A resurgence in the interest in pre-combustion coal cleaning using dry, density based separators has occurred recently due to advancement in available technology and the rising need for effective, low-cost separations in applications where water availability is limited. Tests performed at various mine sites throughout the U.S. on run-of-mine coals of varying rank has shown that the FGX Separator has the potential to provide an efficient, high density separation of around 2.0RD. In some cases, air-based concentration table produced a product that met contractual specifications by reducing the ash content to values below 10%. For a lignite coal, the FGX unit also achieved total sulfur and mercury reductions of 35% and 54%, respectively, in several tests. The high density separation also allows the potential of significantly reducing the amount of run-of-mine material that is loaded and hauled to a wet-based preparation plant. In the Central Appalachia coalfields in the U.S., run-of-mine coal containing as much as 70% rock is hauled from the mine to the cleaning facility at distances up to 32 km. The separation performances achieved by the FGX unit indicate the ability to reject 70%-90% of the high density material which can be used for reclamation purposes at the mine site. In one application, the FGX reject contained around 0.7% 1.6RD float material which indicates a very low loss in coal when rejecting 36% of the 2.1RD sink material in the feed. This publication will present and discuss the results obtained from the evaluation of the FGX Separator for the cleaning of the +6mm fraction in coals of varying rank.