Thesis (Ph.D)--Murdoch University, 2004. / Thesis submitted to the Division of Science and Engineering. Includes bibliographical references (leaves 136-144).

Thesis (M.Sc.)--Victoria University of Wellington, 2005. / Includes bibliographical references.

The exposed shear zone within the footwall of the Badwater turtleback presents an excellent opportunity to explore the brittle-ductile transition. Within this shear zone, a variety of lithologies preserve the last stages of crystal-plastic deformation concurrent with exhumation of the turtleback. The included field study captures a snapshot of each lithologic element during the last stages of ductile deformation. The exposed shear zone's journey through the brittle-ductile transition is analyzed using the deformation mechanisms of calcite and quartz. A history of strain partitioning is constructed through comparison of the strain and temperature environments needed to facilitate each mechanism of crystal-plastic deformation. As the shear zone cooled, strain was partitioned from quartz-rich mylonitic gneiss to the calcite-dominated marbles and mylonites. Correlation of deformation temperatures with previous studies further constrains the timing of the last stage of ductile deformation to between 13 and 6 Ma.

abstract: ABSTRACT Enzyme-Induced Carbonate Precipitation (EICP) using a plant-derived form of the urease enzyme to induce the precipitation of calcium carbonate (CaCO3) shows promise as a method of stabilizing soil for the mitigation of fugitive dust. Fugitive dust is a significant problem in Arizona, particularly in Maricopa County. Maricopa County is an EPA air quality non-attainment zone, due primarily to fugitive dust, which presents a significant health risk to local residents. Conventional methods for fugitive dust control, including the application of water, are either ineffective in arid climates, very expensive, or limited to short term stabilization. Due to these limitations, engineers are searching for new and more effective ways to stabilize the soil and reduce wind erosion. EICP employs urea hydrolysis, a process in which carbonate precipitation is catalyzed by the urease enzyme, a widely occurring protein found in many plants and microorganisms. Wind tunnel experiments were conducted in the ASU/NASA Planetary Wind Tunnel to evaluate the use of EICP as a means to stabilize soil against fugitive dust emission. Three different soils were tested, including a native Arizona silty-sand, a uniform fine to medium grained silica sand, and mine tailings from a mine in southern Arizona. The test soil was loosely placed in specimen container and the surface was sprayed with an aqueous solution containing urea, calcium chloride, and urease enzyme. After a short period of time to allow for CaCO3 precipitation, the specimens were tested in the wind tunnel. The completed tests show that EICP can increase the detachment velocity compared to bare or wetted soil and thus holds promise as a means of mitigating fugitive dust emissions. / Dissertation/Thesis / M.S. Civil and Environmental Engineering 2014

