Basic Mining interview questions

150 questions with answers (MIN-001 to MIN-150). Try each one aloud before reading the answer.

Mining Geology & Exploration

MIN-001 · What is the difference between an ore and a mineral?

A mineral is a naturally occurring, inorganic solid with a definite chemical composition and crystal structure. An ore is a mineral deposit from which a valuable constituent can be extracted at a profit under current economic conditions.

MIN-002 · What is gangue?

Gangue is the valueless mineral matter (such as quartz, calcite or silicates) associated with the valuable mineral in an ore. It is separated and rejected during mineral processing.

MIN-003 · What are strike and dip?

Strike is the direction of a horizontal line on an inclined bed or vein surface. Dip is the maximum angle of inclination of that surface from the horizontal, measured perpendicular to the strike.

MIN-004 · What are the hanging wall and footwall of an ore body?

For an inclined ore body, the hanging wall is the rock lying above it and the footwall is the rock lying below it. The terms come from a miner standing in the vein with the hanging wall overhead.

MIN-005 · What is a fault, and what are its main types?

A fault is a fracture along which rocks have moved relative to each other. Main types are normal (hanging wall moves down), reverse or thrust (hanging wall moves up) and strike-slip (horizontal movement along strike).

MIN-006 · What is the difference between an anticline and a syncline?

An anticline is an upward, arch-shaped fold with the oldest beds in its core. A syncline is a downward, trough-shaped fold with the youngest beds in its core.

MIN-007 · What is a placer deposit?

A placer is a concentration of heavy, durable minerals (gold, cassiterite, ilmenite, monazite, diamond) formed by weathering and gravity sorting in rivers, beaches or alluvium. India's beach sand ilmenite–monazite deposits in Kerala and Odisha are examples.

MIN-008 · What is the difference between diamond core drilling and reverse circulation (RC) drilling?

Core drilling recovers an intact cylindrical rock core, giving geological structure, rock quality and accurate assays. RC drilling recovers crushed chips through the inner tube of a dual-wall rod; it is faster and cheaper but gives no core.

MIN-009 · What is core recovery?

Core recovery is the length of core recovered divided by the length drilled, expressed as a percentage. Low recovery indicates broken, weathered or soft ground and reduces confidence in assay results.

MIN-010 · What is the grade of an ore?

Grade is the concentration of the valuable constituent in the ore, expressed as a percentage (e.g. % Cu, % Fe) for base metals or grams per tonne (g/t) for precious metals.

MIN-011 · Name the main geophysical methods used in mineral exploration.

Magnetic, gravity, electrical resistivity, induced polarisation (IP), electromagnetic (EM), seismic and radiometric surveys. The choice depends on the contrast in physical property between the target and host rock.

MIN-012 · What is a gossan?

A gossan is a rusty, iron-oxide-rich weathered capping formed over a sulphide ore body by oxidation and leaching. It is a classic surface indicator used by prospectors to locate buried sulphide deposits.

MIN-013 · What are the stages of mineral exploration under UNFC?

Reconnaissance (G4), prospecting (G3), general exploration (G2) and detailed exploration (G1). Each stage uses closer sampling and drilling, increasing geological confidence in the deposit.

Mine Development

MIN-014 · What is the difference between a shaft, an adit and an incline?

A shaft is a vertical or steeply inclined opening from the surface. An adit is a near-horizontal tunnel driven into a hillside from the surface. An incline is an inclined opening, usually driven along the dip of the deposit.

MIN-015 · What is the difference between a drift and a crosscut?

A drift is a horizontal opening driven along the strike of the ore body. A crosscut is a horizontal opening driven across the strike, usually connecting the shaft to the ore body or connecting drifts.

MIN-016 · What is the difference between a raise and a winze?

Both are vertical or steep openings connecting two levels. A raise is driven upward from a lower level; a winze is sunk downward from an upper level.

MIN-017 · What is a level in an underground mine?

A level is a system of horizontal workings (drifts, crosscuts) at a particular elevation from which an ore body is developed and worked. Levels are typically spaced at regular vertical intervals and linked to the shaft.

MIN-018 · What is a headframe (headgear)?

A headframe is the structure over a shaft that carries the sheave wheels over which the winding ropes pass. It is built from steel or concrete and must be high enough to allow overwind clearance.

