Influence of long-term water immersion on spontaneous combustion characteristics of Bulianta bituminous coal

Coal spontaneous combustion (CSC) is one of the main disasters occurring in underground coal mines. In this paper, the variation of CSC characteristics was analysed by investigating the changes in the microstructure of Bulianta (BLT) coal, which was subjected to long-term water immersion. After being immersed in water for 30-90 d, the amount of heat released from the combustion of the coal samples at low-temperature oxidation increased. In addition, because of the hydrolysis of the minerals in coal, multiple components were dissolved, which subsequently lead to the expansion and breakage of coal. The phenomenon further resulted in the increase of coal porosity with pore size greater than 10 nm, which enhanced the rate of the reaction between oxidants and coal. By contrast, the tensile strength of the immersed coal decreased significantly, and the entire coal mass is likely to be crushed into the fine lumps of varying particle sizes. [Received: 4 June 2015; Accepted: 25 November 2015]