Theses and Dissertations (Mining Engineering)

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Prediction of creditworthiness of a viable artisanal and small-scale mining operation
(University of Pretoria, 2022) Meyer, L.D.; daneniowo@gmail.com; Eniowo, Olushola Daniel
The purpose of this study is to formulate models for the prediction of creditworthiness of a viable Artisanal and Small-scale Mining (ASM) operation. ASM is a form of mining carried out by mostly informal miners using minimal mechanisation, which affects their level of output and productivity. The use of inefficient tools for extraction and processing also lead to safety, health and environmental hazards. In order reduce the negative tendencies of ASM and still enhance its productivity, formalising and upgrading the operations to a more responsible form of small-scale mining has been recommended by previous studies. However, formal lenders, such as banks, perceive ASM operations as very risky ventures and so they usually avoid investing in such operations. Consequently, the miners have had to settle for informal sources of financing and interventions from governments and international donors. However, these types of funding are usually short-lived, and do not always align with a business-led approach to developing sustainable long-term solutions. There is therefore a need for ASMs to be able access formal sources of funding. This problem necessitates the formulation of models that could assist a formal lender or an accounting officer of a formalised ASM operation to assess the viability of the operations for the purpose of accessing formal lending. In order to achieve the aim of the study, a mixed form of research was carried out involving qualitative and quantitative research. A selective survey design was adopted for the study and Southwest Nigeria was selected for the research owing to the region’s richness in all the mineral categories usually targeted by ASM operators. The government ministry that regulates ASM was contacted with a view to obtain a list of ASM cooperatives and associations. The heads of these cooperatives and associations were then interviewed to provide their perspectives on the credit constraints in the industry. Also, a formal lender, which is a government-owned development finance bank (Nigeria Bank of Industry, BOI) that lends to ASM operations was contacted for qualitative study. The aim is to acquire the bank’s parameters for estimating creditworthiness of a competent loan application from an ASM borrower. The major parameters include: the licensing status of the operation; availability of loan guarantee in form of physical collateral or a guarantor to stand as surety; ability to afford the bank’s interest rate; membership of the mine operator in a registered cooperative society; availability of feasibility study report; and availability of ore reserve estimate. Based on the parameters obtained from the bank, a well-structured questionnaire was developed and was used to conduct quantitative research on a sample of 100 ASM respondents (one respondent per operation). Analysis of the research data was done using R programming language on RStudio which helped to develop simple and multiple regression models for creditworthiness of a viable ASM operation. The key findings from the study were duly presented based on descriptive and inferential statistics. The study recommends among others that future study direction should consider modifying, scaling, and improving available models for proving the viability of ASM operations.
An investigation into the use of backfill to reinforce pillars in hard rock bord and pillar layouts
(University of Pretoria, 2023) Malan, Daniel Francois; divine.ile98@gmail.com; Ile, Divine-Ito
The production of tailings is inherent to mining and minerals processing and will remain so for the foreseeable future. Catastrophic tailings dam failures, such as those at Canada’s Mount Polley in 2014 and Brazil’s Samarco and Brumadinho in 2015 and 2019, are a reminder that more needs to be done to safeguard lives, improve production, and protect the environment. As the global population increases, so does the demand for the metals and minerals required for modern life. With increased demand and supply comes the challenge of extracting greater value from low grade deposits, mining deeper ore bodies, and increased mineralogical complexity, all of which have the potential to lead to a higher production of tailings. This study was an investigation of the potential benefits of using the tailings as backfill in bord and pillar mines with specific emphasis on its use to increase the strength of the pillars and reduce the volume of tailings stored on surface. The literature indicated that backfill is extensively used in Chinese coal mines in conjunction with high extraction mining methods, mostly for environmental considerations. However, it is not commonly used in hard rock bord and pillar mines. This study explored the use of backfill to increase the extraction ratio in hard rock bord and pillar mines at increasing depths. The typical decrease in extraction ratio with increasing depth is illustrated in the dissertation with the aid of a simple analytical model, which emphasises the need to study backfill as an option to ensure viable mining operations in future. To simulate the effect of backfill confinement on pillar strength, an extension of the TEXAN limit equilibrium model was explored in this study. The model can simulate the failure of the pillars as well as the effect of confinement applied on the edge of the pillars. A simple plane strain model of the limit equilibrium model, with the confinement component, is derived in this study to study the attributes of the model. This was used to illustrate the effect of the backfill confining stress on the normal pillar stress in the failed zone of the pillar. An increase in confinement results in a substantial increase in stress carried by the failed pillars. This was also illustrated by conducting numerical modelling of an idealised bord and pillar layout with increasing levels of confinement. The intact core of the pillars increased in size for a larger magnitude of confinement and the resulting average pillar stress (APS) of the pillars also increased correspondingly. These preliminary models indicated that the limit equilibrium model with the confinement component behaves as expected. The magnitude of confinement that will be exerted by backfill on the pillar sidewalls is unknown. This study used a combination of literature sources and earth pressure theory to estimate the level of confinement that can be expected when placing backfill. Lateral earth pressure refers to the pressure that soil exerts in the horizontal direction, and it is an important parameter for the design of geotechnical engineering structures such as retaining walls. The analysis and historic studies indicated that a value of 0.05 MPa is a possible realistic value of confinement that will be exerted by the backfill. Numerical modelling of an actual platinum mine layout was done to illustrate the beneficial effect of backfill on pillar stability at greater depths. This illustrated that the zone of failure decreases for increasing confinement and there is a substantial reduction for a 2 MPa confinement value. It is nevertheless doubtful whether such a magnitude of stress will be exerted by the backfill unless there is substantial pillar dilation. Calibration of the actual confinement exerted by the backfill needs to be done as future work. Trial backfill sections in mines with sensitive instrumentation in the backfill will, therefore, be required to quantify this effect. In summary, the confinement limit equilibrium model proved to be a valuable approach to simulate the effect of backfill confinement on pillar strength. Mining areas where the pillar strength is reduced due to the presence of weak layers may benefit significantly from the placement of backfill. Additionally, the use of backfill will also reduce the requirement for tailings storage on surface, thus minimising the risk of environmental damage.
