The aluminum coal zirconium nature plunges the type drainage opening to use between the middle package and the crystallizer steel class protection casting, fills the stick coordination use with the whole to be possible to control the steel class speed of flow, shields the steel class and adjusts the steel class direction. The product has the good heat-resistant knocking stability and the inoxidizability as well as the anti-machinery break. After each batch of products undergo the strict lossless crack detection examination, leaves the plant