Mineralogical and geochemical characterization of coal debris from major coal fields in India: Implications on respirable dust hazards

Abstract

Coal mining activities have major impact on the surrounding regions through flying coal dust particles. In this study, we investigate the differences in mineralogy and geochemistry between the deposited coal dust and the respirable fractions of coal dust samples collected from the coal mining regions of Jharia and Raniganj coalfields in India. The coal dust samples were investigated in detail through various analytical techniques including FE-SEM, TGA, and particle size analyzer. The proximate analysis of the coal dust indicated that the ash content is 75%, moisture 0.5%, volatile matter 8.4%, and fixed carbon 16% in the Jharia coal fields, while the respective values of Raniganj coal values are 68.3%, 2.8%, 14.6%, and 14.2%. The average carbon content in the Raniganj coal dust particles is higher than that of Jharia (22.62 vs. 21.50%) and suggest that the coal dust particles were transported from the coal mining areas. The scanning electron microscopy images suggest that the coal dust samples have spherical and irregular morphologies. The carbon and sulphur in these samples were possibly derived from the organic matter of the coal materials, which were transported by air as dust particles. The particle size distribution of the coal dust samples revealed that 75–95% of these by volume are in the fraction of <600 μm. It can be inferred that the relatively fine particles of the coal dust samples contained 70% of ash comprising of mostly silica and clay as maximum respirable dust, which is hazardous to both human life and the environment. Our study provides insights into the air pollution and health risks around mining areas.