STIRRED MILLING TECHNOLOGY - XPS | Expert Process …IsaMill).pdf · STIRRED MILLING TECHNOLOGY....

STIRRED MILLING TECHNOLOGY

Xstrata Technology – Important expertise in Grinding, Flotation, Smelting, Leaching & Refining

Xstrata Technology Xstrata Process Support

South AmericaSantiago

North AmericaVancouver

Australasia & EuropeBrisbane

Technology CentreSudbury

AfricaJohannesburg

Tankhouse TechnologiesTownsville

Xstrata Technology Xstrata Process Support

South AmericaSantiago

North AmericaVancouver

Australasia & EuropeBrisbane

Technology CentreSudbury

AfricaJohannesburg

Tankhouse TechnologiesTownsville

Presentation Outline

• Technology Development

• Operating Principle

• Key Advantages

• Maintenance Aspects

• Case Studies

Technology Development

• Development driven by inability to efficiently treat fine grained minerals

• Late 1980s, Xstrata required 7 µm grind of Pb/Zn ore for new projects

• Conventional technologies previously tested, 1975-1990

– Too high power consumption to achieve target size

– Ball/tower mills ineffective below 20 to 30 µm

– Negative influence of steel grinding on fines flotation

Broken Hill

0 40 micron

Broken Hill

0 40 micron

McArthur River

0 40 micron

McArthur River

0 40 micron


• Horizontal Bead Mills

– Technology existed in manufacturing (Netzsch)

– Small scale

– Batch operation

– Very expensive exotic media types

• Cross-over from manufacturing into minerals required:

– Much larger scale

– Continuous operation

– Ability to use cheap local media

– Design for easy maintenanceFrom AMIRA P336

Horizontal Bead Mill Technology

Tower Mill Technology


• 1.1 MW IsaMill developed in partnership with Netzsch

– Horizontal, high intensity stirred mill -> high energy efficiency

– Inert grinding environment -> selective flotation, high recovery

– First full-scale IsaMill installed Pb/Zn circuit Mount Isa, 1994

– Enabling technology for McArthur River, 1995


• Technology further developed for coarse grinding. Transfer of IsaMill benefits to coarser grained particles

– Improved energy efficiency– Process benefits from inert media

• Coarse grinding required large mill with suitable media

• Large mill capacity– 3000 litre mill scaled up to 10,000 litres– Motor size from 1.1 MW to 3.0 MW – M10,000 developed jointly with Anglo

Platinum, 2003– Allows significantly higher throughputs – more

suitable for coarser grind applications, better economy of scale

• Suitable media– Coarse inert ceramic media developed by

Magotteaux– High SG (3.7) and coarse size (to 5 mm)– Allows high breakage rates for coarse grinding

Operation – Layout

Motor

Gearbox

ShaftBearings

Rotor

FEED SLURRYWITH MEDIA

GrindingDiscs

SHELL SLIDES AWAY FORMAINTENANCE

Motor

Gearbox

ShaftBearings

Rotor


GrindingDiscs


Motor

Gearbox

ShaftBearings

Rotor


GrindingDiscs


Motor Motor Motor

DISCHARGEDISCHARGEDISCHARGE

Gearbox

ShaftBearings

Product Separator


Shell

DISCHARGE

Typical Configurations:

• M10000 - 2.6-3.0 MW motor• M3000 - 1.1-1.5 MW motor• M1000 – 355-500 kW motor

Inside shell are rotating grinding discs mounted on shaft which is coupled to motor and gearbox.

