Orientador : Geraldo de Freitas Maciel. / Banca: Podalyro Amaral de Souza / Banca: Adriano Souza / Resumo: Em função da concentração de material sólido, misturas resultantes de argila e água conferem, via de regra, propriedades não-Newtonianas. Essa concentração passa a variar com a granulometria e a composição do mineral do sedimento, bem como com a qualidade da água. Algumas tentativas foram feitas na busca de melhor explicar a reologia e a dinâmica global dessas misturas nessa última década, notadamente no contexto de lavas torrenciais e misturas hiperconcentradas. Essa dissertação de mestrado tem por objetivo desenvolver uma caracterização reológica de misturas sólido-líquido (água+argila caulinítica e água+areia fina+argila caulinítica) com diferentes concentrações em volume (Cv) para as quais são determinadas, a partir de ensaios de reometria de precisão, as propriedades tais como a viscosidade aparente, tensão crítica de cisalhamento e curva de tensão de cisalhamento x taxa de deformação. Verificou-se, em condições controladas, a influência da temperatura, pH e concentração em volume (Cv) sobre a curva reológica dessas misturas, além de eventuais fenômenos de tixotropia e modo de preparo. O modelo reológico melhor ajustado para as argilas foi o de Herschel-Bulkley ( ( )n τ =τ c + k γ& ), onde: τ é a tensão de cisalhamento; τc é a tensão crítica (ou rigidez inicial); k é um termo de consistência (viscosidade aparente); n é o índice de escoamento; e dy γ& = du é a taxa de deformação. Obtém-se também, a partir de uma análise quantitativa global, leis de evolução dos diversos parâmetros reológicos em função da concentração em volume. Após a etapa de caracterização física e reológica das misturas, realizaram-se, sob condições controladas, ensaios dinâmicos através de escoamentos de lamas em canal inclinado. Nesses ensaios foram medidos os parâmetros lâmina normal, vazões... (Resumo completo, clicar acesso eletrônico abaixo). / According to solid concentration material, clay-water mixture can exhibit non- Newtonian properties. Mixture concentrations vary with the grain size distribution and the composition of the mineral sediment, as well as, with the water quality. In the last decade some attempts were realized to explain the rheology and the global dynamics of those mixtures, mainly in the context of mudflows and high mud concentrated suspensions. The purpose of this work is develop a rheological characterization of solid-liquid mixture (water + clay kaolinitic and water + fine sand + clay kaolinitic) with different solid volume concentrations (Cv) for which are determined, using a R/S Rheometer (Brookfield), rheological properties such as the apparent viscosity, yield stress and shear stress x shear rate curve. It was verified, under controlled conditions, the influence of the temperature, pH and solid volume concentration (Cv) on the rheological curve those mixtures, besides eventual tixotropy phenomenon and way of prepare. The rheological model adjusted for the clays was Herschel-Bulkley ( ( )n τ =τ c + k γ& ), where: τ is shear stress; τc is yield stress; k is a consistency term (apparent viscosity); n is flow index; and dy γ& = du is shear rate. It is also obtained, from a global quantitative analysis, evolution laws of the several rheologics parameters in function of the solid volume concentration. After the stage of rheological and physical characterization of mixing samples, dynamics experiments were made, under controlled conditions, than the flow of mud was observed in the open channel. These analyses were made in order to examine the behavior of parameters such as: normal depth, discharge and velocities. In fact, the experience showed that is possible to deduce wall friction laws from the rheological proprieties based on high mud concentrated suspensions and the dynamic of these muds. / Mestre

[pt] A busca de modelos de desenvolvimento que minimizem ao máximo o impacto sobre o ambiente em que vivemos é o ideal a ser alcançado. Os benefícios proporcionados através dos objetos construídos pelo homem neste ambiente são reflexos de uma interferência adequada ao espaço habitado. Neste trabalho esta interferência é produzida pelas construções habitacionais. No bairro do Monteiro, área rural do município de Itamonte-MG, notou-se um processo de deterioração e empobrecimento dos conhecimentos construtivos tradicionais, inclusive a taipa. Apesar da eficiência destas construções, observou-se a gradativa degradação de alguns modos construtivos tradicionais no local. Os conhecimentos originais, de manejo de materiais adequado ao clima e local, foram abandonados e esquecidos. O trabalho de pesquisa que se apresenta aqui tem como objetivo fazer das técnicas construtivas consagradas, e que se utilizam de solo cru, um objeto de estudo a fim de resgatar conhecimentos e procedimentos, aperfeiçoá-los, adaptá-los a determinado local e mantê-los em desenvolvimento. A aplicação da metodologia do Laboratório de Investigação em Living Design ( LILD), será a base de sustentação dos experimentos que se realizarão ao