Early prediction is one of the key technologies to the prevention and extinguishment of spontaneous combustion of coal. The aim of this study was to propose a type of scientific and convenient forecasting indicator for initial spontaneous combustion of coal in the gob area. The authors developed the calculation model of carbon monoxide (CO) concentration in the air return corner based on the generation mechanism, sources, and influencing factors of CO. The parameters obtained from both large-scale coal self-heating experiment and in-situ observation of four collieries in Yuanyang lake mine area were used to calculate the extreme value of CO concentrations on various stages of spontaneous combustion. The established indicators were applied to specific coal mine scenarios and combined with the in-situ measurements. It demonstrates that this method has provided the scientific guidance for safer exploitation on coal mines. Furthermore, the main reasons of unstable CO concentrations in the return corner and its relationship with prevention measures were also examined. In summary, the results showed that the forecasting indicators established can meet the requirements of identification of spontaneous combustion potential of coal in Yuanyang lake mine area.

Coal resources are rich in China. They are mainly concentrated in the northwest region. But these resources also make the situation of spontaneous coal combustion hazards most serious in this area. Affected by the arid and semiarid climate, the water resource in this area is relatively scarce. In order to improve the utilization rate of water, a macromolecule colloid for coal mine fire fighting was developed in this research. The main components of the macromolecule colloid and the principle of gel formation were analyzed. The physical and chemical properties of the macromolecule colloid were analyzed by the time of gelation and the water loss. The water content of the macromolecule colloid was as high as 99%. The inhibition performance of the macromolecule colloid on coal fire was studied by the programmed heating device. The experimental results show that the macromolecule colloid has a significant inhibitory effect on the heating rate, oxygen consumption rate, and gas production rate. It inhibits the coal-oxygen composite by increasing the activation energy (E_a) of coal, which also has the effect of wrapping coal to isolate oxygen. The inhibition performance of the macromolecule colloid on coal fire disasters is better than that of water, water glass, loess compound colloids, and other traditional fire-extinguishing materials.

To investigate the actual gas explosion and propagation laws in the roadway of an underground mine, experiments were conducted in a standard 19-L tube of rectangular section to provide a comprehensive understanding of the effects of carbon monoxide (CO) addition and obstacles placed on the flame propagation of explosions from methane–air mixtures at different conditions. The flame structure, flame propagation speed, heat loss, and explosion pressure were used to reflect the explosion behaviors of the premixed flame. The experimental results indicate that the enhancement and attenuation of the explosion pressure wave are significantly influenced by an obstacle. The existence of obstacles changed the trend of classical pressure rise, thus forming a first pressure peak. In addition, the position close to the obstacle presented a higher explosion pressure. Under 7 vol.% and 9.5 vol.% CH₄ conditions, the increase of CO (from 0 vol.% to 2 vol.%) promoted explosion flame propagation. However, the CO exhibited a clear negative effect on the rate of flame propagation due to exacerbated O₂ depletion of 11 vol.% CH₄, and the negative effect enhances with CO increased. Besides, when the CO addition increased, the flame tended to more instability and more brightly. For heat loss, with the increase of CO content in mixed gases, there was a slight promoting, constant and inhibiting effect for 11 vol.%, 9.5 vol.%, and 7 vol.% CH₄, respectively. These results are of fundamental importance for the prevention and mitigation of gas explosion in underground mines and other industrial scenarios.