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PEC EPE Mining practice questions

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Question 1Mining Engineering Practice (subject domain not enumerated in source)

In underground mining, what does the abbreviation 'RMR' stand for when classifying rock mass quality?

  1. Relative Mining Ratio
  2. Reinforced Mesh Requirement
  3. Rock Moisture Resistance
  4. Rock Mass Rating Correct answer.

Explanation

RMR is the Rock Mass Rating system, originally developed by Bieniawski, which combines parameters such as uniaxial compressive strength, RQD, joint spacing, joint condition, groundwater and orientation to assign a numerical class to a rock mass. It is widely used to select support systems and estimate stand-up time in underground openings.

Question 2Mining Engineering Practice (subject domain not enumerated in source)

Which drilling pattern term describes the holes drilled parallel to the tunnel axis that are fired first to create an initial free face for the remaining blast?

  1. Stoping holes
  2. Contour holes
  3. Cut holes Correct answer.
  4. Lifter holes

Explanation

Cut holes (often arranged as a burn cut or V-cut) are fired first and create the initial cavity and free face that allows subsequent holes to break efficiently. Without an adequate cut, the rest of the round has insufficient relief and blasting performance degrades.

Question 3Mining Engineering Practice (subject domain not enumerated in source)

A mine ventilation circuit reports an airflow of 60 m³/s through a drift with a pressure drop of 600 Pa. What is the approximate airpower consumed by that section of the circuit?

  1. 10 kW
  2. 360 kW
  3. 100 kW
  4. 36 kW Correct answer.

Explanation

Airpower equals airflow multiplied by pressure drop: 60 m³/s × 600 Pa = 36,000 W, or 36 kW. This is the theoretical power needed to move the air through that resistance; fan motor power will be higher because of fan and transmission efficiency.

Question 4Mining Engineering Practice (subject domain not enumerated in source)

What is the primary purpose of a tailings storage facility's supernatant pond management?

  1. To increase the density of the deposited tailings slurry
  2. To provide a permanent habitat for aquatic species
  3. To accelerate the oxidation of sulphide minerals
  4. To maximise water recovery and control the phreatic surface within the embankment Correct answer.

Explanation

Managing the supernatant pond keeps the water surface away from the embankment crest and controls the phreatic surface, which improves stability and allows water reuse in the process plant. A well-controlled beach and low pond reduce the risk of overtopping and seepage-driven instability.

Question 5Mining Engineering Practice (subject domain not enumerated in source)

In open pit mine design, the term 'stripping ratio' most commonly refers to which quantity?

  1. The ratio of ore tonnes milled to concentrate tonnes produced
  2. The ratio of waste tonnes (or volume) removed to ore tonnes (or volume) mined Correct answer.
  3. The ratio of bench height to bench width
  4. The ratio of explosive mass to rock volume blasted

Explanation

Stripping ratio expresses how much waste must be removed to access a unit of ore, and it is a key economic driver of pit limits and cut-off grade. It is often quoted as waste-to-ore by mass or by volume, so the units must be stated.

Question 6Mining Engineering Practice (subject domain not enumerated in source)

Which support element is installed to hold mesh and plates against the rock surface between primary rock bolts in a development heading?

  1. Cable bolt
  2. Mesh strap or w-plate with secondary bolts Correct answer.
  3. Split set
  4. Shotcrete fibre only

Explanation

Mesh straps or w-plates with secondary bolts retain the surface between primary bolts and prevent small blocks from loosening and falling. They complement, rather than replace, the primary reinforcing elements.

Question 7Mining Engineering Practice (subject domain not enumerated in source)

What does the term 'dilution' mean in the context of ore reserve estimation and grade control?

  1. The loss of fine particles during screening
  2. The decrease in metal price used in cut-off calculations
  3. The addition of water to the mill feed
  4. The reduction of ore grade caused by mixing of waste or low-grade material with ore Correct answer.

Explanation

Dilution is the contamination of ore with waste or sub-grade material during mining, which lowers the grade delivered to the mill and increases the tonnage treated. It is a major economic risk in both underground and open pit operations.

