Blast crew affected by vapours from acetic acid spillSignificant incident report no. 36 | 15 February 2001 | Version 1
Coal mine – surface
On entering a coal shot to commence loading (emulsion), a contractors explosives manufacturing unit broke a front left hand suspension spring. Consequently the feed line from a tank containing a 45% solution of acetic acid (N17) was damaged and an estimated 20L of acid spilled beneath the truck.
Two of the blast crew, who were in the immediate vicinity, were affected by the colourless vapour, falling to their knees with breathing difficulties. They managed to move away from the truck and accessed fresh air and shouted to the third crew member who in turn alerted the truck operator. The truck operator moved the truck forward at which point the acid leak was observed by the third crew member from some 2m away.
The truck was stopped, the operator isolated the tank and the area was cleared.
Mobile explosives manufacturing unit and N17 emulsion gassing/sensitising agent
N17 is a chemical containing acetic acid in a concentration of less than 50% (household vinegar contains 4 to 8%). N17 is corrosive and toxic and its vapours may cause severe internal/external burns if contacted, ingested or inhaled.
Spillage of acetic acid due to damage to the dispenser system
Comments and recommendations
The Australian code of dangerous goods assigns a Hazchem code of 2R (R indicating no risk of violent reaction or explosion):
Toxic fumes are emitted upon decomposition from heating.
There is potential for a violent eruption due to pressure build-up if heated in an enclosed container. Hence these should be kept cool.
When spilled the main component of the vapour is water which, it is considered, renders the fumes nonexplosive.
Currently there are at least 7 Bowen Basin coal mines using the product.
The following issues need to be reviewed by mine operators, contractors and suppliers generally:
- The road worthiness of all trucks, including those not owned by the mine, operating on the mine site.
- The adequacy of design of systems handling hazardous substances, for example, prevention of damage and spills etc.
- The adequacy of knowledge of operators about the substances under their control and of the appropriate emergency response should control be lost.
- The provision of an emergency kit on the vehicle that would include the appropriate first aid and personal protective equipment required to safely deal with any mishap.
- The accuracy of chemical safety data sheets. (These were inaccurate with respect to particular solution concentrations.)
- The adequacy of the mines hazardous substances management system.
- The adequacy of the mines emergency response procedures with respect to hazardous substances.
Authorised by Peter Minahan - Chief Inspector of Mines
Issued by the Queensland Department of Natural Resources and Mines