A Critical Investigation into Identifying Key Focus Areas for the Implementation of Blockchain Technology in the Mining Industry
(University of Pretoria, 2023) Webber-Youngman, R.C.W.; keatonphilo@gmail.com; PHILO, KEATON
The value of digital information is ever-increasing as more companies utilize digital technologies such as Artificial Intelligence (AI) and the Internet of Things (IoT) to gain deeper insight into their business operations and drive productivity gains. It is therefore important to safeguard and ensure the integrity of digital information exchange. Blockchain technology (BCT) was identified as potentially providing the mining industry with a trusted system for securely exchanging digital value. However, there is little evidence or understanding of how/where BCT can be implemented and what benefits the industry could obtain. This research study provides a fundamental understanding of what the technology is in order to identify the associated capabilities and potential application benefits for the mining industry. From a technology push perspective, blockchain capabilities are used to evaluate how the technology’s value drivers map to the mining industries core value chain processes. This was done to identify potential focus areas within the mining enterprise for further research and development of blockchain applications.
The application of probabilistic logic to identify, quantify and mitigate the uncertainty inherent to a large surface mining budget
(University of Pretoria, 2014-01) Webber-Youngman, R.C.W.; Yadavalli, Venkata S. Sarma; ronny.webber@up.ac.za; Hager, Johann
Mining is a hugely expensive process and unlike manufacturing is based on an ever diminishing resource. It requires a continuous infusion of capital to sustain production. A myriad of factors, from the volatility of the markets to the surety that the minerals are really there, “plagues” both management and investors. The budget tries to predict or forecast future profits and acts as a roadmap to all stakeholders. Unfortunately, most of the time the budget of a mine degenerates to the extent of a collapse, sometimes very soon into the new budget period. This problem plagues both small and large mines indiscriminately. The budget is dictated in absolutes, and little or no variability is allowed. This thesis aims at developing a process to predict the probability of failure or success through the application of probabilistic logic to the simulation of the budget. To achieve this, a very detailed modelling tool is required. The model must replicate the actual mining process both in time and actual spatial representation. Enabling technology was developed over a period of five years, primarily based on the Runge Software Suite. The use of activity based costing enabled the budget to be simulated and expressed as a probability distribution. A Pareto analysis was done on the main cost drivers to extract the most important elements – or key drivers - that need to be manipulated. These distributions were mapped against real data and approximated with the use of the three parameter Weibull distribution. Simulation using Xeras® (Runge) proved to be impossible. This is due to the time needed for setup and processing. The budget was described as an empirical function of the production tonnages split according to the Pareto analyses. These functions were then utilised in Arena® to build a stochastic simulation model. The individual distributions are being modelled to supply the stochastic drivers for the budget distribution. Income, based on the sales, was added to the model in order for the Nett profit to be reflected as a distribution. This is analysed to determine the probability of meeting the budget. The underlying analysis of an open pit mining process clearly reflects that there are primary variables that may be controlled to trigger major changes in the production process. The most important parameter is the hauling cycle, because the haul trucks are the nexus of the production operation. It is further shown that the budget is primarily influenced by either FTE’s (full time employees, i.e. bodies) or funds (Capex or Opex) or a combination of both. The model uses probabilistic logic and ultimately culminates in the decision of how much money is needed and where it should be applied. This ensures that the probability of achieving the budget is increased in a rational and demonstrable way. The logical question that arises is: “Can something be done to utilise this knowledge and change behaviour of the operators?” This led to (IOPA – Intelligent Operator Performance Analyses) – where the performance or lack thereof is measured on a shift by shift basis. This is evaluated and communicated through automated feedback to the supervisors and operators and is being implemented. Early results and feedback are hugely positive. The last step is prove where capital (or any additional money spend) that is applied to the budget will give the most benefit or have the biggest positive influence on the achievement thereof. The strength of the model application lies therein that it combines stochastic simulation, probability theory, financial budgeting and practical mine schedule to predict (or describe) the event of budget achievement as a probability distribution. The main contribution is a new level of understanding financial risk and or constraints in the budget of a large (open pit) mine.
Developing a concept that can be used to quantify the motion of flyrock, with the intention of eventually producing a measuring tool for future flyrock research.
(University of Pretoria, 2019) Spiteri, William; jennifer.vanderwalt@up.ac.za; Van der Walt, Jennifer
Flyrock remains a significant risk to the health and safety of the mine’s employees and infrastructure as well as the safety of the neighbouring communities and their property. Losses and damages can result in significant financial and reputation consequences. The lack of fundamental research in recent years and quantifiable data relating to the relationship between blast design parameters and the risk of flyrock motivated this project. A number of authors concluded that major gaps in knowledge relative to flyrock caused by its random nature still remain a weakness in the field. Recent papers published (since 2010) proposed a wide range of potential approaches and techniques to predict or investigate flyrock. However, the majority of these papers concluded that the proposed results were site-specific and could not be applied to other environments. The focus of this project was to develop a concept that is able to quantify the flight path of the flyrock resulting from a blast. The motivation behind the development of this concept was to enable future researchers to quantify the impact of the different blast design parameters on the measured flyrock. Various technologies were considered and investigated during this project. After a comparative analysis of these technologies, it was decided to use photogrammetry as the foundation of the proposed concept tool. The proposed concept consists of three main phases, namely (1) data acquisition, (2) image processing and data analysis and (3) data interpretation. To date, progress has been achieved with phase one and phase two. In phase one, all objectives have been met. However, there are still areas which need refinement, specifically regarding the placement of the cameras in the field. In phase two, success was achieved with the proof of concept exercise in a controlled environment using a clay pigeon as the projectile. The process of calibrating the lenses has been established, however, further optimization is possible. Point-cloud data was successfully generated in the concept test, but converting the image data from subsequent quarry test blasts proved more challenging and is still a work in progress. Once phase two has been satisfactorily resolved, attention will focus on phase three. Results to date have given a positive indication that the concept is viable and that additional work will prove the technology functional. Ultimately, it is envisioned that this tool can be used for one of three purposes, namely: • Mines can generate a database with accurate historical flyrock of their blasting operations. • Research teams can implement this tool to conduct quantitative research and investigations into flyrock and the impact of different blast design parameters on the risk of flyrock. • Point-cloud data combined with ballistics calculations can be used to visualise blasts and flyrock in Virtual Reality for training and education.