Question 8Mining Engineering Practice (subject domain not enumerated in source)

Which of the following best describes the role of a 'registrar' or statutory mine record in mining engineering practice?

  1. To certify the geotechnical model for slope design
  2. To carry out the daily blast design
  3. To maintain statutory plans, records and notifications required by the mining regulator Correct answer.
  4. To approve the mine's annual capital budget

Explanation

Statutory mine records, plans and notifications are kept to demonstrate compliance with the mining regulator's requirements and to support emergency response and audits. They are a legal and operational obligation of the mine operator.

Question 9Mining Engineering Practice (subject domain not enumerated in source)

A stope has a planned extraction of 120,000 t at 4.0 g/t Au, but grade control shows 12% dilution at 0.5 g/t. What is the approximate diluted grade delivered to the mill?

  1. 3.50 g/t
  2. 4.00 g/t
  3. 4.48 g/t
  4. 3.63 g/t Correct answer.

Explanation

With 12% dilution, the total mass is 120,000 × 1.12 = 134,400 t, and contained metal is 120,000 × 4.0 + 14,400 × 0.5 = 480,000 + 7,200 = 487,200 g. Dividing by 134,400 t gives about 3.63 g/t.

Question 10Mining Engineering Practice (subject domain not enumerated in source)

In sublevel stoping, why is a slot typically developed before production blasting begins?

  1. To drain groundwater from the stope
  2. To install the primary ventilation fan
  3. To allow the orepass to be surveyed
  4. To provide a free face and expansion space for the first production rings Correct answer.

Explanation

A slot creates an open void along the stope boundary so the first production rings can break toward a free face rather than being confined. Without a slot, the initial blasts would be heavily confined and produce poor fragmentation and possible damage.

Question 11Mining Engineering Practice (subject domain not enumerated in source)

A ventilation fan delivers 80 m³/s against 1,200 Pa at the fan. If the fan and motor combined efficiency is 70%, what is the approximate motor input power?

  1. 96 kW
  2. 69 kW
  3. 192 kW
  4. 137 kW Correct answer.

Explanation

Airpower is 80 × 1,200 = 96,000 W, or 96 kW. Dividing by the combined efficiency of 0.70 gives approximately 137 kW at the motor input.

Question 12Mining Engineering Practice (subject domain not enumerated in source)

Which condition most directly causes a reduction in the factor of safety of a pit wall after several years of operation?

  1. Extending the bench height on the opposite wall
  2. Reducing the haul truck payload
  3. Rising pore water pressure within the slope mass Correct answer.
  4. Increasing the blast powder factor in ore zones

Explanation

Rising pore water pressure reduces effective stress and therefore shear strength along potential failure surfaces, lowering the factor of safety. Depressurisation and drainage are therefore standard slope stability controls.

Question 13Mining Engineering Practice (subject domain not enumerated in source)

In a mine compressed air system, which practice most effectively reduces energy consumption?

  1. Removing aftercoolers to reduce pressure drop
  2. Running all compressors at part load continuously
  3. Increasing line pressure to compensate for leaks
  4. Repairing leaks and reducing system pressure to the minimum required Correct answer.

Explanation

Leaks are a major source of wasted compressed air, and reducing system pressure lowers compressor power because power scales with pressure. Running compressors at part load and removing aftercoolers are inefficient or unsafe practices.

Question 14Mining Engineering Practice (subject domain not enumerated in source)

A development round is drilled with 45 holes and a powder factor of 2.2 kg/m³. If the round volume is 90 m³, what mass of explosive is required?

  1. 99 kg
  2. 41 kg
  3. 198 kg Correct answer.
  4. 220 kg

Explanation

Explosive mass equals powder factor multiplied by round volume: 2.2 kg/m³ × 90 m³ = 198 kg.

Question 15Mining Engineering Practice (subject domain not enumerated in source)

Which method is most appropriate for dewatering a deep, high-permeability aquifer ahead of an underground development?

  1. Increasing ventilation flow through the heading
  2. Reducing the number of blast holes per round
  3. Applying shotcrete to the drift walls
  4. Installing surface dewatering wells and pumping from them Correct answer.

