Application of inclined channels in the hydrodynamic classification of minerals by particle size – Extension to coarser separations

A REFLUX™ Classifier was used to classify a silica feed (0–710 µm) based on particle size. Split Fluidisation was used to generate remarkably sharp separations involving solids throughputs of up to 92 t/m²/h. This work builds on the previous study by Starrett and Galvin (2023) but with a focus on coarser separations at higher throughputs. As the separation size increased, there was increasing misplacement of fine particles in excess of 75 µm into the coarse underflow stream. This problem was averted by halving the cross-sectional area of the lower section of the REFLUX™ Classifier. This change led to a doubling of the superficial fluid velocity in the lower section for a given set of flow rates, ensuring fine particles were unable to settle into the coarse underflow. In general, the separations performed in this study show complete closure of the partition curve at both the coarse and fine ends. It was also found that to deliver sharp separations it is essential to introduce sufficient water to the separator, per unit of solids transport to the overflow, especially for higher solids throughputs with coarser separations. Although the fluidisation rate can be used to control the separation size at finer separations (below 180 µm) and lower throughputs, ultimately the bias flux provides the basis for controlling the separation size at coarser sizes and higher throughputs.