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A thesis submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2016 / The blind headings created in room and pillar mining are known to be the high risk areas of the coal mine, since this is where the coal production is actually taking place and hence the liberation of maximum quantity of methane. The ventilation of this region called the localized ventilation is carried out using auxiliary ventilation devices. This ventilation may be planned and be the subject of mine standards, but it is not very well understood and implementation on a day to day basis is usually left to the first level of supervisory staff. Majority of the methane explosions have been found to occur in these working areas and blind headings. The correct use of auxiliary ventilation devices can only be carried out once the effect of the system variables associated with each device is very well understood and can be calculated mathematically. Presently, no mathematical models or empirical formulas exist to estimate the effect of the associated system variables on the flow rates close to the face of the heading. The extent of ventilation of a heading ventilated without the use of any auxiliary device is not clear. Furthermore, to design additional engineering solutions, the flow patterns inside these heading ventilated with the auxiliary ventilation devices needs to be understood. The study of the face ventilation systems and the effect of the system variables associated system with each auxiliary ventilation device can be carried out experimentally, but doing a large number of experiments underground is very difficult as it disturbs the mine production cycles. Furthermore, studying the flow patterns experimentally is even more cumbersome, and can only be done to some extent using smoke or tracer gas. Therefore, Computational Fluid Dynamic‟s (CFD) advanced numerical code ANSYS Fluent was used to study the effect of a number of system variables associated with the face ventilation systems used in blind headings. As part of the procedure, the CFD model used was validated using four validation studies, in which the numerical results were compared with the actual experimental results. The numerical results differed to a maximum of 10% for all the experimental results. The system variables associated with ventilation of a heading, without the use of any auxiliary device, with the use of Line Brattice (LB) and fan with duct were selected. A range of values was chosen for each variable, and scenarios were created using every possible combination of these variables. All the scenarios were simulated in Ansys Fluent, the air flow rates, air velocities, velocity vectors, and velocity contours were calculated and drawn at different locations inside the heading. The effect of each system variable was found using a comparative analysis. The results were represented in simple user-friendly form and can be used to estimate the air flows at the exit of the LB and face of the heading for various settings of the LB and fan and duct face ventilation systems. The analysis of the ventilation of a heading without the use of LB shows that a maximum penetration depth is found with the Last Through Road (LTR) velocity of 1.35m/s. The flow rates and the maximum axial velocities increase with the increase in the LTR velocity up to a depth of 10m (maximum air flowing into a heading of 1.26m3/s and 1.58m3/s is found for the 3m and 4m high heading using 2m/s LTR velocity). For the LB ventilation system the LTR velocities, heading height, length of the LB in the LTR and heading, angle of the LB in LTR, and distance of the LB to the wall of the heading (side wall) were varied to identify clearly the effect of these control variables, on the flow rate at the exit of the LB, and close to the face of the heading. The flow rate at the exit of the LB is found to be proportional to the product of the distance of the LB to the wall in the LTR and heading. The flow rate at the exit of the LB, face of the heading, and inside the heading is found proportional to the LTR velocity and height of the heading. It is found that a minimum length of LB is associated with each distance of the LB to the wall in the heading, to maximize the delivery of air close to the face of the heading. This length is found to be equal to 15m for 1m LB to wall distance, and 10m for 0.5m LB to wall distance. Mathematical models were developed to estimate the effect of each studied system variables on the flow rates at the exit of the LB and close to face of the heading. For the fan and duct systems the length, diameter, and the fan design flow rates were varied. It is found that for a force fan duct system only a maximum of 50% of the total air that reaches the face is fresh and the remaining 50% is recirculated air. The flow rate with the exhaust fan system is found to be much lower than the force fan duct system. It increases with the reduction in duct mouth to heading face distance, and increase in duct diameter. Mathematical models are developed to calculate the flow rates at the face of the heading using the effect of each studied system variable. The research reveals that the ANSYS numerical code is an appropriate tool to evaluate the face ventilation of a heading in a three dimensional environment using full scale models. The South African coal mining industry can benefit from the outcomes of this study, specially the mathematical models, in a number of ways. Ventilation engineers can now estimate the flow rates close to the face of the heading for different practical mining scenarios and ensure sufficient ventilation by using the appropriate auxiliary ventilation settings. The results can easily be developed into training aids using easy to use excel spread sheets to ensure that mineworkers at the coal face have a better understanding of the working of the auxiliary ventilation devices. It can also serve Academia as part of the curriculum to teach the future mining engineers how the different variables associated with the auxiliary ventilation system affect the ventilation in a heading. The research therefore, has the potential to provide a significant step toward, understanding airflow rates delivered by the auxiliary devices close to the face of the heading and the air flow patterns inside the heading as a basis for improving the working environment for underground mineworkers. / MT2017

Thesis (M.Sc. (Engineering))--University of the Witwatersrand, Faculty of Engineering, 1987.

