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VENTILATION SYSTEM DESIGN VENTILATION SYSTEM DESIGN AND COMPUTER SIMULATION AND COMPUTER SIMULATION

FOR AN UNDERGROUND METAL MINEFOR AN UNDERGROUND METAL MINE

Presented by Presented by

Hongliang (Henry) WangHongliang (Henry) Wang

Newmont USA LimitedNewmont USA Limited

SME 2011

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Table of ContentsTable of Contents

1. Introduction: Exodus Project1. Introduction: Exodus Project

2. Review of Newmont2. Review of Newmont’’s Nevada Underground s Nevada Underground Mines and Mine Ventilation SystemsMines and Mine Ventilation Systems

3. Ventilation System Design and Optimization for 3. Ventilation System Design and Optimization for Exodus ProjectExodus Project

4. Ventilation Simulation4. Ventilation Simulation

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1.1. Introduction: Exodus Project Introduction: Exodus Project

EXODUS UG Project

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4

North LanternPit

Lantern 3 Pit Push Back

New Portal

Ventilation Drift

OldPortal

Lantern Open PitsLantern Open Pits

Exodus Underground ProjectExodus Underground Project

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Exodus Deposit: Surface ExplorationExodus Deposit: Surface Exploration

Lantern 3 Pit

Exodus Deposit

Old Lantern Pit

Inferred Resource:800K Oz; 0.25 Oz/ton;1000-1700 ft below surface.

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Exodus Deposit: Underground ExplorationExodus Deposit: Underground Exploration

Exodus 0.1 Ore Shapes: Steeply Dipping

Exploration Drift: 6000 ft

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Exodus Project in 2010:Exodus Project in 2010:Continue exploration, start mine development, bring to Continue exploration, start mine development, bring to

production in Q4; production in Q4; and deal with surface mining…

Lantern 3 Pit: 2009~2010

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Mine Designs of Exodus ProjectMine Designs of Exodus Project

Block model evaluation;Block model evaluation;

Mining methods selection, stope designs;Mining methods selection, stope designs;

Mine ventilation designs;Mine ventilation designs;

Material handling study;Material handling study;

CutCut--off grade and cost analysis;off grade and cost analysis;

Mine design optimization;Mine design optimization;

redesign with updated block model; redesign with updated block model; ……

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Mine ventilation designsMine ventilation designs

Ventilation for different Stages of Mine Life: Ventilation for different Stages of Mine Life: Exploration, Development, PreExploration, Development, Pre--production, upper level ventilation, production, upper level ventilation, lower level ventilation, future growth;lower level ventilation, future growth;

Ventilation System Selection:Ventilation System Selection:Exhausting vs. Forcing, Shaft vs. RampingExhausting vs. Forcing, Shaft vs. Ramping

Scheduling and sequencing of vent infrastructures:Scheduling and sequencing of vent infrastructures:Ahead of vs. parallel with production;Ahead of vs. parallel with production;Long vent raise vs. short vent raises in series;Long vent raise vs. short vent raises in series;

Surface Mining:Surface Mining:Ramp,Ramp, vent raises and escapeways to the active pit;vent raises and escapeways to the active pit;

Computer Simulation and ventilating design optimization.Computer Simulation and ventilating design optimization.

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2. Nevada Underground Mines Ventilation System Review2. Nevada Underground Mines Ventilation System Review

Mine SiteMine SiteAnnual Annual ProductionProduction Ventilation Ventilation

SystemSystem Total CFMTotal CFM Main Fan HPMain Fan HP

LEEVILLELEEVILLE(Shaft Mining)(Shaft Mining)

~1,5 M Tons; ~1,5 M Tons; 500,000 Oz.500,000 Oz.

BoosterBooster 1.2~1.4 M1.2~1.4 M 2 x 2K (parallel)2 x 2K (parallel)

MIDASMIDAS 360,000 tons;360,000 tons;180,000 Oz.180,000 Oz.

Push PullPush Pull ~1.0M~1.0M Intake: 2 x 250Intake: 2 x 250Exhaust: 3 x Exhaust: 3 x 250+ 125250+ 125

DEEP POSTDEEP POST(Closed)(Closed)

600,000 Tons;600,000 Tons;350,000 Oz.350,000 Oz.

