MMMA President’s Seminar
Stilfontein, May 20th 2011
“Fine grinding – UG2 processing”
Chris Rule
Head of Concentrator Technology
Anglo American Platinum
1
Agenda
 Background
 UG2 ore’s growing importance – challenges!
 Stirred milling in AAP
 Stirred Milling in the mining industry SA/worldwide
 Latest trends
2
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
3
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
4
Stage milling and flotation
• At Waterval - 1987 first two
regrind mills; second two in 1990
• Merensky only processed in this
period
65.0
Final Grind (%-75um)
• Stage grinding introduced in late
80s-early 90s to improve
liberation and recovery
70.0
MF2 circuit
MIG stirred
Mill
60.0
-8mm
55.0
Ball
mill
Regrind
Ball mill
Primary
Rougher
Secondary
Rougher
Final tails
50.0
45.0
40.0
• Waterval first site, quickly
followed group wide and at all
new flow sheets employed from
1990s
•
5
UG2 from late 1980s and
Platreef exploited from 1993
J MM 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
1986
1987
1988
1989
1990
1991
9
90.0
89.0
88.0
87.0
Recovery (%)
• MF2 circuits critical for UG2
and Platreef due to liberation
size now much finer
86.0
85.0
84.0
83.0
82.0
81.0
80.0
J MM 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
1986
1987
1988
1989
1990
1991
Multi plant platform
•
•
•
•
•
•
•
•
•
•
•
•
•
•
6
Rustenburg - Waterval (620 ktpm)
Managed Operations
Rustenburg - Waterval UG2 (450 ktpm)
14 plants with total monthly
Rustenburg – WLTR (450 ktpm)
nameplate capacity of 3.5 million
Amandelbult – Merensky (320 ktpm)
tonnes ROM per month
Amandelbult - UG2#1 (220 ktpm)
In FY 2010 produced 1.74
Amandelbult - UG2 #2 (210 ktpm)
million ounces Platinum
Union - Mortimer UG2 (240 ktpm)
Union - Mortimer Merensky/UG2 (110ktpm)
Union - Mortimer Slag/UG2 (65 ktpm) Further production from JV and
Union – Ivan (110 ktpm)
shared mining operations, (7 plants).
Mogalakwena – MSC (385 ktpm)
Kroondal/Marakana – UG2, 3 plants
Mogalakwena – MNC (600 ktpm)
Bokoni, UG2 and Merensky 2 plants
Mototolo UG2 – (220 ktpm)
Modikwa UG2: BRPM Merensky/UG2
Unki MSZ – (120 ktpm)
UG2 Ore characteristics
Milling data 1999 to 2009
6.00
60
5.00
UG2 % of total processed
50
% reef type of total milled
• UG2 is the major ore source
for AAP and the industry in
South Africa
70
Platreef as % total processed
4.00
Built-up head grade gpt 4T
40
3.00
30
2.00
20
1.00
10
0
0.00
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
100%
80%
60%
Area %
1999
• UG2 and Platreef - complex
mineralogy and increasingly
more difficult to attain good
extractions
gpt PGM 4T
• Since late 90’s switch from
Merensky to UG2 and
Platreef, and now MSZ
40%
20%
0%
Feed
• Average PGM minerals
grain size finer; < 10 micron
in UG2 and greater
dissociation from sulphides
into gangue
7
Liberated
Attached to silicate
1 µm
Concentrate
Enclosed in BMS
Grain Boundary
Tailings
Attached to BMS
Enclosed in oxide
Tailings-10
Tailing+10
PGM/BMS associated
Attached to oxide
Tailings +53
Enclosed in silicate
Ore mineralogy - UG2
UG2 ore typically contains finer
PGM mineralization and often a
greater proportion is dissociated
from larger grain sulphides
5 µm
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
PGM
Silicate
The
recovery
potential
at
conventional grinds will deteriorate
unless circuits change
BMS
10 µm
8
Typical UG2 tailings PGM losses
9
Summarized AAP UG2 process flow
UG2 processing – “MF2” with split regrind and flotation
Primary
Rougher
ROM
FAG/SAG
primary mill
Chrome split
cyclone
Feed
Tank
Silica ball
mill
MIG stirred Mill
Secondary
Rougher
Final tails
Chrome ball
mill
FF/ Chrome
Rougher
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)
10
Stirred Milling – origins in AAP
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
11
Stirred Milling – AAP’s timeline
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:
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
12
Stirred Milling MF2 PGM Flow sheet
Mainstream Inert Grinding (MIG) is designed to
improve recoveries by optimising liberation in an
‘inert’ media environment
Ultra-Fine Grinding (UFG) reduces the mass pull
through better liberation, surface cleaning and
improving the selectivity between gangue and
value minerals
MIG Circuit
Mainstream
Feed from
the Mine
Primary
Milling
Flotation
Tailings
Secondary
Milling
Flotation
Bypass
Sidestream
UFG Circuit
Cleaning
High Grade
Flotation
Bypass
High/Medium Grade
Smelters
13
Flotation
Low Grade
Tailings
Stirred Milling – scale up
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
14
Site recovery increasing
93
Waterval Site Platinum % Recovery
92
91
•
Amandelbult Site Platinum % Recovery
Linear (Waterval Site Platinum % Recovery )
•
Linear (Amandelbult Site Platinum % Recovery)
90
Post commissioning of the
MIG IsaMills at Rustenburg
and Amandelbult
Step change in
metallurgical performance!
