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MMMA President’s Seminar Stilfontein, May 20th 2011

“Fine grinding – UG2 processing”Chris Rule

Head of Concentrator TechnologyAnglo American Platinum

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Agenda

Background

UG2 ore’s growing importance – challenges!

Stirred milling in AAP

Stirred Milling in the mining industry SA/worldwide

Latest trends

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AAP Concentrators

Varied reef types have driven circuit design Mineralogy is key to identifying opportunity! AAP has driven large investment in Anglo Research’s capability for

operational routine samples and technology/project input

Complex circuits with multi stage grinding and flotation MF1 with crushing/screening evolving to MF2 and MF3 over time

Due to the value of the PGM basket; metals recovery is/has been and will be the primary objective for Concentrator operations,

AAP’s scale of mining operation in the range 120 000 to 1 million tpm – multi plant platform, most often the Concentrator is not the constraint

Modernization and rationalization of Concentrator plants largely completed in last decade

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Macro factors

• Energy costs are increasing; power availability, carbon footprint/tax?

• PGM basket price increasing steadily due to supply demand

• Mining is becoming deeper and more expensive

• PGM market is growing steadily driving expansion of supply

• Head grade dropping with time, ores more difficult metallurgically, especially UG2

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9

MIG stirred Mill

Primary Rougher

Ball mill

-8mm

SecondaryRougher Final tails

Regrind Ball mill

MF2 circuit

Stage milling and flotation

• Stage grinding introduced in late 80s-early 90s to improve liberation and recovery

• At Waterval - 1987 first two regrind mills; second two in 1990

• Merensky only processed in this period

40.0

45.0

50.0

55.0

60.0

65.0

70.0

J M M J A O D F A J A O D F A J A O D F A J A O D F A J A O D F A J A O D

Fin

al G

rind

(%-7

5um

)

1986 1987 1988 1989 1990 1991

80.0

81.0

82.0

83.0

84.0

85.0

86.0

87.0

88.0

89.0

90.0

J M M J A O D F A J A O D F A J A O D F A J A O D F A J A O D F A J A O D

Rec

over

y (%

)

1986 1987 1988 1989 1990 1991

• MF2 circuits critical for UG2 and Platreef due to liberation size now much finer

• Waterval first site, quickly followed group wide and at all new flow sheets employed from 1990s

• UG2 from late 1980s and Platreef exploited from 1993

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Multi plant platform• Rustenburg - Waterval (620 ktpm)

• Rustenburg - Waterval UG2 (450 ktpm)

• Rustenburg – WLTR (450 ktpm)

• Amandelbult – Merensky (320 ktpm)

• Amandelbult - UG2#1 (220 ktpm)

• Amandelbult - UG2 #2 (210 ktpm)

• Union - Mortimer UG2 (240 ktpm)

• Union - Mortimer Merensky/UG2 (110ktpm)

• Union - Mortimer Slag/UG2 (65 ktpm)

• Union – Ivan (110 ktpm)

• Mogalakwena – MSC (385 ktpm)

• Mogalakwena – MNC (600 ktpm)

• Mototolo UG2 – (220 ktpm)

• Unki MSZ – (120 ktpm)

Managed Operations

14 plants with total monthly nameplate capacity of 3.5 million tonnes ROM per month

In FY 2010 produced 1.74 million ounces Platinum

Further production from JV and shared mining operations, (7 plants).

Kroondal/Marakana – UG2, 3 plants

Bokoni, UG2 and Merensky 2 plants

Modikwa UG2: BRPM Merensky/UG2

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UG2 Ore characteristics

• Since late 90’s switch from Merensky to UG2 and Platreef, and now MSZ

• UG2 is the major ore source for AAP and the industry in South Africa

• UG2 and Platreef - complex mineralogy and increasingly more difficult to attain good extractions

• Average PGM minerals grain size finer; < 10 micron in UG2 and greater dissociation from sulphides into gangue

Milling data 1999 to 2009

0

10

20

30

40

50

60

70

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009

% r

eef

typ

e o

f to

tal

mil

led

0.00

1.00

2.00

3.00

4.00

5.00

6.00

gp

t P

GM

4T

UG2 % of total processed

Platreef as % total processed

Built-up head grade gpt 4T

1 µm

0%

20%

40%

60%

80%

100%

Feed Concentrate Tailings Tailings-10 Tailing+10 Tailings +53

Are

a %

Liberated Enclosed in BMS Attached to BMS PGM/BMS associated Enclosed in silicate

