Mine Development And Mining Methods - Study Mode

[#186] Which mining method involves retreating the face and allowing the roof to collapse behind?
Correct Answer

(B) Longwall mining

Explanation

Solution: Longwall mining is common in coal mining with high productivity.The correct answer is: Longwall miningPowered supports advance with the face while the roof collapses in the gob area.This method is highly mechanized.

[#187] What is the purpose of a crown pillar in underground mining?
Correct Answer

(B) Support overlying rock mass

Explanation

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.

[#188] Which of the following is best suited for selective mining in irregular ore bodies?
Correct Answer

(C) Cut and fill

Explanation

Solution: Cut and fill mining adapts to irregular ore shapes and allows selective extraction.The correct answer is: Cut and fillOre is removed in slices and the void is backfilled.High cost but minimal dilution.

[#189] Which factor most affects the stability of underground openings?
Correct Answer

(B) Rock strength

Explanation

Solution: Rock strength is a primary determinant of how stable an opening will be.The correct answer is: Rock strengthStronger rocks can support wider spans and deeper development.Measured through RQD and UCS tests.

[#190] What is the purpose of an ore pass?
Correct Answer

(C) Ore transfer between levels

Explanation

Solution: Ore pass : An ore pass is a vertical or inclined chute used in underground mining operations to transport extracted ore from one level of the mine to another. Correct Answer: Option C: Ore transfer between levels The primary purpose of an ore pass is to facilitate the efficient and safe movement of broken ore from upper mining levels to lower levels, where it can be collected and transported to the surface for processing. Ore passes are typically constructed of concrete or steel and are designed to withstand the abrasive nature of the ore and the substantial forces involved in transporting large volumes of material. They often incorporate features such as chutes, gates, and loading points to control the flow of ore. Why other options are incorrect: Option A: Water drainage : While some ore passes might incidentally help drain water, this is not their primary function. Water drainage in mines is usually handled by dedicated systems, such as sumps and pumps. Option B: Waste storage : Waste rock (or tailings) is usually disposed of in designated areas, separate from ore passes. Storing waste in ore passes would hinder their primary function and potentially cause blockages. Option D: Air circulation : Mine ventilation is managed through separate ventilation shafts and systems. Ore passes are not designed for air circulation and could even obstruct airflow if improperly managed.