Fire Safety Science Digital Archive

To identify an effective inhibitor to retard the self-heating and spontaneous ignition of coal, the effect of several retardants on bituminous coal has been investigated experimentally in a temperature controlled oven. The activation energy of coal treated with retardants has been evaluated over the temperature range from 60 OC to 220 OC using the Frank-Kamenetskii model and the rate of temperature rise. One retardants was found to increase the activation energy by up to 20 - 57 kJ/mol for different particle sizes of the coal. Various factors influencing the inhibition effect are considered. On the basis of experimental results, a kinetic interpretation of the retardation mechanism is put forward involving both radical reaction and active centre theories. It has been observed that there are possibly two regimes for the oxidation of a bituminous coal in the temperature range studied, viz., a chemically controlled regime and a combination of pore-diffusionally and chemically controlled regime. Finally, the possibility of using DDS-series inhibitors in practical situations is discussed.