The conductivity and the crystallization of perovskite (CaTiO3) from Ti-bearing blast furnace slag studied by A. C. impedance method

The conductivities of a Ti-bearing blast furnace slag (with 23% TiO2) and t he synthetic slag consisting of CaO-SiO2-Al2O3-TiO2-MgO were measured accur ately 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 : In kappa = 14.212 - 24 820/T for the Ti-bearing blast furnace slag and In kappa = 8.557 - 15 860/T for the synthetic slag(unit of kappa: Omega(-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 tempe rature at which CaTiO3 started to crystallize was determined as 1 693 K. Ra te constants and activation energy for the formation reaction of CaTiO3 wer e 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 o f the slag. The rate constants and the activation energy for the dissociati on reactions were also calculated.