Attached to silicate Grain Boundary Enclosed in oxide Attached to oxide

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UG2 ore typically contains finer PGM mineralization and often a greater proportion is dissociated from larger grain sulphides

Initial UG2 circuits derived from Merensky practice

Recovery of UG2 typically 75-85% dependant on PGM grain size and degree of sulphide disassociation and alteration effects

The recovery potential at conventional grinds will deteriorate unless circuits change

Ore mineralogy - UG2

5 µm

10 µm

Silicate

BMS

PGM

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Typical UG2 tailings PGM losses

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Summarized AAP UG2 process flow

MIG stirred Mill

Feed

TankFAG/SAG primary mill

Chrome split cyclon

e

Silica ball mill

Primary Rougher

Chrome ball mill

ROM

FF/ ChromeRougher

SecondaryRougher

Final tails

UG2 processing – “MF2” with split regrind and flotation

Majority of ore is now processed through these circuits as UG2 or UG2/Merensky/other mixed feeds – fifteen plants out of twenty one!(Two are Merensky, one MSZ, one tailings retreatment and two Platreef)

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The new stirred milling technology was evaluated from 2000

The potential was demonstrated and the opportunity identified and a strategy put in place

Two applications were targeted

UFG – or ultra fine grinding i.e. conventional concentrate regrind to improve the grade/recovery relationship and potentially reduce the smelting requirement,

80% - 15-20 microns

MIG – mainstream inert grinding; improvement in primary metals recovery by regrinding secondary ball mill products

80% - 50 microns

Stirred Milling – origins in AAP

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2001, The WLTR; Western Limb Tailings Retreatment Project was identified as the low risk “vehicle” to be used to scale up and prove the IsaMill stirred milling technology to unit size that would support the mainstream opportunity:

Stirred Milling – AAP’s timeline

2003, World’s first M10000 IsaMill developed with Xstrata Technology and Netzsch Feinmahltechnik; commissioned on silica sand in UFG duty

2004, A focused on site pilot test work programme was initiated to identify the applications that could be financially motivated

2006, First mainstream or MIG IsaMill application commissioned in 2006 at Mogalakwena South C section - regrinding secondary ball mill product

2006, Establishment of a dedicated ceramic media development programme to ensure the sustainability of stirred milling technology with ceramic medias

2009, 23 MIG and UFG stirred mills in operation; 22 IsaMills and 1 Metso SMD:18 MIG applications and 5 UFG applications, 64.5 MW of capacity

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Feed from the Mine

PrimaryMilling

SecondaryMilling

Sidestream

Mainstream MIG Circuit

Flotation

Flotation

Mainstream Inert Grinding (MIG) is designed to improve recoveries by optimising liberation in an

‘inert’ media environment

UFG Circuit

Ultra-Fine Grinding (UFG) reduces the mass pull through better liberation, surface cleaning and

improving the selectivity between gangue and value minerals

Tailings

TailingsCleaning

Flotation

Flotation

High Grade High/Medium Grade Low GradeBypass

Bypass

Smelters

Stirred Milling MF2 PGM Flow sheet

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Larger scale mills:Mt Isa Mines –Pb/Zn circuits 1995 3000 litres Anglo American Platinum 2003 10 000 litres

Laid the foundation for mainstream application in PGM industry

Stirred Milling – scale up

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Jan-

08

Mar

-08

May

-08

Jul-0

8

Sep-0

8

Nov-0

8

Jan-

09

Mar

-09

May

-09

Jul-0

9

Sep-0

9

Nov-0

9

Jan-

10

Mar

-10

May

-10

Jul-1

0

Sep-1

0

Nov-1

0

Jan-

11

Mar

-11

83

84

85

86

87

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90

91

92

93

Waterval Site Platinum % Recovery

Linear (Waterval Site Platinum % Recovery )

Amandelbult Site Platinum % Recovery

Linear (Amandelbult Site Platinum % Recovery)

• Post commissioning of the MIG IsaMills at Rustenburg and Amandelbult

• Step change in metallurgical performance!

