*School of Mining Engineering (ETDs)
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Item Optimisation of fragmentation at south deep gold fields mine: a case study(2020) Nong, MatsobaneA fundamental aspect of an efficient mining operation is the steady movement of material throughout the mine system; particularly the flow of ore from the upstream excavation point to the downstream processing or stockpile site(s). This can be achieved by attaining an optimal fragmentation size from drilling and blasting suitable for subsequent mining process such as loading, hauling and crushing. Drilling and blasting are the first fragmentation process and is currently the most economical technique of fragmenting hard and competent rock especially for deep-level mines where operational costs are high. The aim of this research is to analyse and optimise fragmentation to improve the oreflow efficiency at South Deep Mine in South Africa. The mine experiences coarse fragmentation that cannot pass through 300mm by 300mm grizzlies. As such, secondary blasting is often done to reduce the size of boulders either in the stopes or on top of the grizzly which leads to a reduction in productivity. Although coarse fragmentation is reported in the stopes and on top of grizzlies, the plant is reporting fine fragmentation that is not suitable for the ball mill. This results in reduced gold recoveries. To get a better understanding of the fragmentation size distribution achieved, fifty-one images of the muckpile from five stopes were analysed using the Split-Desktop software. The analysis showed an overall F80 passing of 287.48mm, which is less than the 300mm grizzly size implying that the fragmentation size achieved is adequate. However, looking at the overall particle size, the Rosin-Rammler distribution was found to be 0.80. This infers an inconsistent fragmentation where the mine produces both coarse and fine fragmentation size. The AEGIS Underground drill and blast software was used to analyse the drill and blast design patterns. The analysis showed that the design toe spacing varies from about 0.5m to 7.5m in the same blast. Due to the software’s limitations, the break model analysis was only run for toe spacing between 2m and 7.5m. This showed that there is no overlap between blastholes which may be the source of the coarse fragmentation size. Fine fragment size may be as a result of blastholes which are close together, i.e. 0.5m. Although not tested, the impact of blasting stresses emanating from primary stopes may result in fractures in secondary stopes which will have a greater impact on the propagation of the shock wave and high-pressure gases between the blastholes and consequently the fragmentation distribution size. It is recommended that the mine change their drill and blast pattern. The mine must change from 76mm blasthole diameters and introduce a larger blasthole diameter of 89mm blasthole diameter. Not only will this diameter improve drilling accuracies but will reduce the fragmentation size distribution. It is also recommended that the mine maintains a ring burden of 2m throughout despite an increase in the blasthole diameter. For the first design, the toe spacing must also be 2m followed by increments of 0.5m per blast until a suitable fragmentation distribution size is achieved. After which, the toe spacing must be kept constant. It is important that South Deep Mine continually evaluate the fragmentation size distribution achieved from each blast for optimisation purposes. Therefore, a blast management system is important.Item A comparison of various modelling techniques to optimise production rate on a platinum mining project(2021) Dreyer, JacoEvery business aims to create an optimal economic value for its shareholders. The production rate is one of the critical drivers of value in the mining business. Several approaches have been developed to determine the production rate for mining operations. This study applied three approaches for determining production rate, namely the tonnage-based, microeconomic and marginal-analysis modelling methods. These methods were applied on a platinum project, and the production rate results from the three methods were used to determine the life of mine (LOM) production profiles, capital expenditure (CAPEX) and operational expenditure (OPEX). These results were then used as inputs into a discounted cash flow (DCF) model. The DCF model results were compared and analysed to determine a production rate determination method that results in an optimum production output rate for the project. The study revealed that the tonnage-based modelling technique resulted in the highest production rate of 410-kilo tonnes per month (ktpm), the highest CAPEX of USD957.24 million, the lowest OPEX of USD75.37 per mined tonne, the highest net present value (NPV) of USD63.12 million and the highest internal rate of return (IRR) of 12.85% over a 40-year LOM. The microeconomic modelling technique ranked second with a production rate of 270 ktpm, CAPEX of USD 726.24 million, OPEX of USD 76.68 per mined tonne, NPV of USD 3.46 million and IRR of 10.17%. The marginal-analysis modelling technique ranked last with a production rate of 230 ktpm, CAPEX of USD 658.76 million, OPEX of USD 77.83 per mined tonne, NPV of USD -10.69 million and the lowest IRR of 9.47%. Mineral Resource tonnage-based modelling may be further investigated in other commodities other than platinum or other multi-element/polymetallic mineral deposits in line with the South African mining industry. This will result in the formulation of industry-specific calibration in the South African mining industryItem The underrepresentation of technical women in executive and board of directors’ roles in the ten largest listed mining companies in South Africa(2022) Zulu, NoluthandoAs with many technical industries, mining is dominated by men. It is well established that the industry has struggled with the attraction and retention of female talent. While women have made significant inroads in the industry, technical women (defined here as women who come from a geology, engineering, metallurgical, etc background) are underrepresented in the most senior decision-making roles of major mining companies. The purpose of the study was to explore this phenomenon, examining the executive committee and board composition of the 10 largest mining companies listed on the Johannesburg Stock Exchange and interviewing 30 technical women who have worked for, or currently work for, these