A research report submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Environmental Science Johannesburg, November 2012. / Acid rock drainage (ARD) and dust are potential consequences of gold and uranium mine residue deposits (MRDs) on the Witwatersrand basin. Urbanisation has taken place around mines and, with the curtailing of mining activities and clearing of land previously covered by MRDs, there is pressure to use this land for residential, industrial and agricultural purposes. However, mining companies historically were not required to provide pollution control measures and there is evidence for contamination of land and water. Thus, there is a need to prioritise contamination sources for mitigation and to understand the extent of contamination and potential risks associated with different categories of land-use on mining land. The aim of my study was to conduct a first-order risk assessment to aid in identifying vulnerable land use in the vicinity of gold and uranium mining, and prioritising MRDs, including footprints, for mitigation. To achieve this I constructed a Geographical Information System (GIS) using publicly available spatial data, and then tested the usefulness of historical aerial photographs and remote sensing imagery for mapping MRDs and impacts of MRD origin under Highveld conditions (i.e. a seasonal climate with summer rainfall and annual evapotranspiration of >2.5 times mean annual precipitation). The Ekurhuleni Metropolitan Municipality (EMM; 1923 km2) is an area of extensive historical mining with major urbanisation, while retaining areas for agricultural land use; thus it was selected as a representative study site. I used a numerical rating scheme, which combined a number of parameters in two separate stages to calculate a risk index. The first stage involved the classification of hazards associated with MRDs while the second involved an assessment of land use vulnerability based on exposure pathways and proximity. Historical aerial photographs (1938, 1964 and 2003) and the Chamber of Mines (CoM) Dump Indexes were used to identify and classify MRDs in terms of basic geotechnical properties, current status and historical failure. Multi-spectral data, acquired over two years (2002 and 2003) in two seasons (spring and summer) by the TERRA satellite’s Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor, were used to compile thematic images, indicating potential contamination of surrounding land. It was intended that a zone of influence could be distinguished for each MRD enabling me to rate the hazard severity. The thematic images I selected included primary minerals (pyrophyllite and chlorite), secondary minerals (copiapite and jarosite), an indicator of uranium-bearing ore (referred to as mincrust) and the normalised difference vegetation index (NDVI). These minerals were chosen as potential indicators of different transport routes of contaminants and I tested their associations with different features and land use. I also tested for seasonal differences in the detection of these minerals, and used NDVI to examine the masking effect of active vegetation. I found GIS to be well suited for combining the various forms of spatial data and providing information about MRDs, aqueous pathways, proximity to vulnerable land uses and impacted areas. However, I found that the potential severity of the hazards posed by each MRD, as indicated by a zone of influence, could not be determined from aerial photographs and ASTER alone. I therefore utilised the findings expressed in the literature survey to assign ratings for the different classes of MRDs. The vulnerability assessment was also supplemented by literature review to rate land uses based on human exposure pathways. I determined that MRDs (including footprints) cover 4.1% of EMM, with slimes dams, totalling 3.5%, occupying the majority of this area. I found that 64% of slimes dams had failed prior to 2003 and I plotted a further 0.6% of EMM covered by visible mine residue spillage. Fifty three percent of MRDs were situated within 100 m of drainage lines or old wetlands, while 52% of these (i.e. 27% of the total) had been constructed in the watercourse. I also found that 15% were constructed on dolomites. Informal settlements were located on or bordering 6% of MRDs, with 41% of MRDs within 1 000 m. Eighty eight percent of MRDs were found within 1 000 m of formal residential areas, 71% within 500 m, and formal settlements were located on or bordering 5% of MRDs. Twenty three percent of MRDs were located within 500 m of agricultural land, while 35% were within 1 000 m; and industrial land use was on 9% of MRDs (footprints), with 40% of MRDs being within 500 m of industrial areas and 61% within 1 000 m I found that chlorite did not provide a ‘signature’ of gold and uranium mine residue, whereas the other four minerals did. I also found that, of the two seasons examined (spring and summer), the best time to take an ASTER image to detect mineral signatures of gold and uranium mine contamination is after a few dry days following the first spring rains. For this reason, I used the ASTER taken in late October (spring) 2003 to examine associations with pathways and land use. I found more pyrophyllite and copiapite on industrial and business land use than background, which I suggest is associated with the settling of windborne dust on large and flat roofs; although, in the case of copiapite this could be related to the oxidation