Thursday, May 23, 2013

Methods of Eliminating the Phenomenon of Ladle Nozzle Clogging

      A ladle nozzle is one of the slide gate ceramic elements. Systematic extension of the length of the steelmaking ladle campaign increases the demands on a ladle nozzle. The ideal solution would be a ladle nozzle which withstands the entire ladle campaign. In addition to thermal stability, ladle nozzles must be characterized by high resistance to corrosion and erosion caused by the flow of steel. An important factor affecting the durability of a ladle nozzle is clogging due to steel deoxidation products deposition in the nozzle channel. The phenomenon of clogging makes it difficult to regulate the rate of steel outflow from the ladle and, in extreme cases, can make the nozzle channel close. Clearing the nozzle by oxygen lancing accelerates its destruction.
Methods to prevent clogging:
 1. Ladle Refining Practice. A vacuum degassing treatment yields better cleanliness than does argon bubbling.
2. Reoxidation Prevention. Submerged ladle-to-tundish pouring, shielded tundish surface, ann leak-tight refractory joints will reduce exposure of the steel to oxygen and thereby improve cleanliness.
 3. Oxygen absorber Prevention.Optimal tundish flow patterns as well as filtration and electromagnetism techniques can remove Oxygen absorber products from the melt.
 4. Flux Enrainment Prevention. Submerged ladle-to-tundish pouring and avoidance of ladle slag carryover will reduce the amount of exogenous inclusions in the melt.

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