1 facing the challenges of new low-grade orebodies with new economic circuit designs malcolm powell...
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Facing the challenges of new low-grade
orebodies with new economic circuit designs
Malcolm PowellJKMRC - Queensland
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Driven by uncertainty & variability
• Modify process to respond to uncertainty (S. Begg)
• Vary processing routes to respond to known variability (Powell)
Embrace uncertainty to develop a new range
of economic/business options
The variability of what comes your way
will drive flexible processing
Flexibility to create value
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DRIVERS
Grade
Energy
Water
Massive low-grade ore bodies
Increasing demand
Gold Copper
price
Comminution 36±10% mining energyBallantyne 2011
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• Considerably more challenging orebodies– rapid expansion by exploiting
previously uneconomic deposits
• Rapidly increasing production costs cannot be sustained by continually increasing commodity prices– illustrated by the recent downturn in the industry
A new mining era – a ‘New mining industry’
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• processing of 50 to 100% more ore
same amount of metal
• + finer grain structure - finer grinding
more challenging recovery
tweaking current technologies and relying on economies of scale will not turn the industry around
Switch to considerably more efficient processing
Reduction in grade
Transform processing
capability
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Throughput
Collapse the rich orebody information to a standard single figure used in machine selection and circuit design
Production prediction linked to conventional circuits
average product size
equipment gigantism
Current approach
Current approach is to extract less metal from more ore
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RISK is underperformance for the new orebodies
Conventional circuits operated at historic inefficiencies
Conventional design - locked in history
RoM
Productcyclone
Ball Mill Pump Sump SAG
Geometallurgical Modelling – at great cost and effort –
No Upside
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The value-add of seeking upside
In variability there is a lot of upside
yet we choose to smooth and ignore
blending and daily operation
Upside
lost opportunity in daily operation
Limit
averageNew average
Process output
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• Grade: 0 - 3
• Competence 0.5 -1• Size (F80) 40 – 130
mm
Product requirement• 40 – 100 µm
Specific energy requirement• 11 – 33 kWh/t
• Process fixed at 20±2 kWh/t !
Feed quality - extremely variable
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15
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1399
900
1399
975
1400
050
1400
125
1400
200
1400
275
1400
350
1400
425
1400
500
1400
575
1400
650
1400
725
1400
800
1400
875
1400
950
1401
025
1401
100
1401
175
1401
250
1401
325
1401
400
1401
475
1401
550
1401
625
1401
700
1401
775
1401
850
1401
925
1402
000
1402
075
1402
150
1402
225
1402
300
1402
375
1402
450
ET
1 row of blocks
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kWh/
t
Time 10 yrs
Conditional simulation
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Utilise the properties of the orebody – variability
revolutionising our processing techniques
Our new mantra:
‘Selective mass mining’ with flexible processing
Future approach - Utilise variability
It is time to extract more metal from less ore
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Circuits designed to respond to variation in:– grade– competence– feed size distribution– liberation size
by processing to varying:– target grind size– recovery options– cut-off grades
Considerable, worthwhile challenge to ensure sustainability of our industry
Future approach
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“FlexiCircuits leverage ore variability to maximise resource utilisation”
Providing a range of alternative processing routes for a rock.
