| The refractory samples from the steel ladle of 300 ton capacity, POSCO, have been recovered from a joint between MgO bricks and Al₂O₃-MgO castable, from the castable wall for slag removal and steel tapping and from the bottom of ladle. The samples were cut into thin sections and then observed under optical microscope, by means of X-ray diffraction and electron optics. The slag penetration into ladle wall, a portion of which serves as a trough for slag removal, is far deeper than that for steel tapping. This controls the ladle lining life. For balanced wear, the trough may be replaced by MgO bricks which is more slag resistance than the castable. This will increase ladle lining life. Al₂O₃ in the slag represented by tricalcium aluminate reacts with MgO in bricks to form MgAl₂O₄ and the reaction between the remaining CaO and MgO forms eutectic at 2300℃. But the reaction between CaO in slag and Al₂O₃ in castable makes low-melting calcium aluminates such as CaO·Al₂O₃ and CaO·2Al₂O₃. As a result, MgO bricks have higher slag resistance than the castable. |
|