A dissertation submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in fulfilment of the requir tents for the degree of Master of Science in Engineering. Johannesburg 1996. / The design of bord and pillar working in South African collieries is based on the pillar strength formula developed by Salamon and Munro1967 and which has been used widely since then for designing pillars. This formula is based on the statistical analysis of 27 collapsed and 98 intact coal pillar cases from collieries located in the Transvaal and the Free state. The main objective of this study is to establish the difference in the strength of the coal material in ditferent seams by means of laboratory testing. In this manner, some 753 coal samples from 10 collieries from 4 seams were tested. The size and width to height ratio effects on strength were analysed. The size effect showed that the difference between the seams was obvious, with a difference of 59,4 per cent between the strongest and weakest coal. The statistical re-analysis showed that the strength of the six blocks from the No 2 seam, Witbank Coalfield occurred in a fairly tight strength range; and that laboratory coal strengths from individual seams or mines could deviate to a significant although relatively small extent from the overall average. / AC2017

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Scieuce in Geophysics . / Rockbursts continue to be one of the more high profile and problematic worker hazards in the South African gold mining industry. Recent advances in the technology of seismic monitoring systems and seismic data analysis and interpretation methods hold considerable promise towards improving the success rate of rockburst control measures. This study tests different methods for the evaluation of the response of geological structures to mining induced stress changes. A small part of Western Holdings Gold Mine in the Welkom goldfield -- the Postma Area -- offers a challenge because of its geological complexity, accessibility and high incidence of seismicity. The sensitivity of the local network to ground motions in this area of interest and the expected spatial location accuracy is established and deemed adequate for a detailed investigation of seismic activity. The local mining geometry, geology and methods of mining are discussed. The fractured state of the rock mass observed in situ, close to the stope faces, is in agreement with the results of numerical elastic modelling and the high stresses inferred seismically. Almost immediately after the incidence of a large event (ML 3.7) which occurred close to one end of a dyke, an increased rate of seismic activity became apparent at another part of the same dyke, some 250 m to the east. A change in the state of seismic stress, before and after the large event, points to a transfer of stress along this geological discontinuity. A quantitative analysis of recorded seismicity indicates spatial and temporal variations in the state of stress and strain throughout the rock mass surrounding Mining excavations. The elastic stress modelling performed routinely by rock mechanics engineers in the deep gold mines is, by itself, incapable of catering for the rheological nature of the rock mass, but taken together with independent seismic evaluations of a fault orthogonal to a highly stressed dyke it is shown that both methods are mutually complementary and can enhance the assessment of the seismic instability of the structures. A back-analysis is conducted on ten large seismic events (ML> 2.5) to identify precursors. These show that the timely recognition of high gradients in physical seismic parameters pertaining to strain rate and stress in time and space immediately prior to major seismic events is a real and practical possibility, as such constituting an early warning mechanism. The fore-warning of a large event is best served by an analysis of seismicity over the short term (weeks or days) through time-history variations and/or contouring of various seismic parameters, although long-term seismic responses (months or weeks) characterise specific patterns and trends which are useful in the forecast. / AC2018

A thesis submitted to the School of Animal, Plant and Environmental Sciences (APES), University of the Witwatersrand, Johannesburg, South Africa in fulfilment of the academic requirements for the degree of Doctor of Philosophy Johannesburg, February 2013 / Decades after the commencement of modern mining in the 1870s, the South African mining industry addressed the impacts associated with its mine waste deposits. In this, it followed the pattern its international peers had set. This study aims at chronicling, for the first time, the mining industry’s efforts to develop scientifically sound and replicable methods of mine waste rehabilitation. Mindful of the limitations in accessing official and public written sources for such an applied science, the study seeks to take a broader approach: It considers factors beyond pure experimental results (of which only patchy records exist), and considers the socio-economic context or the role of certain personalities, in an effort to understand the evolution of the applied technology between the 1930s until the passage of the Minerals Act in 1991. The bulk of this mine waste rehabilitation work during this period was done by the Chamber of Mines of South Africa and its members, the gold and (later) coal miners. The focus will therefore be on these sectors, although other mining sectors such as platinum will be covered when relevant. Following