Name: Mponeng mine.

Location: The Mponeng mine, which was formerly named Western Deep Levels South, is situated south of the combined TauTona and Savuka mines, near the town of Carletonville and about 65 km west of Johannesburg, in South Africa’s Gauteng province.

Controlling Company: AngloGold Ashanti.

Brief History: Mponeng’s original twin shaft sinking from surface started in 1981 and was commissioned along with the gold plant complex in 1986 when production began.

Brief Description: Mponeng forms part of AngolGold’s West Wits operations, which includes the TauTona and Savuka mines. It is the world’s deepest gold mine and AngloGold’s flagship operation in the South African region. The mine exploits the Ventersdorp Contact Reef (VCR) at depths of between 2 400 m and 3 900 m using a twin-shaft system.

Geology/Mineralisation: The VCR is the main reef horizon mined at Mponeng. The VCR forms the base of the Ventersdorp supergroup, which caps the Witwatersrand Supergroup through an angular unconformity. The overlying Ventersdorp Lavas halted the deposition of the VCR, preserving it in its current state. The VCR consists of a quartz pebble conglomerate, which can be up to 3 m thick in places. The footwall stratigraphy, following a period of uplift and erosion, controlled the development and preservation of the VCR. The footwall comprises a series of sedimentary layers from the Central Rand Group of the Witwatersrand Supergroup that, owing to its erosional nature, exposes the VCR from the youngest layers in the west to the oldest in the east.

The other gold-bearing reef with a reported mineral resource for Mponeng is the Carbon Leader reef (CLR). This reef has been mined at the adjacent Savuka and TauTona mines, and plans are being made at Mponeng to mine the CLR in the future. The CLR at Mponeng consists of a 20-cm-thick, tabular, auriferous quartz pebble conglomerate formed near the base of the Central Rand Group. The CLR is about 900 m deeper than the VCR. In recent years, extensive work has been done in refining the estimation model for CLR. This has resulted in a decrease in value of the mineral resource and an improved confidence in the estimation.

The VCR and the CLR have been subjected to faulting and are intruded by a series of igneous dykes and sills of various ages that cross-cut the reefs. There is an inherent risk in mining through these faults and intrusives and a key objective of AngloGold Ashanti mine geologists is to identify these geological features ahead of the working face to assist in deciding on best practice when approaching or mining through these structures.

Reserves: Total mineral reserves as at December 31, 2014, were 42.1-million tonnes grading 9.55 g/t of gold.

Resources: Total inclusive mineral resources as at December 31, 2014, were 86.38-million tonnes grading 17.52 g/t of gold. Total exclusive mineral resources were 44.12-million tonnes grading 18.01 g/t of gold.

Products: Gold.

Mining Method: Underground.

Major Infrastructure and Equipment: Using two hoisting shafts, a subshaft and two service shafts, Mponeng exploits the VCR between depths of 2 800 m and 3 400 m below surface.

Ore is treated and smelted at the mine’s gold plant.

Prospects: South of the Mponeng lease area lies the Western ultradeep levels area. This area is being explored through a surface drilling programme and from underground drilling platforms.

Contact Person: Stewart Bailey.
Contact Details:
AngloGold Ashanti,
tel +27 11 637 6031,
email sbailey@anglogoldashanti.com, and
website http://www.anglogoldashanti.com.