89
88
•
Platinum recovery
improvements
– Waterval UG2
> 5%
– Amandelbult UG2 ~ 5%
•
Site recovery includes
tailings scavenging
87
86
85
84
83
15
Tails values - historical low
4E tailings values
1.00
•
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
Waterval 4E tails
0.90
Amandelbult 4E tails
0.80
0.70
0.60
0.50
0.40
0.30
0.20
YTD
YTD
YTD
YTD
YTD
2005
2006
2007
2008
2009
15 months
2010/2011
POST MIG
RESULTS
16
best 6
months
UFG stirred milling
Product
grade &
recovery
shift
•
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
•
17
Benefit due to better liberation
but also due to intense surface
attritioning action in inert
grinding environment
Chromite control – AAP view
18
Not a smelter problem!
– must be solved in the
Concentrators
10
Circuit configuration
0.0
0
Blending – Platreef, MSZ
and Merensky
Cr2O3
UG2 mined of total output
30 per. Mov. Avg. (Cr2O3)
UG2 mined of total output (%)
0.5
2009
20
2008
1.0
2007
30
2006
1.5
2005
40
2004
2.0
2003
50
2002
2.5
2001
60
2000
3.0
1999
Cr2O3 in concentrate feed to Waterval Smelter (%)
4-fold increase in Cr2O3 in
furnace feed over past decade!
New technology is the only
solution and is available now
 UFG stirred milling
Column flotation technology
IsaMill installations at Anglo Platinum
Waterval Concentrator
MIG & UFG
Mogalakwena South
Concentrator A & B MIGs
19
Amandelbult UG2 #2
Concentrator MIG & UFG
Mogalakwena South Concentrator
C section – the first MIG
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
20
Stirred mills in mining
PtMile tails – SMD 355 & Deswik 2000 L 2 sets
Sylvania – SMD 185 & SMD 18.5 – 8 sets
Impala – SMD 355 2 sets tails scavenging
21
PGM industry & stirred milling
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
Operator
Operation
PGM Concentrators
Anglo Platinum/JVs
WLTR
number of stirred
mills
type
installed power
kW
application
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
Boynton
1
IsaMillTM M3000
1500
MIG
UFG
Platmin
PGM Tailings retreatment
Impala
Rustenburg TRP
2
Metso SMDTM 355
710
Platinum Mile
Paardekraal TRP
2
Metso SMDTM 355
710
UFG
Paardekraal TRP
2
Deswik-2000 litre
1065
UFG/MIG
Chromite tailings retreatment
Aquarius/JV
RK1 chromite tails
1
MIG
Steelpoort
2
Deswik-1000 litre
Metso SMDTM 185/18.5
500
Sylvania
203.5
UFG/MIG
Lannex
1
Metso SMDTM 185/18.5
185
UFG/MIG
Lannex
1
75
MIG
Millsell
2
Kings
Metso SMDTM 185/18.5
203.5
UFG/MIG
Brits chrome TRP
1
Deswik-500 litre
220
MIG
Tharisa
22
Rapid growth in IsaMillTM installations
140
Climax
Penasquito II (Goldcorp) Red Dog
Somincor
Dominicana Gold
Leinster Nickel (BHPBilliton)
Boynton
Penasquito I (Goldcorp)
GREEN - M1000
BLUE - M 3000
RED - M 10,000
130
Cumulative Installed Pow er (M W)
120
Anglo Platinum BRPM
Anglo Platinum PPRust North UFG
110
Anglo American Platinum MIG
and UFG IsaMill Projects
100
Anglo Platinum Waterval Retrofit UFG
Anglo Platinum Waterval Retrofit
250 $ million investment
90
Anglo
American
Platinum
80
Anglo Platinum Amandelbult UG2 #1
Anglo Platinum Amandelbult Merensky Plant
Anglo Platinum Amandebult UG2 #2
70
Anglo Platinum Amandebult UG2 #2
McArthur River
60
50
Australia
Oceana
Caribou
Anglo Platinum Waterval UG2
Au industry
40
Pb & Zn industry
Anglo Platinum WLTRP
Phu Kham
Anglo Platinum PPL-C
Centerra Gold Kumtor
Lonmin EP-C
30
10
Prominent Hill
Anglo Platinum PPL-A/B
20
McArthur River Expansion
George Fisher
McArthur River
Mt Isa Pb Circuit
0
1992
23
Anglo Platinum PPRust North
1994
IsaMill
1996
TM
Commercialisation
1998
Phelps Dodge Morenci
KCGM Fimiston
KCGM Gidgi
2000
M10,000
Development
2002
2004
2006
2008
2010
10/22
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
24
Mill layout and design
•
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
GRINDING DISCS
PRODUCT SEPARATOR
DISCHARGE RING
Note – not a screen. Flow directional device
Large Aperture – 12.5 mm (½ inch)
25
2/22
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
26
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
27
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
28
Ceramic media – types of media
Relative cost
US$/kg
>20
15 - 20
Zirconia, Yt/Ce
Zirconium silicate
 5 - 10
Zirconia toughened
alumina – ZTA
4-7
Alumina
2 - 4
 2-4
29
Alumina silicates
Thank You for listening
Questions?
30