Question

The machine used for drilling blast holes in hard rock mines is:

• A. Longwall shearer
• B. Continuous miner
• C. Jack hammer drill
• D. Belt conveyor

Hint:

Hard rock drilling for blasting is commonly done using jack hammer or pneumatic drills.

Answer 1

The Correct Option is C

Step 1: Understanding drilling requirements in hard rock mines.
In hard rock mining, blasting is required to break strong and compact rock formations. For this purpose, blast holes must be drilled accurately before charging explosives.
Step 2: Role of jack hammer drill.
A jack hammer drill is a portable percussive drilling machine designed specifically for drilling blast holes in hard rock. It uses impact force combined with rotation to penetrate hard rock efficiently.
Step 3: Analysis of the given options.
(A) Longwall shearer: Used for coal cutting in longwall mining, not for drilling.
(B) Continuous miner: Used mainly in coal mining for cutting and loading coal.
(C) Jack hammer drill: Correct — commonly used for drilling blast holes in hard rock mines.
(D) Belt conveyor: Used for material transportation, not drilling.
Step 4: Conclusion.
The most suitable machine for drilling blast holes in hard rock mines is the jack hammer drill.