TauTona

Overview

TauTona lies on the West Wits Line, just south of Carletonville in the North West Province and about 70km southwest of Johannesburg. The mine is part of Anglogold Ashanti's West Wits operations which also comprises the Savuka and Mponeng mining operations. 

Mining at TauTona takes place at depths of 2,000 m to 3,640m. The mine has a three-shaft system, supported by secondary and tertiary shafts and is in the process of converting from longwall mining to scattered-grid mining. This change in mining method was necessitated by the increased incidence of complex geology and the unsuitability of the current method for mining through the Pretorius fault. The change will also lead to improved safety.

TauTona shares a processing plant with Savuka. The facility currently has a monthly capacity of 180,000t and uses conventional milling to crush the ore and a carbon-in-pulp (CIP) plant to treat it. Once the carbon has been removed from the ore, it is transported to the gold plant at Mponeng for elution electro-winning, smelting and the final recovery of the gold.

TauTona lies on the West Wits Line, just south of Carletonville in Gauteng and about 70km southwest of Johannesburg in South Africa.

The name Gauteng comes from the Sesotho word meaning "Place of Gold", referring to the thriving gold industry of the area following the 1866 discovery of gold in Johannesburg. The climate is mostly influenced by altitude.

Geology & Mineralization

Two reef horizons are exploited at the West Wits operations the Carbon Leader Reef (CLR) situated near the base of the Central Rand Group and the Ventersdorp Contact Reef (VCR) which is situated 900 m above the CLR.

The CLR lies on a shallow-dipping unconformity and is a laterally continuous, oligomictic, small-to-medium pebble conglomerate and which is on average 20 cm thick. Channel widths vary from a few centimetres to a little over one metre. The CLR is underlain by 10 m of coarse-grained quartzite, with locally discontinuous pebble bands, the base of which is marked by the North Leader Reef.

The strata overlying the CLR comprise a 1.8 m thick band of light grey, crossbedded quartzites, which are in turn overlain by the 'green bar' (a chloritoid-rich siltstone). Flat-faulting frequently marks the base of the green bar.

The VCR is comprised of a quartz pebble conglomerate (up to 2m thick) capping the top-most angular unconformity of the Witwatersrand Supergroup. The topography of the VCR depositional area is uneven and the reef is draped over a series of slopes and forms horizontal terraces at different elevations.

The VCR exhibits highly erratic morphological and grade characteristics. Various footwall types underlie the orebody across the lease area.

in 2011, a project has been initiated to drill a series of holes from 112 level to explore the ground south of the Pretorius Fault Zone.

In December 2011, TauTona's mineral reserves were calculed at 6.34 million tonnes grading 9.40 g/t gold for 1.92 millon ounces gold. The reserves at the mine also contain an estimated 3.94 million pounds uranium.

Mining & Operation

TauTona mines the VCR and CLR, both narrow-vein tabular orebodies. The mine is predominantly a longwall operation, with the sequential grid mining method only contributing around 13% of output. TauTona has a main, sub-, and tertiary vertical shaft system, with just over 60% of production coming from the tertiary shaft area on the Lower CLR horizon. Mining takes place between 2,000 m and 3,640 m below surface. TauTona has the world's deepest stoping section, at 3,500 m. 

TauTona has payable ore reserves above 120 Level to 2011. This includes shaft pillar extraction of the CLR up to the zone of influence. The resource below 120 Level could be extracted via decline if economically viable.

The CLR shaft pillar project allows for stoping operations up to the infrastructural zone of influence. The project, from which production commenced in 2004, is expected to produce 550,000 ounces of gold over a period of 10 years, at a capital cost of $35 million (converted at closing 2004 exchange rate). The CLR reserve block below 120 level, known as TauTona below 120 level Project, is being accessed via a twin decline system into its geographical centre, down to 125 level. The project is expected to produce 2 million ounces of gold over a period of nine years.

Production on the VCR at TauTona ceased in 2011, but some isolated blocks that are above cut-off may still be mined in 2012. In that respect, the VCR Development Project aims to access two distinct reserve blocks on the VCR horizon, one situated north-east of the shaft complex, and the other in the VCR pillar area situated outside the zone of influence. The project will add some 300,000 ounces to production.

Processing

TauTona and Savuka mines share a common processing plant. This facility uses a conventional milling and carbon-in-pulp (CIP) process. Gold is loaded on to carbon at the plant and is then transported to the nearby Mponeng plant for electro-winning, smelting and final recovery.

Environment & Community

Safety

In 2011, there were no fatalities recorded at the mine but two fatalities occurred at TauTona during 2010 resulting from accidents related to winches and horizontal transport.

Community

TauTona plays an active role in supporting various community projects in the Merofong district. AngloGoldAshantimade donations to local organisations during the year.

Environment

An ISO 14001 first advancement assessment audit was conducted at TauTona in September 2010, with the operation retaining its accreditation.

No reportable environmental incidents were recorded during the year.