Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Neste trabalho utilizou-se frutos de bacuri (Platonia insignis Mart.), provenientes da RegiÃo Meio-Norte e preparaÃÃes enzimÃticas comerciais, cedidas pela Novo Nordisk e Quest international. A pesquisa teve inÃcio com a caracterizaÃÃo da polpa de bacuri âin naturaâ por meio de determinaÃÃes analÃticas de ordem quÃmicas e fÃsico-quÃmicas. Em seguida, cinco preparaÃÃes enzimÃticas comerciais (Pectinex AR, Pectinex Ultra SP-L, Biopectinase CCM, Ultrazym AFP-L e Viscosyme L) foram caracterizadas quanto as atividades de poligalacturonase, pectinametilesterase, pectinaliase, celulase, invertase e xilanase. O processo de maceraÃÃo da polpa de bacuri foi realizado a partir de diversos estudos para a seleÃÃo da preparaÃÃo enzimÃtica comercial ideal e a definiÃÃo dos parÃmetros de tempo e concentraÃÃo enzimÃtica, razÃo polpa:Ãgua e tempo de homogeneizaÃÃo, cujo procedimento baseou-se na quantificaÃÃo de grupos redutores totais (GRT), consistÃncia e teor de polpa. Definidos estes parÃmetros, procedeu-se a etapa de branqueamento para inativar as enzimas apÃs a maceraÃÃo. Foi realizada caracterizaÃÃo fÃsico-quÃmica e quÃmica da polpa diluÃda, bem como da polpa diluÃda/macerada e da polpa diluÃda/macerada/branqueada para efeitos comparativos, alÃm de anÃlises microbiolÃgicas. Foram formulados quatro nÃctares, sendo o primeiro com 10% de polpa e sem adiÃÃo de preparaÃÃo enzimÃtica e os outros trÃs com 10, 20 e 30% de polpa com adiÃÃo de preparaÃÃo enzimÃtica. Estes nÃctares foram submetidos à avaliaÃÃo sensorial quanto à impressÃo global e diagnÃstico dos atributos para a avaliaÃÃo da doÃura e a intensidade do sabor residual e da consistÃncia. Os resultados revelaram que a polpa de bacuri pode ser considerada uma apreciÃvel fonte de alimentos. As condiÃÃes de 25 U/mL de PG de Viscozyme L, com 40 minutos de tratamento enzimÃtico, diluiÃÃo polpa/Ãgua 1:2 e homogeneizaÃÃo de 20 segundos apresentaram um nÃvel adequado para a maceraÃÃo da polpa. A anÃlise sensorial mostrou que à possÃvel formular um nÃctar com, pelo menos 20% de polpa por meio da adiÃÃo de preparaÃÃes enzimÃticas comerciais. / In this work, bacuri fruits (Platonia insignis Mart.) from the midnorthern region have been used together with commercial enzymatic preparations kindly donated by Novo Nordisk and Quest International. Research began with a bacuri pulp characterization âin naturaâ through chemical and physicochemical analysis .Pectinex AR, Pectinex Ultra SP-L, Biopectinase CCM, Ultrazym AFP-L and Viscosyme L were analyzed in regards to polygalacturonase, pectinmetilesterase, pectinliase, cellulose, invertase and xilanase activity. The process of bacuri pulp maceration was carried out with basis on different studies for ideal commercial enzymatic preparation selection and enzymatic preparation and timing parameters, pulp/water ratio and homogenization time. This process was based on total reducer group (GRT) quantification, consistence and pulp content. Once these parameters were defined, the whitening stage was initiated with the objective of deactivating enzymes after maceration. Diluted pulp physicochemical and chemical characterizations were performed, as well as macerated pulp and diluted/macerated whitened pulp characterization for comparative purposes, together with microbiological analysis. Four nectars were formulated, being the first one with 10% pulp without enzymatic preparation addition and the other three with 10%, 20% and 30% pulp with addition of enzymatic preparation. These nectars were submitted to sensorial evaluation, global impression and feature diagnosis for sweetness, residual flavor consistence and intensity evaluation. Results demonstrated that bacuri pulp can be a considerable food source. 800 ppm of Viscozyme L (25 U/mL of polyigalacturonase), with 40 minutes of enzymatic treatment, pulp/water dilution 1:2 and 20 second homogenization, presented an appropriate level for pulp maceration. Sensorial analysis showed that it is possible to prepare nectar with at least 20% of pulp by adding commercial enzymatic preparations.

