Lab Scale Study of the Depletion of Mullite/Corundum-Based Refractories Trough Reaction with Scaffold Materials

To investigate the mechanisms underlying the depletion of mullite/corundum-based refractory bricks used in rotary kilns for iron ore pellet production, the reaction mechanisms between scaffold material and refractory bricks have been studied on the laboratory-scale. Alkali additions were used to enhance the reaction rates between the materials. The morphological changes and active chemical reactions at the refractory/scaffold material interface in the samples were characterized using scanning electron microscopy (SEM), thermal analysis (TA) and X-ray diffraction (XRD). No reaction products of alkali and hematite (Fe2O3) were detected; however, alkali dissolves the mullite in the bricks. Phases such as nepheline (Na2O center dot Al2O3 center dot 2SiO(2)), kalsilite (K2O center dot Al2O3 center dot 2SiO(2)), leucite (K2O center dot Al2O3 center dot 4SiO(2)) and potassium beta-alumina (K2O center dot 11Al(2)O(3)) were formed as a consequence of reactions between alkali and the bricks.