Aureus Mining New Liberty Project Mining February 2014 Contents - - PowerPoint PPT Presentation

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

0.5 1 1.5 2 2.5 3 3.5 4 4.5 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) - LHS Head 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

Tonnes (Mt)

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
• peration, 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 Mined Ore Grade (Au g/t) Mined Tonnes (Mt)

Mined Ore Tonnes and Grade

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

8

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 Ratio Mined Tonnes (Mt)

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 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 Cumulative Ounces Produced (koz) Ounces Produced (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 Cost per Tonne Mined ($ millions/t) Mining Cost (US$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

14

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)

15

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

16

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

17

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
• n new waste dump and infrastructure
• Storm event pit inflows revised based on

new designs.

18

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

19

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

21

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

22

Thank you

www.aureus-mining.com