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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

IR spectroscopy of planetary regolith analogues, lunar meteorites, and Apollo soils

Martin, Dayl January 2018 (has links)
The main objectives of this study are to determine how various physical and chemical properties of geologic samples can be investigated by Fourier Transform InfraRed (FTIR) spectral analyses, and determine how each of these individual properties uniquely alter the mid-infrared spectrum. Of particular interest is how extraterrestrial samples differ (spectrally) from terrestrial samples, and how such findings can be applied to current and future missions to airless planetary bodies (such as Diviner Lunar Radiometer, aboard the Lunar Reconnaissance Orbiter, and the Mercury Thermal Radiometer on BepiColombo). As such, a range of geological samples have been analysed including terrestrial rocks (anorthosite, granite, grabbro etc.), mineral standards (common rock-forming minerals), lunar meteorites (from Miller Range, Antarctica), and Apollo 14, 15, and 16 soils. A new technique to analyse such samples has been developed and implemented as part of this study: FTIR spectral imaging of unconsolidated samples (powders and soils) to obtain modal mineralogy estimates. Such estimates are comparable to QEMSCAN analyses and spot point counting of the same samples. This is particularly relevant for the non-destructive analysis of Apollo soil samples (bulk and sieved fractions). Individual spectra of polished terrestrial and extraterrestrial samples have been obtained in preparation for the creation of a spectral database. Such samples also have coupled chemical composition information via Electron Probe MicroAnalysis (EPMA). To have a spectrum and an associated chemical composition for each mineral in a database is unique compared to other spectral databases. Analyses of lunar meteorites resulted in an understanding of how shock (caused by hypervelocity impacts) alters the physical and spectral properties of lunar minerals. FTIR microscopy of individual minerals and phases in the meteorites were coupled with optical and cathodoluminescence (CL) imaging to identify the level of shock obtained by each mineral and phase. The FTIR reflectance bands of plagioclase merge with increasing shock pressure until a single, low-reflectance broad peak is displayed by the most highly shocked plagioclase (>45 GPa), and a dark-red colour is present in CL images. FTIR and QEMSCAN analyses of Apollo regolith samples have provided an understanding of the spectral effects of bulk mineralogy, maturity (a measure of the time spent at the lunar surface), grain size, and mineral chemistry. Using such information, the modal mineralogy of each sample has been estimated, one of which had not previously been analysed for its modal mineralogy. Samples from the same Apollo missions present similar spectral features, meaning FTIR spectroscopy can be used to identify the origin of lunar soils. A weak correlation in maturity with a spectral feature termed the Christiansen Feature has been found for lunar samples. Related to maturity, FTIR spectra of individual agglutinates (a product of space weathering) have been obtained and the spectral properties of agglutinates (decreased %Reflectance values of the region sensitive to geological materials) resemble those of highly mature lunar soils.
2

Development of a geometallurgical framework for iron ores - A mineralogical approach to particle-based modeling / Utveckling av ett geometallurgiskt ramverk för järnmalmer - Ett mineralogiskt angreppssätt till partikelbaserad modellering.

Parian, Mehdi January 2017 (has links)
The demands for efficient utilization of ore bodies and proper risk management in the mining industry have resulted in a new cross-disciplinary subject called geometallurgy. Geometallurgy connects geological, mineral processing and subsequent downstream processing information together to provide a comprehensive model to be used in production planning and management. A geometallurgical program is an industrial application of geometallurgy. Various approaches that are employed in geometallurgical programs include the traditional way, which uses chemical elements, the proxy method, which applies small-scale tests, and the mineralogical approach using mineralogy or the combination of those. The mineralogical approach provides the most comprehensive and versatile way to treat geometallurgical data. Therefore it was selected as a basis for this study. For the mineralogical approach, quantitative mineralogical information is needed both for the deposit and the process. The geological model must describe the minerals present, give their chemical composition, report their mass proportions (modal composition) in the ore body and describe the ore texture. The process model must be capable of using mineralogical information provided by the geological model to forecast the metallurgical performance of different geological volumes and periods. A literature survey showed that areas, where more development is needed for using the mineralogical approach, are: 1) quick and inexpensive techniques for reliable modal analysis of the ore samples; 2) ore textural characterization of the ore to forecast the liberation distribution of the ore when crushed and ground; 3) unit operation models based on particle properties (at mineral liberation level) and 4) a system capable of handling all this information and transferring it to production model. This study focuses on developing tools in these areas. A number of methods for obtaining mineral grades were evaluated with a focus on geometallurgical applicability, precision, and trueness. A new technique developed called combined method uses both quantitative X-ray powder diffraction with Rietveld refinement and the Element-to-Mineral Conversion method. The method not only delivers the required turnover for geometallurgy but also overcomes the shortcomings if X-ray powder diffraction or Element-to-Mineral Conversion were used alone. Characterization of ore texture before and after breakage provides valuable insights about the fracture pattern in comminution, the population of particles for specific ore texture and their relation to parent ore texture. In the context of the mineralogical approach to geometallurgy, predicting the particle population from ore texture is a critical step to establish an interface between geology and mineral processing. A new method called Association Indicator Matrix developed to assess breakage pattern of ore texture and analyze mineral association. The results of ore texture and particle analysis were used to generate particle population from ore texture by applying particle size distribution and breakage frequencies. The outcome matches well with experimental data specifically for magnetite ore texture. In geometallurgy, process models can be classified based on in which level the ore, i.e. the feed stream to the processing plant and each unit operation, is defined and what information subsequent streams carry. The most comprehensive level of mineral processing models is the particle-based one which includes practically all necessary information on streams for modeling unit operations. Within this study, a particle-based unit operation model was built for wet low-intensity magnetic separation, and existing size classification and grinding models were evaluated to be used in particle level. A property-based model of magnetic beneficiation plant was created based on one of the LKAB operating plants in mineral and particle level and the results were compared. Two different feeds to the plant were used. The results revealed that in the particle level, the process model is more sensitive to changes in feed property than any other levels. Particle level is more capable for process optimization for different geometallurgical domains.

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