ESTIMATION OF HYDROXYL CAPACITY OF MOLTEN SLAGS BY CELL MODEL

A statistical thermodynamic model, cell model, has been attempted to r epresent the hydroxyl capacities of some molten silicates and molten a luminates. The slag systems discussed were CaO-SiO2, CaO-Al2O3 binarie s and CaO-SiO2-MgO, CaO-Al2O3-MgO and CaO-SiO2-Al2O3 ternaries. The ce ll model is based on the description of the liquid in terms of cells c omposed of an oxygen anion surrounded by two cations (i, j). In additi on to binary parameters, W-ij and E(ij) a new parameter, W'(Hi) was in troduced into the cell model for representing the hydroxyl capacity. H ere, W'(HI) is free energy of formation of dilute H-O-i cell. The hydr oxyl capacities calculated by the model agreed with the experimental d ata over the wide range of slag composition and temperature. A good co rrelation between W'(Hi) and free energy of formation of hydroxide was confirmed. Therefore, the cell model with the new parameter W'(Hi) is considered to be applicable to predict the hydroxyl capacities of mul ticomponent slags.