A Reflux Classifier consists of a set of parallel inclined channels above a conventional fluidized bed. Recently we (Galvin et al, Chemical Engineering Science, 2009) discovered a new and powerful separation mechanism for elutriating particles on the basis of density, utilizing closely spaced channels. This arrangement suppresses the effects of particle size, thus promoting the effect of particle density. Interestingly, as the channel spacing increases, we observe a transition from laminar flow to particle-induced turbulent re-suspension, with the separations in the wider channels governed according to our previous model described by Laskovski et al (2006). A series of particle fractionation experiments was conducted in this study to examine the effects of the channel spacing, and the transition from laminar to turbuelent re-suspension. Inclined channel spacings of 4, 7, 9, and 18 mm were used in the work. A continuous distribution of coal and mineral matter, consisting of particles in the size range from 0.25 to 2.0 mm was used, with the particle density ranging from 1275 to 2600 kg/m³. The results demonstrate the benefits of the new separation mechanism, with greatly improved fractionation achieved using the more closely spaced channels.
CHEMECA 2009 Conference. CHEMECA 2009: Engineering Our Future: Are We Up to the Challenge?: CD with Proceedings (Perth, W.A. 27-30 September, 2009)