Effects of Interfacial Oxygen Potential and Slag Phase Changing during Slag Formation Process on Dephosphorization Behavior

Abstract

The effects of interfacial oxygen potential and slag phase changing during slag formation process on dephosphorization behavior when the decarburization slag is recycled are investigated by XRD and SEM. The research results show that the remove of phosphorus is mainly accomplished in the first 5 minutes for the condition 1(initial lump-sum addition of lime and Fe₂O₃), however the remove of phosphorus is mainly done from 5 to 10 minutes for the conditions 2(divided addition of lime and Fe₂O₃) and 3(initial lump-sum addition of lime and divided addition of Fe₂O₃). The dephosphorization rate of the condition 1 is about 78.9%, which is significantly higher than those of the conditions 2 and 3. The phase of decarburization slag is mainly made up of 2CaO·SiO₂-3CaO·P₂O₅ and Ca₃Fe₂O₅, the phosphorus mainly enriches in 2CaO·SiO₂-3CaO·P₂O_5. After the recycling of decarburization slag, the slag phase with reactions under different conditions is basically the same, which is made up of FeO, 2CaO·SiO₂, 2CaO·SiO₂-3CaO·P₂O₅ and Ca₃Fe₂O₅. However, the contents of 2CaO·SiO₂ and 2CaO·SiO₂-3CaO·P₂O₅ change seriously. The reason for the difference of dephosphorization behavior is that the interfacial oxygen potential and the slag phase changing during slag formation process are significantly different between different conditions.