Rebecca Fleming

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    Improving Fine (

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    Introduction to Northparkes Mine

    Fine Copper Recovery at Northparkes

    Magnetic Agglomeration

    Experimental Design & Analysis

    Study Conclusions

    Questions

    Presentation Overview

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    Copper & gold mine

    Joint venture 80% Rio Tinto & 20%

    Sumitomo Group

    Located ~ 390 km west of Sydney

    Underground and open cut ore sources

    Northparkes Mine

    Sydney

    Northparkes Mine

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    Copper Minerals: predominately chalcopyrite (CuFeS2

    ) & bornite (Cu5

    FeS4

    )

    Head grade: 0.83% Cu, 0.44 g/t Au

    Recovery targets: 89.7% Cu, 79.0% Au. Grade targets: 34.4% Cu, 16.8 g/t Au

    Facts about Northparkes Mine

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    Northparkes Flowsheet

    Ore processed through 2 parallel modules.

    Planned milling rates: Module 1 245 t/h, Module 2 423 t/h

    ML04

    (5500x9400)

    CY03 A-D

    (20" CAVEX)

    HP13

    PP064/65

    (12/10 F-AH)

    CY04 A-O

    (15" CAVEX)

    Flash Float

    Rougher

    (Skimair)

    Flash Float

    Cleaner

    (Outokumpu 5)

    To Con

    Pump

    To Flotation Circuit

    PP068 SUMP

    (65VD-GPS)

    To Primary Hopper

    PP066/67

    (14/12 FF-AH)

    FT45

    FT46

    -

    Ball Charger

    BC02

    Magnet(MA02)

    CV10 Weightometer

    Feeders

    FE06-09

    Oversize

    Crusher

    CR03

    ML03

    (8500x4300)

    SV06

    Svedala(2400x6100)

    CV11

    CV12

    Ore

    Stockpile

    Ore

    Stockpile 2Weightometer

    Apron

    Feeder

    AF01

    Ball Charger

    Hopper

    HP15

    Trommel

    TL04

    Metal

    DetectorCV21

    MODULE 2 RECLAIM

    (321) & GRINDING(330) CIRCUIT

    SCATS

    CV332

    CV334

    CV329

    Splitter

    CV330

    PP091

    (Frother)

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    Northparkes Flowsheet

    Ore processed through 2 parallel modules.

    Planned milling rates: Module 1 245 t/h, Module 2 423 t/h

    CY06 A-H

    15" Krebbs

    ML06

    TK36

    Conditioner 1 TK37

    Conditioner 2

    1st Roughers

    (Dorr Oliver)

    FT15-16

    1st Scavengers

    (Dorr Oliver)

    FT19-20

    Cleaner

    Jameson

    Cell

    Jameson

    Cell

    Recleaner

    TK57/58

    Cleaner-Scavenger Feed

    Conditioner

    Cleaner-Scavengers

    (Dorr Oliver)

    FT23-26

    MODULE 2FLOTATION (340)

    CIRCUIT

    To Concentrate Thickener

    To Tailings

    Thickener

    From

    Grinding

    Circuit

    Flash Float Con

    PP223 SUMP

    (65VD-GPS)

    To HP41

    Trommel

    TL06

    HP41

    PP222

    (12/10 F-AH)

    PP080

    (8/6 E-AH)

    HP25

    FT27

    (8 Downcomers)

    FT28

    (3 Downcomers)

    AG30/31

    PP075

    (8/6 E--AH)

    BL01-03

    Blowers

    TO FLOAT CELLS

    PP079

    (12/10 E-M)

    HP12

    AG21

    AG22

    PP082

    (4RV-AF)

    PP076

    (6/4 D-AH)

    HP11

    HP26

    PP081

    (6/4 D-AH)

    PP115

    (NaHS)

    PP089/90

    (Frother)

    PP110

    (Collector)

    PP103

    (Promoter)

    PP112

    (Collector)

    Optional

    Optional

    Optional

    Optional

    NONC

    CV453

    CV454

    CV457

    CV459

    2nd Roughers

    (Dorr Oliver)

    FT17-18

    2nd Scavengers

    (Dorr Oliver)

    FT21-22CV452

    CV451CV450

    TK50

    Pre-Float

    PP69CV715

    NCNO

    Proflote Units

    To Hopper 14

    CY05 Feed

    NC

    NO

    NC NO

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    Fine Copper Recovery

    +150+106+75+53

    +38+20+11-11

    Mass Distribution

    Cu Dis tribution

    0

    5

    10

    15

    20

    25

    30

    35

    40

    %R

    etained

    Size Fraction (m)

    Mean Copper and Size Distribution of Northparkes Module 1 final tail (2009)

    Significant copper and mass losses in

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    Magnetic Agglomeration (1 of 2)

    ProFloteTM installed at Northparkes

    Selective agglomeration of paramagnetic

    minerals

    Paramagnetic minerals become magnetised

    when exposed to a strong magnetic field

    Agglomeration of magnetised paramagnetic

    minerals occurs when there is sufficientmagnetic attraction

    ma VVVV rt

    Vt = Total energy of attraction

    Va= London van der Waals energy (attractive)

    Vr= Electrostatic energy (repulsive)

    Vm= Magnetic energy (attractive)

    *

    *Sourced from: Svoboda (1987) Magnetic Methods for the Treatment of Minerals, Elsevier Ltd., Amsterdam, Netherlands.

