U of S GEOE498.3 Fall2010 lecture2.pdf

University of SaskatchewanUniversity of Saskatchewan

Geological EngineeringGeological EngineeringGEOE 498.3GEOE 498.3

Introduction to Mineral EngineeringIntroduction to Mineral Engineering

Lecture 2Lecture 2

•• Underground Mining MethodsUnderground Mining Methods–– Bulk vs. SelectiveBulk vs. Selective–– Reasons for Selection (Geotechnical, Geometry, Value, Grade, Reasons for Selection (Geotechnical, Geometry, Value, Grade,

Dilution Control, Skill of work force, health and safety, etc)Dilution Control, Skill of work force, health and safety, etc)–– Mining Equipment (mobile)Mining Equipment (mobile)–– Tunneling MethodsTunneling Methods

Underground Mining MethodsUnderground Mining Methods

• MINING METHOD Is defined as the manner of extraction of an ore deposit underground and depends on many factors.

• Different Methods are used for Hardrock and Softrock as well as Bulk and Selective Mining

Factors to ConsiderFactors to Consider

•• Geological and Geotechnical Geological and Geotechnical Considerations Considerations –– Strength of OreStrength of Ore–– Strength of host rockStrength of host rock–– Stress fieldStress field–– Structural Geology (faults, contacts, Structural Geology (faults, contacts,

joints, folds, etc.)joints, folds, etc.)–– Dimensions of Dimensions of orebodyorebody (thickness, strike (thickness, strike

length, height)length, height)–– Orientation (dip, plunge)Orientation (dip, plunge)–– DepthDepth

Factors to ConsiderFactors to Consider

•• Economic and LogisticalEconomic and Logistical–– Availability of Skilled Availability of Skilled LabourLabour–– Availability of EquipmentAvailability of Equipment–– Availability of backfillAvailability of backfill–– Legacy issuesLegacy issues–– Health and Safety factorsHealth and Safety factors–– EconomicsEconomics

• Production Requirements • Value of ore• Operating Cost• Capital cost• Processing cost

Common Requirements for all Common Requirements for all Mining MethodsMining Methods

•• Access for equipment, personnel, Access for equipment, personnel, services (electricity, water, compressed services (electricity, water, compressed air, ventilation).air, ventilation).

•• Arteries for the transport of ore & waste Arteries for the transport of ore & waste out of the mine and possibly backfill into out of the mine and possibly backfill into the mine.the mine.

•• DrainageDrainage•• safe working conditionssafe working conditions

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Classification of Classification of Mining MethodsMining Methods

Choice of Mining Method will impact

• Orebody recovery and Dilution• Amount of development needed• Capital requirement and operating

costs• Type of equipments required• Cycle time and sequence of operations • Production (tonnes per year)• Risk

Classification of Underground Mining Methods

• Two main Classes of Underground Mining Methods:–Bulk Mining (Caving, Open Stoping, VCR)–Selective Mining (Cut and Fill, Room and Pillar, Shrinkage)

•• Overhand Overhand StopingStoping –– Bottom Up Bottom Up Method Method

•• Underhand Underhand StopingStoping –– Top Down Top Down Method Method

•• Longitudinal Longitudinal StopingStoping –– Long axis of Long axis of stopestope is parallel to is parallel to orebodyorebody strikestrike

•• Transverse Transverse StopingStoping –– Long axis of Long axis of stopestope is perpendicular to is perpendicular to orebodyorebodystrikestrike

Sub-Classifications

Sub-Classifications

•• Underhand Underhand StopingStoping–– Stability of the Stability of the OrebodyOrebody is very poor or there is no is very poor or there is no

access to the lower part of the access to the lower part of the orebodyorebody–– Examples: Underhand Cut and Fill used in narrow veins Examples: Underhand Cut and Fill used in narrow veins

at depth or underhand Blast hole open at depth or underhand Blast hole open stopingstoping used for used for bulk mining.bulk mining.

–– Workers are always standing on solid ore and below Workers are always standing on solid ore and below supported or filled back.supported or filled back.

