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WO1997030207A1 - Procede de blanchiment de pate chimique - Google Patents

Procede de blanchiment de pate chimique Download PDF

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Publication number
WO1997030207A1
WO1997030207A1 PCT/FI1997/000105 FI9700105W WO9730207A1 WO 1997030207 A1 WO1997030207 A1 WO 1997030207A1 FI 9700105 W FI9700105 W FI 9700105W WO 9730207 A1 WO9730207 A1 WO 9730207A1
Authority
WO
WIPO (PCT)
Prior art keywords
bleaching
pulp
process according
acid
chelating
Prior art date
Application number
PCT/FI1997/000105
Other languages
English (en)
Inventor
Ilkka Renvall
Elias Suokas
Reijo Aksela
Aarto Paren
Original Assignee
Kemira Chemicals Oy
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 Kemira Chemicals Oy filed Critical Kemira Chemicals Oy
Priority to AU17972/97A priority Critical patent/AU1797297A/en
Publication of WO1997030207A1 publication Critical patent/WO1997030207A1/fr

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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
    • 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
    • D21C9/16—Bleaching ; Apparatus therefor with per compounds

Definitions

  • the invention relates to a process for the bleaching or de ⁇ lignification of chemical pulp, wherein the pulp is treated with an acid chemical and a chelating agent in order to bind into a chelate complex any heavy metals present in the pulp.
  • TCF total chlorine free
  • Usable bleaching processes also include bleaching with peroxy compounds (such as peracetic acid, caron acid, or mixtures of peracids), a peroxide-enhanced oxygen step, and a peroxide-enhanced oxygen-alkali step.
  • peroxy compounds such as peracetic acid, caron acid, or mixtures of peracids
  • Such bleaching steps are most commonly preceded by the binding of heavy metals.
  • the metals can be removed by an acid wash. This is often disadvantageous, since at least some of the sub ⁇ sequent bleaching steps are carried out in alkaline conditions. If heavy metals are removed at a low pH, it is necessary first to use an acid in order to reach a low pH and in the next step an alkali to neutralize the acid. Furthermore, the acid wash removes Mg and Ca ions, which are regarded as advantageous for bleaching. The acid wash may also reduce the strength of the pulp.
  • Peroxy compounds such as peracetic acid and hydrogen peroxide are highly susceptible to the catalytic action of heavy metals.
  • the applicant's WO application publications 95/35406, 95/35407 and 95/35408 describe transition-metal activated bleaching with peroxy compounds in acid conditions. The success of the bleaching presupposes the binding of heavy metals before the bleaching and/or during the bleaching.
  • heavy metals are bound by using agents which chelate metal ions, for example poly- aminocarboxylic acids.
  • agents which chelate metal ions for example poly- aminocarboxylic acids.
  • EDTA ethylene diamine tetra-acetic acid and its salts
  • DTPA diethylene triamine penta-acetic acid and its salts
  • the ions the most detrimental in terms of bleaching are man ⁇ ganese (Mn), iron (Fe) and copper (Cu). Also other heavy metals, such as chromium ions (Cr), etc., have a detrimental effect, both on the consumption of peroxy compounds and often on the bleaching result, by reducing, for example, the vis ⁇ cosity of the bleached pulp. Detrimental heavy metals originate in the pulp, the treatment waters and the pulp-treatment apparatus.
  • Effective chelating agents are often poorly biodegradable, as is DTPA, or are completely non-biodegradable, as is EDTA.
  • TCF bleaching has increased the use of the said chelating agents. Therefore interest has arisen in replacing poorly biodegradable chelating agents either in part or entire ⁇ ly with biodegradable chelating agents.
  • the bio ⁇ degradable chelating agents be preferably phosphorus-free and also contain as small an amount of nitrogen as possible.
  • chelating agent for example, biodegradable ethylene diamine disuccinic acid (EDDS) or 2,2'-i inodisuccinic acid (ISA) and their alkali metal salts, which are per se previously known as compounds.
  • EDDS biodegradable ethylene diamine disuccinic acid
  • ISA 2,2'-i inodisuccinic acid
  • the applicants have observed, surprisingly, that an equally good bleaching result is achieved even if a portion of the above-mentioned nitrogen-containing chelating agents is re ⁇ placed with biodegradable nitrogen-free chelating agents, such as conventional carboxylic acids, hydroxycarboxylic acids, polyhydroxycarboxylic acids and hydroxypolycarboxylic acids.
  • biodegradable nitrogen-free chelating agents such as conventional carboxylic acids, hydroxycarboxylic acids, polyhydroxycarboxylic acids and hydroxypolycarboxylic acids.
  • generally used effective chelating agents such as a inopolycarboxylic acids, e.g. DTPA and EDTA, may in part be replaced with nitrogen-free biodegradable compounds.
  • hydroxy ⁇ carboxylic acids can be used successfully as chelating agents in bleaching, together with nitrogen-containing chelating agents.
  • Hydroxycarboxylic acids do not bind heavy metals effec ⁇ tively. Instead, they chelate well calcium and magnesium.
  • citric acid has been used instead of phosphates in phosphate-free detergents and cleansing agents which must bind calcium and magnesium.
  • the usability of the chelating process according to the invention is specifically based on the joint effect of chelating agents of different types.
  • the most preferred pH in terms of chelating is approx. 5-5.5.
  • aminopolycarboxylic acids are replaced with the above-mentioned hydroxycarboxylic acids, the chelating can be carried out at a higher pH.
