Impact of antioxidants in MgO–C refractory on steel cleanliness and refractory degradation

Abstract

Magnesia-carbon (MgO–C) refractories are used in steelmaking processes as lining materials. We performed lab-scale tests at 1600 °C and a pO2 of 10−15 atm to determine the effect of Al and Si antioxidant level, time and slag composition on the amount and nature of inclusions in the steel and on the corrosion and infiltration of the refractory. In all steel samples, a pick-up of Al, Si and C was observed. For the refractories containing antioxidants, longer holding times seem to increase the number density of inclusions, especially in combination with a slag with lower MgO content. For the given experiments, the beneficial role of antioxidants against slag corrosion was not observed, possibly due to the low pO2, which prevented C oxidation. As both MgAl2O4 and SiC, formed in the refractory, react and dissolve in the slag infiltrating in the refractory, they do not play a protective role.