Laboratory Study on the Spontaneous Combustion Propensity of Lignite Undergone Heating Treatment at Low Temperature in Inert and Low-Oxygen Environments

Abstract

This laboratory study investigated the spontaneous combustion propensity of coal undergone heating treatment at low temperature (<200 °C) in N 2 , CO 2 , and the air of 10% O 2 environments. The investigations include the changes in the emission of carbon oxides, oxygen consumption, activation energy, infrared spectroscopy, and pore structure before and after the treatment of lignite. The results show that in comparison to the original coal, the treated lignite is more easily oxidized, produces more carbon oxides at low temperature, and has more C−O structure, less heteroatoms substitution structure and free OH content, larger pore volume, and high porosity and permeability. Porous structure analysis reveals that the treated lignite produces a variety of pores larger than 10 nm, and these pores are conductive to the movement of the oxygen molecules in lignite and the chemical reaction between oxygen molecules and active groups on the surface of lignite. This study concludes that lignite undergoing heating treatment at low temperature in inert environments increases its spontaneous combustion propensity.

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