2017 Volume 57 Issue 10 Pages 1703-1709
Rate of 2CaO·SiO2 dissolution into molten CaO–FeO–SiO2 slag saturated with solid iron has been investigated considering the promotion of lime fluxing. A new diffusion couple method has been applied where 2CaO·SiO2 pellet was immersed into molten CaO–FeO–SiO2 slag in an iron crucible, slag convection being suppressed. Concentration profile of components was observed and the diffusion behavior was well understood. Considering the pseudo-binary inter-diffusion between components such as CaO and SiO2 and slag phase matrix, diffusivity of CaO and SiO2 in the present slag has been determined to have the values from 4.9×10−7 to 4.7×10−5 cm2/s at temperatures from 1573 to 1673 K. Assuming the dissolution mechanism as continuous formation and dissolution of 2CaO·SiO2 on the surface of CaO, complete dissolution time into the flowing slag has been estimated on the basis of the Ranz-Marshall empirical equation, and temperature is found to be controlling factor of the dissolution rate in the normal operation condition.