Research Status and Development Trend of Materials for Coal Spontaneous Combustion Prevention and Control: A Review

Coal is a core fossil energy resource that has long dominated the primary energy consumption system, serving as a key driver of the global industrialization process and economic growth. During coal mining operations, coal spontaneous combustion occurs frequently, seriously threatening the safety of mine production and causing severe economic, resource, and environmental losses. It remains a persistent engineering challenge that must be addressed. Based on the mechanisms, processes, and influencing factors of CSC, this paper discusses the characteristics, inhibitory mechanisms, and practical effectiveness of three different types of CSC prevention and control materials: physical materials, chemical materials, and physicochemical synergistic materials. This review highlights research on representative cutting–edge materials, such as smart–responsive gels featuring a dynamic sol–gel phase transition mechanism, CO2–adsorbing gels with an adsorption capacity of up to 0.86 cm3/g that reduce CO emission by 25.97% at high temperatures, and natural and biomass–based synergistic inhibitors capable of significantly increasing activation energy and scavenging free radicals. Specifically, the latter includes quercetin solid lipid inhibitors and tea polyphenol nanofoams that reduce CO emission by up to 80.67%, along with a waste lignin system maintaining an ultra–high water retention rate of 185 g/g. In addition, the shortcomings of current research are identified: conventional halogen–containing salts and certain ammonium salts pose severe secondary environmental pollution risks, such as groundwater salinization and mine equipment corrosion. Furthermore, conventional foam materials suffer from extremely short half–lives under extreme thermal conditions, while traditional grouting materials are highly prone to shrinkage and cracking after water loss, subsequently triggering severe secondary air leakage. Meanwhile, the prohibitive costs of advanced chemical inhibitors – such as organic double–network gels, complex modified antioxidants, and specific bio–based materials that are difficult to scale up – make them unfeasible for large–scale application. Future research and trends should primarily pivot toward the large–scale resource utilization of industrial solid waste, artificial intelligence–assisted molecular design of materials, and the development of smart environment–responsive materials capable of in–situ monitoring and automatic fire extinguishing, in order to meet the stringent prevention and control requirements under complex geological conditions.