Steady behaviour of long duration in the spontaneous heating of a bituminous coal

So-called steady state behaviour in laboratory scale self-heating of solid substrates such as carbons and cellulosics has rarely if ever been truly steady, but has displayed a maximum in the temperature history. This is due to volatiles and/or to porosity. In this paper it is argued that the self-heating of a bituminous coal will, at the temperatures concerned, be free from these effects and will therefore display genuinely steady behaviour. This assertion is tested by experimental work on a Scottish bituminous coal, in which sustained steady behaviour is indeed observed, with a heat release rate calculated to be approximate to 3 kW m(-3).