The effect of B2O3 on dephosphorization of molten steel by FeOx-CaO-MgOsatd.-SiO2 slags at 1873 K

Reducing the exhaust amount of steelmaking slag is strongly required because of the view point of environmental conscious. CaO is often used for steelmaking slag but its high melting point prevents from reuse of slag as resources because free-CaO exists in the melt. Therefore highly dissolution of CaO is the key for reducing steelmaking slag. It was reported that B2O3 accelerates CaO dissolution into slag, however, few study about B2O3 containing slag has been conducted. The present work measured phosphorus partition ratio between liquid iron and MgO saturated FeOx-CaO-MgOsatd.-SiO2-B2O3 melts or MgO and CaO doubly saturated FeOx-CaOsatd.-MgOsatd.-SiO2-B2O3 melts at 1873 K. If SiO2 was replaced by B2O3, phosphorus partition ratio does not change. The maximum phosphate capacity is 10(19.06) for MgO and CaO doubly saturated FeOx-CaOsatd.-MgOsatd.-B2O3 system. The activity coefficient of PO2.5 is calculated as a function of CaO content and following equation is derived for present experimental conditions. log gamma(PO2.5) = -6.2 - 0.046 X (mass%CaO)