Spontaneous combustion of carbonaceous stockpiles. Part I: the relative importance of various intrinsic coal properties and properties of the reaction system

The first part of this paper investigates a range of coal properties that were considered to be the most critical in terms of heat 'generation' in a bulk coal medium. Certain properties, such as the heat capacity, the heat of reaction with oxygen and the activation energy for this reaction, were found to vary to a relatively minor degree for coals of varying rank and geological origin. However, rates of reaction with oxygen were found to vary by orders of magnitude for different coals. The reaction kinetics is consistent with a diffusion-limited shrinking-core model. A study of the coal properties that most strongly influence these rates of reaction is the subject of part two of this paper.