A extração e processamento de minério resultam na geração de elevadas quantidades de resíduos, cuja disposição gera impacto e risco ambiental. O lançamento direto em reservatórios contidos por diques consiste na forma mais comum de disposição dos resíduos de mineração em superfície. Estes diques podem ser construídos por alteamentos sucessivos a montante (upstream), prática desaconselhada em alguns países. Apesar de se tratar de um processo de baixo custo, o tipo de aterro a montante é uma operação de risco, pois a montante as barragens são sensíveis à liquefação e também porque a estabilidade das barragens pode ser ameaçada pelo excesso de poro pressão gerado dentro do depósito durante a construção. Para atender às exigências de projetos de áreas de disposição de resíduos é, portanto, fundamental entender o comportamento destes materiais. Resíduos exibem considerável variabilidade em suas características físicas, químicas e mineralógicas, que conferem um comportamento distinto dos geomateriais usualmente encontrados em depósitos naturais. Entre os diferentes resíduos destacam-se ouro e bauxita cuja prática de exploração no Brasil é revestida de considerável interesse econômico e ambiental. Nesta tese estes materiais são analisados a partir de uma extensa campanha de investigação geotécnica baseada em um programa de ensaios de laboratório destinados à caracterização destes resíduos e à definição de parâmetros constitutivos. Para fins comparativos são realizados ensaios com um material siltoso, porém inerte. A condutividade hidraúlica e compressibilidade dos resíduos foram obtidas através de ensaios oedométricos executados com estágios de carga e gradientes hidráulicos constantes. Ensaios triaxiais foram realizados com altos níveis de tensões de confinamento e distintas trajetórias de tensões, para a definição da linha do estado crítico e a identificação do comportamento destes materiais através de ensaios com Bender Elements. A análise dos resultados obtidos permitiu comparações entre a linha de consolidação oedométrica (LCO), a linha de consolidação isotrópica (LCI) e a linha do estado crítico (LEC) que definiram a resposta de liquefação estática do material. No espaço e - log (p´) o aparecimento de um comportamento instável alterou significativamente a inclinação da LEC com relação a LCI e a LCO. A mesma mudança de inclinação é observada tanto no parâmetro de estado como no módulo cisalhante do solo quando plotados contra a tensão efetiva média. Com base nessas evidências, é defendido que o LEC de resíduos de mineração é altamente não-linear, e servem como indicativo de três respostas distintas do solo: uma resposta estável quando LCO, LCI e a LEC exibem paralelismo, um comportamento meta-estável em baixas tensões de confinamento levando à liquefação e quebra de grãos para altas tensões de confinamento da amostra. O avanço nas pesquisas relativas à disposição de resíduos provenientes de indústrias de mineração com o conhecimento dos fenômenos que se processa, poderá evitar a ocorrência de ruptura de barragens, que teria como conseqüência desastres ambientais de grande impacto. / Production and deposition of mining tailings is a problem confronting geotechnical engineers given the dimension of tailings deposits and environmental risks. The direct launching of tailings in reservoirs contained by dikes consists in a common type of waste disposal. These dikes can be constructed by successive upstream embankments, a relatively simple and economical process adopted in some countries. Although it is a low cost process, the upstream embankment is an operation of great risk, especially because tailings are susceptible to liquefaction and also because the stability of the dams can be threatened by excess of pore pressures generated inside the deposit during construction. To meet design requirements of disposal of residues it is therefore essential to understand the behavior of these materials. Tailings show a considerable variability in their physical, chemical and mineral characteristics that confer a distinct behavior to the geo-materials usually found in natural deposits. The present work gives emphasis to gold and bauxite tailings that encompass substantial economic and environmental interest in Brazil. In the thesis, an extensive laboratory geotechnical investigation program is carried out in an attempt to characterize these residues and