Explanation

Surface dewatering wells intercept groundwater before it reaches the workings and are effective in high-permeability aquifers. Shotcrete, ventilation and blast design do not remove water from the rock mass.

Question 16Mining Engineering Practice (subject domain not enumerated in source)

What is the key geotechnical concern when designing a crown pillar beneath an open pit that overlies underground workings?

  1. Reducing the pillar thickness to lower development cost
  2. Eliminating all support in the underlying stopes
  3. Ensuring the pillar thickness provides adequate stability against collapse and surface subsidence Correct answer.
  4. Maximising the pillar volume to increase ore recovery

Explanation

A crown pillar must be thick and strong enough to support the overburden and prevent collapse or subsidence that could affect the pit or surface infrastructure. Its design balances safety against the value of the ore it contains.

Question 17Mining Engineering Practice (subject domain not enumerated in source)

Which of the following is the most appropriate primary control for diesel particulate matter in an underground mine?

  1. Improving engine maintenance and ventilation, and using low-emission fuels or filters Correct answer.
  2. Increasing the number of loaded trucks in the drift
  3. Reducing the number of ventilation raises
  4. Increasing the use of open-flame heating

Explanation

Diesel particulate matter is controlled at source through engine maintenance, cleaner fuels, filters and after-treatment, and by diluting emissions with adequate ventilation. These measures directly reduce exposure in the workings.

Question 18Mining Engineering Practice (subject domain not enumerated in source)

A mine plans to backfill a stope with cemented hydraulic fill. Which property is most important to verify before placement?

  1. The unconfined compressive strength and slump or solids concentration of the mix Correct answer.
  2. The colour of the cement
  3. The brand of the delivery truck
  4. The temperature of the mixing water only

Explanation

Cemented fill must achieve the design strength for its exposed face and remain pumpable or flowable, so strength and rheology (slump or solids concentration) are the critical properties to verify. These control both stability and placement performance.

Question 19Mining Engineering Practice (subject domain not enumerated in source)

In a mine feasibility study, which cost category is typically treated as a capital cost rather than an operating cost?

  1. Drill bits consumed in production
  2. Grinding media consumed in the mill
  3. Diesel fuel for haul trucks
  4. Shaft sinking and headframe construction Correct answer.

Explanation

Shaft sinking and headframe construction are major fixed investments made before production, so they are capital costs. Consumables such as drill bits, fuel and grinding media are recurring and are treated as operating costs.

Question 20Mining Engineering Practice (subject domain not enumerated in source)

Which hazard is most specifically associated with the use of non-electric detonators in a development heading?

  1. Acid mine drainage generation
  2. Spontaneous combustion of the explosive
  3. Radon gas release from the explosive
  4. Misfires caused by cut-off shock tube or damaged lead-in lines Correct answer.

Explanation

Non-electric systems rely on shock tube or signal tube, which can be damaged or cut off by flyrock or ground movement, leading to misfires. Careful layout, stemming and post-blast inspection are used to manage this risk.

Question 21Mining Engineering Practice (subject domain not enumerated in source)

A concentrator treats 500 t/h of ore at 1.5% Cu to produce a concentrate at 25% Cu. Assuming no losses, what is the approximate concentrate production rate?

  1. 7.5 t/h
  2. 75 t/h
  3. 30 t/h Correct answer.
  4. 300 t/h

Explanation

Metal units in feed are 500 × 0.015 = 7.5 t/h of copper. At 25% concentrate grade, the concentrate rate is 7.5 / 0.25 = 30 t/h.

Question 22Mining Engineering Practice (subject domain not enumerated in source)

What is the principal purpose of a paste fill plant compared with a conventional hydraulic fill plant?

  1. To eliminate the need for any cementitious binder
  2. To produce a high-solids, low-water fill that reduces drainage and improves stope stability Correct answer.
  3. To increase the water content of the fill for easier pumping
  4. To reduce the strength of the placed fill

Explanation

Paste fill is prepared at high solids concentration so that it does not segregate or require large drainage systems, and it can be placed to form stable, self-supporting exposures. Conventional hydraulic fill carries more water and needs drainage.