decades of ad hoc experimentation, concern about impending legal pollution control requirements in the 1950s spurred key gold industry players to get ahead of the curve to head off further regulation. Their individual efforts, primarily aimed at dust suppression, were quickly combined into an industry initiative located within the Chamber of Mines. This initiative became known as the Vegetation Unit. Well resourced and managed by a dynamic leader with horticultural training – William Cook – the Unit conducted large-scale and diverse experiments between 1959 and 1963 to come up with a planting and soil amelioration methodology. The initial results of this work were almost immediately published in an effort to publicise the industry’s efforts, although Cook cautioned that this was not a mature methodology and that continued research was required. The Chamber of Mines, however, was trying to head off pending air quality legislation and in 1964/65, the organisation publicly proclaimed the methodology as mature and ready for widespread application. With this decision, the Unit’s focus shifted to widespread application while its ability to advance the methodology scientifically effectively collapsed in the 1960s and early 1970s. In addition to this shift of focus and resources to application rather than continued refinement, the Unit was constrained by non-technical and non-scientific factors: Key among them was the industry’s implicit belief, and hope, that a walk-away solution had been found. The Unit’s manager Cook stood alone in driving its application and refinement for most of his time in that position. In his day-to-day work, he lacked an industry peer with whom to discuss rehabilitation results and he compounded this isolation through limited interaction with academia until very late in his career. This isolation was amplified by the lack of relevant technical knowledge among the company representatives on the committee tasked with the oversight of the Vegetation Unit: As engineers, all of them lacked not only technical understanding of the botanical and ecological challenge, some even questioned the legitimacy of the Unit’s existence into the 1980s. In addition, the concentration of all rehabilitation efforts in this single entity structurally curtailed the individual mining companies’ interest in the advancement of the methodology, creating a further bottleneck. Indeed, as late as 1973, the key metallurgy handbook covered mine waste rehabilitation only for information purposes, specifically stating that this was the responsibility of the Chamber’s Vegetation Unit alone. To some extent, the presence of a champion within the Chamber – H. Claussen – obscured some of these challenges until the early 1970s. Indeed, the Unit had acquired additional scientific capacity by this stage, which gave it the ability to renew its research and to advance its methodology. That it failed to do so was mainly due to three factors coinciding: the retirement of its internal champion Claussen, a lack of succession planning for Cook, which left the Unit on ‘auto-pilot’ when he retired, and a rising gold price, which turned industry attention away from rehabilitation towards re-treatment of gold dumps. During this period of transition in the mid 1970s, the Chamber’s approach was thus somewhat half-hearted and vulnerable to alternative, potentially cheaper, rehabilitation proposals such as physical surface sealing advanced by Cook’s eventual successor – Fred Cartwright. Though not grounded in any science, Cartwright’s proposal gained ascendance due to his forceful personality as well as the industry’s desire for an alternative to the seemingly open-ended costs associated with the existing rehabilitation methodology. During this time, the Chamber’s structures singularly failed to protect the industry’s long-term interests: The oversight committee for the Vegetation Unit, remained largely staffed by somewhat disinterested engineers, and relied heavily on a single individual to manage the Unit. Not only did the oversight committee passively acquiesce to Cartwright’s virtual destruction of the Unit’s grassing capacity, it also allowed him to stake the Chamber’s reputation with the regulator by championing an unproven technology for about five years. Only Cartwright’s eventual failure to gain regulator approval for his – still un-proven – technique led to a reluctant abandonment by the Chamber in the early 1980s. Cartwright’s departure in 1983 left the Unit (and the industry) without the capacity to address mine waste rehabilitation, at a time when emerging environmental concerns were gaining importance in social and political spheres in South Africa and across the world. The Unit sought, unsuccessfully, to build alliances with nascent rehabilitation practitioners from the University of Potchefstroom. It furthermore failed to build mechanisms for sharing technical rehabilitation knowledge with fellow southern African or international mining chambers, leading to further stagnation of its method. At the same time, up-and-coming South African competitors such as the University of Potchefstroom seized the opportunity to enter the mine waste rehabilitation field as commercial players during the mid 1980s, at a time when the Unit had been reduced to grassing dumps for a single customer, the Department of Minerals and Energy Affairs (DMEA). Using its status as a part of the Chamber of Mines, the Unit gradually regained its position of prominence through the development of industry guidelines for