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
3 resultados
Resultados da Pesquisa
Item Abrasiveness of iron ores : analysis of service-worn conveyor belts and laboratory Dry Sand/Rubber Wheel tests.(2022) Nins, Barbara; Penagos, Jose Jimmy; Carneiro, Leandro Moreira; Münch, Daiane; Falqueto, Patrick Amaral; Viáfara, Cristian Camilo; Costa, Adilson Rodrigues daBelt conveyors are currently one of the most commonly used technologies for transporting iron ore. Of the components of the conveyor system, the belt is the most expensive and susceptible to damage. Failures due to wear of the rubber cover lead to downtime for corrective maintenance, greater operational risks and performance and economic losses. To improve the tribological performance of conveyor belts, it is necessary to know the main parameters that influence their wear. As wear behavior is not an intrinsic property of a material, the most reliable results are obtained when the wear mechanisms produced in laboratory tests are similar to those in service. In this work, two types were investigated of belt rubber, one new and one worn in service, and four types of iron ore in two class sizes. Loose abrasive wear tests were carried out using the Dry Sand/Rubber Wheel apparatus with belt rubber test pieces and iron ores as abrasives. This work characterized the wear mechanisms that occur in service and in laboratory tests. The predominant wear mechanism found was the formation of Schallamach waves. In the wear tests, Friable Hematite samples presented the highest abrasiveness. In addition, the chemical, mineralogical and morphological features of the iron ore samples were characterized. The high abrasiveness of Friable Hematite was possibly due to the mineral assembly.Item The infrared spectra of amine collectors used in the flotation of iron ores.(2005) Lima, Rosa Malena Fernandes; Brandão, Paulo Roberto Gomes; Peres, Antônio Eduardo ClarkInverse froth flotation is the most used concentration method for itabiritic iron ores, where the quartz gangue is floated, and the iron oxides are kept depressed by starches; medium-chain etheramine acetates are the cationic collectors used. Since there is a lack of thorough studies on the infrared spectroscopy of these reagents (and by other similar techniques), an investigation on the band assignment in the infrared spectra of a typical etheramine acetate was carried out by Fourier-transform infrared spectrometry. To distinguish the bands due to the cationic amine ion from the acetate anion ones, a molecular decyletheramine was also studied, as well as its salts, after some degrees of neutralisation, by acetic or hydrochloric acids; also, potassium acetate was included, to assess the anion bands alone. From this approach, all the significant bands were successfully assigned to the important functional groups in the collector_s molecule: NHx, C H2, C H3, –O–, and the acetate bands. A confirmation of this method was the identification of the amine cation bands alone, without the presence of the previously associated acetate bands, after adsorption onto the surface of quartz particles, from an aqueous solution of a decyletheramine acetate, at pH = 10.5.Item First results on the LPO-derived seismic properties of iron ores from the Quadrilátero Ferrífero region, southeastern Brazil.(2008) Morales, Luiz Fernando Grafulha; Lagoeiro, Leonardo Evangelista; Endo, IssamuDeterminations of the LPO-derived seismic properties of iron ores were carried out in five samples with contrasting mineralogy (hematite, magnetite and quartz) and deformed in different conditions. All the samples are seismically quasi-isotropic or weakly anisotropic, which reflect (i) an absent or weak crystallographic preferred orientation (CPO) in some samples; (ii) the high modal content of magnetite, (iii) the relatively weak anisotropy of elastic stiffness of hematite single crystal. Such variables induce a low anisotropic seismic behavior even in high strained iron ores with strong preferred orientation of hematite. A plane of seismic transversal isotropy parallel to the foliation of the aggregates is developed in hematite ± magnetite aggregates and in itabirites with strong CPO of hematites. In these high strained aggregates, some relationships between the crystallographic axes of hematite and the propagation velocities can be observed. The magnitudes of P and S-wave velocities derived of hematite CPO are lower than the values experimentally determined in iron ores. Such a difference probably reflects other microstructural variable which were not taken into account in the present contribution (e.g. shape preferred orientation).