Steel slag crusting prevention modifier for RH vacuum treatment after converter discharging and using method thereof

The invention discloses a steel slag crusting prevention modifier for RH vacuum treatment after converter discharging and a using method of the modifier and belongs to the technical field of steel making. The modifier comprises the chemical components of, by weight, 0-25% of CaO, 0-5% of MgO, 2-12% of SiO2, 40-90% of Al2O3, 0-25% of CaF2, and the balance inevitable impurities. The using method comprises the steps that the modifier is prepared according to the weight percentage of the chemical components at first, and the modifier is added to the bottom of a steel ladle before steel tapping oris added along with steel flow in the steel tapping process or is added to the top of slag and subjected to bottom blowing argon stirring after steel tapping is completed. The modifier and the using method thereof have the advantages that the modifier is low in cost, easy to prepare and good in effect, and the problems that steel slag crusts in the RH treatment process and is unlikely to smelt after crusting are effective