EM - Escola de Minas
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/6
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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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Item Reverse cationic flotation of iron ore by amide-amine : bench studies.(2022) Rocha, Geriane Macedo; Cruz, Marcus Vinicius Macedo da; Lima, Neymayer Pereira; Lima, Rosa Malena FernandesThis study evaluated the performance of a new collector amide-amine compared with a traditional etheramine in conventional reverse cationic flotation of a siliceous itabirite sample of the Quadrilatero Ferrı ́fero (d80 1⁄4 116 mm, 40% Fe and 41.2% SiO2). Statistical design of experiments was used to determine the influence of pH, collector and starch dosages on mass and Fe recoveries, Fe and SiO2 grade in the concentrate, Fe grade in the tailings and Gaudin's selectivity index (S.I). For the amide-amine, starch had no significant effect on mass recovery and in the Fe and SiO2 grade in the concentrate. For the same dosages, it was found that amide-amine was less selective than etheramine. However, at higher dosages, at pH 8 and without starch, concentrates with Fe >65% and SiO2 <5% grades were obtained, similar to the grades obtained with etheramine and starch at pH 10.5. The mass and Fe recoveries were higher and consequently, the Fe grades in the tailings were lower. These results indicate that, despite the higher dosage required, amide- amine is selective without starch, which is very interesting from the economic point of view and simplification of the process route, implying a great potential for its industrial application.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 Effect of magnesium species on cationic flotation of quartz from hematite.(2020) Lelis, Deisiane Ferreira; Lima, Rosa Malena Fernandes; Rocha, Geriane Macedo; Leão, Versiane AlbisIn the Quadrilátero Ferrífero Region, located in the state of Minas Gerais – Brazil, the utilization of recycled water from the tailing dams in the reverse cationic flotation of siliceous iron ores is common practice. In such process, ore concentrates assigning dolomite (2.5% to 10%) besides quartz in the mineral gangue, do not reach the desired specification for the production of blast furnace pellets (≤2% SiO2) given the loss of selectivity occurring in the separation of quartz from the Fe-bearing minerals, which can be related to a rise in the ions Ca and Mg in an aqueous medium resulting from the dissolution of dolomite. With a view to improving the reverse cationic flotation route for this type of ore, fundamental studies (microflotation trials, zeta potential, adsorption/Fourier-transform infrared spectroscopy) into the effect of the Ca and Mg ions in the cationic flotation with the use of pure quartz and hematite mineral samples were carried out. The results attained with the Ca ions were presented in previous studies by the authors. The current investigation presents the results achieved with the Mg ions, added in water as MgCl2. In the microflotation trials carried out at pH 10.5, amine dosage for maximum recovery of quartz (2.5 ppm) and hematite (50 ppm) was applied. A strong depression of hematite by starch was confirmed, which did not occur with quartz. In the case of the Mg ions, a stronger depression effect was observed, if compared to starch, for the two minerals, starting from a dosage of 10 ppm of MgCl2. After the conditioning of both minerals with 10 ppm of MgCl2, followed by conditioning with 10 ppm of starch, the recoveries attained were negligible (3.5% to 4.4%). Based on thermodynamic data, zeta potential measurements, and infrared spectroscopy, it was concluded that the strong depression effect caused by the Mg ions on both minerals owes to the adsorption of the Mg2+ and MgOH+ species and also the precipitation of Mg(OH)2, where the starch is chemically adsorbed, preventing further amine adsorption. Only quartz recovery was reestablished after the complexation of the Mg ions in the water by ethylenediaminetetraacetic acid having close molar concentrations to the molar concentration of the Mg ions followed by starch conditioning. The results presented indicate the need for a reduction in the concentration of Mg in the water used, before flotation is conducted.Item Effects of calcium and chloride ions in iron ore reverse cationic flotation : fundamental studies.