MECHANICAL PULPING: Fibre and fines quality development in pilot scale high and low consistency refining of ATMP

Gorski, Dmitri; Mörseburg, Kathrin; Olson, James A.; Luukkonen, Antti

doi:10.3183/npprj-2012-27-05-p872-881

Cited by 14 publications

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“…The tensile index depends on the number of inter-fiber connections (SIXTA, 2006;GORSKI et al, 2012). The highest average length and the lowest production of fines in cellulosic pulp from seven-year-old trees guaranteed greater connectivity between the fibers and a higher tensile index (FU et al, 2015).…”

Section: Resultsmentioning

confidence: 99%

PULP PRODUCED WITH WOOD FROM Eucalyptus TREES DAMAGED BY WIND

Zanuncio

Carvalho

Carneiro

et al. 2016

CERNE

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Wind may damage eucalyptus trees, especially 24 months after planting, which can reduce wood fiber quality and hinder pulp production. The objective of this study was to evaluate the use of these materials in mixtures with wood from seven-yearold trees to produce pulp. Bleached pulp was produced using 100, 95, 85, 75 and 0% wood from seven-year-old eucalyptus trees, related to cutting age. Wood from two-yearold trees, when trees are most susceptible to damage by wind, completed each treatment. A 5 cm thick disc was taken from breast height (1.3m) on each tree for anatomical and ultrastructural characterization. The seven-year-old wood had lower vessel frequency and fibers with a longer length, higher cell wall fraction, higher modulus of elasticity and hardness, and a lower microfibril angle. Pulp refining decreased the opacity and specific volume, increased air resistance and improved mechanical properties. The addition of two-year-old wood to produce pulp reduced the mechanical properties and opacity, and increased the air resistance of the paper. The proportion of two-year-old wood that can be used in pulp production varied with the clone, parameter, and refining level. However, the pulp produced with 5% wood from two-year-old trees and 95% wood from sevenyear-old trees was similar to that with 100% seven-year-old wood. Therefore, 5% twoyear-old wood can be used to produce pulp without quality losses. PRODUÇÃO DE POLPA CELULÓSICA COM MADEIRA DE ÁRVORES DEEucalyptus DANIFICADAS PELO VENTO RESUMO: Árvores de eucalipto de rápido crescimento podem ser danificadas por ventos, principalmente 24 meses após o plantio, mas a baixa qualidade das fibras dessa madeira dificulta a produção de polpa celulósica. O objetivo deste estudo foi avaliar a utilização destes materiais para a fabricação de polpa celulósica em misturas com madeira de árvores de sete anos de idade. Polpa celulósica branqueada foi produzida com 100, 95, 85, 75 e 0% de madeira de árvores de dois clones de Eucalyptus grandis x Eucalyptus urophylla com sete anos de idade, relacionada com a idade de corte. Madeira de árvores de dois anos de idade, mais susceptíveis a danos por ventos, foi utilizada para completar cada tratamento. Um disco de espessura de 5 cm foi retirado na altura do peito (1,3 m) em cada árvore para a caracterização anatômica e ultra-estrutural. As árvores com sete anos apresentaram maior frequência de vasos, fibras com maior comprimento, fração parede, módulo de elasticidade e dureza e menor ângulo microfibrilar. O refino nas polpas diminuiu a opacidade e o volume específico e aumentou a resistência a passagem do ar e as propriedades mecânicas. A adição de madeira de dois anos de idade na produção de polpa celulósica reduziu a resistência mecânica e opacidade e aumentou a resistência à passagem de ar. A proporção da madeira de dois anos de idade, que pode ser utilizado na produção de polpa celulósica variou com o clone, parâmetro avaliado e intensidade do refino. No entanto, a polpa celulósica produzida com 5% de madeira de do...

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Section: Resultsmentioning

confidence: 99%

PULP PRODUCED WITH WOOD FROM Eucalyptus TREES DAMAGED BY WIND

Zanuncio

Carvalho

Carneiro

et al. 2016

CERNE

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“…The cross-sectional dimensions of fibers decrease with HC refining (Kure 1999) but remain unchanged or even increase with LC refining perhaps due to internal delamination and swelling (Gorski et al, 2012a). The distribution of fiber fractions from the two processes also differs considerably.…”

Section: Introductionmentioning

confidence: 98%

“…The advanced thermomechanical pulp (ATMP) process gives rise to pulps with similar properties to those produced by a traditional TMP process, but the energy input is significantly lower (Gorski et al 2011a(Gorski et al , 2012cJohansson et al 2011). The low-consistency (LC) refining of primary ATMP further reduces the total energy requirement: ~300 kW h odt -1 less energy is needed to achieve the target pulp and paper properties by secondary LC refining compared with the secondary high-consistency (HC) refining of primary ATMP (Gorski et al, 2012a).…”

