Overview
Stage | Production |
Mine Type | Underground |
Commodities |
|
Mining Method |
- Scattered stoping
- Sequential grid mining
- Undercut mining
|
Production Start | ... |
Mine Life | 7 years (as of Jan 1, 2023) |
Tshepong South mine is a mature, moderate to deep-level underground operation using conventional underground mining methods. Ore mined is processed at the Harmony One plant, with gold recovered using the gold cyanide leaching process.
The Tshepong Operations were disaggregated into two separate CGUs being the Tshepong North CGU and the Tshepong South(Phakisa) CGU, for impairment testing at 30 June 2022. This was due to the decision taken during the FY23 budget process in June 2022, to reinvest in the two individual operations to maximise individual profitability following the change to Tshepong North's life-of-mine with the sub-75 decline project being halted. Based on the forwardlooking nature of the impairment assessment, a separate impairment calculation was prepared for each of the CGUs. Tshepong North and Tshepong South are disclosed as separate reportable segments for the 2023 financial year, therefore the disclosures for 2022 and 2021 have been re-presented accordingly. |
Source:
p. 58
Tshepong South (Phakisa) is wholly owned and operated by Harmony Gold.
Contractors
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Summary:
shepong South is situated in the Free State Goldfield, on the southwestern margin of the Witwatersrand Basin of South Africa, one of the most prominent gold provinces in the world. The major gold bearing conglomerate reefs are mostly confined to the CRG of the Witwatersrand Supergroup.
The general orientation of the Witwatersrand Supergroup succession in this goldfield is interpreted as north-trending, within a syncline that is plunging to the north. The syncline has been divided by faults into the Odendaalsrus, Central Horst and Virginia sections. The Tshepong South mining right area is also affected by the Tribute fault (~270m) and Arrarat Fault (~180m) to the far south-east of the shaft.
The principal gold-bearing orebody is the stratiform and strata-bound Basal Reef (known as the Basal Reef Zone or BRZ). This unit comprises a thin conglomerate at the base of the BRZ, overlain by clean “placer” quartzites. The Basal Reef is underlain by a thick series of siliceous and argillaceous quartzites comprising the Welkom formation and overlain by shales and quartzites of the Harmony formation, both of the Johannesburg sub-group of the Central Rand Group. Although not apparent within the mine lease area, the Basal Reef sits unconformably on the Welkom formation.
The Basal Reef dips towards the east at 25° in the north and up to 45° in the south. The Lower Cycle Black Chert facies predominates in the north with a north-west south-east value trend. Th ........
Mining Methods
- Scattered stoping
- Sequential grid mining
- Undercut mining
Summary:
Tshepong South may be classified as moderate to deep level underground gold mine currently operating at depths of up to 2,427m below surface.
The orebody at Tshepong South Mine is broken up into blocks by geological structures with large throws. Due to the orebody being broken up into these small blocks, a Scattered mining method is used at Tshepong South Mine. Scattered mining is when mining is done between the major geological structures. The mine design criteria is based on the sequential grid mining method where the crosscuts are spaced at fixed distance of 160m however additional development can be required in some instances and/or crosscut spacing reduced/increased depending on the prevailing geological structures. Primary Waste Development is done ahead of the stoping front in the virgin stress environment.
The shaft’s primary economic reef horizon is the Basal Reef that is extracted both by undercut mining (North), leaving a quartzite beam in the Hangingwall to ensure the stability of the overlaying shale and open mining (South).The Basal Reef is mined conventionally from a single shaft barrel reaching a depth of 2 600m below collar. The orebody is broken up into blocks by geological structures with large throws. Due to this a Scattered Mining Method is used. Scattered mining is when mining is done between the major geological structures. The mine design criteria is based on the Sequential Grid mining method where the crosscuts are spaced at fixe ........
Flow Sheet:
Source:
Ore Reception:
The use of parallel processing starts at the ore receive bin, where there are two unloading stations for the railcars that bring the ore in from the various shafts and rock dumps. A unique feature of the Plant is the Ore Reception facility, which has been designed to eliminate dead storage space, a serious constraint in railway ore storage bins. Ore is transported by rail to the Plant. The railway hoppers discharge individually into one of the two concrete, rail-lined inverted cones, 12m in diameter and 8m deep. The apex of the cone is 57o. The ore is rapidly withdrawn from the apex of the cone via a shuttle belt feed conveyor feeding onto a main silo feed conveyor. The twelve ore storage silos are constructed from concrete and are also rail-lined. Each silo has a live storage of approximately 3 000 tons. Ore is discharged onto the mill feed conveyor via a pneumatically-operated Langlaagte chute. When filled to full capacity, the twelve ore silos provide approximately 60 hours storage for the six Run-of-Mine (ROM) mills.
There are six parallel and independent milling lines with each one having a conveyor running underneath 2 silos (A and B) and taking the ore up into one of the six run-ofmine (ROM) mills. Generally, ore is drawn only from one of the two silos for each mill whilst the other is being filled with ore. Hence, one silo is discharging onto the mill feed belt, and the other refilled.
Milling:
The ore is taken up the slow-moving conveyers from underneath the silos and discharged directly into the feed hopper for the ROM (Run Of Mine) mills. Fully autogenous (FAG) milling is a milling process in which the entire ROM ore stream is fed directly into the mills. The grinding media is generated within the mill from suitably sized pieces of ROM ore itself, supplemented by waste rock dump material. The feed rate to the mills is between 90 and a 100t/h.
The milling circuit consists of six single stage ROM mills that are controlled on maximum power, utilising programmable logic controllers (PLCs). Variations in mill load are measured by load cells situated under the outlet trunnion bearings. Each ROM mill is 4.9m diameter by 10m long and powered by 3.3MW motors and grinds the ore to between 68 and 73% minus 75µm.
For control purposes, the mill feed belts and the mill discharge pumps both have variable speed drives. Each mill is in closed circuit with a 1200mm primary cyclone with mass flow measurement on the feed. The primary cyclone overflow is screened on a 600µm linear screen for the removal of coarse woodchips and tramp steel. This has the purpose of preventing gold losses and carbon contamination in the downstream CIP circuit. Cyclone overflow, which has a low density, is pumped out to the thickeners. The current cyclone overflow size is 68% at -75µm.
Flow Sheet:
Summary:
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Reserves at June 30, 2023:
The Mineral Resources are reported using a cut-off value of 780cmg/t determined at a 90% profit guidance, and a gold price of US$1,764/oz.
The Mineral Reserves are reported using a cut-off grade of 791cmg/t determined using a gold price of US$1,582/oz gold.
Mineral Resources are reported inclusive of Mineral Reserves.
Category | Tonnage | Commodity | Grade | Contained Metal |
Proven
|
2.9 Mt
|
Gold
|
7.79 g/t
|
722 koz
|
Probable
|
0.6 Mt
|
Gold
|
7.06 g/t
|
128 koz
|
Proven & Probable
|
3.4 Mt
|
Gold
|
7.67 g/t
|
850 koz
|
Measured
|
8 Mt
|
Gold
|
12.69 g/t
|
3,252 koz
|
Indicated
|
7.1 Mt
|
Gold
|
11.61 g/t
|
2,662 koz
|
Inferred
|
25.1 Mt
|
Gold
|
10.67 g/t
|
8,606 koz
|
Total Resource
|
40.2 Mt
|
Gold
|
11.24 g/t
|
14,520 koz
|
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