In this thesis I present three papers on the Economics of the base metals industry. The thesis studies production, trading, and investment in the base metals industry, and thus explains some phenomena of the industry in an international context. Using the features of the base metals industry such as the practices in production and trading, physical properties, geology of the deposits and so on, we build theoretical models to simulate the behavior of the industry. In Chapter One, we study the determinants and the trend of base metals prices over time by an equilibrium model of supply and demand. Because the different types of natural resources exhibit different patterns of price changes in history, we particularly simulate the long run equilibrium to study the impacts of the determinants for base metals prices. The Cobb-Douglass production function on the supply side allows substitution among production factors. The demand function for base metals from the economy is also derived. In the long run, equilibrium of aggregate supply and demand determines the systematic price trend. We show how trends of base metals prices depend on technological progress, resource scarcity, natural resource tax, and the interest rate. Assuming constant returns to scale in base metals production, the price elasticity of the supply of base metals is relatively small. Interestingly, a high natural resource tax leads to a high price but low rate of price change over time. On the supply side, the decline of base metals relative prices can thus be explained by the inverse supply functions. On the demand side, the relative price is also declining over time as we see the implications of the inverse demand functions and our numerical illustrations. By solving the equilibrium condition, we show that the economic rent of base metals minerals in reserve may decline over time, or even not be valuable in future. The price elasticities of supply and demand are calculated and decomposed into specific effects. These are systematic components of base metal price changes in the world market. Chapter Two deals with the fluctuations in the prices of base metals. We consider the price in the short run as an equilibrium of trade. If the long run equilibrium regulates the prices and sets them in a stabilization, then the fluctuations in price are caused by the trade and speculative activities. By simulating speculative activities and optimizing the utility of agents in international exchanges, we show that the price fluctuations are the response to risk preferences of agents and the scale of international exchanges. We find out the critical point of production investment, which depends on the market demand, profitability of the metal industry, and the distribution of base metal minerals in nature. In the specific case of the industry versus the market condition when the uncertain production is above the critical point, the price of base metal fluctuates more or less according to the number of producer offers in base metal exchanges, the speculative activities, and risk preferences of agents. In contrast, if the investment level of the base metals industry in uncertain production is below the critical point, the effects of base metal exchanges scale to the price are in the reverse direction. The comparative statics inequalities are derived to clarify the responses of the price to the risk preferences of agents and scale of the international exchanges. Hence, the non-systematic changes of base metals prices in international exchanges are explained. Chapter Three studies the impact of the industrial and commercial processes on investment decisions in the base metals industry. The investment decisions of investors in the primary capital market and the stock price in the secondary capital market reflect properties of the base metals industry in capital markets. We present a model of investments, which is a two stage game that incorporates Hall-Jorgenson neoclassical investment analysis and properties of the base metals industry. The paper presents a set of explanatory parameters for the properties of base metal stocks and analyzes the investment decisions. We define the industry factor and explain the empirical observations on the beta coefficient of base metal stocks. The relationships between stock prices and base metals prices are clarified using the geology of base metals deposits. The results show that there is a strong impact of the industry factor on the volatility of base metal stock prices. Economies of scale in the mining industry lead to different effects of tax policy and output prices on investment decisions. We support conclusions of the model by evidence in the base metals industry. There are policy implications that are derived from the equations of the optimal investment. Key words : Base Metals, Price Fluctuations, Price Trends, Risk Aversion, Metals Industry, LME, International Exchange, Metal Stocks, Investment.

