Abstract
Aluminum electrolyte is a necessity for aluminum reduction cells; however, its stock is rising every year due to several factors, resulting in the accumulation of solid waste. Currently, it has become a favorable material for the resources of lithium, potassium, and fluoride. In this study, the calcification roasting–two-stage leaching process was introduced to extract lithium and potassium separately from aluminum electrolyte wastes, and the fluoride in the form of CaF2 was recycled. The separation behaviors of lithium and potassium under different conditions were investigated systematically. XRD and SEM–EDS were used to elucidate the phase evolution of the whole process. During calcification roasting-water leaching, the extraction efficiency of potassium was 98.7% under the most suitable roasting parameters, at which the lithium extraction efficiency was 6.6%. The mechanism analysis indicates that CaO combines with fluoride to form CaF2, while Li-containing and K-containing fluorides were transformed into water-insoluble LiAlO2 phase and water-soluble KAlO2 phase, respectively, thereby achieving the separation of two elements by water leaching. In the second acid-leaching stage, the extraction efficiency of lithium was 98.8% from water-leached residue under the most suitable leaching conditions, and CaF2 was obtained with a purity of 98.1%. The present process can provide an environmentally friendly and promising method to recycle aluminum electrolyte wastes and achieve resource utilization.
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Data availability
The datasets used and analyzed during the current study are available from the corresponding author on reasonable request.
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Funding
This research work was financially supported by the National Natural Science Foundation of China (Grant numbers 51874086, 51804071, 51904192, 51434005, 51529401, 51804069, 51804070); the Fundamental Research Funds for the Central Universities (Grant number N2025024); the Liaoning Natural Science Foundation (Grant number 2022-MS-121); and the Ministry of Education—Weiqiao industrial program (Grant number 2021021800101).
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Shaohua Wu: conceptualization, investigation, methodology, writing—original draft. Wenju Tao: writing—review and editing, supervision, validation, formal analysis, visualization. Hui Ge: conceptualization, writing—review and editing, formal analysis, data curation. Jiaxin Yang, Jiaming Li, **gui He, and Youjian Yang: investigation, methodology, writing—review and editing, formal analysis. Zhaowen Wang: project administration, supervision, validation, formal analysis, visualization.
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Wu, S., Tao, W., Ge, H. et al. Stepwise extraction of lithium and potassium and recovery of fluoride from aluminum electrolyte wastes through calcification roasting–two-stage leaching. Environ Sci Pollut Res (2024). https://doi.org/10.1007/s11356-024-34129-5
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DOI: https://doi.org/10.1007/s11356-024-34129-5