Search

Editorial: Special issues in March and May TAPPI Journal focus on the latest pulp manufacture and engineering research, TAPPI Journal March 2024

ABSTRACT: This issue, organized by Editor-in-Chief Peter Hart, features content from the 2023 PEERS/IBBC Conference that has been peer reviewed for publication in TAPPI Journal. The papers encompass a range of topics:œ Two papers, from researchers Suarez et al. at WestRock, examine pulp from nonwoods like wheat straw and sugar-cane bagasse using a holistic life cycle analysis approach to project environmental performance in packaging products. The results can help mills make decisions about which fibers ensure a low carbon footprint.

Life cycle carbon analysis of packaging products containing nonwood residues: A case study on linerboard and corrugating medium, TAPPI Journal March 2024

ABSTRACT: Circularity is creating momentum toward utilizing waste feedstock in a myriad of applications. The paper industry is not an exception to this trend, and packaging products made from agricultural or agro-industrial residues are receiving more attention now than ever. Additionally, negative consumer perceptions of tree felling are accelerating the acceptance of these fibers. Nevertheless, adopting these residues raises the issue of whether they constitute a better alternative to fight climate change than wood. Answering this question is imperative to ensure that pledges to reduce carbon footprints across the industry are fulfilled. This paper aims to estimate the carbon footprint of corrugating medium and linerboard containing wheat straw and sugarcane bagasse pulp compared to analogous wood-based materials. The goal was also to understand how methodological decisions to allocate emissions to nonwood residues can affect the results. This study includes a life cycle carbon analysis spanning from cradle to grave, which comprises stages for residue production, pulping, paper-making, waste management, and corresponding transportation. For the proposed case study, the results suggest that straw- and bagasse-based medium and linerboard can present a higher carbon footprint than products made from virgin and recycled wood fibers. The main driver is the production of nonwood chemimechanical pulp. In addition, the lower capacity of nonwood residues to be recycled increases the overall impact. Finally, decisions around emissions allocation highly influence the results. This study helps mitigate part of the uncertainty around the environmental sustainability of corrugating medium and linerboard made from the selected nonwood residues.

Life cycle carbon analysis of packaging products containing purposely grown nonwood fibers: A case study on the use of switchgrass pulp for linerboard and corrugating medium, TAPPI Journal March 2024

ABSTRACT: Sustainability is driving innovation in the pulp and paper industry to produce goods with lower carbon footprints. Although most of the efforts are currently focused on increasing energy efficiency or switching to renewable fuels, the attention toward alternative feedstocks has increased in recent years. Claims of nonwood fibers requiring lower use of chemicals and energy than wood fibers, along with negative consumer perceptions of tree felling, are helping purposely grown nonwoods to gain market share. The potential nonwood fiber environmental superiority over virgin or recycled wood fibers remains controversial and is often driven more by emotion and public perception rather than facts. This paper estimates the carbon footprint of corrugating medium and linerboard containing switchgrass pulp compared to analogous wood-based materials. The study includes a life cycle carbon analysis spanning from cradle to gate, which comprises stages for fiber production, pulping, papermaking, and corresponding transportation. Carbon footprints for virgin linerboard, recycled linerboard, virgin medium, and recycled medium were estimated at around 510, 620, 460, and 670 kg carbon dioxide equivalent per metric ton (kg CO2eq/t), respectively. Replacing 30% of the virgin or recycled material with switchgrass pulp translated into carbon footprint increases of around 60%, 45%, 62%, and 38%, respectively. Thus, for the proposed case study, the results suggest that switchgrass-based medium and linerboard can present a higher carbon footprint than products made from virgin and recycled wood fibers. The main driver is the production of nonwood mechanical pulp.This study was designed to mitigate part of the uncertainty around the environmental sustainability of medium and linerboard made from the selected purposely grown nonwood fibers.

Effects of varying total titratable alkali and causticizing efficiency targets on kraft pulp mill productivity, TAPPI Journal March 2024

ABSTRACT: The kraft mill causticizing area is often overlooked and undervalued when it comes to mill optimization; however, the operation of the causticizing plant has downstream effects on the entire liquor cycle. Setting the right targets for the causticizing plant can have a tremendous effect on mill operating costs, as well as push the production bottleneck from one unit operation to another. The key performance parameters associated with the causticizing plant itself are liquor total titratable alkali (TTA) and causticizing efficiency. Individual facilities choose their TTA and causticizing efficiency targets based on their goals, the limits of their equipment, and past experiences. This gives a variety of operating strategies in practice, but what are the implications for optimizing total titratable alkali and causticizing efficiency, and what level of optimization can be achieved through implementation of modern technology? This paper reviews the results of several different operational strategies and models the effects of these different approaches on kraft mill liquor cycle.

