Browsing by Author "Pillay, Keshree"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Open Access
    Mineralogical effects on the dense medium separation of low grade nickel sulfide ore
    (2015) Pillay, Keshree; Becker, Megan; Chetty, Desh
    Dense medium separation (DMS) is a method often used to upgrade base metal sulfide (BMS) ores before their main processing stage, with varying results achieved for different ore types. The process makes use of the density differences between the BMS minerals and the lower density silicate/carbonate gangue minerals, using a separating medium of density between the two ore components. The separation is accelerated using a dense medium cyclone (DMC) to form two products: overflow (tailings) and underflow (concentrate). The purpose of DMS is to reject large quantities of gangue upfront, resulting in reduced time, energy and costs associated with processes such as milling and flotation. Preconcentration of ores using physical methods such as DMS is becoming an important consideration as lower grade ores are mined, to increase the feasibility of mining such ores. Two nickel sulfide deposits were chosen as case studies in order to understand differences in DMS efficiency for different ores. The first is the Main Mineralised Zone (MMZ) of the Nkomati Nickel deposit in Mpumalanga, South Africa, which is part of the Uitkomst Complex. The Phoenix deposit is also considered, and forms part of the Tati greenstone belt in eastern Botswana. Both deposits are magmatic Cu-Ni-PGE (platinum group element) deposits with similar sulfide mineralogy and pentlandite as the main nickel host. A process mineralogy approach was used to evaluate samples of both ores, describing the differences in the mineralogical properties within the overflow and underflow of each ore in order to understand the extent to which individual properties affect the separation.
  • No Thumbnail Available
    Item
    Open Access
    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.