Study On Coal Spontaneous Combustion Law And Fire Control Technology Of Small Coal Pillar Working Face In Yangchangwan Mine,Ningxia

The phenomenon of coal spontaneous combustion generally occurs in the process of coal mining,and the technology of fully mechanized top coal caving and driving along the goaf is widely used in thick coal seam,and the fire-fighting problem of small coal pillar working face is serious.Although driving along the goaf can improve the recovery rate of resources,in the process of mining,the small coal pillar of roadway protection is easily affected by mining stress,which makes the coal pillar compressed and deformed,resulting in cracks.At present,many scholars have studied the surrounding rock stress,mining influence and surrounding rock control technology of the small coal pillar along the goaf,but few have systematically studied the influence of the fire-fighting problem of the narrow coal pillar working face.For example,the gas intrusion in the adjacent goaf caused by the crack of the small coal pillar,the air leakage in the working face,the temperature rise and spontaneous combustion of the coal wall of the small coal pillar,etc.In this paper,the small coal pillar working face of Yangchangwan mine is taken as an example to study the spontaneous combustion characteristics of coal samples,and a special treatment scheme is proposed for the small coal pillar,abandoned roadway and goaf of the working face.?1?Based on the field investigation,geological data investigation and CFD numerical simulation,the risk of spontaneous combustion is analyzed.It is found that there is a large area of primary and secondary thermal damage area in Yangchangwan Coal Mine,small coal pillars are easy to be fractured and form air leakage channel near the goaf,abandoned roadways are affected by ground stress and mining stress,and coal pillars are crushed and form air leakage channel between the air roadways of the current working face,which may cause the goaf and the adjacent goaf to ignite naturally.?2?The spontaneous combustion characteristics of the samples of Yangchangwan2#coal seam were studied by using the coal oxidation kinetics measurement system and gas chromatography.It was found that the samples of Yangchangwan 2#coal seam belong to class I easy to spontaneous combustion coal,and the shortest spontaneous combustion period is 23.36 days.CO,C₂H₄,C₂H₂ are the most obvious gases.As long as C₂H₄ appears,effective fire-fighting measures must be taken.The appearance of C₂H₂ indicates that the local temperature of coal sample exceeds 216.2?.?3?referring to the risk analysis of coal face and the research results of natural law of coal samples,combined with the existing fire prevention and extinguishing system in the working face,a comprehensive fire prevention and extinguishing system based on three-phase foam is designed,combined with grouting,inerting and pressure balancing measures.According to the small coal pillar,abandoned roadway and goaf of the working face,the special treatment schemes are put forward respectively,and good results are achieved.There are 52 figures,23 tables and 71 references in this paper.