M. Tech. (Department of Metallurgical Engineering, Faculty of Engineering and Technology), Vaal University of Technology. / Dust generated during comminution of end of life printed circuit boards (PCB), typically having d80 of 212 μm, contains copper and gold up to 6.32 % and 635 g/ton, respectively. The dust particles being highly diverse in material makeup, an hydrometallurgical processing scheme able to selectively recover target values was studied. Use of mineral acids will result in multiple metal dissolution which will complicate subsequent solution treatments. Detailed characterization of the dust was first carried out, and leaching scheme were thereafter investigated to selectively recover gold and copper from the dust, in three leaching stages. Different conditions of ammonia and thiourea leaching were investigated to optimize agitation speed, reagents concentration, temperature and leaching time. The leaching kinetics of these elements from the dust under different prevailing leaching conditions were studied. Elemental composition of the dust size fractions indicates metal contents generally increase with decreasing dust particle size, down to – 53 μm size, which contains up to 635 g/ton Au, 25.43 % Fe, and 1.40 % Cu, compared to 51 g/ton Au, 3.07 % Fe and 6.32 % Cu in the 150–212 μm fraction. Thermodynamically, under oxidative ammonia leaching, zinc and copper ammine complex is feasible, yet zinc recovery is low. For 75 – 106 μm dust size, 2 M NH4OH, 17.5 M H2O2, 1 atm. pressure and 400 rpm in Parr reactor, Cu and Zn recoveries were 92 % and 50 %, while the activation energies evaluated within 283 – 313 K gave 47.39 kJ/mol and 33.12 kJ/mol. The kinetic analysis for copper leaching gave best correlation coefficient (R2) of 0.9804 when fitted into the chemical control model, and the rate constant was 4.4 x 10-3 at 313 K. The presence of base metals frustrates direct gold recovery from the dust using thiourea with sulphuric acid and hydrogen peroxide. Therefore, the residue obtained from the first stage copper leach was acid washed to remove iron and other residual base metal contents with 5 M H2SO4, at 333 K, 400 rpm for 2 hours. Recovery analysis shows that about 75-98 % Fe, 54-65 % Zn and 96-98 % Ni were recovered under this condition while Cu was less than 7 % at all PSDs; copper having been selectively removed at the first stage. Using 75 – 106 μm dust fraction, gold recovery was optimum when the acid wash residue was leached with 0.5 M thiourea (SC(NH2)2), 0.5 M sulphuric acid (H2SO4), 0.1 M hydrogen peroxide (H2O2) under 1 atm. pressure, 298 K and 400 rpm for 4 hours. The recovery was 98 % Au. Using this optimum for other size fractions, over 98 % gold was recovered from 150–212 μm, 106 – 150 μm and 75 – 106 μm dust while 71 % and 68 % Au were recovered from 53 – 75 μm and – 53 μm respectively. The lower recovery at the finest sizes can be due to the quantity of the gold contents deported in this particle size, which will require higher reagent dosage. The kinetic analysis gave best correlation coefficient (R2) of 0.99 when fitted to the chemical control leaching model. From this data, a process flowsheet was proposed to give separate streams rich in copper and gold values from the processed dust, with detailed processing parameters. This is considered a readily scalable process solution for retrieving gold and copper from PCB dust.

The Financial Services Modernization Act, also known as the Gramm-Leach-Bliley Act (GLBA), of 1999 has permitted U.S. bank holding companies (BHCs) to operate in non-banking activities that are financial in nature. This dissertation addresses the impact of this across-activity diversification within the U.S. financial services industry on the profitability and the risk-adjusted performance of bank holding companies. Using a variety of diversification measures, the study analyzes the relationship between corporate diversification and the financial performance of BHCs pre- and post-GLBA, from 1990 to 2011. The analysis of the profitability-diversification relationship provides evidence that the negative impact of revenue diversification on the profitability of banking firms that exists in the literature is mainly due to measurement and model specification issues. Failure to differentiate between interest-versus-noninterest and banking-versus-nonbanking types of revenue diversification has resulted in using measures of the first type of diversification to study the second, leading to inaccurate results. Moreover, introducing nonlinearity to the relationship between revenue diversification and profitability provides evidence that this relationship is negative only at relatively low levels of diversification but positive if the level of diversification is sufficiently high. Controlling for these measurement and model specification issues results in profitability premium, rather than discount, that is associated with higher levels of revenue diversification. The study also employs an event study methodology to measure how stock markets respond to mergers and acquisitions (M&As) in which BHCs acquire other banking and nonbanking financial targets. The cumulative abnormal returns (CARs) to acquirers and targets show that M&A that are either non-diversifying or diversifying within closely-related credit intermediation activities increase the value of merged firms. The effect of M&As that combine less-related financial activities on firm value is either negative or insignificant. This implies that market participants have better expectations of the future performance of less diversified firms in managing the risk-return trade-off. Comparing the average CARs of the pre- and post-GLBA eras supports this conclusion.

