Effect of Magnetized and Demagnetized Feed on Cyclone Performance

Abstract

The hydrocyclone is the primary device used to close the grinding circuits in the taconite industry. The cyclone's major advantages are high capacity, low maintenance, and relatively small size. The main drawback to the cyclone is the fact that it makes a split based on specific gravity as well as size. This has the effect of returning liberated or nearly liberated magnetite back to the ball mills for overgrinding. It is well known that fine magnetite particles will flocculate in the presence of a magnetic field and that these floes settle as pseudo large particles. Therefore, it is reasonable to assume that fine magnetite in cyclone feed would also behave as pseudo large particles and report to the underflow. A number of the early taconite plants included demagnetizing coil on the cyclone feed line. However, plant data on the effect of the demagnetizing of cyclone feed is not readily available, and since there is not a general agreement among plants as to the benefits of demagnetizing the cyclone feed, this project was undertaken to determine the effect of magnetizing and demagnetizing cyclone feed.