Decarburisation behaviour of high-carbon MgO-C refractories in O2-CO2 oxidising atmospheres

Abstract High-carbon MgO-C refractories have been widely used in oxygen bottom blowing converters due to their excellent thermal shock resistance property. However, decarburisation is unavoidable in MgO-C refractory materials applied around oxygen bottom blowing tuyeres. To alleviate the decarburisation rate of MgO-C refractories and prolong the furnace life of oxygen bottom blowing converters, a new method consisting of mixing CO2 in the bottom blowing oxygen was proposed by the authors. The decarburisation behaviour of MgO-C refractories in O2-CO2 oxidising atmosphere has not been studied before. Herein, the effects of the CO2 ratio in the O2-CO2 oxidising atmosphere on the decarburisation amount and the microstructure of the decarburisation zone were investigated experimentally. The results show that as the CO2 ratio increases, the weight loss of the MgO-C refractory decreases with a parabolic trend and the decarburisation zone depth decreases with a linear trend. Micrographs show that pores form in the decarburisation zone, and the amount of pores decreases as the CO2 ratio increases. The results confirm that mixing CO2 in the bottom blowing oxygen can effectively alleviate the decarburisation of MgO-C refractories.