Mineral composition and geochemical characteristics of the Li-Ga-rich coals in the Buertaohai-Tianjiashipan mining district, Jungar Coalfield, Inner Mongolia

Compared to common Chinese and worldwide coals, the studied Jungar coals are much more enriched in Al (4.4-6.1%), Li (70-79 mg/kg), and Ga (14-19 mg/kg). Titanium, P, Sr, Zr, Nb, Th, Ta, Hf, and rare earth elements (REEs) are also enriched in the studied coals to some extent. Aluminum in the coals mainly occurs in the form of kaolinite and boehmite, whereas, lithium may be associated with aluminosilicate minerals (kaolinite and illite if present) as well as svanbergite. Gallium principally occurs in kaolinite, and to a lesser extent, svanbergite. Strontium, P, and LREEs (La, Ce, and Rr, Nd and Sm) mainly present in svanbergite. The source of Li and Ga in Jungar coals is most likely from the Yinshan Oldland region, but there is also a possibility of migration from bauxite of the Benxi formation.