Corrosion mechanism and protection of BOF refractory for high silicon hot metal steelmaking process

Abstract

Corex process can produce hot metal without using coke and has some advantages in reducing pollution. However, the silicon content of hot metal produced by Corex furnace is 0.6–1.5 mass%, which results in the serious corrosion of lining. In order to study the mechanism of lining corrosion, the sample of corrosion lining was taken, and the morphology of the corrosion region was analyzed by SEM. The optimum composition of slag for splashing was determined through a combination of plant experiments and theoretical calculation. The results show that the chemical reaction and the dissolution of (MgO) lead to the lining corrosion of BOF. Concentration gradient of Mg and Fe were found between slag and refractory brick, which promote the mass exchange and reaction between slag and refractory brick. The low basicity of slag leads to low melting point and less formation of solid phase at the same temperature, which result in the scouring down of slag at early stage of steelmaking in BOF. In addition, the low basicity lead to high saturated solubility of (MgO), which is beneficial to the dissolution of (MgO) of refractory lining. The constant reaction and dissolution of (MgO) between lining and slag lead to the lining corrosion. The basicity of slag should be 1.0–1.2. The content of (FeO) should be controlled less than 5 mass%, and the content of (MgO) should be 5–7 mass%.

Keywords

• Lining corrosion
• Refractory dissolution
• Slag attack
• High Si hot metal