3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item The geological setting of uranium mineralisation in the Rössing Area, Namibia(2015) Gray, Timothy M.The geology of the Rössing uranium mine area has been mapped and described through compilation and interpretation of all available data, underpinned by field traversing and sampling. The understanding of the stratigraphic and structural setting of granite-hosted uranium mineralisation in the wider Rössing area has in particular been refined. HyMap hyperspectral imagery significantly contributed to resolving the mapped geology in detail. Descriptions of the stratigraphic sequence have been compiled and augmented particularly within the upper parts of the Damaran stratigraphy. A three member diamictite-iron formation stratigraphy is constrained within the Chuos Formation whilst eight members are identified through the Arandis to Karibib Formation sequence. The detailed resolution of the stratigraphy has also resolved many aspects of the structural geology in the area. Pre-D3 extension is expressed as a sheared basement-cover interface, major boudinage of stratigraphic units, and exploitation of such dilational zones by early alaskite intrusions. Within the F2-F4 fold phases identified across the area, major dome and basin and hook geometries result from F2-F3 fold interference. D3 to D4 deformation was progressive where the latter consisted of the development of early, minor north-northeast trending folds and left lateral faulting. Map relationships suggest this was followed by the formation of north-northeast oriented transtensional shear zones highly oblique to pre-D4 litho-structural orientations and into which uranium-bearing granitic melts were focused. Alaskite generation is attributed to migmatisation and partial melting of potassic meta-psammites during lower granulite facies metamorphism. The sequence of alaskite intrusions is correlated with the scheme applied to the nearby Goanikontes uranium deposit with varying confidence. At Rössing SJ the intrusion of voluminous uranium-bearing alaskite melt material was especially facilitated by superimposition of a north-northeast trending shear zone upon both a major F2-F3 fold interference structure and a pre-existing D4 fault zone. Uraniferous alaskites at the SH and SK ore bodies intrude peripheral F3 fold structures superimposed on the F2 folds. In the Z20-Z19-Z17 to Rössing South Zone 1 area, mineralised alaskites occur within the Rössing, Arandis and Karibib Formations, where doming of the Rössing South anticline is also demonstrated to be due to F2-F3 fold interference.Item SA's trade policy: the impact of China's economic slowdown on South Africa's mineral commodity trade(2018) Mathebula, PeacefulThe economic relations between China and South Africa have been largely based on the mineral resources of South Africa. Hence, China’s rapid economic growth of recent had positive disruptive impacts on South Africa’s economy. Conversely, the recent slowdown of China’s economic growth has had negative effects on South Africa. By assessing the value of mineral product exports from South Africa to China from 2001 till recent, this research project provides an outline showing that the decline in China’s economic growth has not been advantageous to South Africa’s economic economy. It seems that as China and South Africa’s comprehensive strategic partnership strengthens, South Africa will continue to be affected by the changes in commodity prices associated with China’s economic growth. This also includes changes in mineral input growth. Based on the findings of the spillover effects of this decline in SA’s mineral export value to China, this research project aims to encourage the policy-makers of South Africa to see the need for their current policies to be re-assessed. This re-assessment is for determining whether their policies are capable of enabling their economies to handle the disruptive changes that can occur in their trade relations with a giant economy like China. The result should be restructuring their policies so they would have buffers for changes in global mineral prices and demand, as well as make them better prepared to enter beneficial engagements with China, when its economy grows stronger againItem An assessment of the long-term commodity price assumptions on the Mineral Reserve estimates of South African gold and platinum mining companies from 200 to 2016(2018) Maseko, VulaniIn the 19th and 20th centuries mining underwent an evolution from the exploitation of small mining properties by individual claim holders to consolidation and the formation of multinational mining companies. With the rise of multinational mining companies came the advent of international finance in the mining industry. As companies developed and operated larger mining projects across several geographies, their capital requirements increased. As the number of investors in mining projects increased, through the raising of finance on international capital markets, so did the importance of