Mineralogical characterization and flotation properties of rare earths in refractory iron tailings subjected to hydrogen-based mineral phase transformation

• HMPT effectively separates iron and enriches rare earths from Bayan Obo refractory ores, with tailings containing 9.15wt% REO, 5.31wt% monazite, and 23.52wt% fluorite. • Closed-circuit flotation achieved a REO grade of 60.27wt% with 73% recovery, demonstrating the feasibility of rare-earth recovery from HMPT-treated tailings. • Monazite remains stable during HMPT, while bastnaesite transforms into Ce7O12 and CeF3, increasing collector consumption but not significantly affecting flotation performance. • The integration of HMPT, magnetic separation, and flotation offers a promising strategy for comprehensive recovery of iron, rare earths, and fluorite from Bayan Obo ores.