中文摘要：

为了寻找能够对重介质旋流器分选密度进行在线调控的方法，以适应原煤煤质的变化，研究了外加磁场对旋流器溢流管直径变径效果的可行性。采用四磁极、极性交替排列（N—S—N—S）布置于非导磁圆管的圆周方向，利用有限元分析软件ANSYS对管内磁场进行模拟，并将以磁铁矿粉为介质配置的一定密度的矿浆泵入四磁极磁场作用的非导磁管进行变径试验。由模拟结果可知，在管内圆周方向磁力分布较均匀，径向有较强的磁场梯度，磁性颗粒能均匀地吸附于管壁上。由试验结果可知，采用外加四磁极永磁体磁场，可以实现溢流管变径，达到重介质旋流器分选密度在线调控的目的。

英文摘要：

In order to find a method of online controlling the separation density of the dense medium cyclone so as to adapt to the property variation of raw coal, a feasibility study on changing the diameter of overflow pipe through external magnetic field was conducted. Four magnetic poles were arranged in circumference of non-magnetic pipe in alternate order （N-S-N-S）, and ANSYS was applied to simulation the magnetic field in the pipe. In addition, the slurry prepared with magnetite powder was pumped into the non-magnetic pipe under the action of the four magnetic poles, so as to conduct the diameter varying test. The simulation results showed： the magnetic force lines distributed evenly in circumference and the magnetic field gradient was large in radial direction inside the pipe, and magnetic particles were evenly absorbed onto the pipe wall. The test results indicated the diameter of the overflow pipe varied with application of four external magnetic poles, thus online control of the separation density of the dense medium cyclone was realized.