Formation and Prevention of Nozzle Clogging during the Continuous Casting of Steels: A Review

Nozzle clogging is a common phenomenon in the continuous casting of steels, especially for aluminum killed steels, and has detrimental effects on the continuity of casting and the steel cleanliness. The formation and prevention of nozzle clogging during the continuous casting of steels was reviewed in the current study. The characterization of nozzle clogging was firstly summarized, finding that the composition, morphology, and structure of the nozzle clogging significantly depended on the steel grade, casting condition, and clogging degree. Then three factors affecting the formation of nozzle clogging was briefly summarized as the physical adhesion of high-melting-point inclusions, the temperature drop resulted from the insufficient preheating of nozzles and the temperature fluctuation of molten steel, and the chemical reactions occur during the continuous casting. The prevention methods of nozzle clogging could be roughly divided into 5 types, including the cleanliness improvement of steel, the liquid modification of inclusions, the fluid flow control inside the nozzle, the coating treatment on the inner surface of nozzles, and the external field treatment. Moreover, the challenge of the nozzle clogging control in the future was proposed. Multiple methods should be coordinated, especially the external field treatment should be developed to achieve a better inhibitory effect on the nozzle clogging.