  • the usable pH range is pH 6-8, most preferably pH 6.5-7.5.
  • the procedure according to the invention is advantageous, since a nitrogen-containing chelating agent can in part be replaced with a biodegradable chelating agent which does not contain nitrogen. Most commonly the cooking is carried out in alkaline conditions. Since, when chelating agent mixtures according to the invention are used, the chelating can be carried out at a higher pH, less acid is needed for achieving a pH advantageous for the chelating. Also, when the chelating process described in the invention is used, less alkali is required for raising the pH to a level suitable for the alkaline peroxide step nor ⁇ mally following the chelating. The characteristics of the invention are stated in the accom ⁇ panying patent claims.
  • nitrogen-containing chelating agents may be replaced by compounds known per se, having the general Formula I
  • n 1-8, m is 0-2n, p is 0-n, g is 0-2,
  • R- ⁇ is COOH
  • R 2 is H, CH 2 OH or COOH.
  • carboxylic acids, hydroxycarboxylic acids, poly ⁇ hydroxycarboxylic acids and hydroxypolycarboxylic acids accord ⁇ ing to Formula I such as citric acid, tartaric acid, lactic acid, pimelic acid, glutamic acid, glucoheptonic acid, ascorbic acid, glycolic acid, glutaric acid, adipic acid, succinic acid or malonic acid, can be used as replacement chelating agents.
  • the process according to the invention can be used for all known chemical pulps. These include alkaline and neutral sul- fite pulps, soda pulps, sulfate pulps (kraft pulps) and oxygen- delignified (oxygen cooking) sulfate pulps. Furthermore, the process can be used in the bleaching of so-called organosolv pulps in which alcohols or organic acids have been used as the cooking solvent, for example Milox cooking in formic acid.
  • the chelating process according to the invention may also be used when polysulfides or, for example, anthraquinone, have/has been used in sulfate cooking.
  • the treatment can be carried out on pulp cooked from different fiber raw materials, such as softwood, hardwood or reed, straw or other raw material of vegetable origin.
  • the chelating process according to the invention can be used in the bleaching or delignification of pulp in acid conditions and/or as a pretreatment before the process steps described above.
  • the pH control of an acid chelating step can be carried out using conventional mineral acids, such as sulfuric acid, sulfur dioxide or an aqueous solution thereof, carbon dioxide, or organic acids such as formic acid and acetic acid.
  • mineral acids such as sulfuric acid, sulfur dioxide or an aqueous solution thereof, carbon dioxide, or organic acids such as formic acid and acetic acid.
  • nitrogen-containing phosphorus-free chelating agents are preferably used, whereby environmental problems due to phosphorus are avoided.
  • chelating agents include ethylenediamine-N,N'-disuccinic acid (EDDS) , its various isomers and its alkali metal salts, such as sodium and potassium salts, and its earth-alkali metal salts, such as calcium and magnesium salts, 2,2' -iminodisuccinic acid (ISA), its various isomers and its alkali metal salts, such as sodium and potassium salts, and its earth-alkali metal salts, such as calcium and magnesium salts.
  • EDDS ethylenediamine-N,N'-disuccinic acid
  • ISA 2,2' -iminodisuccinic acid
  • alkali metal salts such as sodium and potassium salts
  • earth-alkali metal salts such as calcium and magnesium salts.
  • Usable chelating agents also include, among polyaminocarboxylic acids, ethylene diamine tetra-acetic acid (EDTA) and its salts, and diethylene triamine penta-acetic acid (DTPA) and its salts.
  • EDTA ethylene diamine tetra-acetic acid
  • DTPA diethylene triamine penta-acetic acid
  • Chelating agents within the scope of the invention are those which in addition to nitrogen also contain phosphorus, such as polyaminomethylene phosphonic acids or biodegradable aminoalkane diphosphonic acids, the use of which in the bleaching of pulp is known per se from WO applica ⁇ tion publication 95/12029.
  • Some specific examples of these chelating agents are, among aminoalkane phosphonic acids, 4- morpholinomethylene-l,l-diphosphonic acid (MMDPA) and its salts and, among aminopolymethylene phosphonic acids, aminotri- methylene phosphonic acid and its salts, ethylene diamine tet- ra ethylene phosphonic acid and its salts, and diethylene tri- amine pentamethylene phosphonic acid (DTMPA) and its salts.
  • MMDPA 4- morpholinomethylene-l,l-diphosphonic acid
  • DTMPA diethylene tri- amine pentamethylene phosphonic acid
  • Na ⁇ DTPA stands for the pentasodium salt of DTPA
  • Na ⁇ EDTA stands for the tetrasodium salt of EDTA
  • H5DTPA stands for the acid form of DTPA.
  • the pH used will determine how the chelating agents are dissociated, i.e. in which form they actually appear in the treatment.
  • DTPA is usually dosed into softwood pulp in the chelating step at a rate of approx. 2 kg/tp. Chelating was clearly less when the DTPA dose was reduced from a rate of 2.0 kg/tp to a rate of 1.0 kg/tp at a pH of approx. 6.5.
  • Table 2 shows the results of washing experiments similar to those described in Example 1 when the chelating agent used was Na citrate or Na gluconate together with EDDS or ISA at a pH of 5.8-8.9.
  • chelating was carried out on the same pulp with DTPA at various doses at a pH of 6.5.
  • An oxygen-delignified pulp was chelated and bleached with an alkaline hydrogen peroxide.
  • the chelating agents used were DTPA alone or together with Na citrate or Na gluconate.
  • the results are compiled in Table 3.
  • the bleaching result can be evaluated on the basis of peroxide consumption, the brightness achieved, and the viscosity of the pulp.

