Distribution and enrichment of phosphorus in solidified BOF steelmaking slag

Abstract

The distribution of P in basic oxygen furnace steelmaking slag was investigated together with the enrichment behaviours of P in slowly cooled slag samples modified by SiO₂ from high temperature remelts at 1873 K. The slag microstructures were characterised, and the results showed that only a limited fraction of P₂O₅ was dispersed in the matrix, whereas a large amount of P₂O₅ was found to form solid solutions with dicalcium silicate (2CaO.SiO₂ or C₂S) phase and/or with tricalcium silicate (3CaO.SiO₂ or C₃S) phase in original industrial slag. It was also found that when the basicity (C/S = CaO/SiO₂) of slag modified by SiO₂ was close to 3, the main phase was C₂S, and most of the P in the modified slag was precipitated from solid solution in the C₂S. The mechanism of P enrichment is also discussed.

Keywords:

• Steel slag
• P
• C₂S
• C₃S
• Enrichment

The authors would like to thank Baosteel and Masteel for supplying the BOF steel slag samples and the Anhui Provincial Natural Science Foundation (project no. 090414150) and the Natural Science Foundation of Education, Department of Anhui, China (grant nos. KJ2009A69 and KJ2008A038) for the financial support. The experimental support from the International Cooperation Project from Anhui Science and Technology Department of China (project no. 09080703019) is also acknowledged.