Question

During development of Metalliferous deposits, the pillar left in its in-situ condition to protect upper level is known as

• A. Crown pillar
• B. Sill pillar
• C. Rib pillar
• D. Barrier

Hint:

Remember the location relative to the stope (the excavated room):
- Crown is at the top (like a crown on a head).
- Sill is at the bottom (like a window sill).
- Rib is on the side (like a rib cage).

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question asks for the specific name of a pillar that is left between the top of a stope and the mining level above it.

Step 2: Detailed Explanation:
In underground metal mining, different types of pillars are left for support:
-

Crown Pillar: This is the pillar of rock or ore left above a stope to provide support to the floor of the level immediately above it.
It forms the "crown" of the stope.
This directly matches the description in the question.
-

Sill Pillar: This is the pillar of rock or ore left at the bottom of a stope, forming its floor or "sill" above the level below.
-

Rib Pillar: These are pillars left between adjacent stopes to support the side walls.
-

Barrier Pillar: These are very large pillars left to separate major mining panels or to protect main roadways and shafts from the stresses of extraction areas.

Step 3: Final Answer:
The pillar left to protect the upper level is known as a crown pillar.
This corresponds to option (A).