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Richter, Willian 1985. "Purificação de biodiesel B5 com bauxita termoativada." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/256082.
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Orientador: Daniel Barrera-ArellanoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: A crescente preocupação com o meio ambiente ao longo dos anos é notória. Aspectos relevantes são a destinação de subprodutos e a emissão de gases e partículas para a atmosfera. Com a aprovação da lei n°. 11.097 de janeiro de 2005, o Brasil passou a inserção de biodiesel como substituto de diesel derivado de petróleo, que é menos poluente que os combustíveis fósseis. Porém, o acréscimo de biodiesel acarreta alguns problemas que não ocorrem com o uso de diesel puro. Destacam-se entre esses problemas os resíduos de reação e a deposição de compostos naturais, formados ou incorporados ao longo da sua cadeia de produção e distribuição. Assim o emprego de adsorvedores alternativos, como a bauxita ativada, para a remoção destes compostos tanto em biodiesel puro (B100) ou nas blendas torna-se uma opção rápida e de fácil implementação, uma vez que a sua instalação poderá ser feita no final da cadeia, nos postos de distribuição. Deste modo, o objetivo deste trabalho foi estudar um processo alternativo de purificação de biodiesel B5 sob uma coluna de bauxita ativada em processo laboratorial e piloto. O estudo empregou técnicas analíticas descritas e aprovadas pela Agência Nacional do Petróleo, Biocombustíveis e Gás Natural. Obtiveram-se também as curvas de rupturas no tratamento laboratorial para avaliar a eficiência do processo. As respostas obtidas para a determinação de contaminantes totais durante os processos mostraram uma diminuição similar nos processos laboratoriais e piloto, onde foi observada uma redução acima de 50% na escala piloto após o vigésimo primeiro dia de tratamento. Para a determinação de água foi observado uma redução de aproximadamente 90% no teste laboratorial e uma pequena redução nos primeiros dias no tratamento piloto. Os atributos de viscosidades dinâmica, cinemática e massa específica não se alteraram para ambos os processos, permanecendo dentro do estipulado pela legislação. No processo laboratorial foi observada uma redução na acidez, enquanto que na escala piloto este atributo permaneceu inalterado. Contudo, pode-se concluir com o estudo realizado que há possibilidade de utilização da bauxita ativada como agente purificador de blenda de biodiesel B5
Abstract: The growing concern for the environment over past years is notorious. Pinpoints are the allocation of by-products and the emissions of gases and particles into the atmosphere. With the approval of the law n °.11.097 from January 2005, Brazil introduced biodiesel as a substitute for petroleum products which is less polluting than fossil fuels. However, the usage of biodiesel entails some problems that do not occur with pure diesel. Prominent among these problems are the residues of reaction and the deposition of natural compounds, formed or incorporated throughout its chain of production and distribution. Thus, the use of alternative adsorbents such as activated bauxite for removing these compounds in pure biofuels (B100) or their mixtures, biodiesel B5, becomes a quick and easy to implement solution, since its installment can be made at the end of the chain at the distribution depots. Hence, the aim of this study was to investigate an alternative method of purifying biodiesel B5 in a column of activated bauxite in laboratory and pilot process. The study employed analytical techniques described and approved by the National Agency of Petroleum, Natural Gas and Biofuels. Disruption curves in laboratory processing were obtained to assess the efficiency of the process. The data obtained for total contaminants during the process showed a similar decrease in both pilot and laboratory processes where a decrease of over 50% was observed in the pilot scale after the twenty-first day of treatment. For the determination of water, a reduction of approximately 90% in the laboratory test and a small decrease in the first days of pilot treatment, were observed. The attributes of dynamic viscosity, kinematic and density were unaltered for both processes, remaining within legislation. In the laboratory process a reduction in the acidity was observed, while in the pilot it remained unchanged. In conclusion, the study reveals that the use of activated bauxite as a purification agent for B5 biodiesel blend is an optimal possibility
Mestrado
Tecnologia de Alimentos
Mestre em Tecnologia de Alimentos
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Mengler, Faron. "Gully erosion on rehabilitated bauxite mines." University of Western Australia. School of Earth and Geographical Sciences, 2008. http://theses.library.uwa.edu.au/adt-WU2008.0176.
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[Truncated abstract] Landforms rehabilitated after bauxite mining can be vulnerable to soil loss by water erosion processes. On most rehabilitated sites, management controls such as deep ripping, contour mounding and landscaped sub-catchments limit erosion. Despite these measures, severe gully erosion that is anecdotally associated with steep slopes can damage rehabilitated areas and affect downstream drinking water resources. A review of erosion dynamics reveals that gullies develop episodically and in a non-linear manner. They often initiated as a near surface process and are influenced by natural climatic drivers. Despite this, local site characteristics including soil and landform can predispose an area to gully erosion. Moreover, erosion models, becoming more-widely utilized within the mining industry, may provide useful tools with which to measure, analyse, and manage gully erosion. One of these models, SIBERIA was tested to determine its suitability for application a tool to help manage erosion risk. We first surveyed 26 eroding and erosion-prone rehabilitated hillslopes to determine the common form and setting for gully erosion on these rehabilitated bauxite mines. A conceptual model was developed to include and explore the interplay between the common causes of the gullies surveyed. The conceptual model accounts for slope steepness but suggests that additionally, certain triggers and threshold effects operating under different site conditions are as influential (or even more influential) than slope steepness as determinants of gully erosion occurrence and severity. ... Soil properties and soil erodibility had some subtle influence on landform stability and erosion risk. The most-erodible media occurred where either: mine floor material was mixed with topsoil/ overburden; and/or the topsoil/overburden layer was thin or its coverage is patchy resulting in slaking subsoil, hardsetting soil and surface crusts. When erodible surface media were combined with steeper (>8[degrees]) or longer (>50 m) slopes or with any major erosion trigger, rill and gully development was greatly intensified. The SIBERIA simulation model was calibrated and its simulated outputs were compared to known locations of gully erosion on a steep, rehabilitated pit from the Willowdale mine. At a resolution of one metre, SIBERIA was able to simulate the approximate dimensions of gullies. However, SIBERIA could not simulate the exact location of individual gully headcuts. Additionally, SIBERA was able to simulate the effect of different microtopographic surface treatments but this was only achieved by increasing the grid resolution to 25 cm and reducing the size of the area simulated due to model constraints. Locations of gully headcuts were overlain onto a grid-based, Digital Elevation Model (DEM) using a Geographic Information System (GIS). The spatial distribution of gully headcut locations was compared to DEM derivatives such as slope and flow accumulation. Positive, and predictive relationships allow between the steepness of the slope of the pre-mining landform and the cell count of the area contributing to flow (catchment), as determined by GIS, may allow a mine scale indication of erosion risk using simple GIS desktop analysis.
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Jayalatharachchi, Vishakya. "Understanding desilication products in bauxite refinery residues." Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/101127/1/Vishakya_Jayalatharachchi_Thesis.pdf.
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This research developed standard methods for quantifying and identifying alkali compounds in red mud, with a particular focus on desilication compounds. X-ray diffraction and infrared spectroscopy were used as they are relatively accessible and fast characterisation techniques for industry to use. This research is of particular importance as it will enable better predictions to be made on the suitability/stability of red mud in land rehabilitation programs.
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Desplat, Olivier. "Etude d’un procédé innovant de densification de poudres de bauxite." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEM030.
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La bauxite est un minerai utilisé pour l’élaboration de l’aluminium ou en tant que matière première pour les ciments techniques. Elle est employée, sous sa forme naturelle, en blocs. Ces blocs se font de nos jours de plus en plus rares et leur manutention peut entraîner des pertes sous formes de poussières non valorisées. L’objectif de ce projet est de recycler ces fines particules minérales sous forme de compactés afin d’améliorer l’usage des ressources naturelles minérales qui se raréfient. Ces compactés sont obtenus par compression directe puis avec un procédé innovant couplant vibration et compression. La poudre de bauxite est mélangée à du ciment et de l’eau, puis subit une phase de compaction. Ces compactés doivent avoir des propriétés spécifiques en termes de masse volumique, porosité et résistance mécanique. La micro-tomographie à rayons X est utilisée pour décrire le réarrangement granulaire et l’homogénéité 3D des porosités. La distribution poreuse est caractérisée par analyse d’image et comparée avec les résultats de porosimétrie mercure. Cette étude concernant l’évolution des paramètres texturaux des compactés amène une compréhension des phénomènes liés à la phase de compression. Le stockage et la maturation de ces compactés sous température et humidité contrôlées ont également été étudiés. L’optimisation des paramètres de compression et de formulation, comme la quantité d’eau ou de ciment dans le mélange et la pression de compression, a mené à l’amélioration des propriétés des compactés. Dans un second temps, la phase de compression et les propriétés des compactés ont été améliorées en utilisant une phase préliminaire de vibrations. Cette phase a été optimisée grâce à l’étude de plusieurs paramètres spécifiques comme le type, l’amplitude et la fréquence des vibrationsThe bauxite is used in aluminium elaboration or directly as a raw material for calcium aluminates in technical cements. It is used, as a raw material, as blocks. Recently bauxite blocks are rarer and rarer and their handling can lead to dust wastes that are not re-used. The objective of this project is to recycle the fine mineral particles in compacts to improve the use of natural mineral resources that are running out. These products are compacted by direct compaction and also with an innovative vibration and compaction process. The bauxite is mixed with cement and water, and then the mixture is compacted. They must have specific properties with higher density and mechanical resistance. X-Rays micro-tomography is used to describe the particle rearrangement and the 3D density homogeneity. The porous distribution is then characterized by image analysis and compared with the mercury intrusion porosimetry results. This study on textural parameters evolution of the compacts leads to improve an understanding about the phenomenon during the compaction stage. The storage with controlled temperature and humidity will also be studied. The optimization of the compression and mixture parameters, as amount of water or cement in the mixture and compression pressure, led us to get compacts with improved properties. In the final study, we improved the compression stage and the compacts properties by another stage using in-situ vibrations. The vibrations stage has been optimized studying several vibrational parameters especially the type, the duration, the amplitude and the frequency of the vibrations
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Poli, Delci Magalhães. "Leitos cultivados utilizando crostas de eletrofusão da bauxita." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/286836.
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Orientador: José Teixeira FilhoDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências
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Resumo: O trabalho foi desenvolvido no campo experimental da Faculdade de Engenharia Agrícola da Universidade Estadual de Campinas, Campinas, SP, posição geográfica definida pelas coordenadas 22° 53' 22" LS e 47° 044' 39" LW. O estudo procurou verificar se a utilização de crostas de eletrofusão da bauxita como substrato, em leitos cultivados construídos ou "Constructeds Wetlands" com os vegetais aquáticos emergentes Typha sp, Canna limbata e Cyperus prolifer, interfere na dinâmica do pH, fósforo e nitrogênio presentes em águas residuárias domésticas. Foram utilizados 6 tanques artificiais, sendo constituído por 3 séries de duas unidades, com fluxo vertical e saídas subsuperficiais, nominados por série Typha, leitos 3.1 e 3.2; série Canna, leitos 2.1 e 2.2; série Cyperus 1.1 e 1.2 e preenchidos com crostas de eletrofusão da Bauxita. A dimensão de cada tanque é de 4 metros de comprimento por 3 metros de largura por 1 metro de altura, totalizando 12 m³. Em cada uma das séries foram plantados os vegetais Typha sp, Canna limbata e Cyperus prolifer respectivamente. O período de monitoramento foi de setembro de 2009 a fevereiro de 2010. O desempenho do foi avaliado considerando o desenvolvimento dos vegetais, quantidades e qualidades químicas das águas residuárias. As águas foram coletadas semanalmente, em dias aleatórios, nas entradas e saídas dos tanques durante o período monitorado; os vegetais foram colhidos, somente uma vez, no final do período. As vazões médias diárias e os pH médios ocorridos no período monitorado, observados no afluente e nas saídas da série Typha foram 962 l/dia, 864 l/dia e 804 l/dia; os pH foram 6,9; 8,6 e 9,0. Na série Canna as vazões foram 954 l/dia, 797 l/dia e 735 l/dia; os pH foram 6,9; 9,2 e 9,3. Na série Cyperus as vazões foram 792 l/dia, 723 l/dia e 664 l/dia; os pH foram 6,9; 9,0 e 9,1. Os tempos de detenções hidráulicas, considerando os leitos nas séries citadas foram: 4,2 dias e 4,6 dias; 4,0 dias e 4,6 dias e 4,3 dias e 4,4 dias. As porcentagens médias de retenções de nitrogênio total nos leitos, considerando as massas que entraram, por intermédio dos afluentes, durante o período monitorado foram: a) Série Typha 27% e 19%; b) Série Canna 35% e 19%; c) Série Cyperus 32% e 21%. As remoções realizadas pelos vegetais foram: a) Série Typha 26% e 9%; b) Série Canna 42% e 11%; Série Cyperus 22% e 15%. Em relação ao fósforo, as porcentagens médias de retenções, considerando as massas que entraram nos leitos por meio dos afluentes, foram: a) Série Typha 70% e 31%; b) Série Canna 73 e 19%; Série Cyperus 74% e 27%. As remoções realizadas pelos vegetais foram: a) Série Typha 11% e 4%; b) Série Canna 17% e 4%; c) Série Cyperus 7% e 11%. As massas vegetais totais secas produzidas foram: a) Série Typha 39,9 Kg e 11.2 Kg; b) Série Canna 50,5 Kg e 26,4 Kg; Série c) Cyperus 24 Kg e 15 Kg. O estudo mostrou que o substrato promoveu alterações na eficiência e eficácia da retenção e remoção de nutriente, crescimentos dos vegetais, produção de matéria seca e qualidades da água efluente
Abstract: The study was conducted in the experimental field of the Faculty of Agricultural Engineering, State University of Campinas, Campinas, SP, geographical position defined by coordinates 22° 53' 22" LS and 47° 04' 39" LW. The study examined whether the use of bauxite electrofusion crusts, as a substrate in constructed wetlands with emergent vegetables Typha sp, Canna limbata and Cyperus prolifer, interferes on the dynamics of pH, phosphorus and nitrogen present in domestic wastewater. It was used 6 artificial beds, consisting of 3 sets of two units with vertical flow and subsurface outflows, nominated by Typha series, 3.1 and 3.2 beds; series Canna, 2.1 and 2.2 beds, series Cyperus, 1.1 and 1.2 and filled with Bauxite electrofusion crusts. The size of each bed was 4 meters long by 3 meters wide by 1 meter high, totaling 12 m³. In each series the vegetables Typha sp, Canna limbata and Cyperus prolifer were planted respectively. The monitoring period was from September 2009 to February 2010. The performance was evaluated considering the development of plants, the chemical quantities and qualities of wastewater. The waters were collected weekly, on random days, at the entrances and exits of the beds during the monitoring period; the plants were harvested only once, at the end of each period. The average daily flow rates and average pH occurred during this period, observed in the tributary and the outflow of the series Typha were 962 l/day, 864 l/day and 804 l/day, the pH were 6.9, 8.6 and 9.0. In the series Canna flow rates were 954 l/day, 797 l/day and 735 l/day, the pH were 6.9, 9.2 and 9.3. In the series Cyperus flow rates were 792 l/day, 723 l/day and 664 l/day, the pH were 6.9, 9.0 and 9.1. The hydraulic detention time, considering the beds in the series cited were 4.2 days and 4.6 days, 4.0 days and 4.6 days and 4.3 days and 4.4 days. The average percentage of total nitrogen retention in the beds, considering the masses that came through the tributaries during the monitoring period was: a) Series Typha 27% e19% b) Series Canna 35% and 19%, c) Series Cyperus 32% and 21%. The removals conducted by the plants were : a) Series Typha 26% and 9%, b) Series Canna 42% and 11%; Series Cyperus 22% and 15%. Regarding the phosphorus, the average percentage of retention, considering the masses that entered the bed through the tributaries was: a) Series Typha 70% and 31%, b) Canna Series 73 and 19%; Series Cyperus 74% and 27 %. The removals conducted by the plant were: a) Series Typha 11% and 4%, b) Series Canna 17% and 4%, c) Cyperus Series 7% and 11%. The total dry plant mass produced were: a) Series Typha 39.9 Kg is 11.2 Kg b) Series Canna 50.5 kg is 26.4 kg; Series c) Cyperus 24 Kg is 15 Kg. The study has shown that the substrate promoted changes in the efficiency and effectiveness of nutrient removal and retention, growth of vegetables, dry material production and quality of effluent water
Mestrado
Análise Ambiental e Dinâmica Territorial
Mestre em Geografia
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Costa, Jaime Henrique Barbosa da. "Modelagem matemática da operação de escrubagem da bauxita de Paragominas-PA." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/3/3134/tde-20102010-152632/.
