Assessment of Spontaneous Heating of Coals by Thermal Analysis Technique

Abstract

Coal mine fire is a major issue not only in India but also all over the world. But around 80% coal fires occurring in Indian coal mines are due to spontaneous heating of coal. Due to coal fire many precious lives are lost, and economical loss also occur to the organization and to the nation. With rapid growth of India, the requirements for energy are increasing rapidly for industrial sectors and domestic use. To cater the increased demand for energy, we are relying on thermal power plants. So more stress is now given on high production of coal. With increase in coal production the spontaneous heating incidents are also bound to increase. That’s why special attention needs to be given for more study on spontaneous heating susceptibility of coal. So that early precautionary measures could be taken to prevent the coal to catch fire. In this study, 26 coal samples were collected from different coal fields of India viz. MCL, SECL, SCCL, ECL, CCL, BCCL, NECL, NCL. All the samples of coal were studied using Differential thermal analysis and proximate analysis was also done in order to get the intrinsic properties of the coal. Using the obtained thermogram from DTA study, the coal samples were classified into three categories based on their potential to spontaneous heating. Correlation study was done in order to find the correlation in between intrinsic properties of coal and the key indicators of spontaneous heating from thermogram viz. onset temperature, slope IIA, slope IIB, overall slope II. From the study of the thermogram, 14 samples were found to be highly prone to spontaneous heating while rest 6 each were moderately susceptible and poorly susceptible to spontaneous heating. The slope value of Stage II A is a better indicator of determining spontaneous heating. The slope of stage IIA was found to be higher for highly susceptible coals. The correlation study confirmed that the moisture content of coal is a key factor affecting the spontaneous heating of coal.