MSHA Explosives and Blasting 1 — Questions and Answers
Question 1: Under MSHA regulations, who is authorized to handle and use explosives in underground mines?
- Any miner with at least 5 years of experience
- A certified blaster who holds a valid blaster's certificate (Correct answer)
- The mine foreman or shift supervisor only
- Any employee who has completed a 4-hour safety course
Correct answer: A certified blaster who holds a valid blaster's certificate
MSHA 30 CFR Part 57 requires that only certified blasters who hold a valid blaster's certificate are authorized to handle and use explosives in underground metal and nonmetal mines.
Question 2: What is the minimum distance that must be maintained between detonators (blasting caps) and other explosives during transportation in a mine?
- 6 inches
- 12 inches
- At least 50 feet
- Detonators must be transported separately from other explosives (Correct answer)
Correct answer: Detonators must be transported separately from other explosives
MSHA regulations require that electric detonators and other explosives be transported separately to prevent accidental initiation.
Question 3: Before loading explosives into a borehole, MSHA requires that the hole be checked with which of the following?
- A metal tamping rod
- A wooden or non-sparking loading stick (Correct answer)
- A steel probe to detect water
- A voltage tester for stray currents
Correct answer: A wooden or non-sparking loading stick
MSHA requires the use of a non-conductive, non-sparking wooden or plastic loading stick to prevent accidental detonation when loading explosives.
Question 4: According to MSHA standards, what must be done if a misfire (failed blast) is suspected in an underground coal mine?
- Re-enter the blast area after 5 minutes
- Wait at least 30 minutes before returning and follow specific misfire procedures (Correct answer)
- Immediately flood the area with water
- Send a single trained employee to inspect after 10 minutes
Correct answer: Wait at least 30 minutes before returning and follow specific misfire procedures
MSHA regulations require miners to wait at least 30 minutes before re-entering an area with a suspected misfire and to follow strict procedures to safely handle the unexploded charge.
Question 5: What type of container is required by MSHA for storing electric detonators (blasting caps) at a mine site?
- A locked wooden box painted red
- A separate locked magazine, apart from other explosives (Correct answer)
- A plastic bucket with a sealed lid
- A metal locker inside the main explosive magazine
Correct answer: A separate locked magazine, apart from other explosives
MSHA regulations require that electric detonators be stored in a separate locked magazine away from other explosives to reduce the risk of sympathetic detonation.
Question 6: Under MSHA rules for underground coal mines (30 CFR Part 75), permissible explosives are required because they:
- Are cheaper than standard industrial explosives
- Produce a flame and gas that will not ignite coal dust or methane (Correct answer)
- Can be detonated without electric blasting caps
- Are waterproof and can be used in wet conditions
Correct answer: Produce a flame and gas that will not ignite coal dust or methane
Permissible explosives are specially formulated so that their detonation flame and gases will not ignite coal dust or methane gas, which is critical for safety in gassy coal mines.
Question 7: What does MSHA require regarding the posting of warning signs during blasting operations?
- Signs are optional if verbal warnings are given
- Warning signs must be posted at all entrances to the blast area before detonation (Correct answer)
- Signs must be posted only when blasting near a public road
- A single sign at the mine entrance is sufficient
Correct answer: Warning signs must be posted at all entrances to the blast area before detonation
MSHA requires that warning signs be posted at all entrances to the blast area to prevent unauthorized personnel from entering during blasting operations.
MSHA Explosives and Blasting 1
Under MSHA regulations, who is authorized to handle and use explosives in underground mines?