煤自燃火灾是煤炭开采、储存、运输过程中的主要灾害之一，不仅浪费煤炭资源，产生大量的有毒有害气体，还严重危及井下人员的生命安全，因此实现煤自燃火灾的科学防控一直是煤炭资源安全高效开采的重要课题。基于采空区、老巷道、封闭区内隐蔽高温区域难以精准探测的现实问题，采用压注惰性气体进行大面积降氧控漏成为大部分矿井日常防火的主要手段。二氧化碳（CO2）和氮气（N2）作为典型的惰性气体被广泛应用，但 N2存在防灭火效果差、易逸散、能耗大等不足，而 CO2存在运输困难、易堵塞管路、工艺复杂、成本高等缺点，如何扬长避短，科学利用 CO2/N2惰化防灭火技术，对实现煤自燃隐患科学防控具有重要现实意义。本文围绕单一注 CO2/N2 和不同比例的 CO2-N2混合气体对煤自燃惰化性能进行了实验和模拟对比性研究，为进一步提升煤矿惰性气体防灭火技术应用效果提供理论基础和数据支撑，结果表明：
（1）采用吸附特性实验，对单一 CO2/N2和不同比例 CO2-N2混合气体的吸附特性进行了研究，综合分析混合气体浓度比、煤变质程度和温度对吸附特性的影响。基于多因素方差分析法，定量地分析各影响因素下吸附性能的差异性，得到：相同条件下， 4 种混合惰气中 30%N2+70%CO2 对煤的吸附性能最佳，与 100%CO2 无显著差异；高变质程度的无烟煤的吸附性能优于烟煤和褐煤；吸附性能随温度的升高而降低。
（2）采用程序升温实验，对比研究了注单一 CO2/N2和不同比例 CO2-N2混合气体对自燃煤体降温过程特征参数的变化规律，得到：相同条件下，向临界温度（70℃）的煤体压注惰气过程中，30%N2+70%CO2对高温煤体自燃氧化的抑制效果优于 CO2、N2及其他比例惰气；向干裂温度（120℃）的煤体压注惰气过程30%N2+70%CO2的降温、降氧效果优于 CO2、N2及其他比例惰气，但 10%N2+90%CO2的 CO 浓度变化更显著。
（3）从注气口位置、压注流量和不同比例 CO2-N2混合气体三个角度对比注惰后采空区氧浓度和氧化带分布的惰化效果，确定了合理的注气口位置及压注流量，并得到：不同比例的 CO2-N2 混合气体对采空区煤自燃的惰化效果的差异性并不明显，30%N2+70%CO2对采空区氧化带的惰化效果略优于其他比例混合气体。

  Coal spontaneous combustion fire is one of the main disasters in the process of coal mining, storage and transportation. It not only wastes coal resources, produces a large amount of toxic and harmful gases, but also seriously endangers the life safety of underground personnel. Therefore, the scientific prevention and control of coal spontaneous combustion fires has always been an important topic in the safe and efficient mining of coal resources. Based on the fact that it is difficult to accurately detect the hidden high-temperature areas in goafs, old roadways, and enclosed areas, the use of pressure injection of inert gas to reduce oxygen in large areas and control leakage has become the main method for daily fire prevention in most mines. CO2 and N2 are widely used as typical inert gases, but N2 has disadvantages such as poor fire-fighting effect, easy dissipation, and high energy consumption. However, CO2 has the disadvantages of difficult transportation, clogging of pipelines, complicated process and high cost. How to develop strengths and avoid weaknesses and scientifically utilize CO2/N2 inerting fire-fighting technology is of great practical significance for the scientific prevention and control of coal spontaneous combustion hazards. In this paper, a series of experiments and simulation comparative studies on coal spontaneous combustion inerting performance are carried out around a single CO2/N2 injection and different proportions of CO2-N2 mixed gas, which provide theoretical basis and data support for further improving the application effect of coal mine inert gas fire-fighting technology. The result is as follows:
  The adsorption characteristics of CO2-N2 mixed gas under single CO2/N2 and different concentration ratios were studied by using adsorption characteristic experiments. Based on multi-factor analysis of variance, the difference of adsorption performance under each influencing factor was quantitatively analyzed, and it was obtained: under the same conditions, the adsorption performance of 30%N2+70%CO2 in four kinds of mixed inert gas to coal was the best, which was the same as that of 100%CO2. The adsorption performance of high metamorphic anthracite coal is better than that of bituminous coal and lignite; the adsorption performance decreases with the increase of temperature.
  The temperature-programmed experiment was used to compare and study the variation law of the characteristic parameters of the spontaneous combustion coal body by injecting a single CO2/N2 gas and different proportions of CO2-N2 mixed gas. In the process of inert gas, 30%N2+70%CO2 has a better inhibitory effect on the spontaneous combustion and oxidation of high temperature coal than CO2, N2 and other proportions of inert gas; in the process of pressure injection of inert gas into the coal body with a dry cracking temperature of 120℃, 30%N2+70%CO2 has better cooling and deoxidizing effects than CO2, N2 and other proportions of inert gas, but the CO concentration of 10%N2+90%CO2changes more significantly.
  Comparing the inerting effect of the oxygen concentration and the width of the oxidation zone in the goaf from the position of the gas injection port, the pressure injection flow rate and the CO2-N2 mixed gas in different proportions, the reasonable position of the gas injection port and the pressure injection flow rate were determined, and obtained: The difference between the inerting effect of CO2-N2 mixed gas on spontaneous combustion of coal in goaf is not obvious, and the inerting effect of 30%N2+70%CO2 on the oxidation zone of goaf is slightly better than other proportions of mixed inert gas .