Gipronickel Institute Ltd

D. V. Lyalinov, Senior Researcher, e-mail: OVLal@nikel.spb.su
A. A. Lebedeva, Researcher
A. P. Vakhrusheva, Researcher, Laboratory of Raw Material Geological and Technological Studies

Uitkomst complex (South Africa) is the host rock of Ni—Cu sulphide and chromite mineralisation. Commercial sulphide ores are located in lower pyroxenites (the main mineralized zone, or MMZ ore body) and in chromite peridotites (peridotite chromite mineralized zone, or PCMZ ore body). Material composition of two mineralogical and metallurgical samples has been studied, using optical and scanning electron microscopy methods. Being the principal sulphide minerals, pyrrhotite, pentlandite and chalcopyrite form several texture varieties, namely: blebby, net-textured and disseminated ores. High nickel pentlandite mainly occurring as porphyry grains is the most valuable nickel-bearing mineral. Pyrrhotite and violarite also contain nickel. Pentlandite predominantly forms perphoritic isolations. Apart from less rich sulphide mineralization, PCMZ ore body contains chromite ore. The studied ore types are readily treated by flotation. However, fine intergrowths of sulphide and silicate minerals may cause deterioration of flotation performance.

1. Gauert C. D. K. Sulphide and oxide mineralisation in the Uitkomst Complex, South Africa : origin in a magma conduit. J. African Earth Sciences. 2001. Vol. 32, issue. 2. pp. 149–161.
2. Gauert C. D. K., Jordaan L. J., De Waal S. A., Wallmach T. Isotopic constraints on the source of sulphur for the base metal sulphides of the Uitkomst Complex, Badplaas, South Africa. South African Journal Geology (99). 1996. pp. 41–50.
4. Gauert C. D. K., De Waal S. A., Wallmach T. Geology of the Uitkomst Complex — an overview. J. African Earth Sciences. 1995. Vol. 12. pp. 108–126.
5. Gauert C. D. K., De Waal S. A., Wallmach T. Geology of the ultrabasic to basic Uitkomst complex, eastern Transvaal, South Africa : an overview. J. African Earth Sciences. 1995. Vol. 21, issue 4. pp. 553–570.
6. Li C., Ripley E. M., Maier W. D., Gomwe T. E. S. Olivine and sulfur isotopic compositions of the Uitkomst Ni—Cu sulfide ore-bearing complex, South Africa : evidence for sulfur contamination and multiple magma emplacements. Chemical Geology. 2002. Vol. 188, issue 3/4. pp. 149–159.
7. Bradford L., McInnes C. and etc. The development of the proposed milling circuit for the Nkomati main concentrator plant. Minerals Engineering. 1998. Vol. 11, issue 12. pp. 1103–1117.
8. Hornsey A. E. The genesis and evolution of the Nkomati Mine Ni-sulfide deposit, Mpumalanga Province, South Africa : thesis … MSc. Durban : University of Natal, 1999. 224 pp.
9. Sarkar A., Ripley E. and etc. Stable isotope, fluid inclusion, and mineral chemistry constraints on contamination and hydrothermal alteration in the Uitkomst Complex, South Africa. Chemical geology. 2008. Vol. 257, issue 1/2. pp. 129–138.