Modelling dense particle streams during free-fall electrostatic separation

Electrostatic particle separation is an attractive option for dry processing in the resource and recycling industries. Free-fall electrostatic separators are particularly simple and versatile member of this family of technologies. This paper presents numerical simulations of the movement of particles with different charges and masses within a stream of other particles in an electric field. The modelled system comprises much larger numbers and higher spatial densities of particles than previous models, and allows a realistic assessment of the effect of interparticle electrostatic forces and collisions. The effect of an angled feed with both co- and counter-directional fields is investigated, and the results translated to grade-recovery curves for different configurations. Among the important results were the degradation of separation performance with particle feed rate, the potential importance of Coulombic interparticle reactions in dense particle streams, and the benefits of an angled feed with a counter-directional electric field.