longo do trabalho. Resumidamente esta metodologia propõe primeiramente após um estudo das características do contexto local, experimentos iniciais e empíricos, em campo e em laboratório, tendo sempre a participação e atuação dos membros da comunidade. A investigação tem prosseguimento com ensaios científicos, que permitem o controle e o aperfeiçoamento nos procedimentos utilizados em tais técnicas. Posteriormente a estas etapas aplicam-se novamente outros experimentos práticos no campo e novamente com participação da comunidade. Do compartilhamento das atividades do pesquisador e dos obreiros locais, resultou uma troca de informações que permitiu a aplicação do aprendizado da produção e da pesquisa num mesmo objeto. Aparecem com destaque no percurso do trabalho, experimentos que demonstraram a importância da utilização das fibras, não somente como agente estabilizador do solo, mas permitindo sim, novas possibilidades de vedações leves, principalmente como elemento definidor de compósitos em forma de lâminas e cascas. / [en] Our goal is the search for development models that minimize environment impact. The benefits deriving from mans constructed objects on these environments reflect an adequate interference to the inhabited space. The resulting interference from habitation constructions is described. A process of deterioration and impoverishment of traditional constructive knowledge, including mud wall, was detected in the rural area of Monteiro, district of Itamonte in Minas Gerais, Brazil. In spite of the efficiency of these types of construction, the gradual degradation of some of the traditional constructive modes was verified. The original knowledge concerning the adequacy of materials to the climate and locality was abandoned and forgotten. The present research aims at studying the known constructive techniques, which use raw soil in order to recover their knowledge and procedures, to improve and adapt them to a certain place, and keep their development. The methodology of the Laboratory of Investigation in Living Design - LILD supports the experiments done along the work. In a few words, the methodology proposes a context study of local characteristics performing initial empiric experiments. This work is carried out at Monteiro and in the laboratory, always counting on the participation of community members. The investigation follows with scientific tests that allow for the control and improvement of procedures adopted in the studied techniques. The next step is to go back to the rural area and make other practical experiments, again, with the participation of community members. The result of shared activities between the researcher and local workers was the exchange of information concerning the production and the research itself, which allowed for the application of learned knowledge in the same object. Experiments along the way demonstrate the importance of utilizing fibers, not only as agents to stabilize soil, but also allowing for new light sealing possibilities, especially as main elements of composites in the form of plates and barks.

O presente trabalho teve como objeto avaliar os efeitos da aplicação de doses crescentes de lodo de esgoto de lagoas anaeróbias sobre a fertilidade do solo, disponibilidade de metais pesados no solo e produção de matéria seca, acúmulo de nutrientes e metais pesados em plantas de Sorghum bicolor L. (Moench). Os tratamentos testados foram: 1) Testemunha; 2) Fertilização Mineral; 3) L100 - Lodo de esgoto em quantidade suficiente para fornecer o nitrogênio exigido pela cultura; 4) L200 - O dobro da quantidade de lodo aplicada no tratamento 3; 5) L300 - O triplo da quantidade de lodo aplicada no tratamento 3. O experimento foi conduzido por 124 dias, em condições de casa de vegetação, sendo que o delineamento estatístico foi o bloco casualizados com 5 tratamentos e quatro repetições, totalizando 20 parcelas. Os resultados obtidos foram submetidos à análise de variância (Teste F) e, nos casos pertinentes as médias foram comparadas pelo Teste Tukey a 5% de probabilidade. Procedeu-se à realização da análise de regressão linear entre as variáveis estudadas e as doses de lodo de esgoto. Considerando-se os resultados obtidos no presente trabalho, foi possível elaborar as seguintes conclusões: - A incorporação do lodo de esgoto no solo proporcionou melhorias de algumas variáveis consideradas na avaliação da fertilidade do solo, podendo-se citar: teor de Matéria Orgânica, teor de fósforo disponível, potássio disponível e capacidade de troca de cátions. - Por outro lado, algumas variáveis, também relacionadas a fertilidade do solo, sofreram prejuízos, podendo-se citar: pH, teores de cálcio disponível, magnésio disponível e saturação por bases. Todos os elementos metálicos pesados, presentes no lodo de esgoto tiveram suas disponibilidades aumentadas no solo. - O lodo de esgoto promoveu maior produção de biomassa vegetal de ramos e folhas, panículas e raízes. - O aumento da dose de lodo proporcionou decréscimo no acúmulo de P nas ) nas folhas e ramos das plantas de sorgo