Parametric investigations of different variables on liquid–solid fluidization in a HydroFloat cell using computational fluid dynamics

Abstract

In flotation, the fluidization can enhance the coarse particle recovery which is dependent on the quiescent flow condition and is also affected by the liquid–solid interphase drag force. In this study, the liquid and particle flow behaviours are investigated by using the Eulerian-Eulerian two-fluid model combining the kinetic theory of granular flow (KTGF) coupled with the RNG k-ε turbulence model in 3D computational geometry. Syamlal & O’Brien, Gidaspow, Gidaspow+Ganser, and Gidaspow+Haider & Levenspiel drag models are examined. The comparison of predicted results and experimentally obtained data using a HydroFloat (HF) cell showed that the drag models for the irregular particle (Gidaspow+Ganser and Gidaspow+Haider & Levenspiel) have a maximum relative error of 3.05% which is much better than the drag models for the sphere particle (Syamlal & O’Brien and Gidaspow). Also, the effect of restitution coefficient for particle-particle collisions, specularity coefficient for wall-particle collisions and initial solid holdup on the overall bed voidage, axial RMS (root mean square) velocity, granular temperature, and pressure of the solid particle are investigated, while the Gidaspow+Haider & Levenspiel model is used as the drag model. The voidage increases with increasing restitution and specularity coefficients. The particle axial RMS velocity is less significant up to 6.3% of the total HF height and the location of strong circulation is identified. The granular temperature is insignificant for the case of nearly inelastic collision (0.0001) or nearly no-slip condition (0.0001), but superficial liquid velocity affects significantly the granular temperature for both cases. The effect of restitution coefficient and superficial liquid velocity on solid pressure is very significant for the case of the nearly no-slip condition.