Analysis of interfacial area changes during spontaneous emulsification of metal droplets in slag

In some metal/slag reactions involving spontaneous emulsification, there is a significant increase of interfacial area, which in turn affects the global rate. In previous work by the authors, the reaction between Fe-Al alloy droplets and CaO-SiO2-Al2O3 slag was investigated. Re-evaluation of the data has shown that at an initial reaction rate above 9 × 10−7 mol min−1 mm−2, the maximum change in interfacial area increases linearly with the initial rate and with the change of free energy due to chemical reaction. There were found to be two sources of interfacial area increase: (a) flattening of the original droplet, which was independent of initial rate; and (b) separation of smaller droplets, which was dependent on the initial rate.