Reasons for damage to intermediate frequency furnace lining and how to solve them

During the use of the intermediate frequency furnace, the thickness of the refractory material used for the furnace lining is only 70-110mm.Intermediate frequency furnace liningThe inner side is in contact with the high-temperature molten metal, and the outer side is close to the water-cooled coil. The temperature difference between the inner and outer sides of the refractory material is large, and it is under the operating conditions of relatively thin sections and strong corrosive environments in many smelting operations. The primary process conditions that affect the damage of the furnace lining include: smelting Temperature, degassing time, primary degassing amount, chemical composition of slag and type of steel produced. The primary factors affecting the damage to the lining are: chemical corrosion of slag, structural spalling of refractories and thermal corrosion.

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The lining of the intermediate frequency furnace is usually made of refractory materials of various sizes and sizes (commonly used refractory materials mainly include four categories: magnesia, quartz, aluminum and composite materials).

Its characteristics are: direct bonding. Therefore, it has high corrosion resistance, high mechanical strength and good thermal shock resistance.

2. Damage mechanism of magnesia lining material

Taking magnesia refractories as an example, the damage mechanism of magnesia materials is described:

The main manifestations of the damage of magnesia materials are: thermal erosion caused by flowing molten steel and chemical erosion caused by the penetration of slag components into the material.

During the smelting process, the solution will enter the refractory matrix through the capillary channels in the refractory matrix to corrode the furnace lining. The components entering the refractory matrix include: CaO, SiO2, FeO in the slag; Fe, Si, Ai in the molten steel , Mn, C, and even metal vapor, CO gas, etc. These incoming components are deposited in the refractory capillary channels, forming the discontinuity between the physical and chemical properties of the refractory working surface and the original refractory matrix, and under the sudden change of operating temperature There will be cracks, shedding and loose structure. Strictly speaking, this damage process is much more serious than the dissolution damage process.

The research results show that optimized particle gradation and reasonable structure design of breathable bricks can improve the thermal shock stability and slag resistance of breathable bricks, and then improve their performance. Oxygen cleaning is an important reason for the damage of the breathable brick. By adding silicon nitride, Sialon and other additives in the matrix, the breathable brick has the characteristics of not being wet with molten steel, and the corrosion loss rate is reduced.