The Conductivity and the Crystallization of Perovskite (CaTiO₃) from Ti-bearing Blast Furnace Slag Studied by A. C. Impedance Method

抄録

The conductivities of a Ti-bearing blast furnace slag (with 23 % TiO₂) and the synthetic slag consisting of CaO-SiO₂-Al₂O₃-TiO₂-MgO were measured accurately in the temperature range of 1 653-1 733 K by A. C. impedance method. The relationships between the conductivity and temperature were obtained as: lnκ=14.212-24 820/T for the Ti-bearing blast furnace slag and lnκ=8.557-15 860/T for the synthetic slag(unit of κ: Ω^-1·cm^-1) in the temperature range of 1 703-1 733 K. Perovskite phase (CaTiO₃) could precipitate from these slags during slag cooling process. The temperature at which CaTiO₃ started to crystallize was determined as 1 693 K. Rate constants and activation energy for the formation reaction of CaTiO₃ were calculated based on the data of conductivity and the first order kinetic equation. Dissociation reactions of Al₂O₃ and TiO₂ could take place due to the crystallization of perovskite phase and the variation of the basicity of the slag. The rate constants and the activation energy for the dissociation reactions were also calculated.