Structural mechanisms contributing to large-scale hangingwall instabilities on the UG2 reef horizon
(University of Pretoria, 2019) Malan, D.F.; u28109105@tuks.co.za; Hartzenberg, Alida Gertruida
Structural complexities, including regional geologic structures, low-angle structures, ramp structures and alteration zones contribute towards large-scale hangingwall or structural (pillar) instabilities experienced in many UG2 chromitite mines. The associated anomalous behaviour of the rock mass caused by these structures may result in significant ore reserve write-offs. The inability of technical and underground mining personnel to pro-actively identify and treat these geologic structures and associated failure mechanisms has resulted in ongoing instabilities experienced in many mines. Anomalous behaviour is mostly as a result of the exposure of numerous low-angle structures on various scales, commonly known as ‘doming’. These low-angle structures are treated simplistically or go unnoticed. Also, the presence of pegmatite veins, which is a common joint characteristic, causes problems and is generally ignored as the potential for instability. Furthermore, the presence of alteration zones is typically unnoticed as it is not common. The exposure of these prominent structures or a combination of these structures can impact on the exposed hangingwall conditions, panel span, support- and pillar behaviour. In some instances the impact have resulted in multiple fatalities and total mine closure. Case studies were conducted by the author at the Lonmin Marikana Operations where large-scale instabilities have been experienced. These findings were related to other similar study sites in the Bushveld Complex and the Great Dyke in Zimbabwe. The investigations confirmed some of the findings made by previous studies. However, new information gained from this study provided an improved understanding of the formation, interaction and potential instabilities if these structures are exposed by mining. The formation of the Bushveld Complex and geologic structures contributed to the anomalous conditions experienced in some underground mine workings. With the application of a new technology by the author (a sub-surface profiler), for the first time, the presence and location of these anomalous structures could be verified in the hangingwall. This contributes to an improvement in the spatial interpretation of these structures and confirmed that it should be considered in the mining strategy and support design processes. The learnings from the study will assist with the early detection of specific structural conditions which may contribute to the mitigation of potentially unstable conditions. Suitable remedial strategies were developed by the author from the site investigations and are discussed in detail. This includes the application of preferred mining layouts, mining direction, spans and support strategies where these structures are present. This work may significantly reduce the risk of large-scale instabilities and is therefore considered a significant contribution towards improving safety and the understanding of these anomalous structures at the mines in the Bushveld Complex.
Structural mechanisms contributing to large-scale hangingwall instabilities on the UG2 reef horizon
(University of Pretoria, 2019) Malan, D.F.; u28109105@tuks.co.za; Hartzenberg, Alida Gertruida
Structural complexities, including regional geologic structures, low-angle structures, ramp structures and alteration zones contribute towards large-scale hangingwall or structural (pillar) instabilities experienced in many UG2 chromitite mines. The associated anomalous behaviour of the rock mass caused by these structures may result in significant ore reserve write-offs. The inability of technical and underground mining personnel to pro-actively identify and treat these geologic structures and associated failure mechanisms has resulted in ongoing instabilities experienced in many mines. Anomalous behaviour is mostly as a result of the exposure of numerous low-angle structures on various scales, commonly known as ‘doming’. These low-angle structures are treated simplistically or go unnoticed. Also, the presence of pegmatite veins, which is a common joint characteristic, causes problems and is generally ignored as the potential for instability. Furthermore, the presence of alteration zones is typically unnoticed as it is not common. The exposure of these prominent structures or a combination of these structures can impact on the exposed hangingwall conditions, panel span, support- and pillar behaviour. In some instances the impact have resulted in multiple fatalities and total mine closure. Case studies were conducted by the author at the Lonmin Marikana Operations where large-scale instabilities have been experienced. These findings were related to other similar study sites in the Bushveld Complex and the Great Dyke in Zimbabwe. The investigations confirmed some of the findings made by previous studies. However, new information gained from this study provided an improved understanding of the formation, interaction and potential instabilities if these structures are exposed by mining. The formation of the Bushveld Complex and geologic structures contributed to the anomalous conditions experienced in some underground mine workings. With the application of a new technology by the author (a sub-surface profiler), for the first time, the presence and location of these anomalous structures could be verified in the hangingwall. This contributes to an improvement in the spatial interpretation of these structures and confirmed that it should be considered in the mining strategy and support design processes. The learnings from the study will assist with the early detection of specific structural conditions which may contribute to the mitigation of potentially unstable conditions. Suitable remedial strategies were developed by the author from the site investigations and are discussed in detail. This includes the application of preferred mining layouts, mining direction, spans and support strategies where these structures are present. This work may significantly reduce the risk of large-scale instabilities and is therefore considered a significant contribution towards improving safety and the understanding of these anomalous structures at the mines in the Bushveld Complex.
A critical investigation into missing persons in underground mines and related tracking technology
(University of Pretoria, 2018) Webber-Youngman, R.C.W.; u10142127@tuks.co.za; Ngwenyama, Philani Larrance
Even though mining has always been at the heart of the economy, it is also regarded as one of the most hazardous industries. Miners and any other persons who work underground can, not only be fatally injured during mining accidents, but also from being trapped underground. This study shows that there is a significant number of fatalities caused by miners going missing underground. These miners are deceased due to being trapped underground for an extended period of time without any help. These fatalities are often incorrectly reported, attributing the fatalities to the initial event. This study shows that the miners can survive the initial event, but become trapped in unknown, life threatening locations. Several accidents that led to miners going missing were investigated. It was found that the lack of positioning information regarding the missing miners causes search-and-rescue operations to either fail or last longer. This study shows that the miners who were deceased from being trapped/lost underground could have been saved by such a system that can urgently provide their locations. A slow implementation of these systems in mines could suggest a failure to learn by the industry; in realising the need and value of these systems. The aim of this study was to firstly emphasize the need and value of these systems in underground mines. Secondly, to make the industry aware of the availability of different systems in the market. Lastly, to define and recommend a suitable and fit for purpose system. The identified systems are mainly classified into Through-the-Wire (TTW), Through-the-Air (TTA) and Through-the-Earth (TTE) systems according to their signal transmission techniques and frequency spectrum. TTW systems transmit signals through cable connections. The TTW systems are used as phones or network infrastructure. TTA systems enable the exchange of signals wirelessly in the air as a medium of signal transmission. TTE systems propagate seismic or electromagnetic signals through rock. The functions, capabilities and limitations of these systems were investigated. Furthermore, devices used for similar purposes in related industries with the potential to be adopted in the mining industry were studied. Several factors that can affect the suitability and applicability of these systems in underground mining environments were investigated. With a wide variety of systems commercially available, there was a need to determine the most suitable and fit for purpose system. This was done by, firstly developing user requirements that resemble an ideal system. Secondly, the underground areas in which miners are expected to work and travel were identified. Lastly, from the investigated accidents, scenarios in which miners can go missing were derived. These parameters were used to evaluate the suitability of the systems. Therefore, the most suitable and fit for purpose system can thus be selected based on the evaluation outcomes. Even though all these systems worked well, it was found that no single system could satisfy all the user requirements, no single system was suitable in all the underground areas and no single system was suitable for all the going missing scenarios. This necessitated the need to assess the possibility of integrating different systems to improve suitability and effectiveness. It was recommended that mining operations identify further scenarios in which persons can go missing, especially those that are more relevant to their underground areas. The user requirements and underground areas should be considered and used for selecting a suitable system. The mining industry needs to learn and realise the need and value of these systems to save lives.
