3. Electronic Theses and Dissertations (ETDs) - All submissions
Permanent URI for this communityhttps://wiredspace.wits.ac.za/handle/10539/45
Browse
6 results
Search Results
Item Mining's contested future :employee and community participation in South Africa's mining charters(2019) Du Plessis, Gideon EdwardThis research report examines a multi-stakeholder attempt by the Department of Mineral Resources (DMR) to introduce a range of institutional structures to ensure meaningful participation in the transformation of the mining industry. The majority of South Africans were systematically marginalised and thus prevented from meaningful participation and ownership in the mining sector through colonial rule and the exclusionary policies of apartheid. To redress these historical inequalities, the DMR developed the Minerals and Petroleum Resources Development Act (28 of 2002) (MPRDA) and the Broad-Based Black Economic Empowerment Charter for the South African Mining and Minerals Industry ("Mining Charter") as a regulatory instrument in 2004. To increase employee participation and development of the mining community, the Act introduced compulsory future forums and social and labour plans to complement the objectives of the Mining Charter. The latter was developed with specific measurable targets in mind to effect transformation of the industry. The Department of Mineral Resources and Energy1 (DMRE) conducted a comprehensive assessment of the progress of transformation in the mining industry in 2009 and measured it against the objectives and agreed targets contained in the Mining Charter (Department of Mineral Resources, 2004). The identified shortcomings resulted in the publication of a revised charter in 2010. A further assessment, conducted in 2015, identified shortcomings in the implementation of the various elements of the revised charter. Against this backdrop, the DMR initiated a process to review the Charter with the intention to further strengthen the Mining Charter as a tool for effecting meaningful broad-based transformation of the mining and minerals industry. The initial review process, which commenced in 2016, was a failure in terms of social partner participation and subsequently, a second (and more inclusive) review process was enacted in 2018. This report investigates the process of constructing the Mining Charter (Mining Charter III, 2018) and assesses the extent to which meaningful participation (decision-making and financial terms) has been introduced in the mining sector by means of the revised Charter. At the time of the negotiations, the department was called the Department of Mineral Resources (DMR) – which was changed to the Department of Mineral Resources and Energy (DMRE) in June 2019. DMR and DMRE will be used interchangeably depending on the context. Past attempts at the institutional transfer of the German co-determination system in South Africa failed because they did not account for South Africa’s distinct industrial relations traditions and the socio-economic context. The researcher demonstrates how the clause providing for employee and community representation on company boards was removed from the final Charter and why the innovative attempt to include the “community” in charter consultations failed to gain support. On the positive side, the failed employee share ownership plans (ESOPs) will be replaced with an employee ownership and shareholding scheme provided for in the new charter, where mining employees will receive 5% carried interest shares, at no cost to the employee. This report also discusses the social partners’ responses to the abovementioned provision. Mine communities will furthermore become the beneficiaries of 5% carried interest shares or enjoy the equity equivalent thereof. Furthermore, a trust is to be established to strengthen social and labour plans with community and company representatives that will jointly identify and implement projects. This means that mining communities will receive a formal avenue to influence decision-making about development projects. Despite the attempt to increase ownership and meaningful participation through the new Charter, the challenges of transformation in the South African mining sector go well beyond traditional notions of employee participation and community development. There is also the migrant labour system, a legacy of discriminatory laws that disrupted communities and family life, but also created the dynamic of “us” and “them” between host communities and communities from labour-sending areas. The research report also focuses on the types of complexities adding to the mining industry’s contested future.Item Reducing risks due to rockbursts: strategic financial considerations(2018) Moganedi, Kadibetjo AdelaideGold mines in the Far West Witwatersrand area experience frequent mining induced seismic events due to dynamic stress changes associated with the depth and extent of mining. Some of these seismic events result in rockbursts, of varying magnitudes, in access tunnels. Geological structures, mine design layout and support system design influence the magnitude of a rockburst damage in an underground excavation. Support systems are the last line of defence and are effective in environments where the mining layout is optimised for dynamic stress changes. The objective of this research is to determine the financial value energy absorbing support systems add to a rockburst prone well designed mine. The research focuses on quantifying indirect consequences of rockburst risk using an Excel model developed as part of this research. The model has three versions, each targeting a specific user. The model is used to evaluate the financial benefits of different support systems in access tunnels prone to seismicity and possible rockbursts. Executive management can use the Executive spreadsheet of the model to facilitate proactive rockburst risk management. Four case studies were evaluated in detail, and the results indicate production loss is the major source of quantifiable financial loss after a rockburst. The tunnels were supported with variations of rigid support systems, even though energy-absorbing support systems were the most suitable for dynamic loading conditions, and were likely to have contained the rockburst events. This is because energy-absorbing support systems are viewed as an unnecessary expense. However, the “extra” cost of energy absorbing support system, as a strategy to minimise effects of rockbursts, will almost always create better value than the less expensive rigid support. This extra cost can be significantly reduced by increasing the spacing between yielding tendons in an energy absorbing support system. In conclusion, it is strategic for rockburst prone mines to install high quality yielding support systems as they have the potential to create substantial long term value for the mine.Item