Two miners have received serious and minor injuries from a pre-detonated explosion which occurred during an operation where a man-lift was used to charge blast holes – according to an alert issued by the Mine Safety and Health Administration (MSHA). A non-electric shock-tube became wedged on the man-lift basket which stretched and broke causing the incident.
The miners were using non-electric blasting caps, eight grain boosters and ammonium nitrate fuel oil as a blasting agent during the operation.
MSHA has issued best practice guidelines following the accident.
- Explosive materials should be kept organized and under the direct observation of the blaster during loading operations so personnel and equipment does not inadvertently come in contact with them.
- The manufacturer’s recommendations regarding maximum loading on the tubing are to be followed (e.g. maximum primer weight lowered into hole by the tubing).
- Shock tubing is not to be subjected to undue tension by pulling, in hole to hole situations.
- Situations in which shock tubing is subjected to impact by falling rock, equipment etc. is to be avoided.
- Excess shock tubing can be coiled, but should not be cut off.
- Shock l tube downlines should be tied to pegs visible to vehicle operators.
- The blast crew should carefully consider the blast design and plan the loading sequence to avoid having to move over or too near to loaded holes.