Development of a mechanistic model of granular flow on vibrating screens

Abstract

Abstract Screening is often applied to separate granulated ore materials into multiple particle size fractions. Therefore, achieving optimal efficiency in the screen performance becomes essential for improved downstream processing. Several techniques such as physical modelling, empirical modelling, mathematical modelling and the discrete element method (DEM) have been adopted by scientists and engineers to study granular flow on vibrating screens. However, advancement in the current state-of-the-art modelling of particle screening requires a mechanistic understanding of their motion along the screen. This necessitates the need to fully quantify the granular rheology determined by the depth of the particle bed along the screen, the solid concentration, and the average velocity of the granular avalanche on the screen. In this study, the concept of granular rheology is applied to study granular media on vibrating screens. This approach overcomes the extreme dependency on machine-specific empirical models for vibrating screens. The kinematic outputs from DEM simulations are used to formulate a visco-plastic model of the granular rheology along an inclined vibratory screen. This mechanistic screening model includes a description of the rheology of granular flow on a vibrating screen. The model captures the flow transition from a quasi-static phase to a dense-flow regime. The quasi-static regime transition occurs at the inertial I value of 0.018, the dense-like regime to a turbulence or gas-like regime at 0.018