A preliminary evaluation of a hydraulic mechanical splitter as a means of breaking rock in a deep-level mine
(University of Pretoria, 2018) Spiteri, William; u04333519@tuks.co.za; De Graaf, Wolter Willem
Conventional drill-and-blast practice in deep-level hard rock mining impacts negatively on the immediate environment and alternatives are frequently sought for efficient, continuous, automated and safe rock breaking. The current method for breaking rock, drilling and blasting, is a “cyclic” activity where the rock mass is drilled, blasted, cleaned and the area supported. The mining process must be completed within the blasting times. Continuous rock breaking presents the opportunity to eliminate the “cyclic or batch” mode and improve productivity. Such a system for non-explosives continuous rock breaking is the hydraulic rock splitter. The choice for the splitter is the equipment is relative simple, easy to use, readily available and affordable, and has been successfully used in the construction and civil industries. The purpose of this study was to evaluate the functionality and applicability of the hydraulic mechanical splitter in deep-level hard rock mining. The specific instrument used in the study was the DARDA® hydraulic splitter. Rock breaking with the use of a hydraulic splitter has a place in niche applications in an underground mining operation. The static hand-held tool has distinct advantages in restricted areas. The unit is simple in design and is easily integrated into existing mining operations, and neither does it require a highly technical skilled workforce or expensive maintenance. A literature study was undertaken, with the main focus on non-explosives rock breaking where a hole needs to be drilled into the rock mass. A device or application is inserted into the hole to fracture the rock mass. The specific DARDA® hydraulic splitter used during the trials required a hole diameter of 45mm to 48mm and a minimum hole length of 680mm. Several trials were conducted on surface and underground. The most challenging process in mechanical rock splitting is to create a free face in the stope. In the trials four different “cut” layouts were evaluated to create a second free face. The trials highlighted the importance of quality drilling in terms of collaring the hole, hole length and directional accuracy. The results showed the potential of the DARDA® hydraulic splitter. Drilling the least number of holes produced the least amount of rock. The greater the cross-sectional area of holes drilled, increased the amount of broken rock and resulted in easier splitting, due to the increased void. The mass of rock broken per cut varied between 30 kilograms to 65 kilograms with cross-sectional areas of 0.09m2 and 0.144m2 respectively. The operational learning included the frequent lubrication of the feathers and the wedge. The unit needed to be supported during the splitting process, small rock fragments were caught between the moving parts. Fragments deep inside the “cut” area had to be removed manually and during the splitting process, starting at the hanging wall, obscured the holes close to the footwall due to rock fragments on the footwall. To alleviate a number of operational issues experienced during the trials, include the automation of the lubrication of the feathers and wedge, supporting the cylinder unit during the splitting process and small stones wedged between the moving parts to be removed prior to inserting the splitter into the next pre-drilled hole. The cross-sectional area of the cut should be as large as possible for the rock fragments to easily fall to the foot wall and the splitting process should start from the bottom to the hanging wall to not obscure the drilled holes with rock fragments.
The development of a mining method selection model through a detailed assessment of multi-criteria decision methods
(University of Pretoria, 2018) Meyer, L.D.; u12115500@tuks.co.za; Baloyi, Vukosi Danisa
In the past decades, attempts were made to build a systematic approach to mining method selection (MMS) Ooriad et al, (2018). This is because MMS is a complex and irreversible process. Since it can affect the economic potential of a project, the approach must be as thorough, precise, and accurate as possible. The key challenges of the previously established techniques such as the Nicholas and Laubscher method are that, there was a lack of engineering judgement in the process of selecting a mining method. In other instances, not all the parameters required in the mining method selection process were considered; i.e. economics would be the basis of the final decision of a mining method without taking into consideration other factors such as geology (Bogdanovic et al, 2012). While other techniques just considered a few parameters and a limited number of mining methods as alternatives (Namin, 2008). Some techniques were customised procedures for a specific orebody (Namin et al, 2009). Each orebody is unique; therefore, the approach of just adopting the same mining method for similar commodities was not always an effective or realistic approach Therefore, the existing procedures were found to be inadequate and not applicable for consideration in all MMS processes. To solve the challenges stated above, an up-to-date approach to MMS is the use of multi-criteria decision-making (MCDM) tools to aid in the process. The MCDM are effective in facilitating a decision-making process; however, the use of MCDM has not gained enough popularity across countries and in the mining industry especially in MMS (Mardani et al, 2015). Their successful implementation in other industries such as in manufacturing companies, water management, quality control, transportation, and product design (Lee et al, 2007)present an opportunity for further exploration in MMS. In this research, these MCDMs were further explored as starting point to solving the challenge faced in MMS. With the aim of developing a systematic and an unbiased approach that caters for subjective and objective analysis in MMS, this study investigated 10 MCDMs- TOPSIS, TODIM, VIKOR, GRA, PROMETHEE, OCRA, ARAS, COPRAS, SAW, and CP with potential to solve the MMS challenge. The study focused on deriving a model where the MCDMs can be integrated and be successfully used for MMS. Included in the research are factors and mining methods that are necessary MMS. The aim was to use the factors and mining methods as inputs to the developed MMSM. In the result section, case studies were used to analyse the MCDMs following a descriptive and a statistical analysis (sensitivity analysis, spearman correlation, and Kendall’s coefficient.). PROMETHEE, TOPSIS, and TODIM stood out as methods for use in the selection of mining method in the coal mining industry. From the research findings, it was generally concluded that OCRA, ARAS, CP, SAW, and COPRAS are simplified approaches of the afore-mentioned methods. VIKOR’s rankings were outlying and the conclusion was that it was not a suitable method for MMS. GRA’s conclusion based on the literature view was that there remain many unanswered questions about its mathematical foundations. The MMSM was developed using the results obtained. In the MMSM, first, the user defines the problem. The approach is of case-based reasoning (CBR); where the user can retrieve, re-use, revise and then retain the information (in the database) for future use. The user can always search within the database for a similar problem to select a MCDM, factors and methods; and this may be one of the future areas of improvement on the developed MMSM because there are a number of factors, MCDMs, and mining methods that the user may need to go through before getting to the relevant MCDM. One of the recommendations made by the author was that the user must understand the theoretical background of the MCDM before using it in the MMSM. In future studies, algorithms for selection of a suitable MCDM in the MMSM can be developed so that once the problem has been defined and structured; the user may not struggle with knowing which method to use amongst the suggested. Also, an application-based approach may be investigated further.
