Investigation of Mechanism of Phosphorus Enrichment in Dephosphorization Slag with Li ₂ O Addition

Phosphorus removal is critical for ensuring the quality of steel products. Previous studies have shown that Li 2 O exhibits better performance in enhancing the dephosphorization ability of slag. Therefore, it is essential to investigate the phosphorus enrichment and dephosphorization mechanism of Li 2 O‐containing slag. In this study, the phosphorus distribution and the microstructure of slag are investigated by scanning electron microscopy–energy‐dispersive X‐ray spectroscopy, thermodynamic equilibrium calculations, Raman spectroscopy, and ab initio molecular dynamics simulations. The results show that phosphorus mainly distributes in the P‐rich phase in the form of 2Ca 2 SiO 4 ·Ca 3 P 2 O 8 before adding Li 2 O into the slag, while the P‐rich phase of 2Ca 2 SiO 4 ·Ca 3 P 2 O 8 disappears and phosphorus mainly distributes in the matrix phase after introducing Li 2 O into the slag. Besides, the addition of Li 2 O significantly strengthens the PO bond by increasing the potential energy barrier of PO bond from 111.6 to 152.2 kJ mol −1 , which can effectively inhibit rephosphorization and enhance the dephosphorization capacity of slag. Furthermore, Li 2 O can depolymerize the [SiO 4 ] and [PO 4 ] network structures and increase the free oxygen ratio, thereby reducing the slag polymerization degree and improving the dephosphorization capacity of the slag.