Research On Desensitization Mechanism Of Emulsion Explosive Under Dynamic Pressure

Pressure desensitization of emulsion explosives often occur during the millisecond blasting, which behaves as detonation performance decreasing, half explosion or misfire, especially, the phenomenon is more significant with the blast hole span small relatively, underwater blasting and the water trickling working face of mine shaft. It will make subsequent blasting and construction more difficult, make construction period delay, and effect the progress after the desensitization occurs of emulsion explosive, especially, when the misfire occurs, the dealing means is relatively complex in the misfired charge treatment and casualty accidents easily happen. So it is very important to research on the desensitization mechanism of emulsion explosive in order to decrease or avoid the desensitization, ensure normal blasting operation and promote the popularization and application of emulsion explosive.Using underwater explosion test system in this paper, the experimental method was designed to research on the desensitization of emulsion explosive under dynamic pressure. The content and type about sensitization agent and emulsifier were measured; the effects on the desensitization degree of emulsion explosive were discussed. The crystallization quantity of emulsion explosive was measured by water dissolution under dynamic fore-and-aft. And the variation of electrical conductivity was also measured by conductivity method. Microstructure was observed by microscope after emulsion explosive was pressed or not, and the particle size of GMB (glass micro-balloon) was tested by laser particle analyzer. The results of research show that the type and content of sensitization agent have an important effect on desensitization degree of emulsion explosive, the performance of dynamic pressure resistance of GMB is better than that of expanded perlite. So if the sensitization agent content decreases appropriately in the case of ensuring emulsion explosive detonation normally. It can make crystallization quantity of emulsion explosive decrease and make the performance of dynamic pressure resistance increase. The performance of dynamic pressure resistance can be improved if the emulsifier content increases and the performance of pressure resistance will be difference if the type of emulsifier is difference, etc. The desensitization mechanism of emulsion explosive was analyzed and discussed under dynamic pressure based on the experiment in this paper. It is believed that the main reasons on desensitization of emulsion explosive are the destruction of sensitization bubble carriers and variation of microstructure under dynamic pressure. It makes detonation performance decrease that effective bubbles decrease and destruction of interfacial film which caused by bubble carrier breakdown. Destructions of microstructure show that colloidal particles occurs aggregation, demulsification, crystallization, and colloidal particle sizes increase, it makes detonation performance of emulsion explosive decrease, and occur desensitization.