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Current Developments in the Hydrometallurgical

Treatment of Copper Ores and Concentrates

The Hydrometallurgical

Treatment of Copper Concentrates

David Dreisinger

University of British ColumbiaVancouver, Canada


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Copper Ore/Concentrate Treatment

Focus on Sulfate Processes

Variety of Process Options Available

Key Factors Copper Leach Extraction

Iron Precipitation

Precious Metal Recovery Sulfur Deportment

Cost!


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Process Options

Copper Leaching Issues;

Copper leaching controlled by copper

mineral leach kinetics Chalcopyrite passivates under mild

conditions

Liquid sulfur wets unreacted minerals andstops leaching


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Chalcopyrite Passivation

Eh pH Diagram Shows Many Phases

between CuFeS2 (solid) and

CuSO4(aqueous)Chalcopyrite Passivates by an Iron-

Deficient Copper Sulfide (CuSn) in

Sulfate Based Leaching Processes


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Cu-Fe-S-H2O Diagram


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Strategies for Avoiding Passivation

Leach at potential/pH that avoids passivation.

Add silver to avoid copper polysulfide (tooexpensive)

Fine grind to P80 of less than 10 m (mineralleaches before passivation)

Use high temperature (+200 C) or aggressiveconditions (transpassive)

Add nitrogen species to catalyze oxidationand overcome passivation

Use chloride instead of sulfate

Use bacteria (thermophiles) that avoid

passivation


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PROCESS TEMP PRESSURE P80 Special S Yield

(C) (ATM) (m) (%)

ACTIVOX 110 12 7 70

ALBION 85 1 7 50

ANGLO-UBC 150 12 7 SURFACTANTS 70BIOLEACH 45 1 7 MESOPHILES 0

BIOCOP 85 1 37 THERMOPHILES 0

CESL 150 12 37 12 g/L Cl 90

DYNATEC 150 12 37 COAL + RECYCLE 60

GALVANOX 85 1 37 VARIOUS 95

MT GORDON 90 8 100 CHALCOCITE

PLATSOL 225 30 15 10 g/L NaCl 0

SEPON-ATM 85 1 100 CHALCOCITE

SEPON-AC 225 30 100 PYRITE 0TOTAL POX 225 30 40 0

SULFATE PROCESS OPTIONS FOR CHALCOPYRITE LEACHING

WITH TYPICAL PARAMETERS


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Chloride Based Processes

Chloride Leaching Under Atmospheric T and PConditionsAvoid Passivation

INTEC Copper Process Chloride Leach for Copper, Purification, Direct Electrowinning of

Copper as Dendrites

Hydrocopper Process (Outokumpu) Chloride Leach for Copper, Purification, Precipitation of Copper

(I) Hydroxide, Reduction of Hydroxide to Metal

Sumitomo Copper Chloride Process Chloride Leach of Cu/Fe, Cu SX with TBP, EW from Chloride,

Purification and EW of Fe

Nitrogen Species Catalyzed Processes

Nitrogen species (nitrate/nitrite) are catalysts for

oxidation of sulfur/sulfides and can be used to overcomepassivation.


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Chalcopyrite Oxidation and Sulfur

Elemental Sulfur Reaction Product

4CuFeS2 + 5O2(g) + 10H2SO4 =

4CuSO4 + 2Fe2(SO4)3 + 10H2O + 20S

(0.63 t O2/t Cu leached)

Sulfate Sulfur Reaction Product4CuFeS2 + 15O2(g) + 2H2O =

4CuSO4 + 2Fe2(SO4)3 + 2H2SO4

(1.89 t O2/t Cu leached)


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Sulfur Chemistry

Sulfur is formed from sulfide minerals

during leaching

Three temperature regimes

Low T: < 119.3 C SOLID (S8)

Medium T: 119.3 C to 159 C LIQUID

(S8)

High T: +159 C LIQUID/POLYMER (Sn)


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LOW T Leaching

Elemental sulfur forms porous product

layer

Kinetics can be slow due to diffusionthrough sulfur product layer


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Medium Temperature Leaching

Molten sulfur is dispersed by addition of

a sulfur dispersant/surface active agent

Lignin sulfonate and Quebracho are twocommon agents.

