Tesis: "Exploitation de la bauxite"

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Diaw, Mody. "De Boké à Gardanne, l’expérience des travailleurs de la bauxite au prisme de la justice environnementale". Electronic Thesis or Diss., Bordeaux, 2024. http://www.theses.fr/2024BORD0265.

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Depuis plusieurs années, la question des rejets liquides et solides issus de l’extraction de l’alumine de la bauxite par l’usine d’Alteo Gardanne (France) est devenu un problème public grâce à la mobilisation d’associations environnementales, de collectifs d’usagers des Calanques et de riverains de l’usine et du site de stockage des déchets solides, qui dénoncent les impacts sur l’environnement et la santé des habitants. La manière dont le problème est défini par ces mobilisations lui confère une dimension locale (Deldrève et Metin, 20191), alors que, depuis l’épuisement des mines de bauxite de Provence, l’usine d’alumine Alteo (appartenant antérieurement à Pechiney puis Rio Tinto), continue sa production en s’approvisionnant en bauxite auprès de la Compagnie des Bauxites de Guinée (CBG), qui exploite les gisements de la région de Boké où les communautés riveraines des mines dénoncent aussi les conséquences socio-environnementales et sanitaires de la politique nationale d’extraction de la bauxite2. Ainsi, la trajectoire de la bauxite confère au problème, une dimension internationale et générique. En outre, alors que de la Guinée à Gardanne, les enjeux environnementaux et sanitaires pour les communautés riveraines des sites d’exploitation et de transformation ou encore des voies de transport de la bauxite sont largement publicisés, ceux liés à la santé et aux conditions de travail des ouvriers qui extraient, transportent et transforment la bauxite restent invisibilisés. Les études en épidémiologie qui se sont intéressées à la situation des travailleurs de la bauxite portent généralement sur les mesures de leur exposition aux rayons gamma et aux niveaux de concentration des composantes des poussières inhalées dans les mines et dans les raffineries (Brian et al., 20123 ; Dennekamp et al., 20154). Les conclusions de ces études sur l’exposition au risque des ouvriers ont donné lieu à des controverses et leurs approches consistant à mesurer des moyennes et non des expositions réelles sont largement critiquées (G. Hecht, 20125), du fait qu’elles ne permettent pas de prendre en compte les différences d’exposition liées aux différentes situations de travail. Aussi, cette thèse en sociologie qui, s’inscrit dans un projet de recherche pluridisciplinaire en sciences sociales (Justbaux)6, a pour objectif de comprendre le rapport des ouvriers à la bauxite et leur expérience du travail et des risques. Qui sont les travailleurs sur la trajectoire de la bauxite ? Quels sont les enjeux de justice et inégalités environnementales qui se donnent à lire dans leur rapport à la bauxite ? Quelles sont leurs positions face aux mobilisations des riverains (dont ils font parfois partie) et des écologistes ? Comment qualifient-ils la matière et définissent-ils les problèmes liés à son exploitation ? Je fais l’hypothèse que le rapport à la bauxite et l’expérience des risques liés à son extraction, sa transformation et son transport, sont non seulement fonction des situations de travail, des techniques employées et réglementations appliquées, mais aussi du statut des ouvriers, de leur précarité et dépendance à la compagnie qui les emploie. Pour vérifier cette hypothèse, je mobilise un cadre d’analyse qui emprunte ses concepts à la sociologie du travail et à la justice environnementale. Ma démarche est qualitative. Elle comprend des entretiens semi-directifs avec des ouvriers situés à différentes étapes de la trajectoire de la bauxite ainsi que des observations de leurs situations de travail et activités. Cette ethnographie du travail dans les mines en Guinée, aux côtés des transporteurs, au sein de l’usine de pré-transformation de la bauxite à Kamsar ou encore de l’usine de production d’alumine à Gardanne, sera conjuguée à un travail d’archives et de documentation
For several years now, the issue of liquid and solid discharges from the extraction of alumina from bauxite by the Alteo Gardanne plant (France) has been a public issue, thanks to the mobilization of environmental associations, user groups in the Calanques and local residents of the plant and the solid waste storage site, who denounce the impacts on the environment and the health of local residents. The way in which the problem is defined by these mobilizations gives it a local dimension (Deldrève and Metin, 2019, while, since the depletion of Provence’s bauxite mines, the Alteo alumina plant (previously owned by Pechiney and then Rio Tinto), continues its production by sourcing bauxite from Compagnie des Bauxites de Guinée (CBG), which mines deposits in the Boké region, where communities living near the mines are also denouncing the socio-environmental and health consequences of the national bauxite mining policy. Thus, the trajectory of bauxite gives the problem an international and generic dimension. What’s more, while environmental and health issues for communities living close to bauxite mining and processing sites or transport routes are widely publicized from Guinea to Gardanne, those relating to the health and working conditions of the workers who extract, transport and process bauxite remain invisible. Epidemiological studies that have addressed the situation of bauxite workers generally focus on measurements of their exposure to gamma radiation and concentration levels of inhaled dust components in mines and refineries (Brian et al., 2012; Dennekamp et al., 2015). The conclusions of these studies on workers’ exposure to risk have given rise to controversy, and their approaches of measuring averages rather than actual exposures have been widely criticized (G. Hecht, 2012), on the grounds that they fail to take into account differences in exposure linked to different work situations. The aim of this sociology thesis, which is part of a multidisciplinary social science research project (Justbaux), is to understand workers’ relationship with bauxite and their experience of work and risks. Who are the workers on the bauxite trajectory? What issues of environmental justice and inequality are at stake in their relationship with bauxite? What are their positions with regard to the mobilization of local residents (of which they are sometimes a part) and environmentalists? How do they describe the material and define the problems associated with its use? I hypothesize that people’s relationship with bauxite and their experience of the risks associated with its extraction, processing and transport are a function not only of their work situation, the techniques employed and the regulations applied, but also of the status of the workers, their precariousness and their dependence on the company that employs them. To test this hypothesis, I use an analytical framework that borrows concepts from the sociology of work and environmental justice. My approach is qualitative. It includes semi-structured interviews with workers at different stages of the bauxite trajectory, as well as observations of their work situations and activities. This ethnography of work in the mines in Guinea, alongside the transporters, at the bauxite pre-processing plant in Kamsar and at the alumina production plant in Gardanne, will be combined with archive and documentation work

