Enrichment of iron from bauxite waste in chemical looping combustion

This work reports a method and findings related to the enrichment of iron from bauxite waste (red mud) using chemical looping combustion (CLC). According to the results from X-ray Diffraction, X-ray Fluorescence, and scanning electron microscope–energy-dispersive X-ray spectroscopy, uniformly distributed iron in the red mud particles migrated outward to the surface during the 148 redox cycles in a bubbling fluidized bed reactor, in which the size-reduced iron-oxide particles due to attrition are concentrated in filters. The concentrations of iron oxide in raw particles and attrition fines are 43 wt.% and 83–87 wt.%, respectively. Since the attrition in CLC is inevitable, this recycled iron oxide can be a valuable by-product to compensate for the cost of CLC, whereas the bed materials continue to participate in the CLC process. Moreover, the abundant bauxite waste can be processed in an eco-friendly manner for integrated power generation, carbon capture, and iron recovery by the proposed strategy in this work.