The role of tundish was originally to function as a steel reservoir after the ladle and a distributor into continuous casting moulds. It was designed to obtain proper steel flow pattern through the tundish and to keep thermal losses inside certain limits. When production of “clean” steels with high requirements for oxide inclusions was developed by applying sophisticated secondary steelmaking treatments in the ladle the role of tundish became more critical. It became essential to maintain or even to improve the level of the steel cleanliness by minimizing contamination of steel with air, slag or refractory materials between ladle and the casting moulds. According to a novel principle of clean steel production the main function of tundish is to maintain the level of cleanliness attained in the ladle by minimizing harmful contamination of steel with air, slag or refractory materials from ladle to moulds. This could be called a “protective or inert tundish practice”. As a consequence, the function of tundish slag is a barrier against reoxidation and thermal losses. By reconstructing tundish to a closed chamber with lid, argon gas shrouding and eventual heating system, tundish slag might be even ignored.
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