低氧分压条件下CaO-SiO_2-P_2O_5(10%)-FeO体系热力学性质的研究

Research on the thermodynamic properties of CaO-SiO_2-P_2O_5( 10%)-FeO oxide system under low oxygen partial pressure

以促进2CaO·SiO_2-3CaO·P_2O_5固溶体生成的非均相脱磷工艺被视为未来实现转炉少渣冶炼的重要手段,但目前相关渣系热力学性质的研究较少,不能为合理解释非均相渣脱磷的机理提供理论依据.为此,本文利用FactSage热力学软件绘制了低氧分压(1mPa)条件下CaO-SiO_2-P_2O_5(10%)-FeO体系及其子体系的热力学相图,分析了不同温度下相平衡关系及液相线的变化规律.研究结果表明:升高温度可使体系中液相区及Ca_3(PO_4)_2初晶区的范围扩大,但会导致α'-Ca_2SiO_4的初晶区缩小以及Ca_2Fe_2O_5等物相的消失;降低氧分压可使体系的液相区缩小,并向高FeO的方向收缩;CaO-SiO_2-P_2O_5(10%)-FeO体系中存在较大的α'-Ca_2SiO_4与Ca_3(PO_4)_2共存区,尤其是α'-Ca_2SiO_4,Ca_3(PO_4)_2与Ca_2Fe_2O_5的三相共存区可极大地促进2CaO·SiO_2-3CaO·P_2O_5固溶体的生成.

The multi phase flux dephosphorization technology is an important method for the converter smelting.However the thermodynamic properties of related slag system are less seen in the publications. Therefore,CaO- SiO_2- P_2O_5（ 10%）- FeO slag systems phase diagrams at a lowoxygen partial pressure（ 1 mPa） were plotted through the thermodynamic software package Fact Sage. Effects of temperature on equilibrium phase relations and the liquides were analyzed. The results showed that temperature increase can enlarge the liquid region and the primary phase field of Ca3（ PO_4）_2,so cause reduction of the α＇- Ca_2SiO_4 field and disappearance of Ca_2Fe_2O_5. The liquid region is reduced and shifted toward the high- Fe area the oxygen partial pressure decrease. CaO- SiO_2- P_2O_5（ 10%）- FeO slag systems contain a large coexistence zone of α＇- Ca_2SiO_4and Ca_3（ PO_4）_2,especially the three phase regions ofα＇- Ca_2SiO_2,Ca_3（ PO_4）_2and Ca_2Fe_2O_5 can greatly promote formation of 2CaO ·SiO_2- 3CaO ·P_2O_5solid solution.