Evaluation of some self-sustained capillary effects taking place in slag at the interface during desulphurization process

In the paper are presented and analyzed some specific problems of instability and of Marangoni convection in desulphurizing slags at 1873.15 K, due to the presence of sulphur, during liquid steel treatments. Starting from the quantity sulphide capacity, a limit of sulphur solubility in a homogeneous liquid slag is established. The thermodynamic effect of sulphur in the slag is evaluated using an enthalpy of interaction of sulphur containing the balance of the partial molar enthalpy of mixing for CaS and CaO. The sulphur effect in slag, on the enhancement of the mass transfer coefficient through the interface is evaluated based on the expression of the concentration coefficient of the surface tension related to the mole fraction, the solutal Marangoni number and of the sulphur mass transfer enhancement parameters. It is concluded that during desulphurization, self-sustained capillary effects are present in slags.