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Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1912. / The entire thesis text is included in file. Typescript. Illustrated by authors. Deane Dwight Harris received a Bachelor of Science degree in Metallurgical Engineering and Duane Montgomery Kline received a Bachelor of Science degree in Mining, both determined from "1874-1999 MSM-UMR Alumni Directory". Title from title screen of thesis/dissertation PDF file (viewed )

Made available in DSpace on 2015-03-03T11:52:50Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-09-26Bitstream added on 2015-03-03T12:06:57Z : No. of bitstreams: 1 000799989_20150926.pdf: 1080482 bytes, checksum: 590fd3b3a1dc3fbf0c45022ade07c057 (MD5) Bitstreams deleted on 2015-09-28T16:42:58Z: 000799989_20150926.pdf,. Added 1 bitstream(s) on 2015-09-28T16:43:45Z : No. of bitstreams: 1 000799989.pdf: 2349032 bytes, checksum: a2ca00c209b46a562553100c9ecd9eb5 (MD5) / Ao longo do tempo, o uso exagerado de corantes de cabelo, em forma geral, tem apresentado um grande crescimento, e dessa forma os compostos utilizados nessas formulações comerciais tem apresentado interesse, devido a que alguns deles possuem propriedades mutagênicas e carcinogênicas. Entre os corantes que se estudam encontra-se à 2-nitro-p-fenilenodiamina e a 4-nitro-o-fenilenodiamina, que são os utilizados nas formulações comerciais de corantes semipermanentes. O presente trabalho explora metodologias para a construção de sensores que apresentem sensibilidade e seletividade suficientes para a detecção de analitos utilizados na indústria cosmética de tintura para cabelo. O sensor para o corante 2-nitro-p-fenilenodiamina, que apresentou resultados mais promissores, foi construído usando uma superfície de ouro nano-estruturado, modificado com monocamadas de mercaptopropanossulfonato de sódio (MPS), para obter uma superfície com carga negativa, seguido das etapas de formação das multicamadas de quitosana, dodecil sulfonato de sódio (SDS) e ftalocianina de níquel (TsNiPc) obtidos pela técnica layer-by-layer (LBL) em forma alternada. A partir da otimização dos parâmetros, como pH (3,5), número de multicamadas (n = 10) e eletrólito suporte (tampão Britton-Robinson 0,1 mol L-1) foram escolhidas condições para obter o melhor desempenho do sensor. A resposta do sensor foi avaliada em batelada por voltametria de onda quadrada, e em fluxo por amperometria, obtendo limites de detecção de 1,2 ?mol L-1 e 1,3 ?mol L-1, respectivamente. Na aplicação do sensor, o valor de recuperação do corante em água de torneira propositalmente contaminada foi de 97%, e o valor encontrado em uma amostra comercial mostrou um erro de 4,5% em relação ao valor de referência. / Due to the indiscriminate use of hair dyes generally has shown a tremendous growth for a long time. The compounds used in their formulations have shown commercial interest, because some of these hair dyes have mutagenic and carcinogenic properties. Among these dyes that we studied are the 2-nitro-p-phenylenediamine and 4-nitro-o-phenylenediamine, which are used in commercial formulations as semi-permanent hair dye. The present work explores methods to build sensors that have sufficient sensitivity and selectivity for the detection of analytes used in the cosmetic industry for hair dyes. The sensor for the 2-nitro-p-phenylenediamine, shows more promising results, which was constructed using a nanostructured gold surface modified with monolayers of sodium mercaptopropanossulfonato (MPS) to obtain a surface with a negative charge, followed by the steps for the formation of multilayer with chitosan, sodium dodecyl sulphonate (SDS), and nickel phthalocyanine (TsNiPc) obtained by the technical layer-by-layer (LBL) in alternating fashion. Some parameters such as pH (3.5), number of multilayers (n = 10) and supporting electrolyte (Britton-Robinson buffer 0.1 mol L-1), were optimized to obtain the best performance of the sensor. The sensor response was evaluated in batch by Square Wave Voltammetry and flow injection analysis, obtaining a detection limit of 1.2 ?mol L-1 and 1.3 ?mol L -1 respectively. For the application of sensors, the recovery of the analyte in a sample of tap water contaminated on the purpose was 97%, and the value found in a commercial sample showed an error of 4.5% in relation to the reference value.

