Abstract

Steelmaking dusts generated from Basic Oxygen Furnace (BOF) and Blast Furnace (BF) processes are industrial residues with high iron content (54-70%), but their direct reuse is limited by impurities such as Ca, Mg, Si, and Al. This study proposes a sustainable valorisation strategy combining selective acetic acid leaching with controlled thermochemical reduction. Initial morphological characterization revealed marked differences: BF powders exhibited smooth spherical particles (208.7 +/- 90.0 mu m), while BOF powders showed irregular, highly porous structures (31.0 +/- 19.0 mu m). Leaching with acetic acid (33-50% v/v) under controlled conditions (30-70 degrees C, 2-5 h) achieved up to 98% removal of Ca and Mg at optimal parameters (70 degrees C, 33% for 2 h). In BOF powders, residual Ca and Mg contents were significantly reduced, demonstrating acetic acid's high selectivity. XRD analyses revealed significant phase transformations: in BF powders, CaCO3 was eliminated with notable hematite reduction and magnetite enrichment, while BOF powders achieved high magnetite content. These results demonstrate that acetic acid selectively removes alkaline impurities while enriching reactive ferric phases, thereby enhancing subsequent reduction efficiency. Thermochemical reduction enabled extensive conversion to metallic iron in BOF powders, yielding high-purity material suitable for powder metallurgy applications. Conversely, BF powders showed incomplete reduction with residual oxides and silicates, attributed to higher Si and Al content in resistant phases. These findings provide a viable and environmentally sustainable separation route for iron recovery from steelmaking waste, advancing circular economic principles in the steel industry while demonstrating superior performance for BOF residues.