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Preliminary Investigations of CaCO3 Nucleation in Precipitation Reactions from Quasi-Homogeneous SolutionDuranza, Francis Cristian 11 1900 (has links)
<p> An analysis of reported and theoretical methods of precipitating calcium carbonate from aqueous solution is presented, with emphasis on methods that generate the anion in the presence of Ca(++) ion.</p> <p> A new CaCO3 precipitation method referred to as precipitation from quasi-homogeneous solution and suitable for digital processor control is developed. This technique is then used to investigate the effects of ionic strength and Mg(++) ion on calcium carbonate nucleation.</p> <p> A minicomputer based interactive information system, capable of automatic data logging and processing of experimental results in studies using processor controlled precipitation of CaCO3 from quasi-homogeneous solution, is implemented and tested.</p> / Thesis / Master of Science (MSc)
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Ore Petrography, Carbonate Alteration and Geochemistry of the McBean Mine, Larder Lake, OntarioBell, Cameron 04 1900 (has links)
<p> The McBean Mine is a small gold producer located along
the Larder Lake Break. Ore from the open pit consists of
massive and gneissic syenite. The highest go I d grades come
from highly carbonitized syenitic rocks with abundant fine
grained, euhedral pyrite. Petrographic observation shows
gold to be found as inclusions in pyrite, platings on pyrite
and as free grains in the gangue. XRD analyses show the
major carbonate type to be dolomite. In addition to
dolomite, minor amounts of calcite are found in auriferous
syenitic rocks. SEM microscopy shows carbonate composition
to vary with rock types and grain location. Geochemical
studies show a high intensity of carbonate alteration and the
association of gold with tungsten and uranium. Auriferous
syenites were determined to have elevated HREE element
abundances compared with unaltered syenite. The mine is
therefore characterized by extensive hydrothermal carbonate
alteration related to the Larder Lake Break. </p> / Thesis / Bachelor of Science (BSc)
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Syntetiskt pärlemor : Producerat via in situ-kristallisation / Synthetic nacre : Produced by in situ crystallisationBlomberg, Pontus January 2023 (has links)
This thesis describes a sequence of experiments which have been performed with the intention to produce synthetic nacre. Synthetic nacre is a biomimetic material based on nacre, a material which can be found in mollusc shells. Nacre is a nanocomposite which has improved mechanical properties compared to the principal component aragonite (95% wt%). The improved properties of nacre are derived from the polymeric components in the composite which allows from redistribution of forces under load. Carbonates sequester CO2 in the geological CO2-cycle. If precursor are sourced correctly, the CaCO3 in synthetic nacre can temporarily sequester CO2. Crystals with the intended pseudohexagonal morphology have been synthesised. However, subsequent quantitative analysis could not support these findings in a follow-up experiment. This discrepancy might have been caused by differences in the method. Moist nanopaper was found to be mineralisable while maintaining a layered structure.
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Mitigating the shrink-swell capacities of the Yazoo Clay through application of lime and biocharBrister, Austin Alan 09 December 2022 (has links)
Shrinking and swelling in Yazoo Clay is a cause of concern for construction projects in Mississippi. This thesis investigated the effects of adding lime and Douglas Fir biochar on the shrinking and swelling capabilities of Yazoo Clay. Samples of Yazoo Clay were mixed with the additives in defined ratios and subjected to the free swell test and the COLE(rod) test. Biochar addition reduced the COLE(rod) of the samples a large amount, while increasing the swelling potential of the clay samples. The addition of lime slightly reduced both the shrinking and swelling potentials of the samples. The mineralogical variability of Yazoo Clay vertically and horizontally could limit the applicability of these results across the formation and is important to be considered before further application. While constrained to one location, this study showed the influence of biochar and lime on the shrinking and swelling capabilities of Yazoo Clay.
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Stable Amorphous Calcium Carbonate: Crystallization Behaviour and Stable IsotopesAllan, Katherine January 2022 (has links)
Abstract
Amorphous Calcium Carbonate (ACC) is a naturally occurring amorphous form of the widely distributed mineral calcium carbonate (CaCO3). ACC has been found increasingly as a precursor phase, calcium storage site, or strengthening structural phase in a wide array of different biomineralizing organisms. An accurate understanding of the widely used classic carbonate-water paleothermometry relies on formation of CaCO3 minerals and associated oxygen isotope effects. Moreover, ACC has oft been pointed to as a possible reason for non-equilibrium isotope effects, also called vital effects, in biogenic carbonates. It is, therefore, vital to understand whether ACC can reach equilibrium with its surrounding solution, as well as the role of ACC precursors in the isotopic composition and evolution of the final crystalline phase they transform into. This study is designed to answer these questions through the precipitation of stable ACC by two methods, the alkaline method (AM) which utilizes high pH to precipitate ACC, and the silica method (SM) which envelopes precipitating ACC particles in silica vesicles to prevent crystallization. These differently precipitated ACCs are then subjected to several different experimental treatments. This is achieved by monitoring the crystallization by X-ray Diffraction (XRD), and isotopic evolution of the ACC precipitates by Isotope Ratio Mass Spectrometry (IRMS) as they age and concurrently crystallize in parent solution, or in 18O enriched re-equilibration solution.
