An Investigation into Spontaneous Heating Characteristics of Coal and its Correlation with Intrinsic Properties

Abstract

Spontaneous heating property of coal is a matter of prime concern in mining industry. Spontaneous combustion of coal has caused many mine fires leading to huge loss of coal and also loss of many human lives. Storage and transportation of coal requires knowledge about the spontaneous heating liability of coal, as it starts degrading on coming in contact with air. Numerous studies and research work has been done to understand the mechanism of spontaneous heating and its relation with coal’s intrinsic properties. The present study presents the correlation of spontaneous heating susceptibility of coals belonging to different coalfields of India with their intrinsic properties. The coal samples were collected from different Indian coalfields. Twelve coal samples were collected from Mahanadi Coalfield Ltd. (MCL), Singareni Collieries Company Ltd. (SCCL), Bharat Coking Coal Ltd. (BCCL) and North Eastern Coal Fields Ltd. (NECL). The Intrinsic properties were determined by carrying out – proximate analysis, Aliphaticity from Fourier transform infrared spectroscopy (FTIR) and Gross calorific value (GCV) using Bomb calorimetry. The susceptibility indices were found using Crossing point temperature (CPT) and Wet oxidation potential difference (WOPD). The correlation of intrinsic properties and susceptibility indices is done using both Simple linear regression and multiple linear regression. The results for intrinsic properties and the susceptibility indices are presented in table 1. The simple linear regression analysis showed that the moisture, ash and aliphaticity as compared to other intrinsic properties are a better indicator of spontaneous heating as they have better correlation with CPT and WOPD. Therefore, aliphaticity is suggested as a good indicator of spontaneous heating susceptibility. On multiple linear regression analysis strong correlation was found between moisture, ash, aliphaticity and both the susceptibility indices.