A review of HGMS methods of coal cleaning

High Gradient Magnetic Separation has been applied to the problem of cleaning coal in several ways. One is by direct mineral removal from coal slurried in water or oil. Similarly, attempts have been made to desulfurize dry coal. Coal liquids, or solvent refined coal, can have their sulfur and ash content reduced by the filtration or separation of undissolved well liberated minerals. The results of such efforts depend on the magnetic properties of the coal minerals. These have been studied and even altered to improve magnetic separation performance. HGMS has also been employed for indirect use in coal cleaning to recover heavy medium (magnetite) used in fine coal cleaning circuits. This paper is a review of our work on these applications and that of others over several years.