Equilibrium of CaO-SiO2-FeO-P2O5 multi phase flux at 1673K with low oxygen partial pressure for dephosphorization
Dephosphorization process by using multi phase flux could significantly decrease the consumption of CaO and prevent environmental harmful fluorite addition. However, the equilibrium phase relationship remains unclear, which is important for understanding the reaction mechanism of solid phase in the multi phase flux. Therefore, it is necessary to clarify the phase diagrams for better utilization of multi phase flux on dephosphorization process. In this study, the CaO-SiO2-FeO-P2O5 slag system is chosen since it represents the main slag composition during dephosphorization reaction, and the phase relationship of this slag system has been measured by using chemical equilibration technique. The results show that the condensed solid solution is mainly composed of 2CaO·SiO2 and 3CaO·P2O5, but sometimes contains certain amount of 3CaO·SiO2 or CaO·SiO2 according to the CaO/SiO2 ratio in molten slag. The liquidus equilibrated with P2O5-containing solid solution shrinks to the FeO apex with the oxygen partial pressure of 10-10 atm comparing with the well-known isothermal phase diagram for the CaO-SiO2-FeO system equilibrated with metallic iron, and it shifts further towards the FeO apex with higher oxygen partial pressure of 10-8 atm. On the other hand, a stable CaO-FeO phase appears despite of oxygen partial pressures, which has been observed previously when solid CaO reacted with molten slag in previous works. The phosphorus partition ratio between solid solution and liquid slag obtained in this research agrees well with previous works, which is that the phosphorus partition ratio increases linearly with T.Fe content but decreases with CaO content in liquid phase.
Steelmaking Multi phase flux Phase relationship Equilibrium Dephosphorization
Xu GAO Hiroyuki MATSUURA Fumitaka TSUKIHASHI
Graduate School of Frontier Sciences, The University of Tokyo, 2778561, Japan
国际会议
Ninth International Conference on Molten Slags,Fluxes and Salts(第九届国际熔渣、溶剂与熔盐学术会议 MOLTEN12)
北京
英文
1-8
2012-05-27（万方平台首次上网日期，不代表论文的发表时间）