The Reflux Classifier was applied to the separation of coal and mineral matter over different size bands, −8 + 0.5 mm, −2 + 0.25 mm, and −2 + 0.075 mm. The technology consists of a fluidized bed, with a system of parallel inclined channels above. Significant improvement in separation efficiency was achieved by exploiting new separation mechanisms that apply to particles of a given size within the inclined channels. For the coarsest size range, the use of a sufficiently large channel aspect ratio, defined by the channel length to gap ratio, leads to separation densities that are independent of the particle size, and in turn strong control of the cut point. For the finer particles, a new and powerful separation mechanism was exploited, leading to a major reduction in the variation of the particle separation density with particle size, and to a significant reduction in the Ep. The new separation mechanism, achieved through the use of appropriate, closely spaced, inclined channels leads to significant suppression of the effects of particle size in the particle size range −2 + 0.075 mm, even at low solids concentration. For example, over the size range 0.25 to 2.0 mm Ep values of 0.06 to 0.08 were obtained.
International Journal of Coal Preparation and Utilization Vol. 30, Issue 2-5, p. 130-144