Advancing the recovery of iron and rare earth elements from the solid waste at Bayan Obo

• Hydrogen-based mineral phase transformation (HMPT) at 525 °C, 12.5 min, and 30% H2 concentration yields an iron concentrate with 64.09% TFe grade and 95.33% recovery. • Flotation optimization produces a rare earth concentrate with 65–70% REO grade and 60–65% REEs recovery. • HMPT enhances magnetic properties of solid waste, enabling effective magnetic separation of iron minerals. • Hematite is reduced to magnetite and bastnaesite decomposes to REE oxides and fluorides, while monazite, fluorite, and barite remain largely unchanged.