MIN-019 · What is a pit bottom (shaft inset)?

The pit bottom is the enlarged area around the shaft at a working level where cages or skips are loaded and unloaded. It houses facilities such as the onsetter's station, sump access and sometimes pump rooms.

MIN-020 · What is a shaft pillar?

A shaft pillar is a block of mineral left unmined around a shaft to protect it, and nearby surface structures, from ground movement. Its size depends on depth, seam dip and rock properties.

MIN-021 · What is a sump in a mine?

A sump is a low-lying excavation, usually at the shaft bottom or lowest level, where mine water collects so it can be pumped to the surface.

MIN-022 · What is a decline (ramp)?

A decline is an inclined tunnel from the surface (or within the mine) that allows rubber-tyred trackless vehicles such as trucks and LHDs to access the ore body. It is usually driven at a gradient of about 1 in 7 to 1 in 9.

MIN-023 · Name the main methods of shaft sinking.

Conventional drill-and-blast sinking, and special methods for weak or water-bearing ground: ground freezing, cementation (grouting), drop or caisson shaft and shaft boring. Blind-shaft boring and raise boring are mechanised options.

MIN-024 · What is the difference between a skip and a cage?

A skip is a container that carries broken rock or coal up the shaft and discharges it automatically. A cage carries men, materials and mine cars.

MIN-025 · What is the difference between development and stoping?

Development is driving the access openings (shafts, levels, raises) needed to reach and prepare the ore body. Stoping is the actual extraction of ore from the prepared blocks.

MIN-026 · Why are shafts lined?

Lining (concrete, steel tubbing or brickwork) supports the shaft walls, prevents rock falls, controls water ingress and provides a smooth surface for fixing buntons and guides. Shafts are the lifeline of a mine and must stay stable for its whole life.

Surface Mining

MIN-027 · What is the difference between open-pit and underground mining?

Open-pit mining removes overburden to extract shallow deposits from the surface; it is cheaper, safer, more productive and gives higher recovery. Underground mining reaches deeper deposits through shafts or declines; it has higher unit cost and risk but disturbs less land.

MIN-028 · What is the stripping ratio?

The stripping ratio is the quantity of waste (overburden) removed per unit of ore or coal mined, expressed as t/t, m³/t or m³/m³. For example, 5 m³ of overburden per tonne of coal is a stripping ratio of 5:1.

MIN-029 · What is overburden?

Overburden is the soil and rock lying above an ore body or coal seam that must be removed to expose it in surface mining. It is dumped in external or in-pit dumps.

MIN-030 · What are a bench, bench height and berm in an open pit?

A bench is a step-like ledge cut in the pit wall. Bench height is the vertical distance between two benches. A berm is a horizontal ledge left on the wall to catch rolling rocks and improve slope stability.

MIN-031 · What is the ultimate pit limit?

The ultimate pit limit is the final boundary of an open pit beyond which further mining is uneconomic. It defines the maximum extent of the pit at the end of mine life.

MIN-032 · What is strip mining?

Strip mining is surface mining of flat-lying, shallow seams in long parallel strips, where overburden from each new strip is cast into the void of the previous one. It is common in coal and is usually done with draglines.

MIN-033 · What is a dragline?

A dragline is a large excavator that swings a bucket on hoist and drag ropes from a long boom. It is used for overburden removal in strip mines and casts waste directly into the mined-out void without trucks.

MIN-034 · What is a shovel–dumper system?

It is the most common surface mining system: a rope or hydraulic shovel loads broken material into rear-dump trucks (dumpers), which haul it to the crusher, stockpile or dump.

MIN-035 · What is a haul road?

A haul road is the road on which dumpers carry ore and waste in a surface mine. It is designed for width, gradient, curve radius, drainage, safety berms and wearing course to ensure safe, efficient haulage.

MIN-036 · What is swell factor?

Swell factor is the ratio of in-situ (bank) density to loose density, or equivalently loose volume to bank volume. Broken rock occupies more volume than in place, so equipment capacities must be corrected for swell.

MIN-037 · What is quarrying?

Quarrying is surface extraction of building stone, dimension stone, limestone or aggregates. Dimension-stone quarries use wire saws and splitting to recover intact blocks rather than blasting to fragment.

MIN-038 · What is a surface miner?

