A geometallurgical assessment of the geological and mineralogical influences on flotation performance at the Nkomati Nickel Mine, Mpumalanga, South Africa

Abstract: The Uitkomst Complex is a Bushveld-age, layered body that intruded into the basal sediments of the Transvaal Supergroup. The complex is cogenetic with the Rustenburg Layered Suite (RLS) of the Bushveld Complex. Mafic-ultramafic rocks of the complex host sulfide mineralisation. The main target element for mining is nickel (Ni), which is recovered by a bulk flotation process. Nkomati mine also produces copper (Cu), cobalt (Co) and platinum group metals (PGEs) as by-products. This study provides a geometallurgical assessment of different ore variants associated with the main mineralised zone at Pit 3 of the Nkomati mine. Geometallurgical assessment provide an opportunity for improving mineral processing performance in existing concentrators and for describing the undeveloped ore bodies. A detailed geometallurgical study also contributes to better control and planning at the processing plant. Optimum results can be achieved by scheduling the most appropriate combination and sequence of material-type to the feed. In such instances, geometallurgy could be considered as an extension of the mine-to-mill process. A comprehensive understanding of the ore mineralogy is the key to understanding the flotation response of various minerals in an ore body. Ore characterisation is the first step for success of any geometallurgical study. Detailed mineralogical characterisation of ore is one of the most essential steps in this process; this requires a detailed investigation of the ore body in terms of modal mineralogy, liberation potential, and grain-size distribution. For this, 29 samples from four representative boreholes were used to determine the influence of mineralogy on flotation response at the Pit 3 ore body. Optical microscopy, Mineral Liberation Analyser (MLA), and X-ray diffraction (XRD) were used extensively for mineralogical characterisation of these samples. Upon detailed ore characterisation, it was observed that textural variations of sulfide mineralisation in the studied samples depend on host rock types, grain...D.Phil. (Geology