Question 23Mining Engineering Practice (subject domain not enumerated in source)

A rock mass has an RQD of 40%, widely spaced joints and wet conditions. Using a qualitative interpretation of the RMR inputs, which description best fits the expected ground behaviour?

  1. Fair to poor rock requiring systematic support Correct answer.
  2. Rock that cannot be classified
  3. Very good rock requiring minimal support
  4. Extremely good rock with no support needed

Explanation

Low RQD, wide joint spacing and wet conditions all reduce the RMR score, placing the rock mass in a fair to poor category that typically needs systematic support. Good ratings require high RQD and dry, tight joints.

Question 24Mining Engineering Practice (subject domain not enumerated in source)

A stope is planned with a 15 m wide crown pillar at 300 m depth in a rock mass with a uniaxial compressive strength of 80 MPa. Which additional factor most strongly governs whether the pillar will remain stable?

  1. The type of drill used for development
  2. The colour of the pillar rock
  3. The joint orientation and persistence relative to the pillar walls Correct answer.
  4. The number of workers in the stope

Explanation

Pillar stability depends on the interaction of induced stress with discontinuities, so joint orientation and persistence relative to the pillar walls strongly control failure modes such as wedge sliding or slabbing. Intact rock strength alone is not sufficient for the assessment.

Question 25Mining Engineering Practice (subject domain not enumerated in source)

In a mine ventilation network, two parallel airways have resistances of 0.02 and 0.08 Ns²/m⁸. What is the approximate equivalent resistance of the parallel combination?

  1. 0.10 Ns²/m⁸
  2. 0.016 Ns²/m⁸
  3. 0.05 Ns²/m⁸
  4. 0.008 Ns²/m⁸ Correct answer.

Explanation

For parallel airways, 1/√R_eq = 1/√R₁ + 1/√R₂. Here 1/√0.02 ≈ 7.07 and 1/√0.08 ≈ 3.54, giving 10.61, so √R_eq ≈ 0.0943 and R_eq ≈ 0.0089, approximately 0.008 Ns²/m⁸.

Question 26Mining Engineering Practice (subject domain not enumerated in source)

In underground mining practice, what is the primary purpose of a hangingwall 'sill' or 'sill pillar' left at the base of a stope?

  1. To provide a stable working floor and support for the overlying stope during extraction Correct answer.
  2. To anchor the headframe foundation into competent rock
  3. To act as the main airway for secondary ventilation of the level
  4. To store broken ore temporarily before hoisting to surface

Explanation

A sill pillar is the horizontal rock mass left at the bottom of a stoping block to maintain a competent floor for mining, drilling and mucking operations above it. It also helps distribute stress and protect the level access. It is not a ventilation, ore storage or headframe element.

Question 27Mining Engineering Practice (subject domain not enumerated in source)

Which term describes the process of drilling and blasting a narrow vertical raise between two levels using a single pass of explosives?

  1. Longhole raise blasting Correct answer.
  2. Alimak raising
  3. Boxhole drilling
  4. Raise boring

Explanation

Longhole raise blasting uses long parallel holes drilled between levels and fired in sections or a single pass to create a raise. Raise boring and Alimak raising are mechanical methods, and boxhole drilling creates short raises without a lower access level.

Question 28Mining Engineering Practice (subject domain not enumerated in source)

What is the principal function of a 'brow' or 'muckpile brow' at the drawpoint of a sublevel cave?

  1. To inject cementitious grout into the caving rock mass
  2. To measure the tonnage of ore drawn from the stope
  3. To serve as the main return airway for the extraction level
  4. To control the flow of broken ore and protect the loader operator from falling rock Correct answer.

Explanation

The brow is the rock lip above a drawpoint that shapes ore flow and shields personnel and equipment from loose rock in the muckpile. It is a geotechnical and safety control, not a measurement or ventilation device, and grouting is a separate ground-control activity.

Question 29Mining Engineering Practice (subject domain not enumerated in source)

In mine surveying, what does a 'break line' represent on a survey plan of a development drive?

  1. A boundary where the surveyed excavation changes direction or cross-section Correct answer.
  2. A legal mining lease boundary
  3. A line marking the water table
  4. A fault that offsets the orebody

Explanation

A break line on a survey plan marks a distinct change in geometry of the excavation, such as a corner, grade change or cross-section transition. Faults, lease boundaries and water tables are separate geological, legal and hydrogeological features.

