Overview
Status | Care and Maintenance |
Mine Type | Open Pit & Underground |
Commodities |
- Nickel
- Copper
- Cobalt
- PGM
- 4E (Pt, Pd, Rh, Au)
|
Mining Method |
- Truck & Shovel / Loader
- Mechanized Cut & Fill
|
Processing |
|
Nkomati Mine was placed on care and maintenance in March 2021 in line with the strategy as planned and previously communicated. Nkomati Mine ceased mining in February 2021. The last ore was processed through the concentrator plant in March 2021. |
Source:
p. 36

ARM’s attributable beneficial interest in the Nkomati operation is 50%. The other 50% is held by Norilsk Nickel Africa (Pty) Ltd.
Summary:
Sulphide and chromite mineralisation occurs within the Uitkomst Complex, a Bushveld-age, layered, mafic-ultramafic intrusion, which concordantly intrudes dolomite/chert of the Malmani Subgroup and shales/quartzites of the Timeball Hill Formation. The Uitkomst Complex, which lies unconformably on an Archaean basement, is a north-west/south-east tubular shaped body which outcrops in the Slaaihoek Valley for approximately 9 kilometres before dipping at 4º below an escarpment where it has been drilled down-dip for another 4 kilometres and is still open-ended to the north west.
From the base to top, the stratigraphy of the Uitkomst Complex comprises the Basal Gabbro Unit (up to 15 metres thick), the Lower Pyroxenite Unit (average 35 metres), the Chromititic Peridotite Unit (30 to 60 metres), the Massive Chromitite Unit (up to 10 metres), the Peridotite Unit (330 metres), the Upper Pyroxenite Unit (65 metres), the Gabbronorite Unit (250 metres), and the Upper Gabbro Unit (50 metres). The complex and surrounding sediments are intruded by numerous diabase sills up to 30 metres in thickness.
Apart from the now mined-out Massive Sulphide Body (MSB), situated at and below the base of the Uitkomst Complex, there are three main economic sulphide mineralised zones:
-The Basal Mineralised Zone (BMZ) within the Basal Gabbro;
-The Main Mineralised Zone (MMZ) occurring within the Lower Pyroxenite Unit;
-The Chromititic Peridotite Mineralised Zone (PCMZ) which occurs with the Chromititic Peridotite (PCR).
In addition, the Peridotite Unit contains the Peridotite Mineralised Zone (PRDMZ) which is a low-grade disseminated sulphide mineralisation zone not yet included in the mine’s resource base. The dominant sulphide minerals are pyrrhotite, pentlandite and chalcopyrite. Cobalt is mostly in solid solution in the pentlandite, and the platinum group metals (PGMs) occur as separate minerals, with merenskyite being dominant. The current mined chromite is contained within the Massive Chromitite Unit (MCHR) in the open-pit area.
Mining Methods
- Truck & Shovel / Loader
- Mechanized Cut & Fill
Summary:
Mining operations comprise open-pit mining operation which feeds two concentrators (Main Mineralised Zone and Chromititic Peridotite Mineralised Zone) producing concentrate containing PGMs, nickel, copper and cobalt. Previously, MMZ was also mined by underground mechanised mining methods but this operation is now on care and maintenance.
Flow Sheet:
Crusher / Mill Type | Model | Size | Power | Quantity |
Gyratory crusher
|
.......................
|
|
|
1
|
Cone crusher
|
|
|
520 kW
|
2
|
AG mill
|
|
10.51m x 5.14m
|
|
1
|
Ball mill
|
|
7.01m x 9.46m
|
|
1
|
Ball mill
|
|
|
|
2
|
Summary:
The Main Mineralized Zone (MMZ) flow circuit design employed a fully autogenous (FAG) primary mill in closed circuit with a vibrating screen and pebble crushers. A secondary ball mill in closed circuit with cyclones supplies feed to the flotation circuit at SG 1.3-1.34, 70% -75 µm at 620 t/h.
Peridotitic Chromititic Mineralized zone (PCMZ) plant utilises conventional crushing and 2 stages of ball milling.
Flow Sheet:
Summary:
Two concentrators (Main Mineralized Zone plant and PCMZ) producing concentrate containing PGMs, nickel, copper and cobalt.
Main Mineralized Zone flotation circuit is a relatively standard rougher-cleaner-recleaner configuration. A combined nickel-copper-cobalt and PGM concentrate is collected from the recleaner. Currently the pyrrhotite scavengers function as extended rougher capacity.
Chrome products from Oxidised Massive Chromitite and the PCMZ, produced from the chrome washing plant and the PCMZ plant, are sold to local and export markets.
Recoveries & Grades:
Commodity | Parameter | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 |
Nickel
|
Head Grade, %
| ......  | ......  | ......  | 0.24 | 0.3 | 0.36 | 0.36 |
Reserves at June 30, 2021:
Key assumptions for Mineral Resources:
Grade cut-off Underground: 0.30% Ni MMZ (Main Mineralised Zone) and 0.30% Ni PCMZ (Chromititic Peridotite Mineralised Zone). Grade cut-off Open-pit: 0.16% Ni MMZ and 0.16% Ni PCMZ.
MMZ (Main Mineralised Zone) and PCMZ (Chromititic Peridotite Mineralised Zone) stockpile Mineral Resources: grade cut-off 0.16% Ni.
Category | OreType | Tonnage | Commodity | Grade |
Measured
|
|
72.89 Mt
|
Nickel
|
0.32 %
|
Measured
|
Stockpiles
|
0.34 Mt
|
Nickel
|
0.22 %
|
Measured
|
|
72.89 Mt
|
Copper
|
0.12 %
|
Measured
|
Stockpiles
|
0.34 Mt
|
Copper
|
0.08 %
|
Measured
|
|
72.89 Mt
|
Cobalt
|
0.02 %
|
Measured
|
Stockpiles
|
0.34 Mt
|
Cobalt
|
0.01 %
|
Measured
|
|
72.89 Mt
|
4E (Pt, Pd, Rh, Au)
|
0.89 g/t
|
Measured
|
Stockpiles
|
0.34 Mt
|
4E (Pt, Pd, Rh, Au)
|
0.63 g/t
|
Indicated
|
|
94.62 Mt
|
Nickel
|
0.37 %
|
Indicated
|
|
94.62 Mt
|
Copper
|
0.15 %
|
Indicated
|
|
94.62 Mt
|
Cobalt
|
0.02 %
|
Indicated
|
|
94.62 Mt
|
4E (Pt, Pd, Rh, Au)
|
0.98 g/t
|
Measured & Indicated
|
|
167.51 Mt
|
Nickel
|
0.35 %
|
Measured & Indicated
|
|
167.51 Mt
|
Copper
|
0.14 %
|
Measured & Indicated
|
|
167.51 Mt
|
Cobalt
|
0.02 %
|
Measured & Indicated
|
|
167.51 Mt
|
4E (Pt, Pd, Rh, Au)
|
0.94 g/t
|
Inferred
|
|
46.35 Mt
|
Nickel
|
0.4 %
|
Inferred
|
|
46.35 Mt
|
Copper
|
0.13 %
|
Inferred
|
|
46.35 Mt
|
Cobalt
|
0.02 %
|
Inferred
|
|
46.35 Mt
|
4E (Pt, Pd, Rh, Au)
|
0.97 g/t
|
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