Experimental Evaluation of Agricultural Ammonium Nitrate as an Explosive in Underground Artisanal Mining

The use of agricultural-grade ammonium nitrate without fuel oil as an explosive has been empirically observed in underground artisanal mining in Ecuador. Despite its practical adoption, the explosive behaviour of this material has not been adequately characterized through experimental measurements. This study presents an experimental evaluation of agricultural ammonium nitrate used as an explosive in underground artisanal mining, with velocity of detonation (VOD) employed as the main control variable. Field-scale experiments were conducted under confined conditions and through in situ measurements in underground production tunnels, using configurations involving ammonium nitrate and commercial emulsion explosives. VOD measurements were performed using a high-sensitivity recording system suitable for short charge lengths. The results show that the emulsion explosive detonated reliably, whereas detonation transferred to the ammonium nitrate column rapidly weakened and collapsed. Detonation propagation within the ammonium nitrate was limited to short distances or extinguished entirely, indicating a non-ideal detonation regime in which sustained propagation cannot be maintained under underground artisanal mining conditions. The study provides rare field-scale data on the physical limits of detonation in low-sensitivity energetic materials, obtained under realistic underground artisanal mining conditions.