Application of inclined channels in the hydrodynamic classification of minerals by particle size – Part III – Extension to high volumetric feed fluxes and low concentrations

• Particle size classification was investigated using a REFLUX™ Classifier. • High volumetric feed fluxes allowed for remarkably sharp separations. • At low solid concentrations, the overall water rate becomes a key control variable. • There is a linear correlation between inferred suspension viscosity and Imperfection. This work builds on two previous studies ( Starrett and Galvin, 2023 , Starrett and Galvin, 2025 ) using a REFLUX™ Classifier to separate a silica feed (0–710 µm) based on particle size. Here the focus was on the factors that control the separation size at low solids concentration and high volumetric feed fluxes. Feed suspensions at concentrations of ∼ 2 to 8 wt.% solids and volumetric feed fluxes up to 250 m 3 /(m 2 h) were used. A hydrodynamic floor, referred to as “Split Fluidisation”, ensured virtually no by-pass of fine particles to the coarse underflow stream, whilst the system of inclined channels ensured virtually no coarse particles were entrained via the fine stream to the overflow. The partition curves continued to exhibit full closure, however, were sharper than the separations in the previous studies with Imperfections, I = E p / D 50 , in the range of 0.06–0.07. Across the three studies, a linear relationship was obtained between the inferred suspension viscosity and the Imperfection, providing a new insight into understanding the factors that govern the Imperfection.