Experiments and CFD-DEM simulations of fine kaolinite particle sedimentation dynamic characteristics in a water environment

Fine kaolinite particles are mineral particles that are found in mine wastewater. The particles' shape is one of the parameters that causes a significant change in the sedimentation dynamics in water environments. In this work, experimental methods and Computational Fluid Dynamics - Discrete Element Method (CFD-DEM) methods served to investigate the dynamic characteristics of fine kaolinite particle sedimentation. The Results of statistical analyses show that the length-width ratio of fine kaolinite particles is 1–3 and the average simplified spherical coefficient is 0.625 in the 50–500 μm particle size range. The simplified spherical coefficient formula proved to be effective according to experimentation and simulations. Moreover, the effects of particle size, liquid viscosity, and liquid velocity on kaolinite particle sedimentation dynamic characteristics were numerically studied in detail by using the modified spherical coefficient. The simulation revealed that an increase in liquid viscosity resulted in a declining particle terminal velocity. However, the sensitivity of the particle terminal velocity affected by liquid viscosity fell when the particle size also declined. When an increase in particle size occurred, the sensitivity of the particle terminal velocity to the influence of upwelling water decreased. • The average l / w and Φ k of fine kaolinites are 1.703 and 0.625, respectively. • The error of Φ k when it is greater than 0.490 can be controlled within 5%. • Several sedimentation dynamic characteristics were investigated using CFD-DEM. • The influence of upwelling water increases when particle size decreases. • Particles' terminal velocity decreases with an increase in liquid viscosity.