Key Takeaways & Executive Findings
- •• A temperature-responsive composite inhibitor (CaCl2, APP, CaHP) effectively suppresses coal spontaneous combustion across different reaction stages via physical and chemical synergy. • The composite inhibitor increased the ignition point of long-flame coal by 37.15 °C, demonstrating significant thermal stabilization. • Inhibition rates exceeded 20% for gas-phase products and 30% for functional groups, indicating strong suppression of oxidation reactions. • The inhibitor effectively quenches free radicals (H, HO, O), reducing oxidation activity and providing a basis for intelligent fire prevention in coal mines.
Abstract
Temperature is one of the main causes of spontaneous coal combustion. To improve the flame retardant performance, CaCl2, ammonium polyphosphate (APP), and calcium phosphate (CaHP) were compounded to control the temperature response of different stages of coal spontaneous combustion through physical and chemical synergy. Simultaneous thermal analysis, thermogravimetric-Fourier infrared spectroscopy (TG-FTIR), in-situ FTIR and electron paramagnetic resonance (EPR) were used to study the multi-temperature stage synergistic inhibition of coal spontaneous combustion. The results show that the proposed method is effective. By obtaining the characteristics of the spontaneous combustion reaction stage of coal in advance, the method of configuring an appropriate composite inhibitor can effectively realize the intelligent control of the temperature response of coal spontaneous combustion. The ignition point of long-flame coal increased by 37.15 °C. The inhibition rate of the gas phase products was more than 20%, and the inhibition rate of the functional groups was more than 30%. It has a good quenching effect on free radicals and can effectively inhibit the oxidation activity of active free radicals such as H, HO, and O. The results provide experimental and theoretical support for the study of temperature-responsive composite flame retardants for coal with different metamorphic degrees.
1. Introduction
At present, the global energy system is undergoing profound changes guided by the goal of “carbon neutrality” [1,2]. As an important fossil energy source worldwide, coal has historically provided a strong impetus for the development of human society and industry. However, spontaneous combustion during mining, storage, and transportation not only causes huge waste of resources and economic losses, but is also the main cause of mine fires, toxic and harmful gases, and dust explosions, which seriously threaten the safety of mine production and the life and health of personnel [3,4]. Therefore, it is of great practical significance to promote the green and low-carbon transformation of the coal industry by thoroughly exploring the mechanism of coal spontaneous combustion and developing efficient and environmentally friendly new flame-retardant technologies.
Coal spontaneous combustion is an extremely complex physical and chemical process. Its essence is the spontaneous oxidation reaction of coal and oxygen and the accumulation of heat, which eventually leads to the chain combustion reaction [5]. In view of this process, flame retardants can be introduced to interrupt or delay the chain reaction of coal-oxygen composite, so as to achieve the purpose of prevention and treatment [6]. Physical inhibitors suppress coal spontaneous combustion primarily by isolating oxygen or reducing temperature. For instance, chloride-based inhibitors such as CaCl2 and MgCl2 function through moisture retention, hygroscopicity, and creating a barrier between coal and oxygen. Their effectiveness is influenced by factors including the type of inhibitor, concentration, and physicochemical properties [7]. Gao et al. [8] tested the inhibition performance of various inhibitors and found that ...
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Yumo Wu, Dan Zhao, Jinzhang Jia (2025). Study on the mechanism of temperature-responsive composite inhibitors in suppressing coal spontaneous combustion at different reaction stages. SinoTechIntel Verified Research. https://doi.org/10.1016/j.ijmst.2025.12.015
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Frequently Asked Questions
What is the main objective of the study on temperature-responsive composite inhibitors?
The study aims to develop a composite inhibitor (CaCl2, ammonium polyphosphate, and calcium phosphate) that can intelligently suppress coal spontaneous combustion at different reaction stages by responding to temperature changes, thereby improving fire prevention in coal mines.
How does the composite inhibitor work to suppress coal spontaneous combustion?
The inhibitor works through physical and chemical synergy: physical components like CaCl2 isolate oxygen and retain moisture, while chemical components like APP and CaHP react with coal to inhibit oxidation and quench free radicals, thus interrupting the combustion chain reaction.
What were the key experimental results of the study?
The composite inhibitor increased the ignition point of long-flame coal by 37.15 °C, achieved over 20% inhibition of gas-phase products, over 30% inhibition of functional groups, and effectively quenched active free radicals such as H, HO, and O.
What analytical techniques were used in the research?
The researchers used simultaneous thermal analysis, thermogravimetric-Fourier transform infrared spectroscopy (TG-FTIR), in-situ FTIR, and electron paramagnetic resonance (EPR) to study the inhibition mechanisms at multiple temperature stages.
What is the significance of this study for coal mine safety?
The study provides experimental and theoretical support for developing temperature-responsive flame retardants tailored to different coal metamorphic degrees, enabling intelligent control of spontaneous combustion and enhancing safety in coal mining, storage, and transportation.
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