Operating Principle

Recirculating grinding patterns of media occur between disks due to variation in velocity profile across disks

Media centrifuged to outside of grinding chamber by high centrifugal force generated inside mill

Impeller pumps liquid back into chamber to retain media

Rotor

Shaft rotating at high speeds generating disc tip

speeds ~ 20 m/s

Displacement Body

Multiple stages of grinding

Product exit

Grinding Chamber

Grinding Disks

Shaft

GRINDING MECHANISM & MEDIA RETENTION

PATENTED PRODUCT

SEPARATOR

CLASSIFICATION ZONE

Recirculating grinding patterns of media occur between disks due to variation in velocity profile across disks

Media centrifuged to outside of grinding chamber by high centrifugal force generated inside mill

Impeller pumps liquid back into chamber to retain media

Rotor

Shaft rotating at high speeds generating disc tip

speeds ~ 20 m/s

Displacement Body

Multiple stages of grinding

Product exit

Grinding Chamber

Grinding Disks

Shaft

GRINDING MECHANISM & MEDIA RETENTION

PATENTED PRODUCT

SEPARATOR

CLASSIFICATION ZONE

IsaMill in Action

Media Retention

• Patented PRODUCT SEPARATOR

– Generates G-Force of 60x

– Tip speed ~ 20 m/s

Glass Bead Media

Last Grinding Disc RotorRotor Fingers

(Blurred)

Displacement Body

Glass Bead Media

Last Grinding Disc RotorRotor Fingers

(Blurred)

Displacement Body

Sharp size distribution

Media Addition – Power Draw Control

Feed Slurry

Motor Power Draw Setpoint

Feeder Speed

Controller

Feed Tank

Media Hopper

Feed Pump with VSD

Product

Motor

ISAMILL

Screw Feeder with VSD

New Media

Feed

Feed Slurry

Motor Power Draw Setpoint

Feeder Speed

Controller

Feed Tank

Media Hopper

Feed Pump with VSD

Product

Motor

ISAMILL

Screw Feeder with VSD

New Media

Feed

A Step Change in Technology

KEY ADVANTAGES

• Open Circuit– no closed circuit cyclones, sharp

particle size distribution

• High Intensity– Step change in size, small footprint

• Direct Scale-Up

• Energy Efficiency– Use of fine media

• Inert Media– Downstream process chemistry

benefits

• Horizontal Layout– Simple maintenance– Starts under full load

Open Circuit - IsaMill Internals

• 8 grinding chambers in series – no short circuiting

• Product separator retains media without fine screens

PRODUCT SEPARATORGRINDING DISCS

Open Circuit - Media Load

• High media filling in disc grinding zone ~ 80% - no short circuiting

Sharp Product Size Distribution

KOC RoC Regrind Test - MT1 Media - Open Circuit

0

20

40

60

80

100

0.1 1 10 100 1000Size (um)

Cum

ulat

ive

% P

assi

ng

Feed

20 kWh/t

36.7 kWh/t

57.4 kWh/t

79.1 kWh/t

Narrowing Size Distribution with increased IsaMilling

Minimal over-grinding

Cosmos Nickel Mine

Cosmos Isamill Feed and Product21-03-2009

0

10

20

30

40

50

60

70

80

90

100

1 10 100 1000

Size (microns)

% P

assi

ng

Product Feed

Recently Installed M500 regrinding Rougher Conc


KEY ADVANTAGES




• Direct Scale-Up



benefits


High Intensity - Step Change in Size

• Tower Mill – Max 1.1 MW after 50 years– 40 kW/m3

– Closed circuit with cyclones– Media handling

• IsaMill– Model M10,000 with 3.0 MW motor– 300 kW/m3

– Open circuit with no cyclones– Media system under mill platform

High Intensity – Small Footprint

6.5 MW primary mill &3.25 MW secondary mill

BALL MILLISAMILL

436236Mill Area (m2)

100IncludedMedia Handling (m2)

536236TOTAL AREA (m2)

100%48%RELATIVE FOOTPRINT (%)

613Power per Unit Area (kW/m2)

32503000Installed Power (kW)

Media handling system under IsaMill

3.0 MW M10,000 IsaMill


KEY ADVANTAGES




• Direct Scale-Up



benefits


Direct Scale-Up

• Laboratory/Pilot results scaled directly to commercial size

• Uniform, homogeneous grinding mechanism

• High media load and 8 grinding chambers in series – no bypass

M4 Laboratory Mill M20 Pilot Rig

Direct Scale-Up

• Laboratory/Pilot results scaled directly to commercial size– Uniform, homogeneous grinding mechanism.