•• Overhand Overhand StopingStoping–– StopingStoping operation start a the bottom of the operation start a the bottom of the orebodyorebody and and

proceeds to upwardproceeds to upward–– Most popular method of Most popular method of stopingstoping. Example: Shrinkage . Example: Shrinkage

stopingstoping, Cut and Fill , Cut and Fill stopesstopes, Room and Pillar, Caving , Room and Pillar, Caving Methods, VCR Method of Mining, Sub Level Methods, VCR Method of Mining, Sub Level StopingStoping

Hard Rock Selective Mining Hard Rock Selective Mining MethodsMethods

•• Room and PillarRoom and Pillar•• Cut and FillCut and Fill•• ShrinkageShrinkage•• AlimakAlimak MiningMining•• Raise bore and Box hole MiningRaise bore and Box hole Mining

Room and PillarRoom and Pillar• Applicable to relatively flat orebodies and employ natural support

(rock pillars). The orebody is excavated as completely as possible leaving ore/waste as pillars to support the hanging wall (back).Dimensions of the stopes and pillars depend upon factors such as the stability of the back, stability of the ore, thickness of the deposit and rock stresses.

– Horizontal Mining is the most commonly used room and pillar method. It is applicable to horizontal or near horizontal deposits (< 5° dip) and to inclined deposits of greater thickness, with the floor arranged for a moderate slope that allows for use of mobile equipment.

– Inclined Mining is for inclined orebodies (20° - 30° dip). Stopingproceeds upwards along the dip direction. The steep slope precludes use of mobile equipment.

– Step Mining adapts horizontal stoping to an inclined orebody (20° - 45°dip). This is a recent development in the industry for mining orebodies that would otherwise be precluded by their steep dip. It requires a special layout of stopes and a sequence of extraction resulting in the use of mobile equipment.

Horizontal Room and PillarHorizontal Room and Pillar

Inclined Room and PillarInclined Room and Pillar

Step Room and PillarStep Room and Pillar

Room and PillarRoom and Pillar

Room and PillarRoom and Pillar

Room and Pillar FeaturesRoom and Pillar Features

•• Summary of ApplicationsSummary of Applications–– relatively flat relatively flat orebodiesorebodies–– limited thicknesslimited thickness–– competent hanging wall and ore competent hanging wall and ore

•• Advantages ...Advantages ...–– good productivitygood productivity–– moderate costmoderate cost–– flexible method, amenable to mechanizationflexible method, amenable to mechanization–– SelectiveSelective–– minimal early developmentminimal early development–– No backfill requiredNo backfill required

•• Disadvantages ...Disadvantages ...–– possible ground control problemspossible ground control problems–– Medium to low recovery, ore lost in pillarsMedium to low recovery, ore lost in pillars

Cut and FillCut and Fill•• Cut and fill Cut and fill stopingstoping methods excavate ore in horizontal methods excavate ore in horizontal

slices or lifts, starting at the bottom of a slices or lifts, starting at the bottom of a stopestope and and advancing upwards.advancing upwards.

•• The broken ore is removed from the The broken ore is removed from the stopestope after each lift is after each lift is blasted.blasted.

•• After a slice is mucked out, the void is filled with backfill. After a slice is mucked out, the void is filled with backfill. The fill supports the walls and provides a working platform The fill supports the walls and provides a working platform for mining the next lift.for mining the next lift.

•• Fill material can consist of waste rock however, it is more Fill material can consist of waste rock however, it is more common to use tailings from the mill transported to mine in common to use tailings from the mill transported to mine in slurry form.slurry form.

•• When water in the fill is drained off a competent fill with a When water in the fill is drained off a competent fill with a smooth surface is produced. In some cases the material is smooth surface is produced. In some cases the material is mixed with cement to provide a harder and more durable mixed with cement to provide a harder and more durable surface with improved support characteristics.surface with improved support characteristics.