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
  • Paper (AREA)

Abstract

La présente invention concerne un procédé de blanchiment ou de délignification de la pâte chimique consistant, au moyen d'un produit chimique à base d'oxygène à faire subir à la pâte un traitement au moyen d'un agent chélateur de façon à lier dans un complexe de chélates les éventuels métaux lourds présents dans la pâte. L'agent chélateur utilisé est constitué d'un agent de chélation azoté et d'un mélange de l'un ou de plusieurs des composés représentés dans la formule générale (I) suivante, à savoir R1CnHm(OH)p(COOH)qR2 dans laquelle n = 1 à 8, m = 0 à 2n, p =0 à n, q = 0 à 2, R1 est COOH et R2 est H, CH2OH ou COOH.
PCT/FI1997/000105 1996-02-19 1997-02-19 Procede de blanchiment de pate chimique WO1997030207A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU17972/97A AU1797297A (en) 1996-02-19 1997-02-19 Process for bleaching of chemical pulp

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI960755A FI115470B (fi) 1996-02-19 1996-02-19 Menetelmä kemiallisen selluloosamateriaalin käsittelemiseksi
FI960755 1996-02-19

Publications (1)

Publication Number Publication Date
WO1997030207A1 true WO1997030207A1 (fr) 1997-08-21

Family

ID=8545484

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI1997/000105 WO1997030207A1 (fr) 1996-02-19 1997-02-19 Procede de blanchiment de pate chimique

