STIRRED MILLING TECHNOLOGY

Transcription

1 STIRRED MILLING TECHNOLOGY

2 Xstrata Technology Important expertise in Grinding, Flotation, Smelting, Leaching & Refining Technology Centre Sudbury North America Vancouver Tankhouse Technologies Townsville South America Santiago Africa Johannesburg Australasia & Europe Brisbane Xstrata Technology Xstrata Process Support

3 Presentation Outline Technology Development Operating Principle Key Advantages Maintenance Aspects Case Studies

4 Technology Development Development driven by inability to efficiently treat fine grained minerals Broken Hill Late 1980s, Xstrata required 7 µm grind of Pb/Zn ore for new projects Conventional technologies previously tested, 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 0 40 micron McArthur River 0 40 micron

5 Technology Development Horizontal Bead Mills Technology existed in manufacturing (Netzsch) Small scale Batch operation Very expensive exotic media types Horizontal Bead Mill Technology Cross-over from manufacturing into minerals required: Much larger scale Continuous operation Ability to use cheap local media Design for easy maintenance Tower Mill Technology From AMIRA P336

6 Technology Development 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

7 Technology Development 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

8 Operation Layout DISCHARGE Product Separator Gearbox FEED SLURRY WITH MEDIA Typical Configurations: M MW motor M MW motor M kw motor Motor Shaft Bearings Shell Inside shell are rotating grinding discs mounted on shaft which is coupled to motor and gearbox. FEED SLURRY WITH MEDIA Gearbox Rotor SHELL SLIDES AWAY FOR MAINTENANCE Shaft Bearings Grinding Discs Motor

9 Operating Principle GRINDING MECHANISM & MEDIA RETENTION Shaft rotating at high speeds generating disc tip speeds ~ 20 m/s Multiple stages of grinding Impeller pumps liquid back into chamber to retain media Grinding Disks Displacement Body Product exit Shaft Grinding Chamber PATENTED PRODUCT SEPARATOR Recirculating grinding patterns of media occur between disks due to variation in velocity profile across disks Rotor Media centrifuged to outside of grinding chamber by high centrifugal force generated inside mill CLASSIFICATION ZONE

10 IsaMill in Action

11 Media Retention Patented PRODUCT SEPARATOR Generates G-Force of 60x Tip speed ~ 20 m/s Displacement Body Glass Bead Media Last Grinding Disc Rotor Rotor Fingers (Blurred)

12 Sharp size distribution

13 Media Addition Power Draw Control New Media Media Hopper Controller Screw Feeder with VSD Feeder Speed Motor Power Draw Setpoint Product Feed Slurry ISAMILL Motor Feed Feed Tank Feed Pump with VSD

14 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

15 Open Circuit - IsaMill Internals 8 grinding chambers in series no short circuiting Product separator retains media without fine screens GRINDING DISCS PRODUCT SEPARATOR

16 Open Circuit - Media Load High media filling in disc grinding zone ~ 80% - no short circuiting

17 Sharp Product Size Distribution KOC RoC Regrind Test - MT1 Media - Open Circuit Cumulative % Passing Narrowing Size Distribution with increased IsaMilling Feed 20 kwh/t 36.7 kwh/t 57.4 kwh/t kwh/t Minimal over-grinding Size (um)

18 Cosmos Nickel Mine Recently Installed M500 regrinding Rougher Conc Cosmos Isamill Feed and Product Product Feed % Passing Size (microns)

19 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

20 High Intensity - Step Change in Size Tower Mill Max 1.1 MW after 50 years 40 kw/m 3 Closed circuit with cyclones Media handling IsaMill Model M10,000 with 3.0 MW motor 300 kw/m 3 Open circuit with no cyclones Media system under mill platform

21 High Intensity Small Footprint 6.5 MW primary mill & 3.25 MW secondary mill Media handling system under IsaMill ISAMILL BALL MILL Mill Area (m 2 ) Media Handling (m2) Included 100 TOTAL AREA (m2) Installed Power (kw) MW M10,000 IsaMill Power per Unit Area (kw/m2) RELATIVE FOOTPRINT (%) 13 48% 6 100%

