Simulation of Magnetic Field and Flow Field in an External Magnetic Drum Separator Using COMSOL Multiphysics
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摘要:
传统外磁筒式磁选机存在的离心捕收和颗粒分散之间的矛盾，导致低转速下细粒精矿流失严重，而提高转速，预选抛尾率和精矿品位均降低。为综合利用磁性矿物与脉石矿物密度和比磁化系数差异强化目的矿物的捕获，开发了一种新型外磁筒式磁选机，在筒面增加一个向心的冲洗水，以实现矿物颗粒捕收与分散的动态调控。采用COMSOL Multiphysics优化了磁系的磁感应强度、磁场梯度参数；探究了分选筒转速、进水量和筒体倾角对流场的影响，优化了流场特性。仿真结果表明：磁极的表面磁感应强度为1.8 T；磁系的磁力线集中于导磁介质处。同时，在导磁介质表面具有较大的磁场梯度（8×10−7 A/m2）且削减较少，利于磁性颗粒的捕收。本设备优势在于增加向心冲洗水，通过水速变化调节颗粒受力情况，可为永磁磁选机的优化设计提供理论依据。
Abstract:The paradox between centrifugal capture and particle dispersion in traditional external magnetic cylinder magnetic separators led to significant losses of fine−grained concentrate at low rotational speeds, with elevated speeds diminishing both pre−selection tailing rates and concentrate grades. In response, a novel form of external magnetic cylinder magnetic separator was developed to exploit variations in density and specific magnetization coefficients between magnetic and chalcopyrite minerals, enhancing the capture of targeted minerals. Through the implementation of a centrifugal flushing water system on the cylinder's surface, a dynamic control mechanism for capturing and dispersing mineral particles has been successfully realized. COMSOL Multiphysics was used to optimize the magnetic induction intensity, magnetic field gradient parameters and the flow field characteristics of the magnetic system. The effects of sorting cylinder speed, water inlet dynamics, and cylinder inclination on the flow field were investigated. The simulation results indicated that the surface magnetic induction intensity of the magnetic pole was 1.8 T, and the magnetic field lines of the magnetic system were concentrated around the magnetic medium. Moreover, there was a substantial magnetic field gradient (8×10−7 A/m²) on the surface of the magnetic medium, with minimal reduction, which facilitated the capture of magnetic particles. An advantage of this device was the inclusion of centrifugal flushing water. Adjusting the particle forces through changes in water velocity could provide a theoretical basis for the optimization design of permanent magnet magnetic separators.
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表 1 变频器频率与水流量对应关系
Table 1. Correspondence between inverter frequency and water flow
变频器频率 /Hz 0 5 10 15 20 25 水流量 /(m3·h−1) 0 0.4 0.8 1.2 1.6 2.0 
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表 2 N50钕铁硼材料主要性能参数
Table 2. Main performance parameters of N50 NdFeB material
最大磁能
积/(kJ·m−3)矫顽力
/(kA·m−1)内禀矫顽力
/(kA·m−1)剩磁/T 最高工作
温度/℃382～398 828～907 ≥876 1.41～1.45 ≤70
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