granífero. Porém, nas outras partes analisadas houve aumento do acúmulo de P. Os totais acumulados de Ca e Mg não foram influenciados pelas dose de lodo de esgoto. Para os demais macronutrientes, o aumento da dose de lodo de esgoto resultou em maior acúmulo nas plantas. - Todos os metais presentes no lodo de esgoto tiveram seus acúmulos aumentados nas diferentes partes das plantas de sorgo granífero , com o aumento das doses de lodo incorporadas nos solos. Entretanto, nenhum teor encontrado foi alto o suficiente para proporcionar o surgimento de sintomas de toxicidade nas plantas. - O lodo de esgoto apresentou bom desempenho como fonte de micronutrientes para as plantas de sorgo granífero. / The object of this study was to evaluate the effects of an application of ever increasing doses of sewer mud of anaerobic ponds on soil fertiliy, the avaliability of metals in the soil, the production of dry material, the accumulation of nutrients and heavy metals in the plant, Sorghum bicolor L (Moench). The treatments tested were: 1) Witness; 2) mineral fertilization; 3) L100 - Sewer mud in sufficient quantities to provide the nitrogen required by the culture; 4) L200 - a double quantity of sewer mud applied is the treatment 3; 5) L300 - a triple quantity of sewer mud applied in the treatment 3. The experiment was conducted for 124 days in vegetation house conditions. The estatistical delineation used was that of causalized blocks of tive treatments and four repetitions, totaling 20 blocks. The abtained results were submitted to an analysis of variance (Test F) and in the pertinant cases, the averages were compared by the Tukey Test for a 5% probality. An analysis of the linear regression between the stuied variables and the doses of sewer mud were conducted. With the results obtained in this study, it was possible to e1aborate the following conclusions: - The incorporation of the sewer mud in the soil provided improvement is some variables used in the evaluation of the soil fertility; variables such as the contents of Organic Matter, the contents of avaliable Phosphorus, the contents of available Potassium and the capacity for cation exchange. - On the other hand, some variables related to soil fertility suffered losses; variables such as pH, the contents of available Calcium, of available Magnesium and base saturation. - All the heavy metal elements, present in the sewer mud, had their availability increased in the soil. - The sewer mud promoted a large production of vegetal biomass of branches, leaves, panicles and roots. - The increase of the sewer mud dose promoted the decrease in the accumulation of P in the leaves and branches of the grair producing sorghum plant. But, for the other parts analyzed, there was an increase in the accumulation of P, the accumulated totais af Calcium and Magnesium weren\'t influncied by the sewer mud dose. For the other macronutrients the increase dose of sewer mud resulted in larger accumulations in the plants. - All the heavy metals present in the sewer mud had their accumulations increased in the different parts of the grain producing sorghum plants, with the increased doses of sewer mud incorparated in the soil. However, none of contents found were high enough to promote the appearance of toxin symptons in the plants. - The ewer mud presented a good performance as a source of micronutrients for the grain producing sorghun plants.

Cette thèse a pour but l'analyse des performances d'une communication radio en présence d'évanouissements et d'effet de masque. Le masquage, du aux obstacles entre l'émetteur et le récepteur, fait varier la probabilité d'erreur moyenne ("Symbole Error Probability" SEP). L'étude de la probabilité de coupure symbole (SEO "Symbol error Outage") définie comme la probabilité que le SEP moyen excède une valeur seuil est donc plus pertinent. La difficulté de son étude réside dans le fait qu'une inversion du SEP moyen par rapport au SNR (Signal to Noise Ratio) est nécessaire. Par la méthode de Laplace nous donnons des approximations précises à tout SNR du SEP dans un canal de Nakagami-m et Rice dans le cas mono-antenne. Nous montrons ensuite que ces approximations sont inversibles par rapport au SNR et permettent d'exprimer analytiquement le SEO en fonction du SEP cible. Nous intégrons ensuite le codage canal et dérivons des expressions analytiques de la probabilité de coupure paquet pour un codage bloc puis un codage convolutif à entrée décidée. Nous étendons l'étude aux systèmes MIMO à codage bloc orthogonaux puis à multiplexage spatial où des formes exactes du SEO sont dérivées. Nous considérons le cas où des interférents sont présents. Nous dérivons une approximation précise et inversible de la probabilité d'erreur lorsque les signaux se propagent à travers un canal à évanouissements rapides de Rayleigh. Enfin parce que la prise en compte de l'interférence est un moyen avéré d'augmenter la capacité des réseaux, nous étudions les performances de la détection multiutilisateurs à maximum de vraisemblance (MUD-MLSE), dans un contexte WLAN à canaux recouvrant.

