MSHA Explosives and Blasting 2

Question 1

What is 'flyrock' in the context of surface mine blasting, and what is the primary MSHA concern?

Accepted Answer

Rock propelled beyond the intended blast area, posing a hazard to workers and the public

Answer

Flyrock refers to rock fragments thrown beyond the designated blast zone, which is a significant hazard that can injure workers, bystanders, and damage property.

Question 2

According to MSHA regulations, the magazine used to store explosives at a mine must be:

Accepted Answer

Located a safe distance from roads, occupied buildings, and other magazines per MSHA tables

Answer

MSHA regulations specify minimum separation distances from magazines to roads, buildings, and other magazines based on the quantity of explosives stored, as detailed in published distance tables.

Question 3

What is a 'bootleg' in blasting terminology, and why is it dangerous?

Accepted Answer

An unbroken portion of a borehole remaining after a blast that may contain undetonated explosives

Answer

A bootleg is the remaining portion of a drill hole after a blast, and it is dangerous because it may contain unexploded explosive material that could detonate if disturbed during subsequent drilling.

Question 4

Under MSHA standards, electric blasting circuits must be tested before firing using:

Accepted Answer

A blasting galvanometer or approved circuit tester designed for explosives use

Answer

Only a blasting galvanometer or an approved, low-current circuit tester designed specifically for explosives use may be used, as other devices can deliver enough current to accidentally detonate electric blasting caps.

Question 5

What is 'sympathetic detonation' in the context of explosives storage?

Accepted Answer

The accidental detonation of an explosive charge caused by the shock wave of a nearby explosion

Answer

Sympathetic detonation occurs when the shock wave from one explosion is strong enough to set off nearby explosive charges, which is why MSHA requires minimum separation distances between magazines.

MSHA - Mine Safety and Health Administration Practice Test

MSHA - Mine Safety and Health Administration Practice Test

MSHA Explosives and Blasting 2