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O objetivo deste trabalho foi investigar, sob o enfoque da modelagem matemática, a operação de escrubagem da bauxita proveniente da jazida Miltônia 3, da Mina de Bauxita de Paragominas-PA, com vistas a fornecer parâmetros para previsão de seu desempenho e otimização. Para isso, foi realizada uma campanha de experimentos de escrubagem, em um tambor desagregador de laboratório, baseada em planejamento fatorial. Os parâmetros operacionais avaliados foram os seguintes: grau de enchimento, tempo de residência da polpa e velocidade de rotação. A variável de resposta selecionada foi a quantidade de finos (partículas menores que 0,037 mm) no produto desagregado. O programa de experimentos permitiu a análise da influência de cada variável operacional selecionada na desagregação da bauxita. De acordo com os resultados obtidos, o parâmetro operacional que produziu o efeito mais significativo na variável de resposta foi o grau de enchimento. O modelo desenvolvido foi validado através da comparação entre os valores obtidos em ensaios de escrubagem em uma unidade piloto e aqueles previstos pelo modelo. Os valores da quantidade de finos, no produto desagregado, previstos pelo modelo apresentaram uma excelente aproximação com os dados experimentais da operação em escala piloto.The aim of this study was to investigate and model the bauxite scrubbing of bauxite samples from Miltonia 3, a Vale operation at Pará state, Brazil. The experimental program included the design of a standard laboratory test, from which parameters were derived for predicting the operation of a scrubber in steady state conditions. Three main variables were selected for the laboratory experimental program using the factorial design technique. These were load fraction, residence time and rotation speed. The amount of fines was determined through screening both feed and product of the scrubbing test. The former was considered as a material characteristic while the second was the dependent variable, i.e. the result of the scrubbing process. An empirical model was developed according to which the load fraction was found the most important variable to the scrubbing process. Residence time was also included in the model due to its importance in designing scrubbers for industrial plants. To validate the model a comprehensive pilot plant program was carried out with the same bauxite sample from Miltonia 3 deposit used in the laboratory investigations. The comparison between experimental data and model calculated values indicated a good agreement, as most values were within ±10% deviation range.
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Bortoleto, Daniel Armelim. "Avaliação da heterogeneidade da bauxita de Juruti (PA) visando à otimização de protocolos de amostragem." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/3/3134/tde-29122015-151004/.
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O controle de qualidade na indústria mineira visa à extração de recursos naturais com confiabilidade e efetividade a um custo mínimo. A compreensão e a aplicação da teoria da amostragem (Theory of Sampling ou TOS), desenvolvida por Pierre Gy, de forma integrada ao gerenciamento do processo, são essenciais para alcançar esse objetivo. Por este motivo, ressalta-se a importância de expor os benefícios de uma amostragem correta a todos os níveis hierárquicos de um empreendimento mineiro, a fim de se obter o engajamento da equipe técnica e operacional, assim como o orçamento necessário para financiar treinamentos e compra de equipamentos adequados para uma amostragem precisa e acurada. Uma amostra jamais apresentará características idênticas àquelas do material de origem, devido à existência do erro fundamental de amostragem, que está associado à heterogeneidade constitucional do material. Ainda existem os demais erros que surgem no decorrer das operações de amostragem, como, por exemplo, o erro de segregação e agrupamento, associado à heterogeneidade distribucional e onde a força da gravidade assume papel preponderante. Cada etapa do processo de amostragem gera um erro que deve ser conhecido para a determinação da confiabilidade das estimativas. Neste contexto, os testes de heterogeneidade são uma ferramenta imprescindível para adquirir o conhecimento sobre a variabilidade natural da jazida e para conduzir a amostragem de uma forma correta, gerando amostras representativas. O presente trabalho estuda a heterogeneidade do minério de alumínio da região oeste do Pará, a partir dos resultados obtidos em diferentes experimentos descritos na literatura com base na teoria da amostragem. Os resultados dos experimentos permitem, então, otimizar os protocolos de amostragem, assim como determinar as massas mínimas representativas para amostras de bauxita.Quality control in the mineral industry context is directed to extraction of natural resources with reliability, effectiveness and minimum cost. The understanding and application of the Theory of Sampling (TOS), developed by Pierre Gy, integrated with, process management are essential for reaching this objective. For this reason, it is important that all levels of personnel in a mining enterprise are made aware of the benefits of correct sampling so as to gain the engagement of the technical and operational team and equally, the necessary budget for training and purchase of appropriate equipment for sampling that is precise and accurate. Samples will never present exactly the same characteristics as the lot from which they originate because of the constitutional heterogeneity which generates the fundamental sampling error. Other errors arise in sampling operations; for example, the grouping and segregation errors related to distributional heterogeneity, where gravity assumes the most important role. Each stage of the sampling process produces an error which must be known for determining the reliability of the estimates. In this context, the heterogeneity tests are an essential tool for knowing the natural variability of the deposit, and to conduct sampling in a correct manner to generate representative samples. The present work studies the heterogeneity of the aluminum ore in western Pará, based on the results of different heterogeneity experiments described by the TOS. Results allow the optimization of sampling protocols as well as the determination of the minimum masses representative samples of bauxite.
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Vilela, Vívian Maria de Faria Nasser. "Anfíbios anuros em áreas em processo de restauração florestal após mineração de bauxita, Poços de Caldas-MG." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/11/11150/tde-16082012-161724/.
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Dentre as atividades envolvidas no processo de mudança do uso da terra, está a mineração de bauxita, cuja atividade leva à constante perda de hábitat. Uma forma de reparar a degradação antrópica à diversidade e ao funcionamento dos ecossistemas naturais é utilizar o processo de restauração ecológica. Este trabalho utilizou armadilhas-de-queda para estudar o efeito da restauração florestal após a mineração de bauxita na abundância de anuros de serapilheira. Os pontos amostrais encontram-se em um mosaico vegetacional no planalto de Poços de Caldas, MG, sendo dois locais em processo de reabilitação, cinco em processo de restauração e dois locais em remanescentes secundários de Floresta Estacional Semidecidual Montana. Foram coletados dados referentes a características da vegetação (área basal; densidade; abertura do dossel e espessura da serapilheira) e a altitude em cada ponto amostral. O Critério de Informação de Akaike corrigido (AICc) foi usado para avaliar a eficácia de nove modelos construídos a priori na predição da abundância das duas espécies coletadas que apresentaram suficiência amostral, separadamente. A abundância de Rhinella pombali foi inversamente relacionada com a densidade da vegetação e com a altitude. O modelo com a abertura do dossel influenciou positivamente a abundância de Ischnocnema juipoca. A restauração florestal possibilitou a recolonização por duas espécies de anuros - E. juipoca e R. pombali, evidenciando a importância dessa atividade na reconstrução de habitats para a biodiversidade nativa.Bauxite mining is one of the activities involved in land-use change that leads to total habitat loss. The process of ecological restoration is a way to repair anthropic damages to biodiversity and to natural ecosystems functioning. In this work, pitfall traps with drift fences were used to verify the influence of restoration of forest areas priorly submitted to bauxite mining on the abundance of leaf litter anurans. Sample sites were located in vegetation patches on the plateau of Poços de Caldas-MG, Brazil: two in areas under rehabilitation process, five in areas under restoration process and two in secondary fragments of Montane Semideciduous Seasonal Forest. Data concerning characteristics of vegetation (basal area, density, canopy openness and litter thickness) and height were collected in each sample site. The corrected Akaike Information Criterion (AICc) was used to evaluate the efficiency of nine models constructed a priori to predict abundance of two species collected that presented sampling sufficiency, analysed as separate groups. Abundance of Rhinella pombali was inversely related to height and vegetation density. The canopy openness model positively influenced abundance of Ischnocnema juipoca. Recolonization by two anuran species E. juipoca and R. pombali was possible due to forest restoration, which shows the importance of this process in reconstructing habitats for native biodiversity.
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Ahmad, Ishaq [Verfasser]. "Beneficiation of Bauxite by Washing Processes / Ishaq Ahmad." München : Verlag Dr. Hut, 2012. http://d-nb.info/1020298588/34.
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Petersen, Tanya M. "Characteristics of desilication products in bauxite refining residue." Thesis, Petersen, Tanya M. (1992) Characteristics of desilication products in bauxite refining residue. Masters by Research thesis, Murdoch University, 1992. https://researchrepository.murdoch.edu.au/id/eprint/52451/.
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The production of alumina from bauxite by the Bayer process generates a large volume of residue (red mud). This residue contains a percentage of complex zeolitic sodium aluminium silicates, formed by the precipitation of silica from the Bayer liquor and are known as the desilication product or DSP. The presence of DSP in red mud contributes significantly to making the residue highly alkaline and high in sodium and therefore a potential environmental hazard upon disposal.
This thesis documents the findings of a study with the objective of examining the nature and behaviour of a DSP-type mineral, determining its stability, including the way in which the release of sodium occurs and the potential for cation exchange. By so doing, a clearer picture of the DSP in red mud and its reaction to environmental factors, such as the pH of water percolating through the red mud disposal sites, was sought. An insight into the possibility of predisposal treatments, such as mixing the mud with acid waste or with material that would induce a favourable cation exchange was similarly gained.
A laboratory-synthesised DSP mineral was used in these studies, because of the difficulty of working with red mud, in which DSP is cloaked with other residue minerals. The similarity of various synthetic DSPs (including the synthetic material used for this work) to that found in red mud was examined. It was found that the DSP formed at Alcoa's Kwinana plant (Western Australia) was a composite of the minerals noselite/nosean and sodalite, with sulphate being the main anion incorporated into the DSP. The synthetic mineral used in the study was therefore a mixture of the three aforementioned minerals.
The sensitivity of synthetic and non-synthetic DSP to the citrate-bicarbonate-dithionite {CBD} method, used in leaching away the iron oxide that masks the DSP in red mud was examined. No significant effect on the DSP after leaching by CBD was observable. This confirmed that studies of DSP in red mud after removal of iron oxides by the CBD method were valid.
In the study of DSP stability, its behaviour at various levels of acidity and alkalinity was noted, to determine
under what disposal conditions the potentially harmful release of sodium is most likely to occur and to provide
information relevant to acid-waste treatment of red mud before or at disposal. Synthetic DSP samples were subjected to a range of pH conditions, from very alkaline to very acidic, over a range of time periods up to three weeks duration. The results of these tests indicated that DSP is stable to pHs as low as 8.5, with no significant release of sodium to the environment after 3 weeks.
