Mine Development And Mining Methods — Part 2 MCQs with Explanations

Vertical interval is the distance between successive levels.The correct answer is: Vertical intervalIt affects haulage cost, ventilation, and stope design.Common values range from 30 to 60 meters depending on method.

Overbreak is unintentional excavation beyond the tunnel design profile.The correct answer is: Excess rock excavation beyond design limitsIt leads to extra ground support costs and instability.Caused by over-blasting or weak rock zones.

Jumbo drill is a mechanized drilling machine for tunnel and drift development.The correct answer is: Jumbo drillIt ensures precision drilling of blast holes in hard rock.Draglines are for surface mining; dredgers for marine mining.

Refuge chamber provides temporary shelter during emergencies like fire or gas leaks.The correct answer is: Emergency shelterIt is equipped with air supply, water, and communication devices.Crucial for miner safety in emergency evacuation plans.

Footwall is the rock mass beneath the ore body or vein.The correct answer is: Bottom surface below ore bodyThe rock above the ore is called the hanging wall.Important in structural analysis and access planning.

Ore grade is important for economic feasibility, but not a primary consideration for shaft siting.The correct answer is: Ore gradeFactors like geological stability, groundwater, and access are prioritized to ensure safe and cost-effective development.Ore grade influences mining methods, not necessarily shaft position.

Crosscut is a horizontal tunnel driven perpendicular to the main drift.The correct answer is: Accessing veins perpendicular to driftIt provides access to ore zones that are not aligned with the main tunnel.Essential in block caving and vein mining.

Adit is a horizontal or nearly horizontal passage driven from the surface.The correct answer is: AditUsed for access, drainage, and ventilation.Shafts are vertical; raises and winzes are internal vertical workings.

Timber sets are commonly used to support weak or fractured rock.The correct answer is: Timber setsComposed of vertical and horizontal wooden beams, they stabilize tunnels and stopes.Especially useful in narrow vein mines and older operations.

Skip is a shaft hoisting device used for transporting ore and waste.The correct answer is: SkipIt operates on a guide rail and works with hoisting engines.LHDs are for horizontal haulage, and drill jumbos for drilling.

Hydrostatic pressure reflects the pressure exerted by groundwater.The correct answer is: Hydrostatic pressureIt can cause water inflow during sinking, requiring dewatering or ground freezing.Important in selecting lining and sinking method.

A box cut is Option A: Initial open cut to access underground ore First, let's define what a box cut is in the context of mining engineering. A box cut is a type of open-pit mining operation. It's an initial excavation, typically rectangular or square in shape, used to gain access to underground ore bodies. The purpose of a box cut is to provide a surface opening for further underground development. From this initial opening, various underground mining methods can be employed to extract the ore. This approach is particularly useful when the ore body is situated beneath a layer of overburden (the layer of rock or soil above the ore deposit) that needs to be removed before underground workings can commence. Why other options are incorrect: Option B: A stoping method is incorrect. Stoping refers to a variety of underground mining methods where ore is extracted from a stope (an underground excavation). A box cut is not a stoping method itself; rather, it is a pre-requisite for accessing the underground area where stoping might later be used. Option C: A rock bolting technique is incorrect. Rock bolting is a ground support method used to reinforce and stabilize underground excavations. It's a separate technique used *after* access to the underground area has been established (e.g., via a box cut), not the access method itself. Option D: An ore pass support is incorrect. An ore pass is a chute or passageway used to transport ore from underground workings to the surface. Again, this is a feature of the underground mine *after* access has been gained; it is not the initial access method.

Exploration gallery is driven near the ore zone for observation and sampling.The correct answer is: Exploration galleryUsed to determine ore geometry, grade, and structure.Not a production-level drift.

Room and pillar is used in flat-bedded deposits like salt, coal, and potash.The correct answer is: Salt and potash miningRooms are mined, and pillars are left to support the roof.Not suitable for steep or irregular ore bodies.

Cut and Fill is an underground mining method using backfilling after each ore slice is removed.The correct answer is: Cut and FillEffective for irregular ore bodies and unstable ground.Allows high selectivity and safety.

Artificial ground freezing stabilizes wet, loose ground during shaft sinking.The correct answer is: Artificial ground freezingCirculates chilled brine or nitrogen through pipes to freeze surrounding soil.Minimizes water inflow and supports excavation.

Roadheader is used in soft to medium-hard rocks for continuous excavation.The correct answer is: RoadheaderIt uses a rotating cutting head and conveyor for spoil removal.Efficient in coal and evaporite mines.