1

10

100

1000

1 10 100

P80 (micron)

Spec

ific

Ener

gy (

kWh /

t)

Zinc Ore Grinding Testwork Comparison

Test on M4 Lab Rig

Full Scale - M3000 MillLine of Fit


KEY ADVANTAGES




• Direct Scale-Up



benefits


Energy Efficiency

TYPICAL MILL CONDITIONS

ISAMILLBALL MILL

< 3.5 mm> 20 mm (media too big for efficient grinding)

Media Size

> 230 rpm20 rpm (slow mill)Mill Speed

80%< 45% (half empty mill)Media Charge

TYPICAL MILL CONDITIONS

ISAMILLBALL MILL

< 3.5 mm> 20 mm (media too big for efficient grinding)

Media Size

> 230 rpm20 rpm (slow mill)Mill Speed

80%< 45% (half empty mill)Media Charge

Energy Efficiency

• Fine media, high mill filling & high grinding disc tip speeds key to energy efficiency – better transfer of energy to slurry

• Results in lower kWh/t

2,220176,500,0002IsaMill

370818,00012Tower Mill

222177,00020Ball Mill

Surface Area (m2/m3)

No. Balls / m3 Media Size (mm)

SGvdE .. 23∝

STRESS INTENSITY

•d = media diameter

•v = media velocity

•SG = media density

Energy Efficiency - kWh/t

• What determines Energy Efficiency?

• Energy Efficiency is determined by ore characteristics, media size/type and classification efficiency, when energy input and other operating parameters (density, etc) are held constant

• Decreased media size improves energy efficiency (many studies-200+, eg: McIvor, 1997, Weller,1999, Jankovic, 2002, Nesset, 2006) and type/quality (Kwade, 1996, Curry, Clermont, 2005, Yang, 2006)

• Improved classification efficiency (sharper cut) improves energy efficiency (many studies, eg: McIvor, 1988, Morrell,2008)

• Power measurement and sample segregation in lab mills need to be carefully measured and/or controlled, or lab results will be misleading compared to full scale operation


• Isamill Maxmises Energy Efficiency by– Finer Media Sizing– Energy efficient media types– Improved classification, sharper product size distribution,

due to plug flow through 8 chambers and patented product separator

Weller, Gao - 1999

Media Size Tests


• Isamill Maxmises Energy Efficiency by– Finer Media Sizing– Energy efficient media types– Improved classification, sharper product size distribution,

due to plug flow through 8 chambers and patented product separator

KOC RoC Regrind Test - MT1 Media - Open Circuit

0

20

40

60

80

100

0.1 1 10 100 1000Size (um)

Cum

ulat

ive

% P

assi

ng

Feed

20 kWh/t

36.7 kWh/t

57.4 kWh/t

79.1 kWh/t

Narrowing Size Distribution with increased IsaMilling

Minimal over-grinding

SharpClassification

Reduce Top Size,With Minimal

Fines Production

Batch vs Continuous Laboratory Testing

BATCH TESTING

• A lot of grinding testwork is done in pure batch mode

• Issues with pure batch mode:

– Since no new feed is added, effectively there is ‘continuously reducing feed size’ inside grinding chamber

– No new or recirculate coarse particles added & so easier to achieve target grind at lower energy

– Not realistic compared to full-scale continuous operating mills

• Sub-sampling from top or part of charge measures finer result than bulk mill load

– Need to empty mill & size complete charge, at each sampling time - often not practical

** CONCLUSION **

- Pure batch testing is not representative of full scale operation

- Great care must be taking when performing & considering results from such work

Batch vs Continuous Laboratory Testing

CONTINUOUS TESTING

• Like Batch testing, sample segregation can still be an issue

– need to ensure no retention of coarse particles in mill

• Recommend passing minimum 3 x volume of solids through mill, compared to net mill volume

– to ensure steady state discharge of feed sample

• IsaMillTM testwork is always continuous with feed pumped through mill & product collected from discharge – same as full-scale mill

• IsaMillTM testwork conducted with ~20 l of slurry or ~ 4-5 l of solids (min) – passed through mill with 1.5 l net volume (2.5 l media + internal components)

