Effect of CaF2 on Phosphorus Refining from Molten Steel by Electric Arc Furnace Slag using Direct Reduced Iron (DRI) as a Raw Material

The effect of CaF2 addition on dephosphorization reaction between molten steel and electric arc furnace (EAF) slag using direct reduced iron (DRI) at 1823 K (1550 °C) was investigated. Basicity, the thermodynamic parameter affecting the removal capacity of phosphorus (i.e., phosphate capacity), decreased using DRI due to an increased SiO2 concentration in the slag. To minimize slag volume and maximize dephosphorization efficiency, the CaF2 was added to the slag. As CaF2 content increased (0 to 10 mass pct), dephosphorization efficiency also increased. Thermodynamic analysis in conjunction with slag structural studies using Raman spectroscopy were conducted to explain the complicated phenomena. The results exhibited that even 5 to 6 mass pct CaF2 can improve the dephosphorization efficiency when DRI is used as raw material in an EAF process.