Modeling and validation of percolation segregation of fines from coarse mixtures during shear motion

Segregation negatively impacts the product quality and depends on physical and mechanical properties of particulate materials. Size is the most dominant parameter contributing towards fines percolation segregation from mixtures with size distribution. A continuum theory-based convective and diffusive model was developed and validated to study time-dependent percolation segregation of fines. In addition, to scale-up the results, a mechanistic theory-based dimensional analysis approach was used to incorporate physical and mechanical properties of particulates in a time-independent model. In dimensional analysis model, size, shape, density, size ratio, mixing ratio, strain rate, strain, and bed depth were included. The results showed that the time-dependent convective and diffusive model predicted the segregated mass of fines within the 95% confidence interval of measured fines for size ratios 2.4:1.0 and 1.7:1.0 at strains of 6% and 10%. Dimensional analysis results showed that the Coefficient of Variation (CoV) of the modeled values with respect to the experimental values were 18%, 15%, and 11%, respectively, for binary mixtures of urea and potash at strains of 2%, 6%, and 10% and strain rate of 0.25 Hz.