Dynamic segregation behavior and its impact on dry beneficiation of fine coal in a gas-solid fluidized bed

Jun Oshitani, Kazuhiro Teramoto, Mikio Yoshida, George V. Franks

This study investigates the dynamic segregation behavior of fine raw coal in a gas-solid fluidized bed and its impact on dry beneficiation performance. While stratification by density and size is well known in fluidized systems, little attention has been paid to the temporal instability of segregation boundaries and how it affects product quality in practical separation processes. Building on previous work that identified an optimal fluidization velocity (u0/umf = 2.0) for separation efficiency, this study focuses on how the bed structure evolves over varying fluidization durations. Bulk density, particle size distribution, calorific value, and ash content were measured across ten vertical layers. The results revealed dynamic fluctuations at the boundary between coal-rich and ash-rich zones, resulting in oscillatory trends in both calorific value and ash content of the product. Notably, ash reduction was more sensitive to these segregation dynamics than combustible yield, indicating that impurity rejection can be fine-tuned by optimizing fluidization time. These findings underscore the importance of controlling temporal segregation behavior to enhance the stability and efficiency of dry coal beneficiation systems.

International Journal of Coal Preparation and Utilization

10.1080/19392699.2025.2589979