Reduction behavior of zinc ferrite in EAF-dust recycling with CO gas as a reducing agent

• Recovering zinc and iron from EAF-dust using CO gas as a reducing agent is studied.
• Zinc ferrite is completely reduced to metallic zinc and iron at 950 °C.
• The mass balance indicates a high zinc recovery ratio of over 99%.
• The procedure is slightly influenced by alkali chloride or lead compounds.
• The mass balance shows that this process is characterized by zero waste.

EAF-dust containing metal oxides can be regarded as an important source for zinc and iron. In this study, the reduction behavior of zinc ferrite with CO gas as a reducing agent under different temperatures was investigated to develop a new process for the recovery of zinc and iron from EAF-dust. The results of the phase studies with synthetic franklinite show that zinc substituted wustite, and spinel with low zinc content formed at lower temperatures from 450 to 850 °C due to incomplete zinc–iron-separation. Zinc ferrite was completely reduced to metallic zinc and iron at 950 °C. After evaporation and condensation, metallic zinc was collected in the form of zinc powder while iron, the reduction residue, was obtained in the form of direct reduced iron (DRI). The mass balance indicates a high zinc recovery ratio of over 99%. The new treatment process by thermal reduction with CO gas as a reducing agent achieved higher recovery and metallization grade of both zinc and iron from EAF-dust at lower temperatures than other commercial processes. The metallic products can be used directly as semi-products or as raw materials for refinery.