• Platinum recovery improvements– Waterval UG2 > 5%– Amandelbult UG2 ~ 5%

• Site recovery includes tailings scavenging

Site recovery increasing

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Tails values - historical low

• Post commissioning of the MIG IsaMills at Rustenburg and Amandelbult - step change in metallurgical performance

• Lowest tailings values in the history of these operations

• At ~2/3rds UG2 ROM feed and dropping head grades

POST MIG RESULTS

YTD YTD YTD YTD YTD 15 months best 6 months

2005 2006 2007 2008 2009 2010/2011

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

4E tailings values

Waterval 4E tails

Amandelbult 4E tails

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UFG stirred milling

• 4 mills installed and recently commissioned– Amandelbult UG2– Waterval– MNC– Mototolo, (SMD)

• Results promising to date– All testwork AAP has done

shows the grade/recovery shift

• Benefit due to better liberation but also due to intense surface attritioning action in inert grinding environment

Product grade & recovery

shift

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0.0

0.5

1.0

1.5

2.0

2.5

3.0

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

Cr2O

3 in c

once

ntrate

feed

to W

aterva

l Sme

lter (

%)

0

10

20

30

40

50

60

UG2 m

ined o

f total

outpu

t (%)

Cr2O3 UG2 mined of total output 30 per. Mov. Avg. (Cr2O3)

Chromite control – AAP view

4-fold increase in Cr2O3 in furnace feed over past decade!

Not a smelter problem! – must be solved in the Concentrators

New technology is the only solution and is available now

UFG stirred milling

Column flotation technology

Circuit configuration

Blending – Platreef, MSZ and Merensky

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IsaMill installations at Anglo Platinum

Waterval Concentrator MIG & UFG

Amandelbult UG2 #2 Concentrator MIG & UFG

Mogalakwena South Concentrator C section – the first MIGMogalakwena South

Concentrator A & B MIGs

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Stirred milling - worldwide

• Growing acceptance of this technology in the mining industry,

• IsaMillTM Users 2011:– AA Platinum; Xstrata Technology; Netszch; Xstrata Cu/Zn/Ni;

Lonmin; Oz Minerals; Vale; Goldcorp; Teck; Freeport McMoran; Endako;

– Newcrest; Platmin; Centerra; Oceana Gold; Lundin; Kemira; Pan Australian; Blue Note Metals; Cetco; Korean Zinc; BHP; Dominicano Gold; Somincor; Eldorado Gold; Exportadora Aurifera

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Stirred mills in mining

PtMile tails – SMD 355 & Deswik 2000 L 2 setsSylvania – SMD 185 & SMD 18.5 – 8 setsImpala – SMD 355 2 sets tails scavenging

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PGM industry & stirred milling

Operator Operationnumber of stirred

mills typeinstalled power

kW application

Anglo Platinum/JVs WLTR 1 IsaMillTM M10000 2600 UFG/MIG

Waterval UG2 2 IsaMillTM M10000 6000 MIG

Mogalakwena South 3 IsaMillTM M10000 9000 MIG

Mogalakwena North 4 IsaMillTM M10000 12000 MIG

Waterval 4 IsaMillTM M10000 12000 MIG

Amandelbult 4 IsaMillTM M10000 12000 MIG

Amandelbult 1 IsaMillTM M3000 1500 UFG

Mogalkwena North 1 IsaMillTM M10000 3000 UFG

Waterval 1 IsaMillTM M10000 3000 UFG

Mototolo 1 Metso SMDTM 355 355 UFG

RBR BRPM 1 IsaMillTM M10000 3000 MIG

Lonmin Eastern Platinum C 1 IsaMillTM M3000 1000 UFG

Eastern Platinum A/B 1 Metso SMDTM 355 355 UFG

Platmin Boynton 1 IsaMillTM M3000 1500 MIG

Impala Rustenburg TRP 2 Metso SMDTM 355 710 UFG

Platinum Mile Paardekraal TRP 2 Metso SMDTM 355 710 UFG

Paardekraal TRP 2 Deswik-2000 litre 1065 UFG/MIG

Aquarius/JV RK1 chromite tails 1 Deswik-1000 litre 500 MIG

Sylvania Steelpoort 2 Metso SMDTM 185/18.5 203.5 UFG/MIG

Lannex 1 Metso SMDTM 185/18.5 185 UFG/MIG

Lannex 1 Kings 75 MIG

Millsell 2 Metso SMDTM 185/18.5 203.5 UFG/MIG

Tharisa Brits chrome TRP 1 Deswik-500 litre 220 MIG

PGM Concentrators

PGM Tailings retreatment

Chromite tailings retreatment

From 2002 until 2010; 39 milling units and ~ 71 MW installed; mainly in PGM Concentrators, but also in tailings scavenging for PGMs from primary and secondary sources – PGM and chromite industry

