Abstract:
The southern Junggar coalfield contains abundant coal resources and is an important component of the large coal base in Xinjiang, China. In this study, we undertook a multi-proxy study evaluating macerals, vitrinite maximum reflectance, ash content, volatile matter content, sulfur content, hydrogen and carbon atomic ratio, chlorine, fluorine and arsenic elements from the coal seam 5 to explore the clean potential and clean utilization method of the coal seam 5 in Tunbao coal mine, according to the evaluation index systems of coal clean utilization potential and coal direct liquefaction. This paper also identified the depositional environment of No. 5 coal seam. The ash yield, maceral characteristics (high inertinite content,
V/
I ratio) and major elements (ash component index, CaO/MgO, SiO
2/Al
2O
3) of coal seam 5 in Tunbao Coal Mine reflect that coal seam 5 was formed in a weak oxidation environment with warm and humid, shallow water cover and large changes in hydrodynamic conditions. The coal seam 5 of Tunbao coal mine has the characteristics of relatively low chlorine and arsenic contents, as well as relatively high ash, sulfur and fluorine contents. The ash content is the main obstacle to the clean utilization of coal in Tunbao coal mine. The research results show that clean coal grade is of category III for raw coal, belonging to relatively unclean coal. The coal types of coal seam 5 are mainly brown coal, long-flame coal, and non-caking coal. The content of inertinite is relatively low, and it has the characteristics of ultra-low ash content, high volatile content and high hydrogen and carbon atom ratio. Floating coal meets the evaluation criteria for direct liquefaction coal and is suitable for use as class II direct liquefaction coal.