22 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

23 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

24 Direct Scale-Up Laboratory/Pilot results scaled directly to commercial size Uniform, homogeneous grinding mechanism. Zinc Ore Grinding Testwork Comparison Specific Energy (kwh/t) Test on M4 Lab Rig Full Scale - M3000 Mill Line of Fit P 80 (micron)

25 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

26 Energy Efficiency TYPICAL MILL CONDITIONS Media Charge Mill Speed Media Size BALL MILL < 45% (half empty mill) 20 rpm (slow mill) > 20 mm (media too big for efficient grinding) ISAMILL 80% > 230 rpm < 3.5 mm

27 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 Media Size (mm) No. Balls / m3 Surface Area (m2/m3) Ball Mill , Tower Mill , IsaMill 2 176,500,000 2,220 E d 3. v 2. SG STRESS INTENSITY d = media diameter v = media velocity SG = media density

28 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

29 Energy Efficiency - kwh/t 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 Media Size Tests Weller, Gao

30 Energy Efficiency - kwh/t 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 Cumulative % Passing KOC RoC Regrind Test - MT1 Media - Open Circuit Narrowing Size Distribution with increased IsaMilling Feed 20 kwh/t 36.7 kwh/t 57.4 kwh/t Sharp Classification Reduce Top Size, With Minimal Fines Production kwh/t Minimal over-grinding Size (um)

31 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

32 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 IsaMill TM testwork is always continuous with feed pumped through mill & product collected from discharge same as full-scale mill IsaMill TM 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 IsaMill TM 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

33 Tower Mill Testing - Segregation Effects Effect of the feed slurry volume of the 40-litreTower Mill for grinding #4 SAG01 cyclone overflow 20 Net Energy Consumption, kwh/t litres of feed slurry 50 litres of feed slurry Product P 80, microns

34 Energy Efficiency Tower Mill Comparison RESULTS OF TESTWORK ON MAGNETITE Signature Plot - P80: IsaMill TM vs Tower Mill P80 IsaMill Test 1 P80 IsaMill Test 2 P80 Tower Mill Test 1 P80 Tower Mill Test 2 Specific Energy (kwh/t) At P 80 of 35 µm: Tower Mill = 32 kwh/t IsaMill = 18 kwh/t ISAMILL USES UP TO 45% LESS POWER F 80 = 110 µm Size (µm) M4 IsaMill 4 litre mill, operating with 3.5 mm ceramic Keramax MT1 media Tower Mill 40 litre capacity operating with 12mm steel media

35 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

36 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

37 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 IsaMill TM user

38 Inert Media Media Types & Effect MEDIA TYPES Ceramics Inert Media Benefits compared to Steel: Steel media Fe hydroxides Silica sand Autogenous (the ore itself) Negative impact flotation/leach kinetics Precipitate/coat particle surface Smelter slag Fe forms complex with cyanide increased cyanide consumption Slag River Sand Ore

39 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

40 Inert Media vs Steel Media AMIRA P260 Improved recovery with inert ceramic media Improved recovery of fines steel media has significant negative effect on large surface area Effects of grinding medium and gas purging on arsenopyrite (FeAsS) flotation (Huang et al., 2006)

41 Impact of Inert Grinding - Chalcopyrite

42 Fines Flotation at Mount Isa Pb-Zn Recovery by size in the Zinc Retreat Circuit After Isamill Inert Regrinding to P80 = 7 microns Zinc Distribution in Feed Zn Recovery by Size 100.0% 50.0% 90.0% 45.0% Zinc Recovery in size fraction % 80.0% 70.0% 60.0% 50.0% 40.0% 30.0% 40.0% 35.0% 30.0% 25.0% 20.0% 15.0% Zinc Distribution in Feed % 20.0% 10.0% 10.0% 5.0% 0.0% C7 C6 C5/C4 C3-C1 38/53 75 Size fraction 0.0%