•• Suited to steeply dipping, irregular Suited to steeply dipping, irregular orebodiesorebodies, weak host , weak host rock or large tabular steeply dipping irregular rock or large tabular steeply dipping irregular orebodiesorebodies for for multiple lifts or cutsmultiple lifts or cuts

Cut and FillCut and Fill

Cut and Fill Cut and Fill



Longitudinal MCFLongitudinal MCF

Longitudinal MCFLongitudinal MCF

Transverse Transverse MCFMCF



• Summary of application– orebody width 2m - 30m– tabular shape ... good for irregular

orebodies– orebody dip 35o - 90o

– good for low strength / high stress regions

– requires safe, stable back for man entry– Expensive, generally high grade ore

required for this method to be economic– good selectivity minimum dilution


• Advantage…– moderate production and scale– good selectivity– low development cost– adaptable to mechanization– flexible method– excellent recovery with low dilution– tailings can be disposed of as fill

• Disadvantage…– high production cost– fill complicates cycle– requires stope access for mechanized equipment– labour intensive– ground settlement/instability risk

Cut and Fill VariationsCut and Fill Variations

• Underhand Cut and Fill or Undercut and Fill– Developed to recover pillars or to mine low strength ore

bodies– Mining top down and placing a cemented/reinforced mat

over the working area ... enabling mining below.

• Drift and Fill– Used to mine wide, flat, thin (<6m) orebodies with poor

hanging wall conditions.Mining involves a series of parallel drifts with an access heading driven along the hanging wall contact. Each mined drift is filled with cemented sand fill ... providing back support for the next drift.

• Post Pillar– Hybrid between room and pillar and cut and fill– moderately thick, flat, tabular ore bodies – moderate to low strength back

Underhand Cut and FillUnderhand Cut and Fill

Underhand cut-and-fill

•Weak, narrow vein orebodies

•Cemented backfill required

Post Pillar Cut and FillPost Pillar Cut and Fill

ShrinkageShrinkage

•• Ore is broken in horizontal slices working Ore is broken in horizontal slices working upwards.upwards.

•• Sufficient ore withdrawn at the bottom Sufficient ore withdrawn at the bottom after each slice to accommodate swell after each slice to accommodate swell (30% (30% -- 40%)40%)

•• Remainder stays in the Remainder stays in the stopestope to provide a to provide a working platform ... removed at the end.working platform ... removed at the end.

•• StopesStopes separated by intermediate separated by intermediate (recoverable) pillars (recoverable) pillars

ShrinkageShrinkage

•• orebodyorebody width 1.2m width 1.2m -- 30m30m•• tabular tabular orebodyorebody; regular boundaries; regular boundaries•• dip >50dip >50°°•• stable hanging wall and footwallstable hanging wall and footwall•• uniform draw down importantuniform draw down important•• dilution generally lowdilution generally low•• Ore must be unaffected by storage in Ore must be unaffected by storage in stopestope•• Labour intensive method, limited scope for Labour intensive method, limited scope for

mechanization mechanization

ShrinkageShrinkage

ShrinkageShrinkage

ShrinkageShrinkage•• Summary of ApplicationSummary of Application……

–– Shrinkage not a common method ... too labour intensiveShrinkage not a common method ... too labour intensive–– Employed only where mechanization not possible.Employed only where mechanization not possible.–– Maintaining Maintaining stopestope full of muck increases possible full of muck increases possible stopestope spans and minimizes dilution spans and minimizes dilution

.. support and development costs reduced... support and development costs reduced.–– Limited production capacity and bulk of ore tied up for a long tLimited production capacity and bulk of ore tied up for a long time.ime.

•• AdvantagesAdvantages……–– moderate production rate. moderate production rate. –– draw down by gravitydraw down by gravity–– conceptually simple (small mine usage)conceptually simple (small mine usage)–– low capital investmentlow capital investment–– minimal support in minimal support in stopestope–– moderate development moderate development –– good recovery, low dilution good recovery, low dilution

•• DisadvantagesDisadvantages……–– low productivity low productivity –– moderate to high mining cost.moderate to high mining cost.–– laborlabor--intensiveintensive–– dangerous working conditionsdangerous working conditions–– ore tied up in ore tied up in stopestope–– ore subject to oxidation, packing in ore subject to oxidation, packing in stopestope

Shrinkage Variation Shrinkage Variation -- Raise or Raise or AlimakAlimak MiningMining

•• A variation of shrinkage miningA variation of shrinkage mining•• Long hole drill is mounted on an Long hole drill is mounted on an alimakalimak

raise climberraise climber•• Mechanized, cost effective methodMechanized, cost effective method

