This dissertation presents the findings of a project where, following investigation and assessment, a million tonnes of sand and gravel at a contaminated former US Air Force Base was excavated for use as aggregate. The process required on-site screening for petroleum hydrocarbons of over 7,000 soil samples and provided an opportunity to assess the efficiency of the investigation, assess the application of geophysics of hydrocarbon contaminated sites, and look at the role of aggregate extraction in the contaminated land industry.

This thesis presents research into the binding, extraction and transport of the hexachloroplatinate anion, [PtCl6]2-, by organic receptors in a solvent extraction process. The target anion is produced during the processing of platinum-containing ores and the aim was to develop reagents that can selectively extract [PtCl6]2- to optimise the recovery of platinum. Chapter One outlines reasons for the interest in [PtCI6]2-and provides an overview of the processes and techniques used to refine precious metals. An introduction to anion coordination chemistry relevant to the research project is also presented. Chapter Two discusses the design features incorporated into organic receptors to enable strong and selective binding of [PtCl6]2-. These features include a tertiary amine protonation site, hydrogen-bond donor groups and organic solubilising moieties. The synthesis of a series of functionalised tripodal tris(2-aminoethyl)amine based receptors with sulfonamide, amide, urea, thiourea or pyrrole NH hydrogenbond donor groups are reported. Complexation reactions between the receptors and H2PtCl6 to form [(LH)2PtCl6] ion pairs are discussed. Crystallographic analysis of the [(LH)2PtCl6]complexes with TREN-based sulfonamide, urea and amide receptors confirms the presence of hydrogen-bonds between the NH donor groups and the outer-sphere of [PtCl6]2-. The low organic solubility of the complexes prevented the study of these systems in solvent extractions. Chapter Three describes the variation of terminal substituents of the tripodal receptors with the aim of improving the organic solubility of the extractants and their [PtCl6]2-complexes. In these "second generation" receptors the terminal substituents assessed include 3, 5-dimethylphenyl, 4-iso-propylphenyl, 4-tert-butylphenyl, 3, 5- dimethoxyphenyl, 3, 4 dimethoxypheynl and 3, 4, 5-trimethoxyphenyl. Through reaction of the receptors with H2PtCl6 the solubility of the resultant complexes are assessed. Chapter Four describes the development of an optimised solvent extraction method to study the extractive behaviour receptors. A pH swing mechanism is utilised to control the uptake and release of [PtCl6]2-. The extraction results for trioctylamine and the soluble tripodal urea and amide receptors are compared. Attempts are also made to confirm the stoichiometry of the complex in solution. Chapter Five describes the synthesis of tris(2-aminoethyl)amine based receptors with hydrogen- and halogen-bond donor groups with the aim of increasing the strength of the interaction between a receptor and [PtCI6]2-. Receptors with an extended tripodal scaffold based on a tris(3-aminopropyl)amine with urea and amide moieties are also presented. The results of the complexation reactions and solvent extraction studies with these modified extractants are presented. Chapter Six presents the design and synthesis of bipodal and monopodal receptors in order to assess the role of the number of hydrogen-bond donor functionalised arms. The results of the solvent extraction studies with these receptors are discussed and comparisons made between tripodal, bipodal and monopodal extractants. The crystallographic analysis of the [(LH)2PtCl6] complexes formed between the bipodal urea and amide receptors is described. Chapter Seven highlights the important findings from this work. Conclusions are drawn as to the optimum receptor system developed and this is compared to the extractant system thought to be in current use for the extraction and transport of [PtCl6]2-.

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A Dissertation submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the Degree of the Master of Science / Drilled specimens from four types of rocks, namely Quartzite, Norite, Sandstone and Coal encountered in the South African mining environment were tested to determine their fracture toughness coefficients, using International Society for Rock Mechanics (I...) standards. The tests were conducted using a MTS servo-controlled testing machine in displacement control mode. (Abbreviation abstract) / Andrew Chakane 2018

A research report submitted to the Faculty of Engineering and the Build Environment, University of the Witwatersrand, in partial fulfillment of the requirements for the degree of Master of Science in Engineering Johannesburg, 2014 / The South African power crisis and corresponding rising costs experienced since 2008, created a paradigm shift in terms of electricity use. The mining sector is the second highest consumer of electricity with metalliferous mines being accountable for 80% of the total power. Recent studies revealed that underground ventilation and cooling accounts for 30% to 40% of total electricity costs in an underground metalliferous mine. Hence the need to look at ways to reduce electricity consumption in ventilation and cooling. Work has been done on optimising efficiencies of ventilation and refrigeration systems of underground mines. Currently, the high energy consumption is driven by efforts to achieve a thermally acceptable environment for workers (manned) in deep metalliferous mines which is currently between 27ºC (wb) and 29ºC (wb). However, no detailed study has been done looking at increasing thermally acceptable environments for deep level metalliferous mine. In this study the impact of increasing rejection temperature to 40ºC (db) was assessed in the automated (unmanned) scenario at a maximum depth of 2811 metres. Then the power demand was compared with the manned scenario. The results proved that automation in an underground mine has the potential of reducing electricity cost of ventilation and cooling by more than 50%. For example, the production rate of about 200 kilo-tons per month yield an annual cost saving of R71 million on electricity. These cost savings can be used to justify automation systems. Automation removes workers from the hazardous environment and replaces them with equipment which can withstand harsher conditions. The introduction of an automation system in underground mines would not come risk-free. Currently, automation systems have not yet reached a level of removing workers completely from underground.There are instances that would require workers to enter production zones. A Bow-Tie risk analysis was used to show the hazards that workers would be exposed to and prevention controls and responses to mitigate the impact the risks. / MT2017

