| Emulsion explosive is an industrial explosive with water-in-oil(W/O). Because of its good explosion performance, low mechanical sensitivity and proper fluidity, emulsion explosive is now widely used in industrial production and engineering blasting, but the storage stability of site-mixed emulsion explosives is still poor. To improve the stability of site-mixed emulsion explosives used by Dexing Copper Mine and meet the needs of blasting with pre-loaded explosives for 3 days, the storage stability and explosive performance of the emulsion explosives with a single emulsifier and compound emulsifiers has been studied and analyzed in this paper, while effects of emulsifier, p H value in aqueous phase and the amount of foaming agent on density and detonation velocity of emulsion explosives have been analyzed. Then the pre-blasting performance and economic benefit of emulsion explosives before and after the improvement were evaluated. The best emulsifier formulation and preparation techniques of emulsion explosives with good stability and detonation velocity which meets the demand of industry were obtained.First, automatic rheometer was used to study the viscosity-temperature characteristics,visco-elasticity and yield stress of emulsion matrixes made of Span-80, polymer emulsifier and compound emulsifier. The results show that the viscosity, yield value and cohesion of emulsion matrixes made of polymer emulsifier is all higher than that of Span-80; increasing the proportion of LZ27011 can enhance vibration resistance of emulsion matrixes.Meanwhile, the surface tension of LZ polymer emulsifiers is all greater than that of Span-80. The high and low temperature cycle test and natural storage test also indicate that the stability of emulsion matrixes containing LZ emulsifier is much better than that of single Span-80. In conclusion, considering the stability, explosive performance and economic benefits of blasting with pre-loaded explosives, the compound emulsifier LZ27011/Span-80(30/70) is chosen as a preferred emulsifier formulation.Secondly, effects of p H value in aqueous phase and the amount of foaming agent on density and detonation velocity of emulsion explosives were studied in the laboratory. Then detonation velocity was measured under different storage time. The research shows that p H value in aqueous phase suitable for LZ27011/Span-80(30/70) is 3.5~3.8; The required optimum amount of foaming agent for 1 kg emulsion matrixes is 1.0 m L~1.5 m L. Thus, the explosive density was 1160 kg m-3~1230 kg m-3 while the range of detonation velocity was3921 m s-1~4901 m s-1.Finally, hole-packing, storage and blasting of emulsion explosives produced by site-mixed cars were conducted in the open-air copper mine. The results show that the initiation reliability and blasting performance were very good. Meanwhile, the conclusion that p H value in aqueous phase(3.5~3.8) is suitable for LZ27011/Span-80(30/70) was further validated, and with the foaming agent flowmeter 30 L/h~40 L/h on site-mixed cars,the explosive density could be controlled in 1180 kg m-3~1230 kg m-3. Since the average detonation velocity of pre-loaded explosives for 3 days is 4397 m s-1and the economic benefits it will bring is significant, the compound emulsifier LZ27011/Span-80(30/70) can meet the needs of blasting with pre-loaded explosives to be used in Dexing Copper Mine. |
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