Question 30Mining Engineering Practice (subject domain not enumerated in source)

Which gas is the principal asphyxiant produced by the oxidation of coal and by blasting in underground coal workings, and is monitored as a standard atmospheric hazard?

  1. Hydrogen sulfide
  2. Sulfur dioxide
  3. Carbon monoxide Correct answer.
  4. Methane

Explanation

Carbon monoxide is a colourless asphyxiant produced by incomplete combustion, blasting and spontaneous heating of coal. Methane is flammable rather than a simple asphyxiant in the same sense, and hydrogen sulfide and sulfur dioxide are toxic irritant gases from other sources.

Question 31Mining Engineering Practice (subject domain not enumerated in source)

What is the primary purpose of a 'sump' at the bottom of an underground shaft or decline?

  1. To act as a surge bin for ore hoisting
  2. To provide a refuge chamber for emergencies
  3. To collect water so it can be pumped to surface Correct answer.
  4. To store spare ground support materials

Explanation

A shaft or decline sump collects groundwater and seepage at the lowest point so that pumps can remove it. It is not a storage area for materials, a refuge chamber or an ore bin, which are separate facilities.

Question 32Mining Engineering Practice (subject domain not enumerated in source)

Which document in mining engineering practice defines the sequence, timing and resources for developing and mining each ore block?

  1. The environmental management plan
  2. The exploration drilling log
  3. The geological resource statement
  4. The mine plan or mining schedule Correct answer.

Explanation

The mine plan or schedule sets out the sequence, timing and resources for developing and extracting ore blocks. Resource statements quantify geology, environmental plans manage impacts, and drilling logs record exploration data.

Question 33Mining Engineering Practice (subject domain not enumerated in source)

In underground mining, which support element is installed between primary rock bolts to hold mesh and plates against the rock surface?

  1. Secondary or split-set bolts with face plates Correct answer.
  2. Steel mesh with wire lacing
  3. Shotcrete with welded mesh
  4. Cable slings and timber blocking

Explanation

Secondary bolts with face plates provide additional fastening points between primary rock bolts. The plates clamp the mesh against the rock surface, helping retain loose fragments. The mesh itself is the retained surface-support material, whereas the bolt and plate provide the fastening.

Question 34Mining Engineering Practice (subject domain not enumerated in source)

A development round is drilled with 42 holes and a powder factor of 2.4 kg/m³. If the round volume is 75 m³, what mass of explosive is required?

  1. 180 kg Correct answer.
  2. 150 kg
  3. 210 kg
  4. 200 kg

Explanation

Explosive mass equals powder factor multiplied by round volume: 2.4 kg/m³ × 75 m³ = 180 kg. The other values do not follow from this product.

Question 35Mining Engineering Practice (subject domain not enumerated in source)

A stope is planned to extract 90,000 t at 3.5 g/t Au. Grade control indicates 10% dilution at 0.4 g/t. What is the diluted grade delivered to the mill?

  1. 3.50 g/t
  2. 3.73 g/t
  3. 3.10 g/t
  4. 3.22 g/t Correct answer.

Explanation

The diluted grade is the weighted average of ore and dilution: (90,000 × 3.5 + 9,000 × 0.4) / 99,000 = (315,000 + 3,600) / 99,000 = 3.22 g/t. The undiluted grade ignores the waste, and the other values do not follow from the weighting.

Question 36Mining Engineering Practice (subject domain not enumerated in source)

A concentrator treats 400 t/h of ore at 1.2% Cu and produces a concentrate at 24% Cu with no losses. What is the approximate concentrate production rate?

  1. 48 t/h
  2. 10 t/h
  3. 20 t/h Correct answer.
  4. 40 t/h

Explanation

Metal units in feed equal 400 × 0.012 = 4.8 t/h Cu. Dividing by the concentrate grade gives 4.8 / 0.24 = 20 t/h of concentrate. The other rates do not follow from this mass balance.