AlimakAlimak MiningMining

AlimakAlimakMiningMining

Raise or Raise or AlimakAlimak MiningMining







Raise bore and Box hole MiningRaise bore and Box hole Mining

•• Summary of applicationSummary of application–– Raise bore holes are excavated and filled.Raise bore holes are excavated and filled.–– Can be used to mine tabular narrow steeply dipping deposits Can be used to mine tabular narrow steeply dipping deposits

or moderately thick flat deposits.or moderately thick flat deposits.–– Low to high strength oreLow to high strength ore–– None entryNone entry–– Requires very high grade ore as method is very expensiveRequires very high grade ore as method is very expensive

•• AdvantagesAdvantages……–– Very safeVery safe–– Low dilutionLow dilution–– High recoveryHigh recovery–– Miners not exposed to environmental Miners not exposed to environmental hazzardshazzards

•• DisadvantagesDisadvantages……–– Very expensiveVery expensive–– Low production ratesLow production rates

Raise Bore MiningRaise Bore Mining

Raise Bore Raise Bore MiningMining

Raise Bore ChamberRaise Bore Chamber

Extraction ChamberExtraction Chamber

Box hole Box hole MiningMining

Raise Bore MiningRaise Bore Mining

Hard Rock Bulk Mining MethodsHard Rock Bulk Mining Methods

•• Sublevel / Sublevel / BlastholeBlasthole / Long Hole/ Long Hole•• Vertical Crater Retreat (VCR)Vertical Crater Retreat (VCR)•• AvocaAvoca•• Sublevel Caving Sublevel Caving •• Block CavingBlock Caving

Sublevel Sublevel StopingStoping Methods Methods •• Sublevel Sublevel stopingstoping is also known as "is also known as "blastholeblasthole stopingstoping" or " or

""longholelonghole stopingstoping".".•• vertical or steeply dipping ore bodies with regular boundariesvertical or steeply dipping ore bodies with regular boundaries•• mined from levels at predetermined vertical intervalsmined from levels at predetermined vertical intervals•• drilling/blasting from sublevels (drilling/blasting from sublevels (overcutovercut or undercut), mucking or undercut), mucking

from undercutfrom undercut•• ore pillars between ore pillars between stopesstopes for support, may be recovered later for support, may be recovered later •• The The orebodyorebody is divided into sections up to 100 m high and is divided into sections up to 100 m high and

further divided laterally into alternating further divided laterally into alternating stopesstopes and pillars. A and pillars. A main haulage drive is created in the footwall at the bottom, main haulage drive is created in the footwall at the bottom, with cutwith cut--outs for drawouts for draw--points connected to the points connected to the stopesstopes..

•• Long hole Long hole blastholeblasthole and and stopingstoping uses longer and larger uses longer and larger diameter diameter blastholesblastholes than sublevel than sublevel stopingstoping, thus requiring less , thus requiring less drilling than sublevel drilling than sublevel stopingstoping. Greater drilling accuracy is . Greater drilling accuracy is requiredrequired

Sublevel Sublevel StopingStoping MethodsMethods•• minimum minimum orebodyorebody width 2mwidth 2m•• tabular or massive shape tabular or massive shape •• Can be mined transverse or longitudinalCan be mined transverse or longitudinal•• dip >50dip >50°°•• large large stopesstopes (non(non--entry)entry)•• limited selectivity, limited selectivity, orebodyorebody should be regularshould be regular•• No BackfillNo Backfill

–– pillar size considerations similar to room and pillarpillar size considerations similar to room and pillar–– competent footwall, ore zone and hanging wallcompetent footwall, ore zone and hanging wall–– dilution a potential problemdilution a potential problem

•• With BackfillWith Backfill–– pillar size must be suitable for recoverypillar size must be suitable for recovery–– stress on pillars should be lowstress on pillars should be low–– fill material must allow recovery of pillars with minimum dilutifill material must allow recovery of pillars with minimum dilution on

Sublevel Sublevel StopingStopingMethodsMethods

Sublevel Sublevel StopingStoping MethodsMethods






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SLOS Primary/Secondary with Transverse SLOS Primary/Secondary with Transverse Drilling and ExtractionDrilling and Extraction





Block PlanBlock Plan


•• Summary of ApplicationSummary of Application……–– method became popular after development of large diesel method became popular after development of large diesel

LHDLHD’’ss in the last 40 yearsin the last 40 years–– efficient in drilling, blasting and loadingefficient in drilling, blasting and loading–– high utilization of mechanized equipmenthigh utilization of mechanized equipment–– limited selectivity with irregular limited selectivity with irregular orebodiesorebodies

•• AdvantagesAdvantages–– good productivitygood productivity–– moderate costmoderate cost–– amenable to mechanizationamenable to mechanization–– safe operating conditionssafe operating conditions–– good recovery; moderate dilution good recovery; moderate dilution

•• DisadvantagesDisadvantages……–– Expensive initial developmentExpensive initial development–– inflexible / noninflexible / non--selective selective

AvocaAvoca

• Allows mining of narrow ore zones with high recovery.