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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 vibrations
The 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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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 &amp 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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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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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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16

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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17

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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18

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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19

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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20

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 TECNOLÓGICO
Este 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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21

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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22

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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23

Storer, Andrew John. "Host exploitation in Scolytidae". Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335804.

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24

Alderman, James. "Exploitation of flow control". Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.506602.

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25

Eyabi, Frankline Beching. "Protection of excessive exploitation". Thesis, Видавництво СумДУ, 2011. http://essuir.sumdu.edu.ua/handle/123456789/9987.

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26

Danielsson, Lina y 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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27

Jeoung, Jaehyun. "Exploitation minière et exploitation humaine : les charbonnages dans le Vietnam colonial, 1874-1945". Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCC053/document.

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Le charbon était connu au Vietnam depuis longtemps, mais c’est pendant la période coloniale qu’il fit l’objet d’une exploitation systématique. Les Français s’intéressèrent à ces ressources minières du Vietnam dès avant la conquête coloniale. Après l’établissement du protectorat français au Tonkin et en Annam en 1883-1884, l’exploitation des mines de charbon connut un essor rapide sous l’effet de l’afflux de capitaux et l’introduction de techniques de France et devint l’une des principales activités industrielles du Tonkin. Les autorités coloniales soutinrent fortement la « mise en valeur » de la colonie par le capitalisme français. Néanmoins, il n’était pas toujours facile même pour les plus grandes compagnies françaises d’organiser une nouvelle activité de production dans un pays peu industrialisé Alors que les charbonnages de Hòn Gai parvinrent à surmonter des difficultés d’ordre financier, commercial et industriel et réaliser des profits considérables, la plupart des autres entreprises minières ne rémunèrent jamais suffisamment les capitaux engagés, et même certaines d’entre elles se terminèrent par des échecs complets. En particulier, les compagnies minières rencontrèrent une grande difficulté à recruter des ouvriers et les retenir dans les mines, dont les conditions de travail furent particulièrement dures. La forte mobilité caractérisait la main-d’œuvre des mines et retarda ainsi la formation d’une conscience de classe parmi les ouvriers des mines. La grève générale des ouvriers de Hòn Gai en novembre 1936 témoigne pourtant la naissance d’une nouvelle classe sociale, que les militants communistes vietnamiens visèrent à transformer en avant-garde révolutionnaire contre le colonialisme et le capitalisme
Coal was known in Vietnam from early on, but it was during the colonial period that it was subjected to systematic exploitation. The French were interested in these mineral resources of Vietnam before the colonial conquest. After the establishment of French protectorate in Tonkin and in Annam in 1883-1884, coal mining grew quickly as a result of influx of capital and introduction of technics from France and became one of principal industrial activities in Tonkin. The colonial authorities strongly supported the “mise en valeur” of colony by French capitalism. Nevertheless, it was not easy even for the biggest French companies to organise a new production activity in a country hardly industrialised. Whereas Hòn Gai colliery succeeded in overcoming financial, commercial and industrial difficulties and to make sizeable profits, most other mining enterprises did never provide enough returns to capital employed and even some of them ended in total failure. In particular, mining companies had great difficulty in recruiting workers and retaining them to mines, working conditions of which were particularly harsh. High mobility characterised workforce of mines and delayed thus formation of class consciousness among mine workers. The general strike of Hòn Gai workers in november 1936 witnessed however emergence of a new social class, whom Vietnamese communist activists sought to make revolutionary vanguard against colonialism and capitalism