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    Magnetic Agglomeration (2 of 2)

    Agglomeration (magnetic attraction energy) dependent on:

    mineral magnetic susceptibility,

    mineral particle size, and

    distance between minerals and magnetic induction.

    Mineral Reported magnetic susceptibility

    (M3kg-1x10-9)*

    Chalcopyrite 1596.0

    Bornite 101.0

    Quartz -5.7

    Pyrite 1.0 5.0

    Gold -0.15

    *Sourced from: Svoboda (1987) Magnetic Methods for the Treatment of Minerals, Elsevier Ltd., Amsterdam, Netherlands.

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    Magnetic Conditioning Previous Results*

    Size Fraction Change in Cu Recovery (%)with magnetic conditioning

    Level of StatisticalConfidence (%)

    38 m +1.2 Very low

    Total sample +1.4 96.0

    ProFloteTM installed in Module 2 flotation feed stream in 2005

    Randomised block statistical plant trial to assess its effectiveness

    ~6 months to complete trial

    No difference in copper concentrate grade with magnetic conditioning

    *Sourced from: Rivett, T., Wood, G. and Lumsden, B. (2007) Improving Fine Copper and Gold Flotation RecoveryA Plant

    Evaluation. Proceedings of the Ninth Mill Operators Conference, The Australasian Institute of Mining and Metallurgy, Melbourne,

    Australia. pp 223 228.

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    Measuring Agglomeration Unrelated flotation study at Northparkes (December 2009) discovered

    agglomeration could be observed using laser diffraction

    Laser diffraction is an optical size distribution technique

    Different sized particles scatter light, from a laser beam, at different angles

    and intensities

    Images sourced from: Malvern Instruments Inc, 2010. Available from http://www.malvern.com/processeng/processes/classification

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    Measuring Agglomeration Stage 1

    0.0

    0.5

    1.0

    1.5

    2.0

    2.5

    3.0

    3.5

    4.0

    4.5

    5.0

    0.1 1.0 10.0 100.0 1000.0

    Volume%InSizeClass

    Particle Size (m)

    0.0

    0.5

    1.0

    1.5

    2.0

    2.5

    3.0

    3.5

    4.0

    4.5

    5.0

    0.1 1.0 10.0 100.0 1000.0

    Volume%InSizeClass

    Particle Size (m)

    Magnetic ConditioningNo Magnetic Conditioning

    Cleaner Feed (before sonication) average Cleaner Feed (after sonication) average

    Natural agglomeration

    % agglomeration estimated as change in % volume (of a size fraction) before and

    after sonication

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    Measuring Agglomeration Stage 2

    ProFloteTM installed in Module 1 flotation feed stream early 2010

    Rather than traditional plant trial, laser diffraction technique used to estimate

    degree of agglomeration. Test work completed within 1 week.

    Paired t-test analysis showed statistically significant increase in particle size

    with magnetic conditioning

    Mean Results

    Size Fraction Copper Minerals (%) Agglomeration (%)*

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    Correlating Magnetic Agglomeration with

    Copper Recovery

    Traditional on/off plant trial not conducted unstable feed conditions during study Previous trial showed 2.1% increase copper recovery for

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    Conclusions

    Agglomeration of paramagnetic copper minerals observed in cleaner feedstream following magnetic conditioning of flotation feed

    Agglomeration occurring for copper minerals

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    Paper Amendments

    Page 224, Procemin 2010 Seminar ProceedingsCorrelation of Magnetic Agglomeration with Copper Recoverysection

    Rivett et al [8] showed a 2.1% increase in copper flotation recovery for the

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    Questions

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    Acknowledgements

    David Rahal, Technical Director, Knelson (Deswik) Milling Solutions Inc

    Northparkes Mines, Rio Tinto

    Professor G Jameson

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    Magnetic Agglomeration (2 of 2)

    Agglomeration (magnetic attraction energy) dependent on:

    mineral magnetic susceptibility,

    mineral particle size, and

    distance between minerals and magnetic induction.

    *Sourced from: Svoboda (1987) Magnetic Methods for the Treatment of Minerals, Elsevier Ltd., Amsterdam, Netherlands.

    Vm = magnetic energy (attraction)o = magnetic permeability of a vacuum

    1, 2 = volume magnetic susceptibilities of the particles

    b1, b2 = radius of the particles

    H = magnetic field strength

    h = distance between the surface of the particles

    3

    21

    23

    2

    3

    121

    )(9

    )8(

    bbh

    HbbV

    o

    m

    *