Sulfide mineral becomes sulfophobic

and hydrophilic

Sulfur liquid droplets are dispersed


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Apparatus for interfacial measurement

Lightsource

Lens Sapphirewindow

Adjustableholder

Opticalglass cell

Glass tip

Thermowell

Screw-drivesyringe

Plunger

Stainless steel bomb

Gas inlet

Pressure gauge

Outlet for gas bleeding

Sapphirewindow

Lens LensDigitalcamera

Adjustable holder

Mineralsample

Opticalglass cell

Glass tip

Liquor

sulfur


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Surfactant-free

0.05 g/L lignin sulfonate 0.1 g/L lignin sulfonate

0.05 g/L Quebracho

0.5 g/L lignin sulfonate

0.1 g/L Quebracho 0.5 g/L Quebracho

Sulfur Droplets in Acid Solution (150 C)


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Concentration / g L-1 0 0.05 0.1 0.2 0.3 0.4 0.5

Lignin sulfonate / mN m-1 55 43 35 31 29 29 29

Quebracho / mN m-1 55 45 38 37 37 37 37

Calculated Sulfur/Aqueous

Interfacial Tensions (SA)

C t D l t i th H d t ll i l


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0.05 g/L lignin sulofnate 0.1 g/L lignin sulofnate 0.5 g/L lignin sulofnate

0.05 g/L Quebracho 0.1 g/L Quebracho 0.5 g/L Quebracho

Surfactant-free

Sulfur Droplets in Acid Solution on

Chalcopyrite Mineral Surface (150 C)



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Concentration / g L-1

0 0.05 0.1 0.2 0.3 0.4 0.5

Lignin sulfonate / 76 142 152 155 156 157 158

Quebracho / 76 155 157 158 159 160 161

Contact Angles ()

Wa = SA(1+cos())

Concentration / g L -1 0 0.05 0.1 0.2 0.3 0.4 0.5

Lignin sulfonate / mJm-2

68.3 9.1 4.1 2.9 2.5 2.3 1.9

Quebracho / mJ m-2

68.3 4.3 3.0 2.7 2.4 2.2 2.0

Work of Adhesion (Wa)



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Iron Precipitation

Dissolved iron will be oxidized andprecipitated as ferric hydroxide (undesirable),

jarosite, goethite or hematite

Goethite forms at less than 140 C withhematite forming above 140 C

Jarosite can form over wide temperaturerange

Basic ferric sulfate processes (Sepon)precipitate iron at high free acid and high T(220 C). Iron forms basic ferric sulfateswhich then re-dissolve at atmospheric T+P.



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Precious Metal Recovery

Au may be recovered by cyanidation of copper leachresidues.

However if S present then form SCN and increase

the cost of Au recovery.Ag often forms Ag-jarosite under copper leaching

conditions. May have to use lime boil to decomposeAg-jarosite prior to cyanidation.

Alternative strategy to use other reagents (eg. S2O3

2-

,SCN- or Cl-/Br-)

PGM Recoveries difficult from residues but possibledirectly (PLATSOL)



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S Deportment and Impurities

S oxidation forms sulfuric acid

Sulfuric acid may be a by-product as a weak

sulfuric acid solution (economic credit)Sulfuric acid neutralization consumes

limestone or lime (expense).

Impurities are generally removed by

oxidation/pH adjustment as part of the leach

or iron residue.

C rrent De elopments in the H drometall rgical


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Process Examples

GALVANOX

Anglo American Corporation/University

of British Columbia Process

PLATSOL

SEPON Copper Process



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GALVANOX

Process developed by David Dixon and

Alain Tshilombo of University of British

ColumbiaAtmospheric leaching of chalcopyrite

concentrates under mild, galvanic

conditions to avoid passivationFollowing slides from David Dixon



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Atmospheric Leach (~80 C)

No microbes

Pure sulphate medium (no chloride)

No fine grinding

Generates elemental sulfur (> 95%), low oxygen demand

No surfactants

Selective for chalcopyrite over pyrite (can cost-effectively treat low

grade concentrates down to 9% copper or less) Complete copper recovery, typically in less than 12 hours, and

sometimes in as little as 4 hours

Fully compatible with conventional SX-EW

Conventional materials of construction

GALVANOX FEATURES



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GALVANOX takes advantage of the galvanic effect between

chalcopyrite and pyrite.

Chalcopyrite is a semiconductor, and therefore corrodes

electrochemically in oxidizing solutions.