– Volume of solids is 3 x net mill volume

• IsaMillTM continuous testing is conducted with all process parameters equal to full scale plant. That is,

– Continuous with same feed density, feed pressure, media type & size, internal mixing pattern, power intensity, residence time => same kWh/t

Tower Mill Testing - Segregation Effects

Effect of the feed slurry volume of the 40-litreTower Mill for grinding #4 SAG01 cyclone overflow

Product P80, microns

100

Net

Ene

rgy

Con

sum

ptio

n, k

Wh/

t

2

3

4

56789

20

1

10

150 litres of feed slurry50 litres of feed slurry

Energy Efficiency – Tower Mill Comparison

Signature Plot - P80: IsaMillTM vs Tower Mill

1.00

10.00

100.00

1.00 10.00 100.00 1000.00

Size (µm)

Spec

ific

En

erg

y (k

Wh

/t)

P80 IsaMill Test 1

P80 IsaMill Test 2

P80 Tower Mill Test 1

P80 Tower Mill Test 2

RESULTS OF TESTWORK ON MAGNETITE

• M4 IsaMill 4 litre mill, operating with 3.5 mm ceramic Keramax MT1 media

• Tower Mill 40 litre capacity operating with 12mm steel media

At P80 of 35 µm:

• Tower Mill = 32 kWh/t

• IsaMill = 18 kWh/t

ISAMILL USES UP TO 45% LESS POWERF80 = 110 µm

Comparing Testwork Results

• When comparing grinding results for scale-up, recommend all testwork be conducted in following manner:

– Continuous

– 3 x volume of solids through mill, compared to net mill volume

– Use same media size & type as will be used in full-scale (ie. not smaller media)

– Maintain consistency when measuring particle sizes (ie. screen vs laser sizing)

– Maintain consistency in power draw measurement –recommend electronic kWh meters measuring direct mains power supply

– MIMIC CONDITIONS OF FULL-SCALE MILL


KEY ADVANTAGES




• Direct Scale-Up



benefits


Recent Developments in Grinding Media

Inert Ceramic Media

• Smaller than Steel Media which increases power efficiency

• Smooth, ‘pearl like’, low friction losses and low kinetic energy losses - increases power efficiency

• Excellent wear characteristics – very hard, excellent mechanical integrity

• Lower wear rates than steel media (5-15 g/kwh for Ceramic compared to 40-50g/kwh for Steel)

• High density –> high power draw compared to sand media

• Coarser available ceramic media allows higher breakage rates of coarse particles

• More & more quality ceramic suppliers entering market which is bringing price further down -> positive for IsaMillTM user

Inert Media – Media Types & Effect

Inert Media Benefits compared to Steel:

• Fe forms complex with cyanide – increased cyanide consumption

Negative impactflotation/leach kinetics

Steel media Fe hydroxides

Precipitate/coatparticle surface

MEDIA TYPES

• Ceramics

• Silica sand

• Autogenous (the ore itself)

• Smelter slag

Slag RiverSand

OreSlag RiverSand

Ore

Profound Impact of Inert Grinding

Cullinan,University of Sth Aust, 1999, tests on Rapid Bay Galena

Sample ground to P80=15 microns to enhance media effects

Inert Media vs Steel Media

• AMIRA P260

Effects of grinding medium and gas purging on arsenopyrite (FeAsS) flotation (Huang et al., 2006)

Improved recovery of fines – steel media has significant negative

effect on large surface areaImproved recovery with

inert ceramic media

Impact of Inert Grinding - Chalcopyrite

Fines Flotation at Mount Isa Pb-Zn

Recovery by size in the Zinc Retreat CircuitAfter Isamill Inert Regrinding to P80 = 7 microns