Push PullPush Pull ~800K~800K Intake: 2 x 500Intake: 2 x 500Exhaust: 2x450Exhaust: 2x450

CHUKARCHUKAR(Temporally (Temporally closed)closed)

400,000 Tons;400,000 Tons;80,000 Oz.80,000 Oz.

ExhaustingExhausting ~250K~250K 3 x 250 (in 3 x 250 (in series)series)

EXODUSEXODUS 430,000 Tons;430,000 Tons;108,000 Oz108,000 Oz

ExhaustingExhausting 400K (designed)400K (designed) 500500

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•• LeevilleLeeville

Production Shaft Ventilation Shaft

DPM Compliance:Bio-diesel, new engines,Electric haul trucks…

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Leeville Main FanLeeville Main Fan

2M HP, 700 KCFM

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Greater LeevilleGreater Leeville

Φ 26’~32’ 2100’ deep2.2 MCFM, ~$100M

NEW VENT SHAFT

Production Shaft

Ventilation Shaft

County Road

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•• MidasMidasNEW DEEPINTAKE RAISEΦ12, 1200’

Main DeclineEXHAUST RAISE

EXHAUST RAISE

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•• Chukar Chukar

NEW DECLINE

OLD DECLINE

Original Mine Designs:Two years mine life; three250 HP fan in series.

Mine Life Extension

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•• Deep PostDeep Post

Barrick’s Post Betze Pit

Exhaust Raises

Intake Raises

Main Fans

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Short Summary of the ReviewShort Summary of the Review

Ventilation systems are very expensive, capital and Ventilation systems are very expensive, capital and operating cost are high; ventilation system is difficult to set operating cost are high; ventilation system is difficult to set up or upgrade.up or upgrade.

““Over ventilated ?Over ventilated ?”” not the case in most mines, where not the case in most mines, where operations are fighting hard for ventilation due to poor operations are fighting hard for ventilation due to poor efficiency of fresh air distribution. Ventilation management efficiency of fresh air distribution. Ventilation management plan is critical for mine operations.plan is critical for mine operations.

New DPM regulation adds more challenges to mine New DPM regulation adds more challenges to mine operations, but ventilation improvement is often the ultimate operations, but ventilation improvement is often the ultimate solution.solution.

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Lantern 3 Pit: 2010~2011

3. Exodus Project 3. Exodus Project Mine Ventilation Design Options and Economic AnalysisMine Ventilation Design Options and Economic Analysis

North Lantern

Pit

Decline

Q2: How many reserves we can generate?Q2: How many reserves we can generate?2010MY Model total resource: 2010MY Model total resource: 800,000 ounces; average grade @ 0.25; 800,000 ounces; average grade @ 0.25;

Q1: What is the best way to design the mine?There might be 16 different scenarios: Cut-off grade (Oz/ton): 0.15, 0.18, 0.20, 0.22;Stope width (ft): 15, 20, 25, 30.

Q3: What are the options for ventilation?Q3: What are the options for ventilation?How much air we need, what is the best way How much air we need, what is the best way to establish the vent system so we can start production in Q4? to establish the vent system so we can start production in Q4?

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Stope Design and OptimizationStope Design and Optimization

1

3

2

4

2

3 4

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Mine Ventilation Design Option 1: Deep Vent RaiseMine Ventilation Design Option 1: Deep Vent Raise

NPV with 0.2 cutoff designs:

1600 ft; Φ14~16ft400 KCFM, 3000 FPMEstimated cost: $3~5M

-$6.5M

@ $950 gold price, 10% discount rate

Mining from Bottom Up

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Mine Ventilation Design Option 2: Dual DeclineMine Ventilation Design Option 2: Dual Decline

Dual Decline:~10,000 ft, 16’X16’, $11M,

$45KNPV with 0.2 cutoff designs:

@ $950 gold price, 10% discount rate

Mining from Multiple Levels

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Mine Ventilation Design Option 3: Vent Decline + Short Vent RaisMine Ventilation Design Option 3: Vent Decline + Short Vent Raiseses