The massive sulphide deposits at Areachap and Kantienpan Cu-Zn Mine are hosted by a ~1600 Ma old volcano sedimentary succession known as the Areachap Group, in the eastern part of Namaqua Metamorphic Province, South Africa. The deposits were affected by a complex deformation and metamorphic history and represent examples of upper amphibolite to granulite grade metamorphosed volcanic-hosted massive sulphide (VHMS) deposits. The host rocks of both ore deposits are peraluminous-gneisses and the dominant sulphide minerals in the ore zone are pyrite, pyrrhotite sphalerite, and chalcopyrite and trace amounts of galena. Other ore related minerals include barite and anhydrite. The metamorphic minerals in the alteration zones at the Areachap and Kantienpan VHMS deposits are characterized by the presence of plagioclase, almandine and pyrope, enstatite and clinoenstatite, cummingtonite and gedrite, cordierite, sillimanite, and retrograde chlorite and chamosite. Lithogeochemical methods are widely used in exploration geochemistry to identify the primary alteration zones related to VHMS mineralization, as these zones are often exposed, while the massive sulphide ore body itself may be concealed. Especially in areas that were not affected by high grade metamorphism and intensive deformation. Some of these methods include the variation in the relative abundance of major element concentrations throughout the rock successions, mineral chemistry of silicates and spinel minerals near the ore zone, and normative compositions of the rock successions. However, the application of these methods is limited by complex geology in regional metamorphic terranes, such as the Namaqua Metamorphic Province. Therefore, in addition, three of the more advanced lithogeochemical approaches, known as the Isocon method, the Box Plot and Pearce Elemental Ratios, are combined here and adapted for application in such regions. Based on the mineral chemistry, it is evident that plagioclase is more Ca-rich adjacent to the ore zone, pyroxene has the highest relative Mg* ratio (Mg* ratio =100 x cationic ratio of Mg / (Mg + Fe + Ca)), the almandine and pyrope components of garnet are high and the spessartine and grossular components are low. In addition, the Mg-rich variety of mica (phlogopite) is more common near the ore zone and the peraluminous nature of the footwall zone is revealed by the presence of gahnite. Cordierite and retrograde chlorites show the highest Mg#’s (Mg# = Mg/ (Mg + Fe)) in the ore zone. In addition to the above, Pearce Element Ratio analyses of cordierite, pyroxene and garnet may be used to define proximity to sulphide mineralization. Geochemically, the ore zone and alteration zones at Areachap and Kantienpan VHMS ore deposits display a high peraluminous ratio (Al2O3 / (Na2O+K2O+CaO)) confirming the peraluminous nature of these zones as indicated by the mineral chemistry discussed above. The intervals identified in sampled borehole core with low CaO and Na2O and with high MgO and K2O contents represent the alteration zone in the original footwall rocks of the deposit. Isocon studies have shown that the alteration zones at the Areachap and Kantienpan deposits are enriched in Mg, Fe (total), S, Zn, Si, Co and F and depleted in Na, Ca, Sr, Ni, V and La. Elements that behaved relatively immobile include Zr, Ti, P, Mn, Al, Y, and U. The box plot, alteration index versus the chlorite-carbonate-pyrite index, was originally proposed to illustrate the combined effects of hydrothermal and diagenetic alteration and is based on characteristic primary mineral reactions in regions not affected by regional metamorphism. It is demonstrated here that these primary mineral reactions are preserved in a unique set of metamorphic minerals, and that the box plot can be modified for high-grade metamorphic rock types. When samples with very high Mg contents (MgO>>K2O, AI>90% and CCPI>98%) are plotted in the box plot they may be classified as representative of anomalous areas that are highly prospective. Samples with high Mg contents (MgO>K2O, AI>64% and CCPI>93%) may be considered representative of areas that may be classified as of moderate priority in an exploration programme. The findings of the mineral chemical and geochemical investigations of the footwall alteration at the Kantienpan, Areachap and Prieska Cu-Zn ore bodies are used to define various statistical factors. The applicability of these factors in lithogeochemical exploration is demonstrated by calculating the respective factor scores for a regional lithogeochemical data set. It is demonstrated how these factors could be used to identify samples collected from localities that are highly prospective for the discovery of concealed VHMS style mineralization. Based on the statistical analyses of the regional data set, the altered rocks may be distinguished from the metapelitic rocks by their high scores for the alteration factor and low scores for the peraluminous factor. The peraluminous rocks may be separated from the hornblende-gneisses by their high scores for the peraluminous factor, and from the amphibolites by their very low ortho-amphibolite factor scores and