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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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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