ABSTRACT

The spontaneous combustion behaviors of pulverized coal including anthracite, coking coal, nonstick coal and lignite were analyzed by TG-FTIR. A kinetic analysis was performed by the Coats-Redfern and Achar methods. The characteristic temperatures of coal combustion were classified for five key temperature points: maximum desorption of gases and evaporation of water, minimum mass loss rate at low temperature, ignition point, maximum mass loss rate and terminal residual. It was described in detail the correspondence between every key temperature point and coal grade through TG/DTG test results and the industrial and element analyses of four coal samples. Combined with the DSC test results, the effect of coal grade on coal spontaneous combustion characteristics was further revealed. With the increase of temperature, the evolution mechanism of index gases (CO₂, CO, CH₄ and H₂O) was revealed with different grades of coal during spontaneous combustion through FTIR spectroscopy. The activation energy and lnA during the combustion stage were calculated by the Coats-Redfern (integral) and Achar (differential) methods. The best mechanism function corresponding to anthracite, coking coal, nonstick coal and lignite was respectively obtained, and the influence of coal grade on activation energy and frequency factors (A) was analyzed.