• Requires stope development with upper and lower drill drifts, similar to longhole mining.

• Stope is backfilled with waste rock from the upper drill horizon ... no pillars required.

Advantages…– Flexibility– no requirement for pillars– waste storage with short haulage

• Disadvantages– higher dilution– advance limited by backfill availability must have two

accesses

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AvocaAvoca

AvocaAvoca

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AvocaAvoca

Vertical Crater Retreat / VCRVertical Crater Retreat / VCR

• Very similar to Sub level stoping.• Employs a unique blasting technique called

the crater blasting • Also resembles Shrinkage stoping as ore is

extracted in horizontal slices.• The ore is recovered from an undercut

drawpoint system resembling that used in sublevel open stoping

• Can be used in steeply dipping ore bodies under the same conditions as sub level stoping and shrinkage stoping

• Blasted ore remains in the stope and is used to support the hanging wall

Vertical Crater Retreat / Vertical Crater Retreat / VCRVCR

Vertical Crater Retreat / VCRVertical Crater Retreat / VCR

• Advantages– VCR is a bulk, high-capacity mining method with good

recoveries;– It is an efficient stoping method that is very susceptible to

mechanization and can have productivities in excess of 32 tonnes/employee-shift;

– It offers good wall support during the stoping phase by using shrinkage techniques;

– It is a safe method with miners working under a fully supported back that can be adequately ventilated.

• Disadvantages– VCR requires extensive diamond drilling, pre-stope planning,

and development lead-time for maximum effectiveness;– Ore is tied up in the stope until final drawdown ... representing

lost income;– Some ores are mineralogically unstable and may be subject to

breakdown, causing problems with benefaction, drawing, etc..– High concentration of explosive and hole deviation may damage

walls and may increase dilution problems

Sublevel CavingSublevel Caving•• The The orebodyorebody is divided into closely spaced vertical is divided into closely spaced vertical

sublevels. From each sublevel the sublevels. From each sublevel the orebodyorebody is developed is developed by a series of drifts from by a series of drifts from hangingwallhangingwall to footwall to to footwall to lateral extremity on strikelateral extremity on strike

•• From the sublevel drifts the ore immediately above is From the sublevel drifts the ore immediately above is drilled with drilled with longholeslongholes in a fan shape patternin a fan shape pattern

•• size should be large enough to allow for sufficient size should be large enough to allow for sufficient vertical subvertical sub--levels for lateral and vertical interactionlevels for lateral and vertical interaction

•• massive and/or tabular and steep, uniform shapemassive and/or tabular and steep, uniform shape•• steeply dipping >50 degrees unless massivesteeply dipping >50 degrees unless massive•• competent ore with a waste competent ore with a waste hangingwallhangingwall that can cave. that can cave.

Stable footwall for development access.Stable footwall for development access.•• high dilution, very sensitive to poor fragmentationhigh dilution, very sensitive to poor fragmentation•• limited selectivitylimited selectivity•• surface conditions must allow for subsidence Sublevel surface conditions must allow for subsidence Sublevel

caving is usually carried out underneath an open pit caving is usually carried out underneath an open pit when it becomes uneconomic to mine from the pit when it becomes uneconomic to mine from the pit

Sublevel CavingSublevel Caving

Sublevel CavingSublevel Caving

Sublevel CaveSublevel Cave

Sublevel CavingSublevel Caving•• Summary of ApplicationSummary of Application……–– LongholeLonghole drilling is performed in a fan shaped pattern that radiates upwdrilling is performed in a fan shaped pattern that radiates upwards from sublevel ards from sublevel

drift. drift. –– Ore is mucked from the sublevel drift, transported and dumped inOre is mucked from the sublevel drift, transported and dumped into to orepassesorepasses by by LHD'sLHD's. . –– Production drilling and loading are carried out on separate leveProduction drilling and loading are carried out on separate levels and are independent of ls and are independent of

each othereach other–– many work faces result due to the large number of drift facesmany work faces result due to the large number of drift faces–– ore is blasted against a caved face therefore explosive consumptore is blasted against a caved face therefore explosive consumption is high ion is high

