New Liberty Project - AVESORO · –Pit design and optimisation –Calculation of Reserves ......

Aureus Mining New Liberty Project

Mining

February 2014

Contents

• Geotechnical

• Pit optimisation

• Pit design

• Mining Contractor

• Groundwater management

• Water management

AMC input on: – Updated Geotechnical assessment – Pit design and optimisation – Calculation of Reserves – Development of High level production schedules – Design of ROM Pad – Design and sequencing of Waste Rock Dumps

• RPS Aquaterra input on: – Surface water assessment and pumping recommendations – Pumping tests on monitoring boreholes – Groundwater assessment and – Development of groundwater model

• Knight Piesold input on:

– Geotechnical stability of areas under TSF, WRD, MC Dams

Geotechnical, Mine design and Water management support

3

New Liberty: Mining Schedule Highlights

• Updated geotechnical model and slope design

• Production evenly distributed over LOM – mining design has a high level of confidence

• Reserves contained within open pit at depths of 180-220m below surface

• WRD wraps around pit and backfill into Larjor pit

• Annual waste mining rate of 25Mt for four years using mining contractor

LOM Production and Grade

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0

20

40

60

80

100

120

140

Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8

Production + Inferred (koz)Production (koz) - LHSHead Grade (g/t) - RHS

4

Key Mining Points

• In situ reserves of 924koz gold at 3.4g/t (contained in 8.5mt)

• Pit is 2km long, 420m wide and 220m deep

• Mine life = 8 years

• Total ore mined = 8.5Mt

• Total mined tonnage = 140Mt

• Stripping ratio = 15.5:1

• Mining cost $3.06/t mined*

• Gold produced = 859koz

5

W

E

* Includes cost of fleet

Experienced Mining Contractor: Banlaw Africa Ltd.

• Combined executive management experience of over 50 years in similar West African environments

• Mining at Bonikro gold mine (Newcrest) in Cote d’Ivoire

• Experience on various projects in Ghana (Gold Fields), Burkina Faso (High River, Bissa), Cote d’Ivoire (Endeavour, Agbaou) and the DRC (Banro, Twangiza)

• Banlaw’s management team are well known to the Aureus management & project team

Mining Contract

• Developed from the detailed AMC mine plan

• All-in cost includes establishment & mobilisation, load & haul, drill & blast, pre-split, RC grade control and fixed costs for the life of mine

• New mining fleet agreed

6

Material Movement by Stage

-

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

Year 0 Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8

Ton

ne

s (M

t)

Material Movement by Stage

Stage 1 Stage 2 Stage 3 Stage 4 Stage 5

Larjor

Marvoe

Latiff Kinjor

2 4 3 1

5 7

Mining •2 km long open pit operation, 220m deep

•Staged mining sequence planned

•High grade (3.4g/t) allows for lower throughput, hence smaller plant – 1.1Mtpa

Ore Production

-

1.0

2.0

3.0

4.0

5.0

6.0

0.0

0.1

0.1

0.2

0.2

0.3

0.3

0.4

0.4

0.5

Year 0 Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8

Min

ed O

re G

rade

(Au

g/t)

Min

ed T

onne

s (M

t)

Mined Ore Tonnes and Grade

Mined Ore Tonnes Mined Grade (g/t) Mined Grade (g/t) FS

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Waste mining and strip ratio

9

-

10.0

20.0

30.0

40.0

50.0

60.0

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

Year 0 Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8

Strip

Rat

io

Min

ed T

onne

s (M

t)

Mined Tonnes and Strip Ratio

Mined Waste Tonnes Mined Ore Tonnes Strip Ratio

Ounces Produced

-

100

200

300

400

500

600

700

800

900

1,000

0

5

10

15

20

25

30

35

40

45

Year 0 Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8

Cum

ulat

ive

Oun

ces

Prod

uced

(koz

)

Oun

ces

Prod

uced

(koz

)

Ounces Produced and Cumulative Ounces Produced

Gold Produced (Au oz) Gold Produced (Au oz) FS

Cumulative Ounces Produced FS Cumulative Ounces Produced

10

Cash flows and revenues

11

-

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

Year 0 Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Year 7 Year 8

Cos

t per

Ton

ne M

ined

($ m

illio

ns/t)

Min

ing

Cos

t (U

S$M

)

Mining Cost and Cost Per Tonne Mined

Total Mining Cost Cost Per Tonne Mined

Aim

• Define mineralisation boundaries and minimise

dilution

• Define mining blocks

Prior to mining

• RC drill programme on 15x15m grid planned

• Drill 1 year’s production in advance, ~ 8,000m/ year

• Reconcile with orebody block model (based on a

30x30m grid)

• Establish detailed distribution of gold and incorporate into mine planning 12

Grade Control

Production

• RC drilling in dry season in advance of mining

• Sample blastholes (10m benches)

• In pit geological mapping – structures, bleaching, silicification, sulphides, mag sus.