Question 37Mining Engineering Practice (subject domain not enumerated in source)

A ventilation fan delivers 60 m³/s against 1,500 Pa at the fan. If the combined fan and motor efficiency is 75%, what is the approximate electrical power drawn?

  1. 150 kW
  2. 135 kW
  3. 90 kW
  4. 120 kW Correct answer.

Explanation

Air power equals flow times pressure: 60 × 1,500 = 90,000 W = 90 kW. Dividing by 0.75 efficiency gives 120 kW electrical input. The other values do not correctly apply the efficiency.

Question 38Mining Engineering Practice (subject domain not enumerated in source)

Two parallel airways in a ventilation network have resistances of 0.03 and 0.12 Ns²/m⁸. What is the approximate equivalent resistance of the parallel combination?

  1. 0.045 Ns²/m⁸
  2. 0.150 Ns²/m⁸
  3. 0.019 Ns²/m⁸ Correct answer.
  4. 0.024 Ns²/m⁸

Explanation

For parallel airways, 1/√R = 1/√R1 + 1/√R2. Here 1/√0.03 ≈ 5.77 and 1/√0.12 ≈ 2.89, giving 8.66, so R = 1/8.66² ≈ 0.019 Ns²/m⁸. The other values do not follow from the parallel resistance relationship.

Question 39Mining Engineering Practice (subject domain not enumerated in source)

A rock mass has an RQD of 35%, widely spaced joints and wet conditions. Which qualitative RMR band is most consistent with these observations?

  1. Fair rock
  2. Very good rock
  3. Poor rock Correct answer.
  4. Good rock

Explanation

Low RQD, widely spaced joints and wet conditions all reduce the RMR score, placing the rock mass in the poor category. Very good and good ratings require high RQD and dry, favourable joint conditions.

Question 40Mining Engineering Practice (subject domain not enumerated in source)

Which condition most directly reduces the factor of safety of an open pit wall several years after mining begins?

  1. Increased truck haulage on the ramp
  2. Progressive pore pressure increase and weathering along persistent discontinuities Correct answer.
  3. Reduction in blast hole diameter
  4. Installation of additional horizontal drains

Explanation

Rising pore pressure reduces effective stress and shear strength, while weathering degrades discontinuity surfaces, both lowering the factor of safety over time. Horizontal drains improve stability, and blast hole diameter and haulage do not directly govern wall stability.

Question 41Mining Engineering Practice (subject domain not enumerated in source)

Which practice most effectively reduces energy consumption in an underground mine compressed air system?

  1. Repairing leaks and reducing system pressure to the minimum required Correct answer.
  2. Operating compressors at maximum discharge pressure continuously
  3. Adding more air receivers without fixing leaks
  4. Running compressors at part load with inlet throttling

Explanation

Leaks waste a large share of compressed air, and lowering discharge pressure reduces compressor power. Fixing leaks and minimising pressure is the most effective measure. High pressure, extra receivers without leak repair and inlet throttling do not address the root inefficiency.

Question 42Mining Engineering Practice (subject domain not enumerated in source)

A stope is to be backfilled with cemented hydraulic fill. Which property is most important to verify before placement to ensure the fill will support the exposed face?

  1. The colour of the tailings used in the mix
  2. The particle size of the cement powder only
  3. The pH of the mixing water only
  4. The unconfined compressive strength of cured fill at the required binder content Correct answer.

Explanation

The cured unconfined compressive strength at the design binder content determines whether the fill can support exposures and overburden loads. Colour, water pH alone and cement particle size are not sufficient design criteria.

Question 43Mining Engineering Practice (subject domain not enumerated in source)

Which of the following is treated as a capital cost rather than an operating cost in a mine feasibility study?

  1. Wages of the grade control geologists
  2. Purchase and installation of the primary crusher Correct answer.
  3. Diesel consumed by the haul fleet
  4. Replacement ground support consumables

Explanation

Capital costs are the initial investments in infrastructure and equipment, such as purchasing and installing a primary crusher. Diesel, wages and consumables are recurring operating costs.

Question 44Mining Engineering Practice (subject domain not enumerated in source)

What is the principal advantage of a paste fill plant over a conventional hydraulic fill plant?