Specially designed non-damaging lost circulation pills (LCP) are being effectively applied for drilling depleted zones worldwide. Optimizing the LCP compositions stop the lost circulation effectively and protect the production zone from liquid and solids invasion significantly. Shape, particle size distribution and concentration of the lost circulation materials (LCM) are key parameters determining the effectiveness of LCP. In this study, the Permeability Plugging Apparatus (PPA) is utilized to evaluate effectiveness of various LCM&rsquo / s in curing the lost circulation. Sized calcium carbonates are used as LCM in different concentrations and in different particle size distribution. Lost circulation zones are simulated using the ceramic disks and slotted disks. Ceramic disks with nominal pore sizes 20, 35, 60, 90, and 150 microns are characterized in terms of pore size distribution using the computerized image analysis technique. Filter cake quality, spurt loss and filtrate volume are basic parameters to be evaluated in this study. Tests are performed at 75 F and 300 psi of differential.

In the most of the drilling operations it is obvious that a considerable amount of money is spent for drilling related problems / including stuck pipe, lost circulation, and excessive mud cost. In order to decrease the percentage of non-productive time (NPT) caused by these kind of problems, the aim is to control annular frictional pressure losses especially in the fields where pore pressure and fracture pressure gradient is too close which is called narrow drilling window. If we can solve these problems, the budget spent for drilling the wells will fall, therefore enabling the industry to be able to drill wells that were previously uneconomical. Managed Pressure Drilling (MPD) is a new technology that allows us to overcome these kinds of drilling problems by controlling the annular frictional pressure losses. As the industry remains relatively unaware of the full spectrum of benefits, this thesis involves the techniques used in Managed Pressure Drilling with an emphasis upon revealing several of its lesser known and therefore less appreciated applications.

Μεγάλο τμήμα της παραγόμενης ενέργειας στην Ελλάδα προέρχεται από την καύση λιγνίτη στην Βόρεια (Δυτική Μακεδονία) και Νότια (Πελοπόννησος) Ελλάδα. Η καύση του λιγνίτη έχει ως αποτέλεσμα την παραγωγή μεγάλων ποσοτήτων στερεών παραπροϊόντων, όπως η ιπτάμενη τέφρα (ΙΤ) και η τέφρα πυθμένα (ΤΠ), των οποίων η συνολική παραγωγή ανέρχεται σήμερα σε 14Mt ετησίως. Η ποσότητα των παραπροϊόντων αυτών αναμένεται να αυξηθεί τα επόμενα χρόνια εξ’ αιτίας της συνεχώς χαμηλότερης ποιότητας λιγνίτη που χρησιμοποιείται (χαμηλότερη θερμογόνος δύναμη). Ένα τμήμα της παραγόμενης ΙΤ (10-12%) στην Ελλάδα αξιοποιείται ως πρώτη ύλη στη παραγωγή τσιμέντου, ενώ η ΤΠ δεν απορροφάται μέχρι σήμερα από καμία εφαρμογή, κυρίως λόγω του υψηλού ποσοστού άνθρακα που περιέχει. Το αντικείμενο της παρούσας διατριβής είναι η αξιοποίηση, πρωτίστως, της ΤΠ και, μετέπειτα, της ΙΤ ως πρώτες ύλες στην παραγωγή τεχνητών ελαφροαδρανών για χρήση τους στην παραγωγή ελαφροσκυροδέματος. Για την παραγωγή των τεχνητών ελαφροαδρανών εφαρμόστηκε η διεργασία της πυροσυσσωμάτωσης σε σχάρα (grate sintering) έπειτα από σφαιροποίηση μιγμάτων των δύο τεφρών. Πραγματοποιήθηκε διερεύνηση των φυσικοχημικών χαρακτηριστικών των λιγνιτικών τεφρών (Κεφάλαιο 2) με σκοπό τον προσδιορισμό και την κατανόηση των χαρακτηριστικών τους, τα οποία αναμένεται να έχουν σημαντική επίδραση στην εφαρμογή της διεργασίας και στην ποιότητα του παραγόμενου προϊόντος. Επιπλέον, γίνεται