0.0%

10.0%

20.0%

30.0%

40.0%

50.0%

60.0%

70.0%

80.0%

90.0%

100.0%

C7 C6 C5/C4 C3-C1 38/53 75

Size fraction

Zinc

Rec

over

y in

siz

e fr

actio

n %

0.0%

5.0%

10.0%

15.0%

20.0%

25.0%

30.0%

35.0%

40.0%

45.0%

50.0%

Zinc

Dis

trib

utio

n in

Fee

d %

Zinc Distribution in Feed Zn Recovery by Size


KEY ADVANTAGES




• Direct Scale-Up



benefits


Horizontal Layout - Benefits

• Wide operating range. Continuous turn-down

• Horizontal configuration enables large scale designs – up to 3.0 MW

• Shell on wheels. Easy maintenance. Single component lifts

• Low breakaway torque

• Restart after crash stop is no problem

3 models available to accommodate different capacities• M10,000 - 2.6 to 3.0 MW motor• M3000 - 1.1 to 1.5 MW motor• M1000 - 355 to 500 kW motor

M10,000 M3000 M1000

Isamill Layout

Maintenance Aspects

• Developmental focus of IsaMill - minimum operating costs and maximum availability

• Equipment designed for fast and straight-forward maintenance

• All major components at one level with shell components on rails - very easy access to wear items

• IsaMill maintenance completed during routine plant shutdowns

• Every 4 to 8 weeks, for 2 to 8 hours. Availability 97+%

Maintenance Aspects

Shell slides along hydraulically operated rails for maintenance access

Maintenance Aspects

Discs removed from shaft using overhead crane

Typical Wear Component Life:

• Set of Disposable Grinding Discs ~ 6 months

• Disposable Shell Liner ~ 12 months

Fabrication

• All mills trial assembled in Germany


KEY ADVANTAGES




• Direct Scale-Up



benefits


IsaMill Technology can change the way plants are designed:

• Replace tower or ball mills

• Simplify flotation circuits

• Produce higher grades to smelters

Case Studies

• Fine Grained ores for flotation : – McArthur River – George Fisher– Mt Isa Open Cut

• Standard Regrinding Duties

• Coarse Main Stream Grinding

Myths about Fines flotation

• Fines don’t float

• Fines need more reagent

• Fines need special flotation cells

• Fines need more flotation cells

How the Fines Myth Started ...

Size (microns)

Recovery

5 10 30 50 20080 100 150

Liberated Fines :

High surface area

Need high collector

and low depressant

Intermediate : fast floating

lower collector need,

composites need depressantCoarse Particles

Low liberation

The Problem with fines ….

• … is actually a problem of mixing fines with coarse composites

• … and with steel media

Easily solved with inert media, good classification

and simple circuit design

Zinc Concentrate +C3 Size Fraction

+16um

Fines flotation - a different perspective

• 96% of recovered particles are less than 2.5 microns

• P50 is 2.5 microns

• MRM grinds to P80 of 7 microns

• ….. Fines do float !

• 85% recovery into high grade concentrate

McArthur River

• Lead/Zinc Bulk Con - P80 7 micron, 5 x M3000 (1.1 MW)

The Problem with composites ….

• A fine liberated particle has a similar flotation rate to a coarse composite

• The conditions to depress the composite also depress the fines

• Recirculating the depressed fines compounds the problem

Circuit design for Fines Recovery

• Only grind what you really have to

• Use grinding to improve surfaces, not harm them

• Efficient grinding with sharp classification

• Float as soon as possible after grinding

• Float in narrow size distributions

• Do not recirculate cleaner tails

Size (microns)

