Abstract
Global production of electric arc furnace (EAF) dust, estimated at approximately 8 million tonnes annually, is expected to increase as EAF steelmaking gains prominence in response to global decarbonization efforts. Although classified as hazardous due to its heavy-metal content, EAF dust represents a valuable secondary resource for zinc and iron recovery. This study investigates the hydrogen-based reduction of EAF dust as a more sustainable alternative to conventional carbon-based processes. Thermodynamic calculations performed using FactSage 8.0 (Equilib and Reaction modules) reveal three distinct stability and selectivity regions for iron and zinc oxides as functions of temperature and H₂/H₂O partial pressure. These domains define the thermodynamically feasible reduction pathways and provide a basis for selective zinc reduction using hydrogen. The as-received dust was characterized mineralogically by X-ray diffraction (XRD) and chemically by inductively coupled plasma-optical emission spectroscopy (ICP-OES). Isothermal reduction experiments were conducted at 1000°C using a pure hydrogen flow rate of 2 SLPM and varying reduction times, with partially reduced samples analyzed for zinc and iron contents. Near-complete reduction was achieved within 10 minutes, exhibiting a two-stage reduction profile characterized by rapid initial mass loss during the first 5 minutes, followed by a gradual plateau. Zinc removal increased with reduction time, reaching 98% after 20 minutes. These results demonstrate the viability of hydrogen-based reduction for selective zinc recovery from EAF dust and provide valuable insights into the thermodynamic feasibility and kinetic mechanisms governing the process.