Effect of elemental composition and phase transformation on lithium leaching behavior of micas in calcination-acid leaching process

• Published in: Applied clay science 2024-11, Vol.260, p.107522, Article 107522
• Main Authors: Zuo, Kesheng, Zhou, Xuanping, Wang, Hao, Li, Zhihang, Xiong, Kun, Cheng, Hongfei
• Format: Article
• Language: English
• Subjects: Calcination; Dehydroxylation; Leaching; Lithium; mica
• ISSN: 0169-1317
• DOI: 10.1016/j.clay.2024.107522

Lithium (Li)-bearing clays have emerged as new types of Li resources. The structure and elemental composition of clay minerals play a crucial role in determining the Li leaching efficiency. The elemental composition and structural transformation of Li-bearing mica from Inner Mongolia (IMS) and Jiangxi (JS), China, were studied during the calcination-leaching process by using X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR) and electron microprobe analysis (EMPA). The findings indicate that Mica is the predominant Li-bearing mineral in both IMS and JS. Notably, the IMS mica contains a significantly higher concentration of fluorine compared to the JS mica. Fluorine exerts a minor inhibitory effect on Li leaching, whereas the hydroxyl group (OH) significantly inhibits the leaching of Li from mica. The removal of residual oxygen atoms post-dehydroxylation is crucial to extract Li from mica. Both defluorination and dehydroxylation reactions occur within the temperature range of 800 °C to 900 °C. When calcined at 900 °C, the IMS mica was transformed into sanidine, while the JS mica was transformed into microcline. The acid leaching of products calcined at this temperature represents a process that further disrupts the residual mica structure and facilitates a cation exchange reaction. •Fluorine acts as a mild inhibitor for the leaching process of lithium from mica.•OH exerts a significant inhibitory influence on the leaching of lithium from mica.•Defluorination and dehydroxylation reactions occur in the range of 800 °C to 900 °C.•Removal of residual O post-dehydroxylation is crucial to extract lithium from mica.