A manganese distribution prediction model for CaO–SiO2–FeO–MgO–MnO–Al2O3 slags based on IMCT

Abstract

A thermodynamic model for predicting manganese distribution ratio LMn and manganese capacity CMn of CaO–SiO2–FeO–MgO–MnO–Al2O3 slags, i.e. IMCT-LMn and IMCT-CMn models, has been developed by using a thermodynamic model for calculating mass action concentration of ion couples or structural units in the slags based on the ion–molecule coexistence theory (IMCT). The developed IMCT-LMn and IMCT-CMn models have been verified with the experiment results of CaO–SiO2–FeO–MgO–MnO–Al2O3, CaO–SiO2–MgO–FeO–Fe2O3–MnO–P2O5, CaO–SiO2–MgO–FeO–Fe2O3–MnO–Al2O3–P2O5 slags reported by different researchers, a total of 200 industrial measurements with large compositional variations and predicted results by summarised five LMn models and two CMn models. The developed thermodynamic model for calculating manganese distribution ratio can determine quantitatively the respective manganese distribution ratio LMn,i and the respective manganese capacity CMn,i of four demanganisation products as MnO, MnO.SiO2, 2MnO.SiO2 and MnO.Al2O3. A significant difference of demanganisation abilities among FeO, FeO + Al2O3 and FeO + SiO2 can be found as 98, 1.8 and 0.2%. By comparing binary and complex basicity, the optical basicity is recommended to describe the relationship between basicity and manganese distribution ratio. With the aid of the current model, the co-effects of the NFeO/ NMnO ratio and optical basicity on the LMn and CMn of CaO–SiO2–FeO–MgO–MnO–Al2O3 slags are investigated.