Caracterización química y mineralógica de refractarios de Al₂O₃-MgO-C

Abstract

Los refractarios de Al 2 O 3 -MgO-C, de gran interés tecnológico por sus excelentes propiedades, se utilizan mayoritariamente en las industrias del hierro y el acero. Estos materiales están constituidos por distintas calidades de corindón, periclasa y grafito a los que se añaden pequeñas cantidades de metales y un polímero que actúa como ligante. En este trabajo establece una metodología para la caracterización química y mineralógica de refractarios de Al 2 O 3 -MgO-C. Los resultados del análisis químico realizado por fluorescencia de rayos X, espectroscopia de emisión de plasma y gravimetría, junto con la información cualitativa acerca de las fases cristalinas (obtenida por difracción de rayos X), y el conocimiento de las materias primas con las que están formulados (obtenido por análisis térmico diferencial y termogravimétrico y microscopia óptica de luz reflejada), se han utilizado para conocer la composición de los refractarios. Los datos obtenidos por las diferentes técnicas dan validez a la metodología desarrollada. Palabras clave: refractarios Al 2 O 3 -MgO-C, microscopia óptica, difracción de rayos X, fluorescencia de Rayos X, espectroscopia de emisión de plasma. Chemical analysis of Al 2 O 3 -MgO-C refractoriesThe Al 2 O 3 -MgO-C refractories, of great technological interest for its excellent properties, are used in a wide range of furnacelining applications such as iron and steel. These materials are composed of various grades of alumina, magnesia, graphite and metallic additives, which are added to a resin that acts as binder. The variety of components oxides, metals and polymers makes the study of these refractories a complex task. Considering this diversity to characterize these materials has been used several techniques: X-ray fluorescence, plasma emission spectroscopy and gravimetry, complemented by X-ray diffraction, differential thermal analysis and thermogravimetry and reflected light optical microscopy. This paper provides a methodology for chemical and mineralogical characterization of these refractory materials. The results of chemical analysis together with the qualitative information on the crystalline phases and the raw materials with which they are formulated have been used to quantify the composition of the refractories using rational analysis. The data obtained by the different techniques validate the methodology developed. Vol 51, 6, 305-312, Noviembre-Diciembre 2012 ISSN 0366-3175. eISSN 2173-0431. doi: 10.3989/cyv.422012 Keywords: Al 2 O 3 -MgO-C refractories, optical microscopy, X-ray diffraction , X-ray fluorescence, plasma emission spectroscopy. Boletín de la Sociedad Española de Cerámica y Vidrio INTRODUCCIÓNDesde los años 80, los refractarios de MgO-C y de Al 2 O 3 -MgO-C (AMC) (1-7) se utilizan cada vez más frecuentemente en las industrias del hierro y el acero, lo que ha dado lugar a una significativa mejora en los procesos metalúrgicos. Más específicamente, los ladrillos de MgO-C se usan como revestimiento en los hornos eléctricos de arco y en línea de escoria de las cuchara...

Characterization of alumina-magnesia-carbon refractory bricks containing aluminium and silicon

“…The present paper is a continuation of previous ones reported by the authors [1,2], in which results of the characterization of aluminamagnesia-carbon materials (Al 2 O 3 -MgO-C, AMC) were presented. The data generated in this type of research is fundamental to understanding the behaviour of the materials in service conditions (as was done in other papers by the authors), with the final aim of establishing what the determining factors are.…”

“…This work is focused on the characterization of a commercial AMC brick, labelled as AMC4, which is used in the bottom of a ladle in a local steel shop. The methodology used in this case was analogous to that designed for the evaluation of AMC bricks with similar MgO contents (∼ 5-7 wt%) and a phenolic resin as an organic binder (AMC1 and AMC3), containing only metallic aluminium as antioxidant [1,2], and whose results are contrasted with those obtained in the present work. However, some changes should be made to the methodological scheme when the presence of Si is detected in AMC4, and some other additional analytic techniques were also used:…”

“…Mineralogical composition: determined by qualitative X-ray diffraction (XRD) together with observations made by reflected light optical microscopy and scanning electron microscopy coupled with X-ray dispersive energy (SEM/EDS). The quantification of the main components was carried out by the rational analysis of the chemical analysis data, as was previously reported [1].…”

“…Chemical composition: an ad-hoc methodology described in a previous paper by the authors was used [1] that combines X-ray fluorescence (XRF), plasma emission spectroscopy (ICP-OES) and gravimetry to analyse powdered samples previously treated according to specific thermal schedules. Considering the composition of AMC4, some changes to the original methodology should be made.…”

“…The presence of silicon required modifications to be made in the experimental strategy previously used, and new techniques were also applied, including the thermodynamic simulation of the material's thermal evolution. The results obtained were analysed, and a comparison was made with those of previously characterised AMC bricks with similar MgO contents and metallic aluminium as an antioxidant [1,2]. Finally, AMC refractories were analysed regarding their chemical resistance to air oxidation and basic slag corrosion, with the aim of finding the main factors which determine the differences in the behaviour of each brick.…”