The origin of unusual cyclone performance curves

Abstract

The performance of primary and secondary cyclones was measured at three Canadian concentrators treating massive sulphides, viz.: Brunswick Mining and Smelting; Mines du lac Matagami (division of Noranda Mines), and Ruttan (Sheritt Gordon Mines). The primary cyclone performance curve had the expected shape, but in each case the secondary cyclone performance curve showed a dip in the size range 350 to 150 μm. This unusual curve was shown to arise from classification of minerals of different density and different size distribution. The feed to the secondary cyclone was modified by the primary so that the less dense component was markedly coarser than the more dense component. The conditions giving rise to these unusual curves are delineated. Some uses of the findings of interest to the mill metallurgist are outlined. Contemplated circuit changes involving series cycloning should consider the possibility of such unusual cyclone performance curves.