Dephosphorisation behaviour of BOF crude steel using CaO-based flux

ABSTRACT

A dephosphorisation technology using CaO-based flux during the tapping process of basic oxygen furnace (BOF) converter was developed by metallurgists. In order to understand the dephosphorisation mechanism during this process, laboratory experiments were carried out using industrial BOF crude steel and some CaO-based fluxes. It was found that the dephosphorisation behaviour of CaO in BOF crude steel differs from that of the dephosphorisation processes of hot metal. Owing to the lack of liquid phase, the efficiency of dephosphorisation using pure CaO is relatively low. The formation of 2CaO·SiO₂ phase is also crucial, but the low Si content in BOF crude steel restricts the formation of 2CaO·SiO₂–3CaO·P₂O₅ (C₂S–C₃P), thus affects the dephosphorisation efficiency. Kinetically, suitable addition of SiO₂ and FeO_x can accelerate the dissolution of the flux; and thermodynamically, the addition of SiO₂ is helpful for the formation of C₂S–C₃P, resulting in a better dephosphorisation efficiency.

KEYWORDS:

• Dephosphorisation
• BOF crude steel
• CaO
• dicalcium silicate

Acknowledgements

Ansteel Group Co. Ltd. is acknowledged for the supply of the BOF crude steel used in the present study.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Natural Science Foundation of China under grant numbers 52074073 and U20A20272.