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EP4428297A1 - Verfahren zur gewinnung von vollständig oxidierter weisslauge zur verwendung in der faserlinie eines kraftzellstoffverfahrens - Google Patents

Verfahren zur gewinnung von vollständig oxidierter weisslauge zur verwendung in der faserlinie eines kraftzellstoffverfahrens Download PDF

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Publication number
EP4428297A1
EP4428297A1 EP23160197.2A EP23160197A EP4428297A1 EP 4428297 A1 EP4428297 A1 EP 4428297A1 EP 23160197 A EP23160197 A EP 23160197A EP 4428297 A1 EP4428297 A1 EP 4428297A1
Authority
EP
European Patent Office
Prior art keywords
stages
white liquor
kraft pulp
oxygen
fully oxidized
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.)
Pending
Application number
EP23160197.2A
Other languages
English (en)
French (fr)
Inventor
Oliveira ARAUJO
Philippe Campo
Bruno Alban
Jukka ISOMETSA
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.)
Air Liquide SA
LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Original Assignee
Air Liquide SA
LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
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 Air Liquide SA, LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude filed Critical Air Liquide SA
Priority to EP23160197.2A priority Critical patent/EP4428297A1/de
Priority to CA3230672A priority patent/CA3230672A1/en
Priority to US18/597,787 priority patent/US20240301622A1/en
Publication of EP4428297A1 publication Critical patent/EP4428297A1/de
Pending legal-status Critical Current

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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
    • D21C11/00—Regeneration of pulp liquors or effluent waste waters
    • D21C11/0064—Aspects concerning the production and the treatment of green and white liquors, e.g. causticizing green liquor
    • D21C11/0071—Treatment of green or white liquors with gases, e.g. with carbon dioxide for carbonation; Expulsion of gaseous compounds, e.g. hydrogen sulfide, from these liquors by this treatment (stripping); Optional separation of solid compounds formed in the liquors by this treatment
    • 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
    • D21C11/00—Regeneration of pulp liquors or effluent waste waters
    • D21C11/12—Combustion of pulp liquors
    • 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
    • D21C3/00—Pulping cellulose-containing materials
    • D21C3/02—Pulping cellulose-containing materials with inorganic bases or alkaline reacting compounds, e.g. sulfate processes
    • D21C3/022—Pulping cellulose-containing materials with inorganic bases or alkaline reacting compounds, e.g. sulfate processes in presence of S-containing compounds
    • 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

