WO2023235965A1 - Désilication et fabrication d'une pâte à papier non ligneuse chimico-mécanique à faible intensité de carbone et de co-produits - Google Patents

Désilication et fabrication d'une pâte à papier non ligneuse chimico-mécanique à faible intensité de carbone et de co-produits Download PDF

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Publication number
WO2023235965A1
WO2023235965A1 PCT/CA2023/050771 CA2023050771W WO2023235965A1 WO 2023235965 A1 WO2023235965 A1 WO 2023235965A1 CA 2023050771 W CA2023050771 W CA 2023050771W WO 2023235965 A1 WO2023235965 A1 WO 2023235965A1
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WO
WIPO (PCT)
Prior art keywords
feedstock
pulp
temperature
wood feedstock
wood
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Application number
PCT/CA2023/050771
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English (en)
Inventor
Douglas Mckenzie
Martin Pudlas
Michael Beattie
Original Assignee
Red Leaf Sustainable Ip Corp.
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 Red Leaf Sustainable Ip Corp. filed Critical Red Leaf Sustainable Ip Corp.
Publication of WO2023235965A1 publication Critical patent/WO2023235965A1/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
    • D21C3/00—Pulping cellulose-containing materials
    • D21C3/02—Pulping cellulose-containing materials with inorganic bases or alkaline reacting compounds, e.g. sulfate 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
    • D21C1/00—Pretreatment of the finely-divided materials before digesting
    • D21C1/06—Pretreatment of the finely-divided materials before digesting with alkaline reacting 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
    • D21C5/00—Other processes for obtaining cellulose, e.g. cooking cotton linters ; Processes characterised by the choice of cellulose-containing starting materials
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
    • D21H11/08—Mechanical or thermomechanical pulp
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
    • D21H11/12—Pulp from non-woody plants or crops, e.g. cotton, flax, straw, bagasse

