Perspectives in the stability of emulsion explosive

Abstract

This review explores the stability of emulsion explosive, through summarizing its instability reason, stability mechanism, affecting factors, improvement ways and evaluation methods. The emulsion explosive can be recognized as highly concentrated emulsion due to the volume fraction of dispersed phase exceed 74%. The polydispersity, deformation of compassed droplets and the high content of AN in dispersed phase should be considered for the stability of emulsion explosive. The coalescence is one of the important factor for the instability of emulsion explosive as the droplets bound to each other tightly, together with that, the crystallization of AN in dispersed droplets will occur. This process will further decrease the stability of emulsion explosive. Interfacial tension, the strength of interfacial film and electrical properties of droplets are the important mechanism for preparation and stability of emulsion explosive, among the three, the effect of the strength of interfacial film is most important, and the greater the strength of the interfacial film, the more stable the emulsion explosive. The stability of emulsion explosive will be affected by the emulsifier's structure, the viscosity and polarity of oil, the crystallization point of AN and the nature of matrix, in which, it is important to pay attention to the influence of emulsifier structure because adjusting emulsifier structure is a key channel to improve the stability of emulsion explosive. Besides that, the targeted methods to improve the stability of different emulsion explosive, such as bulk emulsion explosive, packaged emulsion explosive and powdery emulsion explosive, were concluded and established. Finally, we proposed some effective methods for evaluating and predicting stability of emulsion explosive. These results will facilitate the further development of the researches in the mechanism and improvement approach of stability, as well as it will also provide effective technical support for exploring the stability of other similar highly concentrated emulsions.

Keywords: Emulsifier; Emulsion explosive; Emulsion explosive matrix; Microstructure; Stability.