In an effort to effectively control coal dust pollution and thereby reduce the harm of coal dust to human health, we prepared a highly efficient composite dust suppressant. First, dynamic contact angle and zeta potential measurements were used to select sodium dodecyl sulfonate (SDS) over sodium carboxymethyl cellulose and trisodium methyl silicon as the complementary additive to soy protein isolate for the dust suppressant. We employed viscosity and wind erosion resistance tests to compare the performance of the composite dust suppressant with three common, commercially available suppressants. As the concentration of the composite dust suppressant was increased, the viscosity increased, reaching a maximum value of 22.7 mPa·s at a concentration of 5 wt%. The 5 wt% concentration of the composite dust suppressant provided the lowest wind erosion rate (20.62%) at a wind speed of 12 m/s. The composite dust suppressant also had good bonding performance and wind erosion resistance. Scanning electron microscopy, X-ray diffraction, and thermogravimetric analysis were used to characterize the properties of the dust suppressants. The dust suppressant, which had a crystal-like structure, could easily capture coal dust and form an effective package. In addition, the density of the dust suppressant film increased as its crystallinity increased. The increased density was beneficial in that it enabled the dust suppressant to form a hard, solidified shell on the surface of coal dust, which improved dust suppression. The composite dust suppressant also had good thermal stability.

It is an important measure to inject inhibitor into coal to prevent coal spontaneous combustion (CSC) disasters. At present, it is still a topic worth discussing about the factors affecting the preventing effect of inhibitors on CSC. For this topic, MgCl₂, CaCl₂ and NH₄H₂PO₄ were firstly selected as inhibitors in this paper to carry out the experiment of pre-injection of inhibitors in coal samples and obtain the coal samples injected with inhibitors. Four factors (injection pressure, injection time, concentration of inhibitor, type of inhibitor) affecting the results of inhibition were analyzed by orthogonal statistical method (OSM). After that, the temperature rise experiment was carried out for the raw coal sample and the coal sample injected with inhibitor. The results showed that: when the concentration of the inhibitor was 25%, the injection pressure was 4MPa and the injection time was 2d, a better pre-injection effect could be achieved. The inhibition rate of coal samples injected with NH₄H₂PO₄ was 25.7%, which was higher than that of MgCl₂ and CaCl₂. Therefore, the inhibitor of NH₄H₂PO₄ injected into coal samples can achieve relatively good inhibition effect. The above contents hope to provide a certain basis for the prevention and control of coal-mine fire.

Understanding the regulatory mechanism of oxidation temperature on the secondary spontaneous combustion activity of coal is crucial for establishing spontaneous combustion warning thresholds. FTIR was employed to study the effect of oxidation temperature on coal functional groups. A programmed-temperature experiment was conducted to analyze changes in gas types and concentrations during the secondary spontaneous combustion of oxidized coal. The results indicate that initial oxidation activates functional groups in coal, such as C–O–C, CO, and –CH₃. Therefore, during secondary spontaneous combustion of oxidized coal, as the temperature increases, these functional groups further oxidize and decompose to form gas products. When the oxidation temperature reaches 80 °C, the initial temperature at which coal produces CO and C₂H₄ during the secondary spontaneous combustion process is 40 °C earlier than that of raw coal, and the initial generation concentrations are 42.45% and 28.83% of raw coal, respectively. Therefore, CO and C₂H₄ can serve as indicator gases for predicting the spontaneous combustion of oxidized coal. This work provides valuable insights into the spontaneous combustion process of oxidized coal in shallow buried coal seams.

The moisture content and temperature of coal has a significant impact on the efficacy of inert gases (CO2/N2) in inhibiting coal spontaneous combustion (CSC). Therefore, this study explores the changes in microporous structure, adsorption capacity, heat of adsorption as well as energy distribution and diffusion of CO2/N2 at varying moisture contents (1%–5%) and temperatures (303–343 K). The results demonstrate that water molecules gradually transform large pores in the microporous structure into multiple smaller pores, thus reducing the volume proportion of free pores. The adsorption of CO2/N2 is constrained by the pre-adsorbed water molecules occupying the adsorption sites. Both temperature and moisture exert similar effects on gas adsorption capacity, with higher levels of both reducing the adsorption capacity. Notably, temperature rise is associated with an increased heat of adsorption for the gas molecules. Under moisture effects, there is an observable positive relationship between the gas diffusion coefficient and the adsorption capacity. Conversely, there is a negative correlation with temperature. At low moisture content, CO2/N2 injection is enhanced. High temperatures reduce the effectiveness of CO2/N2 in preventing CSC, while heat can only be exchanged by diluting the oxygen concentration. These results provide crucial insights into the adsorption behavior of CO2/N2 at different temperatures and moisture contents.