Definitions

  • This application relates to a process to obtain fully oxidized white liquor comprising NaOH, Na 2 SO 4 , NaCO 3 , and traces of Na 2 S 2 O 3 for use in the fiberline of a Kraft pulp process.
  • the Kraft process is a process for the conversion of wood into wood pulp consisting of almost pure cellulose fibers. It entails treatment of wood chips with a mixture of sodium hydroxide (NaOH) and sodium sulfide (Na 2 S), known as white liquor, which breaks the bonds that link lignin to the cellulose.
  • NaOH sodium hydroxide
  • Na 2 S sodium sulfide
  • EP1345684B1 discloses a method for oxidizing a liquid contained in a reactor (1) that comprises means for introducing gas into the reactor and means for introducing liquid into the reactor, at least liquid evacuating means, at least gas evacuating means.
  • the liquid contains compounds to be oxidized and the oxidizing gas contains oxygen, where gas roof bleeding provides a predetermined partial pressure of the oxygen in the gaseous roof, the value of said partial pressure corresponding to a desired oxidizing rate for said compounds.
  • EP1345680B1 discloses an oxidizing method by wet process oxidation or ozonization of a liquid contained in a reactor.
  • the method is more particularly suitable for all oxidizing processes using large amounts of oxygen or ozone. It is in particular used for oxidizing paper-mill liquors.
  • the present application relates to a process to obtain fully oxidized white liquor for use in the fiberline of a Kraft pulp process comprising the following steps:
  • the white liquor is oxidized with 20 to 60 kg of O 2 /m 3 of white liquor.
  • the oxygen is used as pure oxygen or as a gas mixture comprising oxygen.
  • oxygen is used with a purity degree above 70% v/v.
  • the fully oxidized white liquor substitutes up to 100% of the amount of purchased NaOH used in the bleaching stages and/or alkaline extraction stages and/or delignification stages of the Kraft pulp process.
  • the oxidation step occurs at a temperature above 100°C, pressure above 1 barg, and the total Hydraulic Residence Time is at least 30 minutes.
  • up to 100% of the filtrates from washing steps after the bleaching stages and/or alkaline extraction stages are sent to the Wastewater Treatment Plant.
  • Companies in this technical field can benefit from a reduction of the high cost related to purchased NaOH by reusing process streams currently present in the Kraft pulp process to produce a solution comprising NaOH which can be used as a substitute for the pure product.
  • the present application relates to a process to obtain said solution, known as fully oxidized white liquor (FOWL), which comprises NaOH, Na 2 SO 4 , NaCO 3 and traces of Na 2 S 2 O 3 .
  • FOWL fully oxidized white liquor
  • the FOWL is obtained from the white liquor used in a Kraft pulp process.
  • the aim of this process is to produce a solution suitable to substitute purchased NaOH used in the alkaline steps of certain stages in the fiberline, such as the delignification stages and/or alkaline extraction stages and/or bleaching stages that use NaOH in certain steps, as well as purge non-process elements from the recovery circuit of the kraft pulp process by purging alkaline wash filtrates to a Wastewater Treatment Plant (WWTP).
  • WWTP Wastewater Treatment Plant
  • the FOWL produced by the presently disclosed process is also suitable to be used in bleaching stages that use hydrogen peroxide.
  • the oxygen used in the present process can be not only pure oxygen but also impure oxygen with purity > 70% O 2 v/v.
  • This impure oxygen can be produced in a PSA or VSA unit, but also can be the off-gas of an Ozone bleaching stage, which normally is above 700 O 2 v/v.
  • reaction (I) as well as reaction (II) proceed to their full extent and the presence of sulfide ions is undetectable by Ionic Chromatography. In this case the extent of conversion of total sulfur to sulfate ions expressed as sulphur should be above 900.
  • the product of this process can be called "Fully Oxidised White Liquor" and the quality is so good that it can be used as a substitute for the purchased NaOH used in the fiberline, including the stages using hydrogen peroxide, without any detectable difference from using the pure NaOH product.
  • FIG. 1 shows a general schematic representation of a Kraft pulp process including one embodiment of the process disclosed in the present application.
  • the present application relates to a process to obtain fully oxidized white liquor from the white liquor used in a Kraft pulp process.
  • the FOWL is suitable to be used in the alkaline stages of the fiberline of said Kraft pulp process, such as the bleaching stages, and/or alkaline extraction stages and/or the delignification stages that comprise alkaline steps.
  • FIG. 1 shows a general schematic representation of a Kraft pulp process comprising the process of the present application.
  • (A) represents the fiberline and
  • (B) represents the recovery line.
  • a fraction of the white liquor (2) is fed to at least one oxidation reactor (K) to produce FOWL (5) which is used in the delignification stages (H) and/or the bleaching stages (I) and/or alkaline extraction stages to partly or totally substitute purchased NaOH used in alkaline steps of these stages.
  • the resulting alkaline wash filtrate (6.1, 6.2) of the delignification stages (H) and/or bleaching stages (I) are fed back to an evaporation plant (E) in the recovery line (B) to return to the Kraft chemical recovery process (C).
  • the non-process elements (7.1) will be totally or partly purged to the WWTP through the wash step after the alkaline bleaching stages (I).
  • purchased NaOH is also known as fresh NaOH.
  • the process to obtain fully oxidized white liquor for use in the fiberline of a Kraft pulp process comprises the following steps:
  • white liquor is oxidized with 20 to 60 kg of O 2 /m 3 of white liquor.
  • the amount of alkaline filtrate (6.2) obtained in the bleaching stages (I) and/or alkaline extraction stages that is fed to the evaporation plant (E) varies according to the concentration of non-process elements.
  • the amount of alkaline filtrate (6.1) obtained in the delignification stages (H) that is fed to the evaporation plant (E) is 100% due to the high concentration of chemical oxygen demand (COD).
  • up to 100% of the fully oxidized white liquor (5) is fed to the bleaching stages (I) and/or alkaline extraction stages and/or the delignification stages (H).
  • oxygen is used in the process as pure oxygen or as a gas mixture comprising oxygen.
  • pure oxygen is considered an oxygen stream with a purity degree above 700 O 2 v/v.
  • the FOWL totally or partially substitutes up to 100% of the amount of purchased NaOH used in the delignification stages of the Kraft pulp process.
  • the FOWL substitutes up to 100% of the amount of purchased NaOH used in the bleaching stages and/or alkaline extraction stages of the Kraft pulp process.
  • the oxidation step of the process makes use of at least one oxidation reactor (K) .
  • a plurality of reactors can be used for the purpose of the present invention.
  • the FOWL produced is an aqueous solution comprising NaOH, Na 2 SO 4 , NaCO 3 and less than 5 g of Na 2 S 2 O 3 per liter of FOWL, in which the presence of sulfide ions is undetectable by Ionic Chromatography and the extent of conversion of total sulfur to sulfate ions is above 900.
  • the temperature is above 100°C
  • the pressure is above 1 barg
  • the total Hydraulic Residence Time (HRT) is at least 30 minutes.
  • the sodium makeup of the recovery line of the Kraft pulp process is done - solely or in part, i.e., up to 1000, - in the delignification stages (H) by using purchased NaOH.
  • the sodium makeup of the recovery line of the Kraft pulp process is done - solely or in part - in the recovery boiler (F) as Na 2 CO 3 and/or Na 2 SO 4 .
  • the non-process elements such as K + or Cl - but not exclusively, are purged from the recovery line through the use of the FOWL.
  • the totality or a fraction, i.e., up to 100% of the filtrates from washing steps after the bleaching stages and/or alkaline extraction stages are sent to the WWTP - thus discharging the recovery line from non-process elements.