high peraluminous factor scores. The variation, of trace elements in the surface calcrete layer that conceals the mineralization in the studied areas, displays the geochemical signature of mineralization, but the concentrations of Cu, Zn and Pb are much lower at and near surface and increase down depth within the profiles. The absolute concentrations and peak to background ratios of the elements of interest at the surface therefore depend on the thickness of the underlying calcrete layer in the area. Two methods, a total analysis (x-ray fluorescence, XRF) and partial extraction (NH4EDTA solution), were applied in to evaluate results, which would be successful and commercially viable in a general exploration programme, using regolith samples. The results of the two methods above were then compared to another patented partial extraction method (mobile metal ion, MMI) on a data set previously reported on by Rossouw (2003). At Kantienpan, where the sand cover is very shallow to absent, dispersion appears to be more related to the secondary redistributions of gossaniferous clasts, than to dispersion of mobile metal ions on the surface of sand particles. The XRF method shows a wider dispersion halo here than methods based on partial extraction. Whereas, at Areachap, where a relatively thick sand (approximately one metre) covers the calcrete layer, partial extraction (based on a NH4EDTA solution extraction) results in a larger, recognizable, dispersion halo than that detected by XRF. The MMI results show a larger span for Zn, followed by NH4EDTA and finally XRF. For Cu, the NH4EDTA method exhibits the largest span followed by XRF and then MMI. The anomalous Cu, Zn and Pb contents extracted by partial extraction methods from the wind blown sand deposits indicate that these elements were derived from the ore minerals related to the massive sulphide deposits. However, Mn and Fe contents analysed by XRF also show high values that could not be only related to derivation from massive sulphide ores. Some of the high concentrations of these elements in the sand cover is ascribed to the weathering of other iron-rich rock forming minerals. / Thesis (PhD (Geology))--University of Pretoria, 2006. / Geology / unrestricted

The investigation of reactor pressure vessel (RPV) material from the decommissioned Greifswald nuclear power plant representing the first generation of Russian-type WWER-440/V-230 reactors offers the opportunity to evaluate the real toughness response. The Greifswald RPVs of 4 units represent different material conditions as follows: • Irradiated (Unit 4), • irradiated and recovery annealed (Units 2 and 3), and • irradiated, recovery annealed and re-irradiated (Unit1). The recovery annealing of the RPV was performed at a temperature of 475° for about 152 hours and included a region covering ±0.70 m above and below the core beltline welding seam. Material samples of a diameter of 119 mm called trepans were extracted from the RPV walls. The research program is focused on the characterisation of the RPV steels (base and weld metal) across the thickness of the RPV wall. This report presents test results measured on the trepans from the beltline welding seam No. SN0.1.4. and forged base metal ring No. 0.3.1. of the Units 1 2 and 4 RPVs. The key part of the testing is focussed on the determination of the reference temperature T0 of the Master Curve (MC) approach following the ASTM standard E1921 to determine the facture toughness, and how it degrades under neutron irradiation and is recovered by thermal annealing. Other than that the mentioned test results include Charpy-V and tensile test results. Following results have been determined: • The mitigation of the neutron embrittlement of the weld and base metal by recovery annealing could be confirmed. • KJc values of the weld metals generally followed the course of the MC though with a large scatter. • There was a large variation in the T0 values evaluated across the thickness of the multilayered welding seams. • The T0 measured on T-S oriented SE(B) specimens from different thickness locations of the welding seams strongly depended on the intrinsic structure along the crack front. • The reference temperature RT0 determined according to the “Unified Procedure for Lifetime Assessment of Components and Piping in WWER NPPs - VERLIFE” and the fracture toughness lower bound curve based thereon are applicable on the investigated weld metals. • A strong scatter of the fracture toughness KJc values of the recovery annealed and re-irradiated and the irradiated base metal of Unit 1 and 4, respectively is observed with clearly more than 2% of the values below the MC for 2% fracture probability. The application of the multimodal MC-based approach was more suitable and described the temperature dependence of the KJc values in a satisfactory manner. • It was demonstrated that T0 evaluated according to the SINTAP MC extension represented the brittle fraction of the data sets and is therefore suitable for the nonhomogeneous base metal. • The efficiency of the large-scale thermal annealing of the Greifswald WWER 440/V230 Unit 1 and 2 RPVs could be confirmed.