[pt] Esta dissertação apresenta uma análise numérica do fluxo não saturado em uma pilha de lixiviação de minério de cobre. Adicionalmente, foi feito também um estudo da estabilidade estática e sísmica da pilha de lixiviação, por sua construção estar planejada em região de alta sismicidade no sul do Peru. A pilha será construída com minério de cobre não tratado sobre base impermeável para evitar a contaminação do meio ambiente por fluxo da solução ácida através da fundação. Os resultados obtidos nas análises numéricas indicam que a pilha de lixiviação apresenta fatores de segurança satisfatórios considerando sismos de magnitude até 7,5 com aceleração máxima de até 0,30g. Da mesma forma, constatou-se que a posição da linha freática formada pela solução de lixiviação não atinge as camadas previstas para proteção das tubulações de drenagem. / [en] This dissertation presents a numerical analysis for the non saturated flow throughout a copper ore heap leach. Additionally, static and dynamic stability analyses were also made because the heap leach is planned to be built in a highly seismic region in the south of Peru. The heap will be constructed with non-treated copper ore (run of mine) on impermeable pad specially devised to avoid any possibility of ground contamination by the flow through the foundation of the acid solution used for the lixiviation process. The numerical results obtained in the stability analyses indicate that the heap leach presents satisfactory safety factors even when considering earthquakes of magnitude 7.5 with maximum acceleration of 0.30g. It has been also observed that the phreatic line formed by the lixiviation fluid does not reach the layers devised to protect the drainage pipes of the lixiviation system.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-05-03T22:56:48Z No. of bitstreams: 1 FelipeDenisMendoncaDeOliveira_TESE.pdf: 5762435 bytes, checksum: f710387481b7dc41c1ff916b28138dbf (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-05-05T19:51:58Z (GMT) No. of bitstreams: 1 FelipeDenisMendoncaDeOliveira_TESE.pdf: 5762435 bytes, checksum: f710387481b7dc41c1ff916b28138dbf (MD5) / Made available in DSpace on 2016-05-05T19:51:58Z (GMT). No. of bitstreams: 1 FelipeDenisMendoncaDeOliveira_TESE.pdf: 5762435 bytes, checksum: f710387481b7dc41c1ff916b28138dbf (MD5) Previous issue date: 2015-08-03 / Uma Rede de Sensores sem Fio (RSSF) consiste de dispositivos distribu?dos em uma ?rea com a finalidade de monitorar vari?veis f?sicas, tais como temperatura, press?o, vibra??o, movimento e condi??es ambientais em locais onde as redes cabeadas seriam complicadas ou impratic?veis de serem implementadas, por exemplo, aplica??es industriais de dif?cil acesso, monitoramento e controle de po?os petrol?feros terrestres ou mar?timos, no acompanhamento de extensas ?reas de cultivo agr?rio e animal, entre outros. Para ser vi?vel, uma RSSF deve possuir requisitos importantes, tais como baixo custo, baixa lat?ncia e, principalmente, baixo consumo de energia. Entretanto, para garantir tais requisitos, essas redes sofrem limita??o de recursos, al?m de, eventualmente, serem utilizadas em ambientes hostis, levando a altas taxas de falhas, tais como roteamentos segmentados, perda de mensagens, reduzindo a efici?ncia podendo chegar, inclusive, a comprometer a rede como um todo. Este trabalho tem por objetivo apresentar o FTE-LEACH, um protocolo de roteamento energeticamente eficiente e tolerante a falhas, mantendo a efici?ncia na comunica??o e na dissemina??o de dados. Tal protocolo foi desenvolvido baseado no padr?o IEEE 802.15.4 e voltado ?s redes industriais com recursos energ?ticos limitados. / A Wireless Sensor Network (WSN) consists of distributed devices in an area in order to monitor physical variables such as temperature, pressure, vibration, motion and environmental conditions in places where wired networks would be difficult or impractical to implement, for example, industrial applications of difficult access, monitoring and control of oil wells on-shore or off-shore, monitoring of large areas of agricultural and animal farming, among others. To be viable, a WSN should have important requirements such as low cost, low latency, and especially low power consumption. However, to ensure these requirements, these networks suffer from limited resources, and eventually being used in hostile environments, leading to high failure rates, such as segmented routing, mes sage loss, reducing efficiency, and compromising the entire network, inclusive. This work aims to present the FTE-LEACH, a fault tolerant and energy efficient routing protocol that maintains efficiency in communication and dissemination of data.This protocol was developed based on the IEEE 802.15.4 standard and suitable for industrial networks with limited energy resources