In ferric sulphate media, the overall leaching reaction is as follows:

CuFeS2 + 2 Fe2(SO4)3 CuSO4 + 5 FeSO4 + 2 S0

This reaction may be represented as a combination of anodic and

cathodic half-cell reactions:

Anodic: CuFeS2 Cu2+ + Fe2+ + 2 S0 + 4 e

Cathodic: 4 Fe3+ + 4 e 4 Fe2+

GALVANOX CHEMISTRY



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UNASSISTED CHALCOPYRITE LEACHING

Cu2+

Fe2+

4 Fe3+

4 Fe2+

So

4 e-

CuFeS2

Anodic Site Cathodic Site



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UNASSISTED CHALCOPYRITE LEACHING



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Typically, chalcopyrite surfaces are passivated (i.e., they

become resistant to electrochemical breakdown) in ferric sulfate

solutions at even modest solution potential levels.

It is widely held that this results from the formation of some sortof passivating film on the mineral surface that most likely

consists of an altered, partially Fe-depleted sulfide layer.

Because of this, most investigators have assumed that it is the

anodic half-cell reaction that limits the overall rate of leaching.

However, we discovered that it is primarily the cathodic half-cell

reaction (i.e., ferric reduction) that is slow on the chalcopyrite

surface.

GALVANOX CHEMISTRY



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The presence of pyrite facilitates chalcopyrite leaching by

providing an alternative catalytic surface for ferric reduction in

electrical contact with the chalcopyrite

This essentially eliminates cathodic passivation of chalcopyrite inferric sulfate solutions.

Also, by ensuring that chalcopyrite oxidation is rapid relative to

ferrous oxidation, the solution potential is maintained at a level

low enough to prevent anodic passivation of the chalcopyrite

This also prevents anodic breakdown of the pyrite, which

remains more or less completely inert.

GALVANOX CHEMISTRY



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GALVANICALLY-ASSISTED

CHALCOPYRITE LEACHING

Cu2+

Fe2+

So

Py

Py

Cp

4 e-4 e-

4 Fe3+

4 Fe2+

Anodic SiteCathodic Site



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GALVANICALLY-ASSISTED

CHALCOPYRITE LEACHING

Partially leached particle Completely leached particles



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The ferric required for GALVANOX leaching is regenerated in situ with

oxygen gas

Ferric leaching of chalcopyrite:

CuFeS2 + 2 Fe2(SO4)3 CuSO4 + 5 FeSO4 + 2 S0

Oxidation of ferrous with dissolved oxygen gas:

4 FeSO4 + O2 + 2 H2SO4 2 Fe2(SO4)3 + 2 H2O

Overall leaching reaction:

CuFeS2 + O2 + 2 H2SO4 CuSO4 + FeSO4 + 2 S0 + 2 H2O

GALVANOX CHEMISTRY



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CHALCOPYRITE CONCENTRATE 35% Cu

Effect of pyrite addition (50 g con, 65 g acid, 470 mV, 80 C)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 4 8 12 16 20 24

Time (h)

CuRecovery

Py = 150 g (K5)

Py = 100 g (K9)

Py = 50 g (K6)

Py = 25 g (K10)

Py = 0 g (K1)



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0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0 4 8 12 16 20 24

Time (h)

CuRecovery

Galvanox Leaching

No Pyrite

CHALCOPYRITE CONC 2 23.6% Cu

Effect of pyrite addition (30 g con, 120 g Py, 30 g acid, 480 mV, 80 C)



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Stage Operating

Hours

Minimum Cu

Recovery (%)

Maximum Cu

recovery (%)

Average Cu

Recovery (%)

Plant Setup 0 -125 56.8 93.4 82.1

100% Recycle40 hrs

residence time

125-325 92.7 97.1 95.3

100% Recycle

20 hrs

residence time

325-405 88.4 95.4 91.6

200% Recycle20 hrs

residence time

405-464 96.6 97.9 97.3

Entire run

excluding plant

setup

125-464 88.4 97.9 94.6

CONTINUOUS PILOT PLANT RESULTS



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p y g


Anglo American Corporation/University of

British Columbia Process

Chalcopyrite concentrates are finely

ground (


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p y g


Copper Extraction as a Function of Initial Particle Size

150 C Leaching of Chalcopyrite Concentrate with Surfactant Addition

50.00

55.00

60.00

65.00

70.00

75.00

80.00

85.00

90.00

95.00

100.00

0 0.5 1 1.5 2 2.5 3 3.5 4

Time (hr)

CopperExtraction(%

)

5.28 um

10.01 um

13.04 um

17.93 umFiner Size



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p y g


Freeport-McMoRan Developments in

Copper Concentrate Leaching

John O. Marsden and John C. Wilmot

Freeport-McMoRan Mining Co.