Factors affecting phosphorus uptake/dissolution during slaking and causticizing, TAPPI Journal March 2024

ABSTRACT: Hydroxide is regenerated in the recovery cycle of kraft pulp mills by the addition of lime (CaO) to green liquor. Phosphate in green liquor can react with the lime during slaking/causticizing. Total titratable alkali (TTA), sulfidity, the concentration of phosphate in the green liquor, temperature, and the liming ratio were all variables explored in this work to determine their influence on phosphorus uptake and dissolution. Experiments were also run in which the lime was slaked before being added to the green liquor to separate reactions with phosphate during slaking and reactions that occur during causticizing. Both reburnt lime and technical grade CaO were used. The experiment results indicate that phosphorus primarily reacts with slaked lime (Ca(OH)2), and that the final concentration of phosphate in the white liquor at the end of slaking and causticizing is nearly independent of the initial concentration of phosphorus and only mildly dependent on the carbonate concentration in the green liquor. There do appear to be differences in the rate at which phosphate reacts with reburnt lime and technical grade CaO, though the reason for this was not determined.

TAPPI Journal Summaries, Paper360º March/April 2024

Utilization of Areca leaf residues for sustainable production of greyboard, TAPPI Journal May 2024

ABSTRACT: This study primarily focused on the production of greyboard using waste materials from small scale industries, and specifically using Areca leaf waste fibers as a sustainable and environmentally friendly resource. Areca leaf waste fibers were employed as the primary raw material for greyboard manufacturing. The resulting greyboard exhibited commendable properties, including a tear index of 7.53 mN·m2/g, tensile index of 18.34·N·m/g (i.e., breaking length of 1870 m), burst factor of 9.24 (gf/cm2)/(g/m2) and stiffness factor of 33.1. This greyboard was created through a series of steps, including hydrothermal treatment of the material at 155°C and mechanical pulping refinement. The produced greyboard met the specifications outlined in the Indian Standard 2617 (1967) for greyboard. The key objective of this work was to leverage agricultural waste resources to develop a chemical-free greyboard, resulting in reduced waste disposal in open fields and a decrease in chemical usage within the greyboard manufacturing industry. Various characterization techniques, including field emission scanning electron microscopy (FE-SEM), attenuated total reflection•Fourier transform infrared (ATR-FTIR) analysis, and X-ray diffraction (XRD), were used to assess the fiber quality, including aspects such as functional groups, morphology, and crystallinity for the materials used in the manufacturing process.

Unlocking Profit Potential: How US Pulp Mills Can Capitalize on Carbon Capture, Paper360º May/June 2024

Continuous digester process safety improvements • Stress corrosion cracking and overpressure protection lessons learned and opportunities, TAPPI Journal October 2024

ABSTRACT: Georgia-Pacific has recent experience with continuous digester stress corrosion cracking (SCC) repairs where the extent of SCC was more than previous spot inspections had predicted (one digester had anodic protection, one did not). This paper offers case studies of reviewed and improved digester inspections by use of “boat” samples to quantify the depth of cracking mechanism. Boat sample test data is used to support repair recommendations based on hardness testing. Georgia-Pacific also reviewed overpressure protection systems and corrected gaps found in these systems. These included updating to the latest original equipment manufacturer (OEM) designs and formalizing functional testing procedures and practices. This review of digester inspection, testing, and repairs since 2020 provides: (1) a basis for including a 3rd party corrosion expert to be a part of inspections; (2) removes the use of power-wire brushes; (3) enhances digester inspection with 100% phased-array ultrasonic testing to detect SCC; and (4) ensures overpressure protection design and testing is aligned with corporate needs and the site-specific challenges.

Application of ATR-IR measurements to predict the deinking efficiency of UV-cured inks, TAPPI Journal January 2022

ABSTRACT: In recent years, ultraviolet (UV)-curable ink has been developed and widely used in various printing applications. However, using UV-printed products (UV prints) in recovered paper recycling causes end-product dirt specks and quality issues. A new method was developed that can distinguish UV prints from other prints by means of attenuated total reflectance infrared (ATR-IR) spectroscopy. Application of this method could allow more efficient use of UV prints as raw materials for paper recycling.First, a mill trial was performed using UV prints alone as raw materials in a deinked pulp (DIP) process. Second, test prints were made with four types of UV inks: a conventional UV ink and three different highly-sensitive UV inks. Each print sample had four levels of four-color ink coverage patterns (100%, 75%, 50%, and 25%). Next, deinkability of all prints was evaluated by laboratory experiments. Finally, each print was measured using the ATR-IR method, and the relationship between the IR spectra and deinkability was investigated. Mill trial results showed that UV prints caused more than 20 times as many dirt specks as those printed with conventional oil-based ink. There were variations in recycling performance among UV prints taken from bales used for the mill trial. Lab tests clearly revealed that not all UV-printed products lead to dirt specks. In order to clarify the factors that affected deinkability of UV prints, the print samples were investigated by lab experiments. Key findings from lab experiments include: œ The number of dirt specks larger than 250 µm in diameter increased as the ink coverage increased. œ Higher ink coverage area showed stronger intensity of ATR-IR spectral bands associated with inks. These results indicate that deinkability of UV prints could be predicted by analysis of ATR-IR spectra. œ Finally, the method was applied for assessment of recovered paper from commercial printing presses. It was confirmed that this method made it possible to distinguish easily deinkable UV prints from other UV prints. Based on these findings, we concluded that the ATR-IR method is applicable for inspection of incoming recovered paper.