2017 Volume 57 Issue 10 Pages 1698-1702
In the steel refining process, dissolution of quick-lime would accompany the formation of 2CaO·SiO2 on its surface. For proper understanding of heat supply to the lime phase from the molten slag through this 2CaO·SiO2 layer, thermal conductivity of this phase should be well known. The present study investigates the thermal conductivity of 2CaO·SiO2 bearing solid solution by hot-wire and hot-strip methods. Thermal conductivity of the solid solution was obtained to have the value from 0.28 to 1.18 W/m·K at temperatures from 298 to 1623 K and found much smaller than that of CaO. Its temperature dependence was positive as is often characterized for complex oxide system. Addition of FeO as solid solution component to 2CaO·SiO2 phase raised thermal conductivity and effect of change in concentration of P2O5 was also elucidated to have a minimum peak of thermal conductivity appearing with this change. On the basis of the thermal conductivity of 2CaO·SiO2 obtained and that of CaO, thermal behavior of practical process has been evaluated. The complete thermal decomposition time of CaCO3 contained by 4 mass% in the sphere of quick lime having the radius of 1 cm is estimated to be about 30 s. The appropriate control of residual ratio of CaCO3 and size of quick-lime would be necessary for the promotion of lime dissolution into the steelmaking slag.