To produce an on-line control method to improve the separation density of a given suspension density of a dense medium cyclone, a thin solenoid coil was placed in the cylindrical part of a cyclone. The dense medium distribution test and -3 + 0.125-mm coarse slime separation tests for different electric currents were performed. Float-and-sink analysis was performed for the separation products. The magnetic force of the particles under a magnetic field was also simulated. The results indicated that the presence of a magnetic field can improve the separation density by increasing the "separation cone density" caused by the inward radial motion and the upward axial motion of the magnetic particles. This approach provided a new separation density manipulation method for dense medium cyclones via application of a magnetic field. (C) 2014 Elsevier Ltd. All rights reserved.