On Activity of Iron Oxide in Basic Steelmaking Slags

Studies were made on a calculation method of the iron oxide activity in basic multi-components steelmaking slag. The studies have revealed: 1) Among previously proposed calculation methods, there is no generalized one being capable to calculate the iron oxide activity range of multi-component slag. The methods proposed by ELLIOTT et al and HERAHY-MENKO et al are reliable to calculate the iron oxide activity to some extent and the equilibrium oxygen content in metal can be calculated with a standard deviation of about 200ppm; the oxygen content is in equilibrium with the slag that has a high basicity and (% FetO) of more than 5%. 2) On the assumption that the molten slag dissociates completely to the ionic species, effects of calculation methods of ionic fraction assuming various ionic species of the iron oxide on the iron oxide activity are discussed. As the result, a new calculation method on iron oxide activity has been interoduced by authers log assuming that iron oxide is dissociated to the species Fe2+, Fe3+ and O2-, and utilizing the calculation method on ionic fraction proposed by FLOOD et al. This calculation method is available to determine average oxidation potential of slags. 3) When (CaF2) content is less than 80%, (CaF2) component in the slag increase the iron oxide activity and increase the equilibrium oxygen content in the metal by about 200ppm compared to that in metal, which is equilibrium with the slag free from (CaF2)