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28

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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29

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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30

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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31

van, der Neut Wendy. "Consensual exploitation : the moral wrong in exploitation and legal restrictions on consensual exploitative transactions". Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/9594.

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This thesis is about so-‐called consensual exploitative transactions: transactions to which all parties agree voluntarily, and which are beneficial for all parties, but which are still widely considered exploitative, and for that reason legally restricted in many countries. The thesis asks two main questions: 1. What is wrong with consensual exploitation? 2.What implications does the answer to this question have for the legal restriction of consensual transactions that are regarded exploitative in modern liberal societies? In answer to the first research question, the thesis starts by distinguishing and analysing five competing views of the wrong in consensual exploitation that exist in the present-‐day philosophical debate on exploitation; and rejects all five answers. Next, the thesis offers an alternative answer, which is that the wrong in consensual exploitation can best be understood as a matter of greediness—a failure of the virtue of generosity. The thesis then turns to the second research question: what understanding exploitation as greediness implies for the legal restriction of exploitative transactions. It discusses and rejects the view that law ought only to be used to regulate ‘right’ and ‘wrong’ behaviour, and not to promote virtues or discourage vices, such as generosity and greediness. The thesis argues that legal restrictions on consensual exploitative transactions can be justified as a means to prevent greediness, and to promote a certain other-‐regardingness, and illustrates this argument with two examples of laws that regulate consensual transactions which are widely regarded exploitative: minimum wage laws and payday loan laws.

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32

Stockhammer, Engelbert y Paul Ramskogler. "Uncertainty and exploitation in history". Inst. für Volkswirtschaftstheorie und -politik, WU Vienna University of Economics and Business, 2007. http://epub.wu.ac.at/82/1/document.pdf.

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The paper builds on the Marxist concept of exploitation to explore the meaning of the Post Keynesian notion of uncertainty. Uncertainty is mediated by institutions and is distributed unevenly among different social groups. As different historical social formations entail different institutional structures, the distribution and nature of uncertainty also differ. The configurations between class relations and uncertainty are analyzed for the capitalist, feudal and slave modes of production. It is demonstrated that modes of production do not only imply specific exploitative relations but also different relative distributions of uncertainty amongst classes. Joining Marxian and Post Keynesian approaches allows a richer understanding of exploitive relations and illuminates the full societal impact of uncertainty. It is shown that only in capitalism is the exploited class exposed to a substantial degree of economic uncertainty. (author's abstract)
Series: Department of Economics Working Paper Series

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33

Denham, Sean Dexter. "Animal exploitation in medieval Ireland". Thesis, Queen's University Belfast, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492149.

