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

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.