43 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

44 Horizontal Layout - Benefits Shell on wheels. Easy maintenance. Single component lifts Low breakaway torque Restart after crash stop is no problem Wide operating range. Continuous turn-down Horizontal configuration enables large scale designs up to 3.0 MW 3 models available to accommodate different capacities M10, to 3.0 MW motor M to 1.5 MW motor M to 500 kw motor M10,000 M3000 M1000

45 Isamill Layout

46 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+%

47 Maintenance Aspects Shell slides along hydraulically operated rails for maintenance access

48 Maintenance Aspects Typical Wear Component Life: Set of Disposable Grinding Discs ~ 6 months Disposable Shell Liner ~ 12 months Discs removed from shaft using overhead crane

49 Fabrication All mills trial assembled in Germany

50 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 IsaMill Technology can change the way plants are designed: Replace tower or ball mills Simplify flotation circuits Produce higher grades to smelters Horizontal Layout Simple maintenance Starts under full load

51 Case Studies Fine Grained ores for flotation : McArthur River George Fisher Mt Isa Open Cut Standard Regrinding Duties Coarse Main Stream Grinding

52 Myths about Fines flotation Fines don t float Fines need more reagent Fines need special flotation cells Fines need more flotation cells

53 How the Fines Myth Started... Liberated Fines : Intermediate : fast floating Recovery High surface area Need high collector and low depressant lower collector need, composites need depressant Coarse Particles Low liberation Size (microns)

54 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

55 Zinc Concentrate +C3 Size Fraction +16um

56 Fines flotation - a different perspective MRM grinds to P80 of 7 microns P50 is 2.5 microns 96% of recovered particles are less than 2.5 microns 85% recovery into high grade concentrate.. Fines do float!

57 McArthur River Lead/Zinc Bulk Con - P 80 7 micron, 5 x M3000 (1.1 MW)

58 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

59 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

60 Applying Fine Flotation Principals : Conceptual Stage Grind Circuit Fines performance when treated by themselves Intermediate and coarse behaviour Recovery Fines peformance when treated with coarse particles Size (microns)

61 View of IsaMill Regrinding Section

62 Mt Isa Pb / Zn Concentrator Flow Sheet 70um Primary Grind/Float 37um Secondary Grind / Prefloat Pb Ro Pb Ro / Scav Zn Ro Zn Ro / Scav Float Rod & Ball Milling Ball Milling Tailings Tailings Zn Columns 37% Zn Rec Zn Conc 33% Pb Rec Pb Conc 46% Pb Rec 3 x 1.1MW IsaMills Jameson Cell Pb Cleaners 12um Regrind / Float 2 x 1.1MW IsaMills Pb Conc 12um Regrind / Float Zn Cleaners 1 x 0.52MW Tower Mill 39% Zn Rec Zn Conc 3 x1.1mw IsaMills Zn Retreatment Ro Tailings Zn Retreatment Cl Zn Conc 7um Regrind / Float 6% Zn Rec

63 Zinc Recovery Performance of the Concentrator Plant Stabilisation & Plant Optimisation IsaMills commissioned October 1999 Second Wave +5% Zinc Recovery First Wave +5% Zinc Recovery Baseline Reduced grinding/flotation capacity, due to equipment relocation during construction. Apr May 1999 Jun Jul Aug Sep Oct Nov 1999 Dec Jan Feb 2000 Mar Apr May Jun Jul Aug Sep Oct 2000 Nov Month

64 IsaMills made more fines and increased fines recovery Zn Recovery vs Size - before and after IsaMilling 100 Whole circuit recovery, roughing and cleaning, including losses to lead concentrate Increased recovery in fine sizes Apr Moved particles from low recovery and low grade fraction to higher recovery and higher grade fines fraction Oct Net result - 10% recovery increase and 2% concentrate grade increase SIZE (microns)

