M.A. / This project examines the phenomenon of subcontracting as it occurs in the gold mining industry in South Africa. The point of departure for the researcher is that subcontracting is not something totally new in the gold mining industry. What seems to be new is the manner in which it is currently used and this could be attributed to variety of factors, which have made reliance on permanent workforce not viable for the employers. Downscaling and large-scale retrenchments have become the order of the day. This happens at a time when there is an unprecedented increase in the number of subcontract workers. This has raised concerns among organised labour who, feel that such form of atypical employment is meant to undermine the gains of the labour movement has gained over the years. Such perception is made even more real by the decline in labour standards. Contractors actively discourage their employees from joining trade unions. Subcontract workers are paid wages as low as R700 a month, while they are forced to work under dangerous conditions. Their terms of contracts are unilaterally changed without any consultation and they can be easily dismissed without any warning, in some cases dismissed for being injured at work. Tensions mount between subcontract and permanent workers as the latter view the former as a threat to their job security. All this makes subcontracting an interesting area of study and this is even made more so by the fact that little has been done to investigate subcontracting in South Africa's gold mines. / Prof. Peter. Alexander

Sodek's Gold is a novel based on individuals the writer has known in the Caribbean who have been placed in fictitious circumstances. Included are social issues, conditions, and dialects found there. The main character, David Sodek, is an Englishman working in the Caribbean who discovers an ancient coin and becomes obsessed with finding more. Sodek's search is impeded by the strongarm Mostyn, but with the help of his friend Elbert he recovers an underwater cache of golden treasure. Elbert is killed. Sodek avenges Elbert's death but ultimately relinquishes the gold and himself to the sea. The theme of the work involves Sodek's obsessive personality as seen in his increasingly pedantic and destructive search, and in his unrealistic belief that money buys freedom. Included between chapters are vignettes comparing the characters and nature, and foreshadowing following events.

Two aspects of gold mineralisation in the Caledonides of the British Isles have been investigated: gold-telluride mineralisation at Clogau Mine, North Wales; and placer gold mineralisation in the Southern Uplands, Scotland. The primary ore assemblage at Clogau Mine is pyrite, arsenopyrite, cobaltite, pyrrhotine, chalcopyrite, galena, tellurbismuth, tetradymite, altaite, hessite, native gold, wehrlite, hedleyite, native bismuth, bismuthunite and various sulphosalts. The generalised paragenesis is early Fe, Co, Cu, As and S species, and later minerals of Pb, Bi, Ag, Au, Te, Sb. Electron probe micro-analysis (EPMA) of complex telluride-sulphide intergrowths suggests that these intergrowths formed by co-crystallisation/replacement processes and not exsolution. Minor element chemical variation, in the sulphides and tellurides, indicates that antimony and cadmium are preferentially partitioned into telluride minerals. Mineral stability diagrams suggest that during gold deposition log bf aTe2 was between -7.9 and -9.7 and log bf aS2 between -12.4 and -13.8. Co-existing mineral assemblages indicate that the final stages of telluride mineralisation were between c. 250 - 275oC. It is suggested that the high-grade telluride ore shoot was the result of remobilisation of Au, Bi, Ag and Te from low grade mineralisation elsewhere within the vein system, and that gold deposition was brought about by destabilisation of gold chloride complexes by interaction with graphite, sulphides and tellurbismuth. Scanning electron microscopy of planer gold grains from the Southern Uplands, Scotland, indicates that detailed studies on the morphology of placer gold can be used to elucidate the history of gold in the placer environment. In total 18 different morphological characteristics were identified. These were divided on an empirical basis, using the relative degree of mechanical attrition, into proximal and distal characteristics. One morphological characteristic (a porous/spongy surface at high magnification) is considered to be chemical in origin and represent the growth of `new' gold in the placer environment. The geographical distribution of morphological characteristics has been examined and suggests that proximal placer gold is spatially associated with the Loch Doon, Cairsphairn and Fleet granitoids. Quantitative EPMA of the placer gold reveals two compositional populations of placer gold. Examination of the geographical distribution of fineness suggests a loose spatial association between granitoids and low fineness placer gold. Also identified was chemically heterogeneous placer gold. EPMA studies of these heterogeneities allowed estimation of annealing history limits, which suggest that the heterogeneities formed between 150 and 235oC. It is concluded, on the basis of relationships between morphology and composition, that there are two types of placer gold in the Southern Uplands: (i) placer gold which is directly inherited from a hypogene source probably spatially associated with granitoids; and (ii) placer gold that has formed during supergene processes.

