Preparation and performance of novel APP/NaY–Fe suppressant for coal dust explosion

Research on the Inhibition Effect of NaCl on the Explosion of Mg-Al Alloy Powder

A study was conducted on the explosion overpressure and flame propagation law of magnesium-aluminum (Mg-Al) alloy powder, and the suppression mechanism of sodium chloride (NaCl) on the explosion of magnesium-aluminum alloy powder was explored. Adding NaCl powder can effectively reduce the explosion pressure, flame front position, and flame propagation speed. The higher the amount of NaCl powder added, the lower the explosion pressure of magnesium-aluminum alloy powder, the slower the flame propagation speed, and the lower the flame brightness. NaCl adsorbed on Mg-Al alloy powder isolated heat transfer and played a cooling role. The Cl- produced by NaCl decomposition will react with the free radicals H+ and OH- in the reaction system, which will reduce the concentration of H+ and OH- in the combustion process and hinder the propagation and expansion of the flame. The research results provide theoretical guidance for the explosion prevention of Mg-Al alloy powder and the preparation of a physical-chemical compound explosion suppressor in the later stage.

Blasting dust diffuse characteristics of spiral tunnel and dust distribution model: similar experiment and numerical modeling

The special linear shape of spiral tunnel changes the air flow structure during tunnel construction and changes the diffuse and distribution of blasting dust. Mastering the blasting dust distribution and diffuse mechanisms can provide theoretical basis for ventilation layout and dust removal measures during spiral tunnel construction. To study the influence of spiral shape on dust diffusion and concentration distribution after tunnel blasting, a similar scale model of 1:20 and full-scale numerical model of spiral tunnel during construction were established. The similarity criterion and the similarity ratio of each physical quantity are derived from the dust motion equation. The dust distribution and diffuse characteristics in the spiral tunnel under different dust release quantity and release velocity were studied by model experiment. The dust distribution and diffuse characteristics in spiral tunnel with different curvature radius were studied by numerical simulation. The dust distribution model is refined based on the research results. The dust distribution model divides the tunnel into heavily polluted area and slightly polluted area, and the influence characteristics of the curvature radius on the dust export area are found. The layout of ventilation systems can be optimized according to the volume of heavily polluted areas. The heavily polluted area should be as small as possible; the dust in the heavily polluted area should be discharged to the slightly polluted area in an orderly manner to avoid the accumulation of dust. Dust removal measures can also be arranged according to the dust export location to improve dust removal efficiency.

The Performance and Mechanism of the Green Explosion Suppressant SGA for Coal Dust Explosion Suppression

In recent years, coal processing is developing rapidly, but there are often hidden safety hazards such as coal dust explosions during coal processing. In order to ensure safe production and avoid coal dust explosion accidents, a carrier with unique micro-mesoporous structure (SG) based waste molecular sieves was prepared. After that, the carrier was loaded with (NH4)2C2O4(A) uniformly by ultrasound, which acted as an activity component for the first time. A novel micro-mesoporous coal dust explosion suppressant (SGA) is obtained. The law influence of different compositions of suppressant on the flame propagation of explosion was investigated. The results showed that the best ratio of waste molecular sieve, zirconium dioxide, and (NH4)2C2O4 of the suppressant is 1:7:2. The suppression performance increases with the increase of the addition of suppressant. When the addition amount is 70 wt %, the explosion loses the ability to continue to expand. Finally, combining the suppression performance with characterization results, the physical and chemical synergistic suppression mechanism is proposed, which reveals the reason why the suppressant has efficient suppression performance. The study could realize the green reuse of waste molecular sieves and provide guarantees for safe production of the coal processing industry.