Investigation of the magnetic separation performance of a low-intensity magnetic separator embedded with auxiliary permanent magnets

Low-intensity magnetic separators (LIMSs) comprise one of the most widely employed magnetic separation equipment. It is worth studying how to reduce magnetic flux leakage and significantly improve magnetic induction. Typically, auxiliary permanent magnets (APMs) are embedded in the main permanent magnets (MPMs) to increase the magnetic induction. In this study, the effect of the matching relationship between the widths of the MPM and APM and the height of the APM on the magnetic field distribution and magnetic separation performance are investigated. The wider the width of the MPM is, the wider the area of the relatively high magnetic induction intensity. Therefore, increasing the width of the MPM can effectively capture farther magnetic particles, which can effectively improve the magnetic separation performance. In addition, when the size of the MPM is constant, although the height of the APM is increased, the magnetic induction is improved less significantly. The research findings indicate that the height of the APM is approximately two-thirds of that of the MPM, so a satisfactory magnetic field distribution and magnetic separation performance can be obtained. Furthermore, to verify whether APM-LIMSs have advantages, a conventional low-intensity magnetic separator (CON-LIMS) without MPMs was designed. The magnetic field distribution and the effect of important parameters (remnant flux density, drum/tank distance, feeding speed and particle size) on the separation recovery are systematically compared and investigated through detailed computational simulations corresponding to the operating conditions. All the comparison results indicate that embedding APMs in the gaps of MPMs significantly expands the area of relatively high magnetic induction, which can ensure that there is still a strong magnetic force in the area far from the surface of the drum, thereby significantly improving the separation performance. Therefore, APM-LIMSs can capture a wider range and finer particle size. Moreover, APM-LIMSs can select lowcost, ferrite, permanent magnets and set a higher feeding speed and a wider drum/tank distance, thereby significantly increasing the processing capacity while ensuring a high separation performance.