South Deep Gold Mine, South Africa
South Deep gold mine, in the Mpumalanga region of South Africa, is the second biggest gold mine in the world. It is the also the seventh deepest mine in the world with a depth of 2,995m below surface. It has a current mine life of 80 years.
The mine produced 77,800oz of gold during the June quarter of 2013. The production capacity is expected to rise to 800,000oz per year by 2016. The underground gold mine also has a huge resource base of uranium.
Mining at the deep-level mechanised South Deep gold mine commenced in 1961. Goldfields acquired the mine in 2006 and owns it through its subsidiary, Newshelf 899.
South Deep gold mine geology, reserves and resources
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.
Mining and ore processing at the South African mine
The underground mine uses a combination of conventional drift and bench and low-profile mining methods.
The Upper Elsburg reef, the main target region of the mine, is mined using fully mechanised drift and fill and long-hole stoping. The Ventersdorp Contact Reef is mined using mechanised low-profile mining.
Ore from underground is taken to the surface by a conveyor system using the ventilation shaft headgear discharge bin.
The semi-autogenous grinding mill present in the milling circuit is used for primary and secondary milling. Ore milling is done by the two overflow ball mills and the tailings are stored in the centralised tailings storage facility.
Gold is recovered using four Knelson concentrators. Gold adsorption is conducted by an eight-staged carousel-type carbon-in-pulp circuit. The processing plant has a current capacity of 220,000t per month, which is expected to increase to 330,000t.
Developing the world's second biggest gold mine
The deep gold mine extends across an area of 4,268ha. It operates a gold mine accessed through two shaft systems, including the 2,995m deep Twin shaft complex and the South Shaft complex.
The mine is further explored and categorised into four areas, namely Old Mine, Current Mine, Phase 1 and Phase 2. Old Mine region is situated above the 90 Level and is accessed through the South Shaft complex.
The Current Mine region lies between the 90 Level and 95 Level and is accessed through the Twin Shaft. South Deep mine phase one will extend to 3,075m below the surface, while phase two will extend to 3,500m depth.
Construction and infrastructure at South Deep mine
Construction activities at South Deep include installation of a tailings storage facility and deepening of the ventilation shaft. The works also include additions to the metallurgical plant to increase its capacity.
Planexion process control system was installed at the mine along with a two-vertical silo facility for the surge capacity.
Mine equipment includes trucks, ore passes, crushers, conveyors and shaft silos. An ice based underground cooling system will be installed by 2015.
Head gear was attached to the ventilation shaft and converted into a production shaft in order to increase the capacity.
Contractors involved with South Deep's development
Murray & Roberts was awarded the contract to provide backfilling technology for the South Deep gold mine.
Civcon was awarded the contract for construction of a brattice wall.
Hatch South Africa was awarded the contract to design and engineer the new steel headgear for the mine.
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