Effect of MgO on Evolution of Interface Structure between Low-Basicity Refining Slag and MgO-C Refractory

MgO-C bricks are widely used as a refractory lining in the slag line part of the ladle of a cord steel refining. The dissolution of their main component MgO into the refining slag is one of the main reasons for their shortened service durability. Laboratory experiments are carried out using low-alkalinity refining slag and unaltered MgO-C bricks by static crucible method. Physicochemical analysis, FactSage thermodynamic calculations, etc., are performed on the specimens, and the dissolution mechanism of magnesia is investigated. When the low-melting-point-phase CaMgSiO4 (CMS) decomposes at high temperatures, the concentration and activity of (MgO) at the local interface between slag and MgO-C brick increase rapidly, inhibiting the dissolution of magnesia into slag at the CMS in situ. The rapid weakening of the dissolution drive of the slag to the magnesia corrosion occurs when the MgO content in the refining slag approaches saturation. To verify the feasibility of extending the service life of MgO-C bricks at the refining ladle slag line, the study involves controlling the MgO content in the refining slag.