RATE OF OXIDATION OF CHAR AND COAL IN RELATION TO THEIR TENDENCY TO SELF-HEAT

As part of a study of self-heating tendencies of Australian coals and chars, the rates of oxidation of fresh and weathered chars and a weathered coal have been measured in dry (fresh char only) and moist air over the temperature range 45 to 94 °C. The oxidation of the weathered materials has an apparent activation energy lying between 63.9 and 69.0 kJ/mol which is independent of their moisture content. However, the rate of oxidation of char increases with increasing moisture content and decreases with increasing carbonization temperature of the parent coal, and with the extent of the char's weathering. Indeed, under adiabatic conditions it is shown that weathering or progressive oxidation, which conforms to the Elovich relation, may largely offset any substantial self-heating of char (or coal) caused by the accelerating effect of temperature. © 1979.