Coal preparation or the cleaning of coal involves its selective separation from mineral matter. The latter is composed mainly of clay minerals. Flotation is used to separate fine hydrophobic coal particles from the hydrophilic clay particles. However the separation process can be inefficient if the coal is oxidised, or if the clay is present as composite particles with coal or as slime coatings on the coal surface, which results in decreased overall coal hydrophobicity and flotation. This study has investigated the effect of fine clay on the flotation of several coal samples. It was found that addition of fine clay particles to coal decreased coal flotation recovery and rate. This coal depression was stronger with smectite than with kaolinite addition. The adverse effect of clay on coal flotation was more pronounced for a moderately floating coal that a strongly floating coal. Furthermore, the removal of fine particles (which are mainly clay particles) either from the primary tailings or the feed sample by sieving (38 μm) or desliming with a hydrocyclone gave vastly improved flotation performance of the coarse coal particles. This process recovered coal that did not float in the primary flotation stage, and would otherwise be lost to the process. In both cases, the removal of slimes from the circuit gave a better overall combustible recovery than processing a feed that had no pretreatments employed.