Occurrences of phosphorus in coal of Raniganj Coalfield, Damodar Coal Basin, India: insights from petrographic and characterization studies

Coal is a significant energy resource for global energy production from thermal power plants. The phosphorus content in coal affects the coal-based power plant’s boiler system and significantly influences steel-making industries. The present study comprises the characterization of 48 coal samples each from the 12 coal mining areas in Raniganj Coalfield, Damodar Coal Basin, India. Both semi-coking and noncoking coal type with high ash were observed and the phosphorus content determined using inductively coupled plasma-optical emission spectrometry, found the highest concentration of phosphorus is 0.37% (coal basis). The concentration of phosphorus is influenced by the mineral matters’ composition in coal, observed correlation coefficient of r = 0.8. The maceral compositions, mineral matters, and phosphorus bearing minerals were examined using optical microscopy, and scanning electron microscopy. It was observed that the fusinite and semifusinite macerals are abundant in phosphorus-rich coal where the clay minerals are associated with them, which substantially influences phosphorus deposition in the area. Kaolinite minerals were identified by X-ray diffraction analysis and the oxide minerals (P2O5, Al2O3) through X-ray fluorescence analysis. Hence, both organic and inorganic sources are mainly responsible for the occurrence of phosphorus concentration in the areas.