αναλυτική αναφορά στα βασικά χαρακτηριστικά των διεργασιών σφαιροποίησης και πυροσυσσωμάτωσης (Κεφάλαιο 3). Για την εφαρμογή της επιλεγμένης διεργασίας παραγωγής τεχνητών ελαφροαδρανών πραγματοποιήθηκε σχεδιασμός μιγμάτων με διαφορετικές αναλογίες ΤΠ και ΙΤ (Κεφάλαιο 4). Ο περιεχόμενος άνθρακας της ΤΠ αποτελεί το καύσιμο της διεργασίας πυροσυσσωμάτωσης, ενώ η υψηλή περιεχόμενη υγρασία της ΤΠ αξιοποιείται ως το κύριο συνδετικό υλικό κατά την διάρκεια σφαιροποίησης για τον σχηματισμό σφαιριδίων. Οι διαφορετικές αναλογίες ΤΠ και ΙΤ αντιστοιχούν σε διαφορετικό ποσοστό στερεού καυσίμου στο μίγμα (προκύπτει από τις διαφορετικές vi αναλογίες), μία παράμετρος η οποία έχει επίδραση στην ολοκλήρωση της πυροσυσσωμάτωσης και στην ποιότητα του παραγόμενου (ελαφροαδρανούς) προϊόντος. Η πυροσυσσωμάτωση ολοκληρώθηκε με επιτυχία με ελάχιστο ποσοστό στερεού καυσίμου (περιεχόμενο άνθρακα ΤΠ) 6.5%κβ (Κεφάλαιο 5). Πραγματοποιήθηκε φυσικοχημικός χαρακτηρισμός όλων των προϊόντων της πυροσυσσωμάτωσης των μιγμάτων λιγνιτικών τεφρών της Μεγαλόπολης, και διαπιστώθηκε ότι το ποσοστό περιεχόμενου άνθρακα της ΤΠ είναι μια πολύ σημαντική παράμετρος για την παραγωγή ελαφροαδρανών υλικών. Ο σχηματισμός πορώδους δομής στο εσωτερικό των πυροσυσσωματωμένων πελλετών, στην οποία οφείλεται και το χαμηλό βάρος των παραγόμενων αδρανών, προκαλείται από την ταυτόχρονη εξέλιξη δύο διεργασιών: α) την παραγωγή αερίων σε υψηλές θερμοκρασίες και β) τον σχηματισμό ρευστής φάσης στην εξωτερική επιφάνεια της πελλέτας στο ίδιο χρονικό διάστημα (Κεφάλαιο 6). Οι αντοχές των πυροσυσσωματωμένων πελλετών οφείλονται σε αντιδράσεις και στον σχηματισμό νέων φάσεων είτε στερεών μέσω διάχυσης είτε ρευστών που προέρχονται από επιτήξεις στα όρια των κόκκων. Στην συνέχεια τα παραγόμενα ελαφροαδρανή χρησιμοποιήθηκαν για την παραγωγή δοκιμίων θερμομονωτικού και δομικού ελαφροσκυροδέματος και πραγματοποιήθηκε έλεγχος των θερμικών και μηχανικών τους ιδιοτήτων, αντίστοιχα (Κεφάλαιο 7). Τα αποτελέσματα δείχνουν ότι τα τεχνητά ελαφροαδρανή μπορούν να χρησιμοποιηθούν για την παραγωγή θερμομονωτικού και δομικού ελαφροσκυροδέματος. Η επιτυχής παραγωγή τεχνητών ελαφροαδρανών από μίγματα λιγνιτικών τεφρών Μεγαλόπολης αποτέλεσε και την βάση για δοκιμές πυροσυσσωμάτωσης των παραπροϊόντων αυτών με άλλα στερεά βιομηχανικά παραπροϊόντα όπως η ερυθρά ιλύς (ΕΙ), η οποία παράγεται από την επεξεργασία βωξίτη προς παραγωγή αλουμινίου (Κεφάλαιο 8). Για την διαπίστωση της συνεργασίας των δύο διαφορετικών παραπροϊόντων πραγματοποιήθηκε προσθήκη μέχρι και 30%κβ ΕΙ σε μίγματα λιγνιτικών τεφρών. Πραγματοποιήθηκε φυσικοχημική διερεύνηση των προϊόντων της πυροσυσσωμάτωσης και χρήση τους στην παραγωγή δοκιμίων σκυροδέματος. Τα αποτελέσματα δείχνουν ότι η αύξηση της προστιθέμενης ΕΙ στο μίγμα λιγνιτικών vii τεφρών της Μεγαλόπολης επιφέρει αύξηση στο βάρος των παραγόμενων αδρανών, ενώ μπορούν να χαρακτηριστούν ελαφροαδρανή τα προϊόντα πυροσυσσωμάτωσης μιγμάτων μέχρι και 20%κβ προσθήκης ΕΙ. Τα αποτελέσματα των μετρήσεων των μηχανικών αντοχών των δοκιμίων σκυροδέματος δείχνουν ότι η ΕΙ επιφέρει αύξηση στις αποκτώμενες αντοχές σε ποσοστό προσθήκης μέχρι και 15%κβ. Η εφαρμογή που προτείνεται σε αυτή την διατριβή για την παραγωγή τεχνητών ελαφροαδρανών υλικών από τα στερεά λιγνιτικά παραπροϊόντα του ΑΗΣ Μεγαλόπολης αποτελεί την πρώτη πρόταση για αξιοποίηση της ΤΠ στην Ελλάδα. Η πυροσυσσωμάτωση μιγμάτων των λιγνιτικών τεφρών μπορεί να οδηγήσει στην παραγωγή τεχνητών ελαφροαδρανών για χρήση τους στο δομικό και θερμομονωτικό ελαφροσκυρόδεμα ενώ ο περιεχόμενος άνθρακας της ΤΠ, ο οποίος αξιοποιείται ως το καύσιμο διεργασίας παραγωγής, αποτελεί