A sustainable method for lithium recovery from waste liquids: Thermodynamic analysis and application

• Published in: Journal of environmental chemical engineering 2024-02, Vol.12 (1), p.111814, Article 111814
• Main Authors: Lv, Yingwei, Ma, Baozhong, Liu, Yubo, Wang, Chengyan, Chen, Yongqiang
• Format: Article
• Language: English
• Subjects: Conversion; Lithium; Precipitation; Recycling; Thermodynamics
• ISSN: 2213-3437; 2213-3437
• DOI: 10.1016/j.jece.2023.111814

In this study, lithium was efficiently enriched and recovered from low concentration waste liquids by sodium phosphate precipitation and wet conversion. Firstly, the efficient extraction of lithium at low concentration was realized based on the lower solubility of lithium phosphate. The factors involved in the lithium phosphate precipitation process by sodium phosphate were systematically investigated, and it was discovered that the high temperature process promoted the formation of lithium phosphate, with the lithium precipitation rate reached 94.32% under optimal conditions. The feasibility of the conversion of lithium phosphate into lithium chloride solution and iron phosphate by ferric chloride solution was analyzed by thermodynamic study. The experimental results also further confirmed that the lithium conversion rate was as high as 96.06% when the reaction temperature was 25 °C and the pH of the system was 2. The conversion process achieved the enrichment of lithium from low to high concentrations, avoiding the high energy consumption caused by conventional evaporation and concentration. More importantly, the alkaline leaching of the converted residue realized the separation of phosphorus and iron sources, and then the re-synthesis of ferric chloride solution and sodium phosphate reagent was accomplished by acid leaching and crystallization, respectively, allowing for reagent recycling in the lithium extraction process. The proposed process is expected to provide a green and sustainable route for the recovery of low concentration lithium from waste liquids. •Efficient extraction of lithium from low concentration solutions was enabled.•The wet conversion process of lithium phosphate was analyzed by thermodynamics.•The extraction process achieved the recycling of iron and phosphorus.•The battery grade lithium carbonate product was prepared.