The erosion reaction between refractory materials and slag is a physical and chemical reaction process. Generally include physical and chemical processes such as penetration, dissolution and melt erosion. The damage caused by the chemical reaction is that when the system is trying to reach equilibrium, the corrosive liquid phase continuously dissolves the refractory material until it reaches a saturated state and achieves thermodynamic equilibrium. For molten slag, the diffusion rate, concentration, reaction temperature, viscosity, use atmosphere, etc. of the slag all have an impact on its erosion rate. Chemical corrosion is mainly the reaction between molten slag and the product body, accompanied by the generation of new phases and physical changes in the structure of the product body.
RH refining
In RH refining, the slag is mainly alkaline slag, including oxides such as CaO, FeO, MnO, MgO, A12O3, SiO2, Fe2O3, etc. The slag may also contain a small amount of other types of compounds and even metals, such as fluoride (CaF2 )wait. The main crystal phase of periclase-magnesia spinel material is MgO, which can resist the chemical erosion of slag to a good extent. The main ways of damage to the material by slag are penetration and structural spalling.
The penetration of slag into refractory materials refers to the chemical reaction between the slag and the matrix part at the test temperature. Under the action of temperature gradient, liquid viscosity, etc., it penetrates into the lower temperature parts of the material, thereby changing the internal temperature of the material. Structure and chemical composition.
RH dip tube
Slag can penetrate into refractory materials in three ways.
(1) Penetrate into the refractory material through open pores and cracks.
(2) Penetrate into the refractory material through grain boundaries.
(3) The ions in the slag enter the oxides constituting the refractory material and diffuse into the refractory material through the crystal lattice.
Korgul used the dynamic slag resistance method to test the CMAS slag resistance of corundum spinel refractory materials. It was found that in the initial stage of corrosion, the free calcium oxide in the slag can react with the excess Al2O3 in the refractory material and integrate into the melt. In the slag, the calcium content and aluminum content in the slag increase rapidly and aluminum-calcium compounds precipitate. The aluminum-calcium compounds can continue to react with Al2O3 in the refractory material to form CA6. At the same time, because the spinel in the refractory material can absorb Fe ions and Mn ions in the slag, the Si content in the slag increases, the viscosity of the slag increases, and the penetration slows down.