An Investigation into Using Remotely Piloted Aircraft System Technology for Decision Making Regarding Block Lifecycle Activities in Surface Mining
(University of Pretoria, 2018) Spiteri, William; alton.bester@gmail.com; Bester, Alton Wynand
The process of mining is about executing a few, seemingly easy, routine activities with consistency and precision over an extended period of time. The research that has been conducted during the course of this study has attempted to determine whether RPAS (Remotely Piloted Aircraft System) technology (also known as drone technology) can assist operational mining staff in making better, more informed decisions regarding activities related to the physical mining process. In this study the mining process is referred to as the block lifecycle, which consists of four primary activities, namely cleaning (block preparation), drilling, charging & blasting and loading & hauling. The study was conducted at an iron ore mine located in the Northern Cape province. To understand the benefits that RPAS technology could provide to the mine it was important to understand the baseline - the current data and information that was available to managers for the purposes of decision making. Once the research was complete, a comparison could be done between the baseline and the information that RPAS technology can provide. During the baseline analysis it was found that activities without formal systems, such as cleaning and charging, provide a challenge for managers, as there is a lack of information from which they can make decisions. Activities performed by contractors such as drilling, loading and hauling also present an incomplete understanding of performance, as most information is available in a summarised format and is quantitative, rather than qualitative, in nature. For example, the question is posed: “did the contractor drill the planned number of metres for the day?”. A more informative alternative to that question would be: “did the contractor drill the required number of holes to the correct depth in the correct position?”. Activities where fleet management systems are used, such as the mine’s drilling equipment (Flanders ARDVARC®) and the loading and hauling equipment iii (Modular Dispatch®), provide vast amounts of information on which managers can base their decisions. In order to collect data a DJI Phantom 4 Pro RPAS unit, fitted with a 20 megapixel camera, was used to conduct flights. Each flight focused on acquiring data, in the form of photographs and/or video footage, related to a particular mining block. Flights were undertaken by qualified and authorised RPAS pilots representing a service provider called UDS (UAV and Drone Solutions (PTY) Ltd). Once the in-field data collection process was complete, processing of the data commenced. The primary output of the data processing step was an orthophoto. The orthophoto was then processed to obtain a point cloud. Then finally, the point cloud was processed to create a digital terrain model. Additional insights were obtained through analysis in specialised software packages such as Global Mapper and WipFrag. The study found that RPAS-generated data can provide information that will allow managers to monitor and validate progress of cleaning activities. Data related to drilling will allow managers to monitor and validate progress of drilling activities and drilling quality. Charging and blasting activities can also be assessed, as aerial imagery and high-resolution video footage can be captured before, during and after the blast. RPAS data can also be used for fragmentation analysis. Information related to loading and hauling activities can be enhanced with RPAS data, as it allows one to visually track progress and perform volume calculations that determine the amount of material which has been mined. This can only be done, provided there is sufficient data integrity that is largely controlled by ground control. RPAS technology can certainly assist managers in understanding conditions in the field and can aid better decision making for block lifecycle activities. The application of RPAS technology in the field of mining has shown some very promising results. The extent to which it becomes entrenched, however, will depend on the appetite of the industry to adopt the technology.
A critical investigation into value adding principles for conducting an open pit conceptual study
(University of Pretoria, 2017) Webber-Youngman, R.C.W.; Botha, Brendan William; hannobuys@gmail.com; Buys, Ockert
A conceptual study is regarded as the first phase in the development of a new open pit mine. The phased approach (conceptual, prefeasibility, feasibility) is described as a “stepwise risk reduction” process, whereby each phase progressively reduces risk prior to project implementation. As the first step in the process, the conceptual study could potentially have the largest effect on mine development since investment decisions are based on its content. Carelessly conducted, a conceptual study has the potential to underestimate a viable project or produce an overoptimistic valuation. In a tough economic climate, mine project developments are scrutinised, prioritising capital to develop assets with the most potential. To prioritise, conceptual studies need to be comparable and therefore based on a similar, structured approach. Comparability is hindered by low confidence geological information and assumptions on which conceptual studies are based. The time it takes to conduct a conceptual study and the associated accuracy are largely dependent on the information available since information is often borrowed from similar projects or developed from first principles. To prevent casual educated guesswork, conceptual studies need to be subject to a scientific, standardised approach with experienced professionals involved. At the core, a conceptual study can be broken down into a set of activities as is found in a work breakdown structure. Major mining companies have comprehensive internal standards (sets of activities) where the activity determines what needs to be included in a conceptual study and the deliverables that need to be achieved. This dissertation drew activities from industry standards and eight different case studies for consideration. Essentially, activities add value to a conceptual study by reducing technical and financial risk. For this reason, activities culminated from case studies and industry standards were evaluated by a focus group to determine the risk reduction potential of each activity. From the focus group evaluation, activities were ranked according to value adding potential, and a list of twenty activities was identified as critical to the success of a conceptual study. The top twenty activities were evaluated against the required conceptual study deliverables identified in the literature, and six additional activities were added, ensuring that all critical deliverables are met. In total, twenty‐six activities were identified that, if included in a conceptual study, would ensure that a standardised, scientific approach is followed and that a conceptual study would add value by reducing risk. In addition to the critical activities identified, this dissertation drew from the literature survey, case study results and focus group assistance such value adding principles critical for the success of an open pit conceptual study.
