A froth separating device was tested in which heavy, hydrophobic particles break froth films and sink to the bottom, while light, hydrophilic particles are supported by the froth to form a top tailings product. Two potential industrial applications for the reverse froth flotation process were evaluated. As a coarse particle flotation technique for sulphide bearing ores, it was found that xanthate pre-conditioning of the ore results in concentrating the sulphur bearing particles to the concentrate. By increasing the xanthate addition, the relative mass recovery as well as sulphur recovery increases. This increase in mass and sulphur recovery is not linear. These results were promising in terms of finding a coarse particle flotation technique for the pre-concentration of sulphide bearing minerals. Preliminary tests indicated that the reverse froth flotation process is not suitable for the replacement of grease belts for fine (-3 mm) diamond recovery. The major concern is the high potential losses of valuable material to the tailings. These losses are mainly due to the fact that the major separation process in the reverse froth flotation cell is based on particle mass beyond a certain critical value. The surface properties of the particle account only for a secondary separation process. Nevertheless, this technique still offers the potential to be applied to coarse coal flotation and recycling waste separation within certain operating limits. (C) 2002 Elsevier Science Ltd. All rights reserved.