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Two proxies are best suited to an investigation of animal exploitation in medieval Ireland, the historical record and the zooarchaeological record. Extensive analyses of both have been brought together here to address this topic. In selecting period documents to include in the study, an attempt was made t.o cover the various historical traditions seen in medieval Ireland; this includes Irish annals, Anglo-Norman administratixe documents, and narrative histories and observations from medieval writers. One of the more important aspects of this thesis was the accumulation of as authoritative corpus of zooarchaeological data as possible. Towards these ends, a large number ofpublished and unpublished reports have been brought together to form a complete picture ofthe state of the medieval Irish faunal record. Three new faunal assemblages, from Carrickmines Castle, Co. Dublin, Dunboyne Castle, Co. Meath, and Ballybarrack souterrain, Co. Louth, have also been analysed and included in the thesis. On a broader scale, this thesis highlights three problems in both the archaeology of medieval Ireland. The first of these is the integration of historical and archaeological data, and to what extent it is appropriate to do so. The second is a general problem within archaeology and that is the treatment of specialist reports. Too often such reports are either not fully published or not published at all, limiting or eliminating the usefulness of the data they contain. Alternatively, they are not readily accessible to researchers whom they would benefit. Finally, the state of the medieval Irish archaeological record is heavily biased towards Anglo-Norman/urban sites. This is of special significance in that, due to a lake of economic records, zooarchaeology is one ofthe few strands of evidence available which may shed light on animal exploitation in Gaelic Ireland. Supplied by The British Library - 'The world's knowledge'

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34

Todde, Carlo. "Exploitation asymétrique d'un corridor THT". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0009/MQ38713.pdf.

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35

Arvizo, Adrian E. Janowiak Vincent J. "Field level computer exploitation package". Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion.exe/07Mar%5FArvizo.pdf.

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36

Bubeck, Diemut. "Women's work and women's exploitation". Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385463.

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Fogarty, Elizabeth Mary Rose. "The scientific exploitation of SWIFT". Thesis, University of Oxford, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.555372.

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The SWIFT integral field spectrograph is an adaptive optics assisted I and z-band IFS designed an built by a dedicated instrument team at the University of Oxford. In this thesis I describe my contribution to the construction, commissioning and characterisation of SWIFT as part of the SWIFT team. I also describe two observational projects subsequently undertaken with SWIFT. Firstly a kine- matic study of the ring galaxy Arp 147. This is a typical ring galaxy and companion system, thought to have been created during a collision between the companion galaxy and a normal disk which was subsequently disrupted to form the ring shape seen today. SWIFT was used to obtain spatially resolved kinematics over the ring galaxy thereby probing the conditions under which the collision occurred. Integrated spectra are also used to establish some physical properties associated with the system, leading to a robust understanding of the timescales involved in the interaction. Next SWIFT was used to observe a small sample of redshift desert (z ~ 1) galaxies. These objects were chosen from the DEEP2 sample in order to probe a range of different dominant kinematics, that is galaxies which are rotation-dominated, galaxies which are velocity dispersion- dominated and some objects displaying a mixture between the two. Here I analyse two objects from this sample. The Eagle galaxy is a turbulent and highly star-forming galaxy at a redshift of z = 0.7686. The Eagle exhibits a morphology and uneven kinematics indicating a possible major merger. The Diamond Ring galaxy is a galaxy at a redshift of z = 1.1592. The Diamond Ring also displays disrupted kinematics, with a knotty morphology. It has a typical star formation rate for its mass.

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38

Janowiak, Vincent J. "Field level computer exploitation package". Thesis, Monterey, California. Naval Postgraduate School, 2007. http://hdl.handle.net/10945/3635.

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On today's battlefield whether in Afghanistan or Iraq, ground combat forces are dealing with an adversary that has embraced the use of computers and electronic devices. Until now, there was no package of consolidated forensic tools available to the ground combat forces with the capability of conducting a quick interrogation of these devices. After a unit has captured a target that possesses electronic devices that require immediate exploitation, the devices are transferred to higher authority. Valuable time is lost locating and capturing associates of the target as the information is sent away to higher authority for analysis. The product of this thesis, Interrogator, was designed to prevent or reduce the time lost by allowing anyone to quickly retrieve data that is stored on a computer. This capability will positively aid a small unit commander's ability to exploit critical vulnerabilities of the enemy in a timely manner and improve the survivability of the unit and the ability to complete their mission.

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39

Mulkeen, Nicola. "Socially constructed luck and exploitation". Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/socially-constructed-luck-and-exploitation(aef17fb4-2236-4026-bb7a-6b4a689bb4d2).html.

