washed out. The exposed liquid enriched on metal ions most often is discharged.
- the conditions normally applied in a Q-step are a temperature of 70-90 C, a stay-time of 1-2 hours, a pulp concentration of 10-14%, a pH of 5-7 and a charge of chelating agent of 1-3 kg/ton pulp.
- the Q-step from a strict bleaching point of view, actually is an unnec- cessary treatment step, because no increase in brightness takes place here.
- the Q-treatment is necessary for a successful chlor ⁇ ine-free bleaching, as appears from above. If the Q-step could be simplified without thereby reducing the efficiency of metal eliminat ⁇ ion, great savings could be made, because a complete bleaching step with bleaching tower is expensive.
- the present invention is directed to a solution of the aforesaid problems.
- the Q-step is made more efficient by eliminating the metals effectively at the same time as the Q-step is simplified, resulting in reduced investment costs in relation to a conventional Q-step.
- the invention is based on the surprising discovery that the efficiency of the Q-step is affected considerably less by increased reaction temperature than by increased retention time. This indicates, accord ⁇ ing to classic chemical kinetics, that the Q-step is controlled by diffusion and not by reaction. The Q-step, consequently, should be carried out so that diffusion is facilitated. If this is done effect ⁇ ively, the total retention time can thereby be reduced considerably.
- the best way of reducing the diffusion resistance is by decreasing the diffusion distance for active reactants and released reaction products. This is achieved on technical scale by effective mixing, preferably in a mixer.
- the retention time in the Q-step thus, can be reduced by repeated effective mixing.
- the number of mixing steps should be at least two, preferably at least three. For economic reasons, however, the number of mixing steps, and thereby the number of mixers, must be held on a reasonable level. A suitable number can be 2-4 steps.
- a cert ⁇ ain retention time between the mixing steps is of good use, but this time need not be long, because the diffusion rate without mixing still is much slower than what is obtainable by mixing, for example in a mixer.
- the stay-time between the mixing steps shall be short, less than 15 minutes, suitably less than 10 minutes, and preferably less than 5 minutes.
- the mixing steps should be carried out one after the other, without intermediate washing.
- the washing required for re ⁇ moving the metals from the pulp suspension shall be carried out after the last mixing step.
- the chelating agent preferably is of the type EDTA (ethylene diamine tetraacetic acid) or DTPA (diethylene triamine pentaacetic acid) , but other types of chelating agent can be used, for example NTA (nitrilo- triacetic acid) or DTPM, J (diethylene triamine pentamethylene phosphonic acid).
- the total amount of added chelating agent should be 0,5-5 kg/ t pulp (counted as pure chelating agent), preferably 1-3 kg/ t pulp.
- the entire charge of chelating agent can be added in the first mixing step, whereby subsequent mixing steps bring about only repeated mix ⁇ ing.
- the chelating agent can be added in several of the mixing steps.
- the charging then should be made substantially in the first step, and in subsequent steps the added amount should be less than 2 kg/ t pulp per step.
- the temperature in the mixing steps should be above 70 C and suitably above 80°C.
- a preferable temperature interval is 80-120°C.
- the pressure in the entire Q-step preferably should be 1-10 bar.