The study of cation exchange behaviour in DSP was undertaken to determine if exchanging sodium (which is toxic to plants) for some likely cations such as potassium or ammonium (plant nutrients) may feasibly be used to rehabilitate red mud, since zeolitic minerals like those in DSPs are noted for their ion exchange properties. The exchange of sodium from within synthetic DSP for potassium, ammonium and calcium ions was investigated. It was concluded that the cubic crystal habit of the DSP examined restricted the exchange of sodium ions with cations such as calcium, but allowed other cations (particularly potassium) to penetrate and replace up to 30% of the sodium ions contained within the lattice. Therefore treatment of red mud with waste solutions high in potassium prior to disposal would be beneficial. The exchangability of sodium for ammonium was also significant (16%), meaning that treatment of red mud with waste solutions containing ammonium would also be beneficial to revegetation of the red mud lakes.
Overall the study shows that red mud could be neutralised to a pH of 8.5 and treated with a waste solution high in potassium and/or ammonium in order to make the disposal sites more amenable to rehabilitation and revegetation.
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Hanaor, Dorian Amir Henry Materials Science & Engineering Faculty of Science UNSW. "Retention of the anatase phase in TiO2 through the use of bauxite and zircon dopants." Awarded by:University of New South Wales. Materials Science & Engineering, 2008. http://handle.unsw.edu.au/1959.4/41327.
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Preserving the anatase phase of TiO2 is of interest due to the photocatalytic activity of this phase, which is generally considered superior to rutile Ti02 due to a higher surface area. The retardation of the anatase to rutile transition through the use of low cost dopants, zircon and bauxite, was investigated. Pressed powder compacts of anatase TiO2 doped with varying levels of bauxite and zircon powders were fired at 1025??C for durations of 2, 3 and 4 hours. X-ray diffraction analysis, Scanning electron microscopy, Energy dispersive X-ray spectroscopy and Raman spectroscopy were used to evaluate the effect these dopants have on the transition to rutile. It was found that both zircon and bauxite retard the transition to rutile in the solid state. Increasing the level of bauxite dopant consistently increases the preservation of the anatase phase. It was found that at levels of bauxite doping over 5 wt%, over 90% of the anatase phase is retained through 2 hour firing cycles. Using EDS, zircon particles were observed to nucleate elongated prismatic rutile grains. Whilst XRD analysis showed that the addition of zircon has a marked effect on retarding the overall transition of anatase to rutile, increasing levels of this dopant over 2.5% brings about a reduction in preserved anatase, probably due to increased rutile nucleation. Findings showed Samples doped with 2.5% ZrSi04 retained approximately 95% anatase through 2 hour firing cycles.
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Flynn, Mary Patricia. "The settling characteristics of bauxite particles after acid reaction." Thesis, Queen's University Belfast, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356914.
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Carswell, Leslie. "Fungi associated with plant deaths in rehabilitated bauxite mines." Thesis, Carswell, Leslie (1993) Fungi associated with plant deaths in rehabilitated bauxite mines. Honours thesis, Murdoch University, 1993. https://researchrepository.murdoch.edu.au/id/eprint/32821/.
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Alcoa of Australia is committed to reintroduce 80% of the jarrah forest plant. species back onto rehabilitated bauxite mines in south western Australia by 1997. It has been observed that plant deaths do occur on these mines. The aim of this project was to determine if plant pathogens were responsible for these deaths. Healthy, sick and dying plants were sampled over a 5 week period initiated in February 1993. The following isolates were obtained from 19 plant species: 25 Fusarium spp., 11 Botryosporium sp., 8 Bdtryosphaeria ribis, 5 Cytospora eucalypticola, 6 Phoma spp. isolates, 5 Gelasinospora spp., 4 Diaporthe sp., 4 Pestalotiopsis sp., 3 Phonzopsis spp., 1 Dichomera eucalypti, 1 Phytophthora sp., 1 Monochaetia sp. and 1 Botrytis cinerea isolate. Many other fungi were isolated but could not be identified. Not all isolates were tested in glasshouse or field pathogenicity trials. Two B. ribis isolates were lesion forming in glasshouse trials. Gelasinospora, C. eucalypticola, Botryosporium and D. eucalypti were not lesion forming but were reisolated from the wound tissue, indicating that these fungi had the potential to be pathogenic. Field trials initiated in June (winter) (duration of 3-6 weeks) showed 3 B. ribis, 1 C. eucalypticola, and 1 Phoma sp. isolates to be lesion forming. Many isolates were not lesion forming including B. ribis, C. eucalypticola, Diaporthe, Botryosporium, Phoma, Phomopsis, D. eucalypti, and Fusarium but were reisolated from wound tissue, indicating they have the potential to be pathogens. Environmental conditions were felt to be responsible for the lack of lesions in the plants and it was recommended that these pathogenicity tests be repeated in summer, when environmental conditions are likely to be conducive to disease.
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Jorge, Fernando Augusto Silveira. "Estudo da adsorÃÃo do gossipol existente em Ãleo de semente de algodÃo." Universidade Federal do CearÃ, 2006. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=1524.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoExistem poucas pesquisas que abordam o comportamento do gossipol presente em Ãleo de semente de algodÃo frente a materiais adsorventes. As tÃcnicas de adsorÃÃo sÃo bastante utilizadas em tecnologias de diversas naturezas e segmentos industriais, desde tratamento de resÃduos industriais tÃxicos atà em aplicaÃÃes nas indÃstrias alimentÃcia e farmacÃutica. Por outro lado, o gossipol, aldeÃdo polifenÃlico com efeitos tÃxicos em ruminantes jovens e nÃo ruminantes, presente na semente das plantas do gÃnero gossypium (algodoeiro), tem sido objeto de estudo pelas suas importantes atividades biolÃgicas. O presente trabalho tem como objetivo fundamentar cientificamente e tecnologicamente, no que concerne ao comportamento do gossipol no fenÃmeno de adsorÃÃo, um processo industrial capaz de reduzir o teor de desse pigmento presente em Ãleo de semente de algodÃo. Foram selecionados alguns tipos de adsorvente: argila ativada e a bauxita calcinada termo ativada. A isoterma de adsorÃÃo do gossipol em bauxita ativada se ajustou melhor ao modelo de Langmuir e a argila ativada ao modelo Freundlch. A bauxita ativada apresentou melhor capacidade de adsorÃÃo do gossipol do que a argila ativada. A primeira adsorveu 65,9 e 85,1, dados em _mol de gossipol por grama de adsorvente, nas temperaturas de 60ÂC e 80ÂC respectivamente, e a segunda 43,3 e 56,7 nas mesmas temperaturas. Contudo a bauxita ativada foi ineficiente na reduÃÃo da cor. Este fato se deve provavelmente a transformaÃÃes do gossipol, indicando que a concentraÃÃo dessa substÃncia nÃo possui relaÃÃo direta com a intensidade da cor. SÃo necessÃrios estudos da transformaÃÃo do gossipol relacionados aos tratamentos tecnolÃgicos sugeridos para sua eliminaÃÃo no Ãleo bruto de algodÃo. De forma geral, observamos que a retirada do gossipol atravÃs de adsorÃÃo por si sà nÃo à suficiente para empreender um projeto de refino alternativo para o Ãleo bruto de algodÃo. As tÃcnicas de adsorÃÃo provavelmente serÃo coadjuvantes em um processo de refino modificado desse produto.
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Jorge, Fernando Augusto Silveira. "Estudo da adsorção do gossipol existente em óleo de semente de algodão." reponame:Repositório Institucional da UFC, 2006. http://www.repositorio.ufc.br/handle/riufc/17441.
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JORGE, Fernando Augusto Silveira. Estudo da adsorção do gossipol existente em óleo de semente de algodão . 2006. 60 f. : Dissertação (mestrado) - Universidade Federal do Ceará, Centro de Ciências Agrária, Departamento de Tecnologia de Alimentos, Fortaleza-CE, 2006Submitted by Nádja Goes (nmoraissoares@gmail.com) on 2016-06-03T14:24:37Z No. of bitstreams: 1 2006_dis_fasjorge.pdf: 790784 bytes, checksum: 03e5e74bb469517cf658aeda665d7bad (MD5)
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Existem poucas pesquisas que abordam o comportamento do gossipol presente em óleo de semente de algodão frente a materiais adsorventes. As técnicas de adsorção são bastante utilizadas em tecnologias de diversas naturezas e segmentos industriais, desde tratamento de resíduos industriais tóxicos até em aplicações nas indústrias alimentícia e farmacêutica. Por outro lado, o gossipol, aldeído polifenólico com efeitos tóxicos em ruminantes jovens e não ruminantes, presente na semente das plantas do gênero gossypium (algodoeiro), tem sido objeto de estudo pelas suas importantes atividades biológicas. O presente trabalho tem como objetivo fundamentar cientificamente e tecnologicamente, no que concerne ao comportamento do gossipol no fenômeno de adsorção, um processo industrial capaz de reduzir o teor de desse pigmento presente em óleo de semente de algodão. Foram selecionados alguns tipos de adsorvente: argila ativada e a bauxita calcinada termo ativada. A isoterma de adsorção do gossipol em bauxita ativada se ajustou melhor ao modelo de Langmuir e a argila ativada ao modelo Freundlch. A bauxita ativada apresentou melhor capacidade de adsorção do gossipol do que a argila ativada. A primeira adsorveu 65,9 e 85,1, dados em _mol de gossipol por grama de adsorvente, nas temperaturas de 60ºC e 80ºC respectivamente, e a segunda 43,3 e 56,7 nas mesmas temperaturas. Contudo a bauxita ativada foi ineficiente na redução da cor. Este fato se deve provavelmente a transformações do gossipol, indicando que a concentração dessa substância não possui relação direta com a intensidade da cor. São necessários estudos da transformação do gossipol relacionados aos tratamentos tecnológicos sugeridos para sua eliminação no óleo bruto de algodão. De forma geral, observamos que a retirada do gossipol através de adsorção por si só não é suficiente para empreender um projeto de refino alternativo para o óleo bruto de algodão. As técnicas de adsorção provavelmente serão coadjuvantes em um processo de refino modificado desse produto.
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Dani, Norberto. "Pétrologie des altérations postmagmatiques et météoriques des roches alcalines de Lages, SC [Santa Catarina], Brésil." Poitiers, 1998. http://www.theses.fr/1998POIT2345.
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L'objectif specifique de ce travail est d'investiguer le processus d'alteration et la generation des depots de bauxite, associes aux roches alcalines affleurantes dans la region de lages, santa catarina, bresil. La revision chimique et petrographique a permis de regrouper les roches alcalines feldspathiques en phonolites de type sud et phonolites de type nord, etant remarquable dans ce dernier groupe, l'existence d'un processus differencie d'alteration endogene, de type postmagmatique. Dans ce contexte, l'intensite de l'alteration endogene a ete decisive dans la formation des depots, etant une des principales causes de la distribution concentree de la bauxite dans les phonolithes de type nord. Il a ete effectue une reevaluation des donnees disponibles sur la geomorphologie regionale et locale, aussi bien que des evenements geologiques responsables du modele actuel du terrain. Cette analyse, associee aux informations obtenues a partir de l'application de techniques de datation par traces de fissions sur apatites, ont determine l'impossibilite de generation de la bauxite a partir du tertiaire inferieur. Les produits d'alteration meteorique convergent vers une paragenese formee d'un ensemble restreint de mineraux secondaires, l'halloysite, des hydroxydes et des oxyhydroxydes d'aluminium, de fer et de titane etant remarquables. L'etude de detail prouve l'existence d'une phase de basse cristallisation, de type allophane si-al, de reactivite elevee et intermediaire entre les mineraux primaires de composition felsique du phonolithe et des phases secondaires comme l'halloysite et des mineraux d'aluminium. Pour la premiere fois au bresil est decrite l'apparition naturelle du polymorphe d'al(oh)#3 type nordstrandite, les raisons de cette speciation des composes d'aluminium a lages etant inferees au long de ce travail. De la meme maniere, la nucleation precoce de la boehmite est en desaccord avec les modeles actuellement en vigueur quant a la distribution de cette phase dans des laterites. On investigue les raisons de la nucleation de l'halloysite dans ces roches, ainsi que l'importance du milieu dans la cristallisation et la morphologie de cette phase.
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Yagmurlu, Bengi [Verfasser]. "Innovative Technologies for Scandium Recovery from Bauxite Residue / Bengi Yagmurlu." Düren : Shaker, 2021. http://d-nb.info/1236834453/34.
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Ee, Valarie. "The bioremediation of bauxite residue (red mud) using indigenous bacteria." Thesis, Ee, Valarie (1999) The bioremediation of bauxite residue (red mud) using indigenous bacteria. Honours thesis, Murdoch University, 1999. https://researchrepository.murdoch.edu.au/id/eprint/38384/.
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The objectives of this project were to contribute to the understanding of the microbiology of red mud and the possibility of neutralizing red mud using the metabolic activities of indigenous bacteria.
Red mud taken from the Pinjarra refinery of Alcoa of Australia Limited was found to be highly alkaline (pH 10.2 - 13.2) and saline (EC 9.99 dS/m) with up to 0.54 % w/w organic carbon. Despite these harsh conditions, 16 mesophilic, facultatively anaerobic bacteria were isolated from the red mud by enrichment culture. Amongst these isolates were Gram negative and positive motile rods and a Gram negative non-motile coccus, with varying tolerance to NaCl and pH. The majority of the isolates were able to produce acidic compounds in glucose media, either by oxidation, fermentation or both. These isolates were then inoculated into glucose amended sterile red mud to test the possibility of pH reduction by bacterial metabolism.
Three of the isolates were able to reduce the pH of sterile red mud amended with 6 % w/w glucose to near neutral conditions after 12 weeks. This required the production of approximately 0.2 mols W/100 g red mud under aerobic conditions. Glucose in varying amounts was also added to non-sterile red mud to encourage the growth of the bacterial community in red mud. Greatest pH reduction in non-sterile red mud occurred in the presence of 3 % w/w glucose under aerobic conditions. For both glucose amended sterile and non-sterile red mud, there was a strong positive correlation between bacterial biomass and pH reduction. In addition, pH reduction did not occur in the absence of oxygen.
