Dissolution kinetics and reaction mechanism of Al 2 O 3 in molten CaF 2 –CaO–Al 2 O 3 slag

The dissolution behavior of Al 2 O 3 in molten CaF 2 –CaO–Al 2 O 3 slag, a basic slag system of electroslag remelting process, was investigated by rotating cylinder method using corundum rods to simulate Al 2 O 3 inclusions in steel. The experimental results show that the dissolution rate of Al 2 O 3 rods in CaF 2 –CaO–Al 2 O 3 slag increases with the increase in rotating speed and temperature, and the rate-controlling step is the mass transfer in the slag. The dissolution rate of Al 2 O 3 in CaF 2 –CaO–Al 2 O 3 slag increases with the increase in the ratio of CaO to Al 2 O 3 , which is due to the increase in dissolution driving force and the decrease in slag viscosity. The apparent activation energy of the mass transfer of Al 2 O 3 in slag C is calculated to be 222.86 kJ mol −1 . During the dissolution of Al 2 O 3 inclusions in the slag, it reacts with F − in liquid slag at first, then reacts with CaO to form the intermediate compounds of x CaO– y Al 2 O 3 system, and finally dissolves in molten slag. The dissolution rate of Al 2 O 3 inclusions in CaF 2 –CaO–Al 2 O 3 slag for electroslag remelting is positively correlated with the ratio of the dissolution driving force and slag viscosity, and the correlation coefficient is 2.487 × 10 −11 .