China's Refractories

Abstract:

A ladle primarily is a container used to transport molten steel from the steelmaking unit to the casting facility. The essential requirements are heat resistant, insulative and strong enough to hold molten steel up to 300 t, with a structure of multilayered refractory lining in a steel shell vessel. When a ladle is assembled with three-phase graphite electrodes, a ladle furnace forms, starting steel refining process with/without the vacuum tank degasser and RH circulating degasser, in order to meet the growing demand on high purity and higher quality steel. The working lining is under aggressive conditions that comprise the chemical reaction with molten steel, the severe corrosion of liquid slag, the disaggregation through oxidation, and the strong stress due to the impacting of the melts and gases and the effects of thermomechanical behaviors. Magnesia-carbon brick is one of the major materials, being indispensable for the slagline of a ladle furnace. Alumina-magnesia-carbon brick has played an important role to substantially increase the service life in the metal zone, from the early lining materials of high alumina and doloma bricks. The permanent lining must assume sufficient responsibility to allow finishing the process of the engaged charge in case of a failure in the working lining. The insulation layer must be as thin as possible in order to maximize the ladle’s capacity, and reduce the shell temperature for saving energy. In this issue, several integrant refractories are reviewed or investigated in order to compile a lining overview, and to contribute a prolonged service life under aggressive working conditions of the ladle furnace.

Key words: ladle furnace, steel refining, ladle cycle, ladle lining, temperature gradient