A recycling process of iron from red mud by magnetic separation is proposed, in which iron oxide (Fe2O3) in red mud transforms to magnetite (Fe3O4) by anaerobic co-roasting with pyrite (FeS2).TG-DTA and XRD results showed that hematite was reduced to magnetite by the thermo-decomposed compounds (iron monosulfide, pyrrhotite and element sulfur) of pyrite. The mole ratio of pyrite to hematite and the roasting temperature effected the transformation. In the simulated experiment, 30 g red mud containing 9.24% of iron (13.2% in Fe2O3) mixed with 0.74g pyrite were roasted at 600 degrees C under N-2 atmosphere for 30 min. 4.5 g magnetic material (with Fe content of 36.9%) was magnetically separated, and the remaining solid only containing 0.61% of Fe (0.87% in Fe2O3), being able to meet the stipulated standard of 2% for refractory material manufacture. (C) 2014 Elsevier B.V. All rights reserved.