The participation of indigenous communities and use of indigenous knowledge systems (IKS) in environmental governance is provided for in several international and national environmental legislation and policies. In South Africa, the National Environmental Management Act 107 of 1998 (NEMA) in Chapter 1, Principle 4g requires that decisions must take into account the interests, needs and values of all interested and affected parties, and this includes recognising all forms of knowledge, including traditional and ordinary knowledge. This study investigated the Environmental Impact Assessment process (EIA) in mining developments in three rural communities in Limpopo Province, South Africa with regards to the effectiveness of public participation in fostering the incorporation of IKS. The qualitative research design used in this study employed several research methods through the utilisation of 3 villages as a case study. Semi-structured interviews, a focus group discussion and document analysis were used to collect information regarding the public participation process and the integration of IKS into EIAs. This report illustrates that IKS exists in rural communities and some of it is relevant to be incorporated in EIAs. This research study has shown that while expert knowledge dominates the EIA process, there is no indication that this is done deliberately to exclude IKS. This study has also revealed that the public participation process has a number of weaknesses such as in the selection and composition of community stakeholders and communication procedures. Suspicions also developed amongst the villagers of community representatives being bribed by the mine, and infighting started within community committees resulting in some community members losing trust in the committees. The disagreements with regards to the integrity of community committees created divisions and this negatively impacted on the public participation process. However, despite these weaknesses, if capacity building for both EIA experts and rural communities is done, the public participation process has potential as a tool to aid the integration of IKS into EIAs.

Low temperature plasma surface alloying with nitrogen (nitriding), carbon (carburising) and both (carbonitriding) has been successfully employed in hardening medical grade ASTM F138, ASTM F1586 and ASTM F2581 as well as engineering grade AISI 316 by the formation of a modified layer better known as S-phase or expanded austenite. In this study, systematic plasma treatments and characterisation were performed on medical grade stainless steel in order to establish the optimised treatment conditions, especially temperature, which can maximise the hardened case depth without any detriment in corrosion resistance. The surface of a biomaterial must not adversely affect its biological environment and return the material surface must not be adversely affected by the surrounding host tissue and fluids. Experimental results have shown that this duality of concern can be addressed by creating S-phase. It has been shown that low-temperature nitriding (430°C), carburising (500°C) and carbonitriding (430°C) improved the localised corrosion, corrosion-wear and fretting-wear resistance of these medical grade stainless. Also biocompatibility studies have proved that these hardened surfaces were biocompatible under the realms of the tests conducted in this study therefore the use of hardened medical grade austenitic stainless steel might be suitable in implant applications.

This thesis reports on an environmentally-friendly pultrusion technique for the production of fibre-reinforced composites, termed as “clean pultrusion”. In this new manufacturing technique, the resin bath used in the conventional pultrusion was replaced with a custom-built resin impregnator. The resin impregnator was designed and built to impregnate the rovings using a combination of pin, injection and capillary-based impregnation. An integral aspect of the clean pultrusion process was spreading of the filaments in the rovings, via mechanical means, prior to impregnation. An automated fibre spreading rig was designed and built based on “tension-release” process. The rig-design was optimised using Taguchi method. The physical, mechanical and thermo-mechanical properties of the composites pultruded using the clean and conventional techniques were compared. It was found that the composites manufactured using the clean pultrusion exhibited lower void and better mechanical properties. A life cycle assessment (LCA) was also performed to compare the environmental impact of the clean and conventional pultrusion processes. The LCA demonstrated conclusively that the clean pultrusion technique offers several environmental advantages over the conventional resin-bath pultrusion. The new pultrusion technique was demonstrated as being a viable method to pultrude composites without using a resin bath.

Microstructural analysis and mechanical property assessment have been carried out on hot isostatically pressed (HIPped) and heat treated samples of RR 1000 powder to assess Net Shape HIPping as a process-route for aero engine components. HIPping led to (Hf,Zr)-rich oxides and carbides on prior particle boundaries (PPBs) which could be coarsened, but not eliminated by changing the HIP procedure. HIPping above the γ′ solvus resulted in coarser grains with serrated boundaries and in the formation of irregular-shaped secondary γ′ and fan-type γ-γ′ structures. Factors which influence the growth and morphology of γ′ particles are considered and it is shown that particle impingement dominates in the formation of irregular γ′ during continuous cooling from supersolvus. Solution treatment near the HIPping temperature led to thermally induced pores (TIP) but lower temperatures avoided TIP and changed the γ′ size, distribution and morphology giving a large volume fraction of finer cuboidal secondary γ′ and medium-sized spherical tertiary γ′.