Vent Decline: 1400 ft, $1.5MMain Fan

Vent Raises:Φ 12~14ft;~$500,00

NPV with 0.2 cutoff designs: $3.1M

@ $950 gold price, 10% discount rate

Mining from Multiple Levels

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TonnageTonnage--Grade Curve of the Block Model: Upside PotentialsGrade Curve of the Block Model: Upside PotentialsExodus Grade-Tonnage Curve (Design Shapes)

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

0.00 0.05 0.10 0.15 0.20 0.25 0.30

Cutoff Grade

Tons

and

Oun

ces

0.000

0.050

0.100

0.150

0.200

0.250

0.300

0.350

0.400

Head

Gra

de (o

z/to

n)

TONS OUNCES GRADE

Case Tons Grade Ounces NPVBase Case @900 1,273,114 0.247 314,479 11,015,807$

Base Case @1100 1,273,114 0.247 314,479 44,646,905$ 0.18 Cutoff @1100 1,235,256 0.224 277,188 25,510,228$ 0.22 Cutoff @1100 561,051 0.265 148,846 16,310,246$

Base Case @950 1,273,114 0.247 314,479 17,785,952$ 0.18 Cutoff @950 1,235,256 0.224 277,188 2,876,978$ 0.22 Cutoff @950 561,051 0.265 148,846 3,493,655$

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Mine Ventilation System Selection: Literature Review Mine Ventilation System Selection: Literature Review

(b) And the following arguments favor a forcing system [1, 2].

• Deliver fresh air to working places, which is desirable for mine ventilation quality control. In exhausting system, intake air gets contaminated by underground traffic.

• Working places are independent of each other. In exhausting system, lower levels get experienced air from top levels.

Based on the location of the main fan(s) in the system.

(a) The following arguments favor an exhaust system [1, 2].

• Utilize haulage or hoisting openings as intakes, which is desirable for mine operations. In forcing system, main haulage route is in exhaust air.

• In case of fire or emergency, the primary escape way is in intake air (depended on the location of fire). In forcing system, the secondary escape way is in fresh air.

[1] Mine ventilation and air conditioning. Howard L. Hartman.[2] Engineering factors in the ventilation of metal mines. G. E. McElroy.

WorkingArea

WorkingArea

Haul R

oad

WorkingArea

Haul R

oad

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Exhausting or Forcing?Exhausting or Forcing?

Main Fan

Haul Road

If the depositgrows significantly

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CFM RequirementCFM RequirementEquipment List and CFM requirements @Equipment List and CFM requirements @150 CFM/HP150 CFM/HP

Equipment Type HP*Utilization

RateCFM

RequirementJumbo 92 80% 11,040Jumbo 139 80% 16,680

Explosive Truck 80 80% 9,600Forklift 116 80% 13,920Forklift 116 80% 13,920Loader 250 80% 30,000Loader 250 80% 30,000

Haul Truck 409 80% 49,080Haul Truck 410 80% 49,200Haul Truck 411 80% 49,320

Shotcrete Spray Truck 149 80% 17,880Service/Lube Truck 117 80% 14,040

Bolter 154 80% 18,480Bolter 155 80% 18,600

Other Desiel Equipments 200 80% 24,000Total 3048 365,760

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Main Fans: 102Main Fans: 102”” 500HP500HP

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ChallengesChallengesReserve Uncertainties: Reserve Uncertainties:

only top half of the deposit was in only top half of the deposit was in ‘‘reservereserve’’ quality.quality.Ground Condition Uncertainties:Ground Condition Uncertainties:

lack of Geotech information for the locations of the vent raiseslack of Geotech information for the locations of the vent raises..

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••NevadaNevada’’s weather: summers weather: summer

ChallengesChallenges

••NevadaNevada’’s weather: winters weather: winter

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4. Ventilation Simulation4. Ventilation Simulation

Courtesy of “Mine ventilation and air conditioning”, Howard L. Hartman.

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Main Fan Performance:415 KCFM, 6.5” H2O;485 HP;Annual opt cost: $350,000.

Dual Vent Raises:Φ 10’, 250’,

Short Vent RaisesΦ12’, 75’,

Surface

0.1 Ore Shape

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Main Fan Setting

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300 ft

Surface Blasting vs. Underground VentilationSurface Blasting vs. Underground Ventilation

CurrentBench

Surface Blasting vs. Underground VentilationSurface Blasting vs. Underground Ventilation

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Questions ?Questions ?