Segregation dynamics of complex mixed granules when subject to simple-harmonic vibration

The segregation of granules under vibration is the premise of minerals screening, and particle shape and size are important factors affecting the segregation rate and results. Based on the Discrete Element Method simulation, the dynamics of a single (non-)spherical large particle segregation in the sea of small particles were investigated, the influence of particle shape on its segregation rate was studied. The interaction effect between the shape and the size in a binary uniform mixed particle bed was analyzed, and the distributions of segregation rates as well as the orientations in a multi-component particle group were revealed. The results show that under a strong vibration, the segregation rate of spherical large particles showed a non-monotonic trend of first increasing and then decreasing with the increase of particle size ratio. And the segregation rate of non-spherical large particles is significantly higher than that of spherical large particles, mainly because the particle's bottom end extends to a deeper bed where large porosity fluctuation occurs. In addition, the segregation rate difference between non-spherical large particles and spherical large particles also shows a trend of first increasing and then decreasing with the increase of amplitude. When there is convection in the binary mixed particle group, the segregation rate is significantly higher than that of the non-convective particle group. The segregation rates and rotation orientations of non-spherical particles in the binary bed show a “Gaussian-like” distribution, and there is a competition effect between shape and size, which leads to the abnormal “Reverse-Brazil nut” phenomenon when a small size ratio and low sphericity are given. In addition, the influence of particle shape on the segregation rate is significantly higher than that of particle size structure. Adding intermediate-size particles slows down the segregation process while widening the size distribution range also reduces the segregation rate.