Ladle Furnace Refractory
Ladle furnace, called LF furnace, is currently the most widely used out-of-furnace refining equipment. The LF furnace strengthens the thermodynamic and kinetic conditions of the metallurgical reaction by means of arc heating, reducing the atmosphere in the furnace, white slag refining, gas stirring, etc., so that the molten steel can achieve deoxidation, desulfurization, alloying, heating, and other refining effects in a short time. Ensure that the composition of molten steel is accurate, the temperature is uniform, and the inclusions are fully floated to purify the molten steel. At the same time, the steelmaking and continuous casting processes are well coordinated to ensure the continuous casting of multiple furnaces.
In recent years, the LF furnace is the most used device for the secondary refining method at home and abroad. The basic trend of the refractory materials used in the ladle furnace is the basicization and amorphization of the ladle material, so as to improve the service life of the ladle and reduce the consumption of the refractory materials of the ladle furnace.
(1) Refractory for slag line
The LF slag line area is under the condition of high basicity slag and high stress, and the damage is very serious. Therefore, more high-quality magnesia-carbon bricks with corrosion resistance and thermal shock resistance are used.
(2) Refractory material for furnace wall
LF furnace walls generally use high alumina bricks. However, although the traditional high-alumina bricks have good corrosion resistance, the slag penetration is serious, causing structural spalling and unstable durability. In addition, the slag penetration part shrinks and causes cracks, resulting in damage. Generally, carbon and MgO materials need to be added to overcome. The lining of refining furnaces has developed from shaped products to amorphous products. From the material, there are magnesium-carbon, aluminum-magnesium-carbon, aluminum-spinel castables, etc., and magnesium-calcium materials are also the development direction. The LF furnace adopts different grades of magnesia-carbon bricks and magnesia-alumina-carbon bricks or aluminum-magnesium-carbon bricks for comprehensive masonry lining, which has better benefits.
(3) Refractory material for furnace cover
Castable is used for the lid of the ladle furnace of the LF refining furnace. The castables for the furnace cover developed by Luo Nai Institute, etc. are made of fused corundum and Yangquan super bauxite as the main raw materials, pure calcium aluminate cement (4%-8%) as a binder, and added (8%-12%) Silica and alumina ultrafine powder and a small number of additives and superplasticizers make the thermal shock resistance and spalling resistance of the castable meet the requirements.
(4) Refractory materials for the bottom of the package and the breathable brick
The large-scale LF ladle bottom ladle furnace is used for pouring large bricks. The main component is Al2O3-MgO.Al2O3 and the permeability are good. The bottom of the LF furnace bag also uses high calcium dry ramming material.