Country Status (3)

Country Link
AU (1) AU1797297A (fr)
FI (1) FI115470B (fr)
WO (1) WO1997030207A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6590120B1 (en) 1998-03-09 2003-07-08 Kemira Chemicals Oy Methods for the preparation of an N-bis-[2-(1,2-dicarboxy-ethoxy)-ethyl]amine derivative and products of the methods and their uses
WO2011098599A1 (fr) * 2010-02-12 2011-08-18 Dequest Ag Procédé pour le blanchiment de pâte à papier
US20140202646A1 (en) * 2013-01-23 2014-07-24 Buckman Laboratories International, Inc. Bleach Stabilizer Compositions And Methods
US8906199B2 (en) * 2007-11-02 2014-12-09 Innospec Limited Process for bleaching pulp
WO2015181442A1 (fr) * 2014-05-27 2015-12-03 Upm-Kymmene Corporation Procédé de réduction de la teneur en phosphore dans un effluent provenant d'un processus de production de pulpe

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0141355A1 (fr) * 1983-10-21 1985-05-15 Benckiser-Knapsack GmbH Procédé pour blanchir une pulpe de bois broyé
WO1988006202A1 (fr) * 1987-02-12 1988-08-25 Kubat Josef Methode amelioree de decoloration au peroxyde
GB2206903A (en) * 1987-06-26 1989-01-18 Sandoz Ltd Stabilisers for peroxide-containing bleaching liquors
WO1994003553A1 (fr) * 1992-08-01 1994-02-17 The Procter & Gamble Company Composition de blanchiment peroxy stabilisee a l'acide ethylenediamine-n,n'-disuccinique
DE19528843A1 (de) * 1995-08-04 1997-02-06 Cht R Beitlich Gmbh Verfahren zur Stabilisierung von alkalischen peroxidenthaltenden Bleichflotten für die Bleiche von Zellstoffen und anderen Faserstoffen

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0141355A1 (fr) * 1983-10-21 1985-05-15 Benckiser-Knapsack GmbH Procédé pour blanchir une pulpe de bois broyé
WO1988006202A1 (fr) * 1987-02-12 1988-08-25 Kubat Josef Methode amelioree de decoloration au peroxyde
GB2206903A (en) * 1987-06-26 1989-01-18 Sandoz Ltd Stabilisers for peroxide-containing bleaching liquors
WO1994003553A1 (fr) * 1992-08-01 1994-02-17 The Procter & Gamble Company Composition de blanchiment peroxy stabilisee a l'acide ethylenediamine-n,n'-disuccinique
DE19528843A1 (de) * 1995-08-04 1997-02-06 Cht R Beitlich Gmbh Verfahren zur Stabilisierung von alkalischen peroxidenthaltenden Bleichflotten für die Bleiche von Zellstoffen und anderen Faserstoffen
WO1997006303A1 (fr) * 1995-08-04 1997-02-20 Cht R. Beitlich Gmbh Procede de stabilisation de bains de blanchiment alcalins contenant des peroxydes pour le blanchiment de pates de cellulose et d'autres substances fibreuses

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6590120B1 (en) 1998-03-09 2003-07-08 Kemira Chemicals Oy Methods for the preparation of an N-bis-[2-(1,2-dicarboxy-ethoxy)-ethyl]amine derivative and products of the methods and their uses
US8906199B2 (en) * 2007-11-02 2014-12-09 Innospec Limited Process for bleaching pulp
WO2011098599A1 (fr) * 2010-02-12 2011-08-18 Dequest Ag Procédé pour le blanchiment de pâte à papier
US20140202646A1 (en) * 2013-01-23 2014-07-24 Buckman Laboratories International, Inc. Bleach Stabilizer Compositions And Methods
WO2015181442A1 (fr) * 2014-05-27 2015-12-03 Upm-Kymmene Corporation Procédé de réduction de la teneur en phosphore dans un effluent provenant d'un processus de production de pulpe

Also Published As

Publication number Publication date
FI960755L (fi) 1997-08-20
FI960755A0 (fi) 1996-02-19
AU1797297A (en) 1997-09-02
FI115470B (fi) 2005-05-13

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