Influence of Impeller and Mixing Tank Shapes on the Solid–Liquid Mixing Characteristics of Vanadium-Bearing Shale Based on the DEM-VOF Method

Abstract

The mixing tank is important equipment for industrial applications in the wet vanadium extraction process, but in practice, there are problems, such as uneven mixing of minerals. In this study, the effect of different types of impellers and different mixing tank structures on the suspended mass of particles was simulated using the discrete element method and volume of fluid method (DEM-VOF). The simulation results show that the round-bottomed tank performed mixing better than the flat-bottomed tank at different particle densities, and the flat-bottomed tank was prone to particle stratification and other phenomena. The round-bottomed mixing tank could better improve the solid–liquid suspension effect. In this study, the coefficient of variation σ was introduced to characterize the suspended mass of particles. By monitoring the σ value, it was found that the blade pitch angle 45 (BPA45) had the best mixing uniformity in the inclined pitched blade turbine (PBT). As the PBT impeller pitch angle increased, the particle suspension increased. When comparing different types of impellers, the Rushton exhibited a 45% improvement in mixing uniformity relative to the BPA45. Second, the width and height of the trough bottom projection were optimized and their σ values were calculated separately for different parameter conditions. The width of 0.05 m and height T/4 (T being the diameter of the tank) were finally determined to be the optimum parameters for the optimal design of the vanadium shale leaching mixing trough.