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

A dissertation submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, for the Degree of Master of Science. / storage and waste dumps from coal mining tend to spontaneously combust. This is mainly as a result of the oxidation process which is accelerated by the availability of oxygen and the exothermic nature of the oxidation process. In cases of poor ventilation the heat accumulation within the bed is thought to lead to the spontaneous combustion of coal. The work in this dissertation aims to investigate the change in oxygen concentration in a bed of coal and also measure the rate of oxidation (oxygen absorption) in a closed reactor under isothermal conditions. Drying rate of coal under nitrogen was also looked into. An analysis of the oxygen concentration profile in a three metre 20 cm ID plastic column filled up with coal has been carried out. As the coal ages (becomes oxidised) its reactivity towards oxygen decreases and changes in the oxygen concentration profile are noticed. Experiments have been carried out up to 8 months and from the results obtained, a simple pseudo-steady-state model has been developed to describe the diffusion of oxygen into a reacting coal bed. The findings could prove useful in trying to find a solution to coal and waste dump fire control. The second experiment is a simple isothermal oxygen absorption experiment in which the rate of absorption of oxygen on a given coal sample is measured at different initial concentrations of oxygen. The initial concentration of oxygen is varied over a fairly wide range in order to determine the dependence of the rate of oxidation on the oxygen concentration. The rate- limiting step in low temperature oxidation of coal is found to be the absorption of oxygen. Moisture also plays a role in coal oxidation. Drying experiments were also carried out so as to quantify and investigate the rate of loss of moisture. Models have been developed which try to explain the mechanisms involved in the drying process. The modelling suggest that the bound water model is more appropriate to the type of behaviour exhibited during the drying process / Andrew Chakane 2018

A dissertation submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, for the Degree of Master of Science. / Storage and waste dumps from coal mining tend to spontaneously combust. This is mainly as a result of the oxidation process which is accelerated by the availability of oxygen and the exothermic nature of the oxidation process. In cases of poor ventilation the heat accumulation within the bed is thought to lead to the spontaneous combustion of coal. The work in this dissertation aims to investigate the change in oxygen concentration in a bed of coal and also measure the rate of oxidation (oxygen absorption) in a closed reactor under isothermal conditions. Drying rate of coal under nitrogen was also looked into. An analysis of the oxygen concentration profile in a three metre 20 cm ID plastic column filled up with coal has been carried out. As the coal ages (becomes oxidised) its reactivity towards oxygen decreases and changes in the oxygen concentration profile are noticed. Experiments have been carried out up to 8 months and from the results obtained, a simple pseudo-steady-state model has been developed to describe the diffusion of oxygen into a reacting coal bed. The findings could prove useful in trying to find a solution to coal and waste dump fire control. The second experiment is a simple isothermal oxygen absorption experiment in which the rate of absorption of oxygen on a given coal sample is measured at different initial concentrations of oxygen. The initial concentration of oxygen is varied over a fairly wide range in order to determine the dependence of the rate of oxidation on the oxygen concentration. The rate- limiting step in low temperature oxidation of coal is found to be the absorption of oxygen. Moisture also plays a role in coal oxidation. Drying experiments were also carried out so as to quantify and investigate the rate of loss of moisture. Models have been developed which try to explain tile mechanisms involved in the drying process. The modelling suggest that the bound water model is more appropriate to the type of behaviour exhibited during the drying process. / Andrew Chakane 2018

No description available.

Mining of the Basal Reef at Jeanette Mine, is typically complicated due to an overlaying Khaki Shale (shale) that has unfavourable rock engineering properties. Shale has always been either left underground or mined as part of the orebody. The first approach can only be applied in areas where the quartzite beam (directly above the Basal Reef and below the shale) is of sufficient thickness to support the shale in the hanging wall. This method is known as undercutting. Alternatively, open stoping can be applied in areas where the shale and the Basal Reef is extracted concurrently and sent to the mill as diluted ore. Alternatively, a resue stoping method can be considered in areas where undercutting cannot be done, due to a thin quartzite middling. Resue stoping involves stowing or packing of the shale into the mined-out area and is not included as part of the hoisted rock. In the past, resue stoping was done by hand packing, which is unsuitable for a modern mine. As such, two mechanised resue stoping methods can be considered, namely; Longhole Resue Stoping and Rib Cutting Resue Stoping. Rib Cutting Resue Stoping utilises a continuous miner (“CM”) to remove the shale in a first pass, extract the reef during a second pass and backfilling the mined-out rib with shale. The use of a CM will significantly improve the extraction/mining rate, sidewall stability, backfill placement, dilution and overall safety. Longhole Resue Stoping utilises strike drives from where longholes are drilled into the shale and the reef in an up-dip direction moving on retreat. The shale is blasted with sufficient force into the mined-out area behind it, compacting it. The reef will be loaded by Load Haul Dumper (“LHD”) or dozer. It was determined that Rib Cutting Resue Stoping is more effective than Longhole Resue Stoping due to a higher extraction rate, lower dilution, reef loss reduction and improved shale sidewall stability. The operating angles and equipment height limits the application to only 51% of the available reef at Jeanette mine with favourable dip and thickness. Longhole Stoping can navigate hard rock, shale and increased dip angles; it can be applied to 91% of the available ore deposit. Longhole Resue Stoping and Rib Cutting Resue Stoping should both be considered as suitable stoping methods for Jeanette. / Thesis is submitted in partial fulfilment for the degree of Master of Science in Engineering to the Faculty of Engineering and the Built Environment, School of Mining Engineering, 2018 / XL2019

