1. Structural transformation and dehydroxylation of clay minerals in lithium-bearing clay.
- Author
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Zuo, Kesheng, Wang, Hao, Xiong, Kun, Yu, Chen, and Cheng, Hongfei
- Subjects
FOURIER transform infrared spectroscopy ,NUCLEAR magnetic resonance ,MAGIC angle spinning ,KAOLINITE ,CLAY minerals ,CHEMICAL weathering ,ILLITE ,INFRARED spectroscopy - Abstract
Lithium (Li)-bearing clays have become new types of Li resources, and it is found that the evolution of the mineral structure in Li-bearing clay greatly restricts the extraction of Li. Herein, a Li-bearing clay from Guizhou Province, China, was studied using in situ thermogravimetry–differential scanning calorimetry–mass spectrometry–Fourier transform infrared spectroscopy (TG–DSC–MS–FTIR) (evolved gases),
27 Al and1 H magic-angle spinning nuclear magnetic resonance (MAS NMR), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The results showed that the Li-bearing clay contained illite, chlorite, kaolinite, pyrite, and anatase. The dehydroxylation reaction of the clay minerals occurred at 450 °C. CH2 , CH4 , C3 H4 , C6 H5 , and C8 H9 evolved during the roasting process. The AlO4 (OH)2 octahedra transformed to AlO4 tetrahedra due to the reaction between the reductive gases and the residual O in AlO5 . The effect of dehydroxylation on the structural stability of different clay minerals differed. After dehydroxylation, kaolinite became amorphous, chlorite reacted with 20% H2 SO4 , and illite remained stable during the roasting-H2 SO4 leaching process. The Li-leaching efficiency increased significantly after dehydroxylation and decreased sharply with the formation of mullite. [ABSTRACT FROM AUTHOR]- Published
- 2022
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