Study on the Discharging Property of Tundish Slag for an Improved Hot-Tundish Recycling Process

摘要

The slag discharging phenomena was investigated at 1773 K using the lab-scale experimental apparatus simulating the real working tundish. The experiment was performed by varying six major process parameters considered to have a considerable effect on the slag discharging such as basicity ((%CaO)/(%SiO_2)), addition of Fe_tO and CaF_2, substitutions of MgO for CaO and SiO_2 for Al_2O_3, and discharging temperature. With increasing basicity, Fe_tO content and discharging temperature and decreasing Al_2O_3 content, the sticking ratio of slag on Al_2O_3 crucible at the moment of discharging was decreased. While the sticking ratio was increased with the substitution of MgO for CaO by forming MgO·Al_2O_3 spinel in the slag melt, the substitution of Al_2O_3 for SiO_2 has little influence on the sticking tendency because of the identical effects of the two acidic elements. The experimental results were mainly discussed in terms of the viscosity of slag. In most cases the adherence of slag to Al_2O_3 refractory was directly proportional to the viscosity. However, in the case of CaF_2 addition, sticking ratio was constant because the increase in wettability of slag to Al_2O_3 cancelled viscosity decreasing effect.