VOD process, also known as vacuum oxygen decarburization, is used for refining ultra-low carbon steel. The refining temperature of VOD is high, up to 1800t, with a general fluctuation of 1640~1750 Celsius. Slag from acidic to alkaline slag fluctuates in a large range, and the alkalinity varies from 0. 3 to 2. 0, mainly acidic slag. The low alkalinity slag has good fluidity and stays at high temperature for a long time. Oxygen blowing decarburization is rapid, oxygen blowing decarburization period accounts for 80% of the blowing period, and the acid slag refining time is long at high temperature, which aggravates the damage of refractory materials. Strong stirring, by blowing oxygen caused by the carbon and oxygen reaction, produce a large number of gas, so that the steel heated boiling, serious scouring furnace lining; In vacuum operation, the vacuum degree is as high as about 100Pa, resulting in the volatilization of some components in the brick, and the infiltration of molten steel and slag into the brick, and gradually react with it, resulting in the brick organization loose cracking; VOD clearance operation leads to the next cycle after the finished casting of refined steel, resulting in large temperature changes and frequent thermal shock action of the ladle.
According to the working conditions of VOD furnace, the refractory materials should meet the following requirements. Under the condition of high temperature and vacuum, the volume stability is better, and the mineral composition of refractory should effectively resist the vacuum reduction reaction and avoid the deterioration of the tissue. Under the conditions of high temperature, oxygen blowing, rapid decarburization and boiling of molten steel, refractory materials should effectively resist steel slag erosion and steel erosion. VOD refractories should have good thermal shock resistance in order to meet the requirements of corrosion resistance.
In order to avoid the use of refractory in the process of structural peeling and thermal peeling. The refractories for VOD furnace are mainly fired magnesia chrome brick, directly bonded magnesia chrome brick and magnesia calcium brick, mainly magnesia chrome brick.