•• AdvantagesAdvantages……–– high productivity ratehigh productivity rate–– many work faces and efficientmany work faces and efficient–– highly mechanizedhighly mechanized–– safe method as nonsafe method as non--entry entry

•• DisadvantagesDisadvantages……–– high dilutionhigh dilution–– surface subsidence resultssurface subsidence results–– potential for high ore losses potential for high ore losses -- low recoverylow recovery–– explosive consumption high (choke blasting)explosive consumption high (choke blasting)–– high development costshigh development costs–– hi intensity of drill and blast required in order to generate a hi intensity of drill and blast required in order to generate a mobile granular ore within a mobile granular ore within a

cave mediumcave medium

Block CavingBlock Caving

•• Block caving is applicable to large, deep, lowBlock caving is applicable to large, deep, low--grade deposits.grade deposits.

•• It is often done to continue mining after open pit It is often done to continue mining after open pit mining becomes uneconomic or impossible. mining becomes uneconomic or impossible. However, some mines start as block cave However, some mines start as block cave operations. operations.

•• A grid of tunnels is driven under the A grid of tunnels is driven under the orebodyorebody. . The rock mass is then undercut by blasting. The rock mass is then undercut by blasting. Ideally the rock will break under its own weight. Ideally the rock will break under its own weight.

•• Broken ore is then taken from draw points. Broken ore is then taken from draw points. There may be hundreds of draw points in a There may be hundreds of draw points in a large block cave operation (Figure 3).large block cave operation (Figure 3).


•• orebodyorebody and and hangingwallhangingwall must cave therefore the ore must cave therefore the ore must have sufficient plan area to initiate cave through must have sufficient plan area to initiate cave through the undercut (>1000m2). Vertical dimension generally the undercut (>1000m2). Vertical dimension generally greater .greater .

•• massive and/or tabular and steep, uniform shapemassive and/or tabular and steep, uniform shape•• steeply dipping >50 degrees unless massive which then steeply dipping >50 degrees unless massive which then

requires a high vertical dimensionrequires a high vertical dimension•• orebodyorebody and and hangingwallhangingwall must be weak and must be weak and cavablecavable. .

Otherwise the undercut area must be large and Otherwise the undercut area must be large and consequently fragmentation is large.consequently fragmentation is large.

•• high dilution, very sensitive to poor fragmentationhigh dilution, very sensitive to poor fragmentation•• no selectivityno selectivity•• surface conditions must allow for subsidence surface conditions must allow for subsidence





Block CavingBlock Caving•• Summary of applicationSummary of application……

–– upon completion of the undercut the ore falls down finger raisesupon completion of the undercut the ore falls down finger raises or cones or cones and is a continuous process as material is removed at the draw land is a continuous process as material is removed at the draw levelevel

–– theoretically no production drilling is required. In practise, ltheoretically no production drilling is required. In practise, long holes are ong holes are drilled widely spaced to induce fracturing, secondary drilling odrilled widely spaced to induce fracturing, secondary drilling of oversize f oversize rock is a frequent operation.rock is a frequent operation.

–– ore handling in track mining utilizes gravity forces to deliver ore handling in track mining utilizes gravity forces to deliver material to material to rail cars. However, chutes require small fine fragmentation and rail cars. However, chutes require small fine fragmentation and grizzly is grizzly is very labour intensive and is generally a bottleneck in the produvery labour intensive and is generally a bottleneck in the production ction cycle. cycle.

–– Ore handling in trackless mining is through Ore handling in trackless mining is through drawpointdrawpoint mucking and the mucking and the development work required is substantially reduced since no grizdevelopment work required is substantially reduced since no grizzly level zly level or raises.or raises.

