Study on the distribution law of spontaneous combustion danger zone of coal gangue pile under the influence of wind speed
The distribution of spontaneous combustion risk areas in the coal gangue pile is significantly influenced by external environmental wind speed.To investigate the influence of wind speed,this research begins with a theoretical analysis from the perspectives of permeation fields,oxygen concentration fields,and temperature fields to elucidate the mechanism of spontaneous combustion.Subsequently,thermal gravimetric analysis is conducted on coal gangue samples to determine crucial temperature thresholds during the self-ignition process,which serve as demarcation criteria for spontaneous combustion risk areas.Finally,simulations are performed using FLUENT software to explore changing patterns within the tripartite fields of coal gangue piles under different environmental wind speeds.This method enables the calculation of dimensions for spontaneous combustion risk areas that are subsequently subjected to curve fitting.Moreover,on-site measures for management and efficacy validation are undertaken.The research findings reveal that within coal gangue piles,there are localized gradual combustion phenomena accompanied by a rapid increase in conversion rates when the post-θ2 temperature reaches the threshold of 332.42 ℃.Therefore,it is necessary to adopt θ2 temperature thresholds as criteria for identifying areas at risk of spontaneous combustion.Additionally,the dimensions of these risk areas in coal gangue piles show an initial enlargement followed by a gradual reduction with increasing wind speed.At a wind speed of 1.65 m/s,the area reaches its maximum extent at 75.25 m2.When the slope surface of the coal gangue pile is covered with a layer of topsoil that is 0.5 m thick for 30 days,the temperature within the risk area drops to a range between 202 ℃ and 232 ℃,indicating effective management measures have been implemented.These research outcomes are highly significant for preventing and managing spontaneous combustion in coal gangue piles in China.
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