Dissolution kinetics and reaction mechanism of Al2O3 in molten CaF2–CaO–Al2O3 slag

The dissolution behavior of Al2O3 in molten CaF2–CaO–Al2O3 slag, a basic slag system of electroslag remelting process, was investigated by rotating cylinder method using corundum rods to simulate Al2O3 inclusions in steel. The experimental results show that the dissolution rate of Al2O3 rods in CaF2–CaO–Al2O3 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 Al2O3 in CaF2–CaO–Al2O3 slag increases with the increase in the ratio of CaO to Al2O3, 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 Al2O3 in slag C is calculated to be 222.86 kJ mol−1. During the dissolution of Al2O3 inclusions in the slag, it reacts with F− in liquid slag at first, then reacts with CaO to form the intermediate compounds of xCaO–yAl2O3 system, and finally dissolves in molten slag. The dissolution rate of Al2O3 inclusions in CaF2–CaO–Al2O3 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.