A surface miner is a machine with a rotating cutting drum that cuts, crushes and loads coal or soft rock in thin layers without drilling and blasting. It is widely used in Indian opencast coal mines to reduce blasting near habitation.

MIN-039 · What is highwall mining?

Highwall mining uses a remotely controlled continuous-miner head to drive unsupported parallel entries into a coal seam exposed in the final highwall of an opencast mine. It recovers coal that would otherwise be left behind once stripping becomes uneconomic.

Underground Coal Mining

MIN-040 · What is the bord and pillar method?

In bord and pillar (room and pillar), a seam is divided into pillars by driving a network of galleries (bords) at right angles. Development forms the pillars; they are later extracted (depillaring) or left as permanent support.

MIN-041 · What is the longwall method?

Longwall mining extracts coal along a long face (typically 150–300 m or more) using a shearer, armoured face conveyor and powered roof supports. The roof behind the supports is allowed to cave as the face advances.

MIN-042 · What is the difference between advancing and retreating longwall?

In advancing longwall, gate roads are formed as the face moves away from the main roads. In retreating longwall, the gate roads are driven to the panel boundary first and the face retreats back toward the mains. Retreating is preferred for better ventilation, gas control and proving of the panel.

MIN-043 · What is depillaring?

Depillaring is the extraction of pillars formed during bord and pillar development, usually by splitting them into smaller stooks and slicing. The roof is then caved or the void filled by stowing.

MIN-044 · What is the difference between caving and stowing?

In caving, the roof over the extracted area is allowed to collapse. In stowing, the void is filled with sand or other material, usually hydraulically, to support the roof and limit surface subsidence.

MIN-045 · What are powered roof supports?

Powered roof supports are hydraulic shields or chock-shields that hold up the roof at a longwall face and advance automatically with the face. They protect the face crew and push the armoured face conveyor forward.

MIN-046 · What are a shearer and an armoured face conveyor (AFC)?

A shearer is a cutting machine with rotating drums that travels along the longwall face cutting coal. The AFC is a heavy chain conveyor along the face that carries the cut coal to the main gate and guides the shearer.

MIN-047 · What is a continuous miner?

A continuous miner is a machine with a rotating cutter drum that cuts and loads coal in one operation, without drilling and blasting. It is used in bord and pillar development and depillaring, with shuttle cars and roof bolters.

MIN-048 · What is coal rank?

Rank is the degree of coalification. In increasing rank: peat, lignite, sub-bituminous, bituminous and anthracite. Carbon content and calorific value generally increase with rank, while moisture and volatile matter decrease.

MIN-049 · What is proximate analysis of coal?

Proximate analysis determines moisture, volatile matter, ash and fixed carbon (by difference). It is used for coal grading and quality control.

MIN-050 · What is the difference between coking and non-coking coal?

Coking coal softens, swells and resolidifies on heating without air to form strong porous coke for blast furnaces. Non-coking coal lacks this property and is used mainly as thermal coal for power generation.

MIN-051 · What is goaf (gob)?

Goaf is the mined-out area behind a longwall face or a depillared panel, where the roof has caved or the void has been stowed.

MIN-052 · What are the normal gallery dimensions in Indian bord and pillar workings?

Under Indian coal mine regulations, gallery width should normally not exceed 4.8 m and height 3 m, unless DGMS permits otherwise. Pillar size is prescribed against depth and gallery width.

Underground Metal Mining

MIN-053 · Name some common underground mining methods.

Room and pillar, longwall, sublevel stoping, cut and fill, shrinkage stoping, sublevel caving and block caving. They are chosen by ore body geometry, rock strength and economics.

MIN-054 · What is a stope?

A stope is the underground excavation from which ore is extracted in a metal mine. Its shape and size depend on the stoping method and ore body geometry.

MIN-055 · What is shrinkage stoping?

In shrinkage stoping, ore is mined upward in horizontal slices and the broken ore is left in the stope as a working platform. Only the swell (about 35–40%) is drawn during mining; the rest is drawn at the end.

MIN-056 · What is cut and fill stoping?

Ore is mined in horizontal slices, usually upward, and each mined slice is backfilled with waste, sand or paste before the next slice is taken. It suits irregular, steep ore bodies with weak walls and gives high selectivity.

MIN-057 · What is sublevel stoping?