of settled wind blown pyrite material. I found jarosite to be a reliable indicator of mine residue, which, together with mincrust, helped me identify contamination in former agricultural holdings, which are now a township. Although, chemically undefined, mincrust was a useful indicator of contamination, as I found it to be reliably detected on MRDs (including footprints), mine residue spillage, wetlands and other contaminated sites, and absent from known uncontaminated sites. Furthermore, it was not necessarily masked by active vegetation, whereas copiapite, jarosite and pyrophyllite were. Mincrust was also detected on irrigated agricultural land with an odds ratio of between 10 to 36 times greater than for rain-fed. Consequently, the most likely pathway for mincrust is the aqueous. The mincrust signature, together with historical aerial photographs, also assisted me to identify historical mining along Black Reef outcrops, through detection in a wetland upstream of known mining activities. The culmination of my study was a risk class and index for MRDs from which ‘risk maps’ were produced. These maps provide a guide to the level of risk posed by each MRD to the surrounding land use. Of the total 287 MRDs (including footprints) identified in the EMM, 50% were classified lower-risk; 40% medium-risk; 10% higher-risk and 0% as much higher risk. The lower-risk MRDs were predominantly rock dumps, whereas the higher-risk MRDs were slimes dams. The findings from my study will contribute to meaningful recommendations for future land use and enable mining companies, landowners, developers and government to allocate their resources judiciously (i.e. appropriate to the level of risk). The results of this study have been published as: Sutton, M.W., Weiersbye, I.M., Galpin, J.S and Heller, D., 2006. A GIS-based history of gold mine residue deposits and risk assessment of post-mining land uses on the Witwatersrand Basin, South Africa. In: A. B. Fourie and M. Tibbett (eds.), Mine Closure 2006: Proceedings of the 1st International Seminar on Mine Closure, Perth, ISBN: 0-9756756-6-4, pp. 667–678 (Appendix I). Sutton, M.W. and Weiersbye, I.M., 2007. South African legislation pertinent to gold mine closure and residual risk. In: A.B. Fourie, M. Tibbett and J. Wiertz (eds.), Mine Closure 2007: Proceedings of the 2nd International Seminar on Mine Closure, Santiago, ISBN: 978-0-9804185-0-7, pp. 89–102 (Appendix II). Sutton, M.W. and Weiersbye, I.M., 2008. Land use after mine closure – Risk assessment of gold and uranium mine residue deposits on the eastern Witwatersrand, South Africa. In: A.B. Fourie, M. Tibbett, I.M. Weiersbye and P.J. Dye (eds.), Mine Closure 2008: Proceedings of the 3rd International Seminar on Mine Closure, Johannesburg, ISBN: 978-0-9804185-6-9, pp. 363–374 (Appendix III).

Thesis (M. Comm.) -- Central University of Technology, Free State, 2007 / From the Stone Age, each nation or group of people has had a distrust of those different from themselves. This is evidenced in various ways, for example, social welfare given to local residents only, scornful names given to foreigners and other ethnic groups and rituals designed to keep themselves separate from others. These incidents of diversity resulted into an unplanned and emergent set of norms, values and beliefs that exert enormous influence on the way in which an organisation operates, how organisational structure is developed, the integration and adaptation of internal and external relationships, as well as the orientation of the underlying values of the organisation. The main aim of changing culture is to improve organisational performance. To achieve this aim, it requires an understanding of the underlying assumptions and values that determine what is important in an organisation as well as assessment of the impact of culture on operational efficiency. The impact of organisational culture is identified through the negative and positive outcomes of mining activities, and is illustrated by employee satisfaction, job commitment, organisational loyalty, turnover, absenteeism and productivity. The aim of this research study was to identify the characteristics of organisational culture and evaluate the impact of organisational culture on gold mining activities in the Free State. The methodology used in this study comprises of empirical as well as a literature study. Questionnaires and interviews were used to gather information for the empirical study. The empirical study revealed that firstly, organisational culture is created partially by leaders, and that one of the most critical functions of leadership is the creation and the management of culture. Lastly, organisational culture emerges when employees think, believe and act according to the pressures and priorities of their environment. Unfortunately, employees do not set aside their cultural values and lifestyle preferences when they come to work. It is the responsibility of the management to create an environment that is conducive to a healthy working environment. This study established that the necessity to control the workforce productivity need not be accompanied by ruthless or aggressive exploitation of cultural management, but by reliance on employees’ capability to exercise judgement to cope effectively with environmental uncertainty. Rules, norms and strategies developed cannot “fit” every circumstance but encourage conformity rather than creativity, and compliance rather than commitment.

