Q138
What is the purpose of a crown pillar in underground mining?
A.
Provide ventilation
B.
Support overlying rock mass
AnswerC.
Drain water
D.
Guide drilling
Answer: Option B
Solution
Answer: Option B
Solution:
Crown pillar is a layer of unmined rock left between an underground mine and the surface.The correct answer is: Support overlying rock massIt prevents collapse and surface subsidence.Critical in near-surface deposits.