| Gas explosion is one of the significant disaster accidents of coal mine, being strongly destructive and sudden. Preventing and controlling gas explosion accident is the key of achieving the safety production of coal mine. How to effectively limit the explosion scope and the possible damage at the lowest degree,which has been a concerning focus for the security workers. The technology of powder explosion suppression can prevent or suppress explosion disaster, that is one of the important issues.This article described the development and the application of the technology of powder explosion suppression in China and abroad , discussed the suppression mechanism of Al(OH)3 and Mg(OH)2 carried out the explosion suppression experiment using the Al(OH)3 and Mg(OH)2 power on the trial system of 20 L spherical stainless explosion container, studied the explosion suppression performance and the explosion suppression parameters about these two ultrafine inorganic powers, meanwhile, qualitatively and quantitatively analyzed the relationship between the ignition delay time, the concentration of powder, the grain size of powder and the explosion characteristics parameters, got the measure of the explosion suppression law of ultrafine powders.The experimental results show that under the condition of Al(OH)3 powder, the time from collecting pressure to arriving the maximum explosion pressure is longer than Mg(OH)2 powder, and the impact on the explosive limits is greater than Mg(OH)2 powder. These phenomena suggest that the explosion suppression effect of ultrafine Al(OH)3 powder is better than the effect of ultrafine Mg(OH)2 powder. The 1.3μm average particle size of Al(OH)3 powder suppresses methane explosion, which can drop the average maximum explosion pressure by 11.08 %, drop the average rise speed of maximum pressure by 66.15 %, drop the average time by 57.53 % that from collecting pressure to arriving the maximum explosion pressure. With ultrafine inorganic metal hydroxide powder increases, both the maximum explosion pressure and the average rise speed of maximum pressure first decrease then increase, that is, existing the best ignition delay time and the best concentration of powder. The same order of powers whose particle size being less different suppresses the explosion of gas with the same concentration, the difference of the best concentration of powder is very little. When the particle size of the inorganic metal hydroxide powder is about 1μm, the best concentration of powder is about 250 g/m3 for 9.5 % methane explosion, while the best concentration of powder is about 200 g/m3 for 7.0 % methane explosion. If the powder particle size is smaller, the scope of the explosion limits is greater, and with the concentration of power increasing, the scope of the explosion limits first decrease then increase, the upper limit will not joint with the lower limit.This paper's conclusions and data can provide the theory basis for the explosion suppression of ultrafine inorganic metal hydroxide powder, and the experiment conclusions have certain guiding sense for ultrafine powder suppressing gas explosion.
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