COMPUTATIONAL SIMULATION OF FLUID AND DILUTE PARTICULATE FLOWS ON SPIRAL CONCENTRATORS

Spiral separators are used globally in the fine coal and heavy mineral processing industries as gravity-concentration devices. Consisting of an open trough that spirals vertically downwards in helix configurati on about a central axis, a slurry mix of particles and water is fed to the top of the concentrator. Particles are then separated radially on the basis of density and size as they gravitate downwards. To enhance performance, the geometric design has evolved historically by experim ental trial-and-error investigations to develop a prototype suited to the given industrial application. This approach has proved somewhat pr ohibitive for design purposes however, and researchers have accordingl y turned to numerical techniques in an attempt to develop a fully pred ictive and reliable model for use in the design process. Towards this end, the present paper uses Computational Fluid Dynamics (CFD) analysi s to simulate fluid and dilute particulate flows on one operational sp iral unit. The free-surface Volume-of-Fluid (VOF) algorithm, isotropic RNG k-epsilon turbulence model and Lagrangian method have been used f or this purpose. Satisfactory predictions have been obtained with resp ect to a collaborative experimental program, and the model forms the b asis for future examination of the two-way fluid-particle coupling pro cesses and inter-particle effects. (C) 1998 Elsevier Science Inc. All rights reserved.