Faculty of Engineering and the Built Environment (ETDs)

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A Data Science Framework for Mineral Resource Exploration and Estimation Using Remote Sensing and Machine Learning
(University of the Witwatersrand, Johannesburg, 2023-08) Muhammad Ahsan, Mahboob; Celik, Turgay; Genc, Bekir
Exploring mineral resources and transforming them into ore reserves is imperative for sustainable economic growth, particularly in low income developing economy countries. Limited exploration budgets, inaccessible areas, and long data processing times necessitate the use of advanced multidisciplinary technologies for minerals exploration and resource estimation. The conventional methods used for mineral resources exploration require expertise, understanding and knowledge of the spatial statistics, resource modelling, geology, mining engineering and clean validated data to build accurate estimations. In the past few years, data science has become increasingly important in the field of minerals exploration and estimation. This study is a step forward in this field of data science and its integration with minerals exploration and estimation. The research has been conducted to develop a state-of-the-art data science framework that can effectively use limited field data with remotely sensed satellite data for efficient mineral exploration and estimation, which was validated through case studies. Satellite remote sensing has emerged as a powerful modern technology for mineral resources exploration and estimation. This technology has been used to map and identify minerals, geological features, and lithology. Using digital image processing techniques (band ratios, spectral band combinations, spectral angle mapper and principal component analysis), the hydrothermal alteration of potential mineralization was mapped and analysed. Advanced machine learning and geostatistical models have been used to evaluate and predict the mineralization using field based geochemical samples, drillholes samples, and multispectral satellite remote sensing based hydrothermal alteration information. Several machine learning models were applied including the Convolutional Neural Networks (CNN), Random Forest (RF), Support Vector Machine (SVM), Support Vector Regression (SVR), Generalized Linear Model (GLM), and Decision Tree (DT). The geostatistical models used include the Inverse Distance Weighting (IDW) and Kriging with different semivariogram models. IDW was used to interpolate data points to make a prediction on mineralization, while Kriging used the spatial autocorrelation to make predictions. In order to assess the performance of machine learning and geostatistical models, a variety of predictive accuracy metrics such as confusion matrix, a receiver operating characteristic (ROC) curve, and a success-rate curve were used. In addition, Mean Absolute Error, Mean Square Error, and root mean square prediction error were also used. The results obtained based on the 10 m spatial resolution show that Zn is best predicted with RF with significant R2 values of 0.74 (p < 0.01) and 0.7 (p < 0.01) during training and testing. However, for Pb, the best prediction is made by SVR with significant R2 values of 0.72 (p < 0.01) and 0.64 (p < 0.01) for training and testing, respectively. Overall, the performance of SVR and RF outperforms the other machine learning models with the highest testing R2 values. The experimental results also showed that there is no single method that can be used independently to predict the spatial distribution of geochemical elements in streams. Instead, a combinatory approach of IDW and kriging is advised to generate more accurate predictions. For the case study of copper prediction, the results showed that the RF model exhibited the highest predictive accuracy, consistency and interpretability among the three ML models evaluated in this study. RF model also achieved the highest predictive efficiency in capturing known copper (Cu) deposits within a small prospective area. In comparison to the SVM and CNN models, the RF model outperformed them in terms of predictive accuracy and interpretability. The evaluation results have showed that the data science framework is able to deliver highly accurate results in minerals exploration and estimation. The results of the research were published through several peer reviewed journal and conference articles. The innovative aspect of the research is the use of machine learning models to both satellite remote sensing and field data, which allows for the identification of highly prospective mineral deposits. The framework developed in this study is cost-effective and time-saving and can be applied to inaccessible and/or new areas with limited ground-based knowledge to obtain reliable and up- to-date mineral information.
Analysis of the developmental potential of artisanal and small-scale mining: a strategy for South Africa
(2024) Twala, Pontsho Francinah
The 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.
Application of derivative techniques to improve the forecasting of price volatility of copper, gold and platinum metals
(2024) Veriyadi, Veriyadi
This 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.
