A mathematical model to characterize separation behavior of a spiral for processing iron ore using a mechanistic approach

Abstract

Spirals are probably the lowest capital cost mineral concentrator available today. Combined with their low operating cost, they have continued widespread use. An attempt has been made to develop a mathematical model to simulate the particle and flow behavior in a iron ore processing spiral. The modeling framework addresses three main components of the spiral process, namely, geometry of the spiral and its trough, fluid motion along the curvilinear path of the spiral and principal forces acting on a particle. These components have been integrated seamlessly by assuming that the particles eventually attain dynamic equilibrium in the forward longitudinal direction and static equilibrium in the transverse direction. The resulting force function provides a spectrum of the particles’ radial location on the trough according to their size and relative density. The model predicts relative density distribution as a function of equilibrium radial position for different particle sizes. It also computes particle size variation as a function of equilibrium radial position for various values of relative density. Sensitivities of radial equilibrium distribution of particle size and relative density with respect to pitch and width of the spiral and also mean flow depth have been analyzed. Simulation results have been validated and found to be in good agreement with published data. The model provides an analytical tool for better understanding of the separation behavior of particles in a spiral for processing iron ore.