Thermal Conductivity of 2CaO·SiO₂ Bearing Solid Solution

抄録

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.