Diferentes estratégias de flotação (reagentes, pH e rota) têm sido utilizadas na separação entre apatita e carbonatos em todo o mundo. Há evidências na literatura de que a cristalinidade afeta a flotação de apatitas e calcitas com oleato de sódio. Além disso, a dissolução dos sais semi-solúveis pode influenciar a interação entre a superfície dos minerais e os reagentes de flotação, uma vez que o mecanismo de adsorção mais importante é a precipitação de oleato de cálcio na interface sólido/líquido. Portanto, o objetivo deste trabalho é investigar a relação entre cristalinidade, cinética de dissolução e resposta à flotação de apatitas e calcitas de diferentes gêneses (ígnea, metamórfica e sedimentar) e origens. Quatro tipos de minerais foram utilizados: purificados a partir de minérios, previamente purificados, naturalmente puros e amostras de coleção. As amostras foram caracterizadas por fluorescência de raios-X e microanálise (WDS/EDS). Características físicas como densidade (d), área superficial (S) e porosidade (P) também foram determinadas. O método de Rietveld aplicado à difração de raios-X foi usado tanto para comprovar a pureza das amostras como para estudar a cristalinidade dos minerais por meio da determinação dos parâmetros de rede (distâncias a e c, e volume da cela unitária- VCU), além do grau de cristalinidade (GC), tamanho de cristalito (TC) e microdeformação (MD). Ensaios de dissolução, conduzidos na ausência de CO2, forneceram a quantidade (mol) de íons Ca2+ (nCa2+) dissolvidos em função do tempo (t) e normalizada em relação à área superficial. Os resultados se ajustam a um modelo de primeira ordem: nCa2+ = Ca2+MAX(1- e-kt). Este procedimento permitiu calcular os valores da quantidade máxima de íons Ca2+ dissolvidos (Ca2+MAX), bem como da constante cinética (k). Além disso, a velocidade de dissolução foi determinada para a etapa rápida (VR), que caracteriza o início da reação, e para a etapa lenta (VL), que ocorre nas proximidades do estado estacionário. A resposta à flotação com oleato de sódio foi determinada por meio de experimentos de microflotação. Várias relações de causa e efeito são encontradas: flotabilidade (F) versus VR, e VR versus características intrínsecas (parâmetros de rede, de cristalinidade e físicos). VR foi selecionado para participar de tais modelos, pois, caracteriza o intervalo de tempo em que o condicionamento (1 minuto) e a microflotação (1 minuto) ocorrem. Observa-se que a flotabilidade dos minerais aumenta com o aumento de VR, sugerindo que apatitas e calcitas que disponibilizam mais íons Ca2+ em solução para interagir com o oleato, exibem mais elevada flotabilidade. Equações lineares de F em função de VR em pH 8 (R = 0,97 para apatitas e R = 0,66 para calcitas) e pH 10 (R = 0,95 para apatitas e R = 0,63 para calcitas) foram encontradas. Correlações lineares múltiplas foram utilizadas para relacionar VR (em pH 8 e 10) com as características intrínsecas que exercem maior influência sobre este parâmetro. Para as apatitas, VR foi equacionado em função de GC, TC e c, enquanto para as calcitas, os parâmetros GC, TC, d e P foram selecionados para compor o modelo. Os valores de VR calculados se ajustam aos observados dentro de um intervalo de confiança de 95%. As equações lineares propostas para as apatitas foram usadas para se estimar F das amostras de Anitápolis-SC e Tapira-MG, que não foram submetidas aos ensaios de dissolução. Os valores de F calculados estão em concordância com aqueles experimentalmente determinados. / Different flotation strategies (reagents, pH and route) have been adopted to separate apatite from carbonates around the world. Literature provides evidences that crystallinity affects flotation response of apatite and calcite with sodium oleate. Furthermore, dissolution of salt-type minerals influences the interaction between mineral surface and flotation reagents, because the most important adsorption mechanism is the surface precipitation of calcium oleate onto mineral/water interface. Therefore, the objective of this research is to investigate the relationship between crystallinity, dissolution kinetics and flotation response of apatites and calcites from different genesis (igneous, metamorphic and sedimentary) and origins. Four sorts of minerals were utilized: minerals purified from ores, minerals previously purified, naturally pure minerals and collection samples. They were characterized by X-ray fluorescence and X-ray microanalysis (WDS/EDS). Physical characteristics, as specific gravity (d), surface area (S) and porosity (P), were also determined. The Rietveld method applied to X-ray diffraction data was used either to probe the purity of samples or to study the crystallinity of the minerals by means of determining their lattice parameters (a and c dimensions plus lattice volume-VCU), in addition to crystallinity degree (GC), crystallite size (TC) and microstrain (MD). Dissolution experiments, conducted in the absence of CO2, yielded curves which relate the amount (mol) of dissolved Ca2+ ions (nCa2+) versus time (t), normalized by the surface area. They fit a first order model: nCa2+ = Ca2+MAX(1- e-kt). Curve fitting via exponential adjustment was accomplished to calculate values of the maximum amount of dissolved Ca2+ ions (Ca2+MAX) and the kinetic constant (k). In addition, the dissolution rate was determined for the fast step (VR), which characterizes the beginning of the reaction, and for the slow step (VL), as it tends to the steady state. Flotation response with sodium oleate was determined by microflotation experiments. Several cause-effect relationships are found: floatability (F) versus VR, and VR versus intrinsic characteristics of minerals (lattice, crystallinity and physical parameters). VR was selected to participate in the model because it characterizes the length of time along which reagent conditioning (1 minute) plus microflotation (1 minute) take place. It is observed that F increases as VR becomes greater, suggesting that samples of apatites and calcites which place more Ca2+ ions in solution to interact with oleate exhibit higher flotation performance. Linear equations of F versus VR at pH 8 (R = 0,97 for apatites and R = 0,66 for calcites) and pH 10 (R = 0,95 for apatites and R = 0,63 for calcites) were found. Likewise, multiple linear correlations were used to relate VR (at pH 8 and 10) with the intrinsic characteristics of apatites and calcites that affect VR to a greater extent. For apatites, VR was modeled as a function of GC, TC and c, while for calcites, the parameters GC, TC d and P were selected to compose the model. The calculated VR values fit the experimental ones within 95% of confidence. The linear equations developed for apatites were used to estimate floatability of the samples from Anitápolis-SC and Tapira-MG, which were not submitted to dissolution experiments. The values of calculated floatability are in agreement with the experimental ones.

