Spontaneous Combustion in Coals - A Panacea

Lower Condwana coal samplcs from thc Ib-valley, the Talcher coalfield and the Raniganj coalfield were compared with the Tertiary coals of Upper Assam, Nagaland and Arunachal Pradesh by their chemical data in relation to crossing point temperature, petrography and rank. Previous works of the author as well as research on spontaneous combustion of coals by others till today, has not been successful to pronounce one single parameter to know the spontaneous combustibility character in coals. The reason for spontancous combustion varies from coal to coal in different coalfields because of the complexity of the coal composition.

Thc present paper asserts that any one of the two parameters such as volatile matter (calculated) and calorific value (calculated) can conveniently bc used to know the degree of spontaneous combustion in coals.

It is proposed that the coal could be considered as highly prone to spontaneous combustion if the value of volatile matter (calculated) exceeds 40, moderately prone to spontaneous combustion if thc value in between 40 and 32 and lcast prone if below 32. Corresponding calorific values (calculated) have becn fixed as less than 8000 kcal/gm, 8000 to 8500 kcal/gm, and more than 8500 kcal/gm. To achieve these results, the expensive and extensive process of ultimate analyses could be avoided. Use of graphs based on coefficient of correlation, volatile matter (experimental) obtained by proximate analysis will give an approximate value of volatile matter (calculated) and calorific value (calculated) to indicate thc dcgree of spontaneous combustion.