mineral asset reporting. While governments and other organisations reported on the mineral inventories of countries, international mining companies had to report on only the economic portions of their mineral assets. The early days of international mineral asset reporting resulted in several reporting scandals where investors were misled by unscrupulous companies and individuals who reported false mineral deposit quantities and qualities in an attempt to manipulate investor sentiment for personal profit. As a result of these reporting scandals, the international mineral reporting codes were developed to increase the quality and transparency of mineral asset reporting and to protect investors. In the case of South Africa, the South African Code for the Reporting of Exploration Results, Mineral Resources and Mineral Reserves (SAMREC) Code, was first published in March 2000 and adopted by the Johannesburg Stock Exchange (JSE) later that year. The SAMREC Code, like the other international mineral reporting codes, aimed to ensure quality and transparent mineral asset reporting. Mineral Resources and Mineral Reserves are collectively a backbone asset for any company in the minerals industry This research study assessed the reporting of Mineral Reserves in South Africa in the period from the introduction of the SAMREC Code, in 2000, to 2016, with specific focus on reporting by South Africa’s gold and platinum mining companies. Mineral Reserve reporting was identified as a key focus, as Mineral Reserves are the economically mineable portions of Mineral Resources, and therefore give a better indication of the prospects of mining companies in the short to medium term. The literature review conducted as a part of this research study indicated that long-term commodity prices are the most important modifying factors used in Mineral Reserve estimation, hence there was a specific focus on the long-term commodity prices used in the Mineral Reserve estimates of South Africa’s gold and platinum mining companies. However, the relationships between the Mineral Reserve estimates and the other modifying factors were also assessed. The research demonstrated a general improvement in the quality of Mineral Reserve reporting by South Africa’s gold and platinum mining companies since the introduction of the SAMREC Code in 2000. However, the quality of Mineral Reserve reporting by the platinum mining companies was found be considerably less detailed to that of the gold mining companies. The long-term gold prices of the gold mining companies were found to be relatively conservative, often falling below prevailing spot prices, while the long-term prices of the platinum mining companies were often found to be more optimistic, with long-term platinum group metals (PGM) prices that were generally above prevailing spot prices. This research study also assessed the relationship between the Mineral Reserve estimates of South African gold and platinum mining companies and their reported modifying factors, with a specific focus on long-term commodity prices. The coefficient of determination (R2) was used to assess the relationship between Mineral Reserve estimates and their associated modifying factors. The statistical analysis conducted demonstrated that the Mineral Reserves of South African gold and platinum mining companies between 2000 and 2016 were often most sensitive to changes in long-term commodity prices, relative to the other modifying factors. The long-term commodity price assumptions of mining companies affect the value at which assets are recognised on their balance sheets. Sustained and fundamental differences between the long-term commodity price assumptions of mining companies and prevailing spot commodity prices may result in mining companies having to record impairments against their assets. In the period between 2000 and 2016, South African gold mining companies recognised a total of ZAR46bn (in nominal terms) in non-financial asset impairments, while platinum mining companies impaired their non-financial assets by a total of ZAR54bn. An assessment of the non-financial asset impairments of South Africa’s platinum and gold mining companies revealed that the least number of impairments were recorded when long-term commodity prices were within 5% of spot prices, suggesting that this should be the range within which long-term prices should be determined to limit future impairments.Item Inclusive wealth as a metric of sustainable mining: a case study in the platinum sector(2017) Pabwe, Irene V.Challenges in the mining and extractive sector include their ability to show that they contribute towards the welfare and well-being of the present generation without compromising the potential benefits of the future generation to enjoy a better quality and standard of living from their environment. This research aims at establishing whether Inclusive Wealth, an approach to assessing of sustainable development originally for use at the national scale, is applicable and useful when applied at the scale of an individual