Assessment of auto-oxidation cum self-heating tendency of Indian coals by DRIFT studies

Coal self-heating, due to low temperature oxidation of coal, is generally considered to be the primary cause of spontaneous ignition. With the purpose of having a more definitive quantization of this subtle stage of coal oxidation, study on proneness to coal towards auto-oxidation, vis-a-vis self-heating phenomenon, has been carried out. Various methods like crossing point temperature (CPT), diffuse reflectance infrared fourier transform spectroscopy (DRIFT), differential scanning calorimetry-thermogravimetric analysis (DSC-TGA) and wet oxidation method has been used for comparative study. It is observed that though CPT values alone are adequately indicative and are consistent with actual field experience, the combination of CPT and DRIFT data complements each other very well to provide greater information for better prediction of proneness to auto-oxidation vis-a-vis self-heating phenomenon of coals. Other methods tried are found to be comparatively inadequate.