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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

Cum

ulat

ive

Inst

alle

d Po

wer

(MW

)

Mt Isa Pb CircuitMcArthur River

George FisherMcArthur River Expansion KCGM Gidgi

KCGM Fimiston

Lonmin EP-C

Anglo Platinum WLTRPCenterra Gold Kumtor

Phelps Dodge Morenci

Anglo Platinum PPL-C

Anglo Platinum PPL-A/B

Anglo Platinum Waterval UG2

IsaMillTM CommercialisationM10,000

Development

Oceana

Phu Kham

Prominent Hill

McArthur River

Anglo 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

GREEN - M1000BLUE - M 3000RED - M 10,000

Caribou

Penasquito I (Goldcorp)

Leinster Nickel (BHPBilliton)

Penasquito II (Goldcorp)Dominicana Gold

Boynton

ClimaxRed DogSomincor

Rapid growth in IsaMillTM installations

10/22

Pb & Zn industry

Au industryAustralia

Anglo American Platinum

Anglo American Platinum MIG and UFG IsaMill Projects

250 $ million investment

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Current installed/ordered, AAP role

• 86 IsaMills in the mining industry

• AAP has 22 units or roughly ¼ BUT has more than ½ of the installed drive power

• AAP plays a leading user role for the technology

• AAP developed the first 10000 litre mill in 2001/2002 with Xstrata technology and Netzsch • thus allowing future mainstream applications once the

ceramic media was developed for economic operation

• AAP commissioned the first mainstream IsaMillTM application in 2006 at Mogalakwena South Concentrator

• AAP has 22 IsaMills and a further 4 in the project cycle currently

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• 8 grinding chambers in series – no short circuiting; intense milling – disc tip speed ~20m/s

• Product separator retains media without fine screens; components -rubber or polyurethane

PRODUCT SEPARATORGRINDING DISCS

DISCHARGE RING

Note – not a screen. Flow directional device

Large Aperture – 12.5 mm (½ inch)

Mill layout and design

2/22

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Technology optimization

• MIG, UFG and FG classification, duty and feed size

• Equipment Optimisation, • component design for duty, SDD and disc geometry, 7 vs 8 disc,

rotor design, inlet; rotor reversal for maintenance; media recovery and feeding – “jet pump” replacing screw feeder

• materials of construction; alternative supply• evolution of coarse mill design – M5000/(M3000)

• Circuit optimization; • tramp protection; media load positional control; on line temperature

measurement; DEM; acoustic; PET,• reccyle and feed preparation and delivery,• ceramic media development

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Trends observed

• Applications widening:• UFG; UFG and FG• mainstream and concentrates regrind

• Commodities• Pb/Zn – Au – Ag – Cu – Ni – PGMs• Magnetite; Mo;

• Duty• liberation concentrate regrinding; UFG and FG• pre leach grinding; UFG• mainstream liberation regrind; MIG • coarser applications – media size 6 mm; feed size 300 microns

• Recent • copper rougher concentrate regrind – Las Bambas/Antapaccy• comparative energy data being generated vs tower milling/ball

milling

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Operating cost reduction

• Advances in operating control; maintenance practice and competition in ceramic media supply and wear part supply is reducing operating costs,

• Ceramic media consumable cost trend has shown a step change since 2007/2008 compared to 2010/2011 due to development and multi-supplier competition

• AAP ceramic media costs have reduced by more than 50% in that time,

• development of larger medias – 6 mm used in a few operations and emerging trend is to better quality medias; higher specific gravity

• Standard media test being developed

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Ceramic media – types of media

Relative cost

Zirconia, Yt/Ce

Zirconium silicate

Zirconia toughened alumina – ZTA

Alumina

Alumina silicates

US$/kg

> 2 0

15 - 20

5 - 10

4 - 7

2 - 4

2-4

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Thank You for listening

Questions?