During the pouring process, the nozzle of the intermediate tank or the submerged nozzle may become clogged due to nodulation, with mild cases requiring oxygen burning and severe cases causing interruption of pouring. There are two reasons for the clogging of the water inlet: firstly, the water inlet is frozen. The reason is that the temperature of the molten steel is low or the nozzle is not properly baked, causing the molten steel to condense at the nozzle. The second reason is that there are attached sediments on the inner wall of the nozzle, which causes the nozzle to be narrow or even blocked, especially when pouring swiss machining aluminum killed steel. Analysis of the blockage at the water inlet reveals that its main composition is a mixture of Al2O3 with a glass phase and metallic iron as the main component. Al2O3 has a melting point of 2050 ℃ and exists as a solid particle in molten steel. As the steel flows through the nozzle, the solid Al2O3 will gradually deposit on the nozzle wall. There are four sources of Al2O3 inclusions in molten steel: aluminum deoxygenation products; The product of the reaction between aluminum in molten steel and SiO2 in the nozzle wall; The product of secondary oxidation between oxygen in the air and sheet metal aluminum in molten steel; The reaction product where the temperature of molten steel decreases and the Al-O equilibrium shifts. It can be said that the blockage of the water inlet is the result of the combined effect of these four phenomena. The measures to prevent clogging of water outlets include: selecting appropriate water outlet materials; Using an air wash nozzle; Blowing argon on the intermediate tank plug rod; Adopting calcium treatment technology and using protective casting.
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