Sublevel stoping uses sublevels to drill long holes into the ore, which is blasted into a large open stope and drawn from drawpoints at the bottom. It needs competent ore and wall rock and is highly productive.

MIN-058 · What is block caving?

Block caving undercuts a large ore block so it caves under gravity; the broken ore is drawn from drawpoints below. It is a low-cost, high-tonnage method for large, massive, low-grade ore bodies.

MIN-059 · What is sublevel caving?

Ore is drilled and blasted from sublevels while the hanging wall caves to fill the void. Broken ore is drawn under caved waste, so dilution is high, but the method is cheap and highly mechanised.

MIN-060 · When is room and pillar used in metal mines?

It is used for flat or gently dipping (usually under about 30°), tabular ore bodies with competent roof, such as some limestone, lead-zinc and salt deposits. Pillars of ore are left for support.

MIN-061 · What is dilution in mining?

Dilution is waste or low-grade material mixed with the ore during mining, which increases tonnage and lowers the grade sent to the mill. It is usually expressed as waste tonnes ÷ total tonnes mined.

MIN-062 · What is ore recovery (mining recovery)?

Mining recovery is the percentage of the planned ore actually extracted. Losses come from pillars, ore left in stopes and ore misclassified as waste.

MIN-063 · What is a drawpoint?

A drawpoint is an opening at the bottom of a stope or cave through which broken ore is loaded, usually by an LHD.

MIN-064 · What is an ore pass?

An ore pass is a vertical or steep raise through which broken ore is dropped by gravity from upper levels to a haulage level or crusher. It reduces horizontal tramming.

MIN-065 · What types of backfill are used in underground mines?

Rock fill, hydraulic (sand or classified tailings) fill, cemented rock fill and paste fill. Fill supports the walls, allows pillar recovery, reduces subsidence and disposes of tailings underground.

Rock Mechanics & Ground Control

MIN-066 · What is rock mechanics?

Rock mechanics is the study of the mechanical behaviour of rock and rock masses under stress. In mining, it is used to design stable openings, pillars, slopes and support.

MIN-067 · What is uniaxial compressive strength (UCS)?

UCS is the maximum axial stress a cylindrical rock specimen can carry under unconfined compression. It is a basic input to rock mass classification and pillar design, measured in MPa.

MIN-068 · What is RQD?

Rock Quality Designation (Deere) is the sum of lengths of intact core pieces 10 cm or longer divided by the total core run, expressed as a percentage. Higher RQD means less fractured rock.

MIN-069 · How is vertical in-situ stress estimated?

Vertical stress is usually taken as the weight of overlying rock: σv = γ·H. With a unit weight of about 0.025–0.027 MN/m³, σv increases by roughly 0.025–0.027 MPa per metre of depth.

MIN-070 · What is a pillar's factor of safety?

It is the ratio of pillar strength to the average stress acting on the pillar. Values well above 1 (often 1.5–2 for long-term pillars) are used to allow for variability.

MIN-071 · What is roof bolting?

Roof bolting installs steel bolts into drilled holes in the roof to bind laminated strata, suspend weak layers from stronger beds and reinforce the rock mass. Bolts are anchored mechanically, with resin or with cement grout.

MIN-072 · What is convergence in underground openings?

Convergence is the closure of an opening as the roof, floor and sides move toward each other. It is monitored with convergence indicators or tape extensometers to detect instability.

MIN-073 · What is the Mohr–Coulomb failure criterion?

It states that shear failure occurs when the shear stress on a plane reaches τ = c + σn·tan φ, where c is cohesion, σn is normal stress and φ is the friction angle.

MIN-074 · What are Young's modulus and Poisson's ratio of rock?

Young's modulus E is the ratio of axial stress to axial strain in the elastic range. Poisson's ratio ν is the ratio of lateral to axial strain. Both are obtained from the uniaxial compression test.

MIN-075 · What is a discontinuity in rock?

A discontinuity is any plane of weakness in a rock mass, such as a joint, bedding plane, fault or foliation. Its orientation, spacing, persistence and condition largely control rock mass strength.

MIN-076 · What is shotcrete?

Shotcrete is concrete sprayed at high velocity onto a rock surface to form a supporting layer. It may be fibre-reinforced and is often combined with rock bolts and mesh.

MIN-077 · What is the Brazilian test?