Definitions

  • the present disclosure relates generally to pulp production and more particularly, to the production of pulp and other co-products from non-wood feedstock.
  • non-wood feedstock can be difficult to process compared to traditional wood-based feedstock for several reasons.
  • non-wood feedstock tends to have less uniformity (e.g., straw feedstock can be overly long) and lower bulk density compared to wood-based feedstock, which can result in plugging of equipment and operational losses.
  • non-wood feedstock tends to have elevated fines content, which can negatively impact pulp properties and decrease mill productivity due to pulp drainage limitations.
  • non-wood feedstock tends to have elevated silica content, which can foul process equipment and impair their efficiency. The elevated silica content also impairs the lignin precipitation process required to improve the treatability of the effluent (i.e.
  • the elevated levels of silica present in the process liquor can co-precipitate in a colloidal form, thereby impairing filtration and making lignin removal difficult).
  • the lignin precipitation process is further impaired by the presence of hemicellulose in byproduct streams (e.g., black liquor), which can contribute to the formation of hydrogels.
  • byproduct streams e.g., black liquor
  • pulp produced from non-wood feedstock using existing technologies tend to have slower drainage rates compared to traditional wood-based pulp.
  • the slower drainage rates would require the non-wood pulp to be processed with larger equipment.
  • Non-wood pulp also typically have lower tensile strength compared to wood-based pulp.
  • High kappa chemi-mechanical non-wood pulps typically have higher lignin content compared to low kappa chemical non-wood pulps.
  • the elevated lignin content and hornification i.e., the inhibited reswelling of pulp fibres after drying
  • One aspect relates to a method for producing pulp from non-wood feedstock.
  • the method comprises the steps of desilicating the non-wood feedstock to selectively remove silica therefrom, impregnating the desilicated non-wood feedstock to selectively separate lignin therefrom, mechanically refining the impregnated non-wood feedstock to obtain a pulp stream, performing oxygen-alkali treatment on the pulp stream to separate additional lignin from the pulp stream, and removing the separated lignin from the pulp stream.
  • the desilication step is performed at a first temperature.
  • the impregnation step is performed at a second temperature with an alkaline solution having low alkali charge.
  • the oxygen-alkali treatment is performed at a third temperature.
  • the first temperature is in the range of 50°C to 100°C.
  • the second temperature is in the range of 100°C to 130°C.
  • the third temperature is in the range of 95°C to 130°C. The second temperature may be higher than the first temperature. The third temperature may be lower than the second temperature. The third temperature may be higher than the first temperature.
  • the primary screen may have a first set of slots interspaced between a first set of rolls, with the width of each slot in the first set of slots defining a first internal roll opening.
  • the secondary screen may have a second set of slots interspaced between a second set of rolls, with the width of each slot in the second set of slots defining a second internal roll opening.
  • the first internal roll opening may be about 1 mm
  • the second internal roll opening may be about 2 mm.
  • the screened non-wood feedstock is washed before it is desilicated
  • Another aspect relates to a method for producing pulp from non-wood feedstock comprising the steps of chemically treating a stream of the non-wood feedstock with a first alkaline solution, performing oxygen-alkali treatment on the stream of desilicated non-wood feedstock, and removing the separated silica and the separated lignin from the stream to obtain the pulp.
  • the desilication is performed at a first temperature.
  • the delignification is performed at a second temperature. The second temperature may be higher than the first temperature.
  • FIG. 3 depicts exemplary supplementary processes that can be incorporated or combined with the FIG. 1 process to produce other bioproducts from non-wood feedstock.
  • the systems and processes may involve treating the non-wood feedstock with alkaline solutions and/or alkaline liquor in one or more steps.
  • alkaline solution is used herein to refer to a solution containing only inorganic dissolved solids of chemical compounds (e.g., Na 2 CO3, NaOH, KOH, etc.).
  • alkaline liquor is used herein to refer to a solution containing both inorganic dissolved solids of chemical compounds (e.g., Na 2 CO3, NaOH, KOH, etc.) and organic dissolved solids (e.g., lignin, cellulose, hemi-cellulose, etc.).
  • Process 10 begins with optional straw preparation step 20.
  • Straw preparation step 20 comprises separating fines 6 from straw feedstock 2 and removing the separated fines 6 as dry material.
  • straw feedstock 2 may be screened or otherwise passed through one or more layers of screens.
  • the fines 6 removed from straw feedstock 2 can be optionally converted into useful co-products, such as a pellet fuel product, in supplementary processes (e.g., see FIG. 3).
  • step 20 comprises pre-processing straw feedstock 2 before passing the pre-processed straw feed stock 2 through the screen(s).
  • the pre-processing of straw feedstock 2 may include one or more of de-stacking, de-twining and/or deconstructing straw bales to provide loose straws.
  • the loose straws may then be cut individually or in bulk to relatively uniform lengths.
  • the loose straws may be cut to a length in the range of about 40 mm to about 100 mm (e.g., 50 mm, in particular embodiments).
  • Long straw strands may cause operational problems in non-wood pulping operations. Accordingly, it can be desirable to cut long straw strands to more nominal lengths to mitigate such problems. Cutting long straw strands to more nominal lengths can reduce the variability in the final pulp product, increase bulk density of feedstock 2, and/or improve the reliability of the overall pulping process 10.
  • the pre-processed feedstock 2 is transferred to a screening system.
  • the pre-processed feedstock 2 may, for example, be transferred to the screening system through a conveyor belt system.