The mining of silver, although not as significant as the mining of gold, has a history of money being made and lost, as well as instances of fraud and theft. In the late 1880s, when silver and lead deposits were discovered 100 km south-east of Pretoria, the Barnato family was quick to invest and float a company to exploit the deposit. To the north of Pretoria, Alois Nellmapius, later famous as the founder of the Hatherly distillery, established a company to mine a silver and copper rich deposit. The Strubens, pioneers of the Witwatersrand gold fields, discovered a silver rich copper deposit on their farm ‘The Willows’ east of Pretoria. The successful silver mining companies listed on the Stock Exchange in Johannesburg soon attracted the attention of the Randlords of Johannesburg and specifically that of H Eckstein & Co. The development of the company’s activities in silver mining in the 1880s and 1890s forms a significant part of this study. The relationship between the mine owners and their managers during the nineteenth century is explored, along with local and international events in politics and economics that had an impact on the mining of silver in South Africa over the period from 1885 to 1999. Silver mining in South Africa has had a ‘rise and fall’ life from the 1880s with three significant periods of investment, mining activity and decline. As with most commodities, prices vary over time. The international metals market has been a dominant factor in the life of the silver mines of greater Pretoria. The relationship between rising and falling international metal prices, and the operating lives of the mines, form a theme throughout this dissertation as it will be shown that the operating periods all coincided with periods of strong metal prices. In the one hundred and fourteen years, coupled with large tonnages of base metals – lead, copper and zinc - the mines produced over ninety-three tons of silver. Over thirty silver mines and ventures were revealed during the research, but discussing all of them in this dissertation was not feasible. It is therefore limited to the history of the seven mines that produced the greatest amounts of silver and other metals such as lead, copper and zinc and how their individual and interrelated histories together form the dominant part of the history of silver mining in the greater Pretoria region. / History / MA (History)

Thesis (MBA)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: Corporate cu~ure is the foundation of businesses today and in every way underties the way business is done. The discovery and subsequent mining of gold during the last century have shaped the gold-mining corporate cu~re; it gave birth to racial segregation and laid the foundation of the system in which the industry finds itse~ today. The purpose of this study is to uncover the deeper patterns of corporate cu~ure that drive visible behaviour and attitudes. Once the root metaphor or main undertying assumptions of the gold-mining corporate cutture have been determined, a process of multilevel, frame-breaking, radical transformation can be initiated. A 'paradigm interplay' approach, which describes cu~re as an explicit variable and an implicit root metaphor, was adopted. Within this frameworK the study aims to explore concepts and meanings of corporate cu~re in a hermeneutic fashion by uncovering the human, expressive, symbolic texture of life in a gold mine. The frameworK provided a way of thinking about organisations, not to present 1001s' or 'methods' for managing or transforming culture, but to think culturally and holistically about the process of transformation. An in-depth investigation into Schein's 'three levels of cu~re' model was necessary in order to derive at the core transformational aspect of the gold-mining corporate culture. An analysis of Schein's model indicated that behavioural characteristics are shaped and determined by undertying values, beliefs and attitudes, which are shared among members of the organisation. If not espoused, these in turn rest upon sets of undertying assumptions that are the innermost core of corporate cu~re. One such a se~ the nature of human relationships, had been identified as the main undertying theme behind the vested interests as well as ingrained paradigms that exist on both sides of a racially divided workforce. The historical background of the industry and cultural perceptions created a shared assumption set that shaped these deep-rooted, embedded mindsets, affecting human relationships significantly. The study made it clear that any transformation attempt could be possible only when one goes deeper than the stated values and norms to understand the undertying assumptions and the true nature of human relationships that drive the visible behaviour and attttudes. The central dimension of this study, the nature of human relationships, referred to the opposing concepts of individualism versus communalism. These opposing paradigms are manifested in the two main management approaches or corporate cultures that exist in South Africa. Many suggested that the acknowledgement and utilisation of the Afrocentric value system, Ubuntu, alongside a Westem individualistic corporate culture are imperative to improve relationships in general and promote humanism. This study proposed that the humane spirit of Ubuntu, a spirit of trus~ caring and respect for human dignity, should be 