Configuration of refractory for ladle furnace
The ladle furnace is called LF furnace, which is the most widely used refining equipment outside the furnace. The LF furnace strengthens the thermodynamic and kinetic conditions of the metallurgical reaction by means of arc heating, reduction atmosphere in the furnace, white slag refining, and gas stirring, so that the molten steel can achieve refining effects such as deoxidation, desulfurization, alloying, and heating in a short time. To ensure that the molten steel composition 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 multiple furnaces continuous casting.
In recent years, the LF furnace is the most widely used device for secondary refining at home and abroad. The basic trend of the refractory materials used is the alkalinization and irregularity of the ladle material to increase the service life of the ladle and reduce the consumption of refractory materials.
(1) Refractory for slag line
The LF slag line area is under high alkalinity slag and high stress conditions, and the damage is very serious. Therefore, many high-quality magnesia-carbon bricks that are resistant to erosion and thermal shock are used.
(2) Refractory for furnace wall
High-aluminum brick is generally used for the LF furnace wall. However, although the traditional high-alumina brick has good corrosion resistance, the slag penetration is serious, which causes the structure to peel off and the durability is unstable. In addition, the slag infiltration site shrinks and cracks are generated, resulting in damage. Generally, carbon and MgO materials need to be added to overcome. Refining furnace linings have evolved from shaped products to amorphous shapes. Materials include magnesium carbon, aluminum magnesium carbon, and aluminum-spinel castables. Magnesium-calcium-based materials are also the development direction. The LF furnace uses different grades of magnesium-carbon bricks and magnesium-aluminum-carbon bricks or aluminum-magnesium-carbon bricks for comprehensive masonry lining, which has better benefits.
(3) Refractory for furnace cover
The lid of the LF refining furnace uses castables. The furnace cover castables developed by Luo Naiyuan and other institutes use fused corundum and Yangquan special grade alumina as the main raw materials, pure calcium aluminate cement (4% -8%) as the binder, and (8% -12%) added Silica and alumina ultrafine powder, small amount of additives and high-efficiency water reducing agent, make the castable meet the requirements of thermal shock resistance and spalling resistance.
(4) Refractory for bottom and ventilated brick
Large LF furnace bottom cast large brick, the main composition is Al2O3-MgO.Al2O3, good permeability resistance. The bottom of the LF furnace is also made of dry calcium ramming material