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1 MMMA President’s Seminar Stilfontein, May 20 th 2011 “Fine grinding – UG2 processing” Chris Rule Head of Concentrator Technology Anglo American Platinum.

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Presentation on theme: "1 MMMA President’s Seminar Stilfontein, May 20 th 2011 “Fine grinding – UG2 processing” Chris Rule Head of Concentrator Technology Anglo American Platinum."— Presentation transcript:

1 1 MMMA President’s Seminar Stilfontein, May 20 th 2011 “Fine grinding – UG2 processing” Chris Rule Head of Concentrator Technology Anglo American Platinum

2 2 Agenda  Background  UG2 ore’s growing importance – challenges!  Stirred milling in AAP  Stirred Milling in the mining industry SA/worldwide  Latest trends

3 3 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

4 4 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

5 5 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 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

6 6 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

7 7 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 1 µm

8 8 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

9 9 Typical UG2 tailings PGM losses

10 10 Summarized AAP UG2 process flow MIG stirred Mill Feed Tank FAG/SAG primary mill Chrome split cyclone Silica ball mill Primary Rougher Chrome ball mill ROM FF/ Chrome Rougher Secondary Rougher 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)

11 11 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

12 12 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

13 13 Feed from the Mine Primary Milling Secondary Milling Sidestream Mainstream MIG Circuit 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 Cleaning Flotation High GradeHigh/Medium GradeLow Grade Bypass Smelters Stirred Milling MF2 PGM Flow sheet

14 14 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

15 15 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

16 16 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 ~2/3 rds UG2 ROM feed and dropping head grades POST MIG RESULTS

17 17 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

18 18 Chromite control – AAP view 4-fold increase in Cr 2 O 3 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

19 19 IsaMill installations at Anglo Platinum Waterval Concentrator MIG & UFG Amandelbult UG2 #2 Concentrator MIG & UFG Mogalakwena South Concentrator C section – the first MIG Mogalakwena South Concentrator A & B MIGs

20 20 Stirred milling - worldwide Growing acceptance of this technology in the mining industry, IsaMill TM 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

21 21 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

22 22 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

23 23 Rapid growth in IsaMill TM installations 10/22 Pb & Zn industry Au industryAustralia Anglo American Platinum Anglo American Platinum MIG and UFG IsaMill Projects 250 $ million investment

24 24 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 IsaMill TM application in 2006 at Mogalakwena South Concentrator AAP has 22 IsaMills and a further 4 in the project cycle currently

25 25 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 SEPARATOR GRINDING DISCS DISCHARGE RING Note – not a screen. Flow directional device Large Aperture – 12.5 mm (½ inch) Mill layout and design 2/22

26 26 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

27 27 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

28 28 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

29 29 Ceramic media – types of media Ceramic media classes Alumina Zirconium silicates Stabilised Zirconia Ce, Yt Glass Zirconia toughened alumina 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

30 30 Thank You for listening Questions?

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