Effect of P 2 O 5 addition on enrichment behaviour of phosphorus in CaO–SiO 2 –FeO–P 2 O 5 slag

Abstract

The CaO–SiO₂–FeO–P₂O₅ slag was measured by Raman spectra, and the changes in the structure and behaviour of phosphorus were analysed under different slag components. The results proved that phosphorus exists in two enrichment behaviours in the slag, which can be judged according to the mole fractions of Q¹(Si), Q²(Si), and Q³(Si). When the content of P₂O₅ increases from 4.5% to 8.5%, the Q⁰(P) intensity changes most significantly. Since the Fe–O bond energy (390.4 kJ mol⁻¹) is weaker than the P–O (410 kJ mol⁻¹) bond energy, the silicon-oxygen network structure will show a behaviour change of depolymerization first and then polymerization. XRD analysis shows that with the increase of P₂O₅ content, different calcium silicate phases are added and decreased in the slag, and the content of a small amount of calcium ferrite phase changes, bonds or separates from each other, which is consistent with the change law of Raman analysis.