Advanced Flotation Washability (AFW) analysis procedure utilizing a novel batch-operated flotation column, has been developed to obtain the ultimate flotation coal cleaning performance. The separation performance obtained from the AFW procedure was superior to those obtained from release and tree analyses, as well as, those obtained from multiple stages of flotation cleaning. Based on this ultimate separation performance, a new characteristic Flotation Index was derived, which provides a quantitative measure of the ash and sulfur cleaning potential of a coal. Utilizing the flotation index concept, a comparative study was conducted to evaluate the separation performances achievable from three leading column flotation technologies. One of the counter-current systems, which provides a near plug-flow flotation environment due to the presence of corrugated packing material in the cell, produced the best separation performance. On the other hand, the carrying capacity achieved by a self air-inducing co-current system, which provides an intimate bubble-particle attachment environment characterized by an extremely high air fraction and ultrafine bubbles, was found to be the maximum.