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About 1,110 papers for “pulp refining”

Pulp disintegration and refining

Jean-Claude Roux · Cairn.info · 2026

While studying festive practices, historian Michel Vovelle identified “obstinate forms”—“formal structures capable of rising from their ashes in entirely different contexts.” Re-examining the criteria of such “obstinacy” allows us to update this 1980s concept. In its reformulated version, it connects with the notion of “latent custom” (Van Gennep), as well as with more established concepts such as “revitalization” and the “invention of tradition.”

Cited by 0

Quantifying the Pulp Refining Process

Richard J. Kerekes · Paper and Biomaterials · 2016

Pulp refining action is commonly described by one or more quantitative parameters to enable comparisons among refiners and optimization of individual refiners. Specific refining energy and refining intensity are the two most commonly used parameters. Both are energy-based, but recent work by this author has shown that additional parameters based on force are of benefit. This paper reviews the background and key aspects of this work.

Cited by 1Open access

Separate Refining Versus Mixed Refining of an “Easy” and “Hard” Refining Pulp

Richard M. Dennany · ScholarWorks - WMU (Western Michigan University) · 1959

A study of the strength development (mullen and tear) of mixtures of "easy" and "hard" refining pulp, in which the pulps were refined as a mixture with that in which they were separately refined, and then mixed, reveals that separate refining develops mullen to the same extent as does mixed refining, but that a higher tearing resistance at the same freeness and mullen can be obtained with separate refining.

Cited by 0Open access

Optimum strategies for pulp fractions refining

Patrick Huber, Bruno Carré, Saurabh Kumar et al. · Nordic Pulp & Paper Research Journal · 2018

Människor för vem casinospel till slut blir ett allvarligt problem, och denna artikel (alt. checklista) har sammanställts för dig som misstänker att du eventuellt lider av det som vanligtvis kallas för problematiskt spel spelberoende

Cited by 1

Chemical Modification of Pulp Refining Rates

G. G. Allan, Raja Aravamuthan, C. Christien et al. · 1985

It has long been known that certain simple chemicals can either accelerate or retard the rate of refining of pulps. Based on surface adsorption and osmotic pressure considerations, a hypothesis is proposed to provide a rationale for the behavior of these chemicals. The validity of this theory is demonstrated by the prediction of the effectiveness of a colorless, photostable chemical as a new beating aid and the verification of its performance as an accelerator for the refining of both chemical and mechanical pulp as well as secondary fibers.

Cited by 1Open access

Fibre Treatment Uniformity in Pulp Refining

Richard J. Kerekes, J. David McDonald · Paper and Biomaterials · 2018

This paper explores implications of previous work which suggested that pulp refining is achieved by a small number of impacts.As a consequence, the purpose of multiple bar crossings in refiners is to expose many fibres to a few effective cycles, not to impose many cycles on each fibre.Based on this postulate, tensile strength increase was found to be well described by a cumulative probability equation having two parameters: (a) number of bar crossings and (b) probability of a successful refining outcome at each crossing.In this paper, this concept further with additional refiner data was explored and the link between the probability term and measurable refiner variables was examined.By proposing the possibility, these two parameters may be a desirable alternative to specific energy and specific edge load for characterizing refining action.

Cited by 2Open access

ON THE REFINING OF WOOD PULP

Kazumoto Nakamura · Sen'iso kōgyō/Sen'iso kougyou · 1932

I. When bleached pulp is refined with the solution of CaO and Na2SO3, its α-cellulose content increases about 5%. The addition of NaOH in the cooking liquor, which consists of H2SO3 and Ca(HSO3)2, results the incrcase in α-cellulose content, but the addition of too much amount of NaOH decreases the yield. In bleaching of the refined pulp, it is most advantageous to carry it out at low temperature for short time with small quantity of bleaching powder. 2. The refining of unbleached pulp with the solution of CaO and Na2SO3, shows the best results. The refined chlorinated pulp is of the largest α-cellulose content and its the bleaching is most easy. The pulp, refined with NaOH solution, contains large amount of α-cellulose, but bleaching is most difficult, and if it is bleached to normal white, the cellulose is over bleached and its content decreases considerablly. The same results are obtained in the case of the solution of CaO and Na2SO3.