rehabilitation. Yet, it would never again occupy a position of pre-eminence in practical fieldwork, as industry players, academic capacities and commercial players entered the field in the mid-1980s in response to a growing environmental movement worldwide. When the passage of the Minerals Act in 1991 formally enshrined not merely rehabilitation but environmentally responsible mine closure in law, the Unit had been reduced to a prominent but no longer dominant player in this sector. This lack of pre-eminence ultimately caused the Unit to be among the first Chamber entities to be privatised when the Chamber began to restructure. This ended its role as a central driver of applied rehabilitation techniques for the South African mining sector once and for all. As this privatisation coincided with the broader opening up of South Africa’s society and economy after the unbanning of the ANC, there would never again be an entity (commercial or otherwise) that would dominate the rehabilitation sector as the Chamber’s Vegetation Unit had done in its day.

The mining that gave rise to Johannesburg as a city has left in its wake pieces of geologically disturbed, disused, and unusable land. These leftover fragments of landscape carry with them, not only memory of the city’s foundations, but scars of the mining processes that now render them unusable - Not only do these vaguescapes have potential for the memory within them to be unearthed, but they are highly polluted, and seek to be reimagined as productive city spaces. The chosen site, an abandoned piece of mineland with a concealed old mine shaft; on the edge of a highway on the fringe of the CBD, is simultaneously highly visible to the city, but forgotten to it. Its positioning is unique in that it allows for the potential for the extraction of the mine pollutants and site remediation to become a highly visible process. Understanding and uncovering layers and traces of the site as means of understanding what is possible on this highly polluted landscape became an important architectural and design generator. The architecture consolidates and reimagines the fragments of ruin, both physical and ephemeral, contained on the site, and curates the users experience through these forgotten traces. Its programme - a colour plant, which extracts useful metallic colour pigments from the contaminated earth, becomes a visceral reminder of these past traces ;and a recording device for the current consequences of past mining activity. The approach is an almost critical speculation. The age of the picturesque landscape is no more. Our effects on the land have depleted the earth and diseased its rhythms. But these unstable consequences hold possibilities that can be engaged with imaginatively; rather than merely re-mediated. How can architecture engage with this instability? The project accepts the presence of rising acid mine water; and imagines a new reality emerging from it. The project is a comment on our own epoch; one where waste, toxicity and radiation are so rife, that they are now a quiet, sinister backdrop to our world. More than an apocalyptic future, this project deals with a dystopian present. The precarious site conditions pose questions for an architecture which can engage with the instability, and not merely withstand it. The architectural concern is to render visible and intensify a consciousness of these traces, to investigate a palimpsest infrastructure. Colour, like architecture is a link between the conscious and the subconscious. It is a mediator between the realms. It holds possibilities for suggesting and molding atmospheres and perceptions. The architecture negotiates all the realms, concerned with past, present and future. It consolidates and makes apparent the traces but it is also developed with an awareness that it becomes part of these traces. It is an intervention which aims to heighten an awareness of the presence of the past in the life of the city; and also as palimpsest infrastructure; as a recording device for the geological happenings of the earth.

Thesis ((M.Sc.) Engin))--University of the Witwatersrand, Faculty of Engineering & the Built Environment, School of Mining Engineering, 2003. / The ore reserves of the Kloof Sub Vertical Shaft operations are coming to an end and as such, the Eastern Boundary Area mining operations, which will extract the Ventersdorp Contact Reef ("VCR"), must be commissioned to replace the diminishing reserves. Although feasibility studies have been carried out on the eastern portion of the Kloof Gold Mine lease area, none have been undertaken to investigate the potential benefits of including the new mineral rights recently acquired from JCI. This project report is a prefeasibility study into the potential value to Kloof of accessing and extracting the resources of the Eastern Boundary Area. This project report shows, using DCF analysis, that the Eastern Boundary Area has potential to economically generate the additional reserves that will be required to supplement Kloof s diminishing Three Shaft reserves. An NPV and IRR are calculated for the project, the results of which support the commissioning of further investigative work in order to obtain a better understanding of the orebody and to generate results that are more accurate. Despite its popularity, traditional DCF analysis has fundamental shortcomings, as do the commonly associated measures of NPV and IRR. This project report identifies and reviews these shortfalls and comments on methods to overcome these as far as practically possible.