Recovery

5 10 30 50 20080 100 150

Intermediate and coarse behaviourFines performance when

treated by themselves

Fines peformance when

treated with coarse particles

Applying Fine Flotation Principals : Conceptual Stage Grind Circuit

View of IsaMill Regrinding Section

7um Regrind / Float

Mt Isa Pb / Zn Concentrator Flow Sheet

70um Primary Grind/Float 37um Secondary Grind / Float

12um Regrind / Float


Rod & Ball Milling

Tailings

Prefloat Pb Ro

Ball Milling

Pb Ro / Scav Zn Ro Zn Ro / Scav

Tailings

Zn Conc

Zn Columns

3 x 1.1MWIsaMills

Pb Conc

Jameson Cell

Pb Cleaners

1 x 0.52MW Tower Mill

2 x 1.1MWIsaMills

Zn Cleaners

3 x1.1MWIsaMills

Zn Retreatment Cl

Zn Retreatment Ro

Zn Conc

Zn Conc

Tailings

Pb Conc

33% Pb Rec

46% Pb Rec

37% Zn Rec

39% Zn Rec

6% Zn Rec

Zinc Recovery Performance of the Concentrator

62.50

65.00

67.50

70.00

72.50

75.00

77.50

80.00

82.50

Apr May1999

Jun Jul Aug Sep Oct Nov1999

Dec Jan Feb2000

Mar Apr May Jun Jul Aug Sep Oct2000

Nov

Month

IsaMills commissioned

October 1999

Baseline

First Wave+5% Zinc Recovery

Reduced grinding/flotation capacity,due to equipment relocation during construction.

Plant Stabilisation &Plant Optimisation

Second Wave+5% Zinc Recovery

IsaMills made more fines and increased fines recovery Zn Recovery vs Size - before and after IsaMilling

0

20

40

60

80

100

1 10 100

SIZE (microns)

Apr-99

Oct-00

Whole circuit recovery, roughing and cleaning, including losses to lead concentrate

Moved particles from low recovery and low grade fraction

to higher recovery and higher grade fines fraction

Increased recovery in fine sizes

Net result - 10% recovery increase and 2% concentrate grade increase

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

C7 C6 C5/C4 C3/C2 C1/38 53 75

Size fraction

0.0%

5.0%

10.0%

15.0%

20.0%

25.0%

30.0%

35.0%

40.0%

45.0%

50.0%

0-4um 4-8um 8-16um 16-30um 30-53um

Recovery

Size Distribution

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

C7 C6 C5/C4 C3/C2 C1/38 53 75Size fraction

Zinc

Rec

over

y in

siz

e fr

actio

n %

0.0%

5.0%

10.0%

15.0%

20.0%

25.0%

30.0%

35.0%

40.0%

45.0%

50.0%

0-4um 4-8um 8-16um 16-30um 30-53um

Recovery

Size Distribution

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

C7 C6 C5/C4 C3-C1 38/53 75

Size fraction

Zinc

Rec

over

y in

siz

e fr

actio

n %

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

0-4um 4-8um 8-16um 16-38um 38-75um

7um Regrind / Float

70um Primary Grind/Float 37um Secondary Grind / Float



Rod & Ball Milling

Tailings

Prefloat Pb Ro

Ball Milling

Pb Ro / Scav Zn Ro Zn Ro / Scav

Tailings

Zn Conc

Zn Columns

3 x 1.1MWIsaMills

Pb ConcJameson Cell

Pb Cleaners

1 x 0.52MW Tower Mill

2 x 1.1MWIsaMills

Zn Cleaners

3 x1.1MWIsaMills

Zn Retreatment Cl

Zn Retreatment Ro

Zn Conc

Zn Conc

Tailings

Pb Conc

33% Pb Rec

46% Pb Rec

37% Zn Rec

39% Zn Rec

6% Zn Rec

Combine for Overall Circuit Recovery …

37 micron circuit 12 micron circuit

7 micron circuit

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

C7 C6 C5/C4 C3-C1 38/53 75

Size fraction

Zinc

Rec

over

y in

siz

e fr

actio

n %

0.0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

0-4um 4-8um 8-16um 16-38um 38-75um

Recovery

Size Distribution

Mt Isa Zinc Circuit Recovery by Size

Impact of Fine Grinding for George Fisher Ore

• - same unit cost with 8MW additional grinding power

• - 5% increase in lead recovery

• 8 MW of IsaMills and Stage Grind and Float led to :

• And :

• - 5% increase in lead concentrate grade• - 10% increase in zinc recovery

• - 2 % increase in zinc concentrate grade

• - lower circulating loads

• - less reagents !

• - much simpler ciruit

• - very small increase in flotation capacity

The Scientific Method ….

• Understand impact of

• - size by size

• Describe mineral behaviour ...

