The Study of the Critical Moisture Content at Which Coal Has the Most High Tendency to Spontaneous Combustion

Moisture has a complex influence on the spontaneous combustion tendency of coal. The exothermicity of four different ranks of coal (lignite, gas coal, fat coal, and anthracite) with different total moisture contents during the oxidation process was tested by TA-DSC (Thermogravimetric Analysis- Differential Scanning Calorimetry). It was found that, for different ranks of coal, the effect of the moisture content can be quite different and for the same rank of coal, different moisture contents will affect the coal's exothermicity in very different ways. In addition, the critical moisture content at which the coal is most highly prone for spontaneous combustion was also obtained. It was found that different ranks of coal have different critical moisture contents. For lignite and anthracite, the critical moisture content was 25% and 20%, respectively. For the gas coal and fat coal, the lower the moisture content is, the greater the chance for the coal to have spontaneous combustion.