mine, i.e. locally. A case study of Mogalakwena platinum mine is carried out. The concept of Inclusive Wealth allows that sustainability objectives can be achieved in an extractive industry provided that natural capital (in the form of mineral resources, in this case) is converted into other forms of capital, such as social and manufactured capital, efficiently and thus does not result in a net loss of total (‘inclusive’) wealth, where wealth is consistently defined as the potential to deliver future benefits. The Inclusive Wealth framework has been criticised for its theoretical assumptions and gaps in data availability. This research project shows that Inclusive Wealth has the capacity to act as satisfactory sustainability indicator at a local level, despite being better explored and thus more comprehensive at a national level. The objective of the research was to calculate inclusive wealth impacts of Mogalakwena Platinum mine in order understand the balance between social, environmental and financial objectives. It also looked at the changes in Natural Capital over time, throughout the life cycle of the mine, through quantifying the time course of flows of key ecosystem services. The research also looks at the background of sustainable development, debates around sustainability and ecosystem services and their valuation. Desktop research was conducted with use of company reports, Environmental Management Programme Reports, Sustainability Reports, financial or stock market reports. These indicators derived from these sources were projected for the lifetime of the mine.Item A framework to harmonise mineral asset valuation methodologies with existing and emerging financial reporting requirements(2017) Njowa, GodknowsOne of the consequences of globalisation in the extractive industries is the necessity to apply uniform accounting and valuation standards that are clearly understood and consistently applied by the global stakeholder community. At the beginning of the 20th century it was realised, mainly by the major mining countries that the extractive industries is one of the biggest sectors globally. In the extractive industries the single most important asset is the Mineral Resources and Mineral Reserves, yet this is not reflected anywhere in the financial statements. The major mining countries, through their mining institutes, realised that there was a need to develop standards and guidelines to align and standardise the definitions of Exploration Results, Mineral Resources and Mineral Reserves, which was achieved through the CRIRSCO template. From the accounting fraternity, several organisations also realised the need for an accounting standard specific to the extractive industries, specifically for financial reporting. Attempts by the IVSC and IASB to develop a global accounting standard for the extractive industry attests to the global requirement to develop internationally recognised valuation guidelines or a global framework for the valuation of mineral assets. Both the mining institutions and accounting standards setting boards have been working in isolation to develop a globally acceptable standard or guideline for the extractive industries, and neither has been successful due to the inherent complexities. The harmonisation of the national codes for reporting of Mineral Resources and Mineral Reserves through the CRIRSCO template, provides global common understanding. However, the national mineral asset valuation (MAV) codes, are needed to develop a similar international template. The CRIRSCO template provided a strong foundation on which the IMVAL template was developed. As part of this research a framework was developed to harmonise the national MAV Codes. Various authors have argued that there is no globally accepted standard or guideline for the valuation of extractive industries assets, nor is there a specific accounting standard for extractive industries. MAV is still an emerging discipline, coupled with the fact that financial reporting in the mineral industry is not yet fully developed, as IFRS 6 appears to be the only mineral specific financial reporting standard. This is supported by the fact that currently there is a lack of a comprehensive accounting standard for the extractive industries to guide the accounting, recognising and presenting these assets in the primary financial statements. This thesis argues that there is a gap between reflecting and accounting for Mineral Resources and Mineral Reserves in the financial reporting systems, and how these mineral assets are valued and reported. These identified gaps between MAV methodologies and financial reporting requirements formed the basis of this work. Hence this thesis develops a framework to harmonise the existing and emerging financial reporting requirements and MAV methodologies. This framework is applicable to developmental projects and operating mines, and was validated by applying the framework to a real life case study. Turquoise Hill Resources (Turquoise), which owns Oyu Tolgoi copper-gold mine in