This thesis proposes some new valuation models and procedures for global and local ore reserve estimation. To obtain efficient grade and tonnage estimates for global borehole valuations of new gold mining properties, the appropriate spatial and distributional models for the mineralisation are absolutely essential. [Abbreviated Abstract. Open document to view full version] / GR 2016

Master of Science in Engineering by advanced coursework and research: A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering Johannesburg, 2016 / The mining sector plays a significant role in the economy of Zimbabwe. The mining sector is the second largest contributor to the country’s GDP at over 20%. Zimbabwe as a country is endowed with abundant mineral resources. The top three commodities in terms of estimated resources are iron ore, coal and platinum with resources of 30 billion tonnes, 26 billion tonnes and 2.8 billion tonnes respectively. Zimbabwe’s vast mineral resources and reserves are of strategic importance to the Zimbabwe economy. Coal mining is one of the major economic contributors to the mining industry in Zimbabwe. The purpose of the study is to determine the optimal operational model for Makomo Resources from a mining and processing point of view. The study is based on a coal-mining project in the Zimbabwean mining industry. Makomo Resources is the largest privately owned coal mining company in the country, which has a mining licence to perform coal-mining activities in the north-west part of the Bulawayo Mining District of Zimbabwe. Makomo Resources applies a conventional strip mining method by means of truck and shovel to extract the coal reserves. Makomo Resources is supplying over 200,000 tonnes of coal per month to the local and export market. The mine has invested in USD20 million capital to commission a wash plant. The study investigates how to optimise the plant throughput by comparing two mining options: Mining Option 1 - crush and screen 2m power coal, crush & screen and wash a full 7m low ash coal seam and wash 2m of coking coal. Mining Option 2 – crush and screen 2m power coal, crush & screen a 3m low sulphur coal seam and wash low ash coal and coking coal of 4m and 2m respectively. The study investigated all the marketing, geology, mining and financial parameters in the Zimbabwean coal mining context. The study determines the appropriate mining methodology and explore to optimise the coal processing. Two financial models were developed to evaluate and compare the two proposed mining options, determine their feasibility and conclude the optimal mining model. Financial techniques were used to analyse and evaluate the two mining options. The financial models were used to analyse and evaluate the following:  The cashflow over the 10-year period.  The Net Present Value (NPV) and Internal Rate of Return (IRR) of each mining option.  The payback period of the washing plant.  Profitability Index per mining option. The NPV of a project determines the economic value of the mining project. The decision on a mining investment is mostly related to the NPV and IRR of the project. Discounted Cash flow (DCF) models were developed for both mining options that shows project cash in and out flows and calculates economic indicators, such as IRR and NPV. The NPV and IRR were the main methods for the evaluation of the two mining options. The resulting DCF models were developed in an Excel spreadsheet format designed for a 10-year Life of Mine (LOM) period. Mining Option 1 has a higher NPV of USD38.2 million in comparison to USD9.7 million for Mining Option 2. The IRR for Mining Option 1 was calculated at 48%, which is bigger than the IRR for Mining Option 2 of 26%. Mining Option 1 has a simple payback period and discounted payback period of 2.7 years and 4.9 years respectively. Mining Option 2 has a simple payback period and discounted payback period of 3.9 years and 11.9 years respectively. Mining Option 1 has a shorter payback period than Mining Option 2. Both mining options have a Profitability Index (PI bigger than one with Mining Option 1 and Mining Option 2 recording values of 1.87 and 1.18 respectively. Mining Option 1 has the better PI value and is therefore more profitable. Based on the economic evaluation, Mining Options 1 is by far more attractive than Mining Option 2, which results in a better return on the investment and profitability, therefore the preferred option. / MT2017