Continuous separation of bidisperse suspensions in inclined channels

An experimental study was conducted to evaluate the enhancement for the continuous separation of light and heavy particles in an inclined column. A bidisperse suspension consisting of polystyrene (light) and polymethyl methacrylate (heavy) beads of respective uniform size and density, suspended in a salt solution, was used. The total solids volume fraction did not exceed 0.18 to insure uniform lateral concentration profile. The effects of feed flow rate, feed total solids concentration, feed composition, angle of inclination and split ratio on the recovery and on the purity of both species in the overflow and underflow streams were examined. The split ratio is defined as the ratio of the underflow volumetric flow rate to that of the feed. At a fixed feed flow rate, there is a threshold split ratio, beyond which the recovery drops linearly with increasing the split ratio. The threshold split ratio was found to be a function of the operating conditions. At a fixed set of operating conditions, increasing the angle of inclination results in a greater degree of separation. At a given split ratio, there is an optimum feed flow rate beyond which the enhancement decreases as the feed flow rate increases. A mathematical model based on the continuity equations and the PNK concept has been developed that predicts adequately the experimental measurements.