Abstract
A potentially dangerous explosion was triggered by the inadvertent mixing, at ambient temperature, of small quantities of nitric acid and an unidentified organic substance.
The explosion occurred in a knock-out vessel at a hazardous waste treatment centre. Two operators were injured and the vessel was severely damaged, with the side wall parting from the base. Other tanks, pipe work and connections also suffered serious damage.
Based on the documented waste streams present, and the apparent lack of mixing of incompatible streams, the incident was at first difficult to explain. However, laboratory analysis of residues from the knock-out vessel confirmed the presence of traces of an organic nitro compound, providing the final link in the chain of a plausible mechanism for the explosion.
The incident underlines the importance of strict separation of nitric acid and organics in the treatment of hazardous wastes.