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: See item for full text / AFRIKAANSE OPSOMMING: Sien item vir volteks

Thesis (MScEng)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: In a first stage atmospheric leach at the Lonmin Marikana base metals refinery, nickel-copper-iron-sulphur Peirce Smith converter matte is leached in recycled electrolyte from the electrowinning section. The electrolyte contains sulphuric acid, copper and nickel sulphates, and a small amount of iron sulphate. The converter matte contains mostly nickel, copper and sulphur (typically 48 %, 28 % and 23 %, respectively), but also minor amounts (<5 %) iron and cobalt. The matte also contains platinum group elements (PGEs) and other precious metals totalling 0.2 – 0.7 % (platinum, palladium, iridium, rhodium, ruthenium, osmium and some gold). The predominant mineral phases are heazlewoodite, chalcocite and a nickel-copper alloy phase, as well as some entrained slag and spinel minerals. The purpose of the first stage leach is to extract nickel, while simultaneously precipitating copper and PGEs contained in the recycled electrolyte. Nickel, cobalt and iron are leached by acid and oxygen. Copper is precipitated by a redox reaction in which copper ions oxidise nickel from the matte. The purpose of this study was to determine the effects of key variables on the performance of the first stage leach (specifically on the removal of PGEs and copper from solution and the overall extraction of nickel) and to improve fundamental understanding of these effects. Batch leaching tests were carried out to investigate the effects of the following factors: availability of oxygen, initial acid concentration, initial copper concentration, iron endpoint (iron content of the matte), solids/liquid ratio and stirring rate. Liquid samples were analysed with Atomic Absorption Spectroscopy (AA) to determine leaching kinetics. Characterisation of solid samples from leach tests by quantitative X-Ray diffraction (XRD) and scanning electron microscopy with an energy dispersive system (SEM-EDS) helped to improve understanding of the leaching mechanism. The oxidative leaching mechanism entails an initial period in which the alloy phase is leached by acid and oxygen, while copper reacts with the nickel-copper-alloy and heazlewoodite phases (which react galvanically with each other) to form a chalcocite precipitate. In a second reaction period, heazlewoodite was transformed to millerite by acid leaching and the particle structure became more porous. The rate of copper precipitation and nickel extraction were faster during the second reaction period than the first reaction period. Some copper leaching occurred once the leachable nickel (60 – 70 %) had been dissolved, provided that the solution was strongly acidic (pH < 2). The non-oxidative leaching mechanism entails a galvanic interaction, between the nickel-copper-alloy and heazlewoodite phases, in which nickel is leached from both phases and copper is precipitated as chalcocite. Leaching by acid was negligible in most non-oxidative tests. An initial fast period of copper precipitation was followed by a second slower period. The decrease in reaction rate can probably be linked to the decreasing availability of the nickel-copper-alloy phase. During non-oxidative leaching, the particle structure remained mostly intact. Copper precipitation kinetics under non-oxidative conditions was found to be slower than under oxidative conditions. The faster copper precipitation kinetics under oxidative conditions is most likely caused by an increase in porosity and reaction area as nickel is leached from the matte by acid and oxygen. The initial acid