to establish design constituent parameters. For comparative purposes an inert silty material is also tested. Compressibility and hydraulic conductivity were measured in oedometer tests performed at constant load and constant hydraulic gradient tests. Triaxial tests were carried out at high stress levels and different stress paths in order to establish the position and shape of the critical state line. In addition measured with Bender Elements are evaluated. The results between the oedometer consolidation (OCL), isotropic consolidation (ICL) and critical sate (CSL) lines allowed the static liquefaction response to be directly assessed. In a e-log (p’) space, the onset of a meta-stable behaviour significantly changes the slope of the CSL relative to both ICL and OCL. The same change in slope is observed on both the state parameter and the small strain shear modulus measured by bender elements when plotted against mean stress. Based on these evidences it is advocated that the CSL of the tailing is highly non-linear in nature, which lead to three distinct soil responses: a stable response when OCL, ICL and CSL exhibit similar slopes, a meta-stable beahaviour at lower stress leading to liquefaction and a crushable response for higher mean stresses. Advanced research on tailings from mining industries with due recognition of the phenomena of liquefaction may prevent dam failure, and consequently may prevent major environmental disasters.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Neste trabalho utilizou-se frutos de bacuri (Platonia insignis Mart.), provenientes da RegiÃo Meio-Norte e preparaÃÃes enzimÃticas comerciais, cedidas pela Novo Nordisk e Quest international. A pesquisa teve inÃcio com a caracterizaÃÃo da polpa de bacuri âin naturaâ por meio de determinaÃÃes analÃticas de ordem quÃmicas e fÃsico-quÃmicas. Em seguida, cinco preparaÃÃes enzimÃticas comerciais (Pectinex AR, Pectinex Ultra SP-L, Biopectinase CCM, Ultrazym AFP-L e Viscosyme L) foram caracterizadas quanto as atividades de poligalacturonase, pectinametilesterase, pectinaliase, celulase, invertase e xilanase. O processo de maceraÃÃo da polpa de bacuri foi realizado a partir de diversos estudos para a seleÃÃo da preparaÃÃo enzimÃtica comercial ideal e a definiÃÃo dos parÃmetros de tempo e concentraÃÃo enzimÃtica, razÃo polpa:Ãgua e tempo de homogeneizaÃÃo, cujo procedimento baseou-se na quantificaÃÃo de grupos redutores totais (GRT), consistÃncia e teor de polpa. Definidos estes parÃmetros, procedeu-se a etapa de branqueamento para inativar as enzimas apÃs a maceraÃÃo. Foi realizada caracterizaÃÃo fÃsico-quÃmica e quÃmica da polpa diluÃda, bem como da polpa diluÃda/macerada e da polpa diluÃda/macerada/branqueada para efeitos comparativos, alÃm de anÃlises microbiolÃgicas. Foram formulados quatro nÃctares, sendo o primeiro com 10% de polpa e sem adiÃÃo de preparaÃÃo enzimÃtica e os outros trÃs com 10, 20 e 30% de polpa com adiÃÃo de preparaÃÃo enzimÃtica. Estes nÃctares foram submetidos à avaliaÃÃo sensorial quanto à impressÃo global e diagnÃstico dos atributos para a avaliaÃÃo da doÃura e a intensidade do sabor residual e da consistÃncia. Os resultados revelaram que a polpa de bacuri pode ser considerada uma apreciÃvel fonte de alimentos. As condiÃÃes de 25 U/mL de PG de Viscozyme L, com 40 minutos de tratamento enzimÃtico, diluiÃÃo polpa/Ãgua 1:2 e homogeneizaÃÃo de 20 segundos apresentaram um nÃvel adequado para a maceraÃÃo da polpa. A anÃlise sensorial mostrou que à possÃvel formular um nÃctar com, pelo menos 20% de polpa por meio da adiÃÃo de preparaÃÃes enzimÃticas comerciais. / In this work, bacuri fruits (Platonia insignis Mart.) from the midnorthern region have been used together with commercial enzymatic preparations kindly donated by Novo Nordisk and Quest International. Research began with a bacuri pulp characterization âin naturaâ through chemical and physicochemical analysis .Pectinex AR, Pectinex Ultra SP-L, Biopectinase CCM, Ultrazym AFP-L and Viscosyme L were analyzed in regards to polygalacturonase,pectinmetilesterase, pectinliase, cellulose, invertase and xilanase activity. The process of bacuri pulp maceration was carried out with basis on different studies for ideal commercial enzymatic preparation selection and enzymatic preparation and timing parameters, pulp/water ratio and homogenization time. This process was based on total reducer group (GRT) quantification, consistence and pulp content. Once these parameters were defined, the whitening stage was initiated with the objective of deactivating enzymes after maceration. Diluted pulp physicochemical and chemical characterizations were performed, as well as macerated pulp and diluted/macerated whitened pulp characterization for comparative purposes, together with microbiological analysis. Four nectars were formulated, being the first one with 10% pulp without enzymatic preparation addition and the other three with 10%, 20% and 30% pulp with addition of enzymatic preparation. These nectars were submitted to sensorial evaluation, global impression and feature diagnosis for sweetness, residual flavor consistence and intensity evaluation. Results demonstrated that bacuri pulp can be a considerable food source. 800 ppm of Viscozyme L (25 U/mL of polyigalacturonase), with 40 minutes of enzymatic treatment, pulp/water dilution 1:2 and 20 second homogenization, presented an appropriate level for pulp maceration. Sensorial analysis showed that it is possible to prepare nectar with at least 20% of pulp by adding commercial enzymatic preparations.

Auf den Innenkippen nehmen mit dem Anstieg des Grundwassers die Zahl der Verflüssigungsereignisse und auch die Größe der verflüssigten Bereiche zu. Besonders davon betroffen ist der sogenannte Nordraum der Lausitz südlich von Lübbenau. Dort wurden deshalb Böschungskonturen vor und nach den Verflüssigungsereignissen über Jahre systematisch erfasst. Die erfassten Konturen wurden geokinematisch analysiert, um charakteristische Bewegungsmuster erkennen und beschreiben zu können. Das Ergebnis ermöglicht eine neue Klassifizierung der auf Innenkippen auftretenden Verformungsvorgänge. Darauf aufbauend, entstand eine neue Methodik zur Berechnung der Standsicherheit verflüssigungsgefährdeter Innenkippenflächen deren Basis die Theorien des Erddrucks und Hydromechanik sind. Für den Nachweis des horizontalen Gleichgewichts einer Böschung wird ein Kräfte-, für das der vertikalen, ein Momentenvergleich hergeleitet. Mit einem hydromechanischen Ansatz ist es auch möglich, zusätzlich die Endgeometrie der sich nach der Verflüssigung einstellenden Böschung zu berechnen. Die Ergebnisse der Standsicherheitsberechnungen und der geometrischen Endkonturen zeigen überraschende Übereinstimmungen mit den erfassten gegangenen Böschungsbewegungen.

The behaviour of cohesionless soils is known to be influenced by the method of reconstitution. It is generally accepted in the literature that different reconstitution methods produce samples of varying fabric and thus samples of varying behaviour. Very little evidence has been presented to validate this statement. The main aim of this is thesis is firstly to observe the fabric of in situ and reconstituted gold tailings samples and secondly to investigate the difference in behaviour between these samples at the same state. The investigation focused on testing in situ and reconstituted gold tailings samples obtained from 3 positions on a tailings dam; pond, middle beach and upper beach. Laboratory reconstitution methods included moist tamping and slurry deposition. Fabric analysis involved the use of SEM images to classify the observed differences in the fabric of the undisturbed and reconstituted gold tailings samples. A particle interaction model based on the observed fabric was postulated to explain the differences or similarities in behaviour. The scope of behaviour investigated included sedimentation, collapse and swell, consolidation and compressibility, creep, stiffness and shear behaviour. The fabric analysis indicates that differences in the fabric of undisturbed and reconstituted gold tailings samples are visible. Moist tamping produces an aggregated fabric while slurry deposition yields a homogeneous fabric similar to that of the undisturbed samples. Comparison of behaviour indicates that neither moist tamping nor slurry deposition can replicate the behaviour of the undisturbed sample fully. Consolidation and compression is a function of the fabric while friction angle is independent of the fabric. Available shear strength and liquifaction potential is also affected by the preparation method and the resulting fabric. / Thesis (PhD)--University of Pretoria, 2009. / Civil Engineering / PhD / Unrestricted

