In the ladle, due to the complex physical and chemical environment at the slag line, the furnace lining at this part is most vulnerable to damage. The chemical attack of slag on magnesia-carbon bricks is mainly through the dissolution of magnesia and the oxidation of carbon in the matrix of magnesia-carbon bricks, and the damage of magnesia-carbon bricks is caused by the combined action of the following factors:
1. Effect of basicity: The lower the basicity of the slag, the more favorable the erosion of magnesia-carbon bricks. If the basicity of the slag increases, the activity of SiO2 in the slag will decrease, which can reduce the oxidation of carbon. With the increase of temperature, the activity of FeO in the slag decreases, which relatively slows down the erosion behavior of the slag on magnesia-carbon bricks;
2. Influence of MgO: Osbom et al. found that the content of MgO in the slag layer was as high as 30% when they analyzed the composition of the LF slag line. The higher the value, the slower the erosion of slag on magnesia-carbon bricks.
3. Influence of Al2O3: Al2O3 in the slag will reduce the melting point and viscosity of the slag, increase the wettability of the slag and the refractory material, make the slag more easily penetrate from the magnesia grain boundary, and make the periclase separate from the magnesia-carbon brick matrix .
4. Influence of FeO: First, FeO in the slag is easily oxidized with graphite in the magnesia-carbon brick at high temperature, and produces bright white iron beads, forming a decarburized layer as shown in Figure 1, followed by the square magnesia in the magnesia-carbon brick Stone will also react with FeO in the slag to form low melting point products.