The Effect of Pore Volume of Hard Coals on Their Susceptibility to Spontaneous Combustion

Table 1

Classification of coal by a susceptibility of spontaneous combustion.

Spontaneous combustion index Sz^a  (K/min)	Activation energy of coal oxidation 𝐴; (kJ/mol)	Group of spontaneous combustion	Evaluation of a susceptibility of coal to spontaneous combustion
≤80	>67	I	Coal of a very low spontaneous combustion susceptibility
	46–67	II	Coal of a low spontaneous combustion susceptibility
	<46	III	Coal of a medium spontaneous combustion susceptibility
>80 and ≤100	>42
	42 or less	IV	Coal of a high spontaneous combustion susceptibility
>100 and ≤120	>34
	34 or less	V	Coal of a very high spontaneous combustion susceptibility
>120	No standarization