Study on the Mechanism of CaO–SiO₂–FeO–P₂O₅ Dephosphorization Slag Under Different FeO Contents and Basicity

To further elucidate the mechanism of high‐efficiency deep dephosphorization using the duplex method, the morphology, mineral phase structure, and phosphorus aggregation behavior of the CaO–SiO 2 –FeO–P 2 O 5 slag system with varying FeO content and basicity are analyzed using fourier transform infrared spectrometer, X‐ray diffractometer (XRD), and scanning electron microscope‐energy dispersive spectrometer. XRD analysis reveals that as the FeO content increases, FeO combines with SiO 2 and CaO to form the Ca 3 Fe 2 (SiO 4 ) 3 phase. Observation of the dephosphorization slag's morphology reveals that, at a basicity of 1.8, an increase in FeO content from 10% to 30% leads to the aggregation and growth of the phosphorus‐rich phase, accompanied by an increase in phosphorus content. When the basicity of slag is 2.8 and the content of FeO is 35%, phosphorus is distributed in matrix phase and iron‐rich phase, but the content of phosphorus in all phases is low. The increase in both FeO content and basicity disrupts the polymerization degree of the structure, leading to an increase in the content of low‐polymerization Q n (Si) species and thereby reducing phosphorus accumulation on the silicon–oxygen network. This study provides a theoretical basis and practical guidance for iron and steel enterprises aiming to produce low‐phosphorus and ultralow‐phosphorus steel through the double‐dephosphorization process.