concentration, solids/liquid ratio and Fe-endpoint were the most important factors determining reaction kinetics under oxidative conditions. Low initial acid concentrations (37 g/L) and a high solids/liquid ratio improved the extent of copper precipitation. Nickel extraction was enhanced by low solids/liquid ratios and high initial acid concentrations (74 g/L). Nickel extraction was significantly less (56 % less in one instance) when leaching high iron mattes (5.7 % Fe) rather than low iron mattes (< 1 % Fe). Copper precipitation was initially faster when leaching a high iron matte, but slower nickel leaching from high iron mattes led to an excess of available acid, which resulted in copper being leached. The results suggest that high iron mattes will lead to poor copper and PGE precipitation in the first stage leach and also to lower nickel extractions. Consequently, Peirce Smith converting at the plant must be carefully controlled to avoid high iron mattes. Under non-oxidative conditions, the solids/liquid ratio and Fe-endpoint were the most important factors. The rate of copper precipitation was faster when a high iron matte was leached, so that a higher percentage copper was precipitated and more nickel was extracted from the matte. / AFRIKAANSE OPSOMMING: As ‘n eerste stap in die Lonmin Marikana basis-metale veredelingsaanleg word nikkel-koper-yster-swawel Peirce-Smith-converter-mat geloog in elektroliet wat hersirkuleer word vanaf die aanleg se koper-elektroplaterings-afdeling. Die loging word by atmosferiese druk uitgevoer. Die elektroliet bevat swawelsuur, koper- en nikkel-sulfate en ‘n klein hoeveelheid ystersulfaat. Die mat bevat hoofsaaklik nikkel, koper en swawel (tipies 48 %, 28 % en 23 %), maar ook klein hoeveelhede (< 5 %) yster en kobalt. Verder maak Platinum Groep Elemente (PGE’s) en ander waardevolle metale (platinum, palladium, iridium, rhodium, ruthenium, osmium en goud) 0.2 % tot 0.7 % van die massa van die mat uit. In terme van minerale bestaan die materiaal hoofsaaklik uit heazlewoodite, chalcocite en ‘n nikkel-koper allooi fase, asook slak en spinel minerale, wat tydens Peirce-Smith-converting weens meesleuring in die mat rapporteer. Die doel van die eerste stadium loog is om nikkel op te los, terwyl koper en PGE’s wat in die elektroliet voorkom presipiteer moet word. Nikkel, kobalt en koper word geloog in reaksies met suurstof en swawelsuur. Koper word presipiteer deur middel van ‘n redoks reaksie waarin koper-ione nikkel in die mat oksideer. Die doel van hierdie studie was om die effekte van sleutelveranderlikes op die proses te bepaal (spesifiek hoe nikkel-loging en koper presipitasie affekteer word) en om fundamentele begrip van die veranderlikes en hul effekte te verkry. Lot loogtoetse is uitgevoer op ‘n laboratorium-skaal en die effekte van die volgende faktore is ondersoek: beskibaarheid van suurstof, begin suurkonsentrasie, yster eindpunt (die ysterinhoud van die mat), vastestof/vloeistof verhouding en die roertempo. Vloeistof monsters geneem tydens loogtoetse is geanaliseer met behulp van Atoom Absorpsie Spektroskopie (AA) om kinetika te bepaal. Vastestof monsters is ook geneem tydens loogtoetse en kwantitatiewe X-straal diffraksie (XRD), asook skanderings-elektron-mikroskopie met ‘n energie dispersie sisteem (SEM-EDS) is gebruik om die materiaal te karakteriseer en die logingsmeganisme te verduidelik. Die oksidatiewe logingsmeganisme behels ‘n aanvanklike periode waartydens die allooi fase geloog word deur suur en suurstof, terwyl koper presipiteer om chalcocite te vorm as gevolg van ‘n reaksie waarin galvanise interaksie tussen die nikkel-koperallooi en heazlewoodite fases ‘n belangrike rol speel. In ‘n