(2019) Lelis, Deisiane Ferreira; Cruz, Daniel Geraldo da; Lima, Rosa Malena FernandesIn this work, the simultaneous effects of Ca2+ and Cl− ions in an aqueous solution at pH 10.5 on the flotation of quartz (the main impurity in itabiritic iron ore) and hematite by starch and amine was investigated. A strong depression in the flotation of both quartz and hematite conditioned with CaCl2 was observed. This effect was higher for hematite than for quartz. Based on zeta potential measurements and the speciation diagram of calcium in aqueous solutions, the physical adsorption of Ca2+ on the surfaces of both minerals was inferred. The infrared spectrum of quartz conditioned with CaCl2 at pH 10.5 was similar to its reagent-free reference spectrum. However, a new band at the wavenumber of 1465 cm−1 was identified in the spectrum of hematite conditioned with CaCl2; this band did not exist in its reference spectrum. This new band may indicate the chemical adsorption of Cl− ions on the hematite surface. The complexation of Ca2+ by ethylenediaminetetraacetic acid enabled complete quartz recovery with amine. For hematite, recovery was partially restored, probably because of the positive chlorocomplexes on the hydrated iron surfaces of hematite, which prevented the adsorption of aminium ions at these sites. Therefore, the selective inverse cationic flotation of itabiritic iron ore at pH 10.5 in water containing Ca2+ is possibly only after complexing them with EDTA.Item Bench-scale calcination and sintering of a goethite iron ore sample.(2016) Silva, Mônica Suede Santos; Lima, Margarida Márcia Fernandes; Graça, Leonardo Martins; Lima, Rosa Malena FernandesThis work presents the results of bench calcination and sintering studies conducted on an iron ore sample from Iron Quadrangle, Brazil with high goethite content. The natural samples and the products of calcination and sinteringwere characterised by inductively coupled plasma optical emission spectroscopy (OES/ICP), X-ray spectrometry and gravimetric methods. Optical microscopy, X-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDS) were used to identify the phases in the studied samples. Density, specific surface area, specific pore volume and pore diameter were determined through gas pycnometry. All of the natural sinter feed samples had a Fe grade N64% and a very high phosphorus grade (~0.17%). After calcination, a 3.1–3.4% increase was observed in the Fe grade compared to that of the natural sinter feed samples. The average Fe grade of the sintered samples was 59.1%. The identified phases with XRD in the raw materials were hematite and goethite. In the calcined samples, only hematite was identified because of the thermal decomposition of goethite. The density, specific surface area, specific pore volume and pore diameter of the calcined samples increased compared to those of the natural sinter feed samples. Hematite, brownmillerite, anorthite, and gehlenite were identified in the sintered samples. The sites for phosphorus occurrence were calcium silicates and apatite. The sintered samples exhibited specific surface areas lower than those of the calcined samples. This result was ascribed to the destruction of the pore structure by the sintering process.No relationship between the proportions of nucleate, intermediate and agglomerate particles used inmixture of sinter testswith the results of microtumbler was identified.Item Efeito da adsorção de amina no potencial zeta da hematita e do quartzo.(2003) Lima, Rosa Malena Fernandes; Quirino, LucineiEsse trabalho teve por objetivo estudar o efeito de uma eteramina sobre o potencial zeta dos minerais hematita e quartzo. As amostras utilizadas possuíam alto grau de pureza, com granulometria na faixa de 53 a 44m. O reagente utilizado foi um acetato de eteramina a 50% de grau de neutralização. Foi utilizada a célula eletroforética, Zeta potencial - Model 1202, fabricada pela Micromeritcs. Em uma primeira fase, determinou-se a curva de potencial zeta da hematita e do quartzo, condicionados somente com água destilada. O IEP da hematita ocorreu em valores de pH entre 6 e 8. Os valores de potencial zeta do quartzo foram negativos para todos os valores de pH (6 a 12). Nos ensaios utilizando soluções de amina, observou- se que o potencial zeta dos dois minerais tornou-se menos negativo em relação aos ensaios na ausência desse reagente e que essa diminuição, no caso do quartzo, foi bem mais acentuada que a da hematita. Observou-se a mudança de sinal de negativo para positivo do potencial zeta do quartzo entre o pH 9 e 10 para a dosagem de amina a 3,54x10-4M.