'married' with the Westem approach to management instead of Ubuntu being adopted as a single framework that may be perceived negatively by the current business community. Thinking culturally', the purpose phrase of this study, succeeded therefore in abandoning the eitheror kind of thinking in favour of a more holistic 'both-and' way of doing. A desired culture of trust, honesty, openness, integrity and non-<liscrimination are sought after - a morally and ethically acceptable corporate culture where empowered employees are inspired rather than driven. Transformation is about the intellectual, social, spiritual and, most important, the emotional resources of the organisation. The 'senses of awareness' that are fundamental to the spirit of Ubuntu, originate from an understanding of our own emotions and secondly the emotions of others. Emotional intelligence is emerging as a major contributor to self-regu lation and is a crucial ingredient of the transformation process of the gold-mining corporate cu~ure . The study recommends the process of transformation can be initiated by creating a focal even~ a moment of concem about the current predicament in which the organisation or, more importa~ the individual finds itse~lhimse~. An act of confrontation may provide a moment of insight that will lead to a reinterpretation of historical and current events. In the process of insight or reflection an increase in seW-knowledge is gained that leads to a new beginning. This study calls for a willingness to change, a motivation to "switch cognitive gears' from an automatic haM of mind to active, conscious reflection of what is right and what is wrong. ~ also calls upon the individual to make the gold mines and South Africa a better place in which to work and live. / AFRIKAANSE OPSOMMING: Die organisasiekultuur van 'n maatskappy is nie alleen die "gom" wat die besigheidsinstelling en sy onderafdelings bind nie, maar in 'n hoe mate ook die onderliggende rede waarom die besigheidsinstelling bestaan. Die punt sal aan die hand van die goudmynbedryf geillustreer word. Die ontdekking en gepaardgaande ekstraksie van goud gedurende die laaste eeu het die organisasiekultuur van die mynwese gevorm. Dit het help beslag gee aan rasse segregasie en het die grondslag gelê vir die sisteem waarin die industrie homself bevind. Die doel van hierdie studie is om die dieper aspekte van organisasiekultuur bloot te Iê - aspekte wat optrede en die sigbare gesindheid aandryf. Die grondliggende paradigma, kern metafore en aannames van die goudmyn industrie sal daarom eers bepaal moet word voordat 'n radikale transformasieproses geinisieer kan word. 'n Benadering van "paradigma wisselwerking" ("tussenspel") is gevolg waarvolgens kultuur beskryf word as 'n eksplisiete verandelike en 'n implisiete kern metafoor. Binne hierdie raamwerk word konsepte en betekenisse van organisasiekultuur binne 'n hermeneutiese metodiek ondersoek. Die doel daarvan is om die menslike, ekspressiewe en simboliese tekstuur van lewenswyse binne die goudmynbedryf te interpreteer. Die raamwerk verskaf 'n denkwyse oor organisasies wat nie daarop gerig is om spesifieke metodes of stappe daar te stel vir die bestuur of transformasie van organisasiekultuur nie. Die doelwit is om kultureel en holisties te dink oor die proses van transformasie. 'n Indiepte ondersoek van Schein se 'drie vlakke' van kultuur was noodsaaklik om die kern transformasie aspek van die Suid Afrikaanse goudmyn kultuur te ontrafel. Daar is bevind dat gedragseienskappe gevorm en bepaal word deur die gesamentlike onderliggende waardes, oortuigings en gesindhede van lede van 'n organisasie. Hierdie eienskappe skakel in by 'n reeks onderliggende aannames wat die binneste kern van organisasiekultuur uitmaak. Die aard van menslike verhoudings, 'n onderliggende aanname, is ge"identifiseer as die hoofonderliggende tema agter die bestaande belange sowel as die ingewortelde paradigmas wat bestaan aan beide kante van die rasverdeelde werksmag. Die historiese agtergrond van die industrie en die kulturele persepsies het 'n gedeelde reeks aannames daargestel wat diep-gewortelde denkpatrone en denkgietsels gevorm het en wat menslike verhoudings aansienlik beinvloed. Die studie maak duidelik dat enige transformasiepoging alleenlik moontliik is indien daar dieper as die bepaalde waardes en norme gedelf word om die onderliggende aannames en denkwyses asook die aard van menslike verhoudings te bepaal wat die sigbare optrede en gesindheid van mense dryf. Die sentraie dimensie van die studie, naamlik die aard van menslike verhoudings, berus op die opponerende konsepte van individualisme en kommunalisme. Hierdie twee konsepte, en die paradigmas wat hulle aandui, word gemanifesteer in die twee hoof bestuursraamwerke van organisasiekultuur wat in Suid Afrika bestaan. Baie navorsers suggereer dat die erkenning en gebruikmaking van die Afrosentriese waardesisteem, Ubuntu, naas 'n westerse individualistiese organisasiekultuur, noodsaaklik is om 'n outentieke humanisme, en verhoudinge in die algemeen te bevorder. Die studie stel voor dat die humane (mens-georianteerde) gees van Ubuntu, 'n gees van vertroue, omgee en respek vir menswaardigheid, saamgesnoer word met die westerse benadering tot bestuur, in plaas daarvan om Ubuntu as 'n enkele raamwerk aan te neern wat dalk negatief waargeneem kan word deur die moderne sakesektor. Die kulturele denkwyse wat gegenereer is in hierdie studie het dus geslaag daarin om die 'of-die-eenof- die-ander' denkwyse te vervang met 'n meer holistiese 'en-en' manier van dink en doen. 