Investigation of the spontaneous combustion susceptibility of coal using the pulse flow calorimetric method: 25 years of experience

The paper summarises 25 years of experience with pulse flow calorimetry (PFC) as a method to assess the potential of coals to spontaneously heat up using the values of oxidation heat q30 (W kg−1). During the period, about 300 coals of various rank and with natural moisture content were investigated, the maximum propensity to oxidation being found in subbituminous coals with moisture content of about 20%. The highest value of oxidation heat q30 was found to be 10.5 W kg−1. Oxidatively altered bituminous coals are presented as coals of evidently increased ability to oxidize, and the reasons for the increased oxyreactivity are reported. Limiting values of q30 heat are then given to rank the coals according to the categories of self-heating risk. Finally, a comparison between oxidation heat q30 and the values of the initial rate of heating (IRH) of adiabatic oxidation tests is presented.