Critical particle size analysis of gas emission under high-temperature oxidation of weathered coal

To study the effects of particle size on gases emitted from weathered coal under high-temperature oxygen deficiency, we investigated the macroscopic spontaneous combustion characteristics of weathered coal with various particle sizes during high-temperature oxidation. The gas concentration obtained from weathered coal of different particle sizes through oxidation from normal temperature to 600 degrees C was tested using a self-developed high-temperature program experiment system, and the variation law of the indicator gas was analyzed. The thermokinetic parameters of weathered coal were calculated in four reaction stages. The results revealed the different experimental phenomena of the coal sample of each particle size. The temperature-increase rate of weathered coal with different particle sizes was presented as a growth trend, and a noticeable stage was observed during the growth process. The concentration of indicator gas neither increased nor decreased monotonically with the change in the particle size. A particle size of 3 mm was obtained as the critical particle size during the high-temperature oxidation of weathered coal. The experimental results provided a pivotal theoretical basis for the early prediction and scientific prevention of the spontaneous combustion of weathered coal during open-pit mining and shallow coal seams. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

The study investigated the effects of particle size on gases emitted from weathered coal under high-temperature oxygen deficiency, revealing that the concentration of indicator gas did not monotonically increase or decrease with the change in particle size. A particle size of 3 mm was determined to be the critical size during high-temperature oxidation of weathered coal. The results provided a pivotal theoretical basis for the early prediction and scientific prevention of the spontaneous combustion of weathered coal.