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A new method of studying the fundamental mechanisms involved in pigment liberation from recycle papers, TAPPI Journal October 2022
ABSTRACT: Deinking flotation is the most efficient and widely used method of removing ink particles from printed papers to improve the recyclability. A prerequisite for successful deinking flotation is detachment of pigments from paper fibers, a subprocess known as liberation. The degree of liberation is usually determined via hyperwashing tests, which are costly and time consuming. Furthermore, they provide no information on the fundamental mechanisms controlling liberation. In the present work, we developed a new method in which ?-potentials of the particles in a pulp are measured and analyzed. If pigments are not liberated from paper fibers, a frequency distribution plot gives a single peak, while two peaks appear when they are liberated. One can readily determine the degrees of liberation from the peak positions and peak heights. In addition, the ?-potential data can be used to construct disjoining pressure isotherms using the DLVO theory that are useful to better understand the fundamental mechanisms involved and the roles of different reagents used to improve pigment liberation.
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Combatting lime kiln ringing problems at the Arauco Constitución mill, TAPPI Journal July 2020
ABSTRACT: The lime kiln at the Arauco Constitución mill experienced severe ringing problems requiring it to be shut down for ring removal every 3 to 6 months. The mill controlled the problems by blasting ring deposits off during operation with its existing industrial shotgun and a newly installed Cardox liquid carbon dioxide (CO2) cartridge system. Various ring blasting procedures were tested to determine the optimum ring location and thickness to blast; the optimum depth to insert the CO2 cartridge into the kiln; and the most effective blasting frequency and sequence to employ. The best strategy was found to be the weekly blasting operation that alternated between the liquid CO2 cartridge and the industrial shotgun, with the CO2 cartridge inserted into the ring mass, 20 cm (8 in.) away from the refractory brick surface, and the shotgun aimed at rings at about 28 m (92 ft) from the kiln discharge end. With each blasting event removing considerably more rings than before, it takes a longer time for rings to rebuild, allowing the kiln to run continuously between annual maintenance shutdowns with only a few short (< 4 h) downtimes for ring removal. This substantially reduces the costs associated with ring removal and lime replacement during unscheduled shutdowns.
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Case study: Paper mill power plant optimization—balancing steam venting with mill demand, TAPPI Journal June 2020
ABSTRACT: Most Power departments are tasked with generating steam to support mill wide operations, generate electricity, and reduce operating costs. To accomplish these tasks, power boilers generate high pressure steam that is reduced to intermediate and low pressures for process utilization in the mill by means of steam turbine generator extraction or pressure reducing valves. The most economical method to reduce steam pressure is the use of steam turbine generators, as electricity is generated from the steam when it is reduced in pressure. Electricity that is produced by these generators provides a substantial financial benefit and helps offset overall operational costs. To achieve tangible financial gains, the mill must evaluate the overall cost of steam production and the price of electricity.The current work provides a case study of power plant optimization that evaluated electricity production and steam production costs balanced with mill steam demand. Process and cost optimization led to a significant reduc-tion in low pressure steam venting, resulting in reduced fuel consumption and reduced operating cost.
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Fate of phosphorus in the recovery cycle of the kraft pulping process, TAPPI Journal March 2020
ABSTRACT: The accumulation of nonprocess elements in the recovery cycle is a common problem for kraft pulp mills trying to reduce their water closure or to utilize biofuels in their lime kiln. Nonprocess elements such as magnesium (Mg), manganese (Mn), silicon (Si), aluminum (Al), and phosphorus (P) enter the recovery cycle via wood, make-up chemicals, lime rock, biofuels, and process water. The main purge point for these elements is green liquor dregs and lime mud. If not purged, these elements can cause operational problems for the mill. Phosphorus reacts with calcium oxide (CaO) in the lime during slaking; as a result, part of the lime is unavailable for slaking reactions. The first part of this project, through laboratory work, identified rhenanite (NaCa(PO4)) as the form of P in the lime cycle and showed the negative effect of P on the availability of the lime. The second part of this project involved field studies and performing a mass balance for P at a Canadian kraft pulp mill.
