The effect of magnetic field on the performance of a dense medium separator

The application of a vertically oriented magnetic field external to a dense medium cyclone can be used to manipulate the density differential within the cyclone by influencing the cyclone's internal ferrosilicon distribution. Tests were conducted on a well-defined dense medium system using a pilot-plant cyclone equipped with a solenoid magnet. The objective was to determine the yield to the dense medium cyclone underflow of a sample consisting predominantly of quartzite material, as a function of the magnetic field strength of the solenoid magnet, and as a function of solenoid position. It was observed that for a specific selection of magnetic field strength and solenoid position, the concentrate yield was reduced. A decrease in yield to concentrate is advantageous in that it reduces the mass of material to be processed downstream. The yield reduction was found to be a function of the applied magnetic field strength. Furthermore, it was found that a disruption in the ferrosilicon flow pattern inside the cyclone may occur beyond a certain magnetic field strength which leads to impaired cyclone operation.