Methods to increase fine mineral recovery in the Mount Isa Mines lead/zinc concentrator

Abstract

Methods to increase the flotation rate of fine (-10 μm) galena relative to sphalerite contained in a lead process stream have been examined. These included separate conditioning and flotation of the fine and coarse particles, both in the presence and absence of High Intensity Conditioning (HIC). Size separation before conditioning and flotation was by conventional hydrocyclone, producing overflow (p 8o =10 μm) and underflow, (p 80 =80 μm) streams. Flotation of the separately treated fine particles was compared to that of the fine particles in the unclassified stream. The parameter examined was collector concentration. The rate o f galena flotation in the overflow stream was found to be inferior relative to that in the undertow stream, even at high collector concentrations to the overflow stream. However, galena flotation in the overflow stream was more selective against sphalerite than in the undertow stream. This was ascribed to greater levels of galena liberation in the finer stream. The rate of galena flotation in the undertow stream was reduced at high collector concentrations. This phenomenon was ascribed to removal of the fines causing the remaining coarse hydrophobic panicles to destabilise the froth. Separate conditioning was found to result in the selectivity of galena against sphalerite to be slightly inferior to the unclassified feed. This was due to poor galena/sphalerite selectivity in the undertow stream. The galena flotation rate increased in all streams with High Intensity Conditioning.