Browsing by Author "Chetty, Deshenthree"

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    Geochemical fingerprinting of carbonate wall rock alteration at major base metal sulphide deposits in the Otavi Mountain Land, Namibia
    (1998) Chetty, Deshenthree; Frimmel, Hartwig E; Le Roex, Anton
    The Otavi Mountain Land is a base metal ore province in which base metal sulphide deposits are hosted by platform carbonates in a foreland fold-and-thrust belt on the northern edge of the PanAfrican Damara Belt. Deposits have been classified as the Berg Aukas- and Tsumeb- types, based on differences in ore association, stratigraphic position and geochemistry of ores and gangue carbonates. Mineralisation at each of these deposits is accompanied by carbonate alteration in the form of dolomite and calcite veins, carbonate recrystallisation, calcitisation and carbonate silicification. Optical cathodoluminescence imaging, electron probe micro analysis, X-ray fluorescence spectrometry, X-ray diffraction, high performance ion chromatography, proton probe micro analysis, stable isotope techniques, and fluid inclusion microthermometry were employed (i) to differentiate between carbonate generations associated with the alteration and mineralisation, particularly for the more economic Tsumeb-type deposits, represented by Tsumeb and Kombat, as well as in comparing between Berg Aukas- and Tsumeb-type deposits; (ii) to set constraints on the fluids effecting such alteration and associated mineralisation; (iii) to determine the relationship of the Khasib Springs deposit, for which little geochemical data exists, to deposits of the Tsumeb-type, and (iv) to identify those parameters which are diagnostic of Tsumeb-type mineralisation.
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    Mineralogical Factors Affecting the Dense Medium Separation of Nickel Sulfide Ores
    (2022-10-18) Pillay, Keshree; Mainza, Aubrey Njema; Chetty, Deshenthree; Becker, Megan
    Dense medium separation (DMS) is often used to reject a large portion of gangue material upfront to create cost and energy savings during processing. As lower-grade ores with complex mineralogy are being increasingly exploited, the properties of the gangue minerals begin to play a more important role in the upgrading of the ore. It is therefore important to understand these mineralogical factors to be able to select suitable processing routes for specific ore types. Two nickel sulfide deposits in southern Africa were chosen as case studies to understand differences in DMS efficiency when applied to different ores: Ore A and Ore B. Both ores showed nickel upgrades using DMS and the products were then characterized using QEMSCAN, with the aid of X-ray diffraction and electron probe microanalysis. Overall, particle density remains the main control on the separation, followed by sulfide texture, with massive and net-textured sulfides having larger grain sizes and therefore better liberation than disseminated sulfides. In addition to the concentration of sulfides, primary and secondary silicate minerals are separated by their density differences, which can affect the recovery of finely disseminated sulfides associated with them. Particle size is also important in DMS, with material near the cut-point density separating on size rather than density. The understanding of the mineralogical properties affecting DMS can aid in the prediction of the suitability of DMS for different ore types.