organisations. The results demonstrate that technical women seldom advance from operations to the boardroom and, typically, play a support function while men make core mining and technical decisions. The study also finds that many technical women move into nontechnical roles for a number of reasons. Further, while attraction of women to the industry continues to rise, the studied companies are struggling to retain technical female talent. The study further highlights the significance of government intervention concerning the inclusion and advancement of women in mining. It also emphasises the need for continued policy development and concludes with recommendations on how mining companies can drive both the inclusion of women in mining as well as their corporate advancement.Item Improving open pit mine economics through ultimate pit slope optimization: case study of Pickstone-Peerless mine(2024) Nyamande, PardonIn most open pit mining operations the need to create stable pit slopes and the influence of the overall pit slope on the economics of such an operation is highly appreciated. Despite such knowledge many open pit mines are designed with little or no geotechnical investigations being carried out so as to come up with an optimized pit slope in line with site specific conditions. This can lead to under or over estimating pit slope angles. Conservative (too gentle) slopes result in high stripping ratios therefore a high operating cost. Slopes too steep may result in slope failures, which may lead to high operating costs or premature mine closure. This project emphasises the importance of geotechnical investigations not only for safety reasons but for economic reasons as well. A case study of Pickstone Peerless mine was used. Geotechnical data was gathered through core logging and face mapping of the existing pit. The data gathered was then used for stability analysis employing empirical, kinematics, limit equilibrium and numerical modelling. Rocscience software packages were used for numerical based analysis. From the results obtained it was concluded that it is possible to steepen the current 52o overall pit slope angle of the Peerless pit by 1o without compromising stability at both bench and regional scales. This will be possible provided adequate slope management practices are put in place and adhered to. The steeper slope would have saved the mine more than 2,681,110 m3 of waste stripping, translating to in excess of $12,064,995.00 (USD) in financial savings for the existing pit. The steeper angle applicable to the current pit may not be appropriate to the pit extensions. Further geotechnical evaluations should be done on suitably positioned and spaced boreholes in the area of the extension, to verify the stability of steeper slopes in that area. The analysis done as part of this project was used to show that the current pit can be deepened by 5 m without a push back.Item The incorporation of unmanned aerial vehicles in a slope stability monitoring system: a Rössing uranium mine case study(2024) Shanyengana, Olga NdapewoshaliSlope stability monitoring is a safety critical input in the Slope and Dump Management Plan (SDMP) at Rössing Uranium Limited (RUL) mine. The SDMP was adopted to satisfy the requirements of the D3 standard – management of slope geotechnical hazard at the operation. Through this standard, RUL aims to provide an injury-free and safe working environment for the operation. This is achieved by proactive identification and management of slope risks and instabilities onsite. This research is a case study of the incorporation of unmanned aerial vehicle (UAV) technology into the slope stability monitoring system (SSM) at RUL, towards conformance to the D3 standard. The study highlights the safety benefits gained by removing personnel from hazardous areas and substituting them with UAVs. The utilisation of UAV data in geotechnical processes such as; the final wall assessment, crack detection and monitoring, as well as dump advancement rate calculations are also discussed. The study further investigated the use of UAVs for SSM prism inspections and proposes the incorporation of UAVs into the trigger action response plan (TARP). A concept of UAV modification for prism-cleaning operations has been developed through this research, to alleviate the challenges of prism loss in inaccessible areas due to dust accumulation on the prism surfaces.Item Application of derivative techniques to improve the forecasting of price volatility of copper, gold and platinum metals(2024) Veriyadi, VeriyadiThis research investigates the forecasted price volatility of copper, gold and platinum metals based on the selected companies; Palabora Copper Mining Ltd, AngloGold Ashanti Ltd, Gold Fields Ltd, Sibanye-Stillwater, Anglo Platinum Ltd and Impala Platinum Ltd. In responding to the latter sentence, single price volatilities are dual volatilities, where dual volatilities comprise of financial and technical variables. The selected firms either have global operations or they are subsidiaries of global companies. Dual volatility is computed using a Sample Correlation Coefficient and in order to explore the dual volatility, this research introduces three hypotheses. The first hypothesis uses a Decision Tree Analysis to test dual volatility based on financial and technical variables (e.g., mineral commodity price, metal grade, operating cost and production rate) in improving the forecasting of price volatility of copper, gold and platinum metals. For validation, the first hypothesis uses the Markov-Regime Switching Model. The results of this hypothesis illustrate that dual volatilities are more accurate and robust than price only volatilities. Then, the second hypothesis examines dual volatility using a GBM model. This hypothesis tests dual volatility; which is computed based on financial and technical variables (e.g., oil price, copper price, oil production and consumption, copper production and consumption; and the exchange rate from U.S.