EP0720675A1 - Chlorine-free bleaching of chemical pulp involving a two stage treatment with chelating agent - Google Patents

Chlorine-free bleaching of chemical pulp involving a two stage treatment with chelating agent

Info

Publication number
EP0720675A1
EP0720675A1 EP94928521A EP94928521A EP0720675A1 EP 0720675 A1 EP0720675 A1 EP 0720675A1 EP 94928521 A EP94928521 A EP 94928521A EP 94928521 A EP94928521 A EP 94928521A EP 0720675 A1 EP0720675 A1 EP 0720675A1
Authority
EP
European Patent Office
Prior art keywords
pulp
bleaching
chelating agent
ozone
treated
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.)
Ceased
Application number
EP94928521A
Other languages
German (de)
English (en)
French (fr)
Inventor
M Rten Dahl
Solveig Nord N
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Valmet AB
Original Assignee
Sunds Defibrator Industries AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sunds Defibrator Industries AB filed Critical Sunds Defibrator Industries AB
Publication of EP0720675A1 publication Critical patent/EP0720675A1/en
Ceased legal-status Critical Current

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
    • 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

  • This invention relates to the bleaching of lignocellulose- -containing fiber material in the form of chemical pulp without using chloric bleaching agents.
  • the invention more precisely, relates to ozone bleaching of the pulp and sub ⁇ sequent peroxide bleaching.
  • the pulp is first treated with a chelating agent, for example DTPA or EDTA.
  • a chelating agent for example DTPA or EDTA.
  • metal ions are solved out of the pulp and are removed by dewatering the pulp prior to the ozone bleaching.
  • the pulp bleached with ozone still contains metals, which partially are absorbed on the fibers and partially solved in surrounding liquid. These metals must be removed for being able to bleach with peroxide in a subsequent step.
  • a treatment with chelat ⁇ ing agent is carried out at a pulp concentration of 1-10% for 1-60 minutes at a temperature of 20-70°C and a pH value of 2-5.
  • the pulp is thereafter dewatered and bleached with ozone. After the ozone bleaching the pulp is washed and dewatered, whereafter a peroxide bleaching takes place.
  • an additional treatment with chelating agent is carried out after the washing and de ⁇ watering. This treatment with chelating agent usually is carried out for 30-120 minutes at 60-90°C. The pulp must thereafter again be washed and dewatered prior to the peroxide bleaching.
  • FIG. 1 is an example of a flow chart for a method accord ⁇ ing to the invention.
  • Fig. 2 is a diagram showing the brightness as a function of the hydroperoxide charge, for known methods and, resp. , for a method according to the invention.
  • chemical pulp first is fed to a first chelating step 10 for treatment with EDTA or DTPA.
  • the pulp concentration should be 1-10% and the treatment be carried out for 1-60 minutes, preferably 5-30 minutes.
  • the temperature should be 20-70°C, preferably 20-40°C, and the pH value 2-5.
  • the pulp is washed and dewatered, for example in a washing press 11, for the removal of solved metal ions.
  • the pulp is directed therefrom to an ozone step 12 for ozone bleaching.
  • the pulp is diluted to a concentration of 1-10% and fed to a second chelating step 13.
  • chelating agent preferably DTPA or EDTA
  • the amount of charged DTPA or EDTA preferably can be up to 0,5 kg/ton pulp.
  • washing and dewatering is carried out to a concentration of 8-40% in a second washing step 14, whereafter the pulp is directed to a peroxide step 15 for peroxide bleaching.
  • the pulp can be bleached to a brightness exceeding 83% ISO.
  • Curve 1 relates to a conventional method with peroxide bleaching after the ozone-bleached pulp is only washed and dewatered .
  • Curve 2 relates to peroxide bleaching of ozone-bleached pulp, which in known manner had been washed, dewatered, treated with chelating agent and again be washed and dewater ⁇ ed prior to the peroxide bleaching.
  • Curve 3 relates to a method according to the invention.

Landscapes

  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
  • Paper (AREA)
EP94928521A 1993-09-21 1994-08-22 Chlorine-free bleaching of chemical pulp involving a two stage treatment with chelating agent Ceased EP0720675A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
SE9303066A SE501836C2 (sv) 1993-09-21 1993-09-21 Blekning av kemisk massa varvid massan behandlas med komplexbildare före och efter ett ozonsteg
SE9303066 1993-09-21
PCT/SE1994/000758 WO1995008666A1 (en) 1993-09-21 1994-08-22 Chlorine-free bleaching of chemical pulp involving a two stage treatment with chelating agent

Publications (1)

Publication Number Publication Date
EP0720675A1 true EP0720675A1 (en) 1996-07-10

Family

ID=20391160

Family Applications (1)

Application Number Title Priority Date Filing Date
EP94928521A Ceased EP0720675A1 (en) 1993-09-21 1994-08-22 Chlorine-free bleaching of chemical pulp involving a two stage treatment with chelating agent

Country Status (9)

Country Link
EP (1) EP0720675A1 (sv)
JP (1) JPH09503028A (sv)
AU (1) AU7792394A (sv)
BR (1) BR9407555A (sv)
CA (1) CA2168445A1 (sv)
FI (1) FI961279A (sv)
NO (1) NO961139D0 (sv)
SE (1) SE501836C2 (sv)
WO (1) WO1995008666A1 (sv)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE504803C2 (sv) * 1995-08-24 1997-04-28 Sunds Defibrator Ind Ab Behandling av massa med komplexbildare i minst två blandningssteg utan mellanliggande tvätt
SE508239C2 (sv) * 1997-01-03 1998-09-21 Sunds Defibrator Ind Ab Behandling av massa med komplexbildare i minst ett blandningssteg, utan användning av blektorn
CN102587186B (zh) * 2012-03-20 2015-03-11 昆明理工大学 一种大龙竹化学浆的漂白方法
RU2634586C1 (ru) * 2016-08-01 2017-10-31 федеральное государственное бюджетное образовательное учреждение высшего образования "Пермский национальный исследовательский политехнический университет" Способ отбелки лиственной сульфатной целлюлозы

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002517173A (ja) * 1991-01-03 2002-06-11 ユニオン キャンプ パテント ホウルディング インコーポレイテッド 塩素を使用しないリグノセルロースパルプの漂白法
SE468355B (sv) * 1991-04-30 1992-12-21 Eka Nobel Ab Blekning av kemisk massa genom behandling med komplexbildare och ozon

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9508666A1 *

Also Published As

Publication number Publication date
WO1995008666A1 (en) 1995-03-30
BR9407555A (pt) 1996-12-31
NO961139L (no) 1996-03-20
SE9303066L (sv) 1995-03-22
SE501836C2 (sv) 1995-05-22
SE9303066D0 (sv) 1993-09-21
CA2168445A1 (en) 1995-03-30
AU7792394A (en) 1995-04-10
FI961279A0 (sv) 1996-03-20
JPH09503028A (ja) 1997-03-25
NO961139D0 (no) 1996-03-20
FI961279A (sv) 1996-03-20

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