EM - Escola de Minas

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Characterization of magnetic tailings from phosphate-ore processing in Alto Paranaíba.
(2023) Silva, Fernando Brandão Rodrigues da; Araújo, Fernando Gabriel da Silva; Krüger, Fernando Leopoldo von; Silva, Guilherme Jorge Brigolini; Batista, Ronaldo Junio Campos; Manhabosco, Taíse Matte
The characterization studies of tailings from mining are crucial for the development of its reuse processes and the reduction of impacts caused by its conditioning on the earth’s surface. This study characterizes the magnetic tailings from phosphate-rock processing using X-ray diffraction, X-ray fluorescence spectrometry and quantitative electron microscopy techniques. Samples were obtained from the magnetic tailings deposit of a mining company in the Alto Paranaíba region, Minas Gerais. The tailings are mainly composed of hematite/magnetite (74.92%), ilmenite (8.91%), fluorapatite (8.8%), anatase (3.07%), calcite (1.67%), goethite (1.62%), and quartz (1.02%). The particle size of the tailings is smaller than that specified for the production of sinter feed. The hematite/magnetite phase is strongly associated with ilmenite and fluorapatite. New stages of comminution and separation are needed due to the low degree of liberation of these minerals for a possible reuse of the components.
Effect of Nb addition on the machinability of a pearlitic gray cast iron.
(2022) Reis, Bárbara Cristina Mendanha; Santos, Anderson Júnior dos; Pereira, Natália Fernanda Santos; Carmo, Denilson José do; Faria, Geraldo Lúcio de; Câmara, Marcelo Araújo; Faria, Paulo Eustáquio de; Abrão, Alexandre Mendes
Due to its high thermal conductivity, good damping performance and superior machinability, gray cast iron (GCI) has found many applications in the automotive industry. However, this material has given way to other cast irons due to the need for materials with higher mechanical strength and toughness. Actual efforts have been made to reformulate the GCI chemical composition to obtain different microstructures for improving its mechanical properties. In this study, the influence of Nb content on the microstructure and machinability of GCI was investigated when turning under cutting speeds of 240, 360, and 480 m/min, feed rates of 0.25 and 0.50 mm/rev, and using two different chip breaker geometries (Flat Top and GH). The Nb addition decreased the graphite size and refined the pearlitic interlamellar spacing. However, it did not produce significant alteration in the number of eutectic cells and hardness. Regardless of the Nb content, the presence of chip breaker GH and the lower levels of cutting speed and feed rate were associated with superior machinability. The increase in the Nb content in the GCI raised all the components of the machining forces, yet it did not promote significant changes in the chip temperature and decreased the surface roughness after turning.
Use of canga as dimension stone.
(2018) Nogueira, Francielle Câmara; Menezes, Samara Santana; Russo, Mário Luís Cabello; Pereira, Carlos Alberto
Canga is a residual product resistant to mechanical weathering and practically inert chemical weather. The wide occurrence of this material in the region of Ouro Preto viability their use on behalf of the community and encourage studies about their physical and chemical properties. In this context, this pioneering research supporting the use of canga in the ornamental rock sector focus as dimension stone. The samples collected in geological site of Ouro Preto was characterized using x-ray diffraction, density and porosity determinations, Rockwell hardness test, Schmidt rebound hammer test and chemical analysis. The Schmidt rebound hammer tests were very efficient to detect internal imperfections, which was proven by the test of porosity. In addition, the fact of this test be non - destructive with easy realization makes their use viable, because there is no material lost. The performance of material compared with quartzite, usually used as dimension stone, was proved for this purpose. Its properties even suggest the application in other sectors such as ceramics and construction.
A geometallurgical comparison between lump ore and pellets of manganese ore.
(2015) Faria, Geraldo Lúcio de; Tenório, Jorge Alberto Soares; Jannotti Júnior, Nelson; Araujo, Fernando Gabriel da Silva
Manganese lump ores are still the main rawmaterial used in the manufacture ofmanganese ferroalloys, but the processing of the ore to the beneficiation point generates fines. So an alternative to be studied is making pellets. Thiswork compares themain geometallurgical characteristics of the lump ore fromthe AzulMine and the pellets made from fines generated during beneficiation of this lump ore on a small scale. The characteristics assessed were: the chemical composition, mineralogical constitution, hot and cold particle disintegration, thermal decomposition and solid state reduction. It can be observed that the pellets contain a greater proportion of manganese oxides than the lump ore and they are also richer inMn. In the pellets the hot and cold particle disintegration phenomena are minimal when compared with those found in lump ore. Lump ore can be efficiently reduced in the solid state, while most of the manganese minerals in the pellets have already been reduced to MnO. The conclusion is that manufacturing pellets in order to take advantage of the manganese ore fines is a path that must be studied further, since the pellets can be used as a viable source of manganese and act as agents that contribute to the increase in permeability of the charge. But possible reductions in the temperature of the granular zone during solid state reduction need to be considered.

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