Differential classification of dense material in a three-product cyclone

A hydrocyclone with two concentric vortex finders, named the three-product cyclone, has been successfully tested in the Platinum industry for classifying UG2 ore which contains a high density chromite and a low density PGM carrying silica component. The low density silica reports to the overflow even when not sufficiently fine enough for flotation, which results in loss of recovery through over-size silica component material in the float feed. Results from industrial plant trials conducted using a 600 mm diameter three-product cyclone are presented. The three-product cyclone produced a middlings product containing the majority of the oversize silica that would normally report to the overflow. The middlings from the three-product cyclone represents a small percentage of the total cyclone feed and can be treated separately by fine screening to return the coarse silica to the mill for further grinding. (C) 2004 Elsevier Ltd. All rights reserved.