Mongolia, was selected as a good case study, due to the fact that Turquoise owns and operates this single multicommodity mineral asset, with information available in the public domain. Hence the value of Turquoise on the stock exchange is driven by the fundamental value of the mineral asset only. The results of the proposed framework showed the highest correlation coefficient of 0.77, meaning that there is a strong correlation between proposed framework and the proxy company value selected. It is concluded that the proposed framework to harmonise MAV methodologies and the emerging financial reporting requirements can be applied to estimate values for companies in the mineral industries.Item Modelling of sorption of trace elements in an agricultural soil impacted by mining activities(2017) Mosai, Alseno KagisoThe development of the economy of South Africa and many other countries has been highly dependent on mining industries. Minerals such as gold, platinum, diamond and many others have been mined and continue to be mined. Despite the importance of these minerals, their processing comes with social and environmental problems. During the processing of these minerals, trace elements such as copper, chromium, nickel, mercury, uranium, molybdenum and many others are released as wastes into the environment either, directly or indirectly. The release of the elements into the soil is of concern due to the possibility of groundwater system contamination. The presence of these elements in the groundwater system poses serious challenges to the wellbeing of life forms, due to their toxicity, when they exceed threshold limits. From the processing plants, these elements could be released onto the soil, and mobilise to groundwater, increasing the already existing environmental crisis due to water pollution. Once these elements are in the water, access to living organisms becomes easier through the food chain. Some of these elements are not biodegradable and thus persist in the environment as well as in the bodies of living organisms. They can cause serious health problems because of their toxicity effect. In humans, these elements can be carcinogenic, and also cause chronic disorders, kidney failures, defects in infants, bone and vascular diseases which could also be lethal. It is therefore of importance that these elements are neither bioavailable nor bioaccessible to living organisms. When these elements are mobile in the soil, the probability of reaching groundwater increases. Water, an important natural resource should always be protected from such pollutants. The demand for unpolluted water has been rising every year in the world due to increasing population, extended droughts and improper disposal. This research was dedicated to determining the behaviour of elements in an agricultural soil impacted by mining activities. Agricultural soils are sometimes exposed to pollutants that could originate from dust fallout or precipitation; fertilisers and manure; pesticides; and water used for irrigation. Understanding the iv processes that control the distribution of these pollutants in agricultural soils is an important risk assessment measure, considering that such pollutants have the potential of being taken up by crops and vegetables or transported to groundwater. In this study, a soil on a farm that grows vegetables for commercial purpose. Cabbage, spinach, carrots and potatoes are some of the vegetables grown on the plot and sold to markets in Pretoria and Johannesburg. The plot is in the vicinity of smelting operations in the North West Province. The mobility of trace elements in the soil can be controlled, depending on the type and properties of soil. Hence in this research, the ability of the soil to adsorb elements entering the soil is studied. The batch experimental work was performed to determine the effect of pH, initial concentration (5 - 100 mg/L), competing ions (Fe3+, Ca2+, Co2+, Mg2+, K+, Ni2+ and Zn2+), fertilisers (ammonium nitrate, ammonium phosphate and calcium chloride) and plant exudates (acetic acid, citric acid and oxalic acid as well as ethylenediaminetetraacetic acid (EDTA) which is often used as proxy organic ligand (found in manure)) on the adsorption of cadmium (Cd), copper (Cu) and chromium (Cr) onto an agricultural soil. The PHREEQC geochemical modelling code was used to complement experimental methods in predicting processes and to further assess the leaching behaviour of the elements. Powder X-ray diffraction (PXRD) and X-ray fluorescence (XRF) were used to determine the mineralization of the soil. The structural features of the soil were determined using Fourier Transform Infrared spectroscopy (FTIR) and the element content was determined using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). The point of zero charge (PZC) of the soil was found to be 8.3 and the cation exchange capacity (CEC) of 51.6 meq/ 100g. In the absence of fertilisers and plant exudates, the soil exhibited a similar high adsorption for elements at all initial concentrations by all the