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.
Navegar
5 resultados
Resultados da Pesquisa
Item Characterisation and magnetic concentrationof an iron ore tailings.(2018) Dauce, Pedro Domingos; Castro, Guilherme Bernardes de; Lima, Margarida Márcia Fernandes; Lima, Rosa Malena FernandesThe Quadrilátero Ferrífero mineral province is one of the most important sources of ironore in Brazil. Nowadays this region produces 65% of the Brazilian iron ore. However, sincethe 1970s, there has been a continuous depletion of high Fe grade ores, obliging the mineralcompanies to concentrate low Fe grade ores in order to reach the quality demand of thesteel mills. It is estimated that 400 kg of tailings is produced for each tonne of beneficiatediron ore. This means there is a very big volume of tailings dumped from industrial plantsover the years. Owing to the inefficiency of the industrial operations, the tailings depositedin tailings dam have Fe grades similar to or higher than the Fe grades of some iron oresexploited nowadays (30–45 wt%). Therefore, the reprocessing of this material can recovermillions of tonnes of discharged Fe and decrease the volume of the existent tailings, whichcan be interesting for the environmental and economic sustainability of this region. Herein,we present the characterisation of a tailings sample from a gravity concentration circuitof a mine located in northwest of Quadrilátero Ferrífero with the objective of proposing aconcentration route for this material. The main characteristics of this tailings sample were:d80= 4 mm; grades of 30.3 wt% Fe and 55.4 wt%SiO2, while the identified minerals by XDR,optical microscopy and thermal analyses were quartz, hematite (martitic, lamellar, granu-lar, sinuous, specularitic), goethite (alveolar, amphibolitic, botryoidal), magnetite, kaolinite(5.3 wt%) and apatite (0.7 wt%). Liberation of quartz for size fraction – 0.150 mm was of 80%.Bench magnetic concentration of this material increased the Fe grade up to 23 wt% anddecreased the SiO2grade up to 39.4 wt% in the obtained concentrates, which is satisfactoryfor the rougher concentration step.Item Sintering of manganese ore tailings under an argon atmosphere.(2016) Lima, Margarida Márcia Fernandes; Valduga, Fillipe; Lima, Rosa Malena FernandesManganese is a chemical element widely used in Metallurgy. In Brazil, the ore’s beneficiation processes discharge the tailings (fraction size 0.106mm) with considerable Mn content. It would be interesting to recover this material. The aim of this work was to obtain and characterize the sinters from the manganese ore tailings at the Morro da Mina Mine. The fines (37 μm) were calcinated at 800°C for 3600s, and afterwards, homogenized with activated charcoal (7 and 10%) and CaO (5 and 10%). The sintering were carried out at 1135, 1140 and 1145°C during 7200 and 14400s under an argon atmosphere. The sintered products were characterized by BET surface area, apparent density, X-ray diffraction, MO and SEM/EDS. The presence of potassium from the alkalis justified the low melting point of the tailings (1145°C). Due to the chemical complexity of the tailings, several phases were identified in the products: pores, silicates with a high content of manganese in the matrix, as well as other silicates with different proportions of Al, Mn, Mg and Ca, pure Fe, and SiO2, etc.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 Caracterização de talco purificado de resíduos de pedra sabão.(2014) Garcia, Neylor Henrique; Rodrigues, Michael Leonardo Marques; Lima, Margarida Márcia Fernandes; Lima, Rosa Malena FernandesNesse trabalho estão apresentados os resultados dos ensaios de caracterização de talco purificado de resíduos de pedra sabão, oriundos de Santa Rita de Ouro Preto, após lixiviação de concentrados de flotação com ditionito de sódio (Na2S2O4) e ácido clorídrico (HCl). A caracterização tecnológica desses materiais constou de análise granulométrica, efetuada por espalhamento de raios laser (Cilas 1064), difração de raios X (método do pó total), análises químicas, efetuadas por espectroscopia ótica de emissão-plasma de acoplamento indutivo além da determinação de alvura ISO. Para os concentrados de flotação lixiviados com ditionito de sódio e ácido clorídrico foram obtidas alvuras de 73,7 e 79,6%, respectivamente, representado aumento de 3 e 9% em relação a alvura do concentrado da flotação. Verificou-se que cerca de 80% das partículas das amostras de talco lixiviadas encontravam-se abaixo de 10 μm. Os minerais identificados nos difratogramas de raios X foram talco e clinocloro. O maior aumento da alvura do produto lixiviado com HCl, está relacionado com a diminuição dos teores de Fe2O3, Ni, Zn em relação à alimentação (concentrado da flotação).Item Calcination and characterisation studies of a Brazilian manganese ore tailing.(2014) Pereira, Mário J.; Lima, Margarida Márcia Fernandes; Lima, Rosa Malena FernandesThis paper discusses the systematic analysis of the results of calcination as a function of size fraction performed on a sample of Brazilian silicate–carbonate manganese ore tailing at 800 °C. The raw materials and the corresponding calcination products were analysed using several analytical techniques, including determination of density, specific surface area and porosity, chemical analysis and X-ray diffraction. Themorphology and chemical composition of the calcination products were analysed by using scanning electronic microscopy equipped with energy-dispersive X-ray spectrometer (SEM/EDS). Results indicate that the manganese ore tailing consists of silicates, namely, spessartine (Mn3Al2(SiO4)3), tephroite (Mn2(SiO4)) and rhodonite ((Mn,Fe,Mg,Ca)5(SiO3)5) and rhodochrosite (MnCO3). The loss of CO2 and OH during the thermal decomposition of the carbonate (rhodochrosite and dolomite) and hydrated minerals (kaolinite, muscovite and antigorite) in air atmosphere at 800 °C resulted in: (1) decrease of the specific surface area and porosity, (2) increase in the density and Mn grade from 27.6% to 32.2% and (3) increase in SiO2 grade from 26.7% to 30.1%. These results indicate that this material is within the chemical specifications of Fe–Si–Mn alloy.