Appl. Sci. 2025 , 15 , 9036
2of 13
quality and energy efficiency presents a key challenge in optimizing the refining process for recycled fibers. Further research has shown that CEL variations also influence fiber morphology, including swelling and flexibility, both of which are critical for achieving desirable paper properties [1,5]. Advanced microscopy techniques and fiber quality analyses have revealed how different CELs can alter fiber structure, thus affecting the performance of the final product. However, most existing studies focus on general fiber types, with limited attention to the unique characteristics and challenges presented by OCCs. OCCs pose specific challenges in the recycling process due to its heterogeneous com- position and the presence of contaminants such as adhesives and coatings—commonly known as ‘stickies’—which can cause operational issues and product defects [4,12]. Ad- ditionally, OCC fibers are typically shorter and more degraded due to multiple recycling cycles, particularly in countries with intensive recycling practices such as South Korea, Japan, Germany, and the Netherlands [1,13]. This deterioration results in lower fiber quality and reduced bonding potential, making effective refining even more critical for OCC-based products [14]. Optimizing refining conditions, especially the CEL of refining plates, is essential for overcoming these challenges. Proper refining can enhance fiber flexibility and surface area, thereby improving bonding strength and the overall quality of recycled paper [5,7,15,16]. By tailoring refining strategies to the specific needs of OCCs, it is possible to mitigate the negative effects of contaminants and fiber deterioration, leading to more efficient and sustainable recycling operations. While previous studies have primarily examined refining plates with relatively short CELs of 14 and 37 km/rev for American OCCs [7], our study uniquely focuses on the effects of a significantly higher CEL of 97 km/s. This much greater CEL represents an ultra-fine bar plate design, which provides a distinct refining intensity and fiber interaction mechanism compared to those investigated previously. By exploring this higher CEL, our research aims to uncover its potential for enhanced refining efficiency, improved fiber length retention, and superior paper property optimization, specifically within the context of Korean OCCs, which presents different recycling challenges and fiber characteristics than American OCCs. This novel focuses on high CEL refining plates, filling an important gap in the literature [7] and providing new empirical data critical for advancing refining technology in recycled fiber processing. This study aims to address the current knowledge gap by systematically investigating the effects of two distinct CELs—37 km/s and 97 km/s—on the refining efficiency of OCCs. Through a series of controlled pilot-scale refining experiments, the research will compare the impact of CEL variation on key metrics such as fiber morphology, tensile strength, and energy consumption. The findings are expected to provide valuable insights into optimizing refining configurations for OCCs, thereby supporting improved sustainability and cost-effectiveness in recycled paper production. Ultimately, this research seeks to inform industry practices by offering empirical data on CEL effects in OCC refining, guiding manufacturers in selecting optimal refining parameters to meet specific product requirements. As the demand for recycled paper continues to rise, a deeper understanding of refining processes and their optimization is vital for advancing the environmental and economic sustainability of the paper industry.
2. Materials and Methods 2.1. Raw Materials
For refining Korean Old Corrugated Containers (KOCCs), domestically manufactured corrugated boxes were collected and used. Their chemical and physical components are summarized in Table 1.
Made with FlippingBook flipbook maker