Selected Slides from Copper 2007 Short Course,

Toronto, August 2007



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p y g


Morenci MT-DEW-SX Flowsheet

PLV Conditions:

~160 C

200 psi O2 overpressure

LE Added to PLV

Slurry

Formation

Concentrate

1,000 mtpd

PressureLeaching

Flash

Let Down

Solid/Liquid

Separation

Neutralization

Tailings

Disposal

Gold/Silver

Bullion

Water

(optional)

Super Fine

Grinding

*Tank includes vat or agitated

or stirred leaching vessel

Lime

Cathode

Copper

Heap/Stockpile/Tank*

Leaching

Solution

Extraction

ElectrowinningSPLS

Lean

Bleed

Coolant

Streams

WPLS

Precious Metals

Leaching/Recovery

Lean

to PLV

Flow (m3/hr)

Cu (g/L)

H2SO4 (g/L)

Fe (gpl)

24

33

1901.8

113

110

22

1.9

153

4.7

1.5

1.1

Feed

Solids

Solid/LiquidSeparation/Wash

Solids

Water

LEGEND:



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p y g


Morenci Concentrate Leach Plant



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p y g


PLATSOL

PLATSOL Process Simple process for one-step dissolution of base

and precious metals

Add 5-10 g/L Chloride to AC solution

Invented at Lakefield Research for BulkConcentrate Treatment

Tested via Batch and Continuous Autoclave

Programs at Lakefield High levels of base (+95-99%) and precious

metals (90-95%) recovery



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Pressu re Oxidat ion : Convent ional and

PLATSOL Metal Extractions (220 C)

Element Conventional PLATSOL**

Cu 99.3 99.6

Ni 95.9 98.9

Co >92 96

Fe 11.5 11.5

S 91.5 91.5

Pt ~0 96Pd 61.1 94.6

Au ~0 89.4

** ACTUAL PILOT PLANT RESULTS FROM SGS LAKEFIELD



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Autoclave Leaching Base Metals

ChlorideAssisted Total Pressure OxidationChalcopyrite Oxidation/Iron Hydrolysis:

CuFeS2 + 4.25O2 + H2O = CuSO4 + 0.5Fe2O3 +H2SO4

Pyrite Oxidation:

FeS2 + 3.75O2 + 2H2O = 0.5Fe2O3 + 2H2SO4Pyrrhotite Oxidation

Fe7S8 + 16.25O2 + 8H2O = 3.5Fe2O3 + 8H2SO4Nickel Sulfide Oxidation:

NiS + 2O2 = NiSO4Basic Ferric Sulfate Formation:

Fe O + 2H SO = 2Fe OH SO + H O



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Autoclave Leaching Precious Metals

Gold Oxidation/Chlorocomplex Formation:Au + 0.75O2 + 4HCl = HAuCl4 + 1.5H2O

Platinum Oxidation/Chlorocomplex

Formation:

Pt + O2 + 6HCl = H2PtCl6 + 2H2O

Palladium Oxidation/Chlorocomplex

Formation:

Pd + 0.5O2 + 4HCl = H2PdCl4 + H2O

Temperature of 220 to 230 C.



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Base and Precious Metal Recovery

Copper Copper Solvent Extraction and Electrowinning to

Produce LME Grade Copper Metal Cathode

Nickel/Cobalt Variety of Processes Possible

Mixed Hydroxide Precipitation of Nickel and Cobalt

Nickel and Cobalt Hydroxide Refined Off Site

SX-EW or SX-Hydrogen Reduction to Metal

Au-PGM Precipitate under reducing conditions to make high

value precipitate for refining



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Bulk Concentrate

Regrinding

PLATSOL

PGMs NaSH Precip

Cu SX/EW

Bleed

(Ni-Co recovery)