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This thesis shows that exploitation can arise from a just background, via just steps, when we exercise our moral rights. The theory rests on the idea that exploitation can arise via a special category of luck, which I call socially constructed luck. By taking into account what John Rawls calls background justice and what G.A. Cohen refers to as an accumulation problem, I argue that socially constructed luck is brought about through a cumulative process of people freely exercising their moral rights in the pursuit of their own conception of the good life. Unless the negative effects of this type of luck are offset, exploitative interactions can arise where people have no reasonable alternative but to enter a particular transaction. Socially constructed luck can play a direct role in privileging some individuals at the expense of others and allows for the extraction of surplus benefits. Importantly, by showing that luck egalitarianism should be understood within a conception of exploitation, the thesis not only provides a deeper understanding of how the luck egalitarian and relational egalitarian views align, but also justifies the introduction of a basic right to a reasonable alternative.

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40

Martin, Adrian Peter. "Exploitation of microchannel plate optics". Thesis, University of Leicester, 2000. http://hdl.handle.net/2381/30635.

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This thesis contains work on microchannel plate (MCP) optics as used for X-ray focusing, and can be split into two sections; research and applications.;Research into improving the reflectivity of MCPs is presented which includes results obtained at the Daresbury Synchrotron, and electron microscope analysis. Different treatments performed on Nova Scientific channel plates were shown only to make a improvement to reflectivity in the case of annealing. Evidence for a 300A layer of silica on the surfaces of the microchannels, a result of the acid etching process, was discovered.;The method of bending, or slumping MCPs to a spherical form by Photonis and Nova has been assessed, and X-ray images using slumped plates are presented. The accuracy and reproducibility of the process was not found to be excellent (within 10% of the target radius), but were acceptable for the plates slumped to date.;A comprehensive report is given of the application of channel plates as the imaging device in an Imaging X-ray Fluorescence Spectrometer, firstly at the Rutherford Appleton Laboratory and subsequently in the laboratory in Leicester. The spectrometer successfully imaged a multi-element target, resolving both elementally (down to Fluorine, Z=9) and spatially (to under 2mm) in a 34 hour integration. The concept of Bragg reflection imaging is examined as another use of the spectrometer.

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41

Pieterse, H. (Heloise). "Mutualism : the antidote to exploitation". Diss., University of Pretoria, 2018. http://hdl.handle.net/2263/63666.

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The Johannesburg, Cottesloe, Gas Works is located within the Witwatersrand zone of integration, between the University of Johannesburg and Witwatersrand. According to the Johannesburg Metropolitan Open Space System (JMOSS), there is a high priority to link secondary open spaces such as the educational premises. The Johannesburg Gas Works forms part of Jozi’s cityscape and the three remaining 45meter high gas cylinders represents a visual iconic landmark in the city. The site is currently inaccessible. The aim of this dissertation will be to determine the manner in which a user experience can be created as a palimpsest of meaning between the tangible and intangible elements on site. This implies a dialogue between the polluted areas of industrial waste, the layers of historical significance and the remnants of nature. The dissertation specifically focuses on awareness creation through the landscape experience on a post-industrial site of the associated social exploitation and environmental contamination. The Open Narrative approach will be used as part of the methodology which implies multiple interpretations by users and recognizes the presence of embedded narratives inscribed by past and future cultural practices and natural processes. A new narrative is inscribed onto the site and provides multiple experiences with each visit to the site through a phased intervention that opens up areas and processes for experience as they become decontaminated. To facilitate the palimpsest of tangible and intangible meaning, the user experience is proposed to consist of three realities: a lower, in-between and upper reality with increasing elements of transience. The essence of the design and its programme becomes mutualistic (as opposed to exploitative), based on the principles outlined by Klein (2014) namely, “interdependence, reciprocity and cooperation”. The goal of the design intervention is to foster a renewed community identity and social and environmental health through the range of active and passive activities proposed but also through the particular experiences that open up the site for renewed interpretation to all users. The dissertation demonstrates that new meanings can be applied to spaces that once posed a cultural limitation. A mutualistic relationship between the site and the people can and should co-exist.
Mini Dissertation ML(Prof)--University of Pretoria, 2018.
Architecture
ML(Prof)
Unrestricted

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42

Garnaud, Eve. "Dépendances fonctionnelles : extraction et exploitation". Phd thesis, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-00951619.