Investigating the stage-gate model as a research and development implementation process in modernising the mining industry
(University of Pretoria, 2016) Webber-Youngman, R.C.W.; u10501585@tuks.co.za; Preis, Eugene Pieter
In recent years, innovation in the mining industry has shifted from being a non-essential business activity to a necessity. Key challenges in the last decade (such as declining ore grades and increased mining costs) have forced companies to focus on innovative business initiatives in order to gain incremental cost and productivity improvements. These key challenges have placed the mining industry in a difficult position they are substantial and in many cases, complex in nature. In order to ultimately solve (and not merely mitigate) these challenges, fundamental innovation step-changes are required. The success of the potential implementation of these changes is to rethink the "starting point" of innovation, namely the research and development (R&D) strategy and process. Contrary to popular belief, innovation does not occur spontaneously. It is, in the majority of cases, a product of meticulous planning, thinking, testing, iteration, and implementation. This study investigated the Stage-Gate model as a potential R&D implementation process in solving the aforementioned challenges, and ultimately modernising the South African mining industry. The study focused on firstly deriving a skeleton Stage-Gate model, in order to conduct further research into the associated key gate criteria, stage activities and critical success factors. The research findings were used to develop a proposed Stage-Gate model, which was then assessed at the hand of a South African mining case study (Missing Person Locator System). From the research findings, proposed Stage-Gate model and the case study evaluation, it was generally concluded that the Stage-Gate model has the potential to assist in the successful modernisation of the South African mining industry (SAMI), through focused R&D efforts into the industry's key problem areas and challenges. The study further recommended that in general, the outcomes of the study should be used to conduct R&D in the SAMI, in order to more effectively and efficiently conduct R&D in the SAMI (and ultimately modernise the SAMI). Lastly it was suggested that the outcomes of the study (and in particular, the proposed Stage-Gate model) be tested through conducting an actual R&D effort into a new value proposition. The actual application of the proposed model will reveal the degree of value that the Stage-Gate approach could deliver, and could serve as proof that the Stage-Gate model and approach can work as a tool in modernising the SAMI.
Creating a technology map to facilitate the process of modernisation throughout the mining cycle
(University of Pretoria, 2016) Webber-Youngman, R.C.W.; Liebenberg, Andre; u10118200@tuks.co.za; Jacobs, Jonatan
The global mining industry is currently under pressure. The industry is in the midst of the largest mining super cycle since the Second World War. Mining companies face increasing challenges to profitability due to unfavourable commodity prices as well as increasingly tougher mining conditions, rising pressure from various stakeholders and numerous other mining challenges. Incremental improvements are no longer sufficient enough to sustain the mining sector, which explains why many leading organisations are rallying behind the innovation imperative that calls for major transformation. This is especially true with the impending technological revolution, where innovation will be the key to survival. This not only holds true for the mining industry, but for nearly all companies, businesses, organisations and governments worldwide. In the upcoming technological age, the line distinguishing different businesses and operations will become increasingly unclear. It is therefore vital to approach innovation from a holistic point of view. One driver to improve the innovation efforts of an organisation is to look at technology trends across various industries. Many technologies exist, or are in development, that may be applied to be used (or be modified and applied) in the mining industry. With the rapid rate of technological advancement world-wide, it is also important for the mining industry to remain aware of cross-sectorial innovations that may have an impact in future. This is especially true when it comes to exponential and disruptive technologies. Operational performance excellence relies on the innovative use of such technologies and to remain abreast with developments that may add value to a given component within the mining cycle. As a result, the mining industry will be increasingly focused on integrating all activities across the value chain. This includes the continued introduction and development of Integrated Remote Operating Centres, mechanisation and automation. Such technological advances and implementations in mining form part of the modernisation drive currently taking place in the South African mining industry. However, in order to accomplish such value-added end-goals the constituent technologies need to be evaluated in detail. From these and many other technologies, mining operations can also achieve multiple other benefits and "quick wins". While investigating these technological trends it was found that many different organisations, businesses, institutions and individuals conduct great amounts of research to identify technologies that are applicable, or potentially relevant, to mining. Often these studies complete the same research for the initial phases, prior to focussing in more depth on specific technologies. As a result, a need was identified for research in technologies that may add value to mining. By identifying starting points for further studies and R&D into specific technological solutions, many of these initial research phases may potentially be eliminated or reduced. The greater part of the mining industry is often not aware of emerging technologies that could potentially add value to their operations, or which may disrupt aspects of their business or even their daily lives. The impact or benefit of technologies has to be assessed in order to gain an understanding of how opportunities could be exploited or detrimental impacts negated. In doing so, an organisation may work towards enhancing its operational risk management strategies, minimise negative consequences from external technological factors, and identify potential improvements to an operation or the organisation as a whole. It is therefore vital for companies and individual operations to have access to a platform that can provide technology related information which needs to be accounted for. For this reason, a Technology Map was created that highlights technologies that may further be analysed in order to identify those technologies with sufficient potential to add value. The structure of the Technology Map was developed to include the main value drivers within the entire mining cycle, covering the exploration-, mine evaluation-, mine design-, operations-, and mine closure to post-closure mining phases. Various technologies, ranging from physical to digital technologies, were analysed. Those with potential to add value, or which need to be accounted for in order to avoid detrimental impacts, were slotted into the sub-categories, processes, activities, focus areas or specific challenges beneath the applicable value drivers throughout the mining cycle.