Benefits of using Internet of Things technology for fuel management at a mechanised underground platinum bord and pillar mine: A Bathopele mine case study
(University of the Witwatersrand, Johannesburg, 2024-01) Thema, Sephela Makete; Cawood, Frederick; Feroze, Tariq
The advent of the fourth industrial revolution, Environmental Social and Governance (ESG), and push for green energy transition has propelled mining companies to reconsider their strategies. Over the past two decades, mining companies along the Bushveld Igneous complex in South Africa have been shifting towards mechanized mining methods which are generally safer and provide for the generation of greater volumes of output. Sibanye Stillwater’s Bathopele mine, which has a fleet of over two hundred and fifty (250) trackless mobile machinery (TMM) and a daily fuel consumption of approximately ten thousand (10 000) liters per day. The introduction of Internet of Things (IOT) technology in the fuel management system at Bathopele mine achieved benefits such as fuel consumption tracking, effective inventory management, prevention of fuel theft, detection of fuel leaks, determination of maintenance requirements and readily available access to fuel use data. This access to data enabled the mine to effectively apply for fuel use rebates from the South African Revenue Services (SARS) with ease. To determine the impact of the increased distance to underground working places on the refueling of TMM, the Theory of Constraints (TOC) method, qualitative and quantitative techniques were applied. A bivariate analysis conducted indicated a linear relationship between fuel consumption and production output at Bathopele mine, which suggests that an effective fuel management system had a positive impact on production output at the mine. A real-time or near real time model for fuel management in underground trackless bord and pillar mines in proposed.
A comparison of various modelling techniques to optimise production rate on a platinum mining project
(2021) Dreyer, Jaco
Every 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 industry
Geometallurgical influence of clays on the Jwaneng kimberlite value chain
(2024) Nkgakile, Naomi
Geometallurgy 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
Improving open pit mine economics through ultimate pit slope optimization: case study of Pickstone-Peerless mine
(2024) Nyamande, Pardon
In 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.
Optimisation of fragmentation at south deep gold fields mine: a case study
(2020) Nong, Matsobane
A 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.
Pegmatite investigations in the Karibib district, South West Africa
(University of the Witwatersrand, Johannesburg, 1963) Roering, Christian
The outer pegmatitie zone of variable thickness which is essentially a very coarse-grained granite consisting of larger perthite phenocrysts lying in a matrix of albite, quartz and muscovite. The inner portions of this zone may reveal a great enrichment of perthite, so much so, that it may grade into a giant perthite zone, e. g. Rubicon main ore-body; Karlsbrunn close to the Li-bearing ore zones. This outer portion of the pegmatite may also reveal a subdivision into two distinct units: an outermost zone of albite-quartz-muscovite and an inner zone of albite-perthite-quartz-muscovite. This sequence of essentially granitic crystallization is often abruptly broken by the appearance of a zone consisting essentially of cleavelandite with minor quartz and muscovite. This zone is characterized by the appearance of numerous accessory minerals often in economic quantities, e. g. beryl, columbite-tantalite-frondellite, topaz and apatite. The zone is generally of the order 1-5 feet depending on the original size of the pegmatitie and the degree of fractionation. That it is not a late replacement unit is confirmed by observations at Rubicon where corroded crystals of beryl belonging to this zone are found lying in a matrix of lepidolite and albite which is the next unit to form. The lepidolite-albite zone in fact replaces the beryl-bearing zone. The striking symmetry alone of the Rubicon body testifies to this zone preceeding in crystallization sequence the Li-ore zones. The significant fact about this zone is that it marks a distinct break in the crystallization history of the pegmatite, i. e. it marks the change from crystallization of essentially granitic components to the formation of late phase constituents, viz. Li-bearing and associated minerals. It possibly marks the break from magmatic crystallization to late-magmatic conditions when pneumatogenic and even hydrothermal processes begin to operate. The next group of minerals to form are noticeably rich in Li and are frequently associated with sugary albite. The major minerals are petalite, lepidolite and albite, while minor amounts of amblygonite also occur. There is a definite spacial relationship sequence in the formation of these minerals. Petalite crystallizes first and collects in the upper part of this unit generally forming a hood. Amblygonite, albite, quartz, may occur at the same time. Immediately below this petalite hood, and at a somewhat later stage, fine-grained lepidolite crystallizes together with albite and minor quartz. The final phase to form at this general stage is sugary albite which collects at the bottom of the still non-crystalline portion of the magma chamber. The sugary albite phase is able to behave diapirically and can intrude, brecciate, and replace any of the previously crystallized zonal constituents. Each successive stage here can assume corrosive relationships to previously consolidated units. No assessment is made as to the amount of replacement that may take place as the criterion commonly used for such diagnosis are somewhat subjective. During this entire process of complex diffusions and crystallization, silica is apparently being concentrated in the residual fractions of the pegmatite magma. The next zone to form is a cleavelandite-rich rock confined to the quartz core margin. This cleavelandite is able to vein and brecciate and corrode the immediately adjacent lying lepidolite and is often associated with minerals such as beryl, columbite, tantalite, tourmaline, topaz and apatitie. Amblygonite may also belong to this stage of mineralization though in general it tends to be associated close in time with the petalite stage of mineralization. The final stage of the crystallization sequence is the quartz core. Quartz veinlets emanating from the core have been observed to cut across adjacent lepidllite-rich and amblygonite-albite zones. Euhedral crystals of columbite and beryl at the core margin are completely surrounded by quartz. These observations may suggest that quartz, although concentrated in the centre of the dyke, probably existed in some unconsolidated state (e. g. a gel as Brotzen (1959) has suggested). The development of a gas phase at certain stages of the pegmatites consolidation history possibly accounts for the vertical fractionation found in these pegmatites. Finally details of the more important pegmatite minerals are given together with chemical analyses.
