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The frequent occurrence of coal spontaneous combustion (CSC) poses a serious threat to coal mine production safety. Inhibitor fire extinguishing technology has therefore played an important role in reducing CSC in recent years. Microcapsule material is a combined fire extinguishing material that has shown a good effect in preventing CSC. In this study, microcapsule materials were fabricated with short-chain ammonium polyphosphate as the core material and melamine–formaldehyde resin as the capsule material. The microcapsule materials were uniformly mixed with coal samples according to mass ratios of 1:4, 1:5, and 1:6. The quality change of the microcapsule material during heating was detected from thermogravimetric experiments. The results show that microcapsule material decomposition can be divided into five stages. The ammonium polyphosphate begins to decompose at 151.1 °C and the decomposition rate of the microcapsule material reaches a maximum at 200 °C Fourier transform infrared spectroscopy was used to detect the distribution of functional groups during coal oxidation before and after the addition of different microcapsule ratios. The results show that microcapsule materials can reduce the number of hydroxyl and aliphatic hydrocarbons in coal and enhance the stability of aromatic hydrocarbons and oxygenic functional groups. We also performed synchronous thermal analyzer experiments to monitor the temperatures of each characteristic point in the coal oxidation and heating process. The results show that the microcapsule material can reduce the coal mass loss rate, delay the temperature of heat equilibrium by around 100 °C reduce the heat release by more than 4560 J g–1, and increase the maximum temperature of the heat release rate by at least 14 °C. These materials therefore effectively reduce the coal-oxygen composite reaction rate and delay the CSC process.

At present, inhibitors have been widely used in the field of coal fire prevention and control, but there are some defects in the use of them. So it is necessary to find a new practical and economical inhibitor. Dissolvable tiny-foam extinguisher (DTE) is environment-friendly, high in thermal stability, and fast in cooling. In view of the good performance of the product, the thermal behavior effects of DTE on coal spontaneous combustion were investigated through experimental tests. A scanning electron microscopy was used to study changes in the surface microstructure of raw coal after DTE treatment. Laser thermal conductivity analysis and simultaneous thermal analysis were used to test the effects of DTE at mass fraction of 0%, 5%, 10%, and 15% on the thermophysical properties, mass loss, characteristic temperature, and heat release of coal during heating. The surface of the DTE-treated coal sample was covered in a dense film. The treated coal sample had lower thermal diffusivity and thermal conductivity values and a higher specific heat capacity. Moreover, coal treated with DTE showed no obvious oxygen absorption or mass gain during initial heating, and the dry cracking temperature was greatly increased by 37 °C, 53 °C, and 100 °C, respectively. The initial heat release temperature increased by more than 170 °C, and the amount of the initial heat absorption was more than 52.2 times that of untreated samples. Oxidation kinetics were applied to calculate the activation energy of the coal during thermal decomposition and ignition, and the activation energies of the treated samples at the thermal decomposition and combustion stages increased by 161%, 179%, and 173%, respectively. From these results, we concluded that DTE could inhibit heat accumulation by blocking oxygen contact with the coal and greatly reducing heat release during heating. Besides, only a small quantity of DTE was needed to effectively inhibit coal self-ignition. These results provide reference for the field application of DTE in restraining coal spontaneous combustion.

In the process of multi-seam mining, the measure of water exploration is usually employed for the upper coal seam to prevent and control water accumulation. The residual coal immersed in water for a long time in the upper layer is dried under the action of air leakage, leading to the enhancement of the risk of coal spontaneous combustion. Therefore, it is necessary to study the water soaking–drying process (WSD) on the spontaneous ignition characteristics of coal. In this study, a laser thermal conductivity analyzer was used to investigate the changes in thermal properties of bituminous coal collected from mines in western China after WSD. The results show that compared with the raw (unsoaked) coal samples, the thermal diffusivity, specific heat capacity, and thermal conductivity of the bituminous coal are considerably reduced after WSD; the maximum reductions in the three parameters are 11.11%, 6.64%, and 12.39%, respectively. These reduced thermal parameters indicate that after WSD, bituminous coal is more prone to self-heating, resulting in an increase in the rate of coal–oxygen compound reactions and a significantly increased risk of spontaneous combustion.

Proximate and ultimate analysis, X-ray diffraction, infrared spectroscopy and thermal analysis experiments were carried out to study the spontaneous combustion oxidation based characteristic of six Jurassic coal samples from North Shaanxi in West China and three Permo-carboniferous coal samples from East China. The results showed that the characteristic of north Shaanxi Jurassic coal was low ash, low sulfur, high volatile, high oxygen content and amorphous structure. More type and quantity of reactive functional groups existed in the original Jurassic coal, such as carboxyl, methyl, methylene and ether oxygen. And the characteristic temperatures of north Shaanxi Jurassic coal sample in the oxidation and spontaneous combustion process was lower than other coal samples, due to the participation in the reaction with oxygen of the more active functional groups.

The coal fire is one of very serious disasters in natural, not only amount of coal resources was burned and some ecological environment problems such as ground subsidence, acid rain, pollution and vegetation died were caused serious. The No.4 coal seam outcrops fire in Haibaoqing was take as research object, based on the existing theory of mechanism and characteristics of coal outcrop fires, a new fire-fighting composite gel is applicated which fits in with extinguishment of outcrop coal fires well. The technology has many advantages in extinguishing coal fires including isolating the coal from oxygen and lowering the temperature of the high-temperature coal and rock. The structure and chemical composition as well as fires-fighting properties of the composite gel is analyzed profoundly, as a result, reduce and stop the environment destruction caused by the coal fire.

The CO gas in the upper corner along with the work of mining face in different coal-seam of Lingwu coal-field has deeply affected judgment for the degree of the coal spontaneous combustion and safety work. For this issue, a new calculation and forecast model of the carbon monoxide concentration in the upper corner of mining face was deduced for analyzing and calculating the date from the lab and test-in-place, during this course using the knowledge of heat transfer, fluid dynamics, and mathematics. The model took into account the characteristics of the coal spontaneous combustion, coal mining conditions, and other correlate factors, so the CO concentration of the upper corner safe under the normal condition, and it is in danger when the coal reached spontaneous combustion, which can be calculated accurately with the model and compared with the measured concentration with a tolerance of less than 12%.