Coal flotation washability: Development of an advanced procedure

A modified coal flotation characterization procedure, referred to as the Advanced Flotation Washability (AFW) technique, has been developed which, compared to traditional procedures, provides a more accurate prediction of the optimum separation performance achievable by a froth flotation process. The AFW procedure uses a batch-operated flotation column packed with corrugated plates which provides enhanced selectivity among particles of varying degrees of hydrophobicity due to a selective bubble-particle detachment mechanism. This mechanism is more pronounced in a flotation column operating under carrying-capacity limited condition with a deep froth zone. In addition, the plug-flow environment resulting from the apparent high length-to-diameter ratio provides an improved performance over the near perfectly-mixed conventional cells used in the traditional procedures. The separation performance provided by the AFW procedure was superior to that obtained from multiple stage cleaning provided by commercially-available flotation columns under both kinetic and carrying-capacity limiting conditions. The separation performance improvement provided by the AFW technique has been illustrated using three different coal samples having varying feed characteristics.