Self-Heating Behaviour of Heat-Affected Coal

Adiabatic oven testing of heat-affected and normal coal from the same location at Mandalong Mine shows substantial differences in intrinsic self-heating rates and self-heating behaviour. While initial self-heating rates of the heat-affected coal are greater than normal coal under site conditions, there is no sustained self-heating to thermal runaway due to a decrease in the number of reactive sites remaining in the heat-affected coal and greater inaccessibility to those sites that do exist. This behaviour is attributable to the vesicular nature of the heat-affected coal contributing to easy access to open pores resulting in the initial burst of self-heating. However, the thermal alteration of the coal also contributes to destruction of reactive sites and makes access to the remaining reactive sites in the micropore system of the coal more difficult.