Accurate calculation of major forces acting on magnetic particles in a high-gradient magnetic field: A 3D finite element analysis

Abstract

Magnetic agglomeration of magnetic particles under the influence of magnetic field plays a vital role in enhancing the separation of fine magnetic mineral particles. In this study, the major forces acting on weakly magnetic particles and the ratio between forces in high-gradient magnetic separators (HGMS) are investigated. A 3D high-gradient magnetic field based on HGMS was simulated, and the major forces (magnetic force Fm, magnetic agglomeration force Fmm, and gravity G) acting on weakly magnetic particles were calculated in the form of Fm/Fmm, Fm/G by finite element method (FEM). The results show that the value of Fm/Fmm became lower as the increase of magnetic field intensity and the relative permeability of particles, higher as the increase of the magnetic field gradient, the particle size and the distance between particles. However, there was no correlation between the value of Fm/Fmm and the density of the magnetic particles. Furthermore, the value of Fm/G was inversely proportional to the density of the particles and directly proportional to the relative permeability of particles, the magnetic field intensity and magnetic field gradient. Meanwhile, Fm was at least 190 times greater than Fmm in any case and Fm was far bigger than G in most cases, indicating that the magnetic agglomeration is not significant in HGMS and gravity has little effect on high-gradient magnetic separation, and HGMS are destined to be a kind of high-efficiency magnetic separation equipment.