  1. It removes the need for a tailings thickener
  2. It allows a higher solids concentration and reduces water and cement demand while limiting barricade loads Correct answer.
  3. It produces fill that never needs curing
  4. It eliminates the need for any binder in the fill

Explanation

Paste fill is prepared at high solids concentration, which reduces water input, cement consumption and the loads on barricades. It still requires binder and thickening, and it must cure like other cemented fills.

Question 45Mining Engineering Practice (subject domain not enumerated in source)

A crown pillar 12 m thick separates an open pit from underlying stopes at 250 m depth. Which factor most governs its stability?

  1. The ratio of pillar thickness to span and the rock mass strength Correct answer.
  2. The size of the pit office building
  3. The number of trucks on the pit ramp
  4. The colour of the ore being mined

Explanation

Crown pillar stability depends mainly on the geometry (thickness relative to span) and the rock mass strength, which together govern the factor of safety. Ore colour, truck numbers and surface buildings do not control pillar stability.

Question 46Mining Engineering Practice (subject domain not enumerated in source)

In a feasibility study, which method is most appropriate for estimating the capital cost of a unique, first-of-its-kind processing facility with limited historical data?

  1. Factored estimate from a similar plant
  2. Historical cost per tonne of ore
  3. Detailed bottom-up estimate from engineering design Correct answer.
  4. Parametric scaling from throughput only

Explanation

For a unique facility with limited historical analogues, a detailed bottom-up estimate based on engineering design is the most reliable. Factored, parametric and historical per-tonne methods rely on analogues that may not represent the design.

Question 47Mining Engineering Practice (subject domain not enumerated in source)

A stope has a planned extraction of 150,000 t at 2.8 g/t Au. Grade control shows 15% dilution at 0.3 g/t. What is the diluted grade delivered to the mill?

  1. 2.80 g/t
  2. 2.30 g/t
  3. 2.48 g/t Correct answer.
  4. 2.95 g/t

Explanation

Diluted grade = (150,000 × 2.8 + 22,500 × 0.3) / 172,500 = (420,000 + 6,750) / 172,500 ≈ 2.48 g/t. The undiluted grade is 2.80 g/t, and the other values do not follow from the weighted average.

Question 48Mining Engineering Practice (subject domain not enumerated in source)

In an underground mine, two parallel airways have resistances of 0.05 and 0.20 Ns²/m⁸. What is the approximate equivalent resistance and how does it compare with the lower individual resistance?

  1. About 0.022 Ns²/m⁸, lower than either individual resistance Correct answer.
  2. About 0.080 Ns²/m⁸, between the two resistances
  3. About 0.250 Ns²/m⁸, higher than both
  4. About 0.050 Ns²/m⁸, equal to the lower resistance

Explanation

For parallel airways, pressure drops are equal and flows add. With ΔP = RQ², 1/√R_eq = 1/√0.05 + 1/√0.20 ≈ 6.71, so R_eq ≈ 0.0222 Ns²/m⁸. The equivalent resistance is lower than either individual resistance.

Question 49Mining Engineering Practice (subject domain not enumerated in source)

A paste fill stope requires 8,000 m³ of fill at a binder content of 4% by mass. If the fill dry density is 1.8 t/m³, what mass of binder is required?

  1. 320 t
  2. 576 t Correct answer.
  3. 144 t
  4. 1,440 t

Explanation

Dry fill mass = 8,000 × 1.8 = 14,400 t. Binder mass = 4% of 14,400 = 576 t. The other values arise from misapplying the density or the binder percentage.

Question 50Mining Engineering Practice (subject domain not enumerated in source)

A mine plans to dewater a deep, high-permeability aquifer ahead of underground development. Which approach is most appropriate?

  1. Relying solely on sump pumps at the development face
  2. Increasing ventilation to evaporate the water
  3. Installing a network of dewatering boreholes with pumps to lower the piezometric surface before development Correct answer.
  4. Sealing the aquifer with shotcrete at the face

Explanation

For a deep, high-permeability aquifer, a network of dewatering boreholes with pumps can lower the piezometric surface in advance of development. Face sumps, shotcrete sealing and ventilation do not control a large aquifer inflow.