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This work has characterized an original serpentinite sample and after calcination in a muffle furnace at 1200°C. Analytical techniques were used: chemical analysis, X-ray diffractometry (XRD), microstructures by SEM and EDS. The XRD confirmed the phyllosilicate minerals, lizardite and talc, as the main constituents of this sample, and magnetite in a smaller quantity. Thermogravimetry (TG and DTG) was performed up to 1450°C and the results showed a total mass loss of 12.15%, in addition to two peaks: lizardite at 645°C and talc at 729°C.To analyze the ferrous phases, Mössbauer spectroscopy was used, with spectra recorded at room temperature. In addition, the calcined sample was also analyzed at the very low temperature of 25K. These results have confirmed the phase composition, with the decreasing amount of magnetite and the significant presence of magnesioferrite. The dominant phases were forsterite and enstatite, both containing iron in their composition. By microstructure analysis, the morphological change of the particles was observed, with an expressive decrease of the fine fibers, for more rounded rod-like shapes indicating the beginning of the sintering process. [ABSTRACT FROM AUTHOR]

Due to the complexity of itabirite ores, their characterization is required, with emphasis on microstructure. Widely used is the scanning electron microscope (SEM) with the chemical energy-dispersive microanalyzer (EDS). An efficient computerized analytical system is MLA (Mineral Liberation Analyzer) which uses backscattered electrons images (BSE) and X-ray spectra (EDS) to identify the minerals in polished sections of ore particles. Thus, microstructural composition maps are generated, with very important information such as liberation, mineral associations and modal analysis. There is excellent statistical significance because several thousand particles are analyzed. Four samples of iron ores from the Iron Quadrangle, Minas Gerais, with different degrees of microstructural complexity have been studied. The particle sizes (-0.500 +0.300 mm and -0.300 +0.212 mm) were analyzed by X-ray diffraction, Mossbauer spectroscopy and MLA. By the instrumental methods, abundant minerals were quartz and hematite, obviously; also identified were goethite, and minor gibbsite and magnetite. In general, these data were consistent with MLA's. Some minor inconsistences between the global chemical analyses and the quantitative microstructure data are due to the different localized analytical sampling and the degree of homogenization. Quartz liberation was above 90% in three samples; the exception was the APV4 sample with only 60% quartz liberation, where quartz is associated with hematite (mainly) and goethite. [ABSTRACT FROM AUTHOR]

The study of pellets morphology is an important tool to understand possible mechanisms involved during its reduction reaction. Thus, the aim of this paper is characterize three different iron ores and correlate its morphology obtained after the complete reduction with its features. The reductions tests were accomplished in a horizontal tubular furnace at 850°C. Two reducing atmosphere were used. The first one contained hydrogen. The second one was a mixture between first gas + carbon monoxide. The iron ore characterization was carried out by size analysis, surface area and X-ray analysis. Scanning electron microscopy was used to obtain the morphology from the reduced pellets. The results showed a greater number of whisker were obtained with more fine ore. Furthermore, it was noted that carbon monoxide provided a lesser number of pores and greater number of whisker. [ABSTRACT FROM AUTHOR]

Iron ore exploited in Brazil can be classified into several lithological types which have distinct features. The progress of mining over time leads to scarcity of high grade iron ores, leading to the exploitation of poor, contaminated and compact ores. There is a growing trend of application of process flowsheets involving grinding to promote mineral liberation, essential condition for concentration processes. Several authors have correlated metamorphism processes of banded iron formations to mineralogical features observed on itabirites from the Iron Quadrangle, mainly the crystals size. This paper presents the implications of such variation in defining the mesh of grinding. Mineralogical characterization and grinding, desliming and flotation tests have been carried out with samples from two regions of the Iron Quadrangle subjected to different degrees of metamorphism. It was found a trend of reaching satisfactory liberation degree in coarser size for the itabirite of higher metamorphic degree, which has larger crystals. The flotation tests have confirmed the mineralogical findings. [ABSTRACT FROM AUTHOR]

The Lagoa das Flores Mine is an important iron ore deposit located at the Serra Azul complex in the Northwestern border of the Ferriferous Quadrangle, Minas Gerais, where other important mines also occur, such as Arcelor Mittal, Usiminas, MBL and MMX. Presently 2.2 Mt/year of waste are generated; 70% of this waste is comprised by compact itabirite whose mineral resource is of the order of 370 Mt. The goals are to perform a mineralogical characterization and the development of process routes for this ore type by bench scale testing. The latter was carried out by work index and abrasion index determinations and magnetic concentration, desliming and flotation testing. The ore was composed by quartz, martitic hematite and minor magnetite; the average iron content was 34.3% and the quartz liberation degree was 92% below 0.075 mm. The best processing route are grinding to -0.15 mm, followed by medium and high strength field magnetic concentration, regrinding to -0.053 mm and reverse cationic flotation. Therefore, a final concentrate with 67.8% Fe, 1.84% SiO2 contents and metallic recovery of 83% is obtained. [ABSTRACT FROM AUTHOR]