The Brazilian test measures indirect tensile strength by loading a rock disc diametrically until it splits. Tensile strength σt = 2P/(πDt), where P is failure load, D diameter and t thickness.

MIN-078 · What is abutment pressure?

Abutment pressure is the increased stress on the solid coal or rock around an excavation, caused by load transferred from the mined-out area. In longwall mining, it peaks a few metres ahead of the face and along the panel sides.

Drilling & Blasting

MIN-079 · What is powder factor?

Powder factor is the quantity of explosive used per unit of rock broken, expressed in kg/m³ or kg/t. It is a key indicator of blast efficiency and cost.

MIN-080 · What are burden and spacing in bench blasting?

Burden is the distance from a blasthole to the nearest free face (or to the next row). Spacing is the distance between adjacent holes in the same row. Together they define the volume of rock broken per hole.

MIN-081 · What is stemming?

Stemming is inert material (drill cuttings or crushed aggregate) placed in the top of a charged hole to confine the explosive gases. It improves energy use and reduces flyrock and airblast.

MIN-082 · What is subdrilling?

Subdrilling is drilling a hole below the planned bench floor level, typically about 0.3 times the burden. It ensures the toe breaks cleanly and avoids hard toe on the floor.

MIN-083 · What is ANFO?

ANFO is a blasting agent of about 94% ammonium nitrate prills and 6% fuel oil by weight, which is close to oxygen balance. It is cheap and safe to handle but has poor water resistance.

MIN-084 · What are permitted explosives?

Permitted explosives are explosives approved for use in gassy underground coal mines. They have low flame temperature and short flame duration so they do not ignite firedamp or coal dust. In India they are classified as P1, P3 and P5 by their test performance.

MIN-085 · What types of detonators are used in mining?

Plain (with safety fuse), electric instantaneous, electric delay (millisecond and half-second), non-electric shock-tube (NONEL) and electronic detonators. Electronic detonators give the most accurate timing.

MIN-086 · What is detonating fuse (cord)?

Detonating cord is a flexible plastic tube with a core of PETN that detonates at about 6,500–7,000 m/s. It is used to initiate charges in several holes or to connect holes on the surface.

MIN-087 · What is a misfire?

A misfire is a charge that fails to detonate fully or partly after initiation. It must be handled by a competent shotfirer after a statutory waiting period, following prescribed procedures, as it is a serious hazard.

MIN-088 · What is the difference between rotary, percussive and down-the-hole (DTH) drilling?

Rotary drilling breaks rock by crushing and cutting with a rotating bit under heavy thrust, suiting soft to medium rock. Percussive (top-hammer) drilling chips rock by repeated blows from a hammer at the surface. In DTH, the hammer sits behind the bit at the bottom of the hole, reducing energy loss in deep holes.

MIN-089 · What is flyrock?

Flyrock is rock thrown unexpectedly far from a blast. It is caused by insufficient burden or stemming, weak zones or overcharging, and is a major cause of blasting accidents and damage.

MIN-090 · What is a cut in tunnel or drift blasting?

A cut is the group of holes fired first at the centre of the face to create a free face for the remaining holes. Common types are the wedge (V) cut, fan cut and burn (parallel hole) cut.

Mine Ventilation & Gases

MIN-091 · What is firedamp?

Firedamp is methane (CH₄), with traces of other hydrocarbons, released from coal seams. It is colourless, odourless and lighter than air, so it tends to accumulate near the roof.

MIN-092 · What are blackdamp, whitedamp, stinkdamp and afterdamp?

Blackdamp is oxygen-deficient air rich in CO₂ and N₂. Whitedamp is carbon monoxide. Stinkdamp is hydrogen sulphide. Afterdamp is the toxic gas mixture left after a fire or explosion, mainly CO, CO₂ and N₂.

MIN-093 · What are the main types of mine ventilation fans?

Axial-flow fans (air moves parallel to the shaft, with adjustable blade angle) and centrifugal fans (air enters axially and leaves radially). Main fans are usually axial in modern mines; auxiliary fans are also axial.

MIN-094 · What is natural ventilation?

Natural ventilation is airflow caused by the difference in air density between intake and return shafts, due to temperature and elevation differences. It varies with season and can aid or oppose the main fan.

MIN-095 · What are intake and return airways?