Pit Optimisation of Vondeling Quarry by Understanding Geotechnical Parameters Determined at Zoutkloof Quarry
(University of the Witwatersrand, Johannesburg, 2023-11) Mukwevho, Tshinanne Matty; Pillay, Ohveshlan
The purpose of the study was to investigate the geotechnical parameters at Zoutkloof quarry and how they affect stability and the mine planning process. The geological features of Zoutkloof and Vondeling are similar, hence the lessons learned while mining Zoutkloof quarry can be used when mining Vondeling quarry. Zoutkloof quarry has already reached its limits and is no longer operational. It is important that mine planning considers the critical geotechnical parameters. The main reason for this consideration is to keep slope walls stable, employees and equipment safe, and to continue mining the ore in an economical manner. The methodology of the research incorporated highlighting the literature in the public domain on geotechnical considerations in open pit mining. Evaluating geotechnical parameters such as groundwater, rock mass strength, slope angle and monitoring; and additionally, showed scheduling of mining blocks from 2007 to 2008 formed part of methodology in the research. The results analysis indicated that the strategies implemented to control groundwater were successful to keep the production benches dry and walls stable. Good understanding of the discontinuities and the rock mass strength enabled the quarry to be divided into ground control districts. Kinematics analysis for possible failures was done and the results showed that there was no probability of failure on planar mode. However, there were minor possibility that failure can occur on wedge and toppling mode. Yearly mining scheduling was completed, focusing on tonnage and quality requirements. During this period, Zoutkloof had minimum waste mined and the quarry had narrowed significantly which required the operational team to work within mine design specifications to maintain safety and slope angles. Some resources had to be compromised as it was not practical to exploit them safely. The research concluded its findings as successful because Zoutkloof quarry was mined completely with approximately 10 slope failures that resulted with no injuries to employees or damage to equipment. The factors of safety (FOS) were evaluated to be well above one and slopes remained stable until mining ceased. The research also made recommendations that can be implemented while the Pretoria Portland Cement (PPC) continue to mine Vondeling quarry to aid same success as Zoutkloof while being cost effective.
Selection of an Optimal Tunnel Development Method for an Underground Mine Travelling Way Using an Analytic Hierarchy Process
(University of the Witwatersrand, Johannesburg, 2024-01) Meyer, Berto; Musingwini, Cuthbert; Tholana, Tinashe; Sihesenkosi, Nhleko
This research study was conducted at the Marikana Operations (Marikana) which are situated within the Western Limb of the Bushveld Complex (BC) located in the North West province of South Africa. The Marikana Operations mine platinum group metals (PGM) using conventional underground mining methods. The Marikana Operations are owned by Sibanye-Stillwater. The PGM conventional underground mining entails extracting a shallow-dipping narrow reef horizon which is accessed via a network of development workings. Within this layout, a travelling way is an inclined tunnel that connects lateral development workings with the workings on the reef horizon. At Marikana the conventional hand-held mining method is used to excavate travelling ways. However, there was a trial process completed that proved the viability of the inverse drop raising method of excavating travelling ways at Marikana. With more than one viable tunnelling method being available for travelling way development, the need arose to select an optimal travelling way development method for Marikana. The selection is a multi-criteria decision making (MCDM) process because it requires the simultaneous consideration of several factors when evaluating the different alternatives or options. Commonly applied tunnelling techniques were reviewed leading to the selection of both the hand-held drill and blasting method and the inverse drop raising method as applicable to the conventional underground mining environment and specifically to travelling way development. Thereafter, Multi Criteria Decision Analysis (MCDA) techniques were reviewed, and the Analytic Hierarchy Process (AHP) was selected as the MCDA technique to be used as the selection tool for the research, due to its several advantages such as the ability to detect inconsistencies in judgements and provision to remedy the inconsistencies. After the application of AHP, the inverse drop raising method scored 7.2% higher than the hand-held method with a 53.6% versus 46.4% score. The inverse drop raising method was therefore selected as the optimal method to develop travelling ways at Marikana. With the approach that both these methods are currently being executed at Marikana, the inverse drop raising method is nearly twice as expensive as the conventional hand-held method. If PGM prices become a constraint, the method might not be sustainable if executed the way that it is done at the Marikana Operations from a cost perspective. It is suggested that further research should be done to see how the method can be executed more cost-effectively.
