Extraction of lithium from coal gangue acid leaching solutions via co-precipitation

作者：Jinpeng Qiao, Chao Kang, Yanze Wang, Sheng Dong, Mengyao Sun, Jianrong Liu, Hailiang Zhang, Chenlong Duan · 发表于：International Journal of Coal Preparation and Utilization · 年份：2025 · DOI：10.1080/19392699.2025.2477546 · 被引用次数：3 · 研究领域：Extraction and Separation Processes、Metal Extraction and Bioleaching、Minerals Flotation and Separation Techniques

With the surging demand for lithium, extracting lithium from coal gangue has gained significant attention. However, current extraction methods remain complex and expensive. This study proposes a novel aluminum-lithium co-precipitation technology for efficient lithium extraction from coal gangue. The roasted coal gangue was leached with sulfuric acid to obtain an aluminum-rich leaching solution. The pH of the solution was precisely controlled by adding the alkali solution, which converted Al3+ in the leaching solution into amorphous Al(OH)3. Li+ was selectively adsorbed by in-situ precipitation. Under optimized precipitation conditions (Na/Al molar ratio: 3.6, NaOH concentration: 2 mol/L, drop rate: 15 mL/min, reaction temperature: 50℃), the lithium precipitation rate reached 88.29%. The coprecipitates were roasted and water-leached to separate aluminum and lithium, achieving a lithium leaching rate of 89.40%. They primarily consisted of Al2SO4(OH)4·7 h2O, Li2Al4(OH)12SO4·xH2O, and amorphous Al(OH)3. Their surface featured irregular small particles and a highly porous structure. As the solution pH increased from 3.5 to 10.7, the amorphous aluminum hydroxide gradually transformed into a bayerite structure.