  • the conveyor belt system may include a detection system that will reject the pre-processed straw feedstock 2 if residual twines are present. If the pre-processed straw feedstock 2 is rejected by the detection system, it may be returned for further pre-processing before it is transferred to the screening system.
  • the screening system may include one or more layers or stages of screens.
  • Each layer of the screens may have openings that remove straw fines 6 from the feed stream of feedstock 2 (i.e. , straw fines 6 will be removed from feedstock 2 as they drop through the openings).
  • Each layer of the screens may have different sized openings.
  • the screening system may optionally include a dust collection system for collecting dust in feedstock 2.
  • the dust collection system may include dust hoods located at various transfer points for feedstock 2.
  • the dust hoods may be connected to one or more draft fans or the like.
  • the draft fan(s) may be operated to draw the dust into a baghouse, or the like, where the dust will be filtered out of the air.
  • the dust collection system can help prevent the build-up of straw dust and fines 6 in the plant for housekeeping and fire prevention purposes.
  • the screening system includes two levels of screens (i.e., a primary screen and a secondary screen).
  • Each level of the screens may include slots interspaced between rolls.
  • Each level of screens may be, for example, a pyramid roll screen.
  • Each level of the screens may be configured to sort feedstock 2 based on length or other dimensions into an accepted stream (e.g., stream with straws having lengths greater than a threshold length) and a rejected stream (e.g., stream with straw fines).
  • the screens may be configured, for example, by adjusting the size of the gaps between slots or spacing between the rolls.
  • the size of the gaps between the slots or spacing between the rolls may be referred to herein as Internal Roll Opening (I O).
  • the IRO may be adjusted before or during operation of the screening system. In particular embodiments, this feature makes it possible to optimize the screening process during operation. For example, the IRO may be varied to control the amount or size of fines 6 that are filtered out of feedstock 2.
  • the fines 6 at the initial level of screening will fall between the inter-roll slots onto, for example, a fines conveyor belt to enter the rejected stream, while the “overs” (i.e., straws having lengths greater than the threshold length) will be discharged from the initial level to one or more subsequent levels of the screens.
  • the one or more subsequent levels of screens may be configured to screen relatively larger fines 6 or fines 6 that would not have been screened out by the preceding level of screens.
  • the IRO of the first level of screens may be set at about ⁇ 1 mm and the IRO of the next or second level of screens may be set at about ⁇ 2 mm.
  • the relatively larger fines 6 at the second level of screening will fall between the inter-roll slots onto, for example, the fines conveyor belt, while the overs will be discharged from the second level of screens.
  • the fines 6 that are removed from the feed by the second level screen may be collected along with fines 6 that are removed by the first level screen.
  • the collected fines 6 may be stored or provided to a separate or supplementary systems for further processing.
  • the collected fines 6 may be transported to a straw pellet plant to produce biofuel pellets.
  • non-wood feedstock like straw feedstock 2 inherently have high concentrations of fines 6 that add little value to the pulp properties, it can be desirable to pre-process straw feedstock 2 in the manner described above during optional preparation step 20. By removing the fines 6 and/or straw dust from straw feedstock 2 as dry material, they can be more efficiently converted into value added co-products (e.g., biofuel pellets) that can be used, for example, to generate power.
  • co-products e.g., biofuel pellets
  • the accepted stream of straw feedstock 2 may pass through a weight scale before it is desilicated in step 25.
  • the weight scale may be configured to monitor the total mass flow rate of straw feedstock 2.
  • process 10 proceeds to step 25 where the accepted stream of feedstock 2 is treated with hot water or a chemical solution (e.g., an alkaline solution) to pre-filter or otherwise separate some of the silica 7 from the stream of feedstock 2.
  • a chemical solution e.g., an alkaline solution
  • the chemical treatment may be conducted for a period of ten to thirty minutes or more.
  • the stream of feedstock 2 is heated and chemically desilicated with compounds like sodium carbonate, sodium hydroxide, potassium hydroxide, or the like.
  • Feedstock 2 may also be treated with hot water without the addition of alkaline chemicals in step 25.
  • the compounds used in desilication step 25 can preferentially separate silica 7 from the stream of feedstock 2.
  • the chemical desilication of feedstock 2 is supplemented with mechanical desilication to provide a chemi-mechanical process in step 25.
  • desilication step 25 may comprise mechanically pulping the stream of feedstock 2 after it has been heated and chemically reacted (e.g., in alkaline solution) to mechanically separate more silica 7 from feedstock 2.
  • silica 7 Upon completion of desilication step 25, a relatively large amount of silica 7 will be dissolved in the alkaline desilication liquor and selectively removed from the stream of feedstock 2 as shown in FIG. 1.
  • the silica enriched filtrate i.e. , the liquor containing the dissolved silica
  • trace metals e.g., copper, iron, nickel, manganese, other transition metals, and the like
  • trace metals may also be separated from the stream of feedstock 2 and removed with the silica enriched filtrate upon completion of step 25.
  • impregnation step 30 is typically performed at a relatively low temperature (e.g., below 130° C) and with alkaline impregnation solution that has a relatively low alkali charge (e.g., low alkali soda). This prioritizes, at step 30, the selective removal of lignin 8A from feedstock 2 and the preparation of fibers for further processing downstream.
