In the steelmaking furnace, magnesia-chrome bricks are mainly used to resist the corrosion of high-temperature molten steel and slag. The following are the concrete measures and principles to prevent corrosion of magnesia-chrome bricks in steelmaking furnace:

I. Choosing the Right Brick Type

Directly bonded magnesia-chrome brick: This kind of brick adopts high-purity magnesia and chrome concentrate, and has high high-temperature strength and corrosion resistance after high-temperature firing. Its direct combination rate of high-temperature mineral phase is high, which can effectively resist the chemical erosion of slag.

Fused and recombined magnesia-chrome brick: This kind of brick has stronger corrosion resistance, especially for slag with high CaO/SiO₂ ratio. Its sintering temperature is higher, apparent porosity is lower, and bulk density is higher, which further enhances the corrosion resistance.

II. Optimizing the microstructure of bricks

Formation of secondary spinel: The research shows that the amount and size of secondary spinel in brick have a significant influence on the corrosion resistance of brick. Increasing the amount of secondary spinel (for example, by optimizing raw material ratio and sintering process) can significantly improve the slag resistance and erosion resistance of bricks.

Low porosity and high density: magnesia-chrome bricks with low porosity and high density can effectively prevent the penetration and erosion of slag.

III. Reasonable design of furnace lining structure

Partition use: according to the working conditions of different parts of the steelmaking furnace, different types of magnesia-chrome bricks are reasonably selected. For example, directly bonded magnesia-chrome bricks or fused magnesia-chrome bricks are usually used in the lower part of vacuum chamber and the inner lining of dip tube, which are in direct contact with molten steel and slag.

Design of protective layer: In some parts, erosion can be further reduced by designing protective layer (such as forming a dense oxide layer on the surface of brick).

IV. Control of process conditions

Reduce the corrosiveness of slag: By adjusting the chemical composition of slag (such as reducing the CaO/SiO₂ ratio), the corrosion of slag to magnesia-chrome bricks can be reduced.

Reduce temperature fluctuation: avoid the drastic change of temperature in the furnace to reduce the damage of thermal shock to the brick body.

V. Regular maintenance and inspection

Timely repair: For locally damaged bricks, refractory materials should be used to repair them in time to prevent further erosion.

Monitoring erosion: regularly check the erosion of bricks and replace severely eroded bricks in time.

Through the above measures, magnesia-chrome brick can effectively resist high temperature and chemical erosion in steelmaking furnace, prolong the service life of furnace lining and improve production efficiency.