Name: TauTona mine.
Location: The mine is situated on the West Wits line, south of Carletonville, in South Africa’s North West province, about 70 km south-west of Johannesburg.
Controlling Company: AngloGold Ashanti.
Brief Description: TauTona, which includes Savuka, is a mature deep-level underground gold mine with a limited life-of-mine. Mining is undertaken predominantly on the Carbon Leader reef (CLR) horizon, with TauTona mining towards the boundary of Sibanye Gold’s Driefontein gold mine.
Brief History: Sinking operations began at TauTona in 1957 and stoping operations on the Ventersdorp Contact reef (VCR) horizon in 1961. The mine has a three-shaft system, comprising a main, subvertical and tertiary vertical shaft. Mining at this operation is undertaken at depths ranging from 2 900 m to 3 480 m. Savuka was included in the TauTona operations in 2013.
Products: Gold and by-products of uranium.
Geology/Mineralisation: The CLR is the principal economic horizon at TauTona and the VCR is the secondary economic horizon. The CLR is located near the base of the Johannesburg subgroup, which forms part of the Central Rand group. The Central Rand group sediments are unconformably overlain by the Klipriviersberg lavas and the VCR is developed at the interface between the Central Rand group sediment and the overlying lavas. The CLR and the VCR at TauTona are vertically separated by about 900 m of shales and quartzites.
The CLR is a thin, on average 20-cm-thick, tabular, auriferous quartz pebble conglomerate and comprises three sedimentary facies or units. Economically, the most important is Unit 1, which is present as a sheet-like deposit over the whole mine, although reef development and grades tend to decrease rapidly where Unit 1 overlies Unit 2.
Unit 2 is a complex channel deposit that is present only along the eastern-most limit of current mining at TauTona. The Unit 2 CLR may be more than 2 m thick.
Unit 3 is preserved below Unit 1 in the southern parts of TauTona and is the oldest of the CLR conglomerates.
All production on the VCR at TauTona ceased in 2013 and no future mining has been planned on this reef horizon.
The CLR and VCR are cross-cut and displaced by faults and intrusive dykes and sills of various ages. The faulting, in conjunction with the many intrusives that displace and intersect these reefs, is responsible for most of the risk inherent in deep-level gold mining, since seismicity is associated with these geological features.
Reserves: Proven and probable reserves as at December 31, 2015, were estimated at 4.14-million tonnes, grading 7.91 g/t of gold.
Resources: Exclusive mineral resources as at December 31, 2015, were estimated at 2.77-million tonnes, grading 22.84 g/t of gold.
Mining Method: In the past, longwall mining was the only mining method used at TauTona, but it was decided to move from longwall mining to scattered grid mining, owing to the risk associated with mining through geological structures with longwall panels.
At Savuka, two new raise lines will be mined from a mini-long wall configuration to reduce the ore reserve development capital requirements.
Major Infrastructure and Equipment: Ore is initially ground using semiautogenous milling, after which a conventional gold-leach process, incorporating liquid oxygen injection, is applied. The gold is then extracted using carbon-in-pulp technology. The plant conducts electrowinning and smelting (induction furnaces).
Prospects: A drilling programme was initiated in late 2012 to explore the ground south of the Pretorius fault zone (PFZ). Its aim was to create a greater understanding of the lateral move- ment of the PFZ and the different intrusions south of the PFZ, their age relationships and different characteristics.
Drilling continues as mining advances and the database is updated accordingly.
The drilling programme will continue this year with additional interpretations and modelling of the structures south of the PFZ when required. Long inclined borehole drilling is scheduled to drill through some of the structures further south of the PFZ, which will also assist the interpreting and modelling of these structures.
Contact Person: Senior VP investor relations and group communications – global Stewart Bailey.
Contact Details:
AngloGold Ashanti,
tel + 27 11 637 6000,
email sbailey@anglogoldashanti.com, and
website http://www.anglogoldashanti.com.