tweede reaksie periode is heazlewoodite geloog deur suur om millerite te vorm. Tydens hierdie tweede fase het die partikel struktuur meer porieus geword. Die tempo van koper presipitasie en nikkel loging was vinniger tydens die tweede reaksie periode as tydens die eerste. Koper is geloog indien die oplossing baie suur was (pH < 2) en die loogbare nikkel (60 – 70 %) reeds opgelos het. Die nie-oksidatiewe logingsmeganisme behels galvaniese interaksie tussen die nikkel-koper-allooi en heazlewoodite fases, wat lei tot koper presipitasie as chalcocite. Loging deur swawelsuur was onbeduidend. ‘n Aanvanklike vinnige periode van koper presipitasie tydens nie-oksidatiewe toetse is gevolg deur ‘n tweede stadiger periode. Die afname in reaksietempo kan waarskynlik verklaar word deur die afnemende beskikbaarheid van die nikkel-koper-allooi fase. Tydens nieoksidatiewe loging het die partikel struktuur redelik onveranderd gebly. Koper presipitasie kinetika in nie-oksidatiewe toetse was stadiger as in oksidatiewe toetse. Die belangrikste faktore wat kinetika in oksidatiewe toetse beïnvloed het was die suurkonsentrasie, vastestof/vloeistof verhouding en die yster-eindpunt. Lae beginsuurkonsentrasies (37 g/L) en ‘n hoë vastestof/vloeistof verhouding het gelei daartoe dat meer koper uit die elektroliet herwin is. Nikkel ekstraksie was hoër indien die vastestof/vloeistof verhouding laag was en die begin suurkonsentrasie hoog (74 g/L). Nikkel ekstraksie was beduidend laer (56 % laer in een geval) wanneer hoë-yster mat (5.7 % Fe) geloog is, eerder as lae yster mat (< 1 % Fe). Wanneer ‘n hoë yster mat geloog is, was koper presipitasie aanvanklik vinniger, maar weens stadige nikkel-ekstraksie-tempos was ‘n oormaat van suur beskikbaar sodat koper uiteindelik geloog is. PGE presipitasie is ook nadelig beïnvloed wanneer koper geloog is en veral tydens toetse met hoë yster mat. Die mees belangrike faktore wat nie-oksidatiewe loging beïnvloed het was die vastestof/vloeistof verhouding en die yster-eindpunt. Die tempo van koper presipitasie was vinniger in toetse met ‘n hoë yster mat, sodat ‘n hoër persentasie koper presipiteer het en meer nikkel opgelos het wanneer ‘n hoë yster mat geloog is.

The aim of this study was to verify the behavior of five brands of NiCr alloys, indicated to porcelain fused to metal restorations, comparing the castability with the ability of reproducing the thin edges of restoration margins. The samples were divided in five groups, each one for one brand, with ten repetitions for castability test and ten for edge reproduction, in a total of 100 specimens. A carbon free phosphate bonded investment was used for all casting procedures. Optical microscopy was used to investigate the microstructure of the specimens obtained with two of the alloys, those which have shown better results. Statistical analysis stated that the commercial brand Tilite showed both better castability and edge reproduction. / O objetivo desta pesquisa foi verificar o desempenho de cinco ligas de níquel-cromo para restaurações de metalocerâmicas, comparando a fluidez com a capacidade de cópia da borda fina das restaurações. Os corpos-de-prova foram divididos em 5 grupos um para cada liga, sendo realizado dez corpos-de-prova para o teste de fluidez e dez corpos-de-prova para o teste da cópia da borda, totalizando 100 corpos-de-prova. Um revestimento de fosfato sem carbono foi usado para todas as inclusões e fundições. Em seguida foram submetidos a microscopia óptica, para se observar a microestrutura das duas ligas que obtiveram os melhores desempenhos. Os resultados, após análise estatística, demonstraram que a liga Tilite apresentou a melhor fluidez e melhor cópia da borda.

