Which method is most suitable for highly fractured ore bodies?

Solution (By Examveda Team)

Definition:
Highly fractured ore bodies are ore deposits characterized by extensive fracturing and jointing, resulting in weak rock mass and potential instability.

Correct Answer: Sublevel Caving (A)
Sublevel caving is a method particularly well-suited for large, steeply dipping, and highly fractured ore bodies. This is because the method relies on the inherent instability of the fractured rock. The ore is extracted from sublevels, and the overlying ore is allowed to cave progressively. The fracturing facilitates this caving process, making it relatively easy to break down the ore and allowing for efficient extraction. The broken ore is drawn from the drawpoints at the bottom of the stopes.

Why other options are less suitable:
Shrinkage Stoping (B): While shrinkage stoping can handle some fracturing, it's less effective in highly fractured ground because the broken ore's self-supporting nature becomes unreliable in extremely fragmented conditions. Maintaining the stope walls becomes significantly more difficult, leading to instability and safety concerns.

Cut and Fill (C): Cut and fill requires relatively stable walls for effective operation. Highly fractured ore bodies lack this stability. The fill material would be lost into the fractures, rendering the method inefficient and potentially hazardous.

Room and Pillar (D): Room and pillar is suitable for relatively strong, less fractured ore bodies where pillars are left in place to support the roof. In highly fractured ore bodies, maintaining the integrity of the pillars would be challenging, leading to potential roof collapses and operational difficulties. The pillars would be weakened by the fracturing, rendering them ineffective for support.