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Wood Science & Technology (AREA)
- Paper (AREA)
- Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)
- Cosmetics (AREA)
- Chemical Or Physical Treatment Of Fibers (AREA)
- Detergent Compositions (AREA)
Abstract
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SE9502962A SE504803C2 (en) | 1995-08-24 | 1995-08-24 | Treatment of pulp with complexing agents in at least two mixing steps without intermediate washing |
SE9502962 | 1995-08-24 | ||
PCT/SE1996/000996 WO1997008380A1 (en) | 1995-08-24 | 1996-08-09 | Treatment of pulp with chelating agent in at least two mixing steps without intermediate washing |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0846199A1 true EP0846199A1 (en) | 1998-06-10 |
EP0846199B1 EP0846199B1 (en) | 2001-01-24 |
Family
ID=20399294
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP96928765A Expired - Lifetime EP0846199B1 (en) | 1995-08-24 | 1996-08-09 | Treatment of pulp with chelating agent in at least two mixing steps without intermediate washing |
Country Status (11)
Country | Link |
---|---|
EP (1) | EP0846199B1 (en) |
AT (1) | ATE198916T1 (en) |
AU (1) | AU6839996A (en) |
BR (1) | BR9610199A (en) |
CA (1) | CA2229212A1 (en) |
DE (1) | DE69611680T2 (en) |
ES (1) | ES2153593T3 (en) |
NO (1) | NO980753L (en) |
PT (1) | PT846199E (en) |
SE (1) | SE504803C2 (en) |
WO (1) | WO1997008380A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9745700B2 (en) | 2008-06-20 | 2017-08-29 | International Paper Company | Composition and recording sheet with improved optical properties |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
SE508239C2 (en) * | 1997-01-03 | 1998-09-21 | Sunds Defibrator Ind Ab | Treatment of pulp with complexing agents in at least one mixing step, without the use of the bleaching tower |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
ATE97179T1 (en) * | 1989-06-06 | 1993-11-15 | Eka Nobel Ab | PROCESS FOR BLEACHING LIGNOCELLULOSE CONTAINING PULP. |
SE9201477L (en) * | 1992-05-11 | 1993-06-28 | Kamyr Ab | SEATING WHITE PILLOW WITHOUT USING CHLORIC CHEMICALS |
SE502665C2 (en) * | 1993-06-11 | 1995-12-04 | Kvaerner Pulping Tech | Methods and reactor for ozone bleaching |
SE501836C2 (en) * | 1993-09-21 | 1995-05-22 | Sunds Defibrator Ind Ab | Bleaching of chemical pulp whereby the pulp is treated with complexing agents before and after an ozone step |
-
1995
- 1995-08-24 SE SE9502962A patent/SE504803C2/en not_active IP Right Cessation
-
1996
- 1996-08-09 AU AU68399/96A patent/AU6839996A/en not_active Abandoned
- 1996-08-09 ES ES96928765T patent/ES2153593T3/en not_active Expired - Lifetime
- 1996-08-09 WO PCT/SE1996/000996 patent/WO1997008380A1/en active IP Right Grant
- 1996-08-09 CA CA002229212A patent/CA2229212A1/en not_active Abandoned
- 1996-08-09 BR BR9610199A patent/BR9610199A/en not_active Application Discontinuation
- 1996-08-09 EP EP96928765A patent/EP0846199B1/en not_active Expired - Lifetime
- 1996-08-09 AT AT96928765T patent/ATE198916T1/en not_active IP Right Cessation
- 1996-08-09 PT PT96928765T patent/PT846199E/en unknown
- 1996-08-09 DE DE69611680T patent/DE69611680T2/en not_active Expired - Fee Related
-
1998
- 1998-02-23 NO NO980753A patent/NO980753L/en not_active Application Discontinuation
Non-Patent Citations (1)
Title |
---|
See references of WO9708380A1 * |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9745700B2 (en) | 2008-06-20 | 2017-08-29 | International Paper Company | Composition and recording sheet with improved optical properties |
Also Published As
Publication number | Publication date |
---|---|
CA2229212A1 (en) | 1997-03-06 |
SE504803C2 (en) | 1997-04-28 |
NO980753D0 (en) | 1998-02-23 |
WO1997008380A1 (en) | 1997-03-06 |
DE69611680D1 (en) | 2001-03-01 |
SE9502962L (en) | 1997-02-25 |
ATE198916T1 (en) | 2001-02-15 |
AU6839996A (en) | 1997-03-19 |
DE69611680T2 (en) | 2001-05-10 |
NO980753L (en) | 1998-02-24 |
PT846199E (en) | 2001-06-29 |
EP0846199B1 (en) | 2001-01-24 |
SE9502962D0 (en) | 1995-08-24 |
ES2153593T3 (en) | 2001-03-01 |
BR9610199A (en) | 1998-08-04 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
CA2149648C (en) | Process for delignification of lignocellulose-containing pulp | |
EP0010543A1 (en) | Bleaching lignocellulose material with bleaching agents containing peroxide | |
EP0650541B1 (en) | Process for bleaching pulp in conjunction with adsorption of metals | |
JP3276083B2 (en) | Pulp bleaching with chlorine-free chemicals. | |
CA2168288C (en) | Bleaching compositions comprising sulfamates and borates or gluconates and processes | |
WO1996009434A1 (en) | Method of bleaching kraft pulp | |
