The use of ladle refers to ensuring that there will be no accidents such as ladle burnout, ladle shell softening, and ladle falling during the designed service life of the ladle lining. When considering the use of ladle, its service life should be considered first, that is, to ensure that the surface temperature of the cladding is less than the creep temperature of the cladding material during the service life of the lining, which should generally be less than 300~350℃ (the creep temperature of carbon steel is 300~350℃, and the creep temperature of alloy steel is 350~400℃).
Selecting refractory bricks for ladle lining is a critical task because it directly affects the service life of the ladle, the efficiency of the steelmaking process, and the quality of molten steel. The selection of refractory materials for ladle lining is mainly based on the use conditions of the ladle, such as the temperature of the molten steel, chemical composition, operation mode, and economic factors. The following is a detailed description of the selection of refractory materials for ladle lining:
1. Lining structure
The lining of the ladle is usually composed of a working layer, a permanent layer, and an insulating layer: the working layer is in direct contact with the molten steel and is mainly subjected to high temperature and chemical erosion. The permanent layer is behind the working layer, providing certain support and heat-resistant protection. The insulation layer is on the outer layer to reduce heat loss.
2. Common lining materials and their characteristics
Magnesium carbon brick composition: magnesia (MgO) and carbon (C). It has high refractoriness, high thermal shock stability and slag erosion resistance. It is used for ladles that require high slag erosion resistance and thermal shock stability, such as ordinary steelmaking and clean steel production.
Aluminum magnesium carbon refractory bricks composition bauxite (Al₂O₃), magnesia (MgO) and carbon (C). It has the advantages of magnesium carbon bricks and high alumina bricks, good thermal shock stability and strong oxidation resistance. It is suitable for ladles that require good slag erosion resistance and thermal shock resistance.
High alumina bricks contain bauxite with a higher aluminum content. High refractoriness, good mechanical strength, but poor slag erosion resistance. It is suitable for ordinary ladles, especially for alkaline or weakly acidic slag environments.
Magnesium spinel brick is alumina spinel (MgAl₂O₄) formed by bauxite and magnesia. It has good slag erosion resistance, thermal shock resistance and structural strength. It is suitable for clean steel production and demanding steelmaking processes.
Zircon refractory bricks is mainly composed of zirconium oxide (ZrO₂). It is resistant to high temperatures and chemical erosion, but the price is relatively high. It is used in special steel production or ladles under high temperature conditions.
Casting materials and spray coatings contain bauxite, magnesia and binders. It is easy to construct and can form seamless linings to reduce structural defects. It is used to repair or construct linings with complex shapes.
