Effect of P₂O₅ on the viscous flow and crystallisation behaviour of slag in the double slag converter steelmaking process

In the current study, the effect of P 2 O 5 on the viscous flow and crystallisation behaviour of slag in the double slag converter steelmaking process was investigated in laboratory. The results indicated that with the increase of P 2 O 5 content, the softening temperature, hemispherical temperature and flowing temperature of steelmaking slag showed a decreasing trend, however, the viscosity increased. The FactSage thermodynamic software was used to predict the types and contents of crystallisation phases in the crystallisation process of steelmaking slag. It showed that with the increase of P 2 O 5 content, the precipitation content of Ca 5 P 2 SiO 12 increased, while the precipitation content of melilite decreased. The composition and microstructure of crystallisation phases were analysed using X-ray diffraction and scanning electron microscopy. The phase composition did not change with the increase of P 2 O 5 content, but the diffraction peak intensity of each crystallisation phase was different. Besides, the precipitation of phosphorus-enriched phase was enhanced with the increase of P 2 O 5 content.