A detailed understanding of fundamental material properties can be obtained through the study of atomic vibrations, performed experimentally with neutron scattering techniques and coupled with the two powerful new computational methodologies I have developed. The first approach involves phonon-based simulations of the pair distribution function - a histogram of localised atomic positions generated experimentally from total scattering data. This is used to reveal ordering behaviour, to validate interatomic models and localised structure, and to give insights into how far dynamic behaviour can be studied using total scattering techniques. Most importantly, the long-standing controversy over dynamic disorder in β-cristobalite is resolved using this technique. Inelastic neutron spectroscopy (INS) allows \emph{direct} study of vibrational modes through their interaction with the neutron beam, and is the experimental basis for the second strand of the new methodology. I have developed new simulation and refinement tools based on the next generation of spectrometers currently being commissioned at the ISIS pulsed neutron source. This allows a detailed powder spectroscopy study of cristobalite and vitreous silica demonstrating that the Bose peak and so-called 'fast sound' features can be derived from standard lattice dynamics in both the crystal and the amorphous counterpart, and allowing discussion of their origins. Given the controversy in the literature, this is a key result. The new methodology also encompasses refinement of interatomic models against powder INS data, with aluminium providing a successful test-case. A more complex example is seen in calcite, with experimental data collected during the commissioning of the new MERLIN spectrometer. Simulated one-phonon coherent INS spectra for the single crystal and powder (the latter including approximations to multi-phonon and multiple scatter) are fully convolved with experimental resolution functions. These are used in the analysis of the experimental data, yielding previously unpublished dispersion curves and soft mode information, as well as allowing the effectiveness of powder refinement of more complex materials to be assessed. Finally, I present further applications with technologically important materials - relaxor ferroelectrics and high temperature pnictide superconductors. The conclusions draw together the different strands of the work, discussing the importance of these new advances together with future developments and scientific applications.

Leachate clogging in the Leachate Collection System (LCS) due to chemical precipitations and biofilms produced by microbial activities is a common phenomenon in any Municipal Solid Waste (MSW) landfill. This study focuses on quantifying the factors that impact the micro-environment of leachate; and microbial activities that help the precipitates to form and attach to the LCS. It also evaluates the performance of operational changes that have been implemented or the potential alternatives and recommends the possible measures to reduce the severity of clogging. A field scale side-by-side pipe network, and several laboratory setups were used in this study. Calcite is identified to be the predominant phase present in the precipitates using XRD/XRF analysis which, concur with the previous studies. Microbial growth and activities enhance the precipitation of CaCO3 in LCS. Clogging in LCS pipes can be controlled if not eliminated by continuous monitoring along with frequent cleaning with physiochemical processes. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

The precipitation system CIPS (Calcite In-situ Precipitation System) has been created as a permeation grouting system based on a two component fluid with the intention of slowly permeate and fill the pores. It causes cementation through a chemical reaction which bonds the soil particles together at the contact points. CIPS mimics one of the natural reactions in nature where sandstone is formed through calcite precipitation. This system is used in Australia with excellent results and there are many factors governing the outcome of the method, some of these factors are: flow rate, pressure, time, chemical recipe, temperature, composition of the soil matrix and number of performed injections at the same point of location. Some of these factors have been the focus of this report and where they have been examined from a Scandinavian point of view where our ground temperature conditions and soil compositions have governed the outcome of the accomplished results. The strength increase has been examined through laboratory tests where natural sand from a building site with known particle size and dry density has been treated once with the CIPS Fluid. This treatment was completed in a temperature controlled room of 12 degrees after which the treated soil was tested by unconfined compression tests. Even a rather low increase in bearing capacity of the soil would result in benefits during the construction of temporary constructions during the early building stages foundation work. Since the desired increase in bearing capacity of the soil is fairly low, 50-100 kPa, the investigations has concentrated on one single injection, in order to study if there is a clear trend in the increase in bearing capacity, and if it can be roughly predicted. In addition to the above mentioned laboratory work a small scale field test has been conducted, where the CIPS Fluid was injected into the ground with the aim of creating a column shaped object. This column was left for a certain time, a time long enough for the calcite crystal to bond the soil grains and generate an increase in strength. When the assumed cementation had occurred an ocular assessment was carried out in order to predict whether the strength had increased or not, and to what degree. Based on the laboratory results, some evidence of that strength increase occurs due to either the discharge of the spent fluid containing ammonium chloride or the process of drying. Either way, the strength increase takes place during the grounds natural process of adjusting towards the natural water content equilibrium for the specific site of interest. A strength increase at the laboratory experiments of between approximately 60-220 kPa has been achieved. The field tests where slightly less rewarding when difficulties of injecting the CIPS Fluid into the sandy soil arose due to challenging task of designing a pumping system where both a low pressure, less than the overburden pressure, and a low flow rate, less than 7 litres per minute, could be controlled. The flow rate could be controlled but with the effect of the pressure rising to too high levels. Due to the observations of CIPS Fluids exiting the ground at other points than near the injection spear, soil fractures are assumed to have occurred at one ore many locations. The volumes treated with CIPS Fluid displayed no increase in strength as long as they appeared somewhat wet with the spent fluid. When this fluid containing ammonium chloride vanished from the treated soil and the pH-value dropped, the build up in strength through calcite crystallisation at the contact points began. This crystallization which leads to a cementation was observed at the centre of the small spheres achieved through injection in the ground, which proves that the Calcite In-situ Precipitation System has caused a cementation of the soil grains treated.