Leach Residue

NaCl

PGM Conc

SL



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Applications to Other

Cu/Ni/PGM ConcentratesConcentrate Types

ElementsD F G H I J K L M

Cu % 5.8 12.0 4.2 2.4 5.5 3.9 0.9 0.2 0.7

Ni% 4.1 3.01 7.7 0.9 10.3 14.9 0.1 0.1 0.3

Fe% 17.1 33.9 35.9 19.2 - 27.9 32.7 16.6 28.7

S% 16.3 24.5 34.1 - 25.3 28.8 0.8 0.5


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Applications to Other

Cu/Ni/PGM Concentrates

% Recovery

Concentrate TypeElements

D F G H I J K L MCu 99.9 99.3 99.0 99.3 99.7 99.6 99.3 85.0 99.2

Ni 99 93.8 99.6 98.7 98.9 98.7 96.7 - 95.5

Au 99 97.1 84.3 96.0 97.9 82.9 91.5 96.4 53.6

Pt 95 97.4 98.2 99.0 97.9 93.9 93.9 99.1 95.3Pd 94 98.1 93.9 98.4 96.2 95.6 94.9 96.3 96.3



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Applications to Other Feeds

Cu/Au concentrates

Refractory Au ConcentratesCu/Ni/PGE mattes

Pt Laterites

Automobile catalysts


T f C O d C


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Other Applications

Cu - Au concentrate

(28.9% Cu,5.8 g/t Au) PLATSOLTM recovery

99.7% Cu

95.9% Au

No cyanide!


T t t f C O d C t t


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Other Applications

Refractory Au ores-concentrates(non-preg

robbers)

FeS2 - FeAsS conc

19.9 Au, 19.4 g/t Ag

PLATSOLTM recovery

Au 96%, Ag 99.5%

No cyanide!


T t t f C O d C t t


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SEPON Copper Process

Atmospheric leaching process for whole oreto leach copper oxides/carbonates/secondary sulfides

After CCD wash, pyrite and sulfur are floatedas a concentrate and sent to a hightemperature autoclave for oxidation.

Autoclave is the chemical engine for theSepon plant producing acid, ferric sulfate andheat to sustain the atmospheric leachprocess.


T t t f C O d C t t


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Autoclave and Post-Autoclave Chemistry

Autoclave formation of basic ferric sulfate (22O C)

2FeS2(s) + 7.5O2 + H2O = Fe2(SO4)3 + H2SO4

S + 1.5O2 + H2O = H2SO4

Fe2(SO4)3 + 2H2O = 2Fe(OH)SO4(s) + H2SO4

Post Autoclave Re-Leach of Basic Ferric Sulfate

(100 C)

2Fe(OH)SO4(s) + H2SO4 = Fe2(SO4)3 + 2H2O


T t t f C O d C t t


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SEPONLOCALITY

MAP


T t t f C O d C t t


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SEPON

PROCESS BLOCK

FLOWSHEET

CRUSHING

MILLING

SURGE

NEUTRALISATIONWASH CCD

WASH CCDWASH

WATER

TAILINGSFe Acid

Cu LOSS

CLARIFICATION

SURGE

ATM LEACH

HEX

DIRECT HEX

SX EW

COOLING TWR

RAF CCD

CATHODE

FLOTATION

SURGE

AUTOCLAVE

FILTER

EXCESS

PYRITE

POX LEACH

STEAM

Fe Acid

ADDN

WASH

WATER



Next Step Construct ion


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Treatment of Copper Ores and ConcentratesNext Step Construct ion

Example: Sepon Copper and Gold Operation

Gold Operat ion

Copper Operat ion

Padan Camp

Khanong Copper Orebody




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Sepon Copper Ramp Up

Plant designed for 60 ktpa Cu productionCommissioning commenced Oct 2004

Ore commissioning Feb 2005

First cathode harvested March 2005

2005 Production: 644kt milled, 30.5kt stripped

2006 Production: 1,231kt milled, 60.8kt stripped 2007 Production: 60-63kt

Q1 2009 Second POX circuit on line

Current Developments in the HydrometallurgicalTreatment of Copper Ores and Concentrates


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Conclusions

Hydrometallurgical Treatment of Copper Ores

and Concentrates is Continuing to Develop

New Chemistries and Process OptionsEmerging

Central use of SX-EW for Copper Recovery

Theory and Practice are Working together

Hand-in-Hand

Current Developments in the HydrometallurgicalTreatment of Copper Ores and Concentrates


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Thank You!

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