Electric Arc Furnace Dust as an Alternative Reactive Iron Source in Pyrometallurgical Processes for Lead–Acid Battery Recycling

Pyrometallurgical recycling of lead–acid batteries is one of the main industrial routes for secondary lead recovery; however, it still faces challenges related to residual sulfur control, matte formation, slag stability, and dependence on metallic iron as a sulfiding agent and redox regulator. In this context, electric arc furnace dust (EAFD), a steelmaking residue rich in iron oxides, emerges as a potential alternative for partially replacing conventional metallic iron scrap. This study investigated the metallurgical behavior and chemical interactions of the Pb–S–O–Fe system during partial replacement of metallic iron scrap by EAFD, using previously desulfurized lead paste as the primary lead source. Bench-scale pyrometallurgical experiments were conducted in static crucibles heated in a muffle furnace under controlled conditions. Seven Fe/EAFD ratios were evaluated to assess the effect of oxidized iron on system behavior. Material and product characterization was performed using X-ray fluorescence (XRF), ICP-OES, combustion elemental analysis (LECO), X-ray diffraction (XRD), scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM-EDS), and particle size analysis. Metallic lead recovery, effective C/O ratio, phase partitioning, and slag composition were also evaluated. Results showed that iron introduced via EAFD, predominantly as Fe₂O₃, Fe₃O₄, and FeO, underwent sequential reduction under pyrometallurgical conditions, controlling the temporal availability of reactive metallic iron. Average lead recovery decreased from 97.33% (Fe100/EAFD00) to 83.55% (Fe00/EAFD100), accompanied by an increase in slag FeO content from 12.11% to 28.09% and Pb retention in slag from 1.64% to 7.64%. The effective C/O ratio decreased from 0.34 to 0.30, indicating a shift toward less reducing conditions. Under intermediate replacement conditions (Fe50/EAFD50), 95.27% Pb recovery was maintained. Statistical analysis confirmed a significant influence of the iron source on system behavior (p < 0.001). Overall, EAFD demonstrated potential as an alternative reactive iron source in pyrometallurgical lead–acid battery recycling, provided its effects on redox balance, phase stability, and metallic recovery efficiency are considered.