Study on dephosphorisation of hot metal pretreatment with Al₂O₃ to replace CaF₂ in slag

Abstract

The substitution effect of Al₂O₃ for CaF₂ on hot metal dephosphorisation has been studied at 1723 K. The initial composition of the slag was 40%CaO (mass percentage)+52%Fe₂O₃+8%CaF₂. Then, Al₂O₃ was substituted for CaF₂ up to 8%. The hot metal initial silicon was 0·61%, and the P contents were 0·063, 0·073 and 0·091%. Experimental results showed that with increasing Al₂O₃ content, the melting point of the slag slightly increased, and the oxidising power and phosphate capacity for the slag were enhanced, which led to an increase in dephosphorisation. The range of phosphorus content at the end point was between 0·009 and 0·014%, and the corresponding dephosphorisation varied from 82·5 to 89·0%. This result may be acceptable for industrial use.

Keywords:

• Hot metal pretreatment
• Dephosphorisation
• Al₂O₃
• CaF₂

Acknowledgements

The project was supported by the National Natural Science Foundation and Steel Research Combination Foundation of China (grant no. 51074203) and the Anhui Province Natural Science Foundation (grant no. 1308085ME62).