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Magazine articles
Water chemistry challenges in pulping and papermaking • fundamentals and practical insights: Part 1: Water chemistry fundamentals and pH, TAPPI Journal June 2022
ABSTRACT: Water is an essential component of the papermaking process. Nevertheless, papermakers often overlook its importance compared to fibers and chemical additives. A better understanding of water properties and chemical interactions associated with water at the wet end leads to a sound foundation for high-quality paper production and smooth operation. Not all fresh water and process water is the same. Fresh water varies from mill to mill, primarily due to the location and availability of water sources. Some industrial trends, such as enhancing water conservation and production yield, gradually shift process water quality over time. The current work serves as a primer on water and water chemistry fundamentals to help the papermaker prepare for the future challenges of increased contamination of process water associated with reduced fresh water usage. This paper focuses on basic water chemistry definitions and discusses the impact of pH on wet-end operation. It is clear that pH is a fundamental factor that directly affects the process and impacts other factors relevant to the papermaking process. It is crucial to understand what pH represents, how it is measured, how to select the proper pH and carefully control it, and how to closely maintain the process at target setpoints. Understanding the sensitivity of operation to pH change will lead to an appropriate focus on these issues. In addition to basic theory, we also review onsite experience and practical mill cases. It is imperative to stress that, although critical, pH is not the only chemical parameter impacting papermaking operations. Other factors, such as ionic concentration measured by conductivity, surface, soluble charge, and hardness, are critical and will be discussed in Part II of this series. As pH is a primary and independent factor that impacts various forms of charge and conductivity, the authors decided to start the current series of papers by discussing pH.
Conference papers
Accelerated Sludge Digestion at a Kraft Mill Using a Biostim
Accelerated Sludge Digestion at a Kraft Mill Using a Biostimulant, 2015 PEERS Conference
Conference papers
High Power Generation From Recovery Boilers, What Are The Li
High Power Generation From Recovery Boilers, What Are The Limits?, 2015 PEERS Conference
Conference papers
Evaporators, The Place To Look For Energy And Water Usage Re
Evaporators, The Place To Look For Energy And Water Usage Reductions, 2015 PEERS Conference
Journal articles
Magazine articles
Mechanical modification of softwood pulp fibers using a novel lightweight vertical bar plate, TAPPI Journal April 2021
ABSTRACT: Refiner plates made using sand casting have a draft angle, which results in a trapezoidal bar shape. These trapezoidal bar plates have a limited throughput compared to the vertical bar plates, and eventually the edges of the bars become dull, resulting in longer time to reach the target freeness and shorter service life. The new light-weight refiner plate with a bar insertion method into a plate base was developed by selecting an aluminium-based alloy as the plate base material and a stainless steel alloy with high wear resistance as the bar material. The light-weight plate with sharp bar edges was very effective in reducing refining energy by reaching the target freeness faster than the sand-cast bar plate. Finally, the lightweight sharp bar plate, which weighed only about half the weight of the cast bar plate, was expected to significantly contribute to easy replacement, improved paper quality, and larger throughput without excessive loss of fiber length.
Journal articles
Examination of the potential to reduce water application rat
Examination of the potential to reduce water application rates for hardwood pulp logs stored in wet decks, TAPPI JOURNAL August 2016
Journal articles
Alkyl ketene dimer (AKD) sizing of paper under simplified tr
Alkyl ketene dimer (AKD) sizing of paper under simplified treatment conditions, TAPPI JOURNAL August 2016
Journal articles
Magazine articles
A case study review of wood ash land application programs in North America, TAPPI Journal February 2021
ABSTRACT: Several regulatory agencies and universities have published guidelines addressing the use of wood ash as liming material for agricultural land and as a soil amendment and fertilizer. This paper summarizes the experiences collected from several forest products facility-sponsored agricultural application programs across North America. These case studies are characterized in terms of the quality of the wood ash involved in the agricultural application, approval requirements, recommended management practices, agricultural benefits of wood ash, and challenges confronted by ash generators and farmers during storage, handling, and land application of wood ash.Reported benefits associated with land-applying wood ash include increasing the pH of acidic soils, improving soil quality, and increasing crop yields. Farmers apply wood ash on their land because in addition to its liming value, it has been shown to effectively fertilize the soil while maintaining soil pH at a level that is optimal for plant growth. Given the content of calcium, potassium, and magnesium that wood ash supplies to the soil, wood ash also improves soil tilth. Wood ash has also proven to be a cost-effective alternative to agricultural lime, especially in rural areas where access to commercial agricultural lime is limited. Some of the challenges identified in the review of case studies include lengthy application approvals in some jurisdictions; weather-related issues associated with delivery, storage, and application of wood ash; maintaining consistent ash quality; inaccurate assessment of required ash testing; potential increased equipment maintenance; and misconceptions on the part of some farmers and government agencies regarding the effect and efficacy of wood ash on soil quality and crop productivity.
Journal articles
Magazine articles
Key material properties in crease cracking of kraft paper, TAPPI Journal February 2021
ABSTRACT: Crease cracking of paperboard is important to control for the appearance and structural integrity of packages. Crease cracking is affected by creasing operation variables, as well as the physical properties of the paperboard. However, the effects of the physical properties are not clearly known. The objectives of this work were to identify the key material properties that affect crease cracking and to clarify the effects of fiber composition and starch. Laboratory sheets were produced from bleached and refined softwood and hardwood commercial pulp at grammage and thicknesses that match a typical paperboard. To mimic papermaking operations, surface starch was applied via a bench-top size press. The sheets were creased in the lab over a range of penetration depths, and reverse-side cracking was measured. The results showed that less reverse-side cracking was correlated with higher tensile post-peak energy, a lower bending stress, and a lower z-direction (ZD) stiffness. The tensile post-peak energy is a measure of the resistance to crack growth via fiber-bridging. The bending force and the ZD stiffness influence the forces that create cracks. It was observed that decreasing the ratio of hard-wood-to-softwood content and reducing the amount of starch would both decrease crease cracking.
Journal articles
Magazine articles
Application of foamed additives to the surface of wet handsheets, TAPPI Journal January 2021
ABSTRACT: We explored the application of foamed wet-end additives onto wet handsheets to qualify our method of application and to demonstrate the method’s usefulness for prescreening additives and foaming agents for packaging applications.We modified a laboratory drawdown coating machine to allow coating of wet handsheets with foamed additives. Initial sheet solids were adjusted to a target of 8%•25% by vacuum. Foam layer thickness was set mechanically. After application, the foamed additives were drawn into the sheet with vacuum. The additive dosage was adjusted by altering its concentration within the foaming formulation. We evaluated more than 100 foaming agents and 10 strength additives, comparing wet-end and foam-assisted addition with no addition on recycled linerboard and virgin linerboard furnish. Foam-assisted addition typically displayed a much steeper dose-response curve and much higher maximum strength levels than wet-end addition. Our results suggest potential target applications for this technology, such as lightweighting, and improved strength performance in mills with relatively closed water systems, where strength aids added into the wet end are adversely influenced by accumulation of inorganic ions and organic species.