EM - Escola de Minas
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/6
Notícias
A Escola de Minas de Ouro Preto foi fundada pelo cientista Claude Henri Gorceix e inaugurada em 12 de outubro de 1876.
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Resultados da Pesquisa
Item Quartz and hematite activation by Zn, Ca and Mg ions in the cationic flotation route for oxidized zinc ore.(2021) Duarte, Geraldo Magela Pereira; Lima, Rosa Malena FernandesAnionic, cationic and cationic/anionic flotation is widely used in the concentration process for low-grade oxidized zinc ores. In the cationic flotation route, sodium silicate is used as a depressant for gangue minerals and amine as a collector for zinc minerals previously activated by sodium sulfide. However, the presence of polyvalent ions in aqueous solution can affect the surface properties of the various minerals and consequently, the selectivity of the process. This study evaluated the effect of Zn, Ca, and Mg ions, originated by the solubility of smithsonite and dolomite, on the surface properties of quartz and hematite. Microflotation tests showed the inefficiency of sodium silicate as a depressant for quartz in aqueous solution even when Zn, Ca, and Mg ions were not present. Activation of hematite by Zn ions was observed, impeding the separation of smithsonite and hematite (iron oxide). Results obtained from the microflotation and zeta potential tests were analyzed based on the speciation diagrams of the reagents and ions studied, as well as published studies.Item Cationic flotation of smithsonite and dolomite from Brazilian Ambrósia Norte deposit.(2019) Souza, Tamiris Fonseca de; Lima, Rosa Malena FernandesThe flotation of low-grade oxidized zinc ores has been commonly used to produce marketable concentrates for many years. Several flotation routes are being successfully used: cationic, anionic and a mixture of anionic and cationic. The choice of the route taken is dependent on the major zinc-bearing minerals in the deposit of interest and its associated gangue. Since both the mineralogical composition of zinc ores and the chemical composition of smithsonite and dolomite vary between deposits, the physico-chemical conditions under which selective flotation processes are determined must be established for each unique case. In this study, cationic flotation tests were performed using smithsonite and dolomite samples from an unstudied oxidized zinc deposit in Brazil, using Na2S as the sulfidizing agent, sodium silicate as the depressant and amine as the collector. The surface charges of both minerals were investigated with and without reagents. These tests showed that the optimum conditions of flotation were reached at pH 11. Na2S allowed a significant increase in the recovery of smithsonite, which implies lower amine consumption. Sodium silicate functioned as a dolomite depressant at concentrations up to 6.0 mg/L. The results for both flotation and the zeta potential of the minerals were analyzed using specimen diagrams of the reagents and compared with studies published in previous literature.Item Effect of EDTA on quartz and hematite flotation with starch/amine in an aqueous solution containing Mn2+ ions.(2016) Lelis, Deisiane Ferreira; Leão, Versiane Albis; Lima, Rosa Malena FernandesIn this paper, a detailed study of the influence of Mn2+ ions on quartz and hematite flotation (at pH 10.5 with starch/amine as depressor/collector) in the absence and presence of ethylenediaminetetraacetic acid (EDTA) is presented. By using zeta potential measurement and a careful analysis of manganese species present in water for dosages in which manganese hydroxide precipitated, we confirmed that the depression of both minerals by Mn2+ ions is due to the following: (i) the adsorption of Mn hydroxy complexes (Mn2(OH)3+ and Mn(OH)+); (ii) Mn2+ and mainly (iii) the precipitation of Mn(OH)2 on mineral surfaces. These effects hindered the adsorption of amine species on the surfaces of the minerals (quartz and hematite). EDTA was used to complex Mn2+ to restore the recoveries of both minerals. This was confirmed by the species distribution diagrams of Mn and EDTA–Mn in water. Conditioning with starch followed by amine at pH 10.5 enabled a selective separation of these minerals.Item Microflotação de caulinita utilizando aminas.(2010) Rodrigues, Otávia Martins Silva; Araujo, Armando Corrêa de; Peres, Antônio Eduardo ClarkO número de estudos a respeito de flotação de caulinita tem crescido nos últimos anos, principalmente, devido às contribuições dos pesquisadores chineses. As bauxitas chinesas apresentam alta quantidade de aluminossilicatos, entre eles caulinita, o que prejudica sua utilização no processo Bayer. Esse trabalho apresenta resultados de testes de microflotação de caulinita com três aminas: dodecilamina (amina primária), Flotigam EDA (eteramina) e Duomeen T (aminagraxa). Dodecilamina e Flotigam EDA apresentaram eficiente ação coletora na concentração de 1x10-4 mol/L. DuomeenT se mostrou eficiente em concentração mais alta, 1x10-3 mol/L. O ponto isoelétrico da caulinita, determinado a partir de medidas de potencial zeta, ocorreu em pH = 4,6. O estudo do potencial zeta da caulinita, na presença e na ausência de dodecilamina e Flotigam EDA, mostrou que a presença de amina no sistema altera seu ponto isoelétrico. Tal variação sugere que ocorreu adsorção dos coletores na superfície da caulinita.Item Aplicação de extensor de cadeia e emulsificante na flotação de minério de ferro.(2013) Silva, José Pedro da; Imbelloni, Alaine Moreira; Pereira, Carlos AlbertoEste trabalho tem como objetivo avaliar o desempenho da flotação reversa de minério de ferro, usando coletor (amina), na presença e na ausência de extensor de cadeia (óleo diesel) e emulsificante (lauril sulfato de sódio). Foram realizados seis ensaios de flotação com duplicata. Os ensaios utilizando amina, óleo diesel e lauril sulfato de sódio são os que mostram um melhor resultando, apresentando recuperação metálica de 91,82% e sílica no concentrado igual a 1,68%. Assim, comprova-se que o uso do extensor de cadeia e emulsificante, em conjunto com a amina, evidencia um melhor resultado na flotação, em termos de recuperação metálica e seletividade, comparativamente ao uso de apenas amina, ou amina com óleo diesel.