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Les dépendances fonctionnelles fournissent une information sémantique sur les données d'une table en mettant en lumière les liens de corrélation qui les unient. Dans cette thèse, nous traitons du problème de l'extraction de ces dépendances en proposant un contexte unifié permettant la découverte de n'importe quel type de dépendances fonctionnelles (dépendances de clé, dépendances fonctionnelles conditionnelles, que la validité soit complète ou approximative). Notre algorithme, ParaCoDe, s'exécute en parallèle sur les candidats, réduisant ainsi le temps global de calcul. De ce fait, il est très compétitif vis-à-vis des approches séquentielles connues à ce jour. Les dépendances satisfaites sur une table nous servent à résoudre le problème de la matérialisation partielle du cube de données. Nous présentons une caractérisation de la solution optimale dans laquelle le coût de chaque requête est borné par un seuil de performance fixé préalablement et dont la taille est minimale. Cette spécification de la solution donne un cadre unique pour décrire et donc comparer formellement les techniques de résumé de cubes de données.

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43

Eilts, J. Alexander. "The Physiology of Exploitation Competition". Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/195710.

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Water is a critical resource for which plants compete in many terrestrial communities. In arid communities where water most limits plant growth, rainfall events occur in discrete, pulsed events. These pulses of water create highly variable soil moisture availabilities. Plant species respond differently to variation in soil water availabilities throughout a season and between years. How species vary in their responses to a range of water availabilities is thought to influence community and ecosystem properties. Many previously proposed hypotheses are not suitable to explain rapidly fluctuating resource availabilities or numerous input events throughout the growing season. This dissertation uses variation in water availability as a model resource to examine how species characteristics influence the process of exploitation competition within plant communities.Experiments were conducted to examine variation in growing season, exploitation competition between several pairs of co-occurring species in the Sonoran desert. Three separate studies evaluated several components of community dynamics thought to be influenced by exploitation competition. Spatial attributes of exploitation competition were assessed by measuring the performance of a deep-rooted species across the boundary of a natural expansion of a shallowly rooted species. Then, neighborhood composition was varied for species of similar growth-form to address the affects of species characteristics to shifts in abundances under field conditions. Lastly, species from the neighborhood composition study were placed under controlled, manipulated water availabilities to measure their fundamental operational conditions.Performances of plant species in all experiments were assessed using a combination of physiological and vegetative measurements, capturing the responses of the plants to both the dynamic growth conditions during the growing season, and integrated measures of plant performance post growth season. A shared preference was found for all species, where the performance of all species was greatest when water was most available in the soil profile. This work suggests the mechanism within a functional type by which plants coexist at various abundances is in part due to the variation in responses to temporal resource gradients. The variation in availability of resources and the species composition within the community should be considered in studies of competition between plant species.

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44

Gangl, Doris. "Biotechnological exploitation of Chlamydomonas reinhardtii". Thesis, University of Kent, 2016. https://kar.kent.ac.uk/56648/.

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Microalgae have become increasingly important in the biotech sector and are currently exploited for their natural products. In recent years efforts have also been directed towards establishing them as production platforms for recombinant proteins. The aim of this thesis is to investigate the feasibility of Chlamydomonas reinhardtii as a production platform for highvalue products expressed in the chloroplast of the alga. A cytochrome P450 was introduced into the chloroplast of C. reinhardtii as a proof-of-concept study. The model enzyme CYP79A1 was successfully targeted into the chloroplast membranes and was found to be active. A bifunctional diterpene synthase, TPS4, was also expressed in the chloroplast of C. reinhardtii. TPS4 could be purified to homogeneity and is the largest enzyme expressed in the chloroplast to date. The two transgenic strains expressing CYP79A1 and TPS4 were investigated for their ability to withstand industrial growth conditions. The cell wall deficient strains were successfully cultivated in 100 L photobioreactors using a mixotrophic growth regime. They reached dry weights of 0.3 g/L and the expression of CYP79A1 and TPS4 was detected over the entire growth period. Taken together these data suggest that C. reinhardtii could be an attractive platform for recombinant protein production. Two enzymes with biotechnological relevance were expressed in the chloroplast of the alga and the transgenic cell wall deficient strains were successfully cultivated on a semi-industrial scale.

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45

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-Arellano
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
Made available in DSpace on 2018-08-24T21:24:42Z (GMT). No. of bitstreams: 1 Richter_Willian_M.pdf: 5201143 bytes, checksum: 5a032b0c7ff61300137eb551c7dc1a60 (MD5) Previous issue date: 2014
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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46

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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47

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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48

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/.

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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 (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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49

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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50

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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Tesis sobre el tema "Exploitation de la bauxite"

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