Nitromethane-assisted reduction of hazardous post-blast gaseous emissions in ANFO under preserved detonation performance

Abstract Reduction of hazardous post-blast gaseous emissions while maintaining blasting performance remains a major challenge in surface mining operations employing ammonium nitrate fuel oil (ANFO). In this study, partial substitution of ammonium nitrate(V) and fuel oil with nitromethane (NM) was investigated as a strategy to simultaneously reduce hazardous fumes and improve detonation performance. Theoretical detonation parameters were calculated using Explo5 software and validated experimentally through velocity of detonation (VOD) and post-blast fume measurements. Incorporation of NM (4–9 wt%) significantly reduced hazardous gaseous emissions, decreasing total CO x and NO x volumes by approximately 43–44% relative to conventional ANFO. Simultaneously, the average VOD increased from 1595 m s⁻¹ for reference ANFO to 2604 m s⁻¹ for the formulation containing 9 wt% NM, demonstrating enhanced detonation propagation under non-ideal conditions. The substantial discrepancy between equilibrium VOD predictions and experimental values reflects the strongly non-ideal detonation behaviour of the investigated formulations and highlights the limitations of equilibrium thermodynamic calculations for predicting their actual detonation performance. The combined experimental results demonstrate that NM incorporation can simultaneously reduce hazardous post-blast gaseous emissions and enhance detonation propagation within the investigated composition range. These findings identify controlled NM incorporation as a promising strategy for reducing the environmental impact of ANFO-based blasting while improving its detonation performance.