The experiments showed that in the presence of glucose and under aerobic conditions, it is possible to reduce the pH of red mud using the metabolic products of indigenous bacteria.
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Ayorinde, Adebayo O. "MINERALOGY AND GEOCHEMISTRY OF THE BAUXITE DEPOSITS (CRETACEOUS), WILKINSON COUNTY, GEORGIA." Digital Archive @ GSU, 2011. http://digitalarchive.gsu.edu/geosciences_theses/30.
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Cretaceous bauxite deposits from Hall and Veneer mines, Wilkinson County, Georgia are composed of kaolinite, gibbsite, goethite, anatase, nordstrandite and bohemite. Quartz and micas are absent in the samples. The presence of boehmite and goethite are evidence of intense weathering forming the bauxite deposits. The extremely high values of the Chemical Index of Alteration (CIA) which is over 99, and the low values of the alkali metals and alkali earth metals, support an intense weathering origin for the bauxite deposit. There is evidence of deposition in the mines based on the presence of pisoids in the bauxite samples and the composition of the parent materials, which vary markedly by the non-uniform TiO2/Al2O3 values which represent the accumulation of transported materials from contrasting source areas. Kaolin minerals were first produced by the hydrolytic weathering of aluminous sediments and then gibbsite was formed as early kaolin was desilicated.
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Collins, Shane M. "Improving rehabilitation practices for the outer batter slopes of bauxite residue disposal areas at Worsley refinery, Collie, Western Australia /." Access via Murdoch University Digital Theses Project, 2002. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20040510.154254.
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Gherardi, Mark James. "Availability and management of manganese and water in bauxite residue revegetation." University of Western Australia. Soil Science and Plant Nutrition Discipline Group, 2004. http://theses.library.uwa.edu.au/adt-WU2005.0038.
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[Truncated abstract] Industrial processing to refine alumina from bauxite ore produces millions of tonnes of refining residue each year in Australia. Revegetation of bauxite residue sand (BRS) is problematic for a number of reasons. Harsh chemical conditions caused by residual NaOH from ore digestion mean plants must overcome extremely high pH (initially >12), saline and sodic conditions. At such high pH, manganese (Mn) is rapidly oxidised from Mn2+ to Mn4+. Plants can take up only Mn2+. Thus, Mn deficiency is common in plants used for direct BRS revegetation, and broadcast Mn fertilisers have low residual value. Added to this, physical conditions of low water-holding capacity and a highly compactable structure make BRS unfavourable for productive plant growth without constant and large inputs of water as well as Mn. However, environmental regulations stipulate that the residue disposal area at Pinjarra, Western Australia, be revegetated to conform with surrounding land uses. The major land use of the area is pasture for grazing stock. Hence, pasture revegetation with minimum requirement for fertiliser and water application is desirable. This thesis investigates a number of avenues with potential for maintaining a productive pasture system on BRS whilst reducing the current level of Mn fertiliser and irrigation input. Emphasis was placed on elucidation of chemical and physical factors affecting Mn availability to plants in BRS
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Farrokh, Mohammad. "Thermodynamic process modeling and simulation of a diaspore bauxite digestion process." Licentiate thesis, Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-19001.
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Bauxite ores which originated from separate mines have different characteristics, i.e. each bauxite ore has its own individual specifications. Jajarm bauxite is of the diaspore-chamosite type and its alumina to silica mass ratio is lower than other diaspore ores. Diaspore bauxite digestion in comparison with other bauxite types has more complicated operational conditions and requires higher temperature, pressure and caustic concentration. The present study was thus performed on the above mentioned digestion process and include two parts. First, the behavior of some key parameters of the process was experimentally investigated. Second, a simulation model was developed to predict the performance of the process, particularly thermal energy consumption. The model was validated with several sets of the industrial data and close agreement was found. The effects of various trends in pressure drops of the flash tanks on the slurry preheating were analyzed. The results showed that the proposed pressure profile can lead to an increase in the furnace inlet slurry temperature. Alternatively, it can lead to an appreciable decrease in the furnace fuel consumption, which is required for having the existing operating temperature. The generated vapor in different stages of the process was determined. A considerable amount of the generated water vapor and thermal energy were lost. The model was further developed to study the effect of using a part of these vapors on heat recovery. The simulation results showed that in the new design, the pre-heater sections can gain 5.71GJ/h additional heat and the fresh slurry temperature increases by 11°C. Therefore, the furnace required energy is reduced by 11.9%. The new design was implemented in the refinery and according to the energy department report, it has reduced the furnace fuel consumption by 8%, which is around 200kg of natural gas /h less than the earlier condition for every digestion line.
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Goloran, Johnvie Bayang. "Nitrogen and Phosphorus Dynamics in Highly Alkaline Bauxite-processing Residue Sand." Thesis, Griffith University, 2014. http://hdl.handle.net/10072/365715.
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The demand for lightweight metal such as aluminium (Al) has substantially increased worldwide. Alumina is extracted from bauxite ore through the Bayer process, which uses hot caustic soda, resulting in the production of highly alkaline, saline and sodic bauxite residue. Global bauxite residue production is estimated at 120 million tons per annum with the establishment of sustainable vegetation cover systems (e.g. dust emission control crops) in residue storage areas (RSAs) as the key objective in rehabilitation activities. In Western Australia, Alcoa of Australia employs the dry-stacking method for managing bauxite processing residue at RSAs. In this method, residue is separated into mud (<150 μm) and sand (>150 μm) fractions with the latter being used for constructing the RSAs’ perimeter embankments. The sand fraction, referred to in this study as bauxite-processing residue sand (BRS), exhibits a low nutritional status [i.e. nitrogen (N) and phosphorus (P) < 1 mg kg-1] and poor water holding capacity, which can severely restrict the availability of key plant nutrients.
The key objectives of this study were to a) assess analytic and diagnostic methods for determining N and P availability indices suitable for use in highly alkaline BRS for an improved and efficient fertilization strategies in the RSAs; b) determine the most suitable organic or inorganic amendment materials that would enhance the growth environment by improving N and P availability, plant N and P uptake by plants, and vegetation growth in BRS; c) assess the fate (including chemical and biological transformation) of applied 15N fertilizer, plant growth response and the role of the microbial community in the dynamics of N in BRS with and without greenwaste compost; and, d) determine which type of fertilizer is most suitable to improve the nutrient status and plant growth in BRS.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
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Agbolosoo, Emmanuel Kwami. "Mineral processing in a less developed country: Bauxite processing in Ghana." Diss., The University of Arizona, 1991. http://hdl.handle.net/10150/185546.
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The purpose of this dissertation is to evaluate the feasiblity of alumina production in Ghana to replace imported alumina for the production of aluminum. It spells out the conditions which led to the existing bauxite-alumina-aluminum trade in the country. The structure of the economy of Ghana is examined to show the contributions of the important sectors to the total income of the country, and its dependence on a few export commodities for revenue. The plan to build a dam for the generation of hydroelectric power was linked to the establishment of an integrated aluminum industry based on the exploitation of domestic bauxite reserves. As the country could not finance the project alone, foreign assistance was sought. VALCO, a subsidiary of Kaiser and Reynolds, was formed to undertake the project. The agreement reached with VALCO was that a smelter would be built to use imported alumina for ten years, during which time a refinery would be built to feed the smelter from domestic sources. However, after ten years this could not be achieved, and the smelter continues to use imported alumina. A model of the world aluminum economy is used for analyzing the sensitivity of price to production and consumption expansion. The results show that industry demand is sensitive to the level of industrial activities in the developed countries, and less sensitive to the own price and cross price variables of aluminum in both the short and long run. On the other hand, supply is inelastic to the own price and the rate of capacity utilization in the short run, but elastic to both variables in the long run. An appraisal of opening a bauxite mine and an alumina refinery at Kibi is undertaken. The results show the levels of bauxite and alumina prices and the costs of construction at which the project is feasible. The shadow values and weights used are permittd to vary with changes in the economy's foreign trade and the balance of payments.
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Antoniassi, Juliana Lívi. "A difração de raios X com o método de Rietveld aplicada a bauxitas de Porto Trombetas, PA." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/3/3134/tde-23112010-090249/.
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O projeto enfocou a aplicação da difração de raios X (DRX) associada ao método de Rietveld na determinação quantitativa da composição mineralógica de bauxitas de Porto Trombetas, PA. Os resultados obtidos foram comparados com aqueles de outras ferramentas de determinação mineralógica, especificamente métodos tradicionais de caracterização de minérios e espectroscopia Mössbauer, além da correlação direta com dados de análises químicas que, atualmente, são utilizados no controle de pesquisa e processamento de bauxita. Preliminarmente, definiram-se tipos mineralógicos de minério com o recurso de análise por agrupamento de dados de difração de raios X para um conjunto de 60 amostras, englobando materiais da pesquisa mineral e do beneficiamento de bauxita pela Mineração Rio do Norte (MRN). Esse recurso permitiu otimizar o conjunto de amostras para o estudo e facilitar a definição de seqüências específicas de refinamento pelo método de Rietveld para grupos de amostras com composição mineralógica similar. A DRX-Rietveld mostrou-se relevante e eficiente no estudo de bauxitas, sendo obtidos satisfatórios valores de indicadores estatísticos de refinamento (GOF e Rwp), além de elevada correlação linear com as demais metodologias aplicadas, particularmente no que se refere aos maiores constituintes das amostras, essencialmente gibbsita e argilominerais. No caso de óxi-hidróxidos de ferro (basicamente hematita, goethita e uma fase de Fe3+ de baixa cristalinidade), com proporções inferiores a 20% nas amostras, verificou-se que parte desses minerais praticamente não foi detectada por DRXRietveld visto o grau de cristalinidade dessas fases, conforme observado por microscopia eletrônica de varredura e espectroscopia Mössbauer.This research concerns the application of X-ray diffraction (XRD) with Rietveld method in order to determinate the mineralogical composition of bauxites from Porto Trombetas, PA. The results were compared with the mineralogical composition obtained by mineral separations supported by chemical analysis and Mössbauer spectroscopy, as well as correlated with XRF chemical analysis and selective dissolution chemical analysis, that routinely support bauxite mineral research, mining operation as well as mineral processing. Previously, a definition of mineralogical types was provided by cluster analysis of a 60 samples set of diffractograms, corresponding to geological research and beneficiation products from Mineração Rio do Norte (MRN). This tool simplified the analysis of a large number of data for the study and helped to establish the Rietveld refinement strategies for clusters of samples with similar mineralogical compositions. XRD with Rietveld method showed to be relevant and efficient for bauxite study, giving satisfactory statistical evaluation parameters (GOF and Rwp), besides high linear correlation with the others mineralogical methods for the major minerals, essentially gibbsite and clay minerals. For oxi-hydroxides minerals (basically hematite, goethite and a low crystallinity Fe3+ phase), with proportions bellow 20 percent of the samples, it could be seen that part of these minerals was not detected by XRD and so not evaluated by Rietveld quantification method, since they present low crystallinity as observed by scanning electron microscopy and Mössbauer spectroscopy.
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Faria, Robersio Marinho de. "Estudo da dispersão das propriedades físico-químicas em blocos de alumina marrom obtida por eletrofusão." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/97/97134/tde-29032017-091850/.
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Tendo em vista a natureza finita dos minerais naturais, torna-se evidente a necessidade de utilizarmos este recurso de maneira estratégica. Desta forma, diversas pesquisas vêm sendo desenvolvidas principalmente nas áreas químicas, metalúrgicas e mineralógicas desde as etapas de extração, beneficiamento, aplicação e reutilização dos resíduos de minérios. Portanto, é extremamente importante a intensificação dos estudos para aumentar o conhecimento quanto às características e propriedades físico-químicas destes minerais, visando melhorar o seu aproveitamento e longevidade das jazidas naturais, como as fontes de bauxita, que é a principal matéria-prima para a produção de óxido de alumínio fundido. Na sua forma cristalina mais comum, denominada coríndon, ou óxido de alumínio ?, sua baixa condutividade elétrica, baixo calor específico, alta condutividade térmica, alto ponto de fusão, elevada dureza e resistência mecânica, o torna adequado para uso em produtos refratários, cerâmicos e abrasivos tais como, lixas, rebolos, ferramentas de corte e de polimento. Na síntese deste produto as principais impurezas que afetam a qualidade dos grãos são Fe, Si, Ca, K, Na e Zr, oriundas da matéria prima bauxita e da carta de mistura, composta por ilmenita, limalha de ferro, carvão vegetal e coque de petróleo. Desta forma, o presente trabalho assumiu o objetivo de estudar a dispersão das propriedades físico-químicas em blocos de alumina fundida marrom obtida em fornos Higgins a arco por eletrofusão, produzidos na Saint-Gobain Abrasivos, unidade de Lorena, SP. Por fim, foram utilizadas técnicas de caracterização físico-químicas de difratometria de raios X (DRX), análises químicas de fluorescência de raios X (FRX), ensaio de dureza Knoop e caracterização microestrutural via (MEV/EDS). Desta forma, foi definido o mapeamento composicional nos blocos de alumina eletrofundida marrom, que servirão como referência técnico-científica para subsidiar ações de melhoria deste produto, em decorrência do avanço do estado da arte deste referido assunto.The mineral ores are not renewable sources and we need to use it in the best way possible. In this way, a large number of researches are being developed around the world aiming the improvement of current methods of production mainly in chemical, metallurgy, mineralogical from the steps of extraction, processing, application and reuse of waste ore. Therefore, it is extremely important to intensify the studies to increase the knowledge about the characteristics and physicochemical properties of these minerals, in order to improve their utilization and longevity of natural deposits, such as sources of bauxite, which is the main raw material to product aluminum oxide fused. In its most common crystalline form, called corundum or ?-aluminum oxide, its low electrical conductivity, low specific heat, high thermal conductivity, high melting point, high hardness and mechanical strength, making it suitable for use as refractories, ceramics and fine or coarse abrasives. The synthesis of this product major impurities that affect quality of grain is Fe, Si, Ca, K, Na and Zr, derived from the raw material bauxite and the mixture chart consisting of ilmenite, iron filings, charcoal and coke oil. Thus, this shows the dispersion of physicochemical properties of brown fused alumina blocks produced by eletrocfusion at Higgins furnace process in the company Saint Gobain Abrasivos, Lorena- SP. Finally, the samples were physicochemical analyzed by X ray diffraction (XRD), chemical analyses by X ray fluorescence (XRF), hardnes using Knoop method, microstructural characterization by (SEM). The results of this work show a compositional gradient map of the fused alumina block; that shows the main physicochemical differences into the block, to support changes in the alumina production process; and it is also important to improve the actual state of art of this particular theme.
