Effect of CaCl2 Addition on Phosphorus Distribution in CaO–SiO2–FeOx–P2O5 Converter Slags

Laboratory experiments are carried out to investigate the effect of CaCl 2 addition on the phosphorus distribution in CaO–SiO 2 –FeO x –P 2 O 5 converter slags. Some slags with different slag basicity [ R = w (CaO)/ w (SiO 2 )] and P 2 O 5 contents are melted at steelmaking temperature and further analyzed by scanning electron microscope (SEM). It is found that the nature of liquid is generally seen in the slags with low basicity ( R = 1.0). With the increase in slag basicity and CaCl 2 content, the proportion of 2CaO·SiO 2 –3CaO·P 2 O 5 (C 2 S–C 3 P) solid solution in the slags climbs in general, but the P content in C 2 S–C 3 P is degraded. A new P‐rich phase Ca 5 Cl(PO 4 ) 3 (C 5 P 3 Cl) with a fixed P content can be observed in the high‐basicity slags ( R ≥ 1.5), when the contents of CaCl 2 and P 2 O 5 are sufficiently high. Higher contents of both CaCl 2 and P 2 O 5 can further promote the proportion of C 5 P 3 Cl. The addition of CaCl 2 is unfavorable for the recycling of P from CaCl 2 ‐added slags, but its effect is still limited in case of a small amount.