M.Com. (Economics) / The gold sector has historically made an extremely important contribution to the total external revenue earnings of South Africa. Gold is traded on the international markets at a price which is determined daily through supply and demand and quoted in American dollar terms. South Africa is one of the largest producers of gold in the world and despite this it has no control over the international gold price. Local producers get paid in rands for their production. Because the international gold price is determined in American dollar terms and local producers get paid in rands the exchange rate is extremely important to local gold producers. If the dollar/gold price is compared to rand/dollar gold price in the long term there is a definite pattern. From 1980 to 1990 it can clearly be seen that if the gold price rises or declines the exchange rate has depreciated or appreciated. Since 1990 the dollar/gold price declined steadily until 1993 when it recovered somewhat. The rand exchange rate has not in the past depreciated in relation to the decline in the gold price. A sharp depreciation of the rand since 1990 has been experienced. The question that arises is that has the deviation in the long term relation between the rand/dollar exchange rate and the gold price since 1990 just been temporary in nature or was there a fundamental change? Since 1990 the dollar/gold price has declined from American $383.55 to $324.86 in October 1997. Over the same period the rand has depreciated from 258.17 cent to 470.90 cents for a dollar. Over the whole period the rand has hardly shown signs of appreciation whilst there were sporadic increases in the gold price. Government policy changed in 1990 and the focus moved to inflation control. A sharp increase of nett capital from South Africa was noted since 1990.

A dissertation submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering. Johannesburg, 1990. / The static Rand gold price has put pressure on the South African gold mines to improve efficiency. Superior metallurgical performance and lower costs attributed to column flotation prompted the construction of a pilot plant (238 millimetres by 10 metres) at ERGO, an Anglo American tailings retreatment plant [Abbreviated Abstract. Open document to view full version] / MT2017

The objective of the study was to investigate downscaling in South Africa’s mining industry and the manner in which it was managed with special reference to the gold mining sector. In this regard the study involved literature review, data and information gathering, participating in tripartite stakeholder forums and soliciting opinions from several role players in the industry. Driefontein Gold Mine, one of the largest gold mines in the world, was used as a case study to examine management of downscaling in the gold mining industry. Literature investigation showed that South Africa’s mining industry has always been cyclical and labour was vital for its development. A dichotomy was revealed in the study in that the early years of modern mining were besieged with a continuous shortage of labour; in recent years the opposite is true as the industry is continuously battling with downscaling and shedding of jobs. Historical data shows that the gold mining industry has gone through three periods: the Stable Period (Period 1: 1960-1975); Expansion Period (Period 2: 1976-1987); and Downscaling or Crisis Period (Period 3: 1988-2004). Sufficient evidence was presented to show that the downscaling period was triggered by a combination of political instability of the 1980s and economic factors such as declining gold grades and depressed gold prices. Stakeholders followed a three-phased approach to address negative impacts associated with downscaling. The approach involved holding two tripartite summits; Gold Mining Summit (Phase 1) and Mining Summit (Phase 2) and incorporating recommendations emanating from the summits into the legislative process (Phase 3). At mine level, mines such as Driefontein managed downscaling through a number of initiatives including productivity improvement, restructuring and providing redundant employees with the option of taking extended leave. Economic factors, such as gold grades and ore reserves, suggest that downscaling will continue well into the foreseeable future and will exacerbate the existing negative environmental and socio-economic legacies. It is against this background 3 that international experiences on the management of downscaling were investigated. The study concludes by proposing recommendations and a new strategy to manage downscaling in South Africa’s gold mining industry. The strategy proposes a number of measures that need to be put in place at national, local community and mine levels.