Cited by 0Open access

Fiber development in chemimechanical pulp refining

Gordon Broderick, Paris, Jean, J. L. Valade · PolyPublie (École Polytechnique de Montréal) · 1996

A second-order PLS model has been calculated to study the impact of two-stage refining on the standard hand-sheet properties of a chemimechanical pulp as well as the effect on fiber length distribution and whole pulp specific surface. For a certain ratio of specific energy to refining intensity in the first stage, specific surface can be developed without loss in average fiber length. Fine material is peeled primarily from the middle fiber fractions in the first stage of refining, when high energy levels are distributed over a large number of impacts. While increases in refining intensity may be substituted for increases in applied energy to maintain adequate fiber length, whole pulp specific surface benefits most from higher energy levels applied at low intensity. Minimizing energy requirements by increasing intensity in the first refining stage is therefore better suited to the stiffer fibers common to TMP pulping.

Cited by 3

Pulp Residence Time Influence on Refining Intensity and Pulp Quality

Karl Murton, Geoff Duffy, Stuart R Corson · 2002

Refining intensity was determined directly from measured residence times and energy data. However, the refining intensity did not correlate with pulp freeness and long fibre content (Bauer McNett). In contrast, the refiner plate gap correlated well with the pulp quality. It appears that the refining zone pulp pad characteristics play an important role in the energy transfer and thus development of pulp quality. Both the wood and fibre network properties should be considered to link the current intensity explanation to pulp quality. The residence time of pulp within a refining zone was measured for the key process conditions of energy input, production rate and refining consistency using a radioactive isotope. The measurements allow the pulp velocities within the refiner to be determined and thus enable a greater understanding of the refining mechanism(s). The chip/pulp residence time within a primary-stage TMP refiner were found to range from 3 to 15 seconds depending on the process conditions. For 'normal' TMP process conditions, pulp remained within the refining zone for approximately 0.5 seconds and within the refiner system (ribbon screw to blow valve) for approximately 3 seconds. Altering the process conditions demonstrated that: - Increased specific energy input and production rate both caused the refining zone residence time to increase. - Increased refining consistency did not change the refining zone residence time.

Cited by 3

REFINING OF PULP BY DILUTE NITRIC ACID

Yuichiro Sumi, Hiroshi Furuhashi · Sen i Gakkaishi · 1961

The application of dilute nitric acid on the refining of unbleached birch sulfite pulp was studied. Treatments with dilute nitric acid and then a hot alkaline solution were_??_recognized to be effective on the removal of resin without much degradation of cellulose, if the acid concentration is about one percent. Following conditions are recommended: acid concentration 1.0_??_1.2%, temperature 90_??_96°C, time 2_??_3 hours. As the nitric acid treatment makes resin and lignin of pulp easily soluble in a hot alkaline solution, the condition of hot alkaline treatment after the acid treatment may be decided by the degree of refining necessary to the refined pulp. The nitric acid refining is more effective than the ordinary refining in deresination.

Cited by 0Open access

MECHANISM OF HOT ALKALINE REFINING OF PULP

Yuichiro Sumi · Sen i Gakkaishi · 1962

The hot alkaline treatment of an amorphous cellulose and a crystalline cellulose were compared. The amorphous cellulose was prepared by saponification of acetyl cellulose in alcohol and the crystalline cellulose was prepared by acid hydrolysis. It was found that the crystalline region is degraded at pH values greater than 9, but not at pH values less than 9. This degradation of crystalline region appears to be caused by swelling. In a previous paper, it was reported that the degree of swelling of pulp fibers by hot alkaline solution varies with hydroxyl ion concentration and treating temperature. In the present study, it was found that the swelling is also influenced by thehydrating power of cation, i.e., the capacity of the cation for hydration. This observation can be explained as follows: The adsorbed hydroxyl ions attract cations which, because they are hydrated, force the chain molecules apart and thereby cause the fibers to swell.The mechanism of hot alkaline refining of pulp can be outlined as follows: The hot alkaline solution weakens the attractive forces between chains, and gradually penetrates into higher ordered regions. Throughout the process, all chain molecules which are contacted by the hot alkaline solution are attacked and degraded by hydroxyl ions. As illustrated in Fig. 6. the degradation of chain molecules proceeds from the reducing terminal sugar unit. Each successive degraded sugar unit leaves a reducing terminal unit on the chain molecule. Apparently most of the short chain molecules are completely degraded to monosaccharides by the above mechanism, but some chains seem to go into solution as polysaccharides or oligosaccharides.