σημαντική παράμετρο για την ποιότητα των τεχνητών ελαφροαδρανών. Επιπλέον, οι λιγνιτικές τέφρες της Μεγαλόπολης μπορούν να συνεργαστούν με άλλα στερεά βιομηχανικά παραπροϊόντα όπως η ΕΙ για την παραγωγή τεχνητών ελαφροαδρανών διαφορετικής ποιότητας. Επίσης, η συγκεκριμένη πρόταση αφορά στην μαζική αξιοποίηση της ΤΠ και πιθανή εφαρμογή έχει την δυνατότητα να απορροφήσει το μεγαλύτερο τμήμα του παραγόμενου αυτού παραπροϊόντος. / Large part of energy demand in Greece is covered by lignite combustion in West Macedonia and Peloponnesus. Lignite combustion results in production of, approximately, 14Mt/year of solid byproducts, such as fly ash (FA) and bottom ash (BA). The quantity of these byproducts is going to be increased in future because of the low quality of available lignite (lower calorific value). Part of FA (10-12%) produced in Greece is utilized as raw material in cement production while there is no application of BA, mainly because of its high carbon content. This study investigates a new method for utilization of BA, primarily, and FA, afterwards, as raw materials in the production of lightweight aggregates and further utilization of produced aggregates in lightweight aggregate concrete. A two stage process, pelletization and sintering, is applied in BA and FA mixtures. Physical and chemical analyses of Megalopolis lignite ashes are performed (Chapter 2) in purpose of characterization of process raw materials. Furthermore, fundamental theory of pelletization and grate sintering is presented (Chapter 3) in purpose of better understanding of process details. Mixtures of different BA/FA ratio are prepared for sintering tests (Chapter 4). Carbon contained in BA is utilized as the fuel of the process, while high water content of BA is utilized as the primary binding material during pelletization in purpose of pellets formation. Different BA/FA ratios represent different solid fuel percentages in sintering mixtures. This is an important parameter, which strongly affects the completion of the process and the quality of product. Successful completion of sintering process is achieved with minimum solid fuel content (BA carbon) 6.5wt% in mixture (Chapter 5). Physical and chemical characterization is performed for products of all different sintering mixtures. The results show that BA carbon content is an important parameter for the production of lightweight aggregates. Porous structure formation inside the sintered pellets, which is responsible for aggregates low weight, is caused by simultaneous development of two different processes: a) production of gases in high temperatures and, b) liquid (glassy) phase formation in the outer part of pellets in the same time period (Chapter 6). ix Formation of either solid state bonds, through diffusion, and/or glassy phase bonds at the points of particles mutual contact are responsible for pellet strength. Lightweight aggregates produced are used in the production of insulating and structural lightweight aggregate concrete specimens and thermal and mechanical tests are performed, respectively. According to tests results artificial lightweight aggregates can be used for insulating and structural purposes. The successful experimental results from the utilization of lignite solid byproducts in the production of LWA offered new opportunities for collaboration of these byproducts with other industrial solid residues, such as red mud (RM) which is produced during bauxite treatment for aluminum production (Chapter 8). In purpose of investigation of collaboration of these different byproducts sintering