Abstract:
The effect of CaCO
3, Na
2CO
3, and CaF
2 on the reduction roasting and magnetic separation of high-phosphorus iron ore containing phosphorus in the form of Fe
3PO
7 and apatite was investigated. The results revealed that Na
2CO
3 had the most significant effect on iron recovery and dephosphorization, followed by CaCO
3, the effect of CaF
2 was negligible. The mechanisms of CaCO
3, Na
2CO
3, and CaF
2 were investigated using X-ray diffraction (XRD), scanning electron microscopy and energy dispersive spectrometry (SEM–EDS). Without additives, Fe
3PO
7 was reduced to elemental phosphorus and formed an iron–phosphorus alloy with metallic iron. The addition of CaCO
3 reacted with Fe
3PO
7 to generate an enormous amount of Ca
3(PO
4)
2 and promoted the reduction of iron oxides. However, the growth of iron particles was inhibited. With the addition of Na
2CO
3, the phosphorus in Fe
3PO
7 migrated to nepheline and Na
2CO
3 improved the reduction of iron oxides and growth of iron particles. Therefore, the recovery of iron and the separation of iron and phosphorus were the best. In contrast, CaF
2 reacted with Fe
3PO
7 to form fine Ca
3(PO
4)
2 particles scattered around the iron particles, making the separation of iron and phosphorus difficult.