The design and behaviour of crush pillars on the Merensky reef
(University of Pretoria, 2015) Malan, D.F.; Du Plessis, Michael
Crush pillars are used as part of the stope support in intermediate depth tabular mining stopes. Crush pillar design should ensure that the pillars crush when formed at the mining face. This behaviour of the pillars is typically achieved when the pillars have a width to height ratio of approximately 2:1. Once crushed, the residual stress state of the pillars provides a local support function. Crush pillars are extensively used in the platinum mines of South Africa. In most cases effective pillar crushing is not achieved, resulting in pillar seismicity. The objective of the research was to determine the parameters which influence crush pillar behaviour. A limit equilibrium model was identified as being able to simulate the behaviour of the pillars. The model implemented in a displacement discontinuity boundary element code provided insights into the stress evolution of a pillar depending on its position relative to the mining face, the effect of over-sized pillars, the impact of geological structures, layout and rock mass parameters as well as mining depth. An underground mining trial was conducted at Lonmin Platinum to measure and visually observe the behaviour of crush pillars. This was the most comprehensive monitoring of these pillars ever conducted in the platinum industry. The visually observed behaviour of the pillars agreed well with the findings of the measurements and the pillar fracturing profiles obtained at various stages of the pillar forming cycle. A sequence and mode of pillar failure could be identified. The results indicated that a pillar reaches a residual stress state when separated from the mining face. The pillar experiences secondary, subsequent reductions in stress when new pillars are formed. This unloading phase, has in the past, typically only been referred to as continued strain softening behaviour. However, it was found that at some point the pillars experienced no further reduction in stress whilst the pillars continued to deform. This observation was verified by convergence measurements. After all mining stopped, continued convergence was recorded. A numerical model was used to back analyse the behaviour of the underground trial site which consisted of an approximately 22 000 m2 of mined area and 55 crush pillars. To date, no numerical modelling of a mine-wide tabular layout, which explicitly included a large number of crush pillars, had been reported in South Africa. This work is therefore considered a major novel contribution to this field of research. After model calibration, both the observed and measured behaviour of the crush pillars in the trial site could be replicated. This was especially useful in evaluating the stress conditions measured above the pillars as well as the total amount of convergence experienced adjacent to the pillars and at the panel mid-spans. The findings validated the use of the limit equilibrium model implemented in a displacement discontinuity boundary element code to simulate the behaviour of crush pillars on a large scale.
A critical investigation into spontaneous combustion in coal storage bunkers
(University of Pretoria, 2015) Du Plessis, J.J.L.; Webber-Youngman, R.C.W.; Govender, Soobramoney
In coal mining, spontaneous combustion can occur in many areas such as stockpiles, underground workings, waste dumps, coal faces, in-pit ramps and backfill areas. Spontaneous combustion has been defined as an oxidation reaction, which occurs without an external heat source. Although not limited to coal, the most significant hazard of spontaneous combustion is the fires that occur in coal mining operations around the world. These fires pose a serious risk to the safety of workers in the coal mines. This phenomenon also has an environmental impact, which can affect the quality of life for future generations. Extensive research work has been done and recorded about spontaneous combustion in coal stockpiles, dumps and coal faces, but very limited work has been conducted on raw coal storage bunkers. This study investigated the occurrence of spontaneous combustion in coal storage bunkers, and established that there is no single document available that addresses the problem adequately. Therefore, a need was identified to create a guideline with decision analyser steps to be able to arrive quickly at a possible solution to the problem. This work does not address spontaneous combustion in underground workings, waste dumps, stockpiles, coal faces, in-pit ramps and backfill areas. It was found that important factors affecting the possibility of SC occurring were the type of coal being supplied to the bunker, the mining practice with regard to the standing time of the loose cubic metres of coal on the mining benches, and the impact of the physical factors around the bunker. The information obtained could be of great significance when designing or trying to solve spontaneous combustion problems in raw coal storage bunkers. The guideline and decision analyser steps can be applied early in the phase of the project in order to minimise or eliminate similar mistakes made in the industry over the years.
Competitiveness and performance prediction of surface coal Mining Engineering
(University of Pretoria, 2016) Webber-Youngman, R.C.W.; Joubert, Johan W.; mdaniel@udsm.ac.tz; Budeba, M.D.
The purpose of this research is to formulate mathematical models for assisting the management of either a new or operating surface coal mine to assess its competitiveness relative to other coal producers for a given market of thermal coal. As an alternative of e ciency measurement to provide a new way to assess better the competitiveness of surface mining, Data Envelopment Analysis (DEA) method is proposed. DEA uses linear programming to determine the relative e ciencies of (competing) mines, each referred to as a Decision Making Unit (DMU). In this research, the methodology applied involves three stages: First, applying DEA to formulate the mathematical models basing on the structure of coal extraction, processing and supply to the markets. Second, evaluate the models performance and illustrate the use case, and thirdly develop predictive model for the e ciency and performance of a new mine. Three DEA models were developed, each representing a speci c con guration of extraction, processing and sale of coal to the markets. The main model, referred to as Combined System for Local and Export (CSLE), supplied both the local and export markets. Two special cases, referred to as Local Coal Mine Supply (LCMS) and Export Coal Mine Supply (ECMS) respectively, looked at the individual markets in isolation. The results from the numerical illustrations of the application of the DEA models showed that the models were able to discriminate between the e cient (best practice) and ine cient mines. This provides a quantitative measure that mining companies can use to benchmark themselves against other competitors in a multi-dimensional manner. Also, the proposed method allows for generating realistic, quantitative targets for those DMUs that are considered ine cient. After formulating the three DEA models, use cases are presented for the CSLE model to demonstrate the signi cance of the proposed model for decisions making. Predictive models for technical e ciency and mine performance developed in this thesis, target new mining operations wanting to enter the market. A statistical method known as supervised learning was employed in this case. It was found that the predictor variables in the model can only explain 54.5% of the variation in technical e ciency. To test the prediction accuracy, the mining entities were separated into training and test sets. On the test set, the model predicted e ciency scores within 20% of the actual (known) values. To improve the performance of this model, this thesis suggests investigating the in uence of qualitative variables on mining e ciency. Such qualitative variables may include worker morale, work satisfaction and salary disputes. Mine planning is non-trivial as it requires various perspectives and involves the interdependence of many variables with di erent units of measure. This research is signi cant as it provides mining management with a sound and rigorous model to handle the multiplexity of the decision variables. The quantitative approach provides for evidence-based decision support where large capital amounts are at risk. Mine planning parameters can be evaluated taking the mine's particularities into account before proceeding to the production stage. The DEA approach is useful both for current mining operations to evaluate its competitiveness in given markets, as well as new mining operations who need to anticipate the type and quantity of capital to invest given their project characteristics. Therefore, the mine management can use the models to determine the optimal technical inputs such as capital, labour and the stripping ratio while considering mine-speci c challenges that in uence the competitiveness of the project, such as the location of the mine from the market and coal seam thickness that can not be controlled.
