South Deep gold mine which was formerly named Western Areas Gold Mine located in some 45 kilometers south-west of Johannesburg, in the districts of Westonaria and Vanderbijl park in the Gauteng province region of South Africa. South Deep gold mine has a depth of 2,995m below the surface, and is the world's deepest mines. South Deep gold mine in South Africa held by Newshelf 899 Proprietary Limited (Newshelf) which is a 90% subsidiary of Gold Fields Limited and the remaining 10% is held by outside shareholders as part of the BBBEE transaction.
The South Deep Gold Mine lies at the northwestern edge of the Witwatersrand Basin, known as the West Rand Goldfield. The property covers an area of 2,469 hectares of surface (freehold) land and 3,563 hectares.
South deep mine is located in the Far West Rand Goldfields and forms a part of the Witwatersrand Basin. The mine deposits lies beneath the Karoo Supergroup, Chuniesoort Group, Pretoria Group, Klipriviersberg Group and the Central Rand Group.
The Central Rand group comprises of detrital sedimentary rocks filled with quartz-pebble conglomerates. The gold deposits are interrelated with sedimentary features such as unconformities and fluvial channels.
The South Deep deposit has approximately 39.1Moz of gold reserves. The estimated uranium inventory at the mine is 37.5Mlb.
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| Mineral deposit in South Deep gold mine region of South Africa |
The Central Rand group comprises of detrital sedimentary rocks filled with quartz-pebble conglomerates. The gold deposits are interrelated with sedimentary features such as unconformities and fluvial channels.
The South Deep deposit has approximately 39.1Moz of gold reserves. The estimated uranium inventory at the mine is 37.5Mlb.
The South Deep gold mine has been divided into 3 main areas. “New Mine” extends from 100 level down to 110 level. The North of Wrench area extends from a depth of 2,700 metres to 2,900 metres and the South of Wrench area extends to a final depth of 3,300 metres. “Old Mine” comprises the area above 87 level, and is serviced from the South Shaft Complex. “Current Mine”, which is serviced from the Twin and South Shafts, extends from 87 level to 95 level.
South Deep Gold Mine is an intermediate to deep level gold mine comprising two shaft systems that mine various auriferous conglomerates from open ground and pillars that occur at depths between 1,575 m and 3,500 m below surface, exploiting auriferous palaeoplacers (reefs), namely the conglomerates that comprise the Upper Elsburg Reefs of the Mondeor Formation. The shaft systems comprise the older South Shaft complex with its main shaft and two sub vertical shafts, and the newer flagship complex, known as Twin Shafts. Ore is processed at a central metallurgical plant. The mining rights comprise a total of 3,566 ha.
MINING METHODS IN SOUTH DEEP GOLD MINE SOUTH AFRICA
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| Underground mine in South Deep gold mine region of South Africa |
The Ventersdorp Contact Reef ( VCR ) will be mined by a low profile mechanised mining method, whereas the Upper Elsburgs will be mined by a variety of mining methods ranging from mechanised drift-and-fill or modified drift-and-bench to longhole stoping. Ore is drilled with trackless twin boom, blasted and taken by Load-Haul- Dumpers (LHDs) to internal ore passes for transport to hoisting shafts.
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| Drilling activity in the mining South Deep Gold mine in South Africa |
The Upper Elsburg Massives are the main target horizon and the extraction thereof will be done with the aid of mechanised mining equipment after completion of the de-stress mining.
Two alternative mining methods are under review in 2015 at South Deep Gold Mine in South Africa. The first method is the 4.5m X 4.5m destress method and the second is the Inclined Mining Slot method. Both of these methods, if successful, could assist in de-risking the South Deep mine buildup plan and future production profiles, and could also have a meaningful positive impact on mining costs.
South Deep is a mine that has now been built to extract one of the largest known gold ore bodies in the world. The 38 Moz Mineral Reserve is underpinned by well understood ore body model and all key required infrastructure is now installed to deliver the mine as a low cost, long life mechanised mining operation. Due to its deep level and fully mechanised nature, South Deep has no real benchmark operation in the industry and the current focus therefore remains on establishing the basics at the mine to drive productivity and leverage unit costs.
GOLD PROCESSING AT SOUTH DEEP GOLD MINE IN SOUTH AFRICA
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| Gold plant in South Deep Gold Mine |
Autogenous Grinding (SAG) Mill and overflow Ball Mill stage of a process of destruction of mineral rock, which is then made into pulp. Processing of mineral ores from this stage then, heading into the dissolution process gold ore into the leach tank circuit. The leach circuit has six mechanically agitated tanks each with a 3,000 m3 volume.
Gold dissolution is achieved with the use of cyanide with lime being added to pulp ensure protective alkalinity. In South Deep mine has an eight stage carousel type Carbon In Pulp circuit with 200 m3 tanks for gold absorption using carbon.
Carbon stripping is achieved using the AARL elution system and carbon regeneration is carried out in a rotary kiln at a rate of 500 kg/hr.
For gold recovery from solution in South Deep gold mine is by electrowinning system using the Kemix Sludge Reactors, followed by drying concentrat and then smelting in an induction furnace to produce gold bullion.
Both mill and cyanide bars are then marked appropriately and dispatched to Rand Refinery via helicopter. Installed processing capacity is 220 ktpm with modular expansion to 330 ktpm planned in the original design.
South Deep Gold Mine is the sole remaining gold mine in the South Africa Region following the unbundling of the legacy operations into Sibanye Gold Limited. South Deep is a king-pin asset in Gold Fields and represents one of the last mega-projects to be built that exploits gold in the West Wits goldfields.
The mechanised mine is still in the production ramp-up phase and execution of the defined build-up will deliver a steady state run rate of 300-330 ktpm and 650-700 koz of gold per annum at an estimated AIC of circa US$900/oz.
The top of the starter wall will be reached by mid-2018 and the end of phase 1 by mid-2020. The construction of phase 2 needs to commence in early 2018 and the main penstock needs to be in place by 2029. South Deep Gold Mine is estimated that the current Mineral Reserves will be depleted in 2087 (73 years).
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