Gas dispersion properties in fluidized bed flotation columns

The precise resolution of gas dispersion parameters in multiphase flows is crucial for optimizing fluidized bed flotation performance. This study presents the first comprehensive investigation integrating electrical resistance tomography and dual-tip conductivity probes for simultaneous, in situ measurement of gas holdup and bubble size distribution in a fluidized bed flotation column (FBFC). We uniquely combined these advanced techniques to resolve spatial–temporal gas dispersion characteristics under varying operating conditions, involving water velocities, gas velocities, particle sizes, and initial static bed heights. Subsequently, bubble surface area flux was calculated based on the measured Sauter mean diameter. The results indicate a strong dependency on the mean cross-sectional gas holdup on the operating conditions investigated. A novel predictive equation for mean cross-sectional gas holdup is formulated, incorporating several dimensionless numbers, with a mean relative error remaining within ±12.56%. The bubble size distribution exhibited a right-skewed characteristic and adhered to a lognormal distribution, indicating that both bubble Sauter mean diameter and bubble surface area flux can be optimized through adjustments to the experimental parameters. Furthermore, a predictive model for bubble Sauter mean diameter was established using drift flux analysis, which demonstrated a mean relative error of ±15.43% when compared to experimental values within the range of parameters examined. These advancements not only enhance fundamental understanding of multiphase hydrodynamics but also establish a foundation for control strategies in FBFC.