Planning mechanised cave with coarse fragmentation In kimberlite
(University of Pretoria, 1998) Brown, A.N.; Bartlett, Patrick John
Premier Diamond mine had to plan, develop and operate a low cost, mass mining method to recover extensive ore reserves below a 75 metre thick, dipping gabbro sill. The mining method had to preclude the extraction of as much of the 52 million tons of barren waste contained in the gabbro sill as possible and ensure the safety of personnel and operations. Consequent on the failure of the open stope mining method first attempted, a geotechnical investigation showed that ore recovery by caving methods was possible. The fragmentation that reported to the drawpoints would be coarse and the production horizon would be situated in relatively weak rock. The increased depth or mining, experience on the mine in using LHD's, changes in mining technology and the high production rate required, determined that Premier Diamond Mine could implement a mechanised cave using LHD's for ore extraction. Parameters that need to be defined to successfully exploit any orebody considering cave mining methods include (Cummings et al., 1984 ): * The area that must be undercut to induce continuous caving. * The fragmentation that will result as the orebody caves and the fragmentation size distribution that \viii report to drawpoints. The size distribution will determine drawpoint spacing, secondary blasting procedures and equipment. ore pass diameters, as well as tunnel and LHD sizes. * The rock mass response to the mining operations must be understood and used to optimise the mining sequence. Once the rock on the production level has been damaged by high abutment stresses, maintaining the stability of excavations can be expensive and time consuming. * Support systems and time or installation must be carefully planned and controlled. The function and potential method of failure of the support clements must be understood * Draw control and analysis or draw control data is important to ensure that premature waste ingress is minimised and that stress related problems that can result in cave-sitdowns" do not occur. Research was undertaken by Premier Mine personnel into aspects of cave mining prior to the implementation of a panel retreat cave in the BA5 mining block. This included visits to cave mines using LHD's for extraction in other areas of the world. Problems after initial implementation of the BA5 cave forced further investigations by the Geotechnical Department. Premier Diamond Mine had experienced problems in predicting the area that would need to be undercut to induce continuous caving in caves above the gabbro siII. D.H. Laubscher's correlation of Mining Rock Mass Rating with hydraulic radius was found to be the most accurate method of predicting the area that needs to be undercut to induce continuous caving. An expert system to predict the fragmentation that will result as ore caves and moves through the draw coIumn to drawpoints below was developed and successfully calibrated at Premier Diamond Mine. Prediction of the fragmentation size distribution and hangup frequency have been used to plan several aspects of cave mining.
The effect of shear stresses on pillar strength
(University of Pretoria, 2015) Malan, D.F.; Napier, J.A.L.; jannie.maritz@up.ac.za; Maritz, Jan Abram
In mining, the loading environment on pillars is highly complex with combinations of normal and shear stresses. It is also understood that with an active and working face, constant redistribution of stresses will occur to maintain stress equilibrium. A rock sample subjected to uniaxial loading conditions can fail in either indirect tension or shear. A pillar in the mining environment would react in much the same way. However, as “confinement” is created at the pillar and hanging wall or footwall contacts, shear failure is commonly observed in failed pillars. A number of theories and equations have been derived trying to correctly calculate pillar strength in an underground design. These early attempts argued that the strength is only governed by the width of the pillar in relation to the mining height as well as a certain pillar “strength” constant (K-value). Both the coal and hard rock industries have adopted this design methodology for determining pillar sizes, all with relatively good success. Numerical analysis has shown that complex stress interaction occur between irregular shape pillars when not superimposed, highlighting the fact that superimposing of pillars should be treated with caution. As the stress environment changes, so does the loading on the pillar with preliminary results showing that the strength of the pillar will also be affected in the presence of shear stress. The research presented in this document shows that loading conditions that may affect pillar strength should be considered and detailed and special treatment should be given during the design in cases where shear loading may exist.
The Geology of the Rustenburg Fault
(University of Pretoria, 1997) Eriksson, Patrick George; Bumby, Adam John
The N.N.W.-S.S.E. striking Rustenburg Fault zone, in the western Transvaal Basin, South Africa, has been mapped, in order to unravel its tectonic history. Thickness differences in the Daspoort Formation of the Pretoria Group on opposite sides of the Fault suggest that the Fault was active during Pretoria Group sedimentation, with normal faulting producing localised second-order basins on the down-thrown side of the Fault. In post-Pretoria Group times, but before the intrusion of the Bushveld Complex at -2050 Ma, the area surrounding the Fault zone underwent two compressive events. The first was directed N.E.S. W., producing S.E.-N.W. trending folds, and the second was directed N.W.-S.E., producing N.E.-S.W. trending folds. The second set of folds refolded the first set to form typical transitional Type 1-Type 2 interference folding, and this compression ultimately caused reactivation of the Rustenburg Fault, so that dextral strike-slip movement displaced the Pretoria Group sediments by up to 10.6 km. The subsequent intrusion of the Bushveld Complex into the adjacent strata intensely recrystallised, and often assimilated, the strata along the Fault zone. The fault rocks within the Fault zone were also recrystallised, destroying any pre-existing tectonic fabric. Locally, the Fault zone has been assimilated by the Bushveld Complex. After the intrusion of the Bushveld Complex, little movement has occurred along the Fault, especially where the Fault passes under areas occupied by the Bushveld Complex. It is thought that the crystallisation of the Bushveld Complex has rheologically strengthened the neighbouring strata, preventing them from being refaulted. This model presented above is at variance with previous assumptions that continuous regional extension during Pretoria Group sedimentation culminated in the intrusion of the Bushveld Complex.

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