Section: Introductionmentioning

confidence: 98%

“…During LC refining, the long fiber fraction (R30) is lowered and the middle fraction (P30/R100) is elevated (Gorski et al 2012b). LC-refined fibers are more flexible but have a smaller external surface area compared with HC-refined fibers (Gorski et al, 2012a). The interpretation is that LC refining creates less external fibrillation (EF) and more internal delamination compared with HC refining, although the characteristic of the fibrillation has not been studied.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of fiber development in high- and low-consistency refining of primary mechanical pulp

Fernando¹,

Gorski²,

Sabourin

et al. 2013

Holzforschung

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Primary refined softwood was subjected to highconsistency (HC) or low-consistency (LC) secondary refining, and the nature of the development of the internal and external fiber microstructure and ultrastructure has been compared. The primary refining of mixed softwood as a raw material was performed in pilot scale by the advanced thermomechanical pulp process. The study was aiming at the comparative characterization of LC and HC pulps at the fiber level when produced with similar and well-characterized handsheet properties. The formerly described Simons' staining method was applied. A significant degree of fiber wall delamination/internal fibrillation (D/IF) was observed during both LC and HC refining. Both the energy input and the refining consistency had a significant impact on elevating the degree of fiber wall D/IF. The statistical evaluation of internal fiber development indicated that the fiber populations in LC-and HC-refined pulps had a similar degree of fiber wall D/IF despite having a large difference in refining energy input (420 kW h odt -1 ), confirming that D/IF was promoted more energyefficiently in LC than in HC refining. The characteristic of the external fiber development from HC and LC refining was very different. Secondary LC refining promoted fiber surfaces with ribbons of thin hairlike threads arising from the inner secondary S2 layer that occasionally developed along the whole fiber length. Broad sheet-and lamellaetype external fibrillation from the S2 was typical for HC refining, and these characteristics were rarely observed in the LC pulps. The mechanisms for LC and HC fiber development are proposed. The cell wall characteristics (internal and external) of the pulp fibers appear to govern most of the physical and optical properties in handsheets.

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“…They showed that refining modifies the surface chemistry and morphology of fibres, presumably by making structural changes in the fibre cell wall composition. Gorski et al (2012) proposed that, while HC refining resulted in a significant reduction in fibre wall thickness associated with fibre collapse and increase in external fibrillation, LC refining mainly generated structural changes, which may be seen in fibre straightening and increased flexibility. Extensive internal fibrillation of the straighter LC refined fibres appeared to have compensated for lower fines content and external fibrillation, producing well-bonded sheets with good tensile strength.…”

Section: Introductionmentioning

confidence: 99%

Merging Interstage Fractionation and Low Consistency Advantages During the TMP Refining Process: Part III – How Fibre Morphology Impacts Paper Properties

Lemrini¹,

Lanouette²,

Michaud³

2014

BioResources

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Fibre morphology and its evolution during refining and fractionation at low consistency were studied to understand the key relationships between the mechanical properties of paper and those of fibres. A broad analysis is presented on the physical and mechanical properties characterising the intrinsic morphological properties of fibres. The experimental refining process involved a primary stage at high consistency (HC), a fractionation stage with a small aperture basket, a low consistency (LC) refining stage, and a final high consistency refining (HCR) stage. The idea was to benefit from the pulp already being at low consistency following the screening step. Using a higher proportion of low consistency refining (LCR) tended to lower the tensile strength at 100 mL CSF, but some intermediate values did exhibit better responses to refining. Fractionation permits the use of LCR to retain fibre length and to develop additional long fibre bonding. The net gain remains even with energy reduction. It is believed, among other things, that a greater number or greater intensity of fibre-to-bar contacts would help increase internal delamination of the fibre structure.

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MECHANICAL PULPING: Fibre and fines quality development in pilot scale high and low consistency refining of ATMP

Cited by 14 publications

References 0 publications

PULP PRODUCED WITH WOOD FROM Eucalyptus TREES DAMAGED BY WIND

PULP PRODUCED WITH WOOD FROM Eucalyptus TREES DAMAGED BY WIND

Characterization of fiber development in high- and low-consistency refining of primary mechanical pulp

Merging Interstage Fractionation and Low Consistency Advantages During the TMP Refining Process: Part III – How Fibre Morphology Impacts Paper Properties

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