Intake airways carry fresh air from the surface to the working places. Return airways carry contaminated air from the workings back to the upcast shaft or fan.

MIN-096 · What are stoppings, doors, regulators and air crossings?

Stoppings are permanent walls that block airflow between intake and return. Doors allow passage while limiting leakage. Regulators are adjustable openings that control the quantity in a split. Air crossings let one airstream pass over another without mixing.

MIN-097 · What is auxiliary ventilation?

Auxiliary ventilation uses small fans and ducting to ventilate dead-end headings that the main circuit cannot reach. It can be forcing (blowing fresh air to the face), exhausting (drawing air out) or overlap combinations.

MIN-098 · What is a flame safety lamp used for?

It is used to detect methane and oxygen deficiency. Methane forms a pale blue flame cap above the reduced flame whose height indicates concentration, while the flame dims or goes out in oxygen-deficient air.

MIN-099 · Why is carbon monoxide dangerous in mines?

CO is colourless, odourless and binds to haemoglobin about 200–300 times more strongly than oxygen, preventing oxygen transport. It is produced by fires, spontaneous heating, blasting and diesel engines and is the main killer after explosions.

MIN-100 · How are Indian coal seams classified by degree of gassiness?

Degree I: methane in the general body of air below 0.1% and emission rate up to 1 m³/t. Degree II: emission 1–10 m³/t. Degree III: emission above 10 m³/t. Higher degrees require stricter ventilation and flameproof equipment.

MIN-101 · What is the minimum oxygen content required in mine air?

Mine air in working places must contain at least 19% oxygen by volume under Indian regulations. Normal air has about 20.9% oxygen.

MIN-102 · How is air quantity measured in a mine airway?

Air quantity Q = A × v, where A is the airway cross-section (m²) and v is the mean air velocity (m/s), giving Q in m³/s. Velocity is measured with a vane anemometer by traversing the airway.

Mine Machinery & Transport

MIN-103 · What is an LHD?

A Load-Haul-Dump machine is a low-profile, articulated, rubber-tyred loader that loads broken ore, carries it in its bucket and dumps it into an ore pass or truck. It is the workhorse of trackless underground metal mines.

MIN-104 · What is the difference between a rope shovel and a hydraulic shovel?

A rope (electric) shovel uses wire ropes and electric motors for hoist and crowd; it has long life and low operating cost. A hydraulic shovel uses hydraulic cylinders, has higher digging force and selectivity and is more mobile, but costs more to maintain.

MIN-105 · What is a rear-dump truck (dumper)?

A rear-dump truck is an off-highway haul truck with a body that tips backward to discharge. Capacities range from about 35 t to over 400 t; they are the main haulage units in open-pit mines.

MIN-106 · What are the main components of a belt conveyor?

Belt, drive pulley and motor, tail pulley, idlers (carrying and return), take-up (tensioning) unit, scrapers, chutes and safety devices such as pull-cord switches and belt-sway switches.

MIN-107 · What is the difference between a drum winder and a Koepe (friction) winder?

A drum winder coils the rope on a drum. A Koepe winder passes the rope over a friction wheel with the conveyances counterbalanced, and uses tail ropes; it is lighter and suits deep shafts with multiple ropes.

MIN-108 · What types of rope haulage are used underground?

Direct rope haulage, main-and-tail rope haulage and endless rope haulage. They move tubs or mine cars along roadways, especially in inclined roadways in older coal mines.

MIN-109 · What types of locomotives are used underground?

Trolley-wire electric, battery electric, diesel and compressed-air locomotives. Battery and flameproof diesel locomotives are preferred in gassy mines because trolley wires can cause sparks.

MIN-110 · What is a shuttle car?

A shuttle car is a rubber-tyred electric vehicle with a built-in chain conveyor that carries coal from a continuous miner to a feeder-breaker or belt in bord and pillar mining.

MIN-111 · What is flameproof (FLP) equipment?

Flameproof equipment has an enclosure that withstands an internal explosion of flammable gas and prevents the flame from passing through its joints to ignite the surrounding atmosphere. It is required in gassy coal mines.

MIN-112 · What is intrinsically safe equipment?

Intrinsically safe equipment limits electrical energy in its circuits so that any spark or thermal effect cannot ignite a flammable atmosphere, even under fault conditions. It suits low-power devices such as gas monitors and communication systems.

