Experimental Investigation of Relationship between Enthalpy Change and Viscosity in Blast Furnace Type Slags

Abstract

The effects of MgO, Al₂O₃ and basicity on the heat capacity and enthalpy change of CaO–SiO₂–MgO–Al₂O₃ slags at 1673 K and 1773 K as well as the thermal stability were investigated. The enthalpy change at 1773 K increased with the addition of Al₂O₃ and MgO, but decreased with increasing basicity. Thus, the higher basicity helped to reduce the heat consumption and fuel ratio of blast furnace. With increasing MgO content, the fluctuations of the temperature and viscosity caused by the reduction of the slag heat quantity decreased. Furthermore, the slag will have a better fluidity and thermal stability when MgO content is greater than 8 mass%. The increase of Al₂O₃ content deteriorated the fluidity and thermal stability of the slag to some extent. When the reduction of the slag heat quantity was fixed, as the basicity increased, the slag temperature increased obviously and the viscosity significantly decreased. Also, the fluctuations of slag temperature and viscosity became less pronounced with increasing basicity. The increase of the basicity was favorable to improve the fluidity and thermal stability of the slag. For the slag system of this experiment, the suitable basicity was 1.10–1.15.