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External fibrillation of wood pulp, TAPPI Journal June 2023
ABSTRACT: Pulp refining produces external fibrillation consisting of fibrils tethered to fiber surfaces, in addition to loose fibrils and fines. Both contribute to a larger bonding area that increases paper strength, but tethered fibrils have less likelihood of being washed out during papermaking. This study postulates the mechanism by which refining produces external fibrillation and the optimum conditions for doing so.The postulated mechanism is surface abrasion during sliding of fibers in refiner gaps. External fibrillation occurs when forces are great enough to partially dislodge fibrils from fiber surfaces, but not large enough to break the fibrils. The refining intensities to achieve these forces were determined by a mathematical model and experiments using a laboratory disc refiner. The optimum intensities in terms of specific edge load (SEL) for chemical pulps were about 0.1 J/m for hardwoods and 1.0 J/m for softwoods. An extension of this study suggested that abrasion may also account for most of the energy consumed in the mechanical pulping process.
Journal articles
Magazine articles
Evaluating the effect of recovery boiler operation on green liquor dregs concentration using multivariate analysis, TAPPI Journal June 2023
ABSTRACT: Poor settling and filterability of green liquor dregs has been a persistent problem in many kraft pulp mills. While the concentration and settling/filtering behaviors of dregs are expected to be related to how black liquor is burned in recovery boilers, the effect of boiler operation is not well understood. A systematic study was conducted to examine how recovery boiler operation may affect the dregs concentration in the raw green liquor (RGL) at three kraft pulp mills using SIMCA, a multivariate data analysis (MVDA) program. Daily average boiler operating data from three kraft mills were analyzed over a 3-year period. Results of both principal component analysis (PCA) and partial least squares regression (PLS) suggest that the main boiler operations contributing to high dregs concentrations in RGL are low liquor firing load, low bed temperature, poor char burning, and unstable char bed.
Potassium Kraft Pulping: Possibility or Necessity, 1996 Minimum Effluent Mills Symposium Proceedings
Potassium Kraft Pulping: Possibility or Necessity, 1996 Minimum Effluent Mills Symposium Proceedings
Duplex Stainless Steel: An Effective Material for Use in Kraft Liquor Applications, 2001 Engineering / Finishing & Converting Conference Proceedings
Duplex Stainless Steel: An Effective Material for Use in Kraft Liquor Applications, 2001 Engineering / Finishing & Converting Conference Proceedings
Economics of Introducing Kenaf Fibers as a Complementary Fiber Source in Existing Wood Pulp Mills, 1998 Pulping Conference Proceedings
Economics of Introducing Kenaf Fibers as a Complementary Fiber Source in Existing Wood Pulp Mills, 1998 Pulping Conference Proceedings
Role of pH and Fe (III) in Delignification with Distilled Peracetic Acid, 1998 Pulping Conference Proceedings
Role of pH and Fe (III) in Delignification with Distilled Peracetic Acid, 1998 Pulping Conference Proceedings
Kraft Pulping Integrated with Mild Alkaline Pre-Extraction of Southern Mixed Hardwoods, 2008 Engineering, Pulping and Environmental Conference
Kraft Pulping Integrated with Mild Alkaline Pre-Extraction of Southern Mixed Hardwoods, 2008 Engineering, Pulping and Environmental Conference
Liquid absorption and evaporation in porous coating structures studied by near-infrared spectroscopy, 2010 TAPPI Advanced Coating Fundamentals Symposium
Liquid absorption and evaporation in porous coating structures studied by near-infrared spectroscopy, 2010 TAPPI Advanced Coating Fundamentals Symposium
Journal articles
Magazine articles
Wheat straw as an alternative pulp fiber, TAPPI Journal December 2024
Author: Peter W. Hart | TAPPI J. 19(1): 41(2020) - ABSTRACT: The desire to market sustainable packaging materials has led to an interest in the use of various fiber types as a raw material. It has been suggested that the use of annual crops for partial replacement of wood fiber would result in more sustainable products. Several life cycle analyses (LCA) have been performed to evaluate these claims. These LCAs provided conflicting and contradictory results because of the local conditions and the specific pulping processes investigated. Selected LCAs are reviewed and the underlying reasons for these conflicting results are analyzed.
Journal articles
Effect of pulp refining on thixotropy of cellulose fiber suspensions, TAPPI Journal September 2025
ABSTRACT: This paper presents results on the thixotropic behavior of low-consistency bleached eucalyptus fiber suspensions that had been mechanically treated. The pulps were refined in a PFI mill at different numbers of revolutions (0, 3000, and 6000) to study the effect of refining intensity on the viscosity time-response of fiber suspensions. In steady rheological tests, all the suspensions exhibited shear thinning behavior and no significant differences were observed after mechanical treatment. Stepwise experiments showed that viscosity continuously increased with time when shear rate was suddenly reduced. Additionally, a delay in time evolution of viscosity was observed as the pulp was more refined. A stretched exponential model was fitted to the experimental results of viscosity.