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第18806号 / 理博第4064号 / 新制||理||1585(附属図書館) / 31757 / 京都大学大学院理学研究科地球惑星科学専攻 / (主査)教授 平島 崇男, 教授 大沢 信二, 准教授 河上 哲生 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

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This project aimed to examine the separation of cobalt and nickel using solvent extraction (SX) with the extractant CYANEX 272 (C272). It was intended to investigate the Co-Ni separation in a sulphate-based leach solution in presence of other contaminants. This is an area of interest because of the difficulty of separating metals of similar properties within the field of hydrometallurgy.  Batch tests, with varying modifiers and diluents, were carried out to examine the effect of organic phase composition on phase separation. The effect of pH on equilibrium was investigated by constructing equilibrium curves. Through various shaking tests, different separation parameters were studied. McCabe-Thiele diagrams were constructed to predict design parameters. In order to simulate a continuous 3-stage countercurrent solvent extraction, batch tests were performed. Scrubbing, as means of impurity removal was also investigated. Finally, the product’s purity was examined by the help of crystallization.  The organic feed mixture that resulted in a sufficient phase separation consisted of C272, tributyl phosphate and naphtha. At pH 4, equilibrium curves showed that equilibrium was either not reached or affected by competing metal ions. A standard equilibrium curve appearance was seen at pH 4.5, resulting in that the theoretical required stages for extraction was calculated to 3 stages (A/O=1). However, a McCabe-Thiele diagram did not give an accurate representation of the more complex case (presence of contaminants). Batch simulation results gave a cobalt recovery of 69% and 100% at pH 4.5 and 4.8, and a nickel recovery of 0% and 3%, respectively. A recommended pH-value for solvent extraction could not be stated, because the choice must be based on operation specifications. Therefore, several different aspects (Co recovery, purity, and economical etc.), must be accounted for. A similar pH-trend was shown in scrubbing, where an increase of pH resulted in an increase of metal ions’ organic concentration. For stripping, acid test results proved 24 g/L sulphuric acid to give the highest cobalt concentration, with a marginal difference in concentration of impurities. An overview of the entire SX process, indicated that extraction, scrubbing, and stripping were all successful operations. The extraction stage showed a Co and Ni recovery of 99% and 0.02%, respectively, and a separation factor of 14250. Distribution results indicated that Al was difficult to remove and was transferred with Co into the product. Therefore, this element must be removed before SX. From noticing an increase of Co:Ni ratio throughout the process, solvent extraction was considered an effective separation method for cobalt and nickel separation. A considerably high purity of cobalt sulphate was produced. However, impurities Al and Ca were also detected in the product. Increasing the acetone volume in crystallization resulted in an increase of Co purity. An increase of the cobalt sulphate crystals formed was observed when increasing the acetone volume, where no impurities were detected.

