Mine Development and Mining Methods MCQs Questions & Answers | Mining Engineering

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.

Room and Pillar Mining:
Room and pillar mining is a mining method where ore is extracted by creating a grid of rooms separated by pillars of ore. These pillars support the overlying rock and prevent cave-ins. After the rooms are mined, the pillars may be subsequently extracted, depending on the stability of the ground and mining goals. This subsequent extraction of the pillars is the key to understanding the question.

Retreat Mining:
Retreat mining is the correct answer. In retreat mining, the rooms are initially mined leaving the pillars in place. These pillars then provide support for the overlying strata. Once mining in a section is complete, the pillars are systematically removed in a planned retreat, allowing the overlying ground to subside in a controlled manner. This controlled subsidence is important for ground stability and safety.

Why other options are incorrect:
Primary Stoping: This is a method of underground mining typically used in steeply dipping orebodies, not related to room and pillar techniques.
Forward Mining: This involves mining in a continuous advance, typically without leaving pillars for later extraction. It's opposite to retreat mining.
Sublevel Mining: This method involves creating a series of horizontal sublevels in an orebody, it does not involve the room and pillar layout and pillar extraction characteristic of this question.

Blasting pattern design involves planning hole spacing and charge size.The correct answer is: Blasting pattern designControls fragmentation size, safety, and wall stability.Essential for production and development blasts.

Cut and fill mining allows selective extraction and backfilling.The correct answer is: Cut and fillMinimizes mixing of ore and waste.Ideal for narrow, irregular ore bodies.

Shaft stations are horizontal access points from vertical shafts.The correct answer is: A level access point from a shaftUsed for loading, unloading, and level transitions.Usually reinforced and well-lit for safety.

Checkerboard patterns are typical in room and pillar layouts.The correct answer is: CheckerboardEnsures structural support and access throughout the mine.Optimizes ore recovery and ventilation.

Ore dilution is related to ore mixing, not a direct shaft hazard.The correct answer is: Ore dilutionShaft hazards include falling rock, water inflow, and gas.Proper lining and ventilation reduce risks.

Longwall mining uses shearers and roof supports for continuous operation.The correct answer is: Longwall miningPrimarily used in coal mining.High productivity and automation.

Mucking units load and transport broken rock or ore.The correct answer is: Ore transportIncludes LHDs, loaders, or conveyors.Critical for efficient stope clearing.

Reamer head is attached after a pilot hole is drilled.The correct answer is: Enlarge pilot holesRotates from bottom to top, enlarging the raise.Produces smooth, stable openings for ventilation or ore movement.