Corrosion of MgO–C Refractory with Ladle Slags

Herein, MgO–C refractory brick is immersed into the molten ladle slags with various CaO/Al 2 O 3 ratios (located in the range of 0.56–0.78 and 1.99–1.36) and SiO 2 addition from 1 to 20 wt%, at two temperatures of 1550 and 1650 °C. After the interaction with the slag with a CaO/Al 2 O 3 ratio range of 0.56–0.78, the MgAl 2 O 4 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 MgAl 2 O 4 on the interface of MgO–C brick is observed. For the slag with the CaO/Al 2 O 3 ratio range of 1.99–1.36, a small amount of minor size of MgAl 2 O 4 particle is detected only with 20 wt% of SiO 2 addition. Instead of a formation of the MgAl 2 O 4 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/Al 2 O 3 ratio and is enhanced via the addition of SiO 2 along with the increased solubility of MgO. The increased solubility of MgO in the slag with increasing SiO 2 has also been predicted via FactSage.