Gold was considered for a long time to be an inert metal and was only in 1986 that the first homogeneous gold-catalyzed transformation was reported. In our laboratory, we isolated a surprisingly stable vinyl complex that resulted from an unexpected 1,2-silyl migration while working on a gold(I)-catalyzed reaction for the synthesis of polyprenylated polycyclic acylphloroglucinols (PPAPs). We herein report the isolation of a variety of organogold species where we could control the silyl migration based on the nature of the silyl group installed on the terminal alkyne. Silyl groups bearing an aromatic ring inhibited the silyl migration while the aliphatic silyl group afforded the 1,2-silyl migrated adduct. After mechanistic investigation of this intriguing migration, we believe that this process goes through a relatively rare gold vinylidene intermediate. More than 15 organogold complexes were isolated in good yield and characterized by x-ray crystallography. Investigation of their reactivity led to the formation of C(sp3)-C(sp2) bonds using electrophilic reagents without the use of Pd-based catalysts. We have also developed a new gold(I)-catalyzed dehydro Diels-Alder reaction using a simple monocyclic silyl enol ether. This methodology proceeds effectively with a wide scope by the use of [JackiephosAu(NCMe)]SbF6 in toluene. This methodology was then applied to the synthesis of magellanine, an architecturally complexed angular natural product isolated in 1976 from the club moss Lycopodium Magellanicum. The key step precursor was rapidly constructed via a Mitsunobu/Diels-Alder reaction that generated the requisite carboxaldehyde. The dehydro Diels-Alder reaction afforded the molecular skeleton of magellanine diastereoselectively in 91% yield. The synthesis was successfully accomplished in 11 steps demonstrating the ability of the gold(I) salt to rapidly construct complex molecules. Since the discovery of salvinorin A, a lot of efforts were exerted in order to optimize the biological activity for treatment of central nervous system disorders. Development of a new synthetic routes to salvinorins are essential to afford novel functionalized analogues. The decalin framework of salvinorin A was assembled with a Diels-Alder reaction with Et2AlCl followed by a gold(I)-catalyzed 6-endo-dig carbocyclization with [JohnphosAu(NCMe)]SbF6. Further functionalization afforded an elaborated intermediate which possesses the correct stereochemistry of the natural product. Following these promising results, efforts are currently in progress for the completion of the total synthesis.

The Summitville high-sulfidation gold deposit is hosted by a volcanic dome consisting of the South Mountain Quartz Latite that was erupted 23 Ma ago during formation of the Platoro Caldera complex in the San Juan volcanic field of south central Colorado. Alteration and mineralization developed during or shortly after dome emplacement as a result of metal-rich magmatic fluids and vapor emanating from a crystallizing intrusion at depth. Copper, arsenic, silver and gold are enriched in the deposit with two of the last paragenetic stages, the barite-base metal sulfide and goethite stages, containing the highest gold grades. Barite contains magmatic sulfur with a range of δ34S values (19.3 – 31.8 ‰) that reflects SO42– – H2S isotopic equilibration over a temperature range of 115 to 180 °C, which is consistent a calculated temperature of 147 °C based on the sulfur isotopic fractionation between intergrown barite and galena. Barite δ18O values (19.3 – 31.8 ‰) indicate the barite fluids contained a minor component of meteoric water. Barite growth zones with acicular crystals (wires) of emplectite (CuBiS2), a mineral not previously reported from Summitville, contained primary fluid inclusions that yielded a wide range of vapor to liquid homogenization temperatures as a result of stretching but consistent freezing point depressions that infer an average salinity of 5.1 wt. % NaCl equivalent. These data indicate that the barite fluids were modestly enriched in magmatic sulfur and metals (Cu, As, Bi, Pb, Zn, Au, Ag) and that barite precipitation was likely triggered by cooling during mixing with meteoric waters. The goethite stage developed during weathering of the deposit that likely occurred during uplift and exposure around 9 to 7.7 Ma ago based on 40Ar/39Ar dates on jarosite. The assemblage goethite + hematite ± jarosite ± scorodite ± gold filled open spaces and coated barite of the barite-base metal sulfide stage. Inclusions of barite and bladed alunite in the iron oxide/hydroxide (FeOx) matrix have the texture, composition and isotopic values of their earlier formed counterparts in the deposit and therefore represent residual material that survived the weathering event. Three 40Ar/39Ar dates on the bladed alunite ranged from 23.15 to 22.88 Ma, confirming their origin as magmatic hydrothermal alteration alunite. Layers of compositionally zoned, small rhombohedral crystals of alunite were also discovered in the FeOx matrix. Although these could not be successfully dated, they had a distinct texture, chemistry and isotopic composition (δ34S = 0.8 ‰ δ18O = 4.7 ‰) that indicated they formed during the weathering event. The acidic, oxidizing supergene fluids remobilized and broadly enriched the top of the deposit in Cu and Ag and locally in native gold (5 wt. % Ag).

