Spontaneous combustion in coats - A panacea

Lower Gondwana coal samples from the 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 spontaneous combustion varies from coal to coal in different coalfields because of the complexity of the coal composition. The present paper asserts that any one of the two parameters such as volatile matter (calculated) and calorific value (calculated) can conveniently be 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 the value in between 40 and 32 and least prone if below 32. Corresponding calorific values (calculated) have been fixed as less than 8000 kcal/gm, 8000 to 85,00 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 the degree of spontaneous combustion.