ABSTRACT
There is a very distinct density difference between coal, with a specific gravity of 1.5, and its most common impurities, almost all specific gravities above 2.6. This difference allows for very efficient gravity separations within the coarser particle fractions. These separations can be made more efficiently by the use of a liquid phase that is denser than the coal. This chapter describes the methodology behind such heavy media separations, including case studies, dense liquid selection, and the basic principles behind the separators. The major difficulties of heavy-media separation are also addressed: the toxicity and expense of true heavy liquids, and the particle size limitations of micronized magnetite slurries.