Late-stage fissure-filling ore at the world class Bingham Canyon, Utah, porphyry copper deposit has long been recognized, but poorly studied. Physical and chemical characterization of the Pb-Zn-Cu-Ag-Au mineralized fissures in the porphyry-epithermal transition zone provides insight into the origin, timing, and controls of ore deposition. These sheared sulfide-rich fissures are dominated by pyrite and multiple generations of quartz, with lesser amounts of other sulfides and gangue minerals. Au (0.27 to 4.61 ppm) provides the most value to the ore in the transition zone. Host rocks include Eocene monzonite and Paleozoic limestone and quartzite"”all of which can contain economic ore bodies. Associated alteration is predominantly sericitic and argillic. Mineralization into the wall rocks is restricted, not exceeding 1.5 m from the fissure margins. Mineral assemblages vary with distance from the center of the main Cu-Mo deposit and the modal abundances are dependent on host rock. The appearance of both galena and sphalerite (and tennantite to an extent) mark the transition from a porphyry to an epithermal environment. This is accompanied by an increased concentration of chalcophile trace elements in sulfides as determined by EMPA and LA-ICP-MS. Significant hosts of Ag include galena and tennantite, while Cu is hosted primarily in chalcopyrite, tennantite, and sphalerite. Gold does not appear to be hosted in solid solution, but may be focused along fractures or inclusions in pyrite. δ3434S values of fissure pyrite has a narrow range (+2.3 to 3.4‰), while δ18O of quartz is more variable and high (+11.5 to 14.0‰) relative to typical hydrothermal quartz. This can be explained by increased fractionation at lower temperatures in the magmatic fluids, which could have additionally mixed with exchanged 18O-rich meteoric water. Ore grades improve with distance from the center of the deposit; however, this is accompanied by higher concentrations of elements (Pb, As, Bi, etc.) undesirable for downstream processing. The mineralized fissures were created sequentially throughout the formation of the deposit. Initial joints probably formed as a result of the intrusion of a barren equigranular monzonite. The NE orientation of the joints was controlled by the regional stress field, which is more apparent distal to the center of the deposit. A quartz monzonite porphyry then intruded, dilating the joints to allow precipitation of quartz and then pyrite during the Cu-Au-stage of mineralization in the main ore body. After dike-like intrusions of latite porphyry and quartz latite porphyry intruded, galena, sphalerite, and pyrite precipitated to form the Pb-Zn-Ag mineralization. This was followed by late precipitation of chalcopyrite and tennantite (and likely Au mineralization).

Thesis (MBA (Business Management))--University of Stellenbosch, 2009.

Ziel des BMWi-Fördervorhabens 1501393 ist es, durch den Einsatz von Untersuchungsmethoden auf der nm-Skala einen Beitrag zur Aufklärung von Flusseffekten und von Late-Blooming-Effekten in bestrahlten RDB-Stählen zu leisten. Zur Untersuchung dieser Effekte wurde auf RDB-Stähle deutscher Reaktoren aus zwei bei der AREVA GmbH abgeschlossenen Vorhaben zurückgegriffen. Die Auswahl der Grundwerkstoffe und Schweißgüter erfolgte so, dass sich optimale Voraussetzungen für das Erreichen des Gesamtziels des Vorhabens ergeben. Die ausgewählten Untersuchungsmethoden umfassen mit der Neutronenkleinwinkelstreuung, der Atomsondentomographie und der Positronen-annihilationsspektroskopie solche Techniken, die die nm-skaligen bestrahlungsinduzierten Defekt-Fremdatom-Cluster bestmöglich und in komplementärer Weise zu detektieren und zu charakterisieren gestatten. Es wurde ein Flusseffekt auf die Größe der bestrahlungsinduzierten Fremdatomcluster, jedoch nicht auf den Volumenanteil und die mechanischen Eigenschaften gefunden. In einem Cu-armen RDB-Schweißgut wurde ein Late-Blooming-Effekt nachgewiesen, der sich in einem steilen Anstieg des Clustervolumenanteils und der Übergangstemperaturverschiebung nach einer Phase schwacher oder fehlender Zunahme niederschlägt. The BMWi project 1501393 aimed at contributing to the clarification of flux effects and late blooming effects in irradiated RPV steels by means of experimental techniques of sensitivity at the nm scale. The investigation of these effects was focussed on RPV steels, both base metal and weld of German reactors selected according to the objectives of the present project from two previous projects performed at AREVA GmbH. The complementary techniques of small-angle neutron scattering, atom probe tomography and positron annihilation spectroscopy were applied to detect and characterize the irradiation-induced nm-scale defect-solute clusters. A flux effect on the size of the irradiation-induced clusters but no flux effect on both cluster volume fraction and mechanical properties was found. For a low-Cu RPV weld, a late blooming effect was observed, which results in a steep slope of both cluster volume fraction and transition temperature shift after an initial stage of small or no change.

No description available.