65 100% 90% Recovery 50.0% 45.0% 100% 50.0% 80% 70% 40.0% 90% 45.0% Recovery 37 micron circuit 35.0% 80% 12 micron circuit 40.0% 60% 50% 40% 30% 20% 10% 0% Size Distribution C7 C6 C5/C4 C3/C2 C1/ um 4-8um 8-16um 16-30um 30-53um Size fraction 30.0% 25.0% 20.0% 15.0% 10.0% 5.0% 0.0% Zinc Recovery in size fraction % 70% 60% 50% 40% 30% 20% 10% 0% Size Distribution C7 C6 C5/C4 C3/C2 C1/ um 4-8um 8-16um 16-30um 30-53um Size fraction 35.0% 30.0% 25.0% 20.0% 15.0% 10.0% 5.0% 0.0% Combine for Overall Circuit Recovery 70um Primary Grind/Float Prefloat Pb Ro 37um Secondary Grind / Float Pb Ro / Scav Zn Ro Zn Ro / Scav 100% 50% Rod & Ball Milling Ball Milling Zn Columns Tailings 37% Zn Rec Zinc Recovery in size fraction % 90% 80% 70% 60% 50% 40% 30% 7 micron circuit 45% 40% 35% 30% 25% 20% 15% Tailings 3 x 1.1MW IsaMills 33% Pb Rec Jameson Pb Conc Cell Pb Cleaners 46% Pb Rec Pb Conc 12um Regrind / Float 12um Regrind / Float 2 x 1.1MW IsaMills Zn Cleaners 3 x1.1mw IsaMills 1 x 0.52MW Tower Mill Zn Retreatment Ro Zn Conc 39% Zn Rec Zn Conc Tailings 20% 10% 10% 5% Zn Retreatment Cl Zn Conc 0% C7 C6 C5/C4 C3-C1 38/ um 38-75um 4-8um 8-16um 16-38um Size fraction 0% 7um Regrind / Float 6% Zn Rec

66 Mt Isa Zinc Circuit Recovery by Size 100% 50% 90% Recovery 45% 80% 40% Zinc Recovery in size fraction % 70% 60% 50% 40% 30% Size Distribution 35% 30% 25% 20% 15% 20% 10% 10% 5% 0% 0.0% C7 C6 C5/C4 C3-C1 38/ um 38-75um 4-8um 8-16um 16-38um Size fraction

67 Impact of Fine Grinding for George Fisher Ore 8 MW of IsaMills and Stage Grind and Float led to : - 5% increase in lead recovery - 5% increase in lead concentrate grade - 10% increase in zinc recovery - 2 % increase in zinc concentrate grade And : - less reagents! - very small increase in flotation capacity - lower circulating loads - much simpler ciruit - same unit cost with 8MW additional grinding power

68 The Scientific Method. Describe mineral behaviour... - size by size - mineral by mineral -by liberation class Understand impact of - bulk properties - surface and solution chemistry Account for effect of - operating constraints - materials handling

69 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

70 Blackstar Ore Mineralogy

71 Lead Grade Recovery - Conventional vs IsaMills Pb Grade/Recovery Curve - ISA Lead-Zinc Transition Ore 80 Result : Approval of Open Cut in 2004, treatment commenced Mar Results with IsaMill Inert Grinding Pb Grade Conventional Circuit with Steel Grinding Pb Recovery

72 Anglo Platinum, South Africa

73 Anglo Platinum, South Africa Mainstream Inert Grinding F µm to P 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

74 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

75 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

76 Case Study Prominent Hill Float Feed Final Tails Roughers Jameson Scalper Cell IsaMill TM Densifying Cyclones 1 st Cleaners ISAMILL TM REGRIND CIRCUIT 2 nd Cleaners 3rd Cleaners Final Concentrate

77 Case Study Prominent Hill Jameson Cell in conjunction with IsaMill TM as scalper cleaner directly after regrinding Fast flotation device ideal to treat fine, fresh surfaced particles generated in IsaMill TM 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