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Kopittke, Peter Martin. "Limitations to plant root growth in highly saline and alkaline bauxite residue /." [St. Lucia, Qld.], 2004. http://adt.library.uq.edu.au/public/adt-QU20040913.094109/index.html.
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VILLAR, LUCIO FLAVIO DE SOUZA. "RESEARCH ON CONSOLIDATION AND DESICCATION OF BAUXITE MINING AND INDUSTRIAL PROCESSING WASTES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2002. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=3528@1.
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOEste trabalho apresenta a metodologia usada no acompanhamento do adensamento e do ressecamento de resíduos de mineração e processamento de bauxita, as lamas vermelhas. A proposta foi investigar métodos para obtenção de informações sobre efeitos do ressecamento solar no comportamento da lama, buscando identificar a transição da fase saturada para a não saturada destes materiais. A pretensão foi facilitar a incorporação destes efeitos a métodos de análise do ciclo de vida útil de reservatórios de disposição de rejeitos de mineração e processamento depositados sob forma de lama, e que em geral só consideram os recalques por peso próprio e/ou lançamento de novas camadas. Será possível, então, chegar a uma previsão mais realista de sua capacidade de armazenamento e de suas características finais, dados importantes para executar projetos mais racionais de reabilitação do depósito. Foram estudados cinco tipos de resíduos diferentes. Um, é constituído pelos rejeitos de lavagem de bauxita de uma mina localizada no estado do Pará, sendo composto somente de grãos sólidos e água. O segundo tipo é o resultado do processamento deste primeiro material, uma lama com fluido altamente básico (pH 14). Os outros dois são rejeitos de processamento de bauxitas de duas regiões diferentes do estado de Minas Gerais: um da região de Poços de Caldas, e o outro, da região de Ouro Preto, ambos com pH em torno de 14. Este último material, da região de Ouro Preto, é que foi utilizado em estudos anteriores da PUCRio. O último resíduo analisado é produto de uma neutralização feita nesta mesma lama de Ouro Preto antes de sua disposição final. Foram com estes dois últimos rejeitos que se realizou a maior quantidade de testes e análises, e eles, então, se constituíram os objetos principais da pesquisa. Foram executados ensaios de adensamento com deformação controlada, determinação de curvas características de sucção e secagem através de diferentes técnicas (papel filtro, tensiômetros etc); caracterizações especiais e ensaios de ressecamento em caixas de dimensões variadas, procurando simular o efeito da radiação solar nestes rejeitos, e ensaios de campo (medição de poropressões e coleta de amostras). Metodologias de execução e interpretação destes testes para estes materiais não usuais são propostos. O seu comportamento na transição da fase saturada para a não saturada foi acompanhado, tanto com relação à variação de volume quanto de resistência. Modelos empíricos são sugeridos, e podem ser usados para uma primeira previsão dos efeitos da exposição à secagem.
This work presents the methodology used to study the consolidation and desiccation of bauxite wastes from mining and industrial processing. The aim is to understand the geotechnical behavior of these wastes launched as slurries in reservoirs and then, let do dry under solar exposure. Five types of residues are here considered. The first is an inert waste resulting from washing of bauxite in mining operations run in the North of Brazil. The other four are wastes resulting from the physicochemical treatment of the bauxite in alumina production industrial plants. Such treatment follows the worldwide known Bayer process. Three of these four wastes, which are usually named as red muds, are disposed with pH around 14. The other one is disposed after neutralization with sulfuric acid, under a pH around 8. Data of solar exposure effects on the muds behavior was obtained in order to determine parameters to be incorporated into consolidation models. Therefore, an improvement on predictions of the life cycle of the wastes reservoirs can be achieved. To study the transition between the saturated phase to the unsaturated one and to determine the geotechnical and geomechanics characteristics of the wastes, an extensive laboratory testing program was performed. This included CRD tests, monitored physical model tests and the determination of water retention curves for the wastes from fully wetted to dry conditions. Laboratory results are compared with those of field monitoring programmes and some empirical models are proposed.
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Wong, Jonathan Woon-Chung. "Sodium release characteristics and revegetation of fine bauxite refining residue (red mud)." Thesis, Wong, Jonathan Woon-Chung (1990) Sodium release characteristics and revegetation of fine bauxite refining residue (red mud). PhD thesis, Murdoch University, 1990. https://researchrepository.murdoch.edu.au/id/eprint/52497/.
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The revegetation of bauxite refining residue, red mud, produced from alumina refining is extremely difficult because of the high amount of Na in the residue especially in the desilication product (DSP). The high Na content imparts to red mud highly saline and sodic characteristics. The present study was to develop means to revegetate red mud through the control of Na release and the utilization of acidic and organic ameliorants together with tolerant plant species.
Neutralization of red mud with HCl showed that the DSP, which was found to be a zeolite mineral akin to nosean, decomposed at pH between 5.4 and 7.0 and with a maximum Na release of 98.6 meq/100 g occurring at pH 5.4. At pH >7, the release of Na was due to the cation exchange between Na+ in red mud with H+ , and Ca2+ from dissolution of calcite. At pH between 5.4 to 7.0, Na release from the DSP was due to acid hydrolysis.
The cation exchange capacity (CEC) obtained with monovalent cations was higher than with divalent cations. About 83 meq Na /100 g red mud could be displaced by K+ with repeated washings. Divalent cations could only displace about one third of the Na. The external CEC of red mud was estimated to be 15.4 meq/100 g while the internal CEC of red mud was 49.6 meq/100 g. A selectivity sequence for red mud was established: K > Li > NH4 > Ba ≥ Ca> Mg at a cation fraction on red mud ≥ 0.2.
Four first-order reactions could be used to describe the release of Na from Na-K and Na-Ca exchanges in red mud with a total release of 61 and 31 meq/100 g red mud respectively. Sodium located in the external sites was released in about 6 h and 3 days for K and Ca exchange respectively. The final rates of Na desorption from the DSP were low for both exchanges. This indicates that the sodicity of red mud may increase with time.
A glasshouse pot trial was used to investigate the effectiveness of copperas (FeSO4) and gypsum (CaSO4) for red mud reclamation. Copperas was effective in reducing the EC and Na content of red mud, but gypsum resulted in lower pH and higher Ca content at application rates of 5% and 8% w/w). Seed germination and dry weight yield of Agropyron and Cynodon were enhanced with 8% gypsum or 5% and 8% copperas amendments, but the performance of Agropyron was found to be better than that of Cynodon. Addition of sewage sludge to 5% copperas and 8% gypsum-amended red mud caused an additional reduction of the pH, EC and Na content of red mud. Gypsum-sewage sludge amendment was more effective in reducing pH and ESP, increasing Mg and P04 content, and resulted in lower soil Al content. Yields of Agropyron obtained in red mud receiving 8% gypsum and 16% sewage sludge were significantly higher than in copperas and sewage sludge-amended red mud. A minimum leaching of 84 mm was required to reduce the pH, EC, Na and Ca content of gypsum-sewage sludge-amended red mud, and a supplementation of N, P, and K fertilizer was recommended for the growth of Agropyron in red mud amended with gypsum and sewage sludge.
In field trials, the same rate of gypsum and sewage sludge amendment also reduced the pH, alkalinity, and ESP of red mud, but was less effective than the same rate in the glasshouse trial. Dry weight yield and plant covering percentage of Agropyron in plots receiving 38.5 t/ha (8%) gypsum and 77 t/ha (16%) sewage sludge were significantly increased but the yield was only about half that of plots having a surface placement of sandy soil. Tissue analysis of Agropyron grown in gypsum and sewage sludge-amended red mud indicates N and Mg levels were marginal, while Mn appeared to be insufficient.
Varying the gypsum to soil volume ratio (G:V) by amending with 38.5 t/ha gypsum and 77 t/ha sewage sludge to different depths of 5, 10, and 20 cm had no significant effect on the pH, EC, and ESP of red mud. However, increasing the application rate to 77 t/ha gypsum and 154 t/ha sewage sludge but maintaining the same G:V ratio by incorporating to a depth of 20 cm was effective in reducing the pH, alkalinity, and ESP of red mud. A higher amount of Ca and Mg was found in soil extending to a greater depth. This significantly enhanced the dry weight yield and plant covering percentage of Agropyron.
The increased yield following gypsum and sewage sludge amendment was attributed to improved soil physical properties. Addition of sewage sludge significantly reduced the bulk density, particle density and increased the total porosity. Both sewage sludge and gypsum contributed to increases in air-filled porosity and saturated hydraulic conductivity. The improved soil structure and hydraulic property were found to be significantly correlated with the dry weight yield.
The present study indicates that following the removal of Na in the external exchange sites, the use of gypsum and sewage sludge was effective in red mud reclamation. The slow released Na with time can be counteracted by the addition of an excess amount of gypsum, which will require periodic soil monitoring. This management strategy indicates direct revegetation is feasible and no heavy earth moving techniques are required.
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Fassio, Joseph Michael. "Geochemical Evolution of Ferruginous Bauxite Deposits in Northwestern Oregon and Southwestern Washington." PDXScholar, 1990. https://pdxscholar.library.pdx.edu/open_access_etds/3821.
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Ferruginous bauxite deposits developed from flows of the Columbia River Basalt Group in northwestern Oregon and southwestern Washington. Samples of the iron pisolite and the gibbsite nodular zones from the upper portion of the weathering profile of drill core from Columbia County, Oregon and Cowlitz County, Washington, were analyzed by instrumental neutron activation. The mineralogy was determined using Xray diffraction and Mossbauer spectroscopy.
The gibbsite nodular zone is above the clay-rich saprolite or relic basalt zone. The nodules contain relic vesicles and well preserved relic plagioclase microlites. Gibbsite occurs with poorly crystalline goethite and hematite in the gibbsite nodular zone. Clays are absent in this part of the profile .
The iron pisolite zone is at the top of the profile above the gibbsite nodular zone. Both maghemite and goethite pisolites occur in the lower part of the zone while maghemite pisolites are dominant in the upper part of the pisolite zone.
The parent flow is the Frenchman Springs Member of the Wanapum Basalt for the Columbia County profile and the Pomona Member of the Saddle Mountains Basalt for the Cowlitz County profile.
Distribution of the major, minor and trace elements through the profile shows three distinct sympathetic patterns consisting of lanthanide elements and Na; As, Sbi Th, Hf, and Ta; and transition metals Fe, Ti, V, and Cr.
Ratios between the high-field strength elements Ta and Hf are nearly constant through the profile, and Hf appears to be the least mobile elements of the elements analyzed in the profile. Ratios of other elements were calculated against Hf, based on the assumption that it has remained largely immobile during weathering, to show element enrichment and depletion in the profile independent of mass-volume changes. Transition metals and Al show a progressive depletion through the upper gibbsite nodular and iron pisolite zone due to leaching in the profile. Lanthanide elements (except Ce), As, and Sb show an obvious enrichment in the iron pisolite zone relative to the gibbsite nodular zone.
Volume reduction during weathering was calculated based on the immobility of Hf. In the gibbsite nodular zone, the volume reduction calculated for bulk samples is greater than for gibbsite nodule separates suggesting that a greater volume reduction occurred the matrix material surrounding the nodules. Ratios between gibbsite nodules and parent basalt of the immobile elements Hf, Ta, Fe, Ti, Th and Cr suggest that the nodules, where the relic textures are preserved, have undergone volume reduction. Based on the immobility of Hf, the gibbsite nodules lost approximately 40% of the original volume. The volume factors based on the immobility of Hf show that the pisolite zone experienced a greater volume reduction than the gibbsite nodular zone.
Absolute gains and losses relative to the parent basalt show the following relative order of depletion: Na > La > Eu > Sm > Co > Mn > Ce > Sc > Ta > V > Cr > Lu > Th > Fe > Ga > Al. The lesser mobility of Ce and Lu relative to other lanthanide elements suggests fractionation of lanthanide elements in the bauxite profile. Aluminum is both enriched and depleted at different depths in the gibbsite nodular zone suggesting that Al is mobilized from the matrix and possibly the pisolite zone into Al enriched gibbsite nodules.
Volume reduction and destruction of relic textures in the pisolite zone is accompanied by small-scale mobilization of Th, Cr, Fe, Hf, Ga, Sc, and Ta during the formation of iron pisolites.
Formation of the iron pisolite zone above the gibbsite nodular zone may indicate a change in climate from a heavy year round to a seasonal rainfall pattern.
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PRADO, Cinara Machado Rodrigues do. "Produção e Caracterização de Biocombustíveis por Craqueamento de Óleo Vegetais via Catálise com Bauxita." Universidade Federal de Goiás, 2009. http://repositorio.bc.ufg.br/tede/handle/tde/1057.
