Natural Zn reserves may be exhausted in the coming decades. Electric arc furnace (EAF) dust is an essential secondary Zn resource. However, the traditional methods for separating Zn from EAF dust are plagued by high energy consumption, large carbon emissions, and severe environmental pollution, which hinder sustainable development. To address these challenges, a novel technology using molten MgCl 2 has been proposed. Under an air atmosphere at 1000°C, the chlorination percentage of Zn can exceed 97%. The ZnCl 2 content in the volatile products can reach up to 85 mass%, with minor impurities consisting mainly of PbCl 2 , KCl, and NaCl. Molten salt electrolysis experiments indicate that removing Pb 2+ and Fe 3+ ions and subsequently preparing metallic Zn is feasible. With its streamlined process, characterized by high efficiency and low energy consumption, this technology offers a clean and sustainable solution for metal recovery from EAF dust.
Yun Li,Zelong Huang,Liyuan Chai,Yunyan Wang,Xin Wang,Yong Ke,Cong Peng,Xiaobo Min
High-silica-calcium oxygen-sulfur mixed lead-zinc (HSC-PbZnOS) ore is a complex and refractory resource. This study proposed a novel and cleaner process to extract zinc and conserve sulfur and calcium in CaS form from HSC-PbZnOS concentrate. After mineral composition characterization of HSC-PbZnOS concentrate, thermodynamic and experimental investigations reveal that zinc oxides can be directly reduced by carbon, ZnS first reacted with CaO above 770 ℃ to form a stable intermediate CaZnSO (CaO + ZnS → CaZnSO), which is subsequently reduced above 1126 ℃ to Zn(g) and CaS (CaZnSO + C → Zn(g) + CO + CaS). Thus sulfur was fixed as CaS and SO₂ emission was avoided. SiO₂ tended to react with CaO to form silicates, partially inhibiting sulfur-fixation. However, under reducing conditions around 1300 ℃, silicate decomposed to release CaO, allowing it to regain reactivity with ZnS. In addition, pilot tests show that adding 10 wt% limestone increased the Zn reduction rate to 98.9% and the sulfur fixation rate to 98.1%. The gaseous product was ZnO, and the residue mainly consisted of individual SiO₂ and CaS. This work provides a clean, short-process route for efficient utilization of complex HSC-PbZnOS resources with industrial potential.
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