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Effects of a PFI refiner’s operational parameters on the swellability of recycled fiber, TAPPI Journal May 2020
ABSTRACT: This paper presents data on the effects of operational parameters (number of revolutions, linear pressure, and gap) of the PFI refiner on the swellability of recycled fiber, which was characterized by water retention value (WRV). The results showed that the increase of recycled fiber’s WRV was proportional to the number of revolutions and the linear pressure, but inversely proportional to the gap. The mathematical relation between these parameters and the fiber WRV could be described by an empirical model for gaps greater than 0.1 mm. Scanning electron microscopic images of fiber morphology showed that the basic framework of fibers could be maintained with the gap greater than 0.1 mm, but was destroyed with smaller gaps. This model provides a technical reference for quantitative control of refining treatment and an effective method for improving recycled fiber quality.
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Perfluoroalkyl and polyfluoroalkyl substances (PFAS) — Fibrous substrates, TAPPI Journal September 2023
ABSTRACT: Perfluoroalkyl and polyfluoroalkyl substances (PFAS) have been implemented during the finishing process of textiles such as upholstery, clothing, personal protective equipment, and sports gear to provide water resistance. Currently, PFAS are still present at quantifiable levels in consumer products and food, even though many companies have started to phase out PFAS treatment with non-toxic water repellant replacements given the possible detrimental health effects suggested by current research. This paper is a detailed review that focuses on how PFAS are implemented in textile production and sources of PFAS contamination during chemical treatments. This review also addresses current legislation on PFAS emissions and trade regulations to decrease exposure of consumers due to toxicokinetics and mechanisms of action through-out the body that are still not well understood. This paper includes a literature review on possible PFAS related health conditions shown from past research and contains suggested toxicity levels, exposure routes, duration, and pathways detailed to the best of our ability.
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Characterizing rheological behavior and fluidization of highly refined furnishes, TAPPI Journal April 2024
ABSTRACT: In this work, highly refined softwood bleached kraft pulp (SWBKP) furnishes, referred to here as XFC, were studied from the perspective of fiber suspension handling in processing. The rheology of the furnishes was studied with a rotational rheometer using a non-standard flow geometry to understand the viscosity development at different consistencies and the impact of temperature. For fluidization analysis during pipe flow, two optical methods were implemented; namely, optical coherence tomography (OCT) and high-speed video (HSV) imaging. The OCT was used to determine the small-scale floc structures near the pipe wall where the shear stress is highest, and the HSV imaging was applied for observing flow instabilities and XFC suspension uniformity at the pipe scale. All these issues can be significant in deciding the minimum flow rate required for a process pipe to get sufficient fluidization of XFC suspensions.
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Editorial: TAPPI Journal Best Research Paper for 2023 focuses on black liquor concentration using graphene oxide membranes, TAPPI Journal February 2024
ABSTRACT: TAPPI and the TAPPI Journal (TJ) Editorial Board would like congratulate the authors of the 2023 TAPPI Journal Best Research Paper Award and Honghi Tran Prize: Sam Rae, Ella V. Richards, Max Kleiman-Lynch, Brent D. Keller, and Brandon I. Macdonald. Their paper, “Pilot scale black liquor concentration using pressure driven membrane separation,” appeared on p. 223 of the April 2023 issue. This kraft recovery cycle research was recognized by the TAPPI Journal Editorial Board for its innovation, creativity, scientific merit, and clear expression of ideas.
Journal articles
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Quantification of hardwood black liquor contamination in pine black liquor, TAPPI Journal February 2024
ABSTRACT: The presence of hardwood black liquor contamination in pine black liquor can negatively impact brownstock washer and evaporator operation, as well as reduce soap separation and yield. It is also believed to negatively impact commercial kraft lignin production. It was desired to develop a method of quantitatively determining the amount of low-level hardwood liquor contamination in pine black liquor. A method employing pyrolysis-gas chromatography mass spectrometry (py-GCMS) was developed to perform the desired measurement. Laboratory cooks with carefully controlled blends of pine and hardwood chips were prepared, and the resulting liquor was measured using this technique. Additionally, samples of pine and hardwood black liquors were blended in known quantities and analyzed. All these samples were submitted as blind samples. The resulting analysis suggests the py-GCMS method was able to accurately determine the level of hardwood contamination between 1% to 10% hardwood liquor using a low-level calibration curve prepared with coniferyl alcohol and sinapyl alcohol as standards.
Journal articles
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Editoral: Investing in the future: Writing and peer-reviewing for TAPPI Journal, TAPPI Journal July 2024
ABSTRACT: Those who actively participate in TAPPI realize how much there is to gain from the networking, educational resources, career development, and other opportunities that come with this involvement. One important opportunity is the ability to share your work and expertise with others in your field, and an excellent way to do this is by taking part in the TAPPI Journal peer-review process, either as an author or a reviewer or both.