spontaneous heating; coal; oxidation heat; gas evolution; thermal analysis

Effect of bituminous coal pre-treatment was investigated to elucidate possible changes in oxidation behaviour of the coal lying in the centre of spontaneous combustion site and/or its vicinity. Pre-oxidation of coal at elevated temperatures (200, 250°C) and coal pre-heating under inert gas (nitrogen) were examined as procedures simulating possible effects on coal during underground mine fires. After the pre-treatments, coal samples were evaluated with respect to their susceptibility to oxidation using calorimetric determination of oxidation heats. Simultaneously, amount and composition of the gases indicating spontaneous combustion stage (CO, unsaturated hydrocarbons) evolved at temperatures 40 - 200°C were measured at continuous flow reactor. Significant change in the oxyreactivity for coal, pre-heated under inert gas, was ascertained.