The influence of magnetic field frequency on eddy current separation

Solid waste contains a large amount of non-ferrous metal resources. Eddy current separation can separate and enrich them. Increasing the eddy current force of is the key to improving efficient separation. The alternating magnetic field frequency plays an important role in regulating the eddy current force. It includes the magnetic roller speed and pole pair configuration. In this study, based on electromagnetic field theory and COMSOL Multiphysics simulation, the influences of the magnetic roller speed and pole pair configuration on the eddy current force of particles with different radii are investigated. And eddy current mechanism and magnetic field mechanism are revealed to explain the relationship between the magnetic roller speed, the pole pair configuration and eddy current force, respectively. Study shows that the optimal magnetic roller speed decreases as the particle size increases and the optimal pole pair configuration is 6 pairs for separating particles with the radii of 2 ~ 16 mm. The results are beneficial for the magnetic roller design and production cost reduction, which will be used to separate larger size range materials. And they also can guide the setting of optimal operating parameters according to the particle sizes.

固体废物中蕴含大量有色金属资源。涡流分选（eddy current separation）技术可对其进行分离与富集。提升涡流力（eddy current force）是提高分选效率的关键。交变磁场频率在涡流力的调控中起着重要作用，其相关参数包括磁辊转速与极对数配置。本研究基于电磁场理论与COMSOL Multiphysics仿真，探究了磁辊转速与极对数配置对不同半径颗粒涡流力的影响，并分别揭示了涡流机制（eddy current mechanism）与磁场机制（magnetic field mechanism），以阐释磁辊转速、极对数配置与涡流力之间的关系。研究表明，最优磁辊转速随颗粒尺寸增大而降低；对于半径为2~16 mm的颗粒，最优极对数配置为6对。该结果有助于磁辊设计优化与生产成本降低，可应用于更大尺寸范围物料的分选，同时还能根据颗粒尺寸指导最优操作参数的设定。