  • impregnation step 30 is typically performed under relatively higher pressures and/or at relatively higher temperatures. In some embodiments, impregnation step 30 is performed under pressures in the range of 1 bar to 11 bar.
  • impregnation step 30 may also result in the further separation and removal of trace metals (e.g., including but not limited to the transition metals of copper, iron, nickel, manganese, or the like) from feedstock 2.
  • trace metals e.g., including but not limited to the transition metals of copper, iron, nickel, manganese, or the like
  • delignification step 50 is typically conducted at lower temperatures, lower pressure levels (e.g., 2 bar to 7 bar), and lower consistency (e.g., 8% to 12%).
  • delignification step 50 is more selective in removing lignin over the other carbohydrates (e.g., cellulose and hemicellulose) that may remain in the nonwood fibers contained in feedstock 2.
  • Conducting delignification step 50 may, in some cases, help produce a final pulp product 4 that is brighter and/or has enhanced L*a*b* (i.e. , lightness, red/green value, blue/yellow value) color attributes.
  • process 10 proceeds to a post-processing step 60.
  • post-processing step 60 the lignin 8B separated from the pulp stream during step 50 is removed from the pulp stream.
  • step 60 comprises washing the pulp stream to remove the black liquor 8 containing lignin 8B from the pulp.
  • the ratio between the amount of lignin removed in step 30 and the amount of lignin removed in step 60 is about 2:1. For example, between 20% to 30% of the lignin originally found in feedstock 2 may be removed therefrom upon completion of step 50.
  • Lignin 8A, 8B removed from the pulp stream may be collected for use in one or more supplementary processes (e.g., supplementary process 80 in FIG. 3).
  • Post-processing step 60 may also include one or more stages of pulp screening.
  • Pulp screening may include the removal of fines from the pulp produced in step 50. The removal of fines, both primary and secondary, after the oxygen-alkali treatment improves the drainage rate of the pulp and reduces the surface area of the dewatering equipment required to process the pulp. This can lead to capital cost savings and improved pulp properties.
  • a high kappa pulp stream is typically obtained (e.g., a pulp stream having a kappa number that is greater than 30).
  • the kappa number is a dimensionless indicator of the bleachability of pulp.
  • the kappa number is approximately proportional to the residual lignin content of the pulp.
  • the kappa number may be defined as the product of a constant and percentage lignin content (e.g., Kappa Number ⁇ 6.578*L, where L is percentage lignin content).
  • the pulp stream has a kappa number that is greater than 30.
  • the pulp stream is dried in step 70 to form the final pulp product 4.
  • the pulp stream is moved to a high density storage before it is transported to a pulp drying and finishing area.
  • the pulp drying and finishing area may include one or more of the following: one or more drying sections (e.g., complete with a fan and cyclone separator), a pulp cooling stage, a discharge air scrubber, a gas burner, a reboiler, and a superheater.
  • the pulp stream may be fed from the high density storage to presses (e.g., twin roll presses (TRP)) that operate in parallel to dewater the pulp stream).
  • TRP twin roll presses
  • the dewatered pulp (e.g., pulp with greater than 48% consistency) from each TRP may be metered into a pressure-specifying sensory device (PSSD) by a rotary valve.
  • PSSD pressure-specifying sensory device
  • superheated steam can provide improvements in pulp properties of high kappa pulps.
  • superheated steam dried high kappa pulps are typically bulkier, stronger, tougher and stiffer than conventional flash dried pulps.
  • Superheated steam dried high kappa pulps can also have a more desirable color (e.g., a darker or richer color) compared to conventional flash dried pulps.
  • Process 10 may be implemented by various apparatuses which collectively form a chemi-mechanical system for producing pulp 4 from non-wood feedstock 2.
  • the system may be located or otherwise provided within a pulp production plant 200 (e.g., see FIG. 3).
  • Refiner 106 receives the desilicated and impregnated feedstock 2 from blow tank 104. Refiner 106 may be designed to perform step 40 in process 10. In the example embodiment illustrated in FIG. 2, refiner 106 also receives one or more alkali compounds to support the mechanical refining. The alkali compounds provided to refiner 106 may be the same compounds as those provided to impregnation tube 102, or they may be different compounds in other embodiments. Refiner 106 may be suitably configured to refine the impregnated feedstock 2 at medium to high consistency.
  • Dilution conveyor 108 is located downstream of refiner 106. Dilution conveyor 108 may be operated to transfer the refined pulp stream to oxygen alkali reactor 110 where step 50 is performed.
  • system 100 comprises a mixer 109 located between dilution conveyor 108 and reactor 110. Mixer 109 may be operated to mechanically mix the pulp stream with steam and/or oxygen, and deliver the mixture to reactor 110.
  • Downflow tower 112 is located downstream of oxygen alkali reactor 110. Downflow tower 112 is designed to act as a storage buffer between reactor 110 and additional screening and pulp washing apparatuses located further downstream (not shown). Downflow tower 112 includes a port for receiving a dilution filtrate and a chamber for mixing the dilution filtrate with the pulp. Since pulp can be difficult to pump at higher consistencies, downflow tower 112 can provide the additional reaction time needed to dilute the pulp to relatively lower consistencies before pumping the diluted pulp to the screens and pulp washing apparatuses.
  • a lignin precipitation process 80 is incorporated to convert black liquor 8 produced in process 10 to useful materials for electronics applications (e.g., supercapacitors) and/or chemical applications (e.g., chemical emulsions, chemical adhesives, etc.).
  • a thermal process 82 e.g., a hydrothermal liquefaction process
  • a pelletization process 84 is incorporated to produce biofuel pellets from fines 6.
  • a silica precipitation process 90 is incorporated to convert silica compounds (e.g., sodium silicate) produced in desilication step 25 to materials like silicic acid for use in additional high value products.