• Reconciliation of grade control work with both orebody model and plant figures

• Marking out of grade blocks (minimum mining width of 2.5m)

• Blast design to separate waste from ore

• Selective mining - 2.5m flitches on 10m benches

• Blending on ROM pad near crusher to ensure steady feed to plant

• High, Medium & Low grade stockpiles and Mineralised waste 13

Grade Control

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Waste Rock Dumps

• The WRD is a wrap-around dump between 30-40m high

• Protection provided below the MCDC dams – placing a barrier between the dams and the pit

• Dumps are flat and cheaper to construct

• Flatter dumps will be easier to rehabilitate and will be visually less obtrusive

• Dumps will help to limit the inflow of surface water into the pit during the rainy season

• Drainage on the dumps will be managed

FS Nov 2012 Waste Dump located to south of Pit

End of Pre-strip (Year 0)

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Construction of; haul roads, perimeter safety bund/road.

ROM Pad built up to crusher level Skyway built.

Construction of; Larjor drainage channels. Latkin drainage channel.

Construction of; culverts and flood-ways, permeable bund locations.

End of Year 1 Mining

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North, South East and East Dump built up to control surface run-off

Priority dumping in North and North West Dump reduce haulage distances.

Low-grade stockpile area to be built up to pad level with oxide. The oxide can be reclaimed for capping TSF at end-of-mine.

Waste Dump abuts dam walls.

Outcomes/ Conclusions: • No significant geotechnical risks highlighted • Quality of geotechnical database improved • Improved confidence in the geotechnical model and in slope designs • Likelihood of toppling failure is considered low • Satisfactory Factors of Safety achieved in the calculated slopes • 15m geotechnical berm introduced as additional safety measure • Slope design parameters outcomes:

– Bench face angle 70⁰ & 75⁰ (steepened from 65⁰ in Feasibility study) – Overall slope angle 48⁰ (broadly similar to Feasibility Study) – Local areas of slope de-watering recommended

Geotechnical Data Work completed in 2013

Work undertaken: • New data acquired

– Campaign of targeted drilling into interpreted geological structures (7 holes) – Detailed geotechnical surveys on selected holes (20 holes)

• Structural model of pit updated & 8 domains defined

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Water Management – work completed

• Predominantly rainfall dominated system: Rainfall seasonal with wet season

from July - September. Dewatering system designed to

minimize pit days following storm events

• Surface water management updated based on new waste dump and infrastructure

• Storm event pit inflows revised based on new designs.

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Water Management

• Waste rock dump designed to minimize pit inflows • Dumps profiled to drain water away from pit catchment

• All flows within pit catchment dealt with by in-pit pumps

• Main discharge channel and sedimentation basin developed by optimizing natural drainage to south

• Groundwater investigation completed

• Numerical groundwater flow model developed

• Groundwater pit inflows updated

• Groundwater drawdown updated

• Staged dewatering strategy and design

• Depressurization modelling completed

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20

Final Pit Number of Sykes HH220i Pumps

Sump Pumps Transfer Station Pumps

Larjor High Head Pump or inclined dewatering bore(s) used following backfill of Larjor Pit

Latiff 1 5

Kinjor 1

Marvoe 1 1

NB One extra sump pump will be required as a standby

Staged Pit Dewatering Strategy and Design: Phased plan for pump locations, sump locations and pipelines

Year 1

Year 2

Year 3

Year 4

Year 6

Year 8

Groundwater Modelling Drawdown and Inflows

• 3D numerical groundwater flow modelling completed • Modelling estimates groundwater pit inflows and regional groundwater

level drawdown • Groundwater pumping will generally range between 15 to 40L/s; less

than 10% of the 210-240L/s capacity of the sump pumps which are required to deal with storm run-off

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GW Model Final Pit Drawdown GW Model Pit Inflows

Conclusions

• Mining to be advanced in dry season, creating more flexibility in wet season

• Mining rates and pit design optimised to minimise costs and maximise ore availability

• Good grade control key to maximising recovery from ore

• Increased geotechnical confidence - managing against pit failures

• Surface water flows managed through runoffs and pumping

• Groundwater managed through pumping, drain holes and pit design

• Waste dump design minimises haulage costs, aids safety, water management and restoration potential

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Thank you

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