Towards sustainable economic development in the gold mining areas of South Africa and Ghana(2017) Boaduo, Adwoa PokuaaIn many mineral resource rich African countries, mining activity makes a significant contribution towards the Gross Domestic Product (GDP) and economic growth. This stimulus gives the mining industry the potential to fuel growth and development. Although some mining areas have been able to experience positive economic growth, many have struggled to achieve and sustain economic development due to the inability to manage mineral wealth challenges. African mining regulatory bodies generally lack proper local planning, resulting in inadequate policy instruments to enable the sector to make a sustainable contribution towards economic welfare. This research investigates how mineral wealth can be used as a catalyst for sustainable economic development. The research presents the case studies of three mining areas with the aim of determining why the economic development of Johannesburg differs substantially from that of Tarkwa and Obuasi. The research gives a comparative analysis of the political economy and socio-economic trends that have transpired in the three areas over the years. It ends by making recommendations on how Tarkwa and Obuasi can better manage the challenges of mineral wealth, and work towards achieving sustainable economic development that is like or even better than that of JohannesburgItem Finding the optimal dynamic anisotropy resolution for grade estimation improvement at Driefontein Gold Mine, South Africa(2016) Mandava, Senzeni MaggieMineral Resource estimation provides an assessment of the quantity, quality, shape and grade distribution of a mineralised deposit. The resource estimation process involves; the assessment of data available, creation of geological and/or grade models for the deposit, statistical and geostatistical analyses of the data, as well as determination of the appropriate grade interpolation methods. In the grade estimation process, grades are interpolated/extrapolated into a two or three – dimensional resource block model of a deposit. The process uses a search volume ellipsoid, centred on each block, to select samples used for estimation. Traditionally, a global orientated search ellipsoid is used during the estimation process. An improvement in the estimation process can be achieved if the direction and continuity of mineralisation is acknowledged by aligning the search ellipsoid accordingly. The misalignment of the search ellipsoid by just a few degrees can impact the estimation results. Representing grade continuity in undulating and folded structures can be a challenge to correct grade estimation. One solution to this problem is to apply the method of Dynamic Anisotropy in the estimation process. This method allows for the anisotropy rotation angles defining the search ellipsoid and variogram model, to directly follow the trend of the mineralisation for each cell within a block model. This research report will describe the application of Dynamic Anisotropy to a slightly undulating area which lies on a gently folded limb of a syncline at Driefontein gold mine and where Ordinary Kriging is used as the method of estimation. In addition, the optimal Dynamic Anisotropy resolution that will provide an improvement in grade estimates will be determined. This will be achieved by executing the estimation process on various block model grid sizes. The geostatistical literature research carried out for this research report highlights the importance of Dynamic Anisotropy in resource estimation. Through the application and analysis on a real-life dataset, this research report will put theories and opinions about Dynamic Anisotropy to the test.Item A pre-feasibility study of the Kloof Eastern Boundary Area project, Kloof Gold Mine(2003) Ghoussias, KonstandinosThe 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.Item Identification of inelastic deformation mechanisms around deep level mining stopes and their application to improvements of mining techniques.(2014-02-26) Kuijpers, J.S.Mining induced fracturing and associated deformations can commonly be observed around deep gold mining excavations. As the rockmass behaviour and the stability of the excavations are directly influenced by these processes, a proper understanding of this influence would certainly improve current mining practices with respect to blasting, rock breaking, support design and mining lay-outs. The main subject of this thesis is the physics of failure and post failure behaviour of rock and similar materials. Failure is denned here as a state at which the material has been subjected to fracture and/or damage processes. The applicability of commonly used constitutive models in representing such failure and post failure processes has been investigated mainly by means of numerical simulations. Mechanisms which control fundamental fracture and damage processes have been analysed by comparing the results from relevant laboratory experiments with numerical models. Linear elastic fracture mechanics has been applied to explain and simulate the formation of large scale extension fractures which form in response to excessive tensile stresses. Using the flaw concept it is demonstrated that these fractures not only initiate and propagate from the surface of an opening in compressed rock, but that so called secondary fracturing can be initiated from within the solid rock as well. The effect of geological discontinuities such as bedding planes, faults and joints on the formation of (extension) fractures has also been investigated and it has been shown how the presence of such discontinuities can cause the formation o f additional fractures. Micro mechanical models have been, used to investigate the interaction and coalescence processes of micro fractures. It was found that the formation of large scale extension fracturing can be explained from such processes, but so called shear fractures could not directly be reproduced, although such a possibility has been claimed by previous researchers. The formation of shear fractures is of particular- interest as violent failure of rock, which is subjected to compressive stresses only, is often associated with such fractures. In an all compressive stress environment, only shear deformations would allow for the relief of excess stress and thus energy. The formation of shear fractures is associated with complex mechanisms and shear fractures can therefore not directly be represented by tingle cracks. In contrast to the propagation of tensile fractures, which can readily be explained by traditional fracture mechanics in terms of stress concentrations around the crack tip, the propagation of shear fractures requires a different explanation. In this thesis an attempt has nevertheless been made to reproduce shear fractures by direct application of fracture