ETD Collection

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    Economic viability of K04 open pit mineral resource to ameliorate production hiatus in 2019 and 2022
    (2019) Mushongahande, Emmanuel
    Venetia Mine is the largest diamond mine for the De Beers Group of Companies (DBGC) in South Africa contributing approximately 80% of revenue for the company. The Venetia Kimberlite Cluster (VKC) comprises of 13 pipes and one dyke, of these K01, K02, and K03 are mined productively while the satellite bodies that are intersected during waste stripping and push backs are stockpiled separately. The current open pit operation will come to an end in 2022, whereupon the K01 and K02 ore bodies will be mined from underground. Shaft sinking and development of underground infrastructure is underway, and it is envisaged that the change over from open pit to underground will be effected in 2022. There are two challenges facing the company that may result in a production hiatus in 2019 and 2022. The first challenge relates to failure to open kimberlite ore in the Cut4 south push back by 2019 and the second one is failure to seamlessly change from open pit to underground in 2022 when the open pit reaches its Life of Mine (LoM). The backlog of waste stripping in the Cut4 south and technical challenges faced in the implementation and execution of the Canadian Shaft Sinking method at Venetia Mine have both pointed to periods where there will be less ore mined thus resulting in less carats recovered. In order to cushion for these scenarios, the economic viability of K04 satellite pipe was investigated by conducting a Whittle optimum pit selection of the pipe to mine the ore. This was previously excluded by the current pit design. The strategy for K04 optimum pit selection was based on net present value (NPV), revenue factors, stripping ratios, and the life of the mine. This strategy was employed when analysing 13 pits from scenario 2. The selection process identified pit 9 as an optimum pit. It must be noted that this pit inventory does not add significant numbers of carats to the overall carat profile to lift the valley of despair in 2019 and 2022 but will contribute some NPV of ZAR13.2 million over a period of 6 years. K04 project will contribute 402 thousand carats against 1.5 million carats required to fill the hiatus gap, hence does not support a sound business case for Venetia Mine. It is therefore recommended that DBCM deploy a different strategy to reduce the impact of the carat shortfall in 2019 and 2022. Some recommendations include reducing mining activities in the north of the pit and focus more on accelerating waste stripping in the south in order to expose ore sooner. Cost saving initiatives such as reducing operating costs and postponing some capital projects that are deemed not urgent will go a long way in the reducing the financial impact in 2019 and 2022.
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    An evaluation of chromitiferous layers and their host rocks in the Platreef, on the Turfspruit and Zwartfontein properties: a comparative study with the main Bushveld Complex
    (2017) Cronje, Louwrens
    The origin of the Platreef in the northern limb of the Bushveld Igneous Complex remains a topic of debate. Its relationship with that of the PGE-reefs of the Main Bushveld Complex is disputed and there is currently no widely accepted theory available, as both parties have valid arguments. This study involves the stratigraphic, petrographic and chemical investigation of the chromitiferous layers and their hosts, in the Platreef, on both the Turfspruit and Zwartfontein properties. The work in this study has shown that the conventional stratigraphy that defines the upper Critical Zone is not present in the study areas, which lack the sophisticated layering and cycles present in the main complex and generally, rocks are significantly more heterogenous in the Platreef than elsewhere in the Bushveld Complex. A large number of petrographic similarities were identified in the study area, when compared to known textures and morphologies published by previous workers, especially on the Upper Group chromitite layers. The chemistry of the Platreef reflect a more primitive magma responsible for the deposition of these rocks, which is demonstrated through higher Mg contents, and lower Ti, indicating less fractionation when compared to the main Bushveld Complex. It must be stated that the influence of contamination on Mg-rich lithologies may have altered their composition, which could have generated misleading results. Statistically, the results obtained may not be entirely representative of the true chemical character of the entire northern limb, and the opinions and assumptions made are very localised. This study concludes that the upper Critical Zone magma was probably not responsible for the deposition of the Platreef, while rocks were locally altered due to contamination from country rock.
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    The felsic intrusives In E.R.P.M., Boksburg
    (2015-03-16) Fumerton, Stewart Lloyd; ;