Water based fractionation of particles

A feed of particles covering a wide range of particle sizes and densities was placed into a novel separator, referred to as the Reflux Classifier, and fractionated at a series of fluidization velocities. Double fractionation was then achieved when each product was sieved into narrow size fractions. For the coal particles used in this study, the ash % was determined for each of the samples. The ash % correlated strongly with particle density, and hence was a useful proxy for the particle density. A new Fractionation Algorithm was developed, which provided a method for estimating the feed size and density distribution from the Double Fractionation data. The cumulative yield % versus the cumulative ash % curves for each size fraction, and for the overall feed were then determined. The findings from the study were validated against accurate results obtained using the sink-float method. Excellent agreement with the curves obtained using the sink-float method was obtained. The sink-float method requires the use of heavy liquids; these are invariably toxic and expensive, hence a viable alternative is needed. The water based fractionation method, in conjunction with the Fractionation Algorithm, may prove to be a suitable substitute for the sink-float method. Precise details of the method and algorithm are therefore provided in order to permit the adoption of this new approach by other laboratories.