MIN-113 · What types of pumps are used for mine dewatering?

Centrifugal pumps (multistage for high heads), submersible pumps for shafts and sumps, and positive-displacement pumps (reciprocating or diaphragm) for slurries and high heads at low flows.

MIN-114 · What is a bucket wheel excavator?

A bucket wheel excavator is a continuous digging machine with buckets mounted on a rotating wheel at the end of a boom. It feeds conveyors directly and suits soft overburden or lignite, as in Neyveli lignite mines.

Mine Planning, Valuation & Economics

MIN-115 · What is the difference between a mineral resource and a mineral reserve?

A resource is a concentration of material with reasonable prospects for eventual economic extraction. A reserve is the economically mineable part of a measured or indicated resource after applying mining, processing, economic, legal and environmental modifying factors.

MIN-116 · What are measured, indicated and inferred resources?

They are resource categories of decreasing geological confidence. Measured is based on closely spaced data, indicated on moderately spaced data, and inferred on limited sampling that can only imply continuity.

MIN-117 · What are proved and probable reserves?

A proved reserve is the economically mineable part of a measured resource. A probable reserve comes from an indicated (or sometimes measured) resource with lower confidence. Inferred resources cannot be converted to reserves.

MIN-118 · What is a block model?

A block model divides the deposit into a 3D grid of blocks, each holding estimated grade, density, rock type and value. It is the basis for pit optimisation, mine design and scheduling.

MIN-119 · What is life of mine (LOM)?

Life of mine is the period over which the reserve will be extracted at the planned production rate. Approximately, LOM = mineable reserve ÷ annual production.

MIN-120 · What is net present value (NPV)?

NPV is the sum of all future cash flows discounted to the present at a chosen discount rate, minus the initial investment: NPV = Σ CFₜ/(1+i)ᵗ − C₀. A positive NPV means the project earns more than the discount rate.

MIN-121 · What is a royalty in mining?

A royalty is a payment to the mineral owner (in India, the state government) for minerals extracted. It may be a fixed rate per tonne or a percentage of the mineral value.

MIN-122 · What is a mining lease?

A mining lease is the legal grant from the government giving the right to mine a mineral in a defined area for a specified period. In India, mineral concessions are granted under the MMDR Act 1957, now mainly through auctions.

MIN-123 · What is a mining plan in India?

A mining plan is a statutory document describing geology, reserves, mining method, production, development, environmental management and progressive closure. For non-coal major minerals it is approved by the Indian Bureau of Mines; for coal by the Ministry of Coal.

MIN-124 · What is the UNFC code of a resource?

The United Nations Framework Classification codes a resource by three axes: economic viability (E), feasibility (F) and geological knowledge (G). For example, 111 is a proved reserve, economically viable, feasible and fully explored.

MIN-125 · What is a mine closure plan?

A mine closure plan sets out how the site will be made safe, stable and rehabilitated during operation (progressive closure) and after mining ends (final closure), with financial assurance to cover the cost.

MIN-126 · How is ore tonnage calculated from volume?

Tonnage = volume × in-situ (bulk) density. For example, 1,000,000 m³ of ore at 2.8 t/m³ gives 2.8 Mt.

Mine Safety & Legislation

MIN-127 · What does the Mines Act 1952 regulate?

It regulates health, safety and welfare of persons employed in mines in India. It covers working hours, employment age, inspection, competent persons, reporting of accidents, welfare amenities and the powers to make regulations and rules.

MIN-128 · What are CMR and MMR?

CMR are the Coal Mines Regulations (current version 2017) and MMR are the Metalliferous Mines Regulations 1961. Both are framed under the Mines Act 1952 and lay down detailed technical safety requirements for coal and non-coal mines.

MIN-129 · What working hours are allowed under the Mines Act 1952?

No adult may work more than 48 hours a week, nor more than 9 hours a day above ground or 8 hours a day below ground, subject to the Act's provisions on overtime and spread-over.

MIN-130 · What is the minimum age for employment in a mine in India?

The Mines Act 1952 prohibits employment of anyone below 18 years in any part of a mine. Apprentices and trainees of at least 16 years may be allowed under supervision.

MIN-131 · Name the statutory competent persons in an Indian mine.

