液态二氧化碳是目前矿井煤自燃火灾治理常用的降温惰化材料，在快速处理煤自燃火灾方面被实践验证具有灭火速度快、惰化效果好的优势。因矿井条件各异、现场条件复杂多变，在针对复杂采空区煤自燃问题时，通常采用多种防灭火技术综合应用的方式进行治理。为进一步提高液态二氧化碳防灭火技术的使用效果和适用范围，本文从松散煤体渗透性和吸附性两个影响液态二氧化碳降温惰化效果的因素出发，研究高温松散煤体液态二氧化碳-水复合作用后的降温惰化效果，并通过现场应用进行验证。

       通过松散煤体注水渗流实验发现，水力侵蚀作用可以改变松散堆积煤体的粒径分布，增加煤体局部区域的堆积孔隙率和渗透率，从而提高松散煤体局部区域对于流体的渗透性；通过液氮吸附实验和二氧化碳吸附实验发现，水力侵蚀作用可增大煤体基质孔隙的孔容和孔径，从而提高煤体对二氧化碳的吸附性。

       通过高温松散煤体降温实验发现，高温火区注水降温范围仅限于水的渗流路径，且会将热量通过水流转移产生新的高温区域，停止注水后已降温区域受热蒸汽的影响温度会再次回升；注液态二氧化碳降温效果明显优于注水降温，降温后的最低温度可达-70℃以下，降温范围较大，降温后的低温状态维持较长时间；液态二氧化碳-水复合作用降温的降温温度更低、降温范围更广、降温后低温状态的维持时间更长；通过对降温实验煤样进行低温氧化实验发现，相比单一液态二氧化碳降温，液态二氧化碳-水复合降温后的煤样在低温氧化阶段受到的抑制作用更明显，体现出更好的惰化效果。

       利用液态二氧化碳-水复合作用方式，对某矿2201工作面回风巷外侧2^-2煤房柱式采空区进行降温惰化。通过钻孔监测的方式对该采空区内气体浓度、温度进行长期全面的观测，发现二氧化碳在采空区内进行了大范围的扩散覆盖。在后续生产过程中，2^-2煤房柱式采空区长期保持高二氧化碳、低氧、低温状态，有效预防了煤自燃火灾的发生，验证了液态二氧化碳-水复合作用的降温惰化效果。

       Liquid carbon dioxide is a commonly used cooling and inerting material for coal spontaneous combustion fire management. It has the advantages of fast extinguishing speed and good inerting effect in the rapid treatment of coal spontaneous combustion fires. The spontaneous combustion of coal in the goaf is complicated and changeable due to the different mine conditions, and it is usually controlled by the comprehensive application of a variety of fire-fighting technologies. In order to improve the use effect and scope of application of the liquid carbon dioxide fire-fighting technology, this paper is based on the study of the two factors that affect the porosity and permeability of the loose coal, through experiments and applications to study the cooling and inerting effect of LCO₂-H₂O in high-temperature loose coal.

       Through water injection seepage experiments of loose coals, it is found that hydraulic erosion can change the particle size distribution of loose coals, increase the porosity and permeability of local areas of coals, and improve the permeability of local areas of loose coals to fluids; Through liquid nitrogen adsorption experiments and carbon dioxide adsorption experiments, it is found that hydraulic erosion can increase the pore volume and pore size of the coal matrix pores, thereby improving the coal's adsorption of carbon dioxide.

       Through the cooling experiment of high-temperature loose coal, it is found that water injection and cooling in high-temperature fire area will transfer heat through the water flow to generate a new high-temperature area. After the water injection is stopped, the temperature of the cooled area will rise again under the influence of the heated steam; Liquid carbon dioxide injection is obviously better than water injection for cooling . The lowest temperature after cooling can reach -70℃ or less, and the cooling range is larger, and the low temperature state after cooling will be maintained for a longer time; The cooling temperature of the LCO₂-H₂O compound action method cooling is lower, the cooling range is wider, and the low temperature state after cooling is maintained for a longer time; Through the low-temperature oxidation experiment of the coal sample in the cooling experiment, it is found that compared with the cooling of a single LCO₂ action method, the coal sample after the cooling of the LCO₂-H₂O compound action method is more inhibited in the low-temperature oxidation stage, showing a better inerting effect.

       Using the LCO₂-H₂O compound action method, the room and pillar goaf in the 2^-2 coal seam outside the return air tunnel of the 2201 working face of the coal mine is cooled and inerted. Long-term comprehensive observations of gas concentration and temperature in the goaf were carried out through borehole monitoring, and it was found that carbon dioxide had spread and covered a large area in the goaf. In the subsequent production process, the room and pillar goaf of the 2^-2 coal seam maintains high carbon dioxide, low oxygen, and low temperature conditions for a long time, effectively preventing the occurrence of coal spontaneous combustion, and the cooling and inerting effect of the combined action of water and liquid carbon dioxide was verified.

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