Introduction It is well established that gold mine dust is a major cause of pneumoconiosis and other lung diseases. The main sources of dust in gold mines are well documented. Rock drill operators using pneumatic percussion rock drills are at the sharp end of exposure due to the very nature of the drilling process in that rock is pulverized and liberate large amounts of dust even with the addition of copious amounts of water. Historically it has been found that the gold bearing rock formations in South Africa typically contain about 30% quartz. (1) Keeping this in mind, the potential for overexposure is obvious. The actual exposure of rock drill operators to dust and quartz is not well documented and for this reason this research focuses on this particular occupation. Objectives To measure the respirable dust and quartz exposure of Rock Drill Operators in two typical gold mines in the Free State province of South Africa in 2007. Methods This study is a descriptive, cross sectional, rapid assessment based on the findings of gravimetric sampling results taken at Rock Drill Operators working underground on two different gold mines. The actual gravimetric sampling was done in accordance with NIOSH methodology. The study population consisted of 30 Rock Drillers on one mine and another 30 on a second mine. The Rock Drill Operators was randomly selected using their company numbers and selected by the “Excel” program random number selection function. Ordinary gravimetric sampling, using Gillair pumps, was used and weighing done on the mine by a qualified and well experienced Air Quality Analyst using an appropriate methodology compatible with international best practices. Quartz analysis was done at the National Institute for Occupational Health (NIOH) in Johannesburg using a Phillips X-Ray diffraction. (Photo 2). The methodology used by the laboratory technician is conducted strictly according to the manufacturer’s specifications and in line with international best 5 practices. This laboratory participates in quality assurances programmes and is highly regarded internationally. Results The initial hypothesis that exposure underestimation in the past in terms of this particular occupation is confirmed and could be contributable to the difficulties typically experienced when using the traditional gravimetric sampling method. The average quartz percentage was determined to be 25.45% for mine 1 and 38.49% for mine 2 giving an average of 30.67% for both mines. The Total Mass means was 0.73 and 0.23 mg for mine 1 and 2 respectively with an average for the two mines being 0.49 mg. Results for Time Weighted Averages revealed values of 0.69 and 0.22 mg/m3 for mine 1 and 2 respectively with an average of 0.46 mg/m3 for both. In terms of Air Quality Index (AQI) the values were 1.4 and 0.6 for mine 1 and 2 respectively with an average for both mines therefore being 1.1. A comparison with the South African OEL for quartz showed overexposure on 32% of all rock drill operators sampled. When using the NIOSH OEL that figure is even worse at 72%. Based on these results it would thus be fair to conclude that Rock drill operators working without appropriate respiratory equipment will be overexposed and therefore potentially suffer ill health as a result. Discussion and conclusion Rock drill operators are potentially exposed to high levels of harmful dust and quartz in their normal daily work if not adequately protected using good, effective appropriate and comfortable respiratory protective equipment (RPE) and additionally having proper ventilating velocity. At an average Air Quality Index (AQI) of 1.1, it would require the mine Occupational Hygienist to immediately institute remedial action in conjunction with an investigation to determine the reasons for such overexposure. The AQI of 1.46 and 0.6 for Mine 1 and 2 respectively curiously beg the question as to why there is a difference. The answer unfortunately is not clear at first glance as both mines wetted the stope working faces equally well, ventilates the faces with similar velocities which in turn alludes to similar dilution factors but the only reasonable deduction that could be made is that high TWA respirable quartz pollutant concentrations (mg/m3) values in lots of cases corresponded with low actual quartz values. This could be co-incidental but in fact caused the TWA graph to be inversely proportional to the AQI graph. Couple this to the fact that the actual dust burden is lower in Mine 2 compared to Mine 1 as confirmed by the TWA values obtained, then the results becomes easier to interpret. However, the assumption is made that the TWA values should enjoy more preference in the analytical sense as it could be compared directly to OEL’s which serves to highlight the hypothesis very clear in that rock drill operators are over exposed to a high degree of certainty which in turn concurs with other research done in the past. The fact that the methods used to drill holes in order to be charged up with explosives has largely remained unchanged for more decades in the mining industry with no viable alternative on the horizon, emphasizes the fact that focused attention and proper risk assessment is called for to protect rock drill operator from harmful exposure. That said the normal paper dust mask cannot in all good conscience be regarded as appropriate RPE for this occupation. The aforementioned risk assessment must determine and ultimately classify which occupations would benefit from “upgrading” to better quality dust masks. To accept only one type of dust mask on a mine would be considered a travesty and contrary to the application of all good occupational hygiene principles. Failing to expedite the aforementioned risk assessment on RPE per occupation will result in failure to place effective safeguard measures in place to protect rock drill operators from harmful dust and will mean that their health will be compromised in time. The development of air line fed type hard hats incorporating a face shield, harness fitted with moisture trap, filter and a snap fit attachment to a compressed air line is likely to be the ultimate solution provided that it is light, comfortable and the introduction is done in a manner that will ensure the understanding in the benefits to be derived from using such a device in the place of ordinary dust masks by Rock 7 Drill Operators. Ultimately, using the Occupational Hygiene hierarchy of control that dictates the first consideration of such control being elimination, coupled with the horrendous ergonomic problems faced by rock drill operators, the solution seems to point inevitably towards meganisation. Using a person in the same homogeneous exposure group (HEG) as that of the rock drill operator as a forced alternative is not advisable as the exposure of a rock drill operator is very unique and certainly not comparable to that of a winch driver for example. The wet environment certainly warrants the investigation into alternative methods for sampling as normal, traditional methods proved to be inconsistent, unreliable and often unusable.