Advanced Media-Free Fine and Ultra-Fine Grinding –The Kelsey Axial Displacement Mill

摘要

The Autogenous Kelsey Axial Displacement (KAD) mill is essentially a short retention timerncentrifugal mill, designed to effectively harness extraordinarily high concentrations of input energyrnfor efficient particle size reduction. The mill which has an operating duty band extending fromrnprimary to ultra-fine also has the unique capacity to generate fine and ultra-fine products from singlernstage size reductions of either coarse or fine mineral feeds, in both wet or dry operating modes. Thisrnpaper covers developments following a recent optimisation programme which confirmed that millrnshell speed and the velocity differential between the shell and the rotating internal disc assembly tipsrncould be optimised in relation to specific energy for a given feed rate and feed size providing thernproduct size remains constant. Subsequent test-work further demonstrated the versatility of the millrnwith duties ranging from the removal of surface contamination associated with heavy mineralrnconcentrate particles to the production of premium ultra-fine talc, from a single stage of sizernreduction. Open circuit grinding of a rougher gravity concentrate to liberate gold ahead of leachingrnalso highlighted the scope for the application of low cost KAD milling for a range ofrnhydrometallurgical feed preparation duties, which involve fine and ultra-fine grinding.