• Microwave fluidization roasting significantly increases the specific surface area of limonite, enhancing CO contact and accelerating phase transformation from FeO(OH) to α-Fe2O3 and then to Fe3O4.
• The water in limonite and newly formed magnetite exhibit strong microwave absorption, activating the reduction roasting process.
• The process yields an iron concentrate with Fe grade of 59.26wt% and recovery of 90.07wt% after magnetic separation.
• Kinetic analysis reveals a diffusion-controlled mechanism (G(α) = α2) with activation energy of 20.34 kJ/mol, providing a basis for process optimization.