Abstract

The corrosion of high purity MgO refractories from molten iron-rich OBM converter slag has been investigated by performing experiments in an electric laboratory furnace. Corrosion tests were conducted at 1600 – 1650oC for 1, 2 or 4 hours. Following lab experiments, the mineralogical phases of MgO refractories, slags and the intermediate infiltration zone were identified by SEM/EDS. It has been shown that Fe infiltrates and replaces Mg in MgO refractories, thus forming magnesiowustite ((Mg,Fe)O). The maximum depth of the slag infiltration zone was estimated to 1.31 mm in the laboratory test where slag was in contact with the refractory for 4 h, at 1650⁰ C Thermodynamic modeling of the slag and refractories equilibrium conducted with FactSage 7.0, confirmed the formation of magnesiowustite in the intermediate zone, with progressively higher substitution rate of Mg by Fe. This increasing substitution results in a decrease of the melting point of magnesiowustite, thus causing the collapse of the refractories even at temperatures lower than the operational temperature.