In order to recycle the phosphorus in P-bearing converter slag and make it used as slag phosphate fertilizer, the effect of Na
2O in P-bearing steelmaking slag on phosphorus existence form, P
2O
5 solubility and magnetic separation behavior was researched systematically. The results show that the melting point of slag decreases obviously with the increasing of Na
2O content in slag, and high phosphorus solid solution (Ca
2SiO
4–Ca
3(PO
4)
2 and Na
2Ca
4(PO
4)
2SiO
4) are generated by the continuous reaction of 6Ca
2SiO
4–Ca
3(PO
4)
2 (for short 6C
2S–C
3P) solid solution precipitated in the slag with Na
2O under the condition of 1623 K. The early precipitated 6C
2S–C
3P solid solution is reduced with the increasing content of Na
2O even disappeared. If the addition of Na
2O is increased or excess in the slag, the high phosphorus solid solution (Na
2Ca
4(PO
4)
2SiO
4) that generated by the above mentioned reaction will continue to react with Na
2O to produce Na
3PO
4, then the phosphorus content in the phosphorus-rich phase is heightened. Na
2Ca
4(PO
4)
2SiO
4 and Na
3PO
4 have almost same good citric acid solubility with 6C
2S–C
3P solid solution. Therefore, adding appropriate Na
2O content into slag can improve the slag P
2O
5 solubility, but the effect of different amounts of Na
2O on the P
2O
5 solubility has little difference. Meanwhile, Added Na
2O into slag can improve the metallization of slag and magnetism of iron-rich phase, make the magnetic substances content increased and separation of phosphorus and iron is incomplete, so it is adverse to phosphorus resources recovery from P-bearing slag by magnetic separation method. In order to recycle the phosphorus in P-bearing converter slag, adding appropriate Na
2O content (<6%) into slag can be used as a flux to instead of fluorite for slag forming in steelmaking process.
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