A numerical model of the spontaneous combustion of coal has been developed and is being used to investigate the nature of self-
heating in underground coal mines. Results to date confirm the complexity of the self-heating reaction in coal and illustrate the
impact of the factors such as the coal reactivity, mass and airflow through the coal pile. Subtle differences in the chemical, physical
and environmental conditions and make a significant difference in the development of a high temperature self-heating or a low
temperature benign condition, the subtlety escaping normal underground observations. Additional work is planned to investigate
the thresholds for such factors in the development of spontaneous combustion and it the implications for detection by gaseous
Products.