'n Kultuur van vertroue, opregtheid, integriteit en geen diskriminasie is noodsaaklik, ofte wel 'n morele en eties aanvaarbare organisasiekultuur waar bemagtigde werkers geinspireer word eerder as gedryf word. Transformasie is gemoeid met die intellektuele, sosiale, spirituele en van groot belang, die emosionele hulpbronne van 'n organisasie. Die aksent op selfbewussyn, wat fundamenteel is vir die gees van Ubuntu, word gegenereer deur 'n verstaan van ons eie emosies, en tweedens die verstaan van die emosies van ander. Emosionele intelligensie het onlangs te voerskyn gekom as 'n belangrike bydraer tot self-regulasie. Dit is 'n beslissende bestanddeel in die transformasieproses van die organisasiekultuur van die goudmynbedryf. Die studie stel voor dat die transformasieproses geinisieer kan word deur 'n spesifieke gebeurtenis wat die fokus word, 'n oomblik van besorgdheid rakende die huidige predikament waarin die industrie of meer belangrik, die individu homself/haarself bevind. Konfrontasie is selfs nodig vir 'n ontwikkeling van 'n oomblik van insig wat aanleiding kan gee tot 'n reinterpretasie van historiese en huidige gebeure. Tydens die proses van insig of nabetragting word 'n toename in selfkennis opgedoen wat lei tot 'n nuwe begin. Die studie vestig die aandag op 'n noodsaaklikheid van 'n verandering van gesindheid en aanvaarding van die eis tot verandering. Dit sluit in 'n verbintenis om kognitiewe 'ratte' te verander vanaf 'n outomatiese sienswyse na 'n aktiewe, bewuste refleksie van wat is reg en wat is verkeerd. Dan kan die goudmyne en Suid Afrika in geheel 'n beter plek gemaak word om in te leef en te werk.

Thesis (MBA)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: DRDGOLD is a mining company forming part of the declining South African gold industry. During the turn of the century, the opportunity to innovate the business model arose. Without proactive intent, DRDGOLD tapped into the opportunity and revised their business model with great success. The success is evident in the improvement of headline earnings from 2002 to 2012. To discuss the changes to the business model, the author conducted a literature review on business models and innovation. From the review, the author selected the Osterwalder Business Model Canvas as the most suitable framework to discuss the changes of the business model. The Osterwalder Business Model includes the business-centric approach and is thus favoured for this discussion. First, the business model was populated with the information to have a comprehensible business model, and secondly, the changes to the business model were identified. The information for the study was sourced from public company documentation, mainly annual reports, secondary sources like Datamonitor, and interviews with four members of the leadership team. The four interviewees were Niel Pretorius, chief executive officer (CEO), Kobus Dissel group financial manager, Charles Symons, chief operating officer (COO), and Craig Barnes, chief financial officer (CFO). The four members had a long-standing relationship with the company and were part of the change process that took place at the company. The period before the study made the business model innovation possible. Firstly, the long mining history around Johannesburg produced the mine dumps that formed the core resource of the operations. Secondly, the craze to buy anything that looks like gold during the end of the 1990s introduced DRDGOLD to the surface retreatment operations with the purchase of Crown. The environment of the operations started to change, not only the operating environment, but also the other stakeholders. The importance of the community grew, the dividend yield to the shareholder increased in importance, the engagement with the regulators changed to a proactive engagement, and the environment was managed for a long-term perspective. The risks and returns for DRDGOLD started to misalign. The risk of pursuing the underground operations further increased considerably and unintentionally drove the costs up. Within the context of South Africa, the returns of underground operations started to erode as unscheduled stoppages increased. These stoppages were caused by events outside the control of the company, for example power failures, seismic activities and labour unrest. DRDGOLD repositioned itself as a factory that has a high throughput in material on a 24/7-operation rooster. The yields are significantly lower than the underground operations, but the risk of the new setup is also reduced greatly. Seismic activity does not impact the operations anymore. The production time of the operations has increased with less unscheduled stoppages. DRDGOLD changed to have itself valued on the discounted cash flow (DCF) method. The company’s share price is now valued on the DCF method based on the operational revenues. This is contrary to the gold mining industry valuation of South African mines. These mines are mainly valued on the reserves statement multiplied by the commodity price. The share price of DRDGOLD is heavily leveraged on the spot price of gold and the exchange rate of the South African Rand (ZAR) to the United States Dollar (US$). Any movement in these two indicators will have a significant impact on the share price.

