On the role of times to ignition in the thermal safety of transportation of bituminous coals

Previously presented results for the oxidation kinetics and hence the spontaneous combustion propensity of six Scottish bituminous coals are reappraised in terms of ignition times, an aspect not considered previously. All six coals could be considered unsafe to ship according to safety criteria based on the spontaneous combustion propensity, but at least two of them have ignition times so long that no incident would be expected on an export voyage. The test for assessing spontaneous combustion propensity does not alone appear to be an adequate criterion for safety in transport.