"Impact of Mineralogical Variation on the Smelting of Cu-Ni-PGM Concentrates"

"In the platinum group metals (PGM) industry, smelters are often perceived as ‘black boxes’ that have to process concentrates of variable mineralogy and originating from multiple mines operating along strike or downdip from each other in the same geographical region, as is the case in the Western Bushveld of South Africa. However, PGM smelter complexes are much more sensitive to concentrate blend variation than most metallurgists or geologists would anticipate.This paper will review the impact of concentrate blends deriving from a number of concentrators processing ores from the Bushveld Igneous Complex (BIC) on smelting and converting behaviour and the constraints they impose upon smelter operation. Significant variation in behaviour is not only noted between the main mineralisation types, namely the Merensky and Upper Group 2 (UG2) reefs, but also within a given reef type. Due to the way PGMs are mineralised and finely disseminated, concentrators have to grind concentrates ultra-fine to liberate the PGMs and provide a sufficiently high-grade concentrate for smelting.The chemistry and mineralogy of the concentrates vary with the type of mine (open pit versus underground), the reef type and varies along strike; this variation impacts numerous key smelter parameters such as the base metals content, the matte fall, the converter aisle capacity, sulfur dioxide gas production, furnace matte and slag temperatures, and the accumulation of high smelting chromite-spinel minerals that has led to significant smelter upset conditions such as catastrophic furnace hearth and sidewall failures.Due to the production intensity of smelting, ie its high rate of processing per unit volume, smelters have been found to be far more sensitive to rapid variation in concentrate properties, highlighting the need for adequate blend control.CITATION:Eksteen, J J, 2016. Impact of Mineralogical Variation on the Smelting of Cu-Ni-PGM Concentrates, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 321–326 (The Australasian Institute of Mining and Metallurgy: Melbourne)."