The main reasons for the blockage of aluminum-carbon submerged nozzle are as follows:
(1) SiO2, Fe203 in the nozzle and [A1] and [Ti] in the molten steel generate netlike Al2O3 or high melting point materials containing Ti, which adhere to the inner wall of the nozzle and cause the nozzle to be blocked.
(2) SiO2 and Al2O3 in the material are reduced by graphite, and react with [A1] and [O] in the molten steel to form floccent or powdered Al2O3, making the water mouth blocked.
(3) the aluminum-carbon immersion nozzle has good thermal conductivity, which makes the temperature difference between the inner wall of the nozzle and the steel interface and easy to cause the deposition of Al2O3.
(4) the deoxidized product Al2O3 in the molten steel is easily attached to the alumina aggregate on the inner surface of the nozzle.
At present, the main methods to prevent the blockage of aluminum-carbon submerged nozzle are as follows:
(1) solve the problem of liquid steel plug from the materialA lot of research work has been done on the methods to prevent the water mouth from clogging. At present, in the prevention of water mouth jam, the research of anti-blocking materials, such as the use of CaO containing high materials for the immersion nozzle, also used ZrO2 a C, BN - C, N4Si - C, Zr02 a BN - C and other materials, have achieved some results, has entered industrial applications in China.
(2) starting from the structure of the nozzle to prevent the blockage of the nozzleAt present, one of the most common methods is to place an argon blowing slit on the inner wall of the immersion nozzle and blow argon into the inner wall of the nozzle through the slit to form an air film on the inner wall to prevent the nozzle from being blocked.
(3) wear a fire-resistant fiber jacket to the immersion nozzleIn order to reduce the thermal conductivity of the aluminum-carbon immersion nozzle, the surface of the nozzle is wrapped with a layer of fire-resistant fiber to improve the thermal insulation of the nozzle and prevent the blockage of the nozzle.