• Account for effect of

• - mineral by mineral• - by liberation class

• - bulk properties

• - surface and solution chemistry

• - operating constraints

• - materials handling

Case Study : Mt Isa Blackstar Open Cut Ore

• Fine grained, low grade

• Pyrite and sphalerite activated by leaching– non selective flotation, low con grades

• Conventional technology unable to make smelter quality con at any recovery - 80 years of research

• Enabled by IsaMill flotation circuit– low cost liberation– surface cleaning by attrition– pulp chemistry after inert grinding

Blackstar Ore Mineralogy

Lead Grade Recovery -Conventional vs IsaMills

Pb Grade/Recovery Curve - ISA Lead-Zinc Transition Ore

0

10

20

30

40

50

60

70

80

0 10 20 30 40 50 60 70 80 90 100

Pb Recovery

Pb G

rade

Conventional Circuit with Steel Grinding

Results with IsaMill Inert Grinding

Result : Approval of Open Cut in 2004, treatment commenced Mar 05

Anglo Platinum, South Africa

Anglo Platinum, South Africa

• Mainstream Inert Grinding – F80 120 µm to P80 53 µm grind

• Concentrate Regrinding – shift grade

• Production expansion

• Shift in grade has potential to postpone major smelter expansion

• Fraction of overall energy consumption by grinding compared to smelting

BHPB Leinster, Western Australia

• 3.5 unit increase in Ni grade with IsaMill regrind

• 30% reduction in MgO to concentrate

• Significant implications for smelter performance

Published at Mill Operators Conference 2008

Recent Commissioned Projects– Coarse Regrind Duties

• Phu Kham (Laos, SE Asia)– Copper/Gold

– Rougher Concentrate feed (168 tph)

– F80 = 106 µm, P80 = 38 µm

– 2.6 MW M10,000

– Commissioned early 2008

• Prominent Hill (South Australia)– Copper Gold

– Rougher Concentrate feed (138 tph)

– F80 = 125 µm, P80 = 24 µm

– 3 MW M10,000

– Commissioned early 2009

Case Study – Prominent Hill

IsaMillTM Densifying Cyclones

Jameson Scalper Cell

Roughers

1st Cleaners

2nd Cleaners

3rd Cleaners

Final Concentrate

Final Tails

Float Feed

ISAMILLTM

REGRIND CIRCUIT

Case Study – Prominent Hill

• Jameson Cell in conjunction with IsaMillTM as scalper cleaner directly after regrinding

• Fast flotation device ideal to treat fine, fresh surfaced particles generated in IsaMillTM

• High grade concentrate with below spec fluorine level

• Currently 40 - 50% Cu grade at 60 - 86% recovery with respect to feed in single stage unit

Case Study – Teck Cominco, Red Dog, Alaska

• Purchased 2 x M3000, 1.5 MW IsaMillsTM

• Red Dog has been operating since 1989, & produces over 1.0 Mt/y of zinc concentrate & 0.23 Mt/y lead concentrate

• Currently circuit uses up to 10 vertical tower mills for regrinding intermediate flotation streams

• New IsaMillsTM will allow 7 of existing tower mills to be shutdown, while improving grinding capacity & zinc recovery

• Decision made after extensive on-site comparative testwork by Teck Cominco technical & research teams

• While some flotation benefits expected from inert media, energy efficiency was prime consideration

• Remote Arctic location means all power is diesel generated, & diesel can only be shipped during brief Arctic summer

Upcoming IsaMillTM Commissioning Projects

• Somincor (Portugal)– Cu / Zn

– Rougher concentrate feed (15 t/h)

– F80 = 45 µm, P80 = 8 µm

– 1 x 1.5 MW M3000 IsaMillTM

– To start commissioning May ‘09

• Penasquito (Mexico)– Pb / Zn / Ag / Au

– Pb Rougher concentrate feed (402 t/h)

– F80 = 125 µm, P80 = 30 µm

– 2 x 3 MW M10,000 IsaMillsTM

– Zn Rougher Concentrate feed (268 t/h)

