Influence of Sodium Salts on Reduction Roasting of High-Phosphorus Oolitic Iron Ore

ABSTRACT

The reduction roasting followed by magnetic separation process is considered to be a suitable method to treat the high-phosphorus oolitic iron ore. Currently, the dephosphorization mechanism of additives such as CaCO₃, Ca(OH)₂, Na₂SO₄, and Na₂CO₃ on the reduction roasting of the iron ore in which phosphorus occurs in apatite have been thoroughly studied. The effect of sodium salts (Na₂CO₃, NaCl and Na₂SO₄) on reduction roasting and magnetic separation of high-phosphorus oolitic iron ore containing phosphorus in iron oxides was investigated, and the mechanisms of sodium salts were expounded using XRD and SEM-EDS. The results show that the dephosphorization ability of sodium salts was in the order of Na₂SO₄> Na₂CO₃> NaCl>no sodium salts. Na₂CO₃ and Na₂SO₄ transferred Fe₃PO₇ from the iron oxides to nepheline, which upgraded the separation of iron and phosphorus. However, NaCl did not inhibit the reduction of phosphorus in the iron minerals. In addition, Na₂CO₃ strengthened the reduction of iron oxides. However, a small amount of wustite failed to be reduced to metallic iron with the addition of NaCl, and troilite and wustite formed hindered the reduction of iron minerals after adding Na₂SO₄.

KEYWORDS:

• High-phosphorus oolitic iron ore
• sodium salts
• reduction roasting
• dephosphorization

Acknowledgments

The authors wish to express their thanks to the National Natural Science Foundation of China (Grant No. 51874017) for the financial support for this research.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the The National Natural Science Foundation of China [51874017].