PARTICLE AND FLUID MOTION ON SPIRAL SEPARATORS

Techniques for predicting the primary fluid flow profile and the secondary circulation on spiral troughs are summarised and revised equations for calculating the flow velocities are presented. Recent experimental studies of the fluid motion at both the trough base and the free surface are reported and compared with the predicted tracks of fluid elements at various positions within the flow. The use of a trajectory approach to estimate the motion and distribution of particles across the trough during a separation is reviewed, and the problems associated with the comparison of hydrodynamic data with measured results expressed in terms of sieve apertures are discussed. A suitable correlation technique is proposed and applied to preliminary results from a fundamental study of the behaviour of individual size fractions of glass spheres and quartz sand. The predicted recoveries of a gold ore on three different spiral separators are also compared with measured results on a size by size basis.