Corrosion of MgO-C Refractory with Ladle Slags

Herein, MgO-C refractory brick is immersed into the molten ladle slags with various CaO/Al2O3 ratios (located in the range of 0.56-0.78 and 1.99-1.36) and SiO2 addition from 1 to 20 wt%, at two temperatures of 1550 and 1650 degrees C. After the interaction with the slag with a CaO/Al2O3 ratio range of 0.56-0.78, the MgAl2O4 phase with various sizes is found to form in the solidified slag layer adhering to the MgO-C sample surface, and a layer consisting of MgAl2O4 on the interface of MgO-C brick is observed. For the slag with the CaO/Al2O3 ratio range of 1.99-1.36, a small amount of minor size of MgAl2O4 particle is detected only with 20 wt% of SiO2 addition. Instead of a formation of the MgAl2O4 layer, the Fe phase containing Mn, metallic Ti, and Si is scattered on the side of the solidified slag layer. The corrosion is more pronounced in the slag with a high CaO/Al2O3 ratio and is enhanced via the addition of SiO2 along with the increased solubility of MgO. The increased solubility of MgO in the slag with increasing SiO2 has also been predicted via FactSage.