Mode of Occurrence and Distribution of Critical Metal Lithium and Other Trace Elements during Coal Preparation from Jiashun High-Sulfur Coal in Guizhou Province, China

Abstract

During the Late Permian period, the coal from the Jiashun Mine in Xingren City, Guizhou Province, China, is characterized by a high sulfur (5.84%) and lithium (Li) (94.5 μg/g) content. Lithium is a critical metal in the context of global energy transition. Considering the importance of environmental protection and resource utilization, the mode of occurrence and distribution of trace elements in different coal preparation products were investigated. The obtained results indicated the following: (1) The minerals in Jiashun coal were mainly composed of veined and epigenetic pyrite, quartz, and kaolinite. Most of the minerals could be effectively removed from the cleaned coal through gravity separation. (2) The mode of occurrence of rare earth elements and yttrium (REY) in the coal was relatively complex, and they were mainly found in middlings from gravity separation and in flotation tailings. (3) The mode of occurrence of the trace elements in the coal significantly influenced their removal rate. The removal rate was significantly higher for trace elements removed through gravity separation compared to those removed using flotation. The trace elements mainly found in fine-grained minerals wrapped by organic matter or combined with organic portions had better removal results through flotation. The trace elements that occurred both in the minerals and organic matters had low removal rates (<25%) using two coal preparation methods. (4) Li was more enriched in the middlings from gravity separation (98 μg/g) and in flotation tailings (102 μg/g), reaching the marginal grade (80 μg/g) of Li in coal. (5) Li in Jiashun coal may be derived from intermediate-felsic rocks at the top of the Kangdian Upland and late hydrothermal solutions.