Abstract

In this study, it was evaluated the chemical interaction between iron ore (Fe2O3) and a refractory concrete based on Al2O3- MgAl2O4 at 1650 °C for 4 h using an  air atmosphere, in order to determine the chemical behavior and possible reactions between these materials. After testing, the refractory concrete was microstructurally characterized by optical microscopy and scanning electron microscopy (SEM-EDS), as well as X-ray diffraction and Raman spectroscopy. The results showed that magnesium aluminate phase incorporates in solid solution Fe+2 ions, resulting in the formation of (Fe, Mg) (Al2O4) spinels and after their saturation, the rest of Fe+2 ions tends to precipitate at the grain boundaries of alumina and magnesium aluminate phases. This fact promotes during the concrete cooling, the formation of wustite, hematite and magnetite phases (detected in the microstructure as a dendritic and widmanstätten morphologies). The presence of hematite phase was corroborated by X-ray diffraction; likewise the presence of modified spinel phase whose hkl reflections width is higher compared with the original spinel, due to the incorporation of Fe+2 in the initial MgAl2O4 phase. For Raman spectroscopy, it was confirmed the presence of corundum (alumina) phase at characteristic frequencies of 378, 416 and 644 cm-1, hematite phase at 226, 292, 411 and 612 cm-1, magnetite phase at 520 and 668 cm-1 and spinel MgAl2O4 and (Fe, Mg) (Al2O4) ) with its main frequencies at 406 and 666 major cm-1.