South Africa, as one of the world’s largest gold producing countries, also generates large amounts of tailings. These tailings are disposed in tailings dams, which pose great threat to the environment in the case of failure, in particular, liquefaction. In order to evaluate the potential of liquefaction, the void ratio of the tailings is required and is often impossible to obtain. Seismic methods allow an indirect method to estimate void ratio of in situ deposits of which tailings are examples of. Currently, the use of seismic methods to estimate void ratio of tailings rely on shear wave velocity – void ratio relationships derived for sands. It is thus uncertain whether this relationship holds for gold tailings, which is classified as a sandy silt or silt. The measurement of shear wave velocity of tailings is done in the laboratory using a triaxial apparatus modified to accommodate bender element. Shear wave velocities are measured using wide square pulses and continuous sinusoidal waves. The results show that there is a near linear relationship between void ratio and shear wave velocity normalized against effective stress. The position of this relationship lies below the previously published results for sands. Shear wave velocity of gold tailings is more sensitive to changes in effective stress than changes in void ratio or over-consolidation ratio. Furthermore, using phase sensitive detection of continuous waves, we can conclude that shear wave velocity of gold tailings is also frequency dependent. / Dissertation (MEng)--University of Pretoria, 2006. / Civil Engineering / MEng / Unrestricted

A geração de resíduos provocada pela atividade mineradora é revestida de considerável preocupação ambiental, tanto em função da área envolvida no depósito deste material, quanto pelos impactos causados por eventuais rupturas que possam a ocorrer nestes reservatórios. O método de disposição de resíduos, frequentemente utilizado pelas mineradoras, consiste no bombeamento do material por via úmida até os reservatórios de alteamento contidos através de diques ou barragens. Este processo pode tornar estas áreas suscetíveis à ocorrência de rupturas causadas por liquefação do material. Quando este tipo de evento acontece, tem-se um aumento repentino da poropressão, com consequente redução da resistência ao cisalhamento. A verificação do potencial de liquefação de resíduos de mineração é, portanto, imprescindível à prevenção de impactos ambientais, além de colaborar na execução de projetos geotécnicos mais seguros e econômicos. Neste trabalho são analisados três reservatórios distintos, sendo um composto por resíduo de mineração de ouro e os outros dois por resíduo de mineração de bauxita. Os resultados de ensaios realizados em campo (SCPTU/CPTU e SDMT) são utilizados na avaliação geotécnica dos resíduos, buscando-se verificar a compatibilidade com avaliações já realizadas através de ensaios de laboratório. O potencial de liquefação estática dos materiais é observado em laboratório para baixos níveis de tensões, demonstrando que os resíduos são suscetíveis à liquefação estática. Este comportamento é verificado também na interpretação de ensaios de campo, interpretados através de correlações de natureza semiempírica baseadas na combinação de uma medida representativa de pequenas deformações (módulo cisalhante) combinado a uma medida obtida à grandes deformações (resistência à penetração) que, combinadas, permitem a determinação do parâmetro de estado do material. A primeira proposta consistiu na definição de uma fronteira entre materiais de comportamento contrátil e dilatante no espaço G0/qc versus p’/pa. Esta proposta apresentou uma resposta adequada, entretanto, a concentração de todos os pontos referentes aos resíduos analisados, possivelmente suscetíveis ao fenômeno de liquefação estática, numa mesma região gráfica, somente foi possível no espaço G0/qc versus qc1. Neste espaço a separação entre materiais de comportamento dilatante e contrátil foi possível com a inserção de uma fronteira empírica. Este estudo demonstrou a boa sensibilidade dos parâmetros G0 e qc ao fenômeno de liquefação estática. A suscetibilidade à liquefação cíclica dos resíduos de mineração de ouro e bauxita também foi verificada através de correlações com resultados de ensaios de campo. Esta análise indicou a possibilidade de ocorrência do fenômeno para os mais baixos níveis de magnitude de sismo atuante. / Waste generation caused by mining