Grizzly is a coarse screen at ore passes or chutes to block oversized material.The correct answer is: Sizing oversized materialPrevents large boulders from jamming crushers or loading equipment.Improves downstream efficiency.

Shrinkage Stoping is ideal for steep, narrow, high-grade ore bodies.The correct answer is: Shrinkage StopingBroken ore supports the stope walls and is removed later.Reduces dilution in narrow vein conditions.

Ladderway is a vertical or inclined passage fitted with ladders for worker movement.The correct answer is: Personnel movementUsed in emergency escape routes or where hoisting is unavailable.Not suitable for haulage or ventilation.

Decline ramps allow trucks and equipment to access the ore body without hoisting.The correct answer is: Continuous vehicular accessThis is ideal for shallow to medium-depth deposits.Shafts are more efficient for very deep mining.

Shotcrete is sprayed concrete used to support exposed rock surfaces.The correct answer is: Ground supportIt prevents rock falls and stabilizes tunnel walls and ceilings.Often combined with mesh and bolts.

Shrinkage Stoping is ideal for steep and narrow ore zones.The correct answer is: Shrinkage StopingBroken ore is stored in the stope to support walls and later extracted.Longwall is used in flat seams, especially coal.

Ore pass is a vertical or inclined passage used to move ore downward.The correct answer is: Transports ore to lower levels by gravityIt increases efficiency by reducing hauling distance.Proper design prevents blockages and wear.

Raise development involves upward excavation, which exposes workers to falling debris.The correct answer is: Falling rocks and materialProper scaling and support are essential to minimize risks.Raise climbers or raise boring machines reduce manual exposure.

Rill stoping uses elements of sublevel and shrinkage stoping.The correct answer is: Shrinkage stoping with sublevel stopingIt allows blasting from lower sublevels while using broken ore for wall support.Suited for moderately dipping ore bodies.

Sump is a low point where water is collected and pumped out.The correct answer is: Water drainage collectionIt prevents water buildup that can hinder operations or weaken ground.Essential for mine dewatering.

Block Caving is used for large, low-grade, horizontally extensive ore bodies.The correct answer is: Block CavingIt uses gravity to collapse ore, minimizing drilling and blasting.Low cost per ton but higher dilution.

Longwall mining is highly productive, especially for coal.The correct answer is: High initial capital costRequires expensive machinery and roof support systems.However, it offers good safety and recovery rates.

Ventilation raise is a vertical opening used for airflow.The correct answer is: Air circulationIt allows fresh air to enter and contaminated air to exit.Essential for maintaining breathable air underground.

Winze is a vertical or inclined shaft sunk from underground.The correct answer is: WinzeIt connects lower levels and is not visible from the surface (hence blind).Raise goes upward; adit is horizontal from surface.

Crown pillar is the rock left between mined-out stopes and the surface.The correct answer is: Acts as a safety barrier between stopes and surfacePrevents collapse and surface subsidence.Its design is critical for mine closure planning.

Cut and Fill uses backfill to support the stope, minimizing voids.The correct answer is: Cut and FillThis prevents ground movement and is ideal under sensitive areas like towns.Block caving causes extensive surface movement.

Raise borer drills vertical or inclined shafts between levels.The correct answer is: Creating vertical holesIt drills a pilot hole, then enlarges from below upward, creating smooth-walled shafts.Used in ventilation raises and ore passes.

Inclined conveyor belts are efficient for hauling ore in sloping tunnels.The correct answer is: Conveyor belt in inclineThey offer continuous, low-maintenance transport.Skips and cages are best suited for vertical shafts.

Muck bay is an enlarged section in a tunnel where blasted rock (muck) is temporarily stored.The correct answer is: Temporary ore storageIt provides space to load or haul ore without blocking the main tunnel.Not used for explosives or shelter.

Longwall mining is highly efficient for extracting flat, continuous seams.The correct answer is: Longwall miningIt uses a shearer and roof supports to extract large panels.Very common in coal mining.

Grouting involves injecting cementitious or chemical material into the ground.The correct answer is: GroutingIt fills fractures, reduces permeability, and strengthens rock mass.Essential near water-bearing or loose zones.

Shaft collar is the reinforced area at the top of a shaft.The correct answer is: Shaft mouth reinforcementIt prevents ground sloughing and provides support for hoisting gear.Usually made of concrete or steel.

Cut and fill mining allows selective extraction and tight control over ore boundaries.The correct answer is: Cut and fillBackfill supports the walls, reducing waste mixing.Used in high-grade, irregular ore zones.