A stable high temperature gold nano-catalyst: synthesis, characterization and application The ability of supported gold nanoparticles to catalyse many reactions even at very low temperatures has spurred a great deal of research into the eld. Reactions such as CO oxidation and NOx reduction have many industrial applications as well as uses in the motor industry for catalytic converters. The interest is both for scienti c as well as economic reasons as gold supplies far exceed all PGM supplies. Scienti cally gold catalysts are able to catalyze reactions from below 0°C, a feat that no PGM catalyst can achieve. The low temperature activity of gold catalysts will reduce the emission of pollutants during start up. Since the discovery and development of gold catalysts one of the most researched topics has been nding ways to stabilise the gold nanoparticles on the support surface. The importance of gold nanoparticle stability is crucial as the catalysts are only highly active if the gold nanoparticles are less than 5 nm in size. A number of companies have worked to develop gold catalysts that are stable for long durations at temperatures over 450°C with no signi cant progress made over the last two decades other than a catalyst produced by Toyota. In this thesis, literature reviews of current support materials as well as synthesis methods are investigated in order to determine reasons for the instability of current gold catalysts. Further, the Mintek Aurolite catalyst is tested and its deactivation mechanisms probed using in-situ VT-PXRD, Rietveld re nement, TEM, HR-TEM, as well as CO oxidation tests. Testing revealed aws in the support structure of the catalyst which resulted in dramatic deactivation. As titania is such a common support material for many reactions in industry as well as being known to be one of the best supports for gold it was chosen as a support material. However, as is revealed, in its current forms and morphologies it is unable to provide the thermodynamically stable and high surface areas that are required for a stable catalyst After the development of a robust and reproducible synthesis method for the deposition of gold and other PGM's a number of supports were tested. These include silica and zirconia as well as titania derivatives such as Degussa P25 and commercial anatase. Initially these supports o er high usable surface areas but after a relatively small amount of time complete deactivation occurs. Reasons for this deactivation are determined and the information gained is used to develop supports that can combat these deactivation processes. Phase pure nano anatase is synthesised which produced a support with an incredibly large surface area compared to the aforementioned supports. The catalyst was able to withstand temperatures over 450°C for longer durations compared to other catalysts exposed to the same conditions. However, the phase conversion of the anatase to its thermodynamically stable form rutile once again deactivated the catalyst with time. Finally a rutile nanosupport is developed with the desired morphology and thermodynamic stability needed for high temperature applications. The catalyst is able to withstand temperatures over 550°C for more than 200 hours as well as still being active after exposure to 810°C. The industrial Aurolite catalyst showed complete deactivation after just 12 hours at 500°C. The catalyst produced in this thesis has been shown to be one of the most stable and thermally resistant gold catalysts in the world.

Zeolite catalysts were prepared by carrying out an ion-exchange process of transition metals and impregnation to incipient-wetness method of metal catalyst using a chlorine free gold precursor, KAu(CN)2. The instability of Au/Y (3.74wt%Au) resulted in low CO oxidation activity (~ 18 % conversion at 450 0C), suggesting that the reduced gold metal atoms are bound to the zeolite by a weak interaction. This is subject to migration within the passages of the zeolite during use. The presence of proton stabilized most of Au clusters (electron deficient species) within the HY zeolite, resulting in small amounts of gold species migrating to the outer surface. Interestingly the CO oxidation activity of Au/HY is half that of Au/Y, which clearly indicate that the presence of metallic gold plays a significant role during CO oxidation. The loading of Au/M-Y (M = Ni2+, Fe3+, Co2+ or Cr3+) were varied from 1.67- 7.48wt%Au and from 1.76-5.45wt%M. Modification of this Y structure with transition metals has been found to be beneficial for both activity and stability of smaller gold clusters, by strengthening the interaction between gold and zeolite exchange sites and by large magnitude in maintaining the dispersion of gold. This suggests that the unreduced chromium ions function as a chemical anchors for reduced Au metal and that the reduced atoms of gold may form small clusters with the anchoring metal. TPR profile has confirmed that the introduction of 1.67wt%Au on Fe-Y (1.88wt%Fe) increased the stability of Fe ions as stabilizer metal. However, as the gold loading of Au/Fe-Y catalyst increases the TPR profile shows that the stability of Fe ions decreases and hence the activity of catalysts. An increase in transition metal content, above 1.88wt%Fe was found to lower the CO oxidation activity. A TPR profile has confirmed that as the reduction potential became more negative, the activity of supported Au increases following the sequence: Ni2+, 0.23 << Fe3+, -0.41 < Cr3+, -0.56. The estimated particle sizes of gold by X-ray diffraction were found to be ~ 12 nm for Ni2+, ~ 7 nm for Fe3+, and ~ 5 nm for Cr3+ stabilized metal. Samples of Au/HY (3.77wt%Au) have been prepared by an ion-exchange method using Au(III) ethylenediamine complex-ions, [Au(en)2]3+. Following a pretreatment in an O2 atmosphere, the catalyst showed the existence of an induction period before reaching a steady state activity; suggesting the need for activating gold prior to catalyzing CO oxidation reaction. As-prepared catalyst contained 85% of gold in the Au3+ valence state as confirmed by Mössbauer spectroscopy. The catalyst was treated with various reducing agents (such as NaBH4); to yield stable and active smaller gold clusters (< 2 nm) inside the HY cavities, as revealed by X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD) and Uv- Vis Spectrophotometer. DRIFTS revealed that electron-deficient particles (Auó+- CO species) of gold clusters, inside the HY framework and in contact with protons are active species for CO oxidation. CO activity and formation of smaller gold clusters depends on the nature and molar ratio of reducing agents, and the source of gold. The induction period observed for unreduced Au catalyst is a slow step in the activation of gold active sites. Treatment of Au/Y (3.46wt%Au) with sodium borohydride enhanced the activation of gold active species and hence improves the catalytic activity. The NaBH4 treated Au/Y (3.73wt%Au) catalyst has shown, for the first time, activity of approximately 28% CO conversion. The catalyst showed almost the same activity and induction period as that of the untreated Au/HY (3.77wt%Au) catalyst, which leaves much to be investigated about the behaviour of Au on Y zeolite upon treatment with a proper reducing agent. The protons have been found to stabilize the smaller Au nanoparticles within the zeolite cavities. The modification of zeolite-Y was carried out by treatment with different alkali metal nitrates such as LiNO3, NaNO3 and KNO3 before introducing gold from different sources, (i.e. gold ethylenediamine complex ion, Au(en)2Cl3; chloroauric acid, HAuCl4; or potassium dicyano aurate, KAu(CN)2 complex). The CO oxidation activity of the catalysts was found to depend on the nature of the gold source and on the type of alkali metal nitrate used. The order of activity was as follows: HAuCl4 >> KAu(CN)2 > Au(en)2Cl3. It was found that the activity of catalysts prepared by deposition of Au from an aqueous solution of chloroauric acid on Na-modified zeolites-Y, increased as a result of an increase in the amount of Au deposited as confirmed X-ray fluorescence spectroscopy (XRF). The Kmodified zeolite-Y had a smaller amount of Au deposited (i.e. Au/KY, 0.454wt%Au; Au/NaY, 0.772wt%Au and Au/LiY, 0.212wt%Au) and hence the CO oxidation activity was lower than that of Na-modified zeolites-Y. Thus, the order of the catalytic activity is as follows: Na > K > Li. The XRD studies have revealed that metallic gold particles sizes do not depend on the nature of alkali metal nitrates used to modify the zeolite-Y surface and the zeolite-Y crystallinity has been maintained. Monometallic Au/NaY (0.772wt%Au, treated with NaNO3) was found to be active in ethylene hydrogenation with ~5% conversion. Treatment of catalysts with NaBH4 was found to lower the catalytic activity of the catalysts, contrary to activities observed on CO oxidation and these concluded that cationic gold are responsible for the observed activity. The activity was found to depend on the source of Au used, and the order is as follows; HAuCl4 >> KAu(CN)2 > Au(en)Cl3. Bimetallic catalysts of Au/M-Y (where Au represent gold from KAu(CN)2, and M = Ni2+, Fe3+, or Cr3+) were found to be more active compared to monometallic catalysts due to promotional effect of transition metal. The order of activity of the bimetallic system at 260 0C was as follows; Ni2+ >> Fe3+ > Cr3+, and at 150 0C, was Ni2+ >> Cr3+ > Fe3+, contradicting the order of activity observed on CO oxidation. Formation of carbonaceous deposits on the surface of the catalyst at temperature higher than 260 0C has been confirmed. Cu modified Au/TiO2 (anatase, 200m2/g) has been prepared by incipient-wetness method by either introducing the modifier, before or after Au loading. Such catalysts were found to give high and stable activity for the water-gas shift (WGS) reaction, when compared to unmodified Au/TiO2 catalysts. It has been suggested that an increase in activity on modified Au/TiO2, is mainly due to the existence of a synergetic interaction between Cu and Au, since the activity of both Cu/TiO2 and Au/TiO2 is lower than that of bimetallic system. The presence of nitrates on Cuc-Au/TiO2 (c Cu precursor is Cu(NO3)2*2.5H2O) has been found to be detrimental to the activity of Au on TiO2; due to the poisoning of Au active sites and enhancement of Au agglomeration by NO2 - formed during the reaction. An increase in Cu loading lowers the activity of Au. A XANES spectrum has confirmed that gold exists as either Au+/Au0 during WGS reaction and Cu exists as copper ions (Cu+/Cu2+) before and during WGS reaction. Formation of bimetallic particles was not detected by EXAFS data analysis. The observed effects are interpreted as a mutual influence of gold and copper ions and reduced species of gold and copper due to their competing for ion exchange sites. Cu has no promotional effect on low temperature CO oxidation and on preferential CO oxidation in excess of hydrogen.

