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Slag corrosion on magnesia carbon bricks[06/28/2021]
In the ladle, due to the complex physical and chemical environment at the slag line, the furnace lining is the most vulnerable to damage. The chemical attack of steel slag on the magnesia carbon brick is mainly through the dissolution of magnesia and the oxidation of the graphite in the brick body. Under the combined action of the two factors, the MgO-C Brick is damaged.
1.The effect of alkalinity: the lower the alkalinity of the slag, the more beneficial it is to the erosion of the MgO-C Bricks. The increase of the alkalinity of the slag will reduce the activity of FeO in the slag, and the decrease of the activity of FeO will lead to the diffusion capacity of FeO.
2.The influence of MgO: Osbom et al. found that the MgO content in the reaction layer of the residual fire bricks of the LF slag line is very high. When the MgO content in the slag is low, it will affect the magnesia carbon brick. The erosion rate of bricks is very large, and the lower the alkalinity, the faster the erosion of magnesia carbon bricks.
3.The influence of Al2O3: Al2O3 in the slag will reduce the melting point and viscosity of the slag, which greatly increases the penetration and erosion of the magnesia carbon brick by the slag, and can also corrode the magnesia from the magnesia grain boundary, making periclase Dissociate.
4. The influence of FeO: First, the FeO in the slag can easily react with the graphite in the MgO-C Brick at high temperature, and produce bright white iron beads to form a decarburized layer as shown in Figure 1. Secondly, the magnesia will interact with the graphite in the slag. FeO will form a low melting point of rich magnesium body. AT&S believes that in the process of repeated heating and cooling of the ladle, the phase transformation between the magnesium richite and the mafic ore is accompanied by the volume change, which causes cracks in the magnesia on the working surface, which in turn leads to the formation of magnesia. Dissolution, foreign studies believe that the increase in iron content in steel slag is detrimental to the life of magnesia-carbon bricks. Firstly, iron oxides accelerate the oxidation of graphite, and secondly, it increases the solubility of MgO in the slag and accelerates the dissolution of periclase. The combined effect of the two is the erosion of magnesia carbon bricks