mixtures are prepared with low RM addition, up to 30wt%, in lignite ashes mixtures. Physical and chemical characterization is performed for products of all sintering mixtures and they are used for production of concrete specimens. Results show that increase of RM addition brings increase in aggregates weight, while aggregates formed by RM addition up to 20wt% can be considered as lightweight ones. The results of mechanical strength tests in concrete specimens show that RM addition up to 15wt% brings increase in aggregates strength. This is the first proposed method for utilization of lignite BA in Greece in the production of lightweight aggregates. Sintering of mixtures of lignite ashes results to the production of lightweight aggregates and the produced aggregates can be used for insulating and structural lightweight aggregate concrete. BA carbon content, which is utilized as the fuel of the process, is an important parameter for lightweight aggregate production and porous structure formation. Furthermore, Megalopolis lignite ashes can be treated in collaboration with other industrial solid byproducts, such as RM for the production of lightweight aggregates of different quality. Finally, the proposed method targets to massive utilization of BA produced in Megalopolis power station.

Στην παρούσα Διατριβή παρουσιάζεται η μελέτη της δυνατότητας αξιοποίησης της ερυθράς ιλύος, ΕΙ, η οποία παράγεται κατά τη διαδικασία παραγωγής της αλουμίνας με τη διεργασία Bayer, για την παραγωγή δομικών παραδοσιακών κεραμικών, κύρια τούβλων και κεραμιδιών. Μελετήθηκαν αργιλούχα μίγματα με ΕΙ για ποσοστά ΕΙ από 10%κβ έως και 100%κβ.Επιγραμματικά, για την ΕΙ, πραγματοποιήθηκε χαρακτηρισμός και μελέτη της θερμικής συμπεριφοράς της. Για τα μίγματα της ΕΙ με αργιλούχες Α' ύλες, πραγματοποιήθηκε θεωρητικός σχεδιασμός τους, ενώ μελετήθηκε η επίδραση των σταδίων ανάμιξης και λειοτρίβησης, η επίδραση της ΕΙ στην πλαστικότητα, η θερμική συμπεριφορά, οι φυσικομηχανικές ιδιότητες των τελικών κεραμικών, η επίδραση της θερμοκρασίας και ατμόσφαιρας όπτησης καθώς και η περιβαλλοντική τους συμπεριφορά. Πραγματοποιήθηκαν επιπρόσθετα πιλοτικές δοκιμές παραγωγής τούβλων και κεραμιδιών. Τα αποτελέσματα της διατριβής, οδήγησαν στην ανάπτυξη μιας βέλτιστης διεργασίας παραγωγής κεραμικών με ΕΙ, η οποία αφορά στο σχεδιασμό του μίγματος με ΕΙ και την όπτησή του σε αναγωγικές συνθήκες. / In the present thesis, Bayer's process red mud, RM, is being studied as an additive and raw material for the production of heavy clay ceramics, mainly bricks and roofing tiles. A number of clay mixtures with RM were studied, for a RM content ranging from 10wt% to 100wt%. In summary, RM was characterised and studied for its thermal behaviour whereas, for the clay mixtures with RM, their design is provided, and the effect of comminution steps, the effect of RM on plasticity, their thermal behaviour, the influence of firing temperature and atmosphere, the physicomechanical properties of the end bodies, as well as their environmental behaviour are studied. In addition, pilot plan scale experiments were performed for the production of bricks and roofing tiles. The results of this thesis, led to the development of an optimised process for the production of ceramics with RM, which emphasises on the design of the body mixture as well as on the firing in reducing conditions.

No description available.

Access to abstract permanently restricted to Ball State community only / Access to thesis permanently restricted to Ball State community only / Department of Natural Resources and Environmental Management