–– Rule of thumb: for an Rule of thumb: for an orebodyorebody to be to be cavablecavable approximately 50% of the approximately 50% of the ore fragments should break to 1.5m or less in maximum dimension.ore fragments should break to 1.5m or less in maximum dimension. One One can't have large arches formed since will result in an air blastcan't have large arches formed since will result in an air blast/or high /or high stresses in the abutments. stresses in the abutments.

Block CavingBlock Caving•• AdvantagesAdvantages……

–– highest production rate of any underground mining methodhighest production rate of any underground mining method–– lowest operating cost of any underground mining methodlowest operating cost of any underground mining method–– production (not development) is entirely by caving production (not development) is entirely by caving ieie. No drill or blast . No drill or blast

other than secondary blastingother than secondary blasting–– ability to be highly mechanized ability to be highly mechanized

•• DisadvantagesDisadvantages……–– caving and subsidence occur on large scalecaving and subsidence occur on large scale–– high dilutionhigh dilution–– draw control is critical to success of methoddraw control is critical to success of method–– slow and extensive development requirementsslow and extensive development requirements–– high support costshigh support costs–– caving and fragmentation is extremely difficult to predict or cocaving and fragmentation is extremely difficult to predict or controlntrol–– inflexible methodinflexible method-- no selectivityno selectivity–– possible ore oxidation if caving/drawing is slow possible ore oxidation if caving/drawing is slow

Mining EquipmentMining Equipment

DrillingDrilling

DrillingDrilling

Drilling Equipment Drilling Equipment -- JacklegJackleg

Drill Drill –– Development JumboDevelopment Jumbo

Drill Drill –– Development JumboDevelopment Jumbo

Drill Drill –– Development Development JumboJumbo

Drill Drill –– longholelonghole –– ITHITH

Drill Drill –– LongholeLonghole -- ITHITH

Drill Drill –– LongholeLonghole --TophammerTophammer

Drill Drill –– LongholeLonghole -- TophammerTophammer

Drill Drill –– LongholeLonghole -- TophammerTophammer

Drill Drill –– Raise bore rotary drillRaise bore rotary drill

Drill Drill –– Raise bore rotary drillRaise bore rotary drill

Raisebore Station and Reamer Bit

Mucking Mucking Equipment Equipment --

CavoCavo

Mucking Equipment Mucking Equipment -- CavoCavo

Mucking Equipment Mucking Equipment –– LHD with 11 LHD with 11 mm33 bucketbucket

MuchingMuching Equipment Equipment –– Remote Remote Control ScoopControl Scoop

Mucking Equipment Mucking Equipment –– 15 15 tonnetonneTruckTruck


Mucking Equipment Mucking Equipment –– LHD LHD loading Truckloading Truck


Mucking Equipment Mucking Equipment –– 50 50 tonnetonne TruckTruck

Mucking Equipment Mucking Equipment –– U/G ore trainU/G ore train

HardrockHardrock Mining Method SelectionMining Method Selection

Nicolas Method Identify key factors that determine mining methodRank each of the factors for different methodsApply all factors to an orebodyOrebody with the highest rating is the optimum mining

method












•• SOFTROCK MININGSOFTROCK MINING–– PotashPotash–– CoalCoal

Potash MiningPotash Mining

• Long room-and-pillar mining method. Ore is mined from rooms in three passes, separated by pillars supporting the overlying strata.

• Automated Marietta continuous miners are capable of extracting up to 650t/h of ore.

• The run-of-mine ore is loaded on to extensible conveyors attached to the continuous miners. These connect to the main haulage conveyors, which move the ore to skip-loading pockets at the shafts, where it is hoisted to surface.

Long Wall MiningLong Wall Mining• Highly mechanized underground mining system for

mining coal. • A layer of coal is selected and blocked out into an

area known as a panel. • A typical panel might be 3000 m long by 250 m wide. • Passageways areexcavated along the length of the

panel to provide access and to place a conveying system to transport material out of the mine.

• Entry tunnels are constructed from the passageways along the width of the panel. The longwall system mines between entry tunnels.

• Extraction is an almost continuous operation involving the use of self-advancing hydraulic roof supports sometimes called shields, a shearing machine, and a conveyor which runs parallel to the face being mined.

LongwallLongwall MiningMining

Long Wall MiningLong Wall Mining




Soft Rock Room and Pillar EquipmentSoft Rock Room and Pillar Equipment



Underground Underground SoftrockSoftrock MiningMining

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