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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
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
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
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 on 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
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