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.