EP0464110B1 (en) | Bleaching process for the production of high bright pulps | |
US4798652A (en) | Peroxide bleaching of mechanical pulps | |
EP0846199B1 (en) | Treatment of pulp with chelating agent in at least two mixing steps without intermediate washing | |
AU665461B2 (en) | Method of treating process water | |
AU726599B2 (en) | Treatment of pulp with a chelating agent without using a bleaching tower | |
AU686024B2 (en) | Treatment of chemical pulp with a chelating agent and an oxidizing agent in connection with bleaching | |
JP3360694B2 (en) | Delignification bleaching method of chemical pulp for papermaking. | |
EP0726980B1 (en) | A method of separating metal ions from pulp | |
CA2090338A1 (en) | Process for treatment of lignocellulosic pulp and apparatus for performance of the process | |
EP0847460A1 (en) | Method for preventing accumulation of metals in a closed pulp bleaching process | |
CA2219767A1 (en) | Treatment of pulp with chelating agent and subsequent bleaching at a ph value above 9 | |
WO1998014657A1 (en) | Oxidation of disturbing metal ions in bleaching processes | |
CA1328714C (en) | Peroxide bleaching of mechanical pulps |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
17P | Request for examination filed |
Effective date: 19980207 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): AT DE ES FI FR PT SE |
|
GRAG | Despatch of communication of intention to grant |
Free format text: ORIGINAL CODE: EPIDOS AGRA |
|
17Q | First examination report despatched |
Effective date: 20000221 |
|
GRAG | Despatch of communication of intention to grant |
Free format text: ORIGINAL CODE: EPIDOS AGRA |
|
GRAH | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOS IGRA |
|
GRAH | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOS IGRA |
|
RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: SUNDS DEFIBRATOR INDUSTRIES AKTIEBOLAG |
|
RAP1 | Party data changed (applicant data changed or rights of an application transferred) |
Owner name: VALMET FIBERTECH AKTIEBOLAG |
|
GRAA | (expected) grant |
Free format text: ORIGINAL CODE: 0009210 |
|
AK | Designated contracting states |
Kind code of ref document: B1 Designated state(s): AT DE ES FI FR PT SE |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: SE Free format text: THE PATENT HAS BEEN ANNULLED BY A DECISION OF A NATIONAL AUTHORITY Effective date: 20010124 |
|
REF | Corresponds to: |
Ref document number: 198916 Country of ref document: AT Date of ref document: 20010215 Kind code of ref document: T |
|
ET | Fr: translation filed | ||
REF | Corresponds to: |
Ref document number: 69611680 Country of ref document: DE Date of ref document: 20010301 |
|
REG | Reference to a national code |
Ref country code: ES Ref legal event code: FG2A Ref document number: 2153593 Country of ref document: ES Kind code of ref document: T3 |
|
REG | Reference to a national code |
Ref country code: PT Ref legal event code: SC4A Free format text: AVAILABILITY OF NATIONAL TRANSLATION Effective date: 20010329 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: PT Payment date: 20010725 Year of fee payment: 6 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: FR Payment date: 20010731 Year of fee payment: 6 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: DE Payment date: 20010816 Year of fee payment: 6 |
|
PLBE | No opposition filed within time limit |
Free format text: ORIGINAL CODE: 0009261 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT |
|
26N | No opposition filed | ||
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: PT Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20030228 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: DE Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20030301 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: FR Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20030430 |
|
REG | Reference to a national code |
Ref country code: FR Ref legal event code: ST |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: FI Payment date: 20030818 Year of fee payment: 8 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: AT Payment date: 20030819 Year of fee payment: 8 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: ES Payment date: 20030825 Year of fee payment: 8 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: FI Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20040809 Ref country code: AT Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20040809 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: ES Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20040810 |
|
REG | Reference to a national code |
Ref country code: ES Ref legal event code: FD2A Effective date: 20040810 |