Title

CHARACTERIZATION OF QUADRILATERO FERRIFERO’S IRON ORES USED IN SINTERING PROCESSES

CHARACTERIZATION OF QUADRILATERO FERRIFERO’S IRON ORES USED IN SINTERING PROCESSES

Authorship

MAGALHÃES, MARILIA S. DE; BRANDÃO, PAULO R. G.; TAVARES, ROBERTO P.

MAGALHÃES, MARILIA S. DE

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BRANDÃO, PAULO R. G.

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TAVARES, ROBERTO P.

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DOI

10.5151/2594-357x-5MinFe-91-100

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Abstract

Iron ores of three mines (A, B and C) located in Quadrilatero Ferrifero (Minas Gerais State, Brazil) were studied. They comprise actually mixes of hematite-rich typologies and goethite in minor grades, which have a specific particle size, mainly distributed from 6.35mm to 0.105mm (sinter feed). These three blends were used in agglomeration processes to produce sinters. The mineralogical characterization of the ore mixes was firstly carried out by X-ray diffraction, followed by observations of polished sections by means of optical (reflected light, MOLR) and scanning electron (backscattered electrons images, SEM-BSE) microscopy, which allowed the mineralogical details and microstructure assessment. The bulk chemistry was also evaluated by the classic methods and the mineral chemistry was recognized from many microanalyses using energy-dispersive X-ray spectrometry (EDS). Lamellar and elongated granular hematites (Ht) are related to the A sinter feed (SFA); the granular type is common in the SFB; granular and elongated granular Ht are common in the SFC. Ht has pure composition. Many morphologies of goethite were identified in these mixes. Goethite generally incorporates Si, Al, P and sometimes Mn in its composition. Magnetite (Mt) is not largely distributed in these ores; when it has been described, it is generally martitized or it appears as relicts mainly in Ht of the SFB. In this case, Ht can retain the characteristics of the martitization process, corresponding to martite. Quartz, kaolinite and gibbsite constitute the main gangue minerals. The mineral association observed in the sinter feed samples is directly related to their chemical characteristics: higher FeO contents in the SFB attest the regular distribution of magnetite in this sinter feed. The variations of the gangue mineral contents are also identified by the distribution of SiO₂, Al₂O₃ and MnO in each sinter feed.

Iron ores of three mines (A, B and C) located in Quadrilatero Ferrifero (Minas Gerais State, Brazil) were studied. They comprise actually mixes of hematite-rich typologies and goethite in minor grades, which have a specific particle size, mainly distributed from 6.35mm to 0.105mm (sinter feed). These three blends were used in agglomeration processes to produce sinters. The mineralogical characterization of the ore mixes was firstly carried out by X-ray diffraction, followed by observations of polished sections by means of optical (reflected light, MOLR) and scanning electron (backscattered electrons images, SEM-BSE) microscopy, which allowed the mineralogical details and microstructure assessment. The bulk chemistry was also evaluated by the classic methods and the mineral chemistry was recognized from many microanalyses using energy-dispersive X-ray spectrometry (EDS). Lamellar and elongated granular hematites (Ht) are related to the A sinter feed (SFA); the granular type is common in the SFB; granular and elongated granular Ht are common in the SFC. Ht has pure composition. Many morphologies of goethite were identified in these mixes. Goethite generally incorporates Si, Al, P and sometimes Mn in its composition. Magnetite (Mt) is not largely distributed in these ores; when it has been described, it is generally martitized or it appears as relicts mainly in Ht of the SFB. In this case, Ht can retain the characteristics of the martitization process, corresponding to martite. Quartz, kaolinite and gibbsite constitute the main gangue minerals. The mineral association observed in the sinter feed samples is directly related to their chemical characteristics: higher FeO contents in the SFB attest the regular distribution of magnetite in this sinter feed. The variations of the gangue mineral contents are also identified by the distribution of SiO₂, Al₂O₃ and MnO in each sinter feed.

Keywords

iron ore, characterization, mineralogy

iron ore, characterization, mineralogy