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  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
  • Paper (AREA)
EP23160197.2A 2023-03-06 2023-03-06 Verfahren zur gewinnung von vollständig oxidierter weisslauge zur verwendung in der faserlinie eines kraftzellstoffverfahrens Pending EP4428297A1 (de)

Priority Applications (3)

Application Number Priority Date Filing Date Title
EP23160197.2A EP4428297A1 (de) 2023-03-06 2023-03-06 Verfahren zur gewinnung von vollständig oxidierter weisslauge zur verwendung in der faserlinie eines kraftzellstoffverfahrens
CA3230672A CA3230672A1 (en) 2023-03-06 2024-02-29 Process to obtain fully oxidized white liquor for use in the fiberline of a kraft pulp process
US18/597,787 US20240301622A1 (en) 2023-03-06 2024-03-06 Process to obtain fully oxidized white liquor for use in the fiberline of a kraft pulp process

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP23160197.2A EP4428297A1 (de) 2023-03-06 2023-03-06 Verfahren zur gewinnung von vollständig oxidierter weisslauge zur verwendung in der faserlinie eines kraftzellstoffverfahrens

Publications (1)

Publication Number Publication Date
EP4428297A1 true EP4428297A1 (de) 2024-09-11

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP23160197.2A Pending EP4428297A1 (de) 2023-03-06 2023-03-06 Verfahren zur gewinnung von vollständig oxidierter weisslauge zur verwendung in der faserlinie eines kraftzellstoffverfahrens

Country Status (3)

Country Link
US (1) US20240301622A1 (de)
EP (1) EP4428297A1 (de)
CA (1) CA3230672A1 (de)