[pt] O fenômeno de liquefação continua sendo um dos temas mais importantes, complexos e controversos da engenharia geotécnica, sendo a liquefação dinâmica, causada por terremotos, o maior contribuinte de risco sísmico urbano em vários países andinos. O movimento causa incrementos da poropressão que reduz a tensão efetiva e conseqüentemente a resistência ao cisalhamento de solos arenosos. O presente trabalho de pesquisa apresenta e compara algumas das metodologias existentes para a avaliação do fenômeno de liquefação dinâmica, variando desde o método semi-empírico de Seed-Idriss para estimativas do potencial de liquefação até a execução de algumas análises numéricas, no contexto dinâmico, através do programa computacional FLAC 2D v.5. Um estudo de caso, para uma comparação dos diversos procedimentos, consiste na análise dinâmica de uma pilha de lixiviação de minério de cobre, situada em região de atividade sísmica no Peru que, devido a problemas no sistema de drenagem interna, resultou com um alto nível de saturação que poderia colocar sua estabilidade em risco devido à possibilidade de liquefação sob carregamento sísmico. Dos resultados obtidos nessas análises, pode-se afirmar que o método semi-empírico de Seed-Idriss, para determinação do potencial de liquefação, compara-se bastante bem com modelos mais sofisticados baseados em análises dinâmicas empregando tanto o modelo constitutivo de Finn quanto o modelo constitutivo elastoplástico UBCSAND. / [en] The phenomenon of liquefaction is still one of the most important, complex and controversial subjects of the geotechnical engineering, being the dynamic liquefaction, caused by earthquakes, the major contributor to urban seismic risks in several Andesian countries. The shaking increases the pore water pressure which reduces the soil effective stress and, therefore, the shear strength of sandy soils. This dissertation presents and compares some of the proposed methodologies to evaluate the phenomenon of dynamic liquefaction, ranging from the semi-empirical method of Seed-Idriss to estimate the liquefaction potential to the execution of some numerical analyses, within the dynamic context, through the computational program FLAC 2D v.5. The case study, for the comparison among the several procedures, consists of a copper ore heap leach, situated in a high seismic activity zone in Peru, that experimented high levels of saturation, due to problems in the internal drainage system, that could put in risk the stability of the leach pad to the possibility of liquefaction under seismic loading. From the results of such analyses, one can say that the semi-empirical method proposed by Seed- Idriss for the determination of the liquefaction potential compares quite well with outputs from more sophisticated numerical analyses based on dynamic studies that incorporate either the Finn s or the elasto-plastic UBCSAND constitutive models.

The Wireless Sensor Networks (WSN) are self-organized systems made by nodes that communicate each other changing information and giving support in many fields. But, these networks have some limitations because the lack of resources, especially power supply. This limitation it is because, in general, the sensors have limited power supply on their battery and there is no possibility of reload this energy. But to garantee its purpose the WSN should have effective communication. The choice of a wrong routing protocol on a WSN can lead to a bad use of network resources, which leads to a less time of live and/or reducing the quality of data transmitted. Among the existing routing protocols in the literature, highlight the Leach. In this work, we performed the modeling and analysis of Leach routing protocol using Petri Nets. Simulations were performed with the NS for its validation. To analyze the performance metrics are studied as: energy savings of each node, lifetime and throughput. From the analysis of the results was possible to propose improvements to the protocol, resulting in the implementation of a new routing protocol for WSN, Leach Lua. The results showed that the Leach Lua is able to provide improvements in the metrics studied when applied in scenarios that include the use of WSNs for monitoring of fires, oil fields and vital signs of medical patients. / As Redes de Sensores Sem Fio (RSSF) são sistemas auto-organizáveis formadas por nós sensores que comunicam-se entre si trocando informações e auxiliando as mais diversas áreas. Porém, essas redes possuem grandes limitações devido à escassez de recursos, principalmente energético. Essa limitação se deve ao fato de que, em geral, os sensores possuem baterias limitadas e não há possibilidade de recarga de energia. Porém, para garantia de sua empregabilidade as RSSF devem possuir uma comunicação não somente e?caz, mas também e?ciente. Para alcançar uma comunicação e?ciente é necessário o uso de protocolos que priorizem as limitações enfrentadas por uma RSSF. A escolha equivocada de protocolos de roteamento em RSSF pode levar a uma utilização inadequada dos recursos da rede, acarretando a diminuição do seu tempo de vida e/ou diminuindo a qualidade dos dados capturados. Para o presente trabalho foi selecionado o protocolo de roteamento Leach (Low Energy Adaptive Clustering Hierarchy), para realizar através das Redes de Petri uma análise de desempenho dos componentes e fases existentes nele e posterior aplicação de melhorias. Para realizar a análise de desempenho, são estudadas métricas como: economia de energia de cada nó, tempo de vida da rede, atraso médio na entrega de pacotes, e escalabilidade. A partir do exame dessas métricas em cada uma das fases presentes no protocolo Leach, são propostas melhorias no protocolo e analisada sua empregabilidade.

This project reviews Arrowhead Credit Union's Information Security Program structure and contents.