Production of High-Purity Zinc Oxide from Zinc Fuming Dust via Dry Reduction and Wet Leaching Processes

Zinc oxide (ZnO) is a multifunctional material extensively used in ceramics, electronics, pigments, and pharmaceuticals. The increasing global demand for ZnO, coupled with growing environmental concerns, necessitates the development of resource-efficient and eco-friendly manufacturing methods. This study investigates a dry metallurgical approach for recovering high-purity ZnO powder from zinc ferrite-rich fume dust, a byproduct generated during the roasting of zinc sulfide concentrates. Fume dust samples obtained from industrial zinc roasters were characterized using X-ray fluorescence (XRF), X-ray diffraction (XRD), and scanning electron microscopy (SEM), which revealed a composition dominated by ZnO, ZnFe<sub>2</sub>O<sub>4</sub>, Zn<sub>2</sub>SiO<sub>4</sub>. A reductive volatilization process was conducted using a laboratory-scale rotary kiln at temperatures ranging from 1,100<sup>o</sup>C to 1,300<sup>o</sup>C, employing carbon and aluminum powders as reducing agents. The volatilized zinc was condensed and subsequently oxidized to form ZnO particulates. The process achieved zinc recovery efficiencies of up to 96% under optimized conditions, and the final ZnO purity exceeded 99.3% by weight. The produced ZnO powder exhibited particle sizes ranging from tens to hundreds of μm and was recovered in an amorphous form. The residual slag contained less than 1% Zn, and most of the Fe remained in a solid state, suggesting the possibility of reuse as an iron source in metallurgical fields. In addition, zinc could be purified and recovered as spherical zinc oxide of approximately 300 nm through a wet smelting process. Finally, nanosized zinc oxide with a purity of approximately 99.84% could be recovered. This work demonstrates that dry metallurgical processing of zinc fume dust offers a sustainable route to high-value ZnO production, minimizing wastewater generation and enabling the circular utilization of metallurgical byproducts.