Orientador: Maria del Pilar Taboada Sotomayor / Banca: Hebe de las Mercedes Villullas / Banca: Regina Massako Takeuchi / Resumo: Ao longo do tempo, o uso exagerado de corantes de cabelo, em forma geral, tem apresentado um grande crescimento, e dessa forma os compostos utilizados nessas formulações comerciais tem apresentado interesse, devido a que alguns deles possuem propriedades mutagênicas e carcinogênicas. Entre os corantes que se estudam encontra-se à 2-nitro-p-fenilenodiamina e a 4-nitro-o-fenilenodiamina, que são os utilizados nas formulações comerciais de corantes semipermanentes. O presente trabalho explora metodologias para a construção de sensores que apresentem sensibilidade e seletividade suficientes para a detecção de analitos utilizados na indústria cosmética de tintura para cabelo. O sensor para o corante 2-nitro-p-fenilenodiamina, que apresentou resultados mais promissores, foi construído usando uma superfície de ouro nano-estruturado, modificado com monocamadas de mercaptopropanossulfonato de sódio (MPS), para obter uma superfície com carga negativa, seguido das etapas de formação das multicamadas de quitosana, dodecil sulfonato de sódio (SDS) e ftalocianina de níquel (TsNiPc) obtidos pela técnica layer-by-layer (LBL) em forma alternada. A partir da otimização dos parâmetros, como pH (3,5), número de multicamadas (n = 10) e eletrólito suporte (tampão Britton-Robinson 0,1 mol L-1) foram escolhidas condições para obter o melhor desempenho do sensor. A resposta do sensor foi avaliada em batelada por voltametria de onda quadrada, e em fluxo por amperometria, obtendo limites de detecção de 1,2 μmol L-1 e 1,3 μmol L-1, respectivamente. Na aplicação do sensor, o valor de recuperação do corante em água de torneira propositalmente contaminada foi de 97%, e o valor encontrado em uma amostra comercial mostrou um erro de 4,5% em relação ao valor de referência. / Abstract: Due to the indiscriminate use of hair dyes generally has shown a tremendous growth for a long time. The compounds used in their formulations have shown commercial interest, because some of these hair dyes have mutagenic and carcinogenic properties. Among these dyes that we studied are the 2-nitro-p-phenylenediamine and 4-nitro-o-phenylenediamine, which are used in commercial formulations as semi-permanent hair dye. The present work explores methods to build sensors that have sufficient sensitivity and selectivity for the detection of analytes used in the cosmetic industry for hair dyes. The sensor for the 2-nitro-p-phenylenediamine, shows more promising results, which was constructed using a nanostructured gold surface modified with monolayers of sodium mercaptopropanossulfonato (MPS) to obtain a surface with a negative charge, followed by the steps for the formation of multilayer with chitosan, sodium dodecyl sulphonate (SDS), and nickel phthalocyanine (TsNiPc) obtained by the technical layer-by-layer (LBL) in alternating fashion. Some parameters such as pH (3.5), number of multilayers (n = 10) and supporting electrolyte (Britton-Robinson buffer 0.1 mol L-1), were optimized to obtain the best performance of the sensor. The sensor response was evaluated in batch by Square Wave Voltammetry and flow injection analysis, obtaining a detection limit of 1.2 μmol L-1 and 1.3 μmol L -1 respectively. For the application of sensors, the recovery of the analyte in a sample of tap water contaminated on the purpose was 97%, and the value found in a commercial sample showed an error of 4.5% in relation to the reference value. / Mestre

