Effect of Al2O3 on Enrichment of Phosphorus in Hot Metal Dephosphorization Slag

The phosphorus enrichment behavior in dephosphorization slag was investigated by slag modification with Al2O3 in the present study. The mineral phase of the slag samples were measured by mineral phase microscope, SEM+EDS and XRD. The mechanism of Al2O3 modification was discussed according to Fact-Sage calculation. The results show that phosphorus was mainly existed in nC(2)S-C3P solid solution and Al2O3 modification was beneficial to the enrichment of phosphorus. The content of phosphorus in phosphorus-rich phase was increased to 5.10% and 9.15% with 8% and 11% Al2O3 addition. With the slag temperature decreases, Ca-3(PO4)(2) and Ca2SiO4 firstly precipitated and formed the nC(2)P-C3P solid solution. The addition of Al2O3 has a positive influence on the reaction of Al2O3 and nC(2)S-C3P solid solution. Al2O3 could react with the initially precipitated low phosphorus nC(2)S-C3P solid solution to produce higher phosphorus n'C2S-C3P solid solution (n' < n) and Ca2Al2SiO7. When Al2O3 content was increased from 2% to 15%, the value of InK decreased from 2.34 to 1.47.