Serious Accident Alert: Two miners injured in pre-detonation blast

Kerry Clines

April 10, 2018

The Mine Safety and Health Administration (MSHA) issued a Serious Accident Alert after two miners were injured in an explosion. On March 24, 2018, two miners at a Fred Weber underground quarry in Missouri were using a man-lift to charge (load) blast holes with non-electric blasting caps, 8-grain boosters, and ammonium nitrate fuel oil (ANFO) blasting agent. During the loading process, one of the non-electric shock-tubes became wedged on the man-lift basket. As the man-lift operator progressed across the face loading the blast holes, the wedged-shock tube stretched and broke (snapped), causing a pre-detonation of a blast hole. As a result of the pre-detonation, one miner received minor injuries, and the other miner received serious injuries.

Underground Quarry

MSHA offers the following Best Practices to help prevent this type of accident:

  • Explosive materials should be kept organized and under the direct observation of the blaster during loading operations so personnel and equipment do 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). 

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  • 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 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.

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