The gold mining fIrm in South Africa is viewed as a normal fIrm producing gold bearing ore but faced with a quality constraint (grade). Grade, however, is never uniformly distributed in a metalliferous deposit and because high grades are mined fIrst, the quality constraint becomes increasingly severe with cumulated production. The fIrm will continue to mine gold bearing ore until it reaches its mining limit where the marginal cost of recovering the gold is equal to the marginal revenue received from that gold and at that point the economic deposit becomes exhausted. Because the mining limit is determined by cost/technology and price, it is not fIxed and thus the point of economic exhaustion may change. When high grades are mined fIrst the relationship between the tonnage of gold ore and the grade describes the rate at which the grade is expected to fall with cumulated production. In this thesis, the grade for South African Witwatersrand gold producers is modelled to fall exponentially. The mining limit, determined by costs/technology and price, can be expressed in terms of grade. By predicting the decay in grade relative to the tonnage of gold ore and applying a mining limit, a life-time size of the economic deposit can be estimated. The remaining life of a producing gold mine can then be determined and the flow of gold predicted. An empirical treatment using the disk model of a gold deposit is undertaken for a gold mine, a goldfIeld and the total Witwatersrand gold deposit. A dynamic econometric analysis of expected mining costs and gold prices is not attempted; however certain examples are used to illustrate the applicability of the model and the influence of the South African gold mining tax formula on the life of the mine.

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Thesis (MTech (Chemical Engineering))--Cape Technikon, Cape Town, 1999 / Carbon-in-pulp (CIP) and carbon-in-leach (CIL) remain the most effective, and widely used processes for gold recovery from cyanided pulps. The extensive use of carbon in such processes have prompted many researchers to investigate the mechanism of metal cyanide adsorption. Not only has this provided many viable theories in the understanding of the mechanism, but it has also led to an improved understanding of the effects of the various operating conditions on the CIP circuit. However, the declining gold price has made gold producers aware of the need to either further optimise existing circuits or find alternative means of operation so as to improve efficiency. It is therefore the aim of this study to investigate the factors which influence the metal extraction circuit. In this study the effects of parameters such as gold and carbon concentrations, slurry density and stirring speed on the adsorption process were investigated. It was found that the effects of gold and carbon concentrations could be determined directly, that is, a definite linear relationship exists between these two parameters and adsorption rate. However, slurry density and stirring speed (power input) have a twofold effect on the process. For this reason two distinct terms called the "blinding" and "mixing" numbers have been identified. It has been shown that all the parameters investigated influences the rate of adsorption during the constant rate adsorption period. However, only solution concentration, carbon concentration and carbon loading influence the process during the diminishing rate of adsorption. This confirmed the belief that intraparticle diffusion is the rate controlling factor during the diminishing rate period. Furthermore, the point at which constant rate adsorption is replaced by the diminishing rate of adsorption is mainly a function of solution concentration.

Thesis (MTech (Chemical Engineering))--Cape Technikon, Cape Town, 2000 / In a typical gold-recovery plant, it is estimated that a substantial amount of the gold in residues may be in the form that is recoverable by cyanidation. The gold in residues can be ascribed broadly to (l) the presence of cyanicides, which consume the cyanide radical and thus inhibit dissolution of gold, (2) refractory gold resulting from coatings on some gold particles, (3) large gold particles incompletely dissolved due to inadequate contact time, (4) unliberated gold as a result of too coarse a milled product, and (5) gold dissolved during leaching, then adsorbed by other minerals or by carbonaceous matter in the pulp. This study focuses on the latter, where dissolved gold is pregrobbed during leaching by adsorbent materials in the ore. The term pregrobbing refers to the active adsorption ofgold from cyanide pregnant solutions by components ofthe ore. It has been suggested that gold already dissolved by cyanide may be adsorbed by other minerals and by carbonaceous matter in the pulp. The presence ofcarbonaceous matter in gold ores presents a two-fold problem namely, the poor release of gold from the carbonaceous matrix and the uptake of dissolved gold by the carbonaceous leach residues. Studies by several other investigators using ores from various parts of the world have similarly shown that the natural carbonaceous matter associated with refractory gold ores often behaves like activated carbon when in contact with aurocyanide solutions. Some debate also exists over the extent to which gold may be adsorbed onto the surfaces of minerals. Different authors have identified that minerals such as' pyrite, copper sulphides, quartz and layered silicates, such as kaolin, phlogopite and ilIite exhibit gold adsorbing properties. Activated carbon was first used as a model pregrobber in batch kinetic adsorption experiments in the presence of a gold selective strong base anion-exchange resin.