Slope Failure Prediction at Husab Open Pit Mine in Namibia
(University of the Witwatersrand, Johannesburg, 2023-12) Thikusho, Christine Runguro; Watson, Bryan P.
The study is focused on Domain D at Husab Mine in Namibia. The purpose of the study was to improve prediction of pending slope failures for planar and wedge configurations. Planar and wedge failures are similar in that little strain is required to initiate failure. Slope monitoring systems such as ground based radars, interferometric synthetic aperture radar and prisms were reviewed from the available literature. The data from the mine’s satellite monitoring data and the ground-based radar instruments was analysed. Slope prediction methods were used to back-analyse the failures, to determine if failure prediction times were possible. A case study was incorporated from the neighbouring Rössing Uranium mine, to supplement the data. The data utilised for the study was downloaded from the slope monitoring instruments on the mine i.e., the interferometric synthetic aperture radar, ground-based radar and tension crack data. The following slope failure predictive tools were investigated; the strain deformation approach; the inverse velocity method; the slope gradient method; the acceleration and velocity approach; and Displacement/Time plots. The back-analysis work done proves that the following slope failure predictive methods were able to predict failure at least 3 days before failure: velocity, cumulative displacement and inverse velocity. It appears that the Husab mine failure mechanism is not as brittle as previously assumed and failures are not necessarily instantaneous. Therefore, failures should be identified early, and the necessary risk mitigation measures implemented proactively. The ability of back analysing large volumes of stored data is important in the study of failure prediction.
Support Design Approach for Crusher Chambers: A Case Study of Palabora Mining Company
(University of the Witwatersrand, Johannesburg, 2023-01) Masole, Nyeleti Venus; Stacey, T.R.
This report project aimed to design a support system for crusher chambers at Palabora. The research project focused mainly on the two crusher chambers (12m wide by 25m high and 61m long) planned for the Lift 2 project as part of the ore handling system. The main research questions that the researcher sought to answer were; what are the differences between Lift 1 & Lift 2 in rock mass characterisation, classification and the ground control district?; how suitable is the Lift 1 crusher chamber support system for Lift 2?; what could be support requirements for Lift 2 crusher chambers in terms of empirical, analytical and numerical design methods and what are the recommended support design approaches for Lift 2 crusher chambers? The methodology used to design support for the Lift 2 crusher chambers was based on determining the expected failure mode first and then selecting suitable design methods to cater for the extent of failure. This study combined empirical and analytical methods to determine the failure mode and required support system. The results were then validated using Finite Element Method numerical modelling software called RS2 (Phase 2) from RocScience. Research findings revealed that the ground control district, classification and characterisation of rock masses differ slightly between Lift 1 and Lift 2. Jointing in dolerite dykes (DOL) was slightly dense in Lift 2 compared to Lift 1 and was associated with increased mining depth. Furthermore, the Lift 1 crusher chamber support system was found to be suitable for Lift 2 but must incorporate dynamic support. Unwedge (RocScience) analysis simulated wedge type of failure in the crusher chamber walls. The empirical and analytical design approach proposed cable bolt lengths of between 6m and 9 m and 3-4 m for roof bolts with bolt spacing of 1.4 m and 1.0 m respectively. The simulation results using RS2 confirmed that the cable bolt length and spacing were appropriate. The recommended support system was expected to provide sufficient support to the crusher chamber in terms of controlling rock mass deformation and yielding. The general conclusion was that the design approach selected for crusher chambers must be able to adequately represent rock mass behaviour and the support required to maintain long-term stability.