$ to ZAR and gold and platinum price data). The chosen variables that affect the dual volatility are examined using a Multiple Regression Model and that model confirms that those variables are independent in principle. Finally, the third hypothesis estimates future profits based on a binomial tree, which has risk-neutral probabilities based on dual volatility using mineral commodity price, metal grade, operating cost and production rate. The results of risk-neutral probabilities using dual volatility are less optimal than a mineral commodity price volatility due to not accounting for the mean of logarithmic returns. The robustness test uses the VAR model, which indicates that the profits react differently to different shock stages from revenues, risk-free interest rates and profits. In conclusion, dual volatility can improve future price forecasting performance because duality is underpinned by different variables, which include independent variables from the global commodity markets. The forecasting performance improvement from dual volatility in predicting the future price can be shown by the lower value of the Root Mean Square Error and Mean Absolute Percentage Error results than a mineral commodity price volatility. The findings of this research apply to copper, gold and platinum metals for mining around the globe.Item Analysis of the developmental potential of artisanal and small-scale mining: a strategy for South Africa(2024) Twala, Pontsho FrancinahThe mining industry remains central to the socio-economic development of mineral economies. While this is the case, most African countries have been struggling to translate the benefits of mining into positive developmental outcomes. This has been attributed to several factors including the failure to leverage opportunities from the Artisanal and Small-Scale Mining (ASM) sector which has been growing in most countries. As is the case in other African countries, the mining industry continues to play a considerable role in South Africa’s economy. The industry is expected to contribute significantly to the country’s socio-economic agenda which aims to eradicate poverty and inequality by 2030. Despite the positive outlook, the performance of the industry has been declining resulting in the government identifying a series of interventions aimed at reviving the industry’s activities. Amongst these is the formalisation of the ASM which has been earmarked for job creation and poverty alleviation. The objectives of the Thesis were to establish the developmental potential of ASM in the country, and subsequently develop a strategy framework aimed at enabling the sector to contribute to the mining industry and national development plan. The study was conducted using multiple case studies with data collected and analysed using multiple methods. The major finding from the study is that the ASM sector has the potential to contribute towards the country’s development priorities. This is taken from the evidence that shows a direct link between the sector’s activities and the country’s socio-economic landscape. It was established that the main drivers of ASM are socio-economic challenges in the country, mainly growing unemployment and poverty levels. To this end, ASM is playing a role in providing livelihoods to country’s population is that most affected by poverty and unemployment. As a livelihood strategy, ASM has improved the poverty status as well as the living standards of those that participate in its activities. The evidence from the study revealed that most of the miners measure above the country’s subsistence level and can provide for themselves and their families. The benefits of the sector also extend to communities and overall, these can be linked to several objectives as captured in the country’s development plan. The conclusion from the study is that the developmental potential of ASM can only be leveraged if the challenges in the sector are addressed, and these encompass issues relating to the regulation of the sector, mining land and mineral resources; value chain constraints, and related support, responsible practices, institutional arrangements, and ASM stakeholder relationships.Item Utilising interferometric synthetic aperture radar and ground-based radar data to predict time to failure and to calibrate numerical models on an opencast coal mine(2024) Strydom, JacquesAccurate time failure predictions and improved geotechnical certainty in an opencast mine will lead to tremendous safety and economic benefits. This study utilises interferometric synthetic aperture radar and ground-based radar data to conduct a back analysis on slope failures that have occurred in an opencast coal mine in South Africa. Time to failure predictions was done utilising the inverse velocity technique, while the effect of different data smoothing techniques on the accuracy of the failure predictions was evaluated. Additionally, ground-based radar data was used to calibrate a finite element numerical model to improve geotechnical certainty. Time to failure predictions based on satellite monitoring data was less accurate than predicted in the literature, but satisfactory results were obtained from ground-based radar data. This study confirms that displacement measurement from ground-based radars may be used to optimise the strength parameters of finite element numerical models. To improve the accuracy of time to failure predictions from satellite monitoring data, it was proposed that a satellite constellation with a shorter data acquisition time must be utilised. By having access to more frequent data acquisitions and by identifying the most active points within the failure zone of a slope, it is expected that the accuracy of the time to failure predictions can be improved.Item Geometallurgical influence of clays on the Jwaneng kimberlite value chain(2024) Nkgakile, NaomiGeometallurgy is a cross- disciplinary function that provides a better understanding of the ore characteristics impacting the treatability of the material. Optimal treatment of the material is enabled by understanding variability in the ore body. Having this understanding leads to flexibility when planning mining mixes. The present investigation of the Jwaneng DK2 deposit’s geometallurgical responses demonstrate that various rock lithologies impact the treatability of the Jwaneng kimberlites. The plan t is therefore hindered from achieving design capacity as a result of its treatability constraints. The volcaniclastic kimberlite, which is a majority- treated lithology at Jwaneng Mine, contains the highest volumes of smectite clays. These clays cause settling challenges resulting in higher consumption of processing materials. To allow for informed strategic planning, all vital treatability information on the clayrich kimberlites needs to be collected. The clay occurrence can then be incorporated into the creation of the geometallurgy model. Then the completed geometallurgical model can be utilised as a predictive tool for planning