elements. Most (> 90%) of the elements were adsorbed within the first 3 minutes of contact with the soil. Langmuir, Freundlich and Dubinin-Radushkevich adsorption isotherms were used to describe the experimental data for the elements. Kinetic rates were modelled using pseudo first-order and pseudo second-order equations. Pseudo v second-order gave the best fit for all the elements (R2 >0.999) indicating chemisorption. The effect of pH on Cd and Cu was insignificant however, the adsorption of Cr decreased with pH. The presence of competing ions decreased the adsorption of cadmium more than that of the other analyte elements. The soil was generally effective in adsorbing and retaining the elements. However, the retention was highly dependent on elemental speciation and prevailing conditions e.g. pH (as in the case of Cu and Cr). Such changes in conditions would have implications for groundwater quality. The effect of plant exudates and EDTA was studied and the results showed that low molecular weight organic acids (LMWOAs) viz acetic acid (AA), citric acid (CA) and oxalic acid (OA) and EDTA significantly (p < 0.05) decreased the adsorption capacity of the elements onto the agricultural soil. AA had the least effect on the adsorption capacity of the elements whereas OA and EDTA strongly prevented the adsorption of the elements. Moreover, some of the elements which were already in the soil including those which were not under study such as Ca and Mg were desorbed from the soil by OA and EDTA. Thus, the mobility of the elements was increased by the presence of plant exudates, increasing groundwater contamination and consequently threatening the health of living organisms. Agrochemicals such as fertilisers, stabilizers and pesticides are constantly applied to agricultural soils to improve the fertility of the soil for better crop production however; their presence may affect the mobility and bioavailability of elements in the soil. The effect of ammonium nitrate and ammonium phosphate as well as calcium chloride on the adsorption of Cd, Cu and Cr onto an agricultural soil was studied. The effects of initial concentrations of the elements (5 – 50 mg/L), concentrations of fertilisers (0.01 – 0.1 mol/L) and pH (3 - 8) on the adsorption of Cd, Cu and Cr were studied. The initial concentration of the elements and the concentration of fertilisers had no significant effect (p > 0.05) on the adsorption capacities of Cu and Cr at pH 5. But, ammonium nitrate and calcium chloride decreased the adsorption capacity of Cd. The adsorption of Cd onto the soil was reduced as the concentration of fertilisers increased. The adsorption of Cd was lower than that of Cu and Cr at all pH values. The agricultural soil was found to vi be an effective adsorbent in preventing the mobility of Cu and Cr in the presence of fertilisers but not for Cd whose adsorption was significantly affected by the presence of ammonium nitrate and calcium chloride. A continuous flow fixed-bed column script with specified conditions simulating the natural environment was utilised in PHREEQC for column studies. The geochemical computer model PHREEQC can simulate solute transport in soil surfaces. The effect of initial concentration (100 and 300 mg/L) of the elements, column bed depth (5 and 10 cm) and pH (3, 5, 7 and 10) were considered in this study. The adsorption capacity was affected by initial concentration of the elements since the breakthrough curves at higher analyte concentrations were reached at lower pore volumes than at low concentrations. This can be attributed to the fast occupation of active sites of the soil at higher concentrations. The results from PHREEQC indicated that the conditions used would lead to the oxidation of Cr3+ to Cr6+ leading to the formation of HCrO4- and Cr2O72- which were not favoured for adsorption by soil surfaces due to high solubility. This could have potential implications on the quality of groundwater in regions with similar conditions. Thus, the leaching of Cr6+ onto the agricultural soil will be high in areas where remediation techniques are not applied. The changing of bed depth from 5 to 10 cm did not have an effect on the adsorption of the elements. The ability of the soil surfaces to adsorb Cd and Cu even at lower bed depth implies that the soil will be effective in preventing the leaching of the elements to groundwater due to strong surface interactions of the elements with the soil. The results from PHREEQC showed that the adsorption of Cd and Cr onto the soil surface was not affected by pH. The results for Cr were contradicting with those obtained from laboratory experiments which could be due to the conditions used in PHREEQC. The change in the speciation of Cu at basic conditions decreased the ability of Cu adsorption onto the soil surfaces. The Cu2+ was converted to Cu(OH)2 which were large in size and thus only a small amount could be adsorbed since the other adsorption sites were covered by the large species. This research had notable outputs in the form of publications which