Migration behavior of iron and phosphorus during gas-based reduction for high-phosphorus iron ore

With the depletion of high-grade iron ore, it is necessary to develop low -quality high -phosphorus iron ore through economical and sustainable solutions. In this study, we presented simultaneous enrichment of iron (Fe) and phosphorus (P) to recover P from high -phosphorus iron ore and clarified the migration of P from the original apatite to reduced iron during the direct reduction process. To capture the migration route, gas -based reduction at a relatively slow rate was conducted on two typical iron ores samples (low-grade and high-grade) at different temperatures and times. Results indicate that there are concentration gradients for P and Fe of reaction products in the low-grade iron ore at 1400 degrees C. The P content continuously increased in the sequence from metallic iron (Fe), wustite (FeO), and fayalite (Fe 2 SiO 4 ), to apatite (Ca 3 (PO 4 ) 3 F). Conversely, the content of Fe gradually decreased. During this process, P dissolved from apatite entered and formed P -bearing fayalite. For the highgrade iron ore, P -bearing fayalite with a metastable structure disappeared as the reduction progressed, and P was released and then reduced to a gaseous state, finally absorbed by metallic iron. Furthermore, when metallic iron was not formed in the initial 60 min at 1300 degrees C, the P migrated from the apatite to the fayalite and gas phase. As the reduction time increased from 60 min to 240 min, the formed metallic iron provided a site for gasified P, which inhibited the volatilization of P and contributed to Fe and P enrichment.