On the Pore Formation During the Combustion of Direct Reduced Iron Powders

Iron fuel is a promising high‐energy density energy carrier. Using recycled iron‐rich sources, such as Direct Reduced Iron (DRI) ores, is of strong economic interest considering the added costs from purifying iron, but the influence of oxidized additions (Si, Al, Mn oxides) on the combustion process has hardly been investigated. In this study, the combustion products of DRI powder is compared to that of pure Fe in an open propane flame. The microstructure and chemical changes are characterized at different scales using a combination of SEM‐EDS and STEM‐EDS. Pore formation in combusted DRI and pure Fe powders is compared using X‐ray computed tomography (CT), BET surface area and gas pycnometer measurements, together with laser diffraction and image analysis granulometry. The role of oxygen gas release on the pore formation and the major modifications brought by the presence of Si are unveiled for the first time by a combination of experimental characterization and thermodynamic simulations. Crucially, our findings show that DRI is a viable source of Fe fuel. This paves the way for more sustainable and economically competitive high‐energy‐density carriers.