Investigate processing options that provide extra capacity
through sophistication rather than scale
smart ore characterisation
economic modelling
innovative processing plant design
FlexiCircuits
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A choice of processing routes
• respond to a wide variability in ore properties and throughput requirements– Shift workload
• slash processing costs and energy utilisation– Blast control
– Reduced milling requirement
– Progressive upgrade
• while enhancing overall recovery– Higher feed grades to flotation
– Alternative recovery routes
Novel Flexible Circuits
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Novel processing routes
Novel or new application of equipment
Devise and test the potential new processes
Requires
Ability to model equipment and circuit performance with confidence
Enabling Technology
Circuit Simulation
Circuit response
Individual machinery is useless
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Examples applied to novel flexible circuit design
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Uneconomic ore-body to viable
Bulk sorter60mm screen
Gyratory
Tag & load
Smart blasting
Flotation
Ball mill
Pebble
crushercyclone
splitterWaste stockpile
screen
Low-grade SP
Ore body knowledge
Ore body knowledge
Bulk grade detector
Split stockpile
Waste rejection
Delayed processing
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full upgrade % of full
tph 10000 6756 68
recov, % 80 82 103
Cu, tpd 960 952 99
Power, MW 113 72 64
specific power, kWh/t 11.3 10.7 95
From uneconomic to viable
2 to 1 processing reduction2x40 ft SAG, 2x26ft ball mill 1x42ft SAG 1x28ft ball mill
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Courtesy CSIRO
Ore body knowledgeKnow what is coming your way & plan when
Model Cells Contain processing parameters
Courtesy CRC Ore
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Coarse Low Grade
Coarse WasteFine High Grade
Ore
Utilise variability – e.g. Blast Engineering by Grade
Coarse low grade
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0
0.05
0.1
0.15
0.2
0.25
0 5 10 15 20 25 30
Fre
qu
en
cy
Fragmentation Size (mm)30025020015010050
1.0
0.8
0.6
0.4
0.2
00
Finely Concentrated Ore
Conventional Blast
Coarse Waste
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Ore body knowledge + flexible flowsheets
Fine waste rejection
Smart tagProcess route Deferred stockpile
Grade detector
Grade detector
Know what is coming your way
Making an orebody viable
No grinding media60% total energy
Stable product+ 3% recovery+25% metal productionUpside40% capacity AG→SAGReduced RISK
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Hybrid Circuit - HPGR - AG
ball Mill Pump Sump SAG
5mm
Coarse flotation
Tailingsconcentrate
600 tphMiddlings
3-product cyclone
RoM 2000tph
LG circuit / heap leach / waste
Dry Clay clumps
• 70% energy• Stable product• Higher recovery• Reduced RISK
50mm
20mm
HPGR
HPGR Feed 2200tph
Wet Screen
-1mm
> water recovery< viscosity issues
RoM 5000tph Dry fluidised bed separator
RejectsWaste sorting
Cone crush
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• Model feed as average– little advantage in complex circuit
• Model variability of feed– advantages of hybrid flexible circuit over SABC circuit– response to ore variability– Multi-component simulation with advanced models
Tuning variable processing to the variable processing regimes
critical to advanced circuit development
High quality ore body knowledge
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Hybrid + Stirred Mill
=
SecondaryCrusher
SAGMill
BallMill
PrimaryCyclones
CCC CC C
2mm
ROM
Smart Blast Design
80mm20mm
10mm
HPGR
PrimaryGyratory Crusher
PebbleRejection
Coarse Waste
Sorting
P/W P/W
SortingRejects
CoarseGangue To Flotation
StirredMill
Tert Grind
Cyclones
Coarse flotation
MiddlingsGrade-by-
size
sorter
Grade splitter
Multi-comp HPGR
Multi-comp crusher
Bimodal feed, multi-component
SAG
3-prod cyclone,
multi-comp
Fine grinding
Coarse recovery
P80?
P80?
P80?
P80?
P80?P80?
P80?
P80?
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• Characterise ore– Base properties– Apply to variable circuits
• Model & Simulate– Multi-component– dynamic
• Pilot– larger capacity– process options
• Control – Dynamic simulation – test on large pilot plant (10 tph)
• Engineer – Physical layout– Turning concepts into reality
Uptake
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Equipment suppliers & Engineering companies
Transform complexity into elegance
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Exploiting lower grade and less favourable ore bodies
→ Doubling comminution energy and processing equipment
→ Unviable
Geomet• higher resolution of ore body knowledge• tracks ore variability• linked to flexible processing incorporating ore upgrade options
Transform currently uneconomic resources into viable and reliable reserves
New Mining Industry
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Design & build with today’s technology,
while allowing the uptake of tomorrow’s technology
for tomorrow’s challenges.
Ensure:
Continued licence to operate
Sustained profitability in the long-term
Flexible circuits – Go Hybrid
P.S.Invest in research,
not mills
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Considerable team effort
CMRCape Town
Rio de JaneiroTU Braunschweig
HacettepeChalmers
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Resource definition (Geomet)
Feeding into
Flexible processing options
Providing
Increased recovery
Greater resource value
Future value
Fresh & feasible
Transform processingConditional simulationUtilising Variability
Process Drivers
Geological model
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