Differential thermal analysis (DTA) has been used as a method to study
the self-heating behaviour of fresh and oxidized coals. Oxidation was
performed in air at 200 degrees C for periods of up to 72 h. Six coal
s ranging from a High A Bituminous coal to a semi-anthracite were used
. As the rank of the coal increases, both the self-heating and the end
of combustion temperatures also increase. The total heat loss (area u
nder the DTA curve) increases with the rank of the coal. An increase i
n the self-heating temperature, a decrease in the temperature of the e
nd of combustion and a decrease in total heat flow were observed as a
consequence of coal oxidation. A relationship between the total heat l
oss and the calorific value as determined using the ASTM standard meth
od is pointed out.