78 Case Study Teck Cominco, Red Dog, Alaska Purchased 2 x M3000, 1.5 MW IsaMills TM 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 IsaMills TM 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

79 Upcoming IsaMill TM Commissioning Projects Somincor (Portugal) Cu / Zn Rougher concentrate feed (15 t/h) F80 = 45 µm, P80 = 8 µm 1 x 1.5 MW M3000 IsaMill TM 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 IsaMills TM Zn Rougher Concentrate feed (268 t/h) F80 = 125 µm, P80 = 25 µm 2 x 3 MW M10,000 IsaMills TM To start commissioning August 09

80 Primary Grinding Circuit IsaMill TM McArthur River Project Originally designed for fine grinding Mount Isa, McArthur River IsaMill TM 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 George Fisher, Mt Isa, Australia More primary grinding capacity required Rather than increase SAG mill capacity, evaluation showed more efficient alternative to use IsaMills TM With higher tonnage, coarser SAG mill product would be generated & treated directly in large 3 MW IsaMills TM

81 Primary Grinding Circuit IsaMill TM McArthur River Project Initial M20 trials results obtained in 2006 Results confirmed that grinding feed up to F 80 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 IsaMills TM - McArthur River, NT, Australia

82 Coarse Grinding at MRM M3000 Isamill treating a blend of Cyclone Underflow and some Cyclone Overflow Primary Cyclones Flotation Feed Ore stockpile Feeder SAG Mill 6.1mx7.32m EGL Allis 4MW Tower Mill 935kW IsaMill Screen

83 Coarse Grinding at MRM 100 Net Energy (kwhr/t) 10 1 IsaMill operating point at equivalent energy input to Tow er Mill IsaMill Testw ork P80 Size (m icrons) Tower Mill Operating Point

84 Coarse Grinding at MRM M3000 Isamill treating a blend of Cyclone Underflow and some Cyclone Overflow micron feed 100 Size Vs Energy for Feed of microns Net Energy [kwh 10 9 y = x R 2 = µm P80 Size [microns]

85 Coarse Grinding at MRM M3000 Isamill treating a blend of Cyclone Underflow and some Cyclone Overflow micron feed Size Vs Energy for Feed of microns Net Energy [kwhr/t] y = x R 2 = µm P80 Size [microns]

86 Primary Grinding Circuit IsaMill TM McArthur River Project 2 x M10,000 (3 MW) Primary Grinding IsaMills TM - commissioned late 2008 Installation & Commissioning, NT, Australia

87 IsaMill TM Technology Growth Cumulative Installed Power (MW) ORANGE M500 GREEN - M1000 BLUE - M3000 RED - M10,000 McArthur River Expansion George Fisher Red Dog Penasquito II (Goldcorp) Dominicana Gold Leinster Nickel (BHPBilliton) Boynton Somincor Penasquito I (Goldcorp) Anglo Platinum BRPM Anglo Platinum PPRust North UFG Anglo Platinum PPRust North Anglo Platinum Waterval Retrofit UFG Anglo Platinum Waterval Retrofit Anglo Platinum Amandelbult UG2 #1 Anglo Platinum Amandelbult Merensky Plant Anglo Platinum Amandebult UG2 #2 Anglo Platinum Amandebult UG2 #2 McArthur River Prominent Hill Anglo Platinum Waterval UG2 Anglo Platinum PPL-A/B Anglo Platinum WLTRP Anglo Platinum PPL-C Lonmin EP-C Centerra Gold Kumtor Phelps Dodge Morenci KCGM Fimiston KCGM Gidgi McArthur River 10 IsaMill TM M10,000 Mt Isa Pb Circuit Commercialisation Development Year Korea Zinc Climax Cosmos Nickel Oceana Caribou Phu Kham

88 ISAMILL GRINDING TECHNOLOGY Thankyou. Questions? /