RESOURCES CONSERVATION AND RECYCLING
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2024
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IF 11.2
Jingdong Huang,Xiao Yang
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.
研究领域:
冶金工程
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Central South University
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2021
·Vol. 28
·期 9
·2701-2710
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IF 1.716
Zhang Du-chao,Liu Ruo-lin,Wang Hao,Liu Wei-feng,Yang Tian-zu,Chen Lin
To recover zinc from electric arc furnace (EAF) dust, a process of primary normal pressure leaching and secondary alkaline pressure leaching is proposed. First, under the alkaline pressure leaching system, the experiment of pure zinc ferrite being reduced by iron powder was carried out. Under the optimal reduction conditions (i.e., temperature of 260 °C, NaOH concentration of 6 mol/L, liquid-to-solid ratio of 50 mL/g, and a 5-fold excess of iron powder), 89% of zinc was extracted. The iron in the reduced residue exists as a magnetite phase. Subsequently, the normal pressure leaching experiment was carried out with EAF dust as raw material, and 66% zinc was leached. The main phase of zinc in normal leaching residue was determined to be zinc ferrite. Then, the normal leaching residue was reduced by iron powder under the alkaline pressure leaching system, and 66.5% of zinc was extracted. After the two-stage leaching process, the leaching rate of zinc in EAF dust can achieve 88.7%. The alkaline pressure leaching solution can be returned as the normal pressure leaching solution, and the magnetite in the alkaline pressure leaching residue can be recovered by magnetic separation.
研究领域:
冶金工程
·
环境工程
✓ 已验证
DOI
高影响因子
Journal of Sustainable Metallurgy
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2023
·Vol. 9
·期 3
·1253-1266
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IF 2.4
Huang Jingdong,Li Guangqiang,Yang Xiao
Natural Zn reserves might be exhausted in the following decades. Electric arc furnace (EAF) dust is an essential secondary Zn resource. The recovery of Zn from EAF dust is a critical factor in the sustainable development of the Zn industry and steelmaking industry. Efficient destruction of the ZnFe 2 O 4 crystal structure and separation of Zn and Fe are the key issues to recycle EAF dust. Molten metal chlorides are believed to be effective in breaking the structure of ZnFe 2 O 4 . This work clarifies the distinct reaction behavior between ZnFe 2 O 4 and MgCl 2 or CaCl 2 . Experiments show that although MgCl 2 is a more powerful chlorinating agent, the capability of separating Zn and Fe is not as good as that of CaCl 2 . Fast and selective chlorination of Zn from ZnFe 2 O 4 happens by reacting ZnFe 2 O 4 and MgCl 2 –CaCl 2 mixture. CaCl 2 facilitates the formation of stable Fe-bearing phases, such as MgFe 2 O 4 and Ca 2 Fe 2 O 5 , thereby inhibiting the chlorination of Fe. Moreover, it becomes more effective in promoting the selectivity of chlorinating Zn by increasing temperature after adding CaCl 2 in MgCl 2 . When ZnFe 2 O 4 is subjected to chlorination using a MgCl 2 –CaCl 2 mixture (MgCl 2 –CaCl 2 –ZnFe 2 O 4 molar ratio = 1.5:1.5:1) at 950 °C for 120 min, the process results in a chlorination percentage of over 90% for Zn, with Fe chlorination percentage lower than 5%. These results demonstrate the prospect of efficient separation of Zn from ZnFe 2 O 4 by reaction with molten MgCl 2 –CaCl 2 mixture. Graphical Abstract
研究领域:
冶金工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Cleaner Production
·
2019
·
IF 6.395
Duchao Zhang,Hongbin Ling,Tianzu Yang,Weifeng Liu,Lin Chen
Electric arc furnace (EAF) dust is a hazardous waste material containing valuable elements, such as zinc (Zn) and iron (Fe), as well as other environmentally harmful elements. In the conventional process, the existence of zinc ferrite (ZnFe 2 O 4 ) in EAF dust results in a low recovery ratio of zinc and can induce high energy consumption or difficulties utilizing iron resources. In this article, a hydrothermal reduction method in a NaOH system is proposed to recover Zn selectively from EAF dust. First, when pure ZnFe 2 O 4 was used as the input material to test the feasibility of the new method, 70% Zn leaching efficiencies and the isolation of Fe in the residue through the formation of ferroferric oxide (Fe 3 O 4 ) were achieved at the optimal conditions of 260 °C, 6 M [NaOH], 10 g/L [C 6 H 12 O 6 ] n and 50 mL/g of L/S. Second, a leaching process of EAF dust was proposed using the following two procedures: (i) first leaching under normal pressure to dissolve zinc oxide (ZnO); and (ii) second leaching of the first leach residue under hydrothermal reduction conditions to dissolve ZnFe 2 O 4 . The leach liquor from the second step was recycled to the first step. Under optimum conditions, the leaching efficiencies of Zn during the first and second leaching were 66.4% and 69.3%, respectively. The total Zn leaching efficiency was calculated to be 89.7%, producing Zn-impregnated leach solution and a leach residue rich in Fe (up to 39.4 wt%) that are suitable as resources for a steel-making plant. However, this process also has its shortcomings owning to larger liquid-solid ratio in the leaching process. Overall, the study technically provides an alternative approach to improve the recycling of zinc and iron and effectively reduce environmental risks from EAF dust.
研究领域:
环境工程
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冶金工程
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资源循环利用
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清洁生产技术
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工业废物处理
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）