In order to understand the characteristics of the spray field of a dust suppression nozzle and provide a reference for dust nozzle selection according to dust characteristics, a three-dimensional phase Doppler particle analyzer (PDPA) spray measurement system is used to analyze the droplet size and velocity characteristics in a spray field, particularly the joint particle size–velocity distribution. According to the results, after the ejection of the jet from the nozzle, the droplets initially maintained some velocity; however, the distribution of particles with different sizes was not uniform. As the spray distance increased, the droplet velocity decreased significantly, and the particle size distribution changed very little. As the distance increased further, the large droplets separated into smaller droplets, and their velocity decreased rapidly. The distributions of the particle size and velocity of the droplets then became stable. Based on the particle size-velocity distribution characteristics, the spray structure of pressure-swirl nozzles can be divided into five regions, i.e., the mixing, expansion, stabilization, decay, and rarefied regions. The expansion, stabilization, and decay regions are the effective dust fall areas. In addition, the droplet size in the stabilization region is the most uniform, indicating that this region is the best dust fall region. The conclusions can provide abundant calibration data for spray dust fall nozzles.

At present, the world is committed to the development of environmentally friendly, sustainable and industrial safety. The effective treatment of industrial solid waste can be applied in the field of industrial safety. It is one of the ways to apply industrial solid waste to industrial safety to modify industrial solid waste and combine active powder to prepare industrial solid waste-based composite powder explosion inhibitors and apply it to underground coal dust explosion. This paper introduces the modification and preparation methods of industrial solid waste, and analyzes the good explosion suppression effect and good economic benefit of industrial solid waste-based composite powder explosion inhibitors on coal dust explosion. In this paper, four kinds of industrial solid wastes (red mud, slag, fly ash and sludge) were modified, and the modified solid waste materials with good carrier characteristics were obtained. Combined with a variety of active powders (NaHCO₃, KH₂PO₄ and Al(OH)₃), the industrial solid waste-based composite powder explosion inhibitors were obtained by solvent-crystallization (WCSC) and dry coating by ball milling (DCBM). Those kinds of explosion inhibitors can suppress the explosion of pulverized coal in 40–50% of cases. Compared with the powder explosion inhibitor commonly used in industry, it has a lower production cost and better explosion suppression effect. Those kinds of explosion inhibitors have a good industrial application prospect.

The suppression effect of adding different proportions of NaCl and NaHCO₃ powder on flour explosion was studied by using Hartmann experimental device and 20 L spherical explosive device. The results showed that with the increase of NaCl and NaHCO₃ concentrations, the flame speed and propagation distance decreased gradually. The maximum explosion pressure P_max and the maximum pressure rise rate (dP/dt)_max decreased significantly. When 80% NaCl and NaHCO₃ were added, the average flame propagation velocity reduced to 2.73 m/s and 0.56 m/s, respectively, and the maximum explosion pressure less than 0.15MPa, the flour explosion could be inhibited by NaCl and NaHCO₃. NaHCO₃ was more effective than NaCl in inhibiting flame propagation and explosion overpressure. Finally, combined with the pyrolysis characteristics of NaCl and NaHCO₃, the mechanism of inhibitors inhibiting the explosion of flour was further studied. The endothermic decomposition of NaHCO₃ produced inert gas, diluted oxygen concentration, captured active free radicals, and terminated the combustion chain reaction. NaCl inhibits the explosion of flour by absorbing heat and coating it.

This study investigated the inhibitory effect and mechanism of modified ultrafine ABC powder on the explosion of a methane (CH₄)/coal dust mixed system. Through experiments, it was found that the addition of ABC powder significantly weakened the deflagration characteristics of the CH₄/coal dust mixture system. During decomposition, heat was absorbed to generate ammonia and phosphoric acid. Inert gases such as CO₂ and water vapor produced during decomposition could dilute the oxygen concentration. Phosphate ions produced during the decomposition of ammonium phosphate would bind with free radicals during combustion, reducing their reactivity. The explosion reaction was suppressed through a dual mechanism of physical cooling and chemical consumption of free radicals. The experimental results showed that the weight loss rate of modified ABC powder was 49% at 800 °C, while the weight loss rate of unmodified ABC powder was 78%. The modified ABC powder had better thermal stability and could absorb more heat at high temperatures, further suppressing explosive reactions. This study provides a new modification scheme for explosion suppressants for coal mine safety, which has important theoretical and practical application value.

In order to study the injectability of the advanced inhibiting coal seam and the effect of inhibitor injection, taking the 3 upper coal seam in Nantun mine as an example, on the basis of the fact that this coal seam can be injected, the experiment of pressurized water absorption for coal in 9 different solution of inhibitor was carried out. The minimal aperture of pore that allows inhibitor to be injected is deduced according to the pore distribution. The quality of inhibitor that be injected into the coal is calculated. Research shows that the type and concentration of the inhibitor will have an impact on the injection. MgCl2 at a concentration of 25% is easier to injected into the coal. The minimal aperture of pore that allows MgCl2 to be injected is 0.08μm.Per ton of coal can be injected 3.80 kg of MgCl2. MgCl2 at a concentration of 25% should be given a priority to be used to achieve the advanced inhibition of this coal seam.

A new energy material, a high-energy expansion agent (HEEA), was proposed for the harsh engineering environment of a mine. A safety test and field engineering test were carried out. The results showed that the mechanical sensitivity of the HEEA was extremely low, and no combustion and explosion occurred in multiple impact and friction tests. Meanwhile, the HEEA only burns in open spaces without detonation. Through field experiments, the HEEA can achieve a good blasting effect, providing strong support for its promotion in low-disturbance environmental engineering applications.