Pulverized Sponge Iron, a Zero-Carbon and Clean Substitute for Fossil Coal in Energy Applications

The direct combustion of recyclable metals has the potential to become a zero-carbon energy production alternative, much needed to alleviate the effects of global climate change caused by the increased emissions of the greenhouse gas CO 2 . In this work, we show that the emission of CO 2 is insignificant during the combustion of pulverized sponge iron compared to that of pulverized coal combustion. The emissions of the other harmful pollutants NO x and SO 2 were 25 and over 30 times lower, respectively, than in the case of pulverized coal combustion. Furthermore, 96 wt % of the solid combustion products consisted of micrometer-sized, solid or hollow hematite (α-Fe 2 O 3 ) spheres. The remaining 4 wt % of products was maghemite (γ-Fe 2 O 3 ) nanoparticles. According to thermodynamic calculations, this product composition implies near-complete combustion, with a conversion above 98%. The results presented in this work strongly suggest that sponge iron is a clean energy carrier and may become a substitute to pulverized coal as a fuel in existing or newly designed industrial systems.