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  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
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Abstract

Des systèmes et des procédés sont décrits, pour produire une pâte à papier et d'autres bioproduits à partir d'une matière première non ligneuse. La matière première non ligneuse est criblée, désiliciée, imprégnée et affinée mécaniquement pour obtenir un courant de pâte à papier qui est ensuite soumis à un traitement à l'oxygène et aux alcalis. De la lignine et de la silice sont séparées du courant de pâte à papier pour obtenir la pâte à papier. Une désilication est effectuée à une première température avec de l'eau chaude, une solution alcaline et/ou une liqueur alcaline comprenant une faible charge d'alcalis pour séparer sélectivement la silice de la matière première non ligneuse. L'imprégnation peut être effectuée à une deuxième température avec une solution alcaline comprenant une faible charge d'alcalis pour séparer sélectivement la lignine de la matière première non ligneuse et préparer la pâte à papier à des fins de raffinage mécanique. Le traitement à l'oxygène et aux alcalis est effectué à une troisième température pour séparer plus de lignine du courant de pâte à papier.
PCT/CA2023/050771 2022-06-08 2023-06-06 Désilication et fabrication d'une pâte à papier non ligneuse chimico-mécanique à faible intensité de carbone et de co-produits WO2023235965A1 (fr)

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US202263350276P 2022-06-08 2022-06-08
US63/350,276 2022-06-08

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006098531A1 (fr) * 2005-03-17 2006-09-21 Hong, Hook Procede de fabrication de pate a papier mecanique semi-chimique a partir de tiges de mais
WO2009050338A1 (fr) * 2007-10-18 2009-04-23 Chempolis Oy Procédé pour améliorer les caractéristiques d'une pâte
WO2012054968A1 (fr) * 2010-10-26 2012-05-03 Zeo Ip Pty Ltd Composition de fibres de cellulose
US20190249363A1 (en) * 2016-10-11 2019-08-15 Clariant International Ltd. Method for extracting cellusose, hemicellulose and lignin from lignocellulose from plant biomass

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006098531A1 (fr) * 2005-03-17 2006-09-21 Hong, Hook Procede de fabrication de pate a papier mecanique semi-chimique a partir de tiges de mais
WO2009050338A1 (fr) * 2007-10-18 2009-04-23 Chempolis Oy Procédé pour améliorer les caractéristiques d'une pâte
WO2012054968A1 (fr) * 2010-10-26 2012-05-03 Zeo Ip Pty Ltd Composition de fibres de cellulose
US20190249363A1 (en) * 2016-10-11 2019-08-15 Clariant International Ltd. Method for extracting cellusose, hemicellulose and lignin from lignocellulose from plant biomass

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