– F80 = 125 µm, P80 = 25 µm

– 2 x 3 MW M10,000 IsaMillsTM

– To start commissioning August ‘09

Primary Grinding Circuit IsaMillTM

– McArthur River Project

• Originally designed for fine grinding

– Mount Isa, McArthur River

• IsaMillTM applications are changing

– Coarser regrinding duties

– F80 > 250 µm

• McArthur River Primary Grind Project

– Increased plant tonnage from 250 t/h to 350 t/h with closing of underground mine & opening of open-cut mine

– More primary grinding capacity required

– Rather than increase SAG mill capacity, evaluation showed more efficient alternative to use IsaMillsTM

– With higher tonnage, coarser SAG mill product would be generated & treated directly in large 3 MW IsaMillsTM

George Fisher, Mt Isa, Australia



• Initial M20 trials results obtained in 2006

– Results confirmed that grinding feed up to F80 of 300 µm was possible

• Extensive full scale on-site plant work conducted in 2007 in existing M3000 IsaMills confirming results

• Objective - determine conditions needed for coarse grinding duty:

– Selecting appropriate media size

– Studying effect of operating density

– Evaluating effect of feed size

– Evaluating media consumption data

M3000 IsaMillsTM - McArthur River, NT, Australia

Coarse Grinding at MRM

Ore stockpile

Feeder

Screen

Tower Mill 935kW

Primary Cyclones

SAG Mill 6.1mx7.32m EGL Allis 4MW

Flotation Feed

IsaMill

M3000 Isamill treating a blend of Cyclone Underflow and some Cyclone Overflow


1

10

100

10 100 1000

P80 Size (m icrons)

Net

Ener

gy

(kW

hr/

t)

Tower Mill Operating Point

55-60

IsaMill operating point at equivalent energy input to Tow er Mill

IsaMill Testw ork


150-200 micron feed

Size Vs Ener gy f or F eed of 1 50-200 m ic rons

y = 12 4 1 .6 x -1 .2 9 2 4

R 2 = 0.9 3 95

1

1 0

1 0 0

1 0 1 0 0P8 0 S ize [m icro n s]

Ne

t E

ne

rgy

[k

Wh

9

45µm



200-250 micron feed

11

45µm

Size Vs Energy for Feed of 200-250 microns

y = 137.96x-0 .6855

R2 = 0 .8774

1.0

10.0

100.0

10 100P80 Size [microns]

Net

En

erg

y [

kWh

r/t]




• 2 x M10,000 (3 MW) Primary Grinding IsaMillsTM

- commissioned late 2008

Installation & Commissioning, NT, Australia

IsaMillTM Technology Growth

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

1992 1994 1996 1998 2000 2002 2004 2006 2008 2010

Cu

mu

lati

ve In

stal

led

Po

wer

(M

W)

Mt Isa Pb Circuit

McArthur RiverGeorge Fisher

McArthur River Expansion KCGM GidgiKCGM Fimiston

Lonmin EP-C

Anglo Platinum WLTRP

Centerra Gold KumtorPhelps Dodge Morenci

Anglo Platinum PPL-C

Anglo Platinum PPL-A/BAnglo Platinum Waterval UG2

IsaMillTM

CommercialisationM10,000

Development

Oceana

Phu Kham

Prominent Hill

McArthur RiverAnglo Platinum Amandebult UG2 #2

Anglo Platinum Amandebult UG2 #2

Anglo Platinum Amandelbult Merensky Plant Anglo Platinum Amandelbult UG2 #1

Anglo Platinum Waterval Retrofit

Anglo Platinum Waterval Retrofit UFG

Anglo Platinum PPRust North

Anglo Platinum PPRust North UFGAnglo Platinum BRPM

Caribou

Penasquito I (Goldcorp)

Leinster Nickel (BHPBilliton)

Penasquito II (Goldcorp)Dominicana Gold

Boynton

ClimaxRed Dog

Somincor

Cosmos Nickel

Korea Zinc

Year

GREEN - M1000

BLUE - M3000

RED - M10,000

ORANGE – M500

ISAMILLGRINDING TECHNOLOGY

Thankyou. Questions ?www.isamill.com / www.xstratatech.com

STIRRED MILLING TECHNOLOGY - XPS | Expert Process …IsaMill).pdf · STIRRED MILLING TECHNOLOGY....

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