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Previous issue date: 2009-08-06In this work, raw bauxite, thermally activated calcined bauxite, calcined bauxite underwent acid treatment were the catalysts tested by its potential in the thermal catalytic cracking reaction looking forward to the production of biofuels from commercial soybean oil as an alternative to fossil fuels. The materials were characterized by the techniques ICP-OES, infrared spectroscopy, thermal analysis, X-ray diffraction and textural analysis. The chromatographic analysis of the biofuels obtained by cracking of commercial soybean oil showed hydrocarbon compounds such as alkanes, alkenes and aromatics, as well as some oxygenated compounds such as carboxylic acids, ketones and alcohols. The products generated by the thermal catalytic cracking process with thermally activated calcined bauxite showed better results than the thermal cracking products because of the low quantity of acids present, which provided biofuels with a lower acidity index, and absence of acrolein. Therefore, the catalyst which was used demonstrated activity in the secondary cracking process, in which fatty acids decompose and give rise to hydrocarbons. The cracking tests with raw bauxite generated a lower biofuels yield and significant amount of solid product and residual oil making unfeasible the process. In order to evaluated the potential of used industrial waste sources for production of alternative fuels, the cracking of the waste vegetable oil studied together with the optimum of the reaction conditions obtained satisfactory result in the gaseous and liquid yield and percentage of crude biofuels generated. The biofuel presented similar composition observed in the biofuels obtained in thermal catalytic cracking of xv commercial soybean oil. This proved that the thermal catalytic cracking process is an alternative solution for the reutilization of waste vegetable oil and fats, both, when discarded inadequately can become environment pollutants
Neste trabalho, a bauxita in natura , bauxita calcinada termo ativada e bauxita calcinada tratada com ácido clorídrico foram os catalisadores avaliados quanto ao seu potencial frente à reação de craqueamento termocatalítico do óleo de soja comercial para obtenção de biocombustíveis alternativos aos combustíveis fósseis. Estes materiais foram caracterizados através das técnicas de ICP-OES, espectroscopia no infravermelho, análise termogravimétrica, difração de raios X e análise textural. As análises cromatográficas dos biocombustíveis obtidos por craqueamento do óleo de soja comercial evidenciaram a presença de hidrocarbonetos - tais como alcanos, alcenos e aromáticos - e compostos oxigenados como ácidos carboxílicos, cetonas e alcoóis. Os produtos formados no processo de craqueamento termo-catalítico com bauxita calcinada termo ativada apresentaram-se melhores resultados do que os obtidos no craqueamento térmico, devido à menor quantidade de ácidos carboxílicos presentes, o que proporciona a obtenção de biocombustíveis com menor acidez, e isento de acroleína. Portanto, este catalisador demonstrou atuar no processo de craqueamento secundário, no qual os ácidos graxos se decompõem originando hidrocarbonetos. Os testes de craqueamento com bauxita in natura geraram baixos rendimentos de biocombustíveis brutos e na formação de quantidades significativas de produto sólido e óleo residual, tornando o processo inviável. A fim de avaliar o potencial de utilizar fontes de resíduos industriais para se obter combustíveis líquidos alternativos estudouse o craqueamento de óleo vegetal residual empregando as condições reacionais otimizadas, obtendo resultados satisfatórios em rendimento de produtos líquidos e gasosos e o percentual de biocombustível bruto, sendo que o biocombustível obtido apresentou composição similar aos obtidos no craqueamento termo-catalítico de óleo de soja comercial. Isto mostra que o processo de craqueamento termo-catalítico constitui uma alternativa para reutilização de óleos e gorduras residuais, os quais, quando descartados inadequadamente podem vir a se constituir poluentes ambientais
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Danielsson, Lina, and Lisa Söderberg. "Removal of chromium in wastewater with natural clays in southern Malawi." Thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-199061.
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To live a healthy life, people all around the world need access to safe water. A lot of industries,together with the fast growing population in Blantyre, a city in southern Malawi, pose a threat to theaccess of safe water for the citizens. Several of the industries in Blantyre release contaminated waterto the nearby streams. One serious pollutant emitted from a match factory is chromium (Cr),especially in the occurrence of Cr(VI) which is carcinogenic for humans. Earlier studies have shownthat the concentration of chromium in the match factory’s wastewater was higher than WHO:sguidelines. It has also been published that natural clay minerals can be used for adsorption of Cr(III).This study investigates the removal of Cr(VI) through the adsorption of Cr(VI) to clay minerals or byreduction of Cr(VI) to Cr(III) which is precipitated from solution.The laboratory work performed in this study includes both experiments for adsorption of Cr(VI) andreduction of Cr(VI) to Cr(III). The reducing agents investigated were two clays and Fe(II) sulfate. Foradsorption of negatively charged Cr(VI) compounds, the two clays where used at lower pH and themineral bauxite was also tried as adsorbent agent. Wastewater from the match factory was dilutedand mixed with the removal agents and the concentration of total chromium was measured beforeand after the mixing process. For the agent with highest potential for Cr(VI) removal, the optimalconditions due to pH, dosage of agents and contact time were inspected.None of the investigated reducing agents served its purpose which means that no Cr(VI) was reducedto Cr(III) in this study. The adsorption of Cr(VI) with clay 1 at lower pH was also not successful, butthe adsorption worked for clay 2 at lower pH and for bauxite. In the experiments bauxite adsorbed ahigher amount of Cr(VI) than clay 2. The adsorption with bauxite turned out to be independent interms of pH. The optimal conditions for bauxite in the experiments were with a dosage of 3.5 gbauxite in 50 mL wastewater and a contact time of 40 minutes. The results showed an adsorption of93 percent of total chromium with bauxite at optimal conditions.
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Massola, Camila Peres. "Flotação reversa da bauxita de Miraí - MG." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/3/3134/tde-25092008-094000/.
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Este trabalho apresenta os resultados de pesquisas realizadas com rejeitos de bauxitas, provenientes da usina operada pela Companhia Brasileira de Alumínio CBA, em Itamarati de Minas, MG. O circuito industrial da CBA tem operações de escrubagem, peneiramento, deslamagem e separação de minerais pesados, através de um circuito de concentração em espirais Reichert e de separação magnética. Porém, ainda são perdidos importantes teores de alumina aproveitável na fração fina, que é atualmente considerada rejeito. A flotação reversa da sílica insolúvel presente neste rejeito, seguida de separação magnética do produto deprimido, permite recuperar gibbsita, e produzir areia para construção civil e manutenção de estradas. O concentrado magnético pode ser usado como aditivo de carga na produção de cimento Portland. Portanto, o beneficiamento desta fração, além da importância econômica, vem contribuir para a conservação dos recursos minerais. Através de ensaios em bancada e em usina piloto, este trabalho demonstra a aplicabilidade deste processo a bauxitas de Miraí, sudeste de Minas Gerais. Após a separação magnética, obtém-se um concentrado com recuperações de 28,8% em massa e 81,2% metalúrgica, com 54% de alumina aproveitável e relação Al2O3/SiO2 de 12,6. Os resultados aqui obtidos indicam viabilidade para aplicação industrial do processo desenvolvido.This research presents the results achieved by the author in recovering gibbsite from industrial bauxite tailings. The tailings samples were provided by Companhia Brasileira de Alumínio CBA, from it´s Itamarati de Minas, MG plant. The CBA´s Itamarati de Minas plant has a complete circuit of scrubbing, desliming, and heavy minerals separation in spiral concentrators, complemented by high intensity magnetic separation, but it still loses the values contained in the fine fraction of the beneficiated ore, which currently consists of a tailing. Reverse flotation of the insoluble silica present in this tailings stream, followed by magnetic separation of the depressed product, allows to recover gibbsite, and produces silica sand, which can be used in civil construction work and road maintenance. The magnetic concentrate can be used as a charge additive to Portland cement production. Thus, the beneficiation of this fraction is important both economically and for mineral resources conservation. Through experimentation on bench and at pilot plant scale tests, this work explores the feasibility of such a process to the bauxites from Miraí, southeastern Minas Gerais state. After magnetic separation, the concentrate reached available alumina grades of 54% at pilot plant, with 28.8% mass recovery and 81.2% metallurgical recovery, with a Al2O3/SiO2 ratio of 12.6. This shows viability for industrial scale application of the process.
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FROTA, Luis Eduardo Medeiros. "Avaliação do uso de diferentes fontes de bauxita no processo de produção de óxido de alumínio." Universidade Federal de Campina Grande, 2012. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/256.
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O Oxido de alumínio, Al2O3, comumente chamado de alumina se trata de um composto químico de ampla utilização na indústria estando presente em pastas de dente, tinta, aditivos para tratamento de água dentre outros. Porém sua principal utilização é na indústria do Alumínio onde representa a principal material prima para a obtenção deste metal. A maior parte do Oxido de alumínio produzido no mundo hoje tem como fonte primária a Bauxita. O Alumínio está presente nesse minério na forma de óxi-hidroxidos de alumínio onde os principais são: gibbsita Al(OH)3, diasporo AlO(OH) e boehmita AlO(OH). O processo de refino para obtenção da Alumina a partir da Bauxita mais comumente aplicado atualmente é o processo Bayer no qual o minério é atacado com uma solução cáustica a base de hidróxido de sódio (NaOH) a fim de solubilizar o Alumínio para posterior recristalização. As várias etapas do processamento do minério são definidas e ajustadas em virtude das peculiaridades da bauxita utilizada como, por exemplo, composição química, granulometria e composição mineralógica. Bauxitas com características diferentes pedem processamento diferenciado. Com a demanda por alumina crescente, novas fontes de Bauxita necessitam ser exploradas e uma preocupação é que tipo de mudanças um minério de uma nova fonte pode causar ao processo. Este trabalho teve como objetivo avaliar a bauxita proveniente de uma nova fonte seus impactos no processo servindo como embasamento para tomada de decisão sobre a viabilidade da abertura de uma nova mina e um aumento de capacidade de processamento por parte da Refinaria. Caracterização química e simulação do processo Bayer em bancada mostraram que o material proveniente da nova fonte de bauxita não apresenta diferenças significativas em relação ao minério já utilizado embasando assim os investimentos para abertura e uma mina com capacidade de 4 milhões de toneladas de minério por ano e um aumento de capacidade de produção na refinaria de 2 milhões de toneladas de alumina ao ano.
The aluminum oxide, Al2O3, commonly called alumina it is a compound widely used in chemical industry and is present in toothpastes, ink, water treatment additives and others. However aluminum industry is the principal client where is the main raw material for production of this metal. Most of the aluminum oxide produced today has Bauxite as the main source. The aluminum is present in this ore as oxi-hydroxides which are the main: gibbsita Al(OH)3, diasporo AlO(OH) and boehmita AlO(OH). The refining process for obtaining alumina from bauxite most commonly is the Bayer Process where ore is attacked with a caustic solution based on sodium hydroxide (NaOH) in order to solubilize the aluminum subsequent to recrystallization. The various steps of ore processing are set and adjusted based on the characteristics used as, eg, chemical, mineralogical composition and particle size. Bauxites with different characteristics require different processing. With the increasing demand for alumina, new bauxite sources need to be explored and to know what kind of changes new ore source could require is fundamental. This work aimed to evaluate possible impacts caused by a new source and use this information to evaluate a new mine operation and increase processing capacity at Refinery. Chemical characterization and reproduction of some stages of the Bayer process in bench showed that material from the new source of bauxite does not differ significantly in relation to the first ore confirming investments for opening a anew mine with a capacity of 4 million tons per year supporting production increase refinery production capacity of 1,5 million tons of alumina per year.
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Ludwig, Ralph. "A study of post-dehydration bonding and ion adsorption in a bauxite waste /." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=74635.
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Consideration of alternative methods for the disposal of bauxite waste by the aluminum industry has generated interest in the ability of bauxite waste solid constituents to attain a certain degree of physical integrity upon drying to yield a material of suitable strength properties. This thesis study seeks to provide insight into the development of physical integrity in bauxite waste through elucidation of potentially operative bonding mechanisms in a selected Jamaican bauxite waste which is observed to dry to a material of relatively high post-dehydration strength properties. Interest in the ability of bauxite waste solids to attain a certain degree of physical integrity extends to an application, proposed in this study, involving the potential use of bauxite waste as a contaminant stabilization/solidification medium. Efforts at facilitating elucidation of potentially operative bonding mechanisms are accomplished by means of a comparative study involving a second bauxite waste derived from Guinea bauxite which, despite its similar mineralogy to the selected Jamaican bauxite waste, was observed to dry to a material of low post-dehydration strength properties. Results obtained from the study revealed the apparently important role of hydroxylated oxide/hydrous oxide surfaces of high specific surface in governing the development of physical integrity.A parallel study concerned with the ion adsorption properties of Jamaican bauxite waste was as well conducted in efforts to further aid in establishing the potential for use of bauxite waste as a contaminant stabilization/solidification medium. Adsorption tests were conducted using four ions (Cl$ sp-$, SO$ sb4 sp-$, K$ sp+$, and Pb$ sp{++}$) selected on the basis of valency and sign of charge. The results indicated the marked ability of the bauxite waste solids to adsorb lead both below and above the measured point of zero charge (PZC) of the bauxite waste solids. The results also indicated sulphate, contrary to chloride, was readily adsorbed provided it was added as its acid. When added as its salt (Na$ sb2$SO$ sb4$), no sulphate adsorption was observed even at pH values well below the PZC. The postulated chemisorption-type interaction of lead and other heavy metals with hydroxylated oxide/hydrous oxide surfaces suggests that certain bauxite wastes, particularly those which exhibit high post-dehydration strength properties, may be well suited for use in contaminant stabilization/solidification applications.
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Collins, Sarah. "Long-term survival of Phytophthora cinnamomi in rehabilitated bauxite mines and adjacent jarrah." Thesis, Collins, Sarah (2006) Long-term survival of Phytophthora cinnamomi in rehabilitated bauxite mines and adjacent jarrah. PhD thesis, Murdoch University, 2006. https://researchrepository.murdoch.edu.au/id/eprint/32426/.
