Mponeng is situated on the northwestern margin of the Witwatersrand Basin of South Africa, one of the prominent gold provinces in the world. There are seven gold-bearing conglomerates within the lease area, of which only the Ventersdorp Contact Reef (VCR) and Carbon Leader Reef (CLR) are economically viable. The Ventersdorp Contact Reef (VCR) is the main reef horizon mined at Mponeng Mine. 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 Carbon Leader Reef (CLR), previously mined at Tau Tona and Savuka mines, is found within the Witwatersrand Supergroup. The CLR lies 900m beneath the VCR on Mponeng. The VCR is preserved across the Mponeng lease area and dips at approximately 22 degrees in a SSE direction. The VCR was deposited on uneven footwall strata due to uplift and is now represented by a shallow angular unconformity. The footwall lithologies to the VCR therefore vary across Mponeng Mine as the unconformity cuts deeper in an easterly direction into older strata of the Witwatersrand Supergroup. Fluvial action during deposition of the VCR continually eroded and reworked the conglomerate, creating steep slopes and embayment’s between relatively undisturbed terraces. The CLR conglomerate was deposited by several sedimentary cycles. Erosion and reworking of the conglomerate and quartzite sed ........

Mponeng is a deep level underground gold mine currently operating at depths ranging between 3,160m and 3,740m BMD, and currently the deepest mine in the world with development at 3,841m BMD. Potential future mining operations at Mponeng are expected to deepen the shaft bottom to 4,227m BMD. The reef portion currently being mined at Mponeng is accessible between 3,000 – 3,600m BMD.

There are two mining methods in practice at Mponeng. While Mponeng’s business plan is based primarily on the SGM method, there are sections of the mine that are still operating using the breast mining method. The mining sequence is a V-shaped configuration, colloquially referred to as the “inverted Christmas tree”. An underhand face configuration is adopted when mining towards the west and an overhand face configuration when mining towards the east.

The orebody is extracted mostly by breast-mining methods with associated waste mining in addition to the reef being extracted. The dilution from these waste sources is captured and incorporated in the tonnage calculation, with historical performance being the benchmark. The mine exploits the Ventersdorp Contact Reef as its primary orebody. The economic reef horizons are mined between 3 160m and 3 740m below surface.

In addition to the in-stope dilution sources being accounted for allowance is also made for dilution from development waste sources to mill by both schedule results and factors based on history. Widths used a ........

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