SPONTANEOUS COMBUSTION OF COAL AND EFFECTING FACTORS

Coal tends to adsorb oxygen and oxidize due to its structure. Spontaneous combustion mechanism of coal is very complicated, and still this mechanism is not completely understood. However, coaloxygen compound theory is widely accepted by researchers nowadays. According to this theory, spontaneous combustion consists of slow oxidation, accelerating oxidation and rapid oxidation stages. In these stages, the physical oxygen adsorption, chemical oxygen adsorption and free radicals reactions are the dominant mechanisms, respectively. Spontaneous combustion of coal can occur without any external impact anywhere coal and / or coal wastes exist. Nowadays, its revealed that some common thoughts about the effecting parameters on spontaneous combustion of coal are wrong. For example; spontaneous combustion of coal does not occur only in low rank coals, and high pyrite content coals may have low spontaneous combustion tendency or coal mines which were determined as not risky can unexpectedly combust. Therefore, spontaneous combustion tendencies of coals must be determined; all stages such as mining, stockpile design and transportation must be planned in detail; continuous monitoring and emergency response plans must be arranged in case a spontaneous combustion