activity emerges as an environmental concern, both because of the large area involved in deposits of this material, as well as the possible impacts caused by occasional failures that may occur in these deposits. The method of waste disposal, often used by mining companies, consists by pumping wet material in sequence until completion of the reservoirs contained by dikes or dams. This process makes these areas susceptible to the occurrence of the liquefaction failures. When this type of event happens there is a sudden increase in pore pressure with consequent reduction shear strength, which can result is risk of containment structures. Therefore, verification of liquefaction potential of these materials is essential in the prevention of environmental impacts. The present work analyzes three different reservoirs, one consisting of gold mining tailings and the other two of bauxite mining tailings. The results of field tests (SCPTU/ CPTU and SDMT) are used in geotechnical evaluation of tailings in order to verify the compatibility with evaluations already carried out through laboratory tests. The static liquefaction potential observed in laboratory at low levels of stresses is consistent with field assessment from in situ tests. Semiempirical correlations based on field tests are based on small strain measurements (shear modulus) combined with large strain measurements (penetration resistance), that are used to defined the state parameter of the material. The first proposal consisted in defining a boundary between materials of contractive and dilatant behavior in space G0/qc versus p’/pa. The proposal presented an appropriate response, however, the concentration of all analyzed points, possibly susceptible to static liquefaction phenomenon, in the same graphical region was only possible in space G0/qc versus qc1. In this space the separation between materials of contractive and dilatant behavior was possible with the inclusion of an empirical boundary. This study demonstrated the good sensitivity of the parameters G0 and qc to the static liquefaction phenomenon. The cyclic liquefaction susceptibility of the gold and bauxite mining tailings was also verified by correlation with field tests results. This analyzes indicated the possibility of occurrence of the phenomenon to the lowest levels of earthquake magnitude.

The energy consumption in the world is increasing at the same time as the fossil fuel resources are limited. This is causing a rising interest in renewable energy sources over the world. To reduce dependency on fossil fuel sources biomass is an excellent alternative.SCA Östrand pulp mill in Timrå is having one of the largest industrial investments made in Sweden. The production capacity will double, resulting in the largest production line for bleached softwood kraft pulp in the world. This level will be reached in 2020. The large expansion has given an interest for a possible localization of a biorefinery in connection with the existing pulp mill. This project was one of the first investigations towards building a biorefinery at SCA Östrand pulp mill.The aim of this project was to investigate liquefaction of bark from spruce from SCA Ortviken paper mill by solvent solubilization of lignin. It was desirable to hydrolyze all cellulose in the media used, with or without the use of solid catalyst. Many different catalysts together with solvents were investigated with the goal to find the best suitable combination to be used in a biorefinery of softwood bark. The investigated solvents were para-toluenesulfonic acid and methanol. Today bark is usually burned for heat recovery at the pulp and paper mill.Analysis of extractives, ash metals and carbohydrates of the bark were performed before any trials. Reactions took place in a 0.3 L stainless steel Parr reactor with high temperature and pressure. Several trials (21 in total) were made with or without catalyst and most of them with methanol as solvent. Two catalysts were studied in more detail, zeolite ZSM-5 and zeolite Beta_250. For ZSM-5 mainly methyl esters and steroid hydrocarbons were formed. Reactions with Beta_250 resulted in monolignols, shorter methyl esters and shorter organic acids compared with ZSM-5.The result showed most liquid product and lowest bark and coke residue from zeolite ZSM-5 and Ni/C-catalyst with 0.16 g respectively 0.21 g bio-oil, both from 1 g of softwood bark.

