Laser-assisted reduction of iron ore using aluminum powder

Abstract

This study reports on the laser-assisted reduction of iron ore waste using Al powder as a reducing agent. Due to climate change and the global warming situation, it has become of paramount importance to search for and/or develop green and sustainable processes for iron and steel production. In this regard, a new method for iron ore utilization is proposed in this work, investigating the possibility of iron ore waste reduction via metallothermic reaction with Al powder. Laser processing of iron ore fines was performed, focusing on the Fe2O3–Al interaction behavior and extent of the iron ore reduction. The reaction between the materials proceeded in a rather intense uncontrolled manner, which led to the formation of Fe-rich domains and alumina as two separate phases. In addition, a combination of Al2O3 and Fe2O3 melts, as well as transitional areas such as intermetallics, was observed, suggesting the occurrence of incomplete reduction reaction in isolated regions. The reduced iron droplets were prone to acquire a sphere-like shape and concentrated mainly near the surface of the Al2O3 melt or at the interface with the iron oxide. Scanning electron microscopy, energy-dispersive x-ray spectroscopy, and wavelength-dispersive x-ray spectroscopy analyses were employed to analyze the chemical composition, microstructure, and morphological appearances of the reaction products. High-speed imaging was used to study the process phenomena and observe differences in the movement behavior of the particles. Furthermore, the measurements acquired from x-ray computed microtomography revealed that approximately 2.4% of iron was reduced during the laser processing of Fe2O3–Al powder bed, most likely due to an insufficient reaction time or inappropriate equivalence ratio of the two components.