This research indicated a marked difference in the crystallization behaviour, isotopic composition, and isotopic evolution of ACC produced by these two precipitation methods. With the AM method, ACC precipitates (AM-ACC) crystallized more predictably to calcite and maintained δ18O signatures that were slightly lower than the equilibrium CO32- and resisted further isotopic exchange with surrounding solution. We propose that the former is mostly due to an incomplete DIC-water oxygen isotope equilibrium prior to the AM-ACC precipitation and the latter is a result of the high pH of the precipitating solution decreasing the solubility of the precipitated ACC phase, disallowing isotope exchange, and favouring crystallization by solid-state transformation. Conversely, while ACC precipitated using the SM (SM-ACC) yielded much more variable results, both in terms of mineralogical identity upon crystallization, and δ18O values. Isotopic results were much closer to the expected equilibrium δ18O value for calcite, hinting at an expedited oxygen isotope exchange between SM-ACC and parent solution. Furthermore, SM-ACC was capable of isotopic exchange with the 18O enriched re-equilibration solution, a feat corresponding AM-ACC was incapable of. Overall, our experimental results gleaned here that precipitation method or precipitation environment play a critical role in the isotopic evolution of precursor ACC to crystalline CaCO3, suggesting ACC as an important source of the vital effect. / Thesis / Master of Science (MSc)
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Structural Controls on Megaporosity in Eogenetic Carbonate Rocks: Tinian, CNMIStafford, Kevin Wayne 13 December 2003 (has links)
Tinian and Aguijan, Commonwealth of the Northern Mariana Islands (CNMI), are volcanic, back arc islands in the western Pacific formed by Pacific Plate subduction under the Philippine Plate. The islands are composed of Eocene volcanic cores mantled by Plio-Pleistocene carbonate facies and raised Holocene beach and reef deposits. The entire sequence has been tectonically uplifted and contains high-angle normal faults, while isostatic subsidence and scarp failures overprint tectonic brittle failure features. A cave and karst inventory on Tinian and Aguijan surveyed 114 features and is believed to adequately represent the megaporosity (cave) development. Two distinct cave classes were identified: mixing zone caves (flank margin caves and banana holes) and fissure caves. Most mixing zone caves were located in or near scarps and coastlines, often at similar elevations to nearby caves. Fissure caves were located in regions of brittle failure, forming linear features with narrow widths. Three previous sea-level positions were identified based on horizons of mixing zone caves. Seventeen freshwater discharge sites and four allogenic recharge sites were identified on Tinian. Kolmogorov-Smirnov statistical analyses and rose diagram comparisons of orientation trends found significant similarities between megaporosity and geologic structure (brittle failure) on Tinian. Analyses of small regions showed distinct relations between brittle deformation and megaporosity, while at larger scales similarities became less obvious due to the complex geologic history and physiography of the island. Based on similarities in populations of orientation trends, fissure cave development is primarily controlled by brittle failure deformation with development along faults, fractures, and joints, while mixing zone cave development is primarily controlled by fresh-water lens position but significantly influenced by brittle failure deformation. Tinian and Aguijan do not fit neatly into one classification of the Carbonate Island Karst Model. Regions of Tinian best fit the Simple, Carbonate-Cover and Composite Island Karst Models, but none easily fit the entire island. Aguijan must be classified as a Simple Carbonate Island because no geologic data has proved the presence of non-carbonate rocks interfering with the fresh-water lens, however it is probable that Aguijan does contain basement rocks that extend above sea-level as on other carbonate islands in the Marianas.
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GEOCHEMICAL AND STABLE ISOTOPIC EVALUATION OF FENGHUOSHAN GROUP LACUSTRINE CARBONATES, NORTH-CENTRAL TIBET: IMPLICATIONS FOR THE PALEOALTIMETRY OF THE MID-TERTIARY TIBETAN PLATEAUCyr, Andrew J. 01 April 2004 (has links)
No description available.
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The Evaluation of the Hindered Settling Behavior of the Ground Calcium Carbonate SuspensionJain, Raj R. 22 July 2014 (has links)
No description available.
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The effects of grain size on the strength of magnesite aggregates deforming by low temperature plasticity and diffusion creepMcDaniel, Caleb Alan 26 July 2018 (has links)
No description available.
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EARLY MISSISSIPPIAN CARBONATE BUILDUPS IN SOUTHERN KENTUCKY, USA: PALEOECOLOGIC AND SEQUENCE STRATIGRAPHIC INTERPRETATIONSKRAUSE, RICHARD ALAN 24 September 2002 (has links)
No description available.
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