摘要
Bastnaesite significantly accelerates hydrogen reduction of hematite. • Iron recovery increased from 82.93% to 99.96% with bastnaesite at 475°C. • Ce redox pairs and oxygen vacancies enhance hematite reduction kinetics. • Natural rare earth additives enable efficient, low-carbon iron ore processing. Hydrogen reduction of hematite followed by magnetic separation is a promising low-carbon route for iron ore beneficiation, but its relatively high reduction temperature limits practical application. Here, naturally occurring bastnaesite (RECO 3 F) was used as a low-cost promoter to enable low-temperature hydrogen reduction of hematite. Its effects were compared with those of rare-earth oxyfluoride (REOF), the main decomposition product of bastnaesite, and synthetic CeO 2 . Thermodynamic calculations, isothermal kinetic analysis, magnetic separation experiments, and comprehensive characterizations were integrated to elucidate the reduction behavior and promotion mechanism. Bastnaesite lowered the apparent activation energy from 48.93 to 45.58 kJ·mol -1 , while the reduction process remained governed by a diffusion-controlled shrinking-core mechanism. After the addition of bastnaesite, the iron recovery increased from 82.93% to 99.96% (mass), and the total iron grade improved from 69.52% to 70.08% (mass) at temperature of 475°C. The enhanced reduction was attributed to the combined effects of Ce(III)/Ce(IV) redox cycling, oxygen vacancy formation, improved gas diffusion, and in situ CO generation via the water-gas shift reaction using CO 2 released during bastnaesite decomposition. Bastnaesite also suppressed the over-reduction of magnetite to weakly magnetic wüstite above 550°C, thereby preserving magnetic separation efficiency. These findings demonstrate that natural bastnaesite can serve as an effective promoter for energy-efficient hydrogen-based iron recovery. Download: Download high-res image (190KB) Download: Download full-size image
危险品化学品经营许可证（带存储）