Magnetic separation: A review of principles, devices, and applications

Conventional magnetic separation devices are widely used for the removal of tramp iron from a variety of feed materials and for the beneficiation of ferrous ores. These devices for separation of strongly magnetic materials employ a variety of mechanical designs. Recently developed high gradient magnetic separation devices extend the useful application of magnetic separation to very weakly magnetic materials of small particle size. Potential applications of these new devices in pollution control, chemical processing, and the benefication of nonferrous low grade ores is indicated. The principle of operation of magnetic separation devices is the interaction between magnetic forces and competing gravitational, hydrodynamic, and interparticle forces within the magnetic separator. Without resort to a detailed analysis of the separation process, an understanding of the characteristics of magnetic separators is possible by consideration of a simple force-balance model. Descriptions of the conventional grate, drum and belt magnetic separators, laboratory magnetic separators, and several high gradient devices are given to illustrate the devices of major commercial importance and to illustrate the physical principles of magnetic separation.