Characteristics and Effects of Spontaneous Heating in Barmer Lignite - A Case Study

Spontaneous heating is a characteristic of all coals. The incubation period of any coal, however, varies widely, depending upon a variety of factors, chief among them being, degree of maturity of the coal, moisture content, presence of sulphides, ambient temperature and conditions of partial ventilation. The only lignite deposit presently being worked by surface mining in Rajasthan, is near village Giral in Barmer district. The lignite of this deposit, apart from high moisture content, has a very high sulphur content, varying from a minimum of around 3 percent to a maximum of around 12 percent; average being around 5.5 percent. Further, in Barmer, because of desertic climate, the ambient temperatures as well as the wind velocities are very high, for most part of the year. As a consequence of all these factors, it has been seen that the incubation period of Giral lignite, varies from as low as 7 days to as high as 45 days. Such a low incubation period poses new challenges in lignite mining, overburden dumps management, stacking and transportation, utilization of the lignite and environment management around the mine.