In order to effectively and economically smelt high-quality steel, oxygen converters and electric furnaces become containers for preliminary decarburization, heating and melting scrap steel or smelting some ordinary steel, and the refining of molten steel is transferred to the ladle. There are many types and methods of refining outside the furnace, mainly VOD, AOD, VAD or RH, LF, LF-VD, CAS, etc. The purpose of refining outside the furnace is mainly to homogenize the composition and temperature of molten steel, remove inclusions in molten steel, etc. With the diversification of molten steel refining methods, the working conditions of refractory materials for ladle lining are becoming more and more harsh, and its development has also gone through a long process. At present, the development of the steel industry is relatively sluggish. On the premise of adapting to the current situation, it is necessary to develop energy-saving, environmentally friendly, high-quality and efficient refractory materials for ladle lining.
Requirements for refractory materials for ladle lining
1. Thermal shock resistance
Ladles are operated intermittently. During the various stages of the ladle's use, its internal temperature changes in a wide range. During the drastic temperature changes inside the ladle, its lining refractory materials are required to have no cracks and good thermal shock resistance.
2. Slag erosion resistance
During the ladle continuous casting process, the slag layer on the molten steel surface gradually decreases as the molten steel flows out from the bottom of the ladle. The refractory materials of the ladle lining are in contact with the slag for a long time, so they are required to have good slag erosion resistance.
3. Scouring resistance
During the process of molten steel refining, the molten steel forms a huge vortex inside the ladle, which severely scours the refractory materials of the ladle lining, so they are required to have good scouring resistance.
Development direction of refractory materials for refined ladle lining
1. Aluminum-magnesium castable
Based on the current research on aluminum-magnesium castables, by optimizing the particle grading, adding appropriate particle size and appropriate amount of fused magnesia sand, it can generate magnesium-aluminum spinel in situ at high temperature, and enhance the thermal shock resistance and erosion resistance of the ladle lining under the action of micro-expansion. At the same time, by adjusting the formula and construction process, the explosion phenomenon after the overall pouring is prevented.
2. MgO-CaO castable
In order to better remove inclusions in molten steel, calcium-containing refractory materials have gradually attracted widespread attention at home and abroad. On the basis of MgO-CaO bricks, MgO-CaO castables are obtained by pre-treating MgO-CaO sand, such as high-temperature sintering, surface treatment, introduction of additives, etc., and measures such as brushing slurry on its surface or sealing packaging can significantly reduce its hydration during transportation and storage.
Comprehensive consideration should be given to factors such as ladle capacity, smelting steel type, actual operating conditions, etc., and different ladle lining refractory materials should be selected while ensuring the service life of the ladle to maximize the service life of the ladle and reduce steelmaking costs.
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