mechanics. This his been done by representing a shear fracture as a single crack and by assuming fracture growth criteria which are either based on critical excess shear stresses, or on a maximum energy release. Both criteria are completely empirical and require a value for the critical shear resistance in the same way as a critical tensile resistance is required to represent the formation of tensile fracture; , The determination of a critical tensile resistance ( Kk ) is relatively straight forward, as the formation of tensile fractures from a pre-existing flaw can be reproduced and observed in standard laboratory tests. The determination of a critical shear resistance is, however, not a common practice, as the formation of a shear fracture from a pre-existing flaw is very infrequently observed. The application of shear fracture growth criteria nevertheless resulted in plausible fracture patterns, which suggests that such criteria are realistic. It is argued here however that the formation of shear fractures cannot be associated with primary fracture growth, but rather with the localisation of failure and damage in an area which is subjected to plastic deformation. The application of fracture mechanics is therefore not correct from a fundamental point of view as these processes are not represented. For this reason plasticity theory has also been applied in order to simulate failure in general, and shear failure localisation in particular. It was in principle possible to reproduce the shear fractures with the use of this theory, but numerical restraints affected the results to such an extent that most of the simulations were not realistic. Plasticity theory can also be extended to include brittle behaviour by the use of so called strain softening models. The physical processes which lead to brittle failure are however not directly represented by such models and they may therefore not result in realistic failure patterns. It was in fact found that strain softening models could only produce realistic results if localisation of failure could be prevented. The effect of numerical restraints becomes even more obvious with a strain softening model in the case of failure localisation. While the plasticity models appear inappropriate in representing brittle failure, they demonstrated that plastic deformations can be associated with stress changes which may lead to subsequent brittle fracturing. Although only indirect attempts have been made to reproduce this effect, as appropriate numerical tools are not available, it is clear that many observations of extension fracturing could be explained by plastic deformations preceding the brittle fracturing processes. Many rocks are classified as brittle, but plastic deformation processes often occur during the damage processes as well. The sliding crack for instance, which is thought to represent many micro mechanical deformation processes in rock, directly induces plastic deformations when activated. A pure brittle rock, which may be defined as a rock in which absolutely no plastic deformation processes take place, may therefore only be of academic interest as it is inconceivable that such a rock materiel exists. Only in such an academic case would (linear) elastic fracture mechanics be directly applicable. As plastic deformation processes do play a role in real rock materials it is important to investigate their influence on subsequent brittle failure processes. The elastic stress distribution, which is often used to explain the onset of brittle fracturing, may be misleading as plastic deformations can substantially affect the stress distribution . -recediny fracture initiation. In an attempt to combine both plastic and brittle failure, use has been made of tessellation models, which in effect define potential fracture paths in a random mesh. The advantage of these models is that various failure criteria, with or without strain softening potential, can be used without the numerical restraints which are normally associated with the conventional continuum models. The results of these models are also not free from numerical artefacts, but they appear to be more realistic in general. One o f the m;ij, r conclusions based on these results is that shear failure does not occur in a localised fashion, but is associated with the uniform distribution and extension of damage. Shear failure, which can be related directly to plastic failure, can however induce brittle, tensile, failure due to stress redistribution. While the theories of fracture mechanics and plasticity are well established, their application to rock mechanical problems often leads to unrealistic results. Commonly observed firacture patterns in rock, loaded in compression, are most often not properly reproduced by numerical models for a combination of reasons. Either a model concentrates on the discrete fracturing processes, in which case the plastic deformation processes are ignored, or plasticity is represented, but brittle failure is pooxiy catered for. While theoretically a combination of these models might lead to better representations and simulations, numerical problems do affect all models to a certain extent and a practical solution is not immediately available. The results of numerical models can therefore only be analysed with caution and the underlying assumptions and numerical problems associated with a particular technique need to be appreciated before such results can be interpreted with any sense. Many of the problems are identified here and this may assist researchers in the interpretation of results from numerical simulations. Laboratory experiments, which have been chosen for analyses, involve specimens which have been subjected to compressive stresses and which contain openings from which failure and fracturing is initiated. Such specimens are less subjective to boundary influences and are far more representative of conditions around mining excavations than typical uni- and tri-axial tests. The uniform stress conditions in these latter tests allow boundary effects to dominate the stress concentrations, and thus failure initiation, in the specimens. The large stress gradients, which can be expected to occur around underground excavations, are not reproduced in such specimens. As a consequence failure is not u atained within a particular area, but spreads throughout the complete specimen in the uni- and tri-axial tests. Specimens containing openings are therefore far more likely to reproduce the fracture patterns which can be observed around deep level mining excavations. Numerical simulations of brittle, tensile fracturing around mining excavations resulted in consistent fracture patterns. Fracture patterns could however be strongly influenced by the presence of geological (pre-existing) discontinuities such as bedding planes. Although tensile stresses are often assumed to be absent around deej: