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AngloGold Ashanti Surface Operations, South Africa

15th July 2016

By: Sheila Barradas

Creamer Media Research Coordinator & Senior Deputy Editor

  

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Name: AngloGold Ashanti Surface Operations.

Brief Description: AngloGold Ashanti Surface Operations in South Africa produce gold by processing surface material such as low-grade stockpiles and through the retreatment of tailings storage facilities (TSFs). Surface operations comprise the Vaal River (VR) surface, West Wits surface and the Mine Waste Solutions (MWS) processing operations.

Location: The VR surface operations are located to the north and south of the Vaal river, close to the town of Orkney, in South Africa’s North West province. The MWS operation is located about 8 km from Klerksdorp, near Stilfontein, within 20 km of the VR surface operations. The West Wits surface operations are located on the West Wits line, near Carletonville, across the border between the North West and Gauteng provinces.

Controlling Company: AngloGold Ashanti.

Brief History: Gold from surface material has been produced routinely since 2002. AngloGold Ashanti acquired the MWS tailings retreatment operation in the Vaal river region in July 2012. The MWS uranium plant and flotation plants were commissioned in 2014.

Products: Gold and uranium by-products.

Geology/Mineralisation: The material contained in the TSF and low-grade stockpiles originates from the historic ore-bearing reefs mined at the West Wits, the VR, Buffelsfontein, Hartebeestfontein and Stilfontein gold mines. The material contained in the TSFs is fine grained.

Gold contained in the lower-grade stockpiles is from minor reefs that are intersected, while accessing the primary gold- bearing reef that is contained within small fault blocks that are exposed by off-reef development and cross-tramming of gold- bearing reef material to the waste tips.

The tailings dams comprise tailings material from the processing of the underground ore from the VR operations, the West Wits operations, Buffels, Hartebeestfontein and Stilfontein gold mines. These gold mines are deep-level mines, which predominantly extract the tabular, conglomeratic VR, Carbon Leader reef (CLR) and Ventersdorp Contact reef (VCR). The VR has been predominantly mined for gold in the past, although the reef also contains uranium oxide, the same is true, but to a lesser extent, for the CLR and VCR.

The material contained in the tailings dams is fine in nature. The footprints of the MWS tailings dams and the VR surface operations tailings dams cover about 1 100 ha.

Reserves: Proven and probable reserves as at December 31, 2015, were estimated at 757.64-million tonnes, grading 0.26 g/t of gold.
Resources: Exclusive mineral resources from the VR, West Wits surface operations and MWS as at December 31, 2015, were estimated at 209.63-million tonnes, grading 0.33 g/t of gold.
Mining Method: For low-grade stockpiles, bulldozers are used to create furrows through the stockpile to blend the rock and create safe loading faces. The material is then loaded onto rail hoppers or trucks using a front-end loader and transported to the relevant gold plants for processing.

The tailings from the TSFs are reclaimed using several hydraulic monitoring guns to deliver water at pressure, typically 27 bar to 30 bar, to the face. The tailings material is reclaimed by blasting the TSF face with the high-pressure water, resulting in the slurry gravitating towards the pumping stations. These monitoring guns can be positioned to selectively reclaim required areas from the TSFs. Bench heights are constrained by the force delivered from the monitoring gun nozzle and safety constraints. With sufficient pressure, face lengths of up to 25 m can be reclaimed.

The reclamation strategy aims to process the higher-grade dams first. The pumpstations are located at the lowest point of the dams to ensure that the slurry from the dams will gravitate towards the pumpstation from where the slurry will be pumped to the processing plants.

Major Infrastructure and Equipment: Mineral process depends on the source material. Tailings material is pumped directly to a conventional carbon-in-leach plant, while hard rock material will undergo comminution first.

Sulphur separation takes place where required and, in the case of the MWS operation, uranium is extracted using acid leach. The MWS comprises the Stream 1, 2 and 3 gold plants. Hydraulically reclaimed material from several TSFs is delivered to the three plants for gold extraction.

The West Wits surface operations process low-grade stockpile material sourced from the mining of the CLR and the VCR that are mined by the West Wits mines in the Carletonville/Fochville area.

Within the Vaal river area, the Kopanang, West and Mispah gold plants are dedicated surface operations plants. In the West Wits area, the Savuka plant processes surface material.

Prospects: The construction of a new pumpstation for connecting the VR East TSF to the MWS circuit was completed in 2015. Successful commissioning of the pumpstation was concluded in mid-2015. The commissioning of the East pumpstation increased the flexibility and reclamation capacity for the MWS operation.

Contact Person: Senior VP investor relations and group com- munications – global, Stewart Bailey.

Contact Details:
AngloGold Ashanti,
tel + 27 11 637 6000,
email sbailey@anglogoldashanti.com, and
website http://www.anglogoldashanti.com.

Edited by Tracy Hancock
Creamer Media Contributing Editor

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