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Ward, Samuel Campbell. "The use of the fine residue from bauxite refining as a soil amendment." Thesis, Ward, Samuel Campbell (1986) The use of the fine residue from bauxite refining as a soil amendment. PhD thesis, Murdoch University, 1986. https://researchrepository.murdoch.edu.au/id/eprint/52560/.
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Large quantities of the alkaline residue from bauxite refining are produced each year in Western Australia. If alternative uses could be found for the residue this would decrease the amount of land required for storing the residue and reduce the problems of managing these storages. This study investigated the use of the fine fraction of the residue (red mud) as a soil amendment for sandy soils. Red mud has a high capacity to retain water and nutrients, particularly phosphorus. Amending sandy soils of the Swan Coastal Plain with red mud could increase their productivity and reduce the leaching of phosphorus fertiliser. The leaching of phosphorus fertiliser from these sandy soils has been directly implicated as the cause of eutrophication of coastal water bodies (Dept. Cons. Env. W.A., 1984).
The growth and persistence of annual legume pastures on sandy soils amended with a range of levels of red mud or red mud ameliorated with gypsum (red mud/gypsum), up to 2000 t/ha, was investigated at four sites on the Swan Coastal Plain. The fertiliser requirements of the legume pastures growing on amended soils were determined. The physical and chemical characteristics of the amended soils and changes in these characteristics with time were investigated. The concentrations of a range of elements in the plants growing on amended soils were determined to identify possible nutrient deficiencies or potentially hazardous levels of elements.
On well-drained, coarse sands amendment with red mud, neutralised with 5% gypsum, increased total pasture growth by up to 100%. Increases in the legume component of the pasture were even greater. Amendment with 500t/ha or more of red mud/gypsum, in the top 20-30 cm of soil, is recommended for these sands. These levels of red mud/gypsum amendment significantly increased the water-holding capacity of the sands and reduced their water repellence. Consequently yields were highest and legume pastures should persist.
On low-lying, coarse, acid sands amendment with red mud/gypsum did not always increase pasture growth. At 500 t/ha, or less, pasture growth was sometimes increased but never decreased by amendment. On these sands 200 t/ha of red mud/gypsum, or a minimum consistent with controlling the loss of phosphorus from these soils, is recommended. When 200 t/ha of red mud/gypsum was applied, pasture yields were always high, legume seedlings survived well during extended dry periods in autumn, soil pH was raised to about 6.5 and there should be sufficient red mud/gypsum to reduce phosphorus leaching.
Pastures growing on soils amended with red mud/gypsum required phosphorus and potassium fertiliser, but only at normal agricultural application rates. There was a response to a foliar application of manganese fertiliser, in some cases.
With one exception, there was no evidence of any elements accumulating to levels toxic for animals or plants in pastures growing on soils amended with red mud/gypsum. The exception was molybdenum, when high rates of molybdenum fertilisers were applied. Molybdenum containing fertilisers should not be applied to soils amended with red mud.
After 3-4 years in the field, soils amended with red mud/gypsum were sufficiently leached to be classed as non-saline, or at worst mildly-saline, and non-sodic. At levels of red mud/gypsum application of 200-500 t/ha or more, the pH values of the amended soils were around 8.3 indicating that they were being buffered by calcium carbonate.
Although red mud/gypsum amendment was generally beneficial for pasture growth, the costs of amendment are too high to be economic. Large-scale amendment of soils is only likely if the taxpayer or alumina companies bear the majority of the cost. Red mud/gypsum amendment deserves more consideration as a strategy to reduce the inflow of phosphorus into the Peel Inlet and Harvey Estuary, Western Australian to overcome the eutrophication problems.
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Morin, Guillaume. "Cristallochimie du fer dans les bauxites : application à l'étude du gisement de Bidi-Koum (Guinée)." Paris 7, 1994. http://www.theses.fr/1994PA077070.
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Des donnees cristallochimiques nouvelles ont ete obtenues sur des materiaux d'alteration lateritique, parfaitement situes dans leur contexte petrologique (bauxite de bidi-koum, guinee): (1) l'existence de lacunes cationiques, compensees par des protons, a ete mise en evidence dans les hematites alumineuses alpha- #y#/#3(fe#1#-#xal#x)#2#-#y#/#3o#3#-#y(oh)#y et les goethites alumineuses alpha- #y#/#3(fe#xal#1#-#x)#1#-#y#/#3o#1#-#y(oh)#1#+#y naturelles. Le taux de lacunes y/3 constitue une signature des precurseurs et des temperatures de cristallisation. Par exemple, dans les bauxites etudiees, le caractere lacunaire marque des hematites (18-28 %mole ) montre qu'elles resultent du vieillissement de precurseurs de type gels ferriques ou ferrihydrite dans des conditions de forte sursaturarion en fer. En revanche, le caractere faiblement lacunaire des goethites alumineuses (10-13 %mole ) reflete une dissolution partielle d'un precurseur gel, ferrihydrite ou hematite et une croissance cristalline en milieu faiblement sursature. (2) la substitution isomorphe de al#3#+ par fe#3#+ dans la gibbsite alpha-al(oh)#3 est limitee a moins de 250 ppm fe, par des contraintes structurales au sein du feuillet dioctaedrique, qui conduisent a une occupation trois fois moindre de l'octaedre le plus distordu axialement. En revanche la substitution fe-al dans la boehmite gamma-alooh ( 1% feooh) pourrait constituer un traceur geochimique sensible et meriterait d'etre prise en compte pour le calcul des champs de stabilite dans le systeme al#2o#3-fe#2o#3-sio#2-h#2o. L'analyse quantitative de la distribution de al et fe dans les melanges naturels cryptocristallins etudies a necessite l'utilisation et le developpement de methodes et modelisations physiques: (i) affinement rietveld multiphases des diffractogrammes des rayons x sur poudre ; (ii) mise en ordre magnetique dans les oxyhydroxydes de fer (spectroscopie mossbauer du #5#7fe) ; (iii) creation d'un code de calcul pour la simulation des spectres de resonance paramagnetique des ions de transition dans les materiaux polycristallins
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Ruan, Huada. "Spectroscopic studies of nano-structures of AI and Fe phases, bauxite and their thermally activated products." Thesis, Queensland University of Technology, 2005. https://eprints.qut.edu.au/16107/1/Huada_Ruan_Thesis.pdf.
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This thesis is made as it is submitted as a sum of published papers by the candidate. Aluminium hydroxides including gibbsite, boehmite and diaspore, are the major components, while iron hydroxides/oxides and kaolinite are the major impurities in bauxite. The dehydroxylation pathways during thermal activation of bauxite have been debated for decades. Phase transformation during thermal activation or calcination of bauxite to achieve high yields of alumina has been an important goal for the refining industry. This study deals with natural and synthetic aluminium and iron hydroxides using vibrational spectroscopy in conjunction with X-ray diffraction and electron microscopy, followed by the characterisation of the phase transformation in activated bauxite. In the Raman spectra, gibbsite shows four bands at 3617, 3522, 3433 and 3364 cm-1, and bayerite shows seven bands at 3664, 3652, 3552, 3542, 3450, 3438 and 3420 cm-1 in the hydroxyl stretching region. Five bands at 3445, 3363, 3226, 3119 and 2936 cm-1 for diaspore and four at 3371, 3220, 3085 and 2989 cm-1 for boehmite are present. The far infrared spectrum of boehmite resembles that of diaspore in the 300-400 cm-1 region. Boehmite has two characteristic bands at 366 and 323 cm-1 while diaspore has five at 354, 331, 250, 199 and 158 cm-1. The far infrared spectrum of gibbsite resembles that of bayerite in the 230-300 cm-1 region. Gibbsite shows three characteristic bands at 371, 279 and 246 cm-1 whereas bayerite shows six at 383, 345, 326, 296, 252 and 62 cm-1. The far infrared spectra are in-harmony with the FT-Raman spectra, allowing the study and differentiation of the stretching of AlO4 units to characterize these four alumina phases. The surface properties of kaolinite and gibbsite are studied using Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS). The FTIR-PAS spectra of kaolinite are recorded at mirror velocities of 0.05, 0.1, and 0.2 cm s-1, and compared to the gibbsite spectra recorded at mirror velocity of 0.2 cm s-1. It is found that the hydroxyl surface spectra are a function of depth. For the FTIR spectroscopy of thermal dehydroxylation of goethite to form hematite, the intensity of hydroxyl stretching and bending vibrations decreased with the extent of dehydroxylation of goethite. Infrared absorption bands clearly show the phase transformation between goethite and hematite, in particular the migration of excess hydroxyl units from goethite to hematite. Data from the band component analysis of FT-IR spectra indicate that the hydroxyl units mainly affect the a- plane in goethite and the equivalent c- plane in hematite. A larger amount of non-stoichiometric hydroxyl unit is found to be associated with a higher aluminium substitution. A shift to a higher wavenumber of bending and hydroxyl stretching vibrations is attributed to the effects of aluminium substitution associated with non-stoichiometric hydroxyl units on the a-b plane relative to the b-c plane of goethite. The dehydroxylation pathways of both the aluminium hydroxides and the impurities are intensively studied. Gibbsite completely decomposed at 250 °C, followed by boehmite and kaolinite at 500 °C. No phase transformations were observed for hematite, anatase, rutile or quartz up to 800 °C. Small amounts of gibbsite transformed to boehmite but the majority transformed to chi (?) alumina, a disordered transition alumina phase, after dehydroxylation at 250 °C. The dehydroxylation pathways of crystalline gibbsite follow the orders: (a) gibbsite (<250 °C) to boehmite (250-450 °C) to gamma alumina (?) (500-800 °C); or (b) gibbsite (<250 °C) to chi alumina (?) (250-800 °C) to chi (?) + kappa alumina (?) (700-800 °C). Boehmite completely altered to gamma alumina (?), while kaolinite altered to metakaolinite at 500 °C. The vibrational spectroscopy including FT-IR and FT-Raman, is a rapid, accurate and non-destructive technique in characterising both single and mixed mineral phases. In particular, the vibrational spectroscopy has shown its advantages over other techniques in terms of its sensitivity to hydroxyl groups. Future work on the simulation of bauxite dehydroxylation with emphasis on the studies of transition aluminas is proposed. The application of the advanced technique synchrotron x-ray spectroscopy, in addition to those techniques used in the present study, is recommended.
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Ruan, Huada. "Spectroscopic Studies of Nano-Structures of AI and Fe Phases, Bauxite and Their Thermally Activated Products." Queensland University of Technology, 2005. http://eprints.qut.edu.au/16107/.
Full textAbstract:
This thesis is made as it is submitted as a sum of published papers by the candidate. Aluminium hydroxides including gibbsite, boehmite and diaspore, are the major components, while iron hydroxides/oxides and kaolinite are the major impurities in bauxite. The dehydroxylation pathways during thermal activation of bauxite have been debated for decades. Phase transformation during thermal activation or calcination of bauxite to achieve high yields of alumina has been an important goal for the refining industry. This study deals with natural and synthetic aluminium and iron hydroxides using vibrational spectroscopy in conjunction with X-ray diffraction and electron microscopy, followed by the characterisation of the phase transformation in activated bauxite. In the Raman spectra, gibbsite shows four bands at 3617, 3522, 3433 and 3364 cm-1, and bayerite shows seven bands at 3664, 3652, 3552, 3542, 3450, 3438 and 3420 cm-1 in the hydroxyl stretching region. Five bands at 3445, 3363, 3226, 3119 and 2936 cm-1 for diaspore and four at 3371, 3220, 3085 and 2989 cm-1 for boehmite are present. The far infrared spectrum of boehmite resembles that of diaspore in the 300-400 cm-1 region. Boehmite has two characteristic bands at 366 and 323 cm-1 while diaspore has five at 354, 331, 250, 199 and 158 cm-1. The far infrared spectrum of gibbsite resembles that of bayerite in the 230-300 cm-1 region. Gibbsite shows three characteristic bands at 371, 279 and 246 cm-1 whereas bayerite shows six at 383, 345, 326, 296, 252 and 62 cm-1. The far infrared spectra are in-harmony with the FT-Raman spectra, allowing the study and differentiation of the stretching of AlO4 units to characterize these four alumina phases. The surface properties of kaolinite and gibbsite are studied using Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS). The FTIR-PAS spectra of kaolinite are recorded at mirror velocities of 0.05, 0.1, and 0.2 cm s-1, and compared to the gibbsite spectra recorded at mirror velocity of 0.2 cm s-1. It is found that the hydroxyl surface spectra are a function of depth. For the FTIR spectroscopy of thermal dehydroxylation of goethite to form hematite, the intensity of hydroxyl stretching and bending vibrations decreased with the extent of dehydroxylation of goethite. Infrared absorption bands clearly show the phase transformation between goethite and hematite, in particular the migration of excess hydroxyl units from goethite to hematite. Data from the band component analysis of FT-IR spectra indicate that the hydroxyl units mainly affect the a- plane in goethite and the equivalent c- plane in hematite. A larger amount of non-stoichiometric hydroxyl unit is found to be associated with a higher aluminium substitution. A shift to a higher wavenumber of bending and hydroxyl stretching vibrations is attributed to the effects of aluminium substitution associated with non-stoichiometric hydroxyl units on the a-b plane relative to the b-c plane of goethite. The dehydroxylation pathways of both the aluminium hydroxides and the impurities are intensively studied. Gibbsite completely decomposed at 250 °C, followed by boehmite and kaolinite at 500 °C. No phase transformations were observed for hematite, anatase, rutile or quartz up to 800 °C. Small amounts of gibbsite transformed to boehmite but the majority transformed to chi (χ) alumina, a disordered transition alumina phase, after dehydroxylation at 250 °C. The dehydroxylation pathways of crystalline gibbsite follow the orders: (a) gibbsite (<250 °C) to boehmite (250-450 °C) to gamma alumina (γ) (500-800 °C); or (b) gibbsite (<250 °C) to chi alumina (χ) (250-800 °C) to chi (χ) + kappa alumina (κ) (700-800 °C). Boehmite completely altered to gamma alumina (γ), while kaolinite altered to metakaolinite at 500 °C. The vibrational spectroscopy including FT-IR and FT-Raman, is a rapid, accurate and non-destructive technique in characterising both single and mixed mineral phases. In particular, the vibrational spectroscopy has shown its advantages over other techniques in terms of its sensitivity to hydroxyl groups. Future work on the simulation of bauxite dehydroxylation with emphasis on the studies of transition aluminas is proposed. The application of the advanced technique synchrotron x-ray spectroscopy, in addition to those techniques used in the present study, is recommended.
