Geochemical and Mineralogical Characteristics of the Li-Sr-Enriched Coal in the Wenjiaba Mine, Guizhou, SW China.

ABSTRACT

This paper reports the mineralogical and geochemical compositions of C6 coal in the Late Permian Longtan Formation of the Wenjiaba Mine, Northern Guizhou in southwest (SW) China. The geochemical and mineralogical studies are the basis for the potential recovery of critical metals. The Longtan Formation, which is one of the major coal-bearing strata in SW China, contains dozens of coal seams. C6 coal is the main mineable coal seam in the Wenjiaba Mine and the whole coalfield. Proximate and ultimate analyses, inductively coupled plasma mass spectrometry (ICP-MS) and X-ray fluorescence (XRF) spectrometry on trace and major element concentrations, and X-ray diffraction and SEM-EDS analyses were carried out. Results suggest that this anthracite coal is characterized by low ash yield and medium sulfur content. The minerals are mainly composed of clay minerals (kaolinite, chlorite, illite, and mixed-layer illite/smectite), pyrite, and carbonates. Lithium is significantly enriched in C6 coal, with an average of 124 µg/g, and it has a higher concentration in the lower portion of the coal seam than that in the upper one. Strontium is significantly enriched in samples WJB-05 and WJB-06, with concentrations of 3030 and 4580 µg/g, respectively, but it is normal or just slightly enriched in other benches of C6 coal. Additionally, Cu, Nb, and Ta are slightly enriched in the coal. Lithium, dominantly hosted by kaolinite in C6 coals, has a recovery potential. Celestine is one of the major Sr-bearing minerals in C6 coal.