Aureus Mining
New Liberty Project
Mining
February 2014
Contents
• Geotechnical
• Pit optimisation
• Pit design
• Mining Contractor
• Groundwater management
• Water management
Geotechnical, Mine design and Water
management support
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
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
140
4.5
4
120
3.5
100
3
80
2.5
60
2
1.5
40
1
20
0
0.5
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
0
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
W
• Total ore mined = 8.5Mt
• Total mined tonnage = 140Mt
E
• Stripping ratio = 15.5:1
• Mining cost $3.06/t mined*
• Gold produced = 859koz
* Includes cost of fleet
5
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, presplit, RC grade control and fixed costs for the life of mine
• New mining fleet agreed
6
Material Movement by Stage
Material Movement by Stage
8.0
Tonnes (Mt)
7.0
6.0
5.0
4.0
3.0
Mining
2.0
1.0
Year 0
Year 1
Year 2
Year 3
Year 4
Year 5
Year 6
Year 7
Year 8
•Staged mining sequence
planned
Stage 1 Stage 2 Stage 3 Stage 4 Stage 5
Larjor
3
Latiff
4
2
Kinjor
1
•2 km long open pit
operation, 220m deep
Marvoe
5
•High grade (3.4g/t) allows
for lower throughput, hence
smaller plant – 1.1Mtpa
7
Ore Production
Mined Ore Tonnes and Grade
0.5
6.0
0.4
5.0
Mined Tonnes (Mt)
0.3
4.0
0.3
3.0
0.2
0.2
2.0
Mined Ore Grade (Au g/t)
0.4
0.1
1.0
0.1
0.0
Year 0
Year 1
Year 2
Mined Ore Tonnes
Year 3
Year 4
Year 5
Mined Grade (g/t)
Year 6
Year 7
Year 8
-
Mined Grade (g/t) FS
8
Waste mining and strip ratio
Mined Tonnes and Strip Ratio
7.0
60.0
6.0
50.0
5.0
4.0
30.0
3.0
Strip Ratio
Mined Tonnes (Mt)
40.0
20.0
2.0
10.0
1.0
0.0
Year 0
Year 1
Year 2
Year 3
Mined Waste Tonnes
Year 4
Year 5
Mined Ore Tonnes
Year 6
Year 7
Year 8
-
Strip Ratio
9
Ounces Produced
45
1,000
40
900
800
Ounces Produced (koz)
35
700
30
600
25
500
20
400
15
300
10
200
5
0
Year 0
Cumulative Ounces Produced (koz)
Ounces Produced and Cumulative Ounces Produced
100
Year 1
Year 2
Year 3
Year 4
Year 5
Year 6
Year 7
Year 8
Gold Produced (Au oz)
Gold Produced (Au oz) FS
Cumulative Ounces Produced FS
Cumulative Ounces Produced
-
10
Cash flows and revenues
Mining Cost and Cost Per Tonne Mined
18.0
3.5
16.0
14.0
Mining Cost (US$M)
2.5
12.0
10.0
2.0
8.0
1.5
6.0
1.0
4.0
0.5
2.0
0.0
Year 0
Cost per Tonne Mined ($ millions/t)
3.0
Year 1
Year 2
Year 3
Total Mining Cost
Year 4
Year 5
Year 6
Year 7
Year 8
-
Cost Per Tonne Mined
11
Grade Control
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
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
FS Nov 2012
Waste Dump located
to south of Pit
• Drainage on the dumps will be managed
14
End of Pre-strip (Year 0)
Construction of;
culverts and flood-ways,
permeable bund locations.
Construction of;
Larjor drainage channels.
Latkin drainage channel.
Construction of;
haul roads,
perimeter safety bund/road.
ROM Pad built up to crusher level
Skyway built.
15
End of Year 1 Mining
Priority dumping in North and North West
Dump reduce haulage distances.
Waste Dump
abuts dam walls.
North, South East and
East Dump built up to
control surface run-off
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.
16
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
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
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
Staged Pit Dewatering Strategy and Design:
Phased plan for pump locations, sump locations and pipelines
Year 1
Year 6
Year 2
Year 8
Year 3
Final Pit
Year 4
Larjor
Number of Sykes HH220i Pumps
Sump Pumps
Transfer Station Pumps
High Head Pump or inclined dewatering
bore(s) used following backfill of Larjor Pit
Latiff
1
Kinjor
1
Marvoe
1
5
1
NB One extra sump pump will be required as a standby
20
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
GW Model Final Pit Drawdown
GW Model Pit Inflows
21
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