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Lowe, David F. "Valuation of mineral-linked assets : a contingent claim approach in the bauxite/aluminium industry." Thesis, University of Manchester, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.504697.
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This thesis is about the interface between theoretical and empirical practice in the evaluation of mineral asset investments. It takes the Jamaican Bauxite industry as a case study for applying a real option model for estimating the value of managerial flexibility in the context of the pre and post development stages ofa mine. The thesis begins from the position that classic DCF calculations understate the value of real options embedded in the mineral industry. To evaluate these options, this thesis replicates and extends the work of Trigeorgis (1996) by applying the model and method to an actual mineral study rather than an hypothetical case. It contributes by further explaining the non-additivity of options, and it compares alternative binomial models, investigating their properties and limitations, including convergence and accuracy ofthe numerical results. The thesis also briefly compares theory with practice. ill common with studies ofother industries (Davis, 1996), we find that mining firms in the bauxite industry use classical valuation methods of evaluation such as DCF. However, recent decisions in the Jamaican bauxite industry suggest that the mining firms make decisions which are either irrational, if based on classical valuation techniques, or can be explained by the implicit inclusion of some combination of real options (as in our case study) or by unrevealed terms negotiated with the host government.
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Bellenguez, Ghislaine. "Étude minéralogique et géochimique d'une bauxite du stéphanien du bassin houiller de Decazeville (Aveyron)." Toulouse 3, 1987. http://www.theses.fr/1987TOU30246.
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Güneysu, Betil. "Les problèmes juridiques internationaux posés par l'exploitation des ressources naturelles : l'exemple de la bauxite." Université Robert Schuman (Strasbourg) (1971-2008), 1994. http://www.theses.fr/1994STR30006.
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La bauxite et l'alumine représentent des ressources vitales pour les économies en développement. La mise en valeur des réserves se fait par l'intermédiaire des entreprises multinationales. La position de l'industrie au centre de complexe militaro-industriel, les conditions de l'approvisionnement, son contrôle de processus de la mise en valeur sur le plan mondial ont permis aux entreprises de dominer leurs relations avec les gouvernements. Le droit international ne doit pas être un détour permettant de généraliser la privatisation du pouvoir économique. L'affirmation du primat de développement semble fournir l'explication de l'inaliénabilité de la souveraineté sur les ressources naturelles. L'internationalisation doit avoir pour but la publicisation du contrat de développement, la soumission du contrat au droit international par attraction de la personnalité de l'état, défenseur de l'intérêt national doté de prérogatives de souverainetéBauxite and alumina are vital resources for underdeveloped economies. Bauxite is exploited by multinational entreprises. The position of the aluminium industry in the military complex, its contrat of the processus of exploitation of the mineral permitted multinational entreprises to dominate their relations with the governments. Inalienability of the souvereignty on natural resources confers to state contracts a public character. In no system of law are private interests permitted to prevail over duly established public interest making impossible actions required for public good
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Williams, Richard James. "Karst-associated bauxite deposits of Parnassos-Ghiona, Central Greece : ore genesis and structural evolution." Thesis, University of Brighton, 2014. https://research.brighton.ac.uk/en/studentTheses/2b04d019-0696-4544-a13d-b2de8971a69b.
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The karst-associated bauxites of the Parnassos-Ghiona zone in Central Greece are part of the large Mesozoic age Mediterranean Karst Bauxite belt. Greece is responsible for around 50% of European bauxite production, and has an estimated 600 million tonnes of bauxite reserves. This investigation focuses on the bauxites of Mount Iti and Mount Ghiona, two mountains in the west of the Parnassos-Ghiona zone that are currently being explored and mined by Greek bauxite producer, Elmin S.A. The aim was to develop a better geological understanding of the ore genetic history and regional structural evolution to aid ore deposit science and bauxite exploration. Within the Parnassos-Ghiona zone the bauxites were deposited as three separate ore horizons intercalated with thick limestone layers during the early Jurassic, late Jurassic and late Cretaceous. Only the upper two bauxite horizons are economic and therefore formed the focus of this investigation.
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Senaputra, Alexander. "The impact of desilication products on the flocculation and sedimentation properties of bauxite residue." Thesis, Curtin University, 2014. http://hdl.handle.net/20.500.11937/1522.
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In the Bayer processing of bauxite, dissolved silica re-precipitates as aluminosilicates or desilication products (DSPs) that adversely affect residue separation by flocculation and thickening prior to product precipitation. DSP was shown to form at the surface of hematite, impacting upon the extent, efficiency and mechanism of aggregation with a number of different polymer reagents. Real-time measurement of aggregate properties provided new insights on fines capture. The practical implications for full-scale feedwell flocculation were explored.
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SOUZA, WANDER B. de. "Estudo da adição de lama de bauxita em polímero de poli(metacrilato de metila) por meio de polimerizaçao em massa e moldagem em casting." reponame:Repositório Institucional do IPEN, 2008. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11717.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Garcia, Marta Cristina Suarez. "Modificação do resíduo de bauxita gerado no processo Bayer por tratamento térmico." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-13062013-121328/.
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A lama vermelha é o resíduo gerado pela Indústria do Alumínio. Assim como outros resíduos industriais apresenta características complexas com inúmeras dificuldades de manipulação, além de ser um material perigoso pela sua baixa granulometria e alcalinidade. É um resíduo com potencial poluidor alto, agravado pela forma de disposição vulnerável geralmente adotada, sendo esta a disposição do resíduo em lagoas projetadas para esta finalidade. O estudo e desenvolvimento de alternativas sustentáveis para a utilização da lama vermelha devidamente tratada como matérias-primas de outros processos são tendências importantes e necessárias no contexto mundial de preservação do meio ambiente. O objetivo deste estudo é compreender o comportamento da lama vermelha sob a influência de diferentes temperaturas de tratamento térmico. Baseados nos efeitos de redução de área e transformações de fases, característicos dos processos térmicos, adotou-se um foco de análise voltado para a redução pH e dos íons livres. A identificação dos pHs adequados de análise da concentração de íons solúveis foi feita com base nas curvas de mobilidade eletroforética e condutividade. Os resultados obtidos para as amostras calcinadas mostraram queda do pH inicial das dispersões e da concentração dos íons solubilizados. Esse efeito pode ser atribuído a redução de área e a incorporação de íons à estrutura, o que assegura ao resíduo menor reatividade.Red mud is the waste generated by Aluminium Industry, like other industrial wastes, has complex features with several difficulties in handling, as well as being a hazardous material because of its low particle size, alkalinity and high amount generated. It is a waste with high pollution potential, compounded by the vulnerability of the disposition generally adopted, usually in lagoons designed for this purpose. The study and development of sustainable alternatives for the use of properly treated red mud, as raw material of other processes, are important tendencies and necessaries in the global context of environmental preservation. However, this work deals the thermal treatment as method to modify the characteristics of the waste, suggesting the reduction of alkalinity with the lower leaching of alkaline ions. This approach can be a discarding alternative most reliable and safe for the environment. The objective of this study is understand the red muds behavior using thermal treatment. Based on the reduction effects of the area and phase transformations characteristic of thermal process, the analysis was taken observing the reduction of free ions and pH. Identification of correct pH of analyse of soluble ions concentration was based at mobility electrophoretic and conductivity graphics. The results of calcined samples showed reduction of initial pH and the concentration of soluble ions. This effect could be assigned to the area reduction and ions incorporation at structure, which ensures the residue lower reactivity.
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Moreira, Edwiges Andrea Santos. "Comportamento de uma área de resíduos de bauxita durante a operação de enchimento." Universidade do Estado do Rio de Janeiro, 2015. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=9393.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorA técnica de deposição de resíduos de processamento de bauxita prevê uma operação inicial de lançamento de resíduos, por via úmida, no interior de reservatórios artificiais. Nesta fase de deposição, os resíduos são lançados em forma de polpa, sofrendo processos de sedimentação e adensamento por peso próprio. A vida útil dos reservatórios depende fundamentalmente do comportamento geotécnico do resíduo, cujas propriedades variam ao longo do tempo e da profundidade. A presente dissertação tem como objetivo a análise do comportamento de uma área de resíduos de bauxita durante a operação de enchimento do reservatório. Para tanto, foi utilizado o programa Plaxis, que executa análises tensão-deformação pelo método dos elementos finitos. Os parâmetros geotécnicos do resíduo foram definidos com base em ensaios de adensamento e piezocone, executados em amostras representativas da polpa de resíduos. Para calibração do modelo, a batimetria executada no reservatório foi confrontada com as cotas de enchimento previstas numericamente. Finalmente, a distribuição dos parâmetros geotécnicos (peso específico, índice de vazios, permeabilidade) com a profundidade prevista numericamente foi confrontada com os valores medidos no campo, ao final da etapa de enchimento. O conhecimento da variação dos parâmetros geotécnicos com a profundidade ao final do enchimento é importante para avaliar o comportamento do reservatório na etapa de operação de alteamento, e para a estimativa do ganho de vida útil do reservatório. Os resultados permitiram avaliar o funcionamento da drenagem de fundo, a distribuição complexa dos excessos de poropressão ao final do enchimento, os perfis dos índices físicos com a profundidade e o ganho de vida útil. As análises mostraram que o programa foi capaz de reproduzir os processos simultâneos de sedimentação e adensamento por peso próprio, em análises de enchimento de reservatórios de resíduos.
The technique of disposing of waste bauxite processing provides an initial launch of operation, the wet disposal, within artificial reservoirs. In this phase of deposition, the waste is released in the form of pulp, suffering processes of sedimentation and consolidation by self-weight. The useful life of the reservoirs depends crucially on the Geotechnical behavior of the residue, whose properties vary over time and depth. The present dissertation aims to behavior analysis of a bauxite waste area during the operation of filling the tank. To this end, we used the program Plaxis, which performs stress-strain analyses by the finite element method. The Geotechnical parameters of residue were defined based on piezocone, consolidation and tests carried out on representative samples of waste pulp. For calibration of the bathymetry model executed in the reservoir was faced with filling quotas provided for numerically. Finally, the distribution of geotechnical parameters (specific weight, void ratio, permeability) with the depth expected numerically was confronted with the values measured in the field, at the end of the filling stage. Knowledge of geotechnical parameters variation with depth at the end of the filling is important to evaluate the behavior of the reservoir in heightening operation step, and for the estimation of the useful life of the reservoir. The results made it possible to assess the functioning of the Fund drainage, the complex distribution of excess pore pressure dissipations at the end of the filling, the profiles of physical indexes with the depth and the gain of life. The analysis showed that the program was able to reproduce the simultaneous processes of sedimentation and consolidation by selfweight, in analyses of reservoir filling of waste.
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Scott, Michael Emanuel. "The politics of radical nationalism in Guyana : the case of nationalization of bauxite and sugar." Thesis, Goldsmiths College (University of London), 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283520.
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Knierzinger, Johannes. "Le contrôle des multinationales sur les villes de bauxite en Guinée : comment descendre d'un lion." Thesis, Paris 1, 2015. http://www.theses.fr/2015PA010657.
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Ce travail de thèse est consacré aux conséquences sociales et politiques de l’exploitation minière de la bauxite en Guinée. Quelques années avant son indépendance en octobre 1958, la Guinée est devenue membre d’un réseau mondial de production incluant mines, raffineries, fonderies et usines, métallurgiques, toutes contrôlées par un petit nombre de sociétés multinationales interconnectées. Ce travail de recherche se penche sur les conséquences politiques et sociales de ce processus d’intégration dans une filière globales aboutissant à la production de voitures, de boîtes de conserve, d’avions, de bâtiments ou d’autres produits en aluminium. Au-delà du contrôle extérieur existant de fait sur les différentes villes productrices de bauxite, les trois mines de bauxite de Guinée ont également été la source des principales recettes depuis l’indépendance et ont de ce fait un impact décisif sur l’histoire du pays. Afin de mettre en évidence ces interconnections et rapports de force, la thèse interroge (1) les intérêts des pays producteurs et importateurs ainsi que des institutions internationales en jeu (2) les formes de gestion des risques et les stratégies de maximisation du profit (chain governance) des multinationales et (3) les formes de renégociation et les effets de ce réseau mondial de production au niveau localThis is a thesis on the social and political consequences of bauxite mining in Guinea . A few years before independance in October 1958, Guinea became part of a worldwide production network of mines, refineries, smelters and metal-working factories which where all controlled by a few interconnected companies. The thesis focuses on the political and social consequences of this inclusion into global commodity chain which results in cars, cans, airplanes, building and other things made out of aluminium. Beside the de facto foreign control over several bauxite towns, the three Guinean bauxite mines also provided also most governmental income since independance and had thereby a strong impact on the history of this country. In order to show these interconnections the thesis treats (1) the intrests of producer countries, receiver countries and international institutions (2) risk management and profit maximizing strategies (chain governance) of transnational companies and (3)the renogatiation and the effects of this global production network on the local level