Coupling relationship between dephosphorisation and desulphurisation abilities or potentials for CaO-FeO-Fe_2O_3-AI_2O_3-P_2O_5 slags over a large variation range of slag oxidisation ability during secondary refining process of molten steel

摘要

The coupling relationships between dephosphorisation and desulphurisation abilities or potentials for CaO-FeO-Fe_2O_3-AI_2O_3-P_2O_5 slags during secondary refining process of molten steel have been proposed as logL_p + 5logL_s or logC_(PO~(3-)_4)- + logC_(S~(2-) in reducing zone at oxygen potential p_(O_2) less than 2.27x10~(-6)Pa as well as logL_p + logL_s - 5logN_(Fe_tO) or logC_(PO~(3-)_4) + logC_(S~(2-) - log/V_(FeO) in oxidising zone at oxygen potential p_(O_2) greater than 2.27 x 1CT6 Pa through deleting slag oxidisation ability expressed by the comprehensive mass action concentration N_(Fe_tO) of iron oxides based on the ion and molecule coexistence theory (IMCT). The proposed coupling relationships between dephosphorisation and desulphurisation abilities or potentials of the sJags have been verified to be valid using reported data of oxygen, phosphorus and sulphur distribution equilibria between the slags and liquid iron over a temperature range from 1811 to 1927 K (1538-1654 °C) and predicted results of dephosphorisation and desulphurisation abilities or potentials. Not only the proposed coupling relationships between dephosphorisation and desulphurisation potentials but also the correlated coupling relationships between dephosphorisation and desulphurisation abilities for the slags in reducing and oxidising zones have been verified to be indeed independent of slag oxidisation ability.