Assessment of Spontaneous Heating Susceptibility of Some Indian Coals using Experimental Techniques

Abstract

Coal mine fire is a major problem worldwide and has been a great concern both for the industry and researchers in this field. Majority of fires existing today in different coalfields are mainly due to spontaneous combustion of coal. Most mine fires start very small and gradually expand in size, thereby, causing loss of natural property, serious environmental pollution of land, water and air and considerable economic losses to the organisation. Although much research has been done on the subject, a proper assessment of the spontaneous heating susceptibility of coal needs to be done so that mine operators are notified well in advance and plan the working properly. Therefore, the determination of susceptibility of coals to spontaneous heating and their classification is essential to plan the production activities and optimise coal mine production within the incubation period.

EXPERIMENTAL INVESTIGATION

To carry out this study, coal samples were collected from the field using channel sampling. Samples from many seams from different coal mines were collected, sealed in air tight containers and carefully brought to the laboratory for further preparation. The collected samples were subject to coning, quartering and grinding. They were then screened to a size of -212 micron and placed inside small air-tight bags. Various field visits were also made to know about the actual conditions that exist in the working conditions and which could be included in the study, during the analyses.
The Proximate analysis for determination of ash, volatile matter and moisture Content was performed to determine the intrinsic properties of coal. Gross calorific values of coals were found out using Bomb Calorimeter. The results of proximate analysis and calorific value are as presented in Table1. The spontaneous heating susceptibility tendency of the coal samples were determined using crossing point temperature (CPT), differential thermal analysis (DTA) and wet oxidation potential difference. The results of these analyses are presented in Table 2. Correlation between the intrinsic properties and susceptibility indices were also carried out.