The Impact of Digital Technology in South African Coal Mining: A Financial Performance Analysis of Anglo Coal American, Bhp Billiton and Glencore
(University of the Witwatersrand, Johannesburg, 2023-10-27) Maluleke, Reply; Neingo, Paskalia; Marshall, Tania R.
Digital technology, typically, refers to electronic tools, resources, devices and systems that store, generate and process information rapidly. Digital technology and innovation are among the initiatives that can assist mining companies to realise productive, efficient, profitable and sustainable mines. As such, the mining industry is taking steps towards digital technology and innovations that have evolved in recent years. The objective of this report was to discuss the financial impact of digital technology of the selected South African thermal coal mining companies namely Anglo American Coal Division now operating as Thungela Resources, Glencore, and South32, previously spun out of BHP Billiton and now operating as Seriti Resources. Coal mines were selected for analysis, due to their importance with respect to energy generation in South Africa. Industry cost curves over the period 2013-2019 were constructed as part of the financial analyses to show the trend of the selected companies’ unit costs. The research also used other financial analysis methods such as operating profit, profitability ratios, Economic Value Add and Du Pont analysis to analyse the performance of these companies. There appeared to be no production and unit cost improvement directly linked with investment in digital technology, as breakdowns, commodity prices, depletion of reserves, selling of operations, mine closures, high contracting prices, inflations and other factors also affected these parameters. Results for Anglo Coal and South32 did not indicate consistent good or improved financial results in all the financial analysis methods post the investment years in digital technology, in contrast to Glencore’s results which did. Glencore also invested more capital in digital technology as compared to Anglo Coal and South32. It is suggested that this may be one reason for its success. Consequently, it is recommended that companies looking to invest in digital technology follow the example of Glencore and invest as much capital as possible in this venture in order to maximise its potential.
The incorporation of unmanned aerial vehicles in a slope stability monitoring system: a Rössing uranium mine case study
(2024) Shanyengana, Olga Ndapewoshali
Slope 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.
The underrepresentation of technical women in executive and board of directors’ roles in the ten largest listed mining companies in South Africa
(2022) Zulu, Noluthando
As 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.
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, Jacques
Accurate 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.
Verifying the Quality and Performance of Grout Using Sensor Technology
(University of the Witwatersrand, Johannesburg, 2023-10) Hadebe, Menzi Bright; Mitra, Rudrajit
Underground mines systematically install ground support to stabilize excavations and provide safe working environments. Support units, such as rock bolts and cables, are commonly filled with cementitious grout to effectively prevent corrosion, maintain bonding behaviour between the support unit and grout, and enhance the load transfer between the grout and surrounding rock mass. The grouting process is however time consuming and labour-intensive, which leads to haphazard installations. These substandard grout installations are only observed after rock fall instabilities occur when the quality and extent of grouting inside a support hole are exposed and can be observed. The need to monitor grout installations increased (provide assurance) but remained a challenge due to the invisibility of grout inside the support hole. The invisibility of the grout column inside the support hole renders the routine quality control inspections of installed support units ineffective. This ineffectiveness of quality control inspections has led to a growing need to monitor grout installations with smart technologies to provide quality assurance of full-column grouting. In its current state, grout technology in the mining industry can only measure the extent of grout inside a support hole directly after installation (limited battery life). It cannot measure the loss of grouting material into near borehole fractures, shrinkage, quality of grout inside the support hole or its impact on support performance. These factors are critical to the success of an effective support system and pose a significant safety risk when overlooked. This research report will describe how grout sensor technology data was recorded and used to verify the extent and quality of cementitious grout inside support hole installations at laboratory and deep-level mine study sites. Grout sensor technology, in practice, utilizes several grout sensors placed at predetermined positions along a support unit with a receiver attached to the collar of the support hole. Electrical resistivity data from each sensor is collected using a grout detector. Depending on the position of each grout sensor, the extent of grout inside a support hole can be confirmed, hence eliminating the need for speculative and ineffective visual observations. The non-destructive verification and prediction of the quality and performance of grout inside support holes using sensor technology forms an invaluable strata control tool that can be used to identify sub-standard grouting operations and significantly improve safety at underground mines. This novel and innovative technology is a mining industry first.

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Browsing Faculty of Engineering and the Built Environment (ETDs) by School "School of Mining Engineering"

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