Thesis (MBA)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The mining bubble is over, and mining companies in South Africa are under pressure to remain viable concerns. This forces companies to cut their cost through organisational restructuring, closing down of mines and cost-saving technologies. All of these result in job losses in the mining sector. However, the companies do have a social responsibility to help uplift and create jobs in the mining areas and labour-sending regions. The study reviews examples of corporate-social-development projects of mines that relate to agriculture. Furthermore, the study looks at projects stemming from the government’s desire for land reform and rural social-economic upliftment of previously disadvantaged communities. In this context contract farming is an ideal way to tackle comprehensively the re-employment challenges. Against that background, which combines literature review and brief summaries of case studies, the dissertation reviews contract farming as an approach towards agricultural development and job creation. The lessons from the socio-economic development projects, rural-reforms and contract-farming projects are used as inputs to evolve a framework for the local approach to contract farming, related to mining areas. This includes considerations of implementation challenges likely to be experienced.

D.Litt. et Phil. (History) / Please refer to full text to view abstract

Thesis (Ph.D.)--University of the Witwatersrand, Faculty of Engineering, 1988. / 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: <y vel excavations because typical hanging- and foot-walls are subjected to compressive horizontal strain and thus stress, the numerical models identified alternative locations o f Ix 'sile stress and also mechanisms which could induce secondary tensile stresses, A failure criterion has therefore been identified as the most likely cause of large scale fracturing while shear fracturing may only occur in the absence of such tensile stresses .and only as a consequence of failure localisation in damaged rock rather than fracture propagation (in solid rock). Geological discontinuities can easily induce tensile stresses vVher mobilised and may even replace the mining induced fractures by offering a more efficient meat s for energy release. The latter possibility is a true three dimensional issue which has not be en addressed any further in this study, but may be very relevant to jointed rock. Although dynamic failure has not directly been addressed, one of the micliamsms lor brittle, and thus stress relieving, failure under compressive strass conditi ons has been investigated in detail, namely shear fracturing. Shear fractures are effect vely the only discontinuities which allow for stress relief under such conditi ons', in the ibaence of preexisting, geological discontinuities, and are therefore quite rele vant to dynamic rock failure, such as rock bursts, in deep level mining conditions. Potential mechanisms for shear fracture formation and the numerical simulation of these features have been investigated and this may especially assist further research into rock bursts.

A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Science in Mining Engineering. February, 2016 / Mineral 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.

A research report submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in partial fulfillment of the requirements for the degree of Master of Science in Environmental Science / Pollution originating from mine tailings is currently one of the environmental problems South Africa has to deal with. Because of the large number of tailings impoundments and their changing status, authorities are battling to keep their records and controls up to date. This project is aimed at investigating the use of remote sensing as a way of conducting surveys of mine tailings efficiently, regularly and at a low cost. Mine tailings impoundments of the Witwatersrand in Gauteng provide an ideal study area because of the large number of tailings dams of different sizes and conditions and the availability of satellite images and aerial photographs covering the area. Tailings impoundments conditions are analysed through satellite images, airborne multi-spectral data and aerial photographs captured during the Safari 2000 dry season campaign. Remote sensing interpretation of colour composites of multi-spectral bands, Principal Components and supervised and unsupervised classifications are the methods of analysis used. The overall goal of the project has been achieved through the production of a comprehensive database of tailings impoundments and their rehabilitation status, in an accessible format, containing identity, coordinates, area, rehabilitation status and owner of each tailings impoundment, map them and end up with a comprehensive database of tailings impoundment on the Witwatersrand. / AC2017