The increasing demand for metals and mineral products, coupled with the critical depletion of known deposits of high grade ore, has led to the development and mining of low grade ore deposits. Before these low grade ores can be of value in a manufacturing or refining process it is necessary that their mineral or metal content be increased by some method of beneficiation. This need for the concentration of low grade ores has led to the development of new processes such as flotation and heavy-media separation and to the improvement of other processes such as magnetic separation.