A computational fluid dynamics (CFD) model is proposed to describe the multiphase flow in a dense-medium cyclone (DMC). In this model, the volume of fluid (VOF) multiphase model is first used to determine the initial shape and position of the air core, and then the so called mixture model is employed to describe the flows of the medium, coal particles and air, where the turbulence is described by the Reynolds stress model. The validity of the proposed approach is established by the reasonably good agreement between the measured and calculated results in terms of separation efficiency. This model is then used to quantify the effects of the ratios of spigot to vortex finder diameters (U:O) and medium to coal volumes (M:C) on the standard DMC performance and the effects of M:C ratio and operating Head (given in equivalent diameters of the medium head) on the large diameter DMC performance. The results are shown to be generally comparable to those reported in the literature. The key phenomena predicted are explained by the calculated inner flows.
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