Research on the critical temperature of thermal decomposition for large cartridge emulsion explosives

•DSC and ARC were selected for the preliminary investigation of the thermal stability of emulsion explosives.•The slow cook-off experiments were carried out to investigate the Tc of the large cartridge emulsion explosives.•For the large cartridge emulsion explosives with diameter of 70 mm, the Tc was 170 °C.•The Tc obtained in slow cook-off experiments were generally lower than the Tonset obtained from DSC and ARC.•The slow cook-off experiment is more suitable for the thermal safety research of large cartridge emulsion explosives.

Emulsion explosives are one type of main industrial explosives. The emergence of the large cartridge emulsion explosives has brought new security incidents. The differential scanning calorimeter (DSC) and the accelerating rate calorimeter (ARC) were selected for the preliminary investigation of the thermal stability of emulsion explosives. The results showed that the initial thermal decomposition temperatures were in the range of 232–239 °C in nitrogen atmosphere (220–232 °C in oxygen atmosphere) in DSC measurements and 216 °C in ARC measurements. The slow cook-off experiments were carried out to investigate the critical temperature of the thermal decomposition (Tc) of the large cartridge emulsion explosives. The results indicated that the larger the diameter of the emulsion explosives, the smaller the Tc is. For the large cartridge emulsion explosives with diameter of 70 mm, the Tc was 170 °C at the heating rate of 3 °C h−1. It is a dangerous temperature for the production of the large cartridge emulsion explosives and it should cause our attention.