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Froth flotation is a separation process by which particles are selectively attached to air bubbles. It is one of the most dynamically complex industrial processes in use today. This complexity has steered research towards understanding the fundamental principles of the process. Relatively few researchers have successfully attempted to create a flotation simulator based on first principles. This thesis presents the development and testing of a simulator called SimuFloat, which is based on the flotation model developed at Virginia Tech. Flotation of chalcopyrite, coal, and phosphate are simulated. These simulations show the effects of changing the input parameters of the flotation circuit. The accuracy of SimuFloat is validated by comparing the predictions with the experimentally obtained flotation results. / Master of Science

Froth flotation is a widely used, cost effective particle separation process. However, its high performance is limited to a narrow particle size range, e.g., between 50 µm and 600 µm for coal and between 10 µm and 100 µm for minerals. Outside this range, the efficiency of froth flotation decreases significantly, especially for difficult-to-float particles of weak hydrophobicity (e.g., oxidized coal). Nanobubbles integrated into a specially designed column flotation expanded the particle size range for efficient froth flotation as a result of increased probabilities of particle- bubble collision and attachment and reduced probability of detachment. The major advantages of nanobubble enhanced flotation include lower collector and frother dosages since nanobubbles that are mostly smaller than 1 µm can be formed selectively on hydrophobic coal particles from dissolved air in coal slurry. Nanobubbles act as a secondary collector on particle surfaces, thereby resulting in considerably lower operating costs. A systematic parametric investigation of the proposed technology was performed to understand the effects of process variables on separation performance with a typical coal sample using a specially designed flotation column and three 10-liters conventional flotation cells. Results indicate that the combustible recovery of a -150 µm coal increased by 5-50% in the presence of nanobubbles, depending on process operating conditions. Nanobubbles also significantly improved process separation efficiency and increased the flotation rate constant by more than 40%. Theoretical evaluation of the innovative flotation technology was employed using specially designed apparatus to study the nanobubbles stability and the roles of nanobubbles on particle-bubble interactions, froth stability, and surface area flux. In addition, a detailed technical performance and economic evaluation was performed.

A bibliometria é um instrumento quantitativo que através de medidas matemáticas e estatísticas permite mapear e gerar informações que auxiliam na tomada de decisões de uma determinada área científica. Verificou-se o evidente crescimento da produção científica na área de flotação de caulinita e da significativa importância desse assunto em meios acadêmicos, realizou-se a necessidade de um estudo de natureza bibliométrica. Este estudo é uma maneira de observar a quantidade do que está sendo produzido, quais são os principais trabalhos desenvolvidos e quais foram os resultados atingidos. O presente trabalho apresenta uma discussão de natureza bibliométrica sobre artigos publicados no mundo, relacionados sobre o assunto flotação de caulinita, em periódicos internacionais no período de 1992 e 2015. Através deste trabalho foi possível reconhecer e identificar quais são as tendências temáticas e metodológicas que estão sendo usadas, além dos principais coletores utilizados na flotação de caulinita. Os resultados mostram que é significativa a quantidade de artigos produzidos por autores chineses, especialmente a partir do ano de 2013, visto ser a China a maior produtora de alumínio no mundo, e a caulinita, é o rejeito no processo de flotação reversa do diásporo. Foram encontrados muitos estudos com propostas e estruturas semelhantes, utilizando métodos que são importantes para compreender os fenômenos físico-químicos na flotação, como: métodos de caracterização mineralógica, potencial zeta, métodos de adsorção e outros. Os artigos analisados tinham uma média de 7 páginas por artigo e todos foram pesquisados no SciVerse ScienceDirect, pertencente à editora Elsevier. Dos 39 artigos analisados, 31 possuem avaliação interdisciplinar da Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) e são classificados no estrato A1, que são artigos de mais alta qualidade. Os resultados mostraram a dificuldade de trabalhar com o tema de flotação de caulinita individualmente e confirmou que existe uma colaboração científica entre autores. No estudo por palavras-chave, (ao todo 180) verificou-se a presença de termos como \"aluminossilicatos\", \"minérios oxidados\" e \"diásporo\" junto com o termo \"caulinita\", além de outras palavras-chave como \"flotação\" e \"adsorção\". Os minerais envolvidos na flotação junto com caulinita também foram avaliados, mineral diásporo aparece frequentemente relacionando com o mineral de interesse dessa dissertação. Na avaliação por citações pelo Scopus, os artigos foram classificados conforme sua importância no meio acadêmico. Além disso, através da análise bibliométrica verificouse que os reagentes utilizados nos testes de flotação de caulinita são de grande maioria derivados de nitrogenados catiônicos. Os valores de pH mais utilizado de flotação ocorreram em meio ácido, embora, muitos coletores apresentem também bons resultados em meio neutro e/ou alcalino. Observou-se também que ainda há muito para ser pesquisado, visto que a maior parte dos artigos amostrados realizam pesquisa em escala laboratorial e não descrevem a realidade das usinas de beneficiamento de caulinita no mundo. / Bibliometrics is a quantitative instrument that, through mathematical and statistical measures, allows to map and generate information that assists in the decision-making of a certain scientific area. In the area of kaolinite flotation, a clear growth of scientific production and a significant importance of this subject in academic areas were noted, thus warranting the need for a bibliometric study. This study is a way to observe the amount being produced, which are the main projects under development and which results have been obtained. The current work presents a bibliometric discussion on articles published worldwide concerning kaolinite flotation in international journals from 1992 to 2015. This work allowed to recognize and identify which are the thematic and methodological trends that are being used, in addition to the main collectors used in kaolinite flotation. The results show that a significant amount of articles is produced by Chinese authors, especially from 2013, as China is the largest aluminum producer in the world, and kaolinite is the reject in the reverse flotation process of diaspore. Many studies using methods that are important to understand physicochemical phenomena in flotation, with similar proposals and structures, were found, such as: mineralogical characterization methods, zeta potential, adsorption methods and others. Assessed articles had, on average, 7 pages each and all were searched in Elsevier\'s SciVerse ScienceDirect. Thirty-one out of the 39 analyzed articles have interdisciplinary evaluation of the Coordination for the Improvement of Higher Education Personnel (CAPES) and are rated at stratum A1, which corresponds to higher quality articles. The results showed the difficulty of working with kaolinite flotation individually and confirmed that there is scientific collaboration among authors. The study by keyword (180 in total) found terms as \"aluminosilicate\", \"oxidized ores\" and \"diaspore\" together with \"kaolinite\", in addition to other keywords, such as \"flotation\" and \"adsorption\". Minerals involved in flotation together with kaolinite were also evaluated, and diaspore mineral frequently appears related to the mineral of interest of this dissertation. Articles were rated according to their importance in the academic world using the assessment of citations by Scopus. In addition, bibliometric analysis showed that reagents used in kaolinite flotation tests are mostly derived from cationic nitrogenated compounds. Most used pH values in flotation are acidic, although many collectors also have good results in neutral and/or alkaline media. It was also noted that there is still much to be researched, since most articles sampled researched in laboratory scale and do not describe the reality of processing plants of kaolinite in the world.