will form an important repository of information.Item Micro analytical observation of elemental distribution in arbuscular mycorrhizal (AM) roots from mining sites in South Africa and identification of their AM fungi(2016) Zamxaka, MtutuzeliSouth Africa, as one of the leaders in mining industry, due to the variety and quantity of minerals produced, has been and is still producing a number of mine tailings which are contaminated by heavy metals. Heavy metals are very harmful to plants and especially to human beings and animals due to their non-biodegradable nature. The problem of environmental metal pollution could be combated by the establishment of Arbuscular Mycorrhiza (AM) vegetation on the surface of mine tailings. Besides the toxicity of the substrate, such areas usually lack essential nutrients (mainly N, P, and K) and organic matter. AM fungi contribute to soil structure by forming micro- and macro- soil aggregates within the net of external hyphae. Their presence may reduce stress caused by lack of nutrients or organic matter and increase plant resistance to pathogens, drought and heavy metals. Therefore, mycorrhizal fungi may become the key factor in successful plant revegetation of heavy-metal-polluted areas by promoting the success of plant establishment and increasing soil fertility and quality. The aim of this project was to identify AM fungi from a number of heavy metal sites in South Africa using both morphological and molecular techniques, followed by the evaluation of heavy metal distribution and localisation in mycorrhizal roots. Soil samples were collected from three different provinces, namely: Gauteng, Mpumalanga and North West provinces. The sites were selected based on their historical and current heavy metal contamination. Indigenous AM fungal isolates (which are adapted to local soil conditions) can stimulate plant growth better than non-indigenous isolates. AM fungal spores were isolated from 100g of representative soil sample by the wet sieving and decanting method, followed by assessment of spore numbers and infective propagules. The spores of a subset of the pot samples were mounted on microscope slides in polyvinyl lactic acid glycerol and identified by morphological characteristics to the level of genus or species. Most of the spores counted were observed in a 45 μm sieve. These spores were tiny and had different sizes, colours and shapes. The majority of the observed spores were small, brown and oval in shape. For morphological identification, plant roots were stained and hyphae were found to be the most abundant in roots. For molecular identification, two sets of nested PCR primers, namely NS1 & NS4 coupled with AML1 & AML2, were employed in this study due to their ability to amplify all subgroups of arbuscular mycorrhizal fungi (AM fungal, Glomeromycota), while excluding sequences from other organisms. Through both morphological characteristics and molecular identification, the following fungal genera were identified for the first time in the studied sites in South Africa. The study identified a total of 14 AM fungal genera and 55 AM fungal species, which are: Glomus (15), Acaulospora (11), Scutellospora (6), Gigaspora (6), Rhizophagus (3), Funneliformis (3), Archaeospora (2), Claroideoglomus (2), Ambispora (2), Sclerocystis (1), Fuscutata (1), Entrophospora (1), Diversispora (1), Paraglomus (1). Both Glomus and Acualospora have been observed to be the highest occurring genera in the analysed soil samples, followed by Scutellospora and Gigaspora and others mentioned. PIXE technique was successful in localising elemental concentration in both plant roots and AM fungal structures, as well as in indicating the large vesicles in root tissue. AM fungal structures in the outer cortex or outer epidermal layer of the root cross-sections were observable, as shown by the more significantly enriched Si in the vesicles and arbuscules. Distinctive elemental maps can be used to localise sites of colonisation and verification of the symbiotic nature of the tissue. This indicates that a range of metals can be sequestered in AM fungal structures above levels in surrounding host root tissue, and demonstrates the potential of Micro-PIXE to determine metal accumulation and elemental distribution in mycorrhizal plant roots and inter-and intracellular AM fungal structures. This research highlights the potential of AM fungi for inoculation of plants as a prerequisite for successful restoration of heavy metal contaminated soils. It also illustrates the importance of AM fungal diversity in selected high heavy metal (HM) sites in RSA, particularly in the North West and the Gauteng gold mining slime dams. Therefore, phytoremediation of mine tailings by mycorrhizal plants seems to be one of the most promising lines of research on mine tailings contamination by heavy metals. The strategies which evolved during this project have great potential for phytoremediation of toxic mining sites, and thus can help mitigate the environmental problems, especially in the mining waste sites.