The reaction behaviour of solid 2CaO·SiO2 (C2S) in steel slag is of great interest during the hot-metal dephosphorization process. In the present work, C2S samples were prepared and interfaced with steel slag to investigate the phosphorus diffusion behaviour at the interface of C2S at 1723K at the onset of the slag melting. The results showed that the phosphorus diffusion from the slag to C2S was very rapid with a significant diffusion coefficient of 4.44 × 10−9 m2·s−1. Phosphorus-enriched phases were formed continuously with increasing reaction time. As the reaction time increases, the composition of the diffusion layer becomes closer to 3CaO·P2O5 (C3P) and farther away from the C2S. The results indicate that a hot-metal dephosphorization process with much higher efficiency can be achieved by the careful selection of the interface characteristics between the C2S and steel slag.
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