Study on Dephosphorization of CaO-Fe2O3-Al2O3 Slag System for High Phosphorus Hot Metal

Abstract

以CaO-Fe2O3-Al2O3渣系为研究对象，利用Factsage热力学软件计算渣系组成对其熔点、粘度及组元活度的影响，通过热态实验研究渣系钙氧比及渣中w(Al2O3)对高磷铁水脱磷的影响。结果表明：CaO-Fe2O3-Al2O3渣系熔化温度随渣系钙氧比的增大而升高，随w(Al2O3)的增大而降低；渣系粘度随渣系钙氧比增大而升高；渣系中CaO组元活度随着w(Al2O3)增大而降低，随钙氧比增大先大幅度升高后略有降低；渣系中Fe2O3组元活度随钙氧比增大先大幅度降低后略有降低，随w(Al2O3)增大略有波动。渣系的脱磷能力随着钙氧比的逐渐增大先略有增大后快速降低；钙氧比为0.45，w(Al2O3) = 1%~5%时，渣系脱磷率维持在90%以上。C2S-C3P固溶体相是熔渣中磷的主要富集相，C3P以扩散和析出的形式与熔渣中的2CaO·SiO2结合生成C2S-C3P固溶体。 Taking CaO-Fe2O3-Al2O3 slag system as the research object, the effect of slag system composition on its melting point, viscosity and component activity was calculated by Factsage thermodynamic software, and the effect of Ca/O ratio of slag system and w(Al2O3) in slag on dephosphorization of high phosphorus hot metal was studied by hot state experiment. The results show that the melting temperature of CaO-Fe2O3-Al2O3 slag system increases with the increase of Ca/O ratio, and decreases with the increase of w(Al2O3); the viscosity of slag system increases with the in-crease of Ca/O ratio of slag system; the activity of CaO component in slag system decreases with the increase of w(Al2O3), and increases first and then decreases slightly with the increase of Ca/O ratio; the activity of Fe2O3 component in slag system decreases first and then tends to de-crease slightly with the increase of Ca/O ratio. It is relatively stable and fluctuates with the in-crease of w(Al2O3). The dephosphorization ability of slag system increases slightly at first and then decreases rapidly with the increase of Ca/O ratio. When Ca/O ratio is 0.45 and w(Al2O3) = 1% - 5%, the dephosphorization rate of slag system is maintained above 90%. C2S-C3P solid solution phase is the main enrichment phase of phosphorus in the slag. C3P combines with 2CaO·SiO2 in the slag in the form of diffusion and precipitation to form C2S-C3P solid solution.