South Africa

Tshepong North Mine

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Overview

Mine TypeUnderground
Commodities
  • Gold
Mining Method
  • Undercut mining
  • Open stoping
  • Sequential grid mining
  • Breast stoping with strike pillars
Production Start... Lock
Mine Life2030
ShapshotTshepong North is a deep-level underground mining operation. Tshepong North ore is transported, by rail, from the shaft to the Harmony One Plant in Welkom for processing.

The Tshepong Operations were disaggregated into two separate CGUs being the Tshepong North CGU and the Tshepong South (Phakisa section) 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.
Related AssetTshepong South(Phakisa)

Owners

SourceSource
CompanyInterestOwnership
Harmony Gold Mining Company Ltd. (operator) 100 % Indirect
Tshepong North is wholly owned and operated by Harmony Gold.

Contractors

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Deposit type

  • Conglomerate hosted

Summary:

Tshepong North 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 North mining right area is also affected by the Ophir and Dagbreek faults.

Tshepong North exploited primarily the Basal Reef, which occurs within the Harmony Formation of the Johannesburg Subgroup of the CRG.

Mineralization also occurs within the stratigraphically higher A and B reefs of the Kimberley (formerly Aandenk) Formation, within the Turffontein subgroup of the CRG. However, only the B Reef can be economically extracted.

Mineralization is associated with the presence of medium to coarse, clast-supported oligomictic pebble horizons. The presence of allogenic pyrite and detrital carbon is also common.

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° with a general north- south strike. The Lower Cycle Black Chert facies predominates in the majority of the lease area. Reef consists of an oligomictic small pebble matrix-supported conglomerate lag with a fly-speck carbon contact with moderate to high grade value trends striking north-west south-east. The EN area of the mine consists of the Loraine facies which consist of small to medium upward fining polimictic matrix supported conglomerate with low to moderate grades. The rest of the reef package constitutes barren siliceous fine-grained reef quartzite. The entire reef package reaches up to 120cm thick and is overlain by 4-6m thick Khaki shale.

The Central Rand Group itself is overlain in turn by lavas and sediments of the Ventersdorp System and the more recent sediments of the Karoo Group.

The B Reef occurs approximately 145m stratigraphically above the Basal Reef and varies in thickness from 30cm to 170cm. The conglomerate varies in character depending on the facies, with B1 being a small to medium pebble conglomerate and usually no more than 30cm thick with abundant carbon. The B2 facies is a small pebble lag in an argillaceous quartzite, with little to no mineralisation. B3 facies is a 20 to 150cm thick conglomerate, mature, well packed, with pebble sizes varying from small to cobble size, very polymictic, normally with abundant pyrite and some carbon. This is the most common facies.

Reserves

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Mining Methods

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Comminution

Crushers and Mills

Milling equipment has not been reported.

Summary:

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.

Processing

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Production

Until 2021, all production and cost data are reported for Tshepong Operations, which was restructured, and from FY21 are reported separately as Tshepong North and Tshepong South.
CommodityUnits2024202320222021202020192018
Gold oz 00000000000000000000000000000000000000302,026 
All production numbers are expressed as metal in doré. ^ Guidance / Forecast.
* Combined production for Tshepong South(Phakisa) Mine and Tshepong North Mine

Operational metrics

Metrics202320222021202020192018
Tonnes milled 000000000000000001,716 kt

Production Costs

CommodityUnits202320222021202020192018
Cash costs Gold USD 0000 0000 0000 0000 1,103 / oz   987 / oz  
All-in sustaining costs (sold) Gold USD 0000 0000 0000 0000 1,396 / oz   1,245 / oz  

Financials

Units2024202320222021202020192018
Capital expenditures (planned) M USD  ....  Subscribe
Capital expenditures M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 78  
Revenue M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 419  
Gross profit M USD  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe  ....  Subscribe 123  

Heavy Mobile Equipment

Fleet data has not been reported.

Personnel

Mine Management

Source Source
Job TitleNamePhoneEmailProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Nov 9, 2023
....................... Subscription required ....................... Subscription required Subscription required Nov 9, 2023
....................... Subscription required ....................... Subscription required ........... Subscription required ........... Subscription required Subscription required Nov 9, 2023

EmployeesContractorsTotal WorkforceYear
Subscription required Subscription required Subscription required 2023
Subscription required Subscription required Subscription required 2022
Subscription required Subscription required Subscription required 2021
Subscription required Subscription required Subscription required 2020
Subscription required Subscription required Subscription required 2019
Subscription required Subscription required Subscription required 2018
Subscription required Subscription required Subscription required 2017

Aerial view:

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