Mine manager, assistant manager, overman, mining mate or sirdar, foreman, shotfirer or blaster, surveyor, winding engine driver and gas testing personnel, each holding the certificate required by regulations.

MIN-132 · What is a self-rescuer?

A self-rescuer is personal breathing apparatus carried by underground workers for escape. Filter self-rescuers convert CO to CO₂ but need adequate oxygen; self-contained self-rescuers supply oxygen independently of the surrounding air.

MIN-133 · What is a mines rescue station?

A rescue station keeps trained rescue brigades, breathing apparatus and equipment ready to respond to fires, explosions and inundations. In India, they are established under the Mines Rescue Rules 1985.

MIN-134 · Who is a workmen's inspector?

A workmen's inspector is a person nominated from among workers in larger mines to inspect workings for safety, report hazards to the manager and record findings. The role gives workers a direct voice in safety.

MIN-135 · What is a safety committee in a mine?

A safety committee is a joint body of management and worker representatives that meets regularly to review accidents, hazards and safety measures and to recommend improvements.

MIN-136 · What is mine inundation?

Inundation is a sudden inrush of water into mine workings, often from old waterlogged workings, rivers or aquifers. It is a major disaster hazard, controlled by accurate plans, barriers and advance (probe) boreholes.

MIN-137 · What is the purpose of the Mines Vocational Training Rules 1966?

They require basic, refresher and special training for mine workers at vocational training centres before and during employment, so that workers understand hazards, safe practices and first aid.

MIN-138 · What is a Safety Management Plan (SMP) in Indian mines?

An SMP is a risk-based document, encouraged by DGMS, that identifies the hazards of a particular mine, assesses risks and sets control measures, responsibilities and monitoring. It moves safety from prescriptive compliance toward risk management.

Mineral Processing & Mine Environment

MIN-139 · What is comminution?

Comminution is size reduction of ore by crushing and grinding to liberate valuable minerals from gangue. It is the most energy-intensive step in mineral processing.

MIN-140 · Name the main types of crushers.

Primary: jaw and gyratory crushers. Secondary and tertiary: cone crushers, roll crushers, impact and hammer crushers. High-pressure grinding rolls (HPGR) are also used before grinding.

MIN-141 · Name the main types of grinding mills.

Ball mills, rod mills, autogenous (AG) and semi-autogenous (SAG) mills, and vertical stirred mills for fine grinding.

MIN-142 · What is the difference between screening and classification?

Screening separates particles by size using a mechanical aperture, for coarse sizes. Classification separates finer particles by their settling velocity in a fluid, using hydrocyclones or mechanical classifiers.

MIN-143 · What is froth flotation?

Froth flotation makes the valuable mineral surfaces hydrophobic with collectors so they attach to air bubbles and rise into a froth, while hydrophilic gangue stays in the pulp. It is the main method for sulphide ores.

MIN-144 · What is gravity concentration?

Gravity concentration separates minerals by differences in specific gravity using jigs, spirals, shaking tables, heavy-medium separation and centrifugal concentrators. It is used for coal, gold, tin and iron ore.

MIN-145 · What is magnetic separation?

Magnetic separation uses differences in magnetic susceptibility. Low-intensity separators recover strongly magnetic minerals such as magnetite; high-intensity separators recover weakly magnetic ones such as hematite and ilmenite.

MIN-146 · What are concentrate and tailings?

Concentrate is the product enriched in the valuable mineral. Tailings are the rejected material, mainly gangue, discharged to a tailings storage facility.

MIN-147 · What is liberation?

Liberation is the freeing of valuable mineral grains from gangue by size reduction. The grind size needed for adequate liberation controls the energy cost and achievable recovery.

MIN-148 · What is acid mine drainage (AMD)?

AMD is acidic, metal-laden water formed when sulphide minerals such as pyrite oxidise in contact with air and water. It contaminates streams and groundwater and can continue long after mining ends.

MIN-149 · What is environmental clearance for a mine in India?

It is the approval from the Ministry of Environment, Forest and Climate Change (or state authority) under the EIA Notification 2006, based on an Environmental Impact Assessment, public hearing and an environmental management plan.

MIN-150 · What is mine reclamation?

Reclamation is restoring mined land to a stable, productive use by backfilling, reshaping, replacing topsoil, revegetation and drainage control. It is done progressively during operations and at closure.

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