[pt] A disposição de rejeitos tem sido uma preocupação muito importante nas empresas de mineração de todo o mundo, tendo como principal motivo a proteção do meio ambiente. Diariamente geram-se grandes quantidades de rejeitos nas plantas de beneficiamento de minérios, sendo necessário dispor de estruturas de armazenamento adequadas (barragem de rejeito) que, dependendo da produção industrial, devem ser alteadas para aumentar a capacidade de armazenamento destas estruturas. Três métodos de alteamento de barragens podem ser utilizados: o método à montante, o método à jusante e o método da linha de centro. O método à montante, discutido nesta dissertação, começa com a construção de um dique de partida. Terminada esta etapa, os rejeitos são depositados à montante, formando uma praia que adensará com o tempo, aumentando gradualmente a resistência ao cisalhamento do rejeito e servindo de fundação para futuros diques de alteamento. Este procedimento continua sucessivamente, até atingir a cota prevista de projeto. É um método de construção simples e de baixo custo, mas sua principal desvantagem é que velocidades de alteamento excessivas podem induzir a liquefação estática, causa principal do colapso de várias barragens de rejeito construídas no mundo. Neste trabalho é investigado o potencial de liquefação de uma barragem de rejeito de cobre, situada no Peru, com auxílio do método empírico de Olson, baseado em correlações com resultados de ensaios de campo SPT, e do método de elementos finitos, com utilização do modelo constitutivo elastoplástico UBCSand para previsão de liquefação. / [en] The disposal of tailings has been a very important concern in mining companies around the world, with the main objective to protect the environment. Large quantities of tailings are generated daily in the ore processing plants, being necessary the availability of specific storage structures (tailings dam) which, depending on the industrial production, must be successively raised in their lifetime to provide higher storage capacity. Three methods of dam raising can be used: the upstream method, the downstream method and the centerline method. The upstream method, discussed in this thesis, begins with the construction of a starting dyke. After this step, the tailings are deposited upstream, forming a beach which will consolidate over time, gradually increasing the shear resistance of the waste and serving as a foundation for future raising dikes. This procedure continues until the final dam elevation is reached. This method is of simple construction and low cost, but its main disadvantage is that the raising speeds can be excessive and they may induce static liquefaction, a major cause of failure of tailing dams around the world. This dissertation investigates the liquefaction potential of a copper tailing dam, situated in Peru, making use of the empirical method proposed by Olson, based on correlations with data from SPT field tests, and the finite element method, considering the elastoplastic constitutive model UBCSand.

abstract: The continued reliance on fossil fuel for energy resources has proven to be unsustainable, leading to depletion of world reserves and emission of greenhouse gases during their combustion. Therefore, research initiatives to develop potentially carbon-neutral biofuels were given the highest importance. Hydrothermal liquefaction (HTL, a thermochemical conversion process) of microalgae is recognized as a favorable and efficient technique to produce liquid biofuels from wet feedstocks. In this work, three different microalgae (Kirchneriella sp., Galdieria sulphuraria, Micractinium sp.) grown and harvested at Arizona State University were hydrothermally liquefied to optimize their process conditions under different temperatures (200-375 °C), residence times (15-60 min), solids loadings (10-20 wt.%), and process pressures (9-24 MPa). A one-factor-at-a-time approach was employed, and comprehensive experiments were conducted at 10 % solid loadings and a residence time of 30 min. Co-liquefaction of Salicornia bigelovii Torr. (SL), Swine manure (SM) with Cyanidioschyzon merolae (CM) was tested for the presence of synergy. A positive synergistic effect was observed during the co-liquefaction of biomasses, where the experimental yield (32.95 wt.%) of biocrude oil was higher than the expected value (29.23 wt.% ). Co-liquefaction also led to an increase in the energy content of the co-liquefied biocrude oil and a higher energy recovery rate ( 88.55 %). The HTL biocrude was measured for energy content, elemental, and chemical composition using GC-MS. HTL aqueous phase was analyzed for potential co-products by spectrophotometric techniques and is rich in soluble carbohydrates, dissolved ammoniacal nitrogen, and phosphates. HTL biochar was studied for its nutrient content (nitrogen and phosphorous) and viability of its recovery to cultivate algae without any inhibition using the nutrient leaching. HTL biochar was also studied to produce hydrogen via pyrolysis using a membrane reactor at 500 °C, 1 atm, for 24 h to produce 5.93 wt.% gas. The gaseous product contains 45.7 mol % H2, 44.05 ml % CH4, and 10.25 mol % of CO. The versatile applications of HTL biochar were proposed from a detailed physicochemical characterization. The metal impurities in the algae, bio-oil, and biochar were quantified by ICP-OES where algae and biochar contain a large proportion of phosphorous and magnesium. / Dissertation/Thesis / Doctoral Dissertation Chemical Engineering 2020