安全与环境学报

针对当前煤自燃阻化剂普遍存在的阻化效率低、作用时间短、高温易失效且部分产物有毒有害的问题，结合镁基材料环境友好、成本低廉、高温稳定性优异的优势，将氯化镁(MgCl₂)与氢氧化镁[Mg(OH)₂]复配制备镁基复合阻化剂。采用同步热分析、指标气体生成、扫描电镜及原位红外等试验，探究煤样的热效应规律、阻化剂最优参数组合及微观机理。结果表明：阻化效果随阻化剂质量分数和MgCl₂质量占比的增加呈先升后降趋势，硅烷偶联剂质量分数对阻化效果的影响较小；复合阻化剂最优参数组合为阻化剂质量分数30%、Mg(OH)₂/MgCl₂质量比1:2、硅烷偶联剂质量分数1.5%，阻化煤样300 ℃前净放热量较原煤降低130 J/g，吸氧增重与热解阶段活化能较原煤分别提高41.3 kJ/mol、66.9 kJ/mol，且最大阻化率与阻化寿命分别为80%、210 min；阻化煤样分散性显著提升，元素分布更为均匀密集；在低温阶段，MgCl₂通过强吸水性形成液态水膜，既阻隔氧气与煤表面的接触，又为Mg(OH)₂提供均匀分散载体，随温度升高，MgCl₂脱水生成气态水可带走部分氧化热量，Mg(OH)₂热分解生成的高熔点MgO会在煤表面形成连续致密的覆盖层。

In response to prevalent issues such as low inhibition efficiency， short duration of effectiveness， susceptibility to failure at high temperatures， and potential toxicity of by-products associated with current coal spontaneous combustion inhibitors， this study leverages the environmentally friendly， low-cost， and high-temperature stability of magnesium-based materials to develop a composite inhibitor. This inhibitor combines magnesium chloride (MgCl?) and magnesium hydroxide [Mg(OH)?]. A series of experiments—including synchronous thermal analysis， gas measurement， scanning electron microscopy， and in-situ Fourier transform infrared spectroscopy—were conducted to investigate the thermal behavior of coal samples， determine the optimal parameter combination for the inhibitor， and elucidate the underlying microscopic mechanisms. The results indicate that both the mass fraction of the inhibitor and the mass ratio of MgCl? exert a nonlinear influence on inhibition performance， initially enhancing it before leading to a decline. In contrast， the mass fraction of the silane coupling agent has a relatively minor effect. The optimal parameters for the composite inhibitor were identified as: an inhibitor mass fraction of 30%， an Mg(OH)?/MgCl? mass ratio of 1:2， and a silane coupling agent mass fraction of 1.5%. Under these conditions， the net heat release of the inhibited coal sample below 300 °C was reduced by 130 J/g compared to raw coal. The activation energy during the oxygen-absorption weight-gain stage and the pyrolysis stage increased by 41.3 kJ/mol and 66.9 kJ/mol， respectively. Moreover， the maximum inhibition rate reached 80%， with an inhibition lifetime extending to 210 minutes. SEM observations revealed significantly improved dispersion and a more uniform， dense distribution of elements on the surface of the inhibited coal sample. Mechanistically， during the low-temperature stage， MgCl? forms a liquid water film due to its strong hygroscopicity， which not only isolates oxygen from the coal surface but also acts as a uniform dispersion medium for Mg(OH)?. As the temperature rises， the dehydration of MgCl? produces gaseous water， thereby dissipating some oxidation heat. Concurrently， the thermal decomposition of Mg(OH)? yields high-melting-point MgO， forming a continuous， dense coating over the coal surface that provides sustained barrier protection at elevated temperatures.