Chemical leaching of an Indian bituminous coal and characterization of the products by vibrational s

High volatile bituminous coal was demineralized by a chemical method.The vibrations of the "aromatics" structure of graphite,crystalline or non-crystalline,were observed in the spectra at the 1600 cm-1 region.The band at 1477 cm-1 is assigned as VR band,the band at 1392 cm-1 as VL band and the band at 1540 cm-1 as GR band.Graphite structure remains after chemical leaching liberates oxygenated functional groups and mineral groups.The silicate bands between 1010 and 1100 cm-1 are active in the infrared (IR) spectrum but inactive in the Raman spectrum.Absorption arising from C-H stretching in alkenes occurs in the region of 3000 to 2840 cm-1.Raman bands because of symmetric stretch of water molecules were also observed in the spectrum at 3250 cm-1 and 3450 cm-1.Scanning electron microscopy analysis revealed the presence of a graphite layer on the surface.Leaching of the sample with hydrofluoric acid decreases the mineral phase and increases the carbon content.The ash content is reduced by 84.5wt％ with leaching from its initial value by mainly removing aluminum and silicate containing minerals.