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Open AccessArticle

A Process Mineralogical Evaluation of Chromite at the Nkomati Nickel Mine, Uitkomst Complex, South Africa

1
Department of Geology, University of Johannesburg, Auckland Park, Kingsway Campus, Gauteng 2006, South Africa
2
Department of Metallurgy, University of Johannesburg, Doornfontein Campus, Gauteng 2028, South Africa
*
Author to whom correspondence should be addressed.
Present Address: Department of Geosciences, Midlands State University, Private Bag 9055, Senga Road, Gweru, Zimbabwe.
Minerals 2020, 10(8), 709; https://doi.org/10.3390/min10080709
Received: 21 June 2020 / Revised: 22 July 2020 / Accepted: 23 July 2020 / Published: 12 August 2020
(This article belongs to the Section Mineral Processing and Extractive Metallurgy)
A process mineralogical study based on three texturally and mineralogically different chromite-bearing ore types at the Nkomati nickel mine was undertaken, with focus on chromite. Chromite is a by-product of the Ni-Cu-Co-PGE ore at Nkomati Nickel mine. These being the PCMZ_MG (medium-grade Ni-Cu sulphide silicate ore with disseminated chromite), PCMZ_HG (high-grade Ni-Cu sulphide silicate ore containing disseminated chromite) and MCHR (massive chromite unit) ore types. These were processed using benchtop flotation followed by gravity concentration using a shaking table at different grind sizes. Quantitative mineralogical data was obtained using a 600F Mineral Liberation Analyser for the unprocessed and processed ores at three selected target grinds. The Mineral Liberation Analyser data indicated that increased milling does not relate to increased chromite grades and recoveries, particularly for the disseminated PCMZ type ores based on laboratory-scale gravity concentration. The recovery is controlled largely by the chromite chemistry. The results also showed that the MCHR samples that underwent a pre-flotation stage before gravity separation had better Cr2O3 grades (45% to 47%) and recoveries (52% to 61%) than MCHR ore that did not undergo a pre-flotation stage, which recorded grades ranging from 44% to 46% and recoveries ranging from 43% to 60%. This holds promise for the blending of MCHR ores with the PCMZ ores. The PCMZ ores also displayed better Cr2O3 grades and recoveries at coarser grinds. The optimal target grind to process all three ore types is a P80 of 75 μm, which is the current grind size employed at Nkomati Nickel mine. Due to the low nickel price and grade the Nkomati Nickel mine is currently under care and maintenance. View Full-Text
Keywords: Nkomati nickel mine; chromite; process mineralogy; grind sizes; gravity separation; recovery; Uitkomst Complex Nkomati nickel mine; chromite; process mineralogy; grind sizes; gravity separation; recovery; Uitkomst Complex
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MDPI and ACS Style

Dzvinamurungu, T.; Rose, D.H.; Viljoen, K.S.; Mulaba-Bafubiandi, A.F. A Process Mineralogical Evaluation of Chromite at the Nkomati Nickel Mine, Uitkomst Complex, South Africa. Minerals 2020, 10, 709. https://doi.org/10.3390/min10080709

AMA Style

Dzvinamurungu T, Rose DH, Viljoen KS, Mulaba-Bafubiandi AF. A Process Mineralogical Evaluation of Chromite at the Nkomati Nickel Mine, Uitkomst Complex, South Africa. Minerals. 2020; 10(8):709. https://doi.org/10.3390/min10080709

Chicago/Turabian Style

Dzvinamurungu, Thomas; Rose, Derek H.; Viljoen, Karel S.; Mulaba-Bafubiandi, Antoine F. 2020. "A Process Mineralogical Evaluation of Chromite at the Nkomati Nickel Mine, Uitkomst Complex, South Africa" Minerals 10, no. 8: 709. https://doi.org/10.3390/min10080709

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