Cited by 0Open access

Analysis and Characterization of a Pulp Refining System

Marcos Martinez, S. M. Wu · Journal of Engineering for Industry · 1982

A 12-in. disk refiner was modified and instrumented. The resulting refining system had the capabilities to control the plate gap separation and at the same time monitor the refining or output torque and plate clearance. With a prior knowledge of the refining operation, it was possible to derive an equation which provides a qualitative and quantitative evaluation of the refining process. This equation, called the Optimal Dynamic Equation (ODE), is based on the maximum power that can be transmitted to a packed pulp pad. The calculation of the ODE is accomplished by means of the cross-spectral estimates of the plate clearance and output torque obtained from the Dynamic Data System (DDS) stochastic vector models.

Cited by 0

Endoglucanase-assisted refining of bleached chemical birch pulp

Nuutinen, Inkeri · Aaltodoc (Aalto University) · 2021

Pulp refining is a prerequisite in the production of high-quality papers and boards while it is also one of the most energy consuming steps in the manufacturing process. Enzymatic refining has been identified as a potentially feasible and sustainable method for reducing the refining energy demand while preserving or even improving specific pulp and paper properties. However, enzymatic refining of birch pulp has not been addressed in the literature. The present work addresses this research gap and studies the applicability of endoglucanases for the refining of bleached birch sulfate pulp. The thesis includes a theoretical framework conducted as a literature acquisition and experimental laboratory-scale refining trials with four enzymes conducted as a case study in conditions corresponding to the conditions of the case paper machine.
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\nThe results of this study indicate that endoglucanase-assisted refining of birch pulp caused similar or even enhanced effects compared to corresponding studies conducted with softwoods in the literature. The most suitable treatments were determined to be enzyme IV with 40 g/t of pulp dose for quality improvements at an equal specific refining energy (SRE), enzyme III with 50 g/t of pulp dose for quality improvements at an equal drainage resistance, and enzyme I with 50 g/t of pulp dose for refining energy reductions and quality improvements at an equal tensile index. The most important enzyme-induced changes were the enhanced development of tensile index and internal bond strength, which took place without significantly impairing drainability, water retention value or tear index. These changes were determined to be mostly due to increased external fibrillation and modest fines content formation compared to the reference. A tensile index of 80 Nm/g was reached with 12.0–28.5% lower SRE when enzymes were utilized. At 60 kWh/t, the tensile index, internal bond strength and Gurley air resistance of paper were increased by 2.3–9.0%, 20.0–63.1%, and 30.9–341.2%, respectively, compared to the enzymatically untreated reference. However, since hardwoods require lower SRE compared to softwoods, the achieved absolute refining energy savings were lower in the case of birch compared to corresponding studies conducted with softwoods in the literature. The break-even price for enzyme I (50 g/t of pulp) was calculated to be 0.75€ per ton of pulp when refined to a tensile index of 80 Nm/g. With this price, the increased chemical costs could be fully covered with the savings generated from the reduced refining energy. The improved quality and the potential possibility to run paper machine with a higher velocity are additional benefits that could improve the feasibility.
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\nCurrently, the method is not net positive from the perspective of the case paper machine. The key issue with industrial-scale enzymatic refining was concluded to be the inadequate availability of well-controlled enzymes and their price. However, with the advances in protein engineering and enzyme production technologies, the availability of different enzyme preparations for refining applications is expected to improve and the price to decrease, which may help in the industrial-scale breakthrough of the method. Additionally, the tightening of environmental regulations may increase the interest in enzymatic refining in the future.

Cited by 0