The subsumed work of this dissertation is comprised of three independent but interrelated studies which seek to further the understanding of processes which govern the coprecipitation of trace elements with calcite and aragonite minerals. These studies investigate the effects of: 1) pressure on crystal morphology and trace element incorporation to aragonite; 2) growth rate on uranium partitioning between calcite and fluid; 3) aqueous Mg/Ca on the magnesium partitioning to low-magnesium calcite. The importance of this work is to determine how the environment of formation and growth rate influences the geochemistry of CaCO3 in order to improve existing paleoproxies and develop new ones. In the first study a series of experiments were conducted at 1, 25, 75, 100, and 345 bars of nitrogen – this range covers pressures at the oceanic floor. Aragonite precipitation was induced by the one-time addition of a Na2CO3 solution to an artificial seawater. Results suggest that oceanic floor pressures could affect the crystallization of CaCO3 by altering mineralogical composition and aragonite crystal size. In the second study calcite crystallized from NH4Cl-CaCl2-U solution by diffusion of CO2. The calcite growth rate was monitored by sequential spiking of the calcite-precipitating fluids with REE dopants. The resulting crystals were analyzed using Secondary Ion Mass Spectrometry (SIMS). Results showed that the partitioning of uranium increases with increasing growth rate. Growth entrapment model (GEM) and unified uptake kinetics model (UUKM) explain the obtained data.In the third study CaCO3 precipitated in NaCl solution by continuous addition of CaCl2, MgCl2, and either Na2CO3 or NaHCO3. The Mg/Ca of the fluid was adjusted in an attempt to produce calcite where Mg/Ca would match Mg/Ca in foraminifera shells. It was observed that multiple CaCO3 polymorphs precipitated from fluids at high pH (Na2CO3 doping experiments). This result underscores the potential control of pH and/or supersaturation state on CaCO3 polymorph precipitated from low Mg/Ca solutions. Calcite was the only mineral crystallized at low pH (NaHCO3 doping experiments). It was determined that Mg partition coefficient between calcite and fluid (KMg) negatively correlates with Mg/Ca(Fluid) when it exceeds 0.5 mol/mol; no systematic correlation was observed when 0.05< Mg/Ca(Fluid)<0.5 mol/mol.

Fluid-rock interaction causes an exchange of isotopes or elements through various reactions. The rate of these reactions strongly depends on temperature. The interaction involves dissolution precipitation, chemical exchange reactions, redox reactions, diffusion, and their combinations. The goal of studying fluid-rock interaction is to understand the change in mineral chemistry of the rock materials when in contact with an aqueous solution. These processes occur in all regions of the Earth where aqueous solutions are found. This work is comprised of three independent studies which provide an understanding about crystallization processes under multiple hydrothermal conditions with geological and environmental applications. In the chapter 1, subsurface rock and CO2-saturated brine reactions were evaluated under laboratory hydrothermal conditions when injected carbon dioxide is in contact with sedimentary strata at a planned sequestration sites at Kemper County Mississippi. Five rock samples were taken from different depths using core cuttings for experimentation. The results reveal no reaction of clay particles and CO2-rich fluid; in contrast, in samples from the depth of the unconformity, significant formation of secondary minerals occurred by reaction with the rock sample at the unconformity. The second study focuses on the incorporation of uranium (VI) into the crystal lattice of calcite at hydrothermal conditions. This study was designed to understand uranium (VI) behaviors in a calcite-fluid system at elevated temperatures due to decay of radioactive waste from nuclear power plants. The results showed uranyl hydroxide formation was preferred at hydrothermal conditions, 120 – 350 oC. The incorporation of U6+ in calcite lattices was evaluated, though the data showed a limited amount of U6+ entrapment. The third study focuses on quantification of the retention of Mg/Ca, Sr/Ca, and d18O during the aragonite-calcite transformation process as well as evaluation of the transformation rate. The results show partial retention of Mg and Sr during aragonite transformation to calcite in Mg-, Sr-free solutions, but no retention of d18O. Aragonite oxygen isotope composition was erased during mineral transformation because fractionation was controlled by temperature and the d18O of the bulk solution.