Chak, Chun Pong. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 190-202). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Nanoparticle toxicity has become a major topic of interest due to the inevitable exposure of these nanomaterials to both humans and the environment. Nanotechnology is a rapidly growing industry with diverse material resources and an extensive market for commercialization and introduction of nanomaterials into consumer products. The problem with this flourishing technology is that it has far outgrown research based on the safety and toxicity of the nanomaterials, which in bulk are generally nontoxic. The need for research in determining the toxic effects on cells and the implications it may have on the environment have grown but the different techniques, cell systems and nanoparticles employed are generally to diverse and conflicting in overall results that determination toxicity is nearly impossible. The need for a universal technique to study the interaction of nanoparticles with cells and decouple the molecular effects (chemical properties) from the“nanospecific" effects (including size, concentration, surface charge, functionality and polarity) is apparent. It is additionally necessary to determine the mechanisms associated with nanoparticle-induced cytotoxicity in order to better understand the problems posed to both human and environmental health and then develop new safer nanoparticles. Therefore, the focus of this study is to determine the nano-specific (physical) properties, including size and functionalization that cause toxicity, specifically through interaction with a cell membrane. A supported lipid bilayer (SLB) composed of L-α-phosphatidylcholine (egg PC) was used as a model cell membrane to test the effects of 2, 5, 10 and 40 nm gold nanoparticles (AuNPs). Given the imminent exposure of nanoparticles to the environment it is important to determine how nanoparticles would behave in the presence of natural organic matter or polymers which are naturally present in environmental systems. Poly(methacrylic acid) (PMA) can be used to represent the polymers normally found in the environment. AuNPs were diluted in PMA in order to simulate fundamental environmental conditions. Analysis was done using a quartz crystal microbalance with dissipation (QCM-D), which measures the frequency (f) and dissipation (D) changes directly associated with mass and conformation changes of the SLB. Different overtones for f and D allow for theoretical interpretation of changes correlated to different layers of the membrane. The 2 and 5 nm particles were found to interact strongly with the lipid bilayer by adsorbing to and/or partially/completely penetrating into the lipid bilayer presumably due to a hydrophobic coating caused by PMA adsorption to the NP surface. The penetration caused a much more rigid membrane due to higher lipid packing caused by nanoparticle addition. The 10 and 40 nm particles interaction with the bilayer were not affected by the presence of PMA. Both AuNP sizes removed mass from the membrane with losses similar in de-ionized water and PMA solution. Removal of membrane mass (lipids/hydration) caused a more flexible membrane. It was determine that sized is the limiting factor for nanoparticle solubilization into the membrane. It can be concluded from the results that size coupled with natural organic matter affects the cytotoxicity of the nanoparticles to the membrane. A study was done with 12 nm functionalized AuNPs in the presence of humic acid, a well-known and more complex and realistic model for natural organic matter. A PC lipid bilayer was used to simulate a model cell membrane and QCM-D techniques were utilized in the determination of toxicity and mechanistic interaction of nanoparticles with a lipid bilayer. Functionalized AuNPs were shown to decrease the rigidity of the lipid bilayer by increasing the dissipation and decreasing the mass associated with the adsorbed film (SLB). The presence of humic acid stabilized the nanoparticles and provided increased electrostatic repulsion which resulted in decreased mass losses from the membrane and much smaller decreases in membrane rigidity. It was concluded that presence of humic acid reduces the effects of functionalized nanoparticle interaction with a lipid bilayer. These results may mean that natural organic matter has the ability to reduce the cytotoxic effects of nanoparticles released into the environment. Overall, the QCM-D was found to provide valuable information regarding the possible toxic properties and mechanisms in which different gold nanoparticle interact with a supported lipid bilayer under environmental conditions. The information provided by the studies performed has shed much light on the interaction of gold nanoparticles with a supported lipid bilayer in the presence of model natural organic matter. The experiments done in this study are the first steps towards developing an assay with the ability to determine the toxic physical properties and mechanisms by which nanoparticles interact with lipid bilayers will greatly aid in development of non-toxic nano-materials. The technology and techniques used in this study will greatly improve the field by solidifying one technique to use in the quantitative approach studying nanoparticle/cell interactions. The use of AFM techniques in conjunction with the QCM-D would be highly beneficial by facilitating better understanding of the exact mechanisms by which nanoparticles induce cytotoxicity.