Particle capture of special cross-section matrices in axial high gradient magnetic separation: A 3D simulation

Enhancing the recovery of ultrafine magnetic particles in high gradient magnetic separation (HGMS) is a tough issue in industrial practice. Mathematic modeling has been adopted to describe particle capture in HGMS and many analytical models for regular shape (only circular and elliptic) matrices under ideal conditions (ideal potential flow) have been derived. Irregular shape matrices have better magnetic characteristics and can enhance particle recovery in HGMS. However, analytical models cannot be derived for irregular shape matrices and generally qualitative analyses were conducted, which can hardly be rigorous and convincing. It is essential to develop methods to conduct quantitative analyses for irregular shape matrices. In this paper, 3D numerical simulation was adopted to study particle capture by irregular matrices in axial HGMS. A simulation model consisting of a particle group and magnetic matrices (circular, elliptic, square and diamond cross-section) for axial HGMS was established. Evolution of particle group in the HGMS system employing the four kinds of matrices were detailly demonstrated. Particle motion trajectories were depicted and particle capture cross section area were calculated and compared quantitatively. Elliptic and diamond matrices present better particle capture performance than circular and square matrices under moderate induction range and can be applied to enhance recovery of ultrafine particles. The numerical simulation results are consistent with our previous theoretical studies using analytical models and experimental results on the matrices. The present study also indicates that there should exist optimal aspect ratio for diamond matrices and optimal tooth angle for grooved plates used in HGMS.