Study on the heat generation characteristics and critical oxygen concentration of Dafoshi coal based on programmed temperature experiment

To investigate the impact of oxygen concentration on the low-temperature oxidation characteristics of coal and determine the critical oxygen concentration for spontaneous combustion of Dafoshi coal, this paper takes the 40204 working face of this mine as the research object and conducts programmed temperature oxidation experiments under five oxygen concentration conditions: 3%, 6%, 11%, 16%, and 21%. The results show that a decrease in oxygen concentration increases the crossover temperature, with no crossover point observed at 3% oxygen concentration; the initial generation temperature of indicator gases increases and their concentration decreases, with a more significant inhibitory effect of low oxygen after 70 ℃; the oxygen consumption rate and heat generation rate decrease with a decrease in oxygen concentration, and the inhibitory effect of low oxygen becomes more pronounced after the dry cracking temperature. Comprehensively, the critical oxygen concentration for spontaneous combustion of Dafoshi coal is determined to be 6%, below which the coal spontaneous combustion process is greatly suppressed.