Thermal and Spectral Studies to Assess the Spontaneous Combustion Propensity of Coal Seams of Raniganj Coalfield, India

The extraction of coal from Raniganj Coalfield (RCF) plays a vital role in the country’s industrial growth. The mechanisation of underground coal mines of RCF for excavation raises several issues in India, namely: multi-seam workings, upper seam worked-out areas, strata management, subsidence, ventilation, heat, humidity, spontaneous heating, and mine fires. This research is focused on studying the spontaneous combustion characteristics of ten RCF coals by investigating the CPT, TGign and FTIR, along with intrinsic properties of coal, viz. proximate analysis. The proximate analysis and spontaneous combustion study reveal that seven samples have optimum moisture (4-8 %), high volatile matter content (>30.0%), low CPT (<160°C) and TGign (<290°C) value. The remaining three samples have low moisture (<4.0%), low volatile matter content (<25.0%), high CPT (>180°C) and TGign (>320°C) values. FTIR study of these coals reveals that the same samples have quality organic functional groups (mainly including alcoholic group, carboxylic group, aldehyde group, ketonic group, alkene and alkyne group, etc.) which enhance the propensity of coal to spontaneous combustion. Based on all the results, it was observed that RCF coal has a critical issue of spontaneous combustion in many coal seams, which ultimately leads to coal mine fire in such cases. Major Findings: Coal samples of RCF with VMd > 30%, Mad range 4 to 8 %, CPT < 160 °C, TGign < 290 °C are more susceptible to spontaneous combustion. This finding is also confirmed by FTIR analysis of coal samples.