Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The spodumene (LiAlSi2O6 - LAS) is a silicate that has shown good results for high-dose dosimetry for gamma rays. This silicate may be obtained naturally or synthetically. The synthetic spodumene has been produced by solid state reaction, whose difficulty arises from the need to employ high temperatures. This paper aims to produce LAS through two different production routes: the proteic sol-gel and Pechini methods. The material produced was characterized by X-ray diffraction (XRD), differential thermal analysis (DTA) and thermogravimetry (TGA) in order to evaluate the structural properties of the material, as well as possible changes in physical or chemical properties depending on the temperature. It was found by XRD and Rietveld refinement was possible to obtain LAS B-spodumene phase by both methods. The thermal analysis showed that the material for both methods suffer considerable loss of weight in the temperature range 20-600 °C. Through thermoluminescent measures, one can observe that the LAS produced by both methods shows thermoluminescent peaks from beta irradiation at a dose of 1 Gy, thus allowing its application dosimetry. It can be concluded therefore that there is the possibility of producing them in large numbers at reduced cost and environmental impact, being viable in dosimetry. It also follows that the sol-gel protein appeared to be the best way to produce the LAS compared with other routes used, such as solid state synthesis or devitrification. / O espodumênio (LiAlSi2O6 LAS) é um silicato que tem demonstrado bons resultados para dosimetria de altas doses para raios gama. Esse silicato pode ser obtido de forma natural ou sintética. O espodumênio sintético tem sido produzido por reação do estado sólido, cuja dificuldade provém da necessidade de se empregar altas temperaturas. O presente trabalho tem o objetivo de produzir o LAS por meio de duas rotas de produção diferentes: a sol-gel proteica e método Pechini. O material produzido foi caracterizado através da difração de raios X (DRX), análises térmica diferencial (DTA) e termogravimétrica (TGA) com o intuito de avaliar as propriedades estruturais do material, bem como as possíveis mudanças de propriedades físicas ou químicas em função da temperatura. Verificou-se através da DRX e do refinamento Rietveld que foi possível se obter LAS na fase B-espodumênio por ambos os métodos. As análises térmicas mostraram que o material, por ambos os métodos, sofre perda considerável de massa no intervalo de temperatura de 20 a 600 °C. Através de medidas termoluminescentes, pode-se observar que o LAS produzido por ambos os métodos apresenta picos termoluminescentes a partir de irradiação beta com dose de 1 Gy, possibilitando sua aplicação dosimétrica. Pode-se concluir, assim, que há possibilidade de produção do LAS em larga escala a um custo e impacto ambiental reduzidos, sendo viável sua utilização em dosimetria. Também se conclui que o método sol-gel proteico se apresentou como sendo a melhor forma de produzir o LAS em comparação com outras rotas utilizadas, tais como síntese de estado sólido ou desvitrificação.

Lithium represents one of the strategic elements for the rest of the 21st century due to its increasing demand in technological applications. Therefore, new efforts should be focused on the optimization of mineral characterization processes, which link the ore properties with its behaviour during downstream processes. These efforts should result in reducing operational risks and increasing resources utilization. The methodology presented in this study is based on the application of several classification techniques, aiming the mineral and textural characterization of two spodumene pegmatite deposits within the Keliber Lithium Project. Twelve textural classes have been proposed for the textual classification of the ore, which have been defined through the recognition of the main mineral features at macro- and micro-scale. The textural classification was performed through the application of drill core logging and scanning electron microscopy. Six classes are proposed to describe the characteristics of the spodumene ore. Six additional classes describe the main properties of the rocks surrounding the ore zone. Image analysis was implemented for the generation of mineral maps and the subsequent quantification of spodumene and Li2O within the analysed drill core images. The image segmentation process was executed in Fiji-ImageJ and is based on eight mineral classes and a set of seven feature extraction procedures. Thus, quantification of spodumene and Li2O is estimated by textural class. Hyperspectral images were used as a reference for assessing the estimations made through images analysis. A machine learning model in Weka allowed forecasting the behaviour of the twelve textural classes during spodumene flotation. This model is fed by metallurgical data from previous flotation tests and uses Random Forest classifier. The proposed methodology serves as an inexpensive but powerful approach for the complete textural characterization of the ore at Keliber Lithium Project. It provides information about: (1) mineral features at different scales, (2) spatial distribution of textures within the pegmatite body, (3) quantification of spodumene and Li2O within the drill cores and (4) processing response of each textural class. However, its application requires wide knowledge and expertise in the mineralogy of the studied deposits. / <p>Thesis Presentation.</p><p>Textural and Mineralogical Characterization of Li-pegmatite Deposit: Using Microanalytical and Image Analysis to Link Micro and Macro Properties of Spodumene in Drill Cores.  Keliber Lithium Project, Finland.</p><p></p>