Evaluation of Brazilian Iron-Based Ore and Industrial Waste as Low-Cost Oxygen Carriers for Chemical Looping Process

Given the crucial role of oxygen carriers in advancing chemical looping (CL) technology, the innovation of this study lies in the evaluation of inexpensive and readily available materials, specifically iron ores (Carajas iron ore, CRJ) and residues from the steel industry in Brazil [mill scale residual (MSR), iron spill residue (ISR)], as yet unexplored oxygen carriers in this process. These materials were analyzed for their chemical composition, crystalline structure, and redox properties during reactivity testing on a thermogravimetric analyzer. Among all the materials, CRJ, MSR, and ISR exhibited the highest conversions with H2 fuel gas. Notably, CRJ displayed a higher oxygen transport capacity (Roc = 3.92) and a higher Rate Index with CH4 (RICH4 = 13,94%/min and RIair = 12,01%/min). Consequently, this material was selected for testing in the discontinuous fluidized bed reactor under CL conditions, evaluating gaseous product distribution, mass loss rates due to attrition, particle agglomeration, and carbon deposition. CRJ demonstrated excellent fuel conversion and reactivity with H2 (H2 > CO > CH4), and the conversion increased with temperature, reaching complete combustion in the initial period of reduction at 950 degrees C, achieving Xred = 0.113 and Xox = 0.155, indicating complete regeneration. There was no carbon deposition, low attrition loss, and a stable lifetime of 15,000 h. It also maintained reactivity under hydrogen gas without agglomeration or defluidization issues. The findings of this study carry substantial implications for upscaling CL processes utilizing low-cost materials with promising attributes.