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1043516A (en) * 1973-07-25 1978-12-05 Mo Och Domsjo Aktiebolag Method for producing oxidized white liquor
EP0543135A1 (de) * 1991-10-18 1993-05-26 Air Products And Chemicals, Inc. Selektive Oxydation von Weisslauge
US5352332A (en) * 1991-01-28 1994-10-04 Maples Gerald E Process for recycling bleach plant filtrate
EP0643163A2 (de) * 1993-08-16 1995-03-15 The Boc Group, Inc. Verfahren zur Herstellung von oxydierter Weisslauge
WO2000047812A1 (en) * 1999-02-15 2000-08-17 Kiram Ab Process for oxygen pulping of lignocellulosic material and recovery of pulping chemicals
EP1345680B1 (de) 2000-12-20 2004-10-27 L'AIR LIQUIDE, Société Anonyme à Directoire et Conseil de Surveillance pour l'Etude et l'Exploitation des nassoxydations- oder ozonierungsverfahren
EP1345684B1 (de) 2000-12-20 2012-05-09 L'AIR LIQUIDE, Société Anonyme pour l'Etude et l'Exploitation des Procédés Georges Claude Verbesserungen bei oxidationsverfahren durch sauerstofftransfer in einem flüssigen medium in einem reaktor unter druck
WO2020165504A1 (en) * 2019-02-13 2020-08-20 Metsä Fibre Oy A method of replacing sodium losses in a pulp mill, a method of producing bleached cellulosic pulp, and a system
WO2021006798A1 (en) * 2019-07-05 2021-01-14 Kiram Ab Method for dissolving pulp from recycled textile material

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5374333A (en) * 1992-07-30 1994-12-20 Kamyr, Inc. Method for minimizing pulp mill effluents
SE514825C2 (sv) * 1999-09-16 2001-04-30 Aga Ab Oxygendelignifiering av cellulosamassa med oxiderad vitlut som alkalikälla
DE102020002446A1 (de) * 2020-04-23 2021-10-28 Messer Austria Gmbh Verfahren und Vorrichtung zur Weißlaugenoxidation

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1043516A (en) * 1973-07-25 1978-12-05 Mo Och Domsjo Aktiebolag Method for producing oxidized white liquor
US5352332A (en) * 1991-01-28 1994-10-04 Maples Gerald E Process for recycling bleach plant filtrate
EP0543135A1 (de) * 1991-10-18 1993-05-26 Air Products And Chemicals, Inc. Selektive Oxydation von Weisslauge
EP0643163A2 (de) * 1993-08-16 1995-03-15 The Boc Group, Inc. Verfahren zur Herstellung von oxydierter Weisslauge
WO2000047812A1 (en) * 1999-02-15 2000-08-17 Kiram Ab Process for oxygen pulping of lignocellulosic material and recovery of pulping chemicals
EP1345680B1 (de) 2000-12-20 2004-10-27 L'AIR LIQUIDE, Société Anonyme à Directoire et Conseil de Surveillance pour l'Etude et l'Exploitation des nassoxydations- oder ozonierungsverfahren
EP1345684B1 (de) 2000-12-20 2012-05-09 L'AIR LIQUIDE, Société Anonyme pour l'Etude et l'Exploitation des Procédés Georges Claude Verbesserungen bei oxidationsverfahren durch sauerstofftransfer in einem flüssigen medium in einem reaktor unter druck
WO2020165504A1 (en) * 2019-02-13 2020-08-20 Metsä Fibre Oy A method of replacing sodium losses in a pulp mill, a method of producing bleached cellulosic pulp, and a system
WO2021006798A1 (en) * 2019-07-05 2021-01-14 Kiram Ab Method for dissolving pulp from recycled textile material

Also Published As

Publication number Publication date
CA3230672A1 (en) 2025-06-27
US20240301622A1 (en) 2024-09-12

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