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The BOLEO CopperThe BOLEO Copper
ProjectProject
September 2002September 2002
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BOLEO Copper Deposit
• Located in Baja California, Mexico
• Ore is complex, fine grained oxide,sulphide and mixed oxide / sulphidecontaining 40% clay
• Treatment is complex
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Project History1997
• Project optioned by International CuratorResources
• Fluor Daniel Wright conducted feasibility
study based on extensive testwork byLakefield, CMRI, Pocock and others
• Complex process with high capital andoperating costs
• Project put on hold
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Ore Preparation
- SAG Mill
Oxidation
Leach
Reduction
Leach
Neutralization
In-Pulp Sulfide
Precipitation
Bulk Sulfide
Flotation
Filtration and
Washing
Concentrate
Roasting
Calcine
Leaching
Copper SX/EW
Zinc SX/EW
Cobalt SX/EW
Boleo Ore Rejects
H2SO4
H2SO4 + SO2 + S
High Acid
Consuming Ore
H2S
Floatation ReagentsFloatation Tails
to Disposal
Wash Water
Filtrate to Leach
Air SO2 to Leach
H2SO4 + Water
Copper Cathode
NaOH
NaOH
Zinc Cathode
Cobalt Cathode
Waste Solution to Disposal
Fluor 97 Base Case
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Project History2001 - 2002
• Project returned by Mintec InternationalCorporation
• Bateman asked to review 1997 study and
develop a simpler, conventional, process• Conducted scoping study for simpler, lessexpensive process, based on previous test
reports• Proposal for full feasibility study with
additional testwork
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Geology and Mineralogy
• Boleo’s Cu-Co-Zn mineralisation occursin mantos with gradation in mineraltype and metal grade from a distinct
(barren conglomerate) footwall overlaindirectly by high grade ore to a less
distinct gradational hanging wall.
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Mineralogy (Continued)• 1955 US Geological Survey study of the
Boleo deposit provides an overview of thecomplex and highly variable mineralogy of
the manto structures. Notable featuresinclude;
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Mineralogy (Continued)
High clay content (up to 60%);Saline in-situ water content of 20-25%;
Large variety of oxide mineralization,including simple oxides, carbonates,oxychlorides, silicates and mixed
(ferrite) oxides;Sulfides, when present, of extremely finegrain size.
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Process Implications
• Solid – Liquid Separations will beChallenging due to Clayey Oretypes
• Process in Seawater (high chloride) dueto Salinity of Natural Ore
• Must Use a Variety of Chemistries to
Dissolve all Metal (Cu/Co/Zn) Minerals
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Design Objectives
• Keep it Simple• Inexpensive
• Use proven process steps• Maximum use of previous testwork data
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Design Basis
11,500 t/d
47,000 t/aCopper production
2,750 t/aCobalt production
20,000 t/aZinc production
5.54 %MnO2
0.62 %Zn (oxide and sulfide)0.089 %Co (oxide and sulfide)
1.36 %Cu (oxide and sulfide)
Average ore grade
4,025,000 t/a Annual ore throughput
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Testwork Review
• Extensive testing done on all unitoperations for previous study
• Some results appeared to have been
overlooked (thickening) and have beenrevisited
• Conclusion – Testwork data would form good basis fordevelopment of new process
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Process Options Review
• Seven process options considered andassessed according to
– Technical viability (proven vs. novel)
– Perceived capital and operating costs
– Operability
• One option chosen as base case forscoping study
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Major Process Changes
• Removal of sulphide flotation androasting operations
• Addition of CCD circuit for solid-liquidseparation to allow base metal recoveryfrom SOLUTION, NOT SLURRY
• Based on high rate thickening testresults from previous work
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Thickening Testwork Review• Tests done by Pocock Industrial Inc on leach residues
• Initial tests indicated settling rates of up to 2 m2 /t/day.These high figures preclude efficient use of CCD circuit –hence flotation-roasting option considered previously.
• Two high-rate thickening tests at end of test campaignshowed settling rates of 0.1 m2 /t/day. These resultsappear to have been overlooked in previous study.
• Results reviewed by Bateman and Delkor
• Decision taken to proceed on basis that high-ratethickening test results are indicative of full-scaleoperation.
• Follows Bateman experience on similar clayey ores (eg.Bulong)
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Process - Basic
MILLOXIDISING
LEACH
REDUCING
LEACHCCD
Cu
SX / EW
SULPHIDE
PRECIP
SULPHIDE
LEACH
Zn
SX / EW
Co
SX / EW
Acid SO2 Water
Tailings
Copper
CobaltZinc
Oxygen
H2S
Tailings
Leach
Residue
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Process - Detail
OX
LEACH
RED
LEACH
NEUT 1
CCD
NEUT 2
TAILINGS
Cu SX
Cu EW
NEUT 3SULPHIDE
PRECIP
SULPHIDE
LEACH
Fe
REMOVAL
Cu / Cd
CEMENT
Zn SX 1Zn EW Zn SX 2
NEUT
Co SXCu / Zn
IX
Co EW
Ore
Acid
SO2
HAC
Zinc
Cathode
HACLime
Air
Decant Tailings
Copper
Cathode
HAC H2S O2
Air
Limestone
Zn Dust
Cobalt
Cathode
NaOH
NaOH
Limestone
Air
Water
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ProcessCrushing & Milling
• Primary jaw crusher
• Scrubber for clay removal
• Single stage ball mill for scrubber
oversize
• Cyclone classification
• 40% w/w solids @ P80 = 200 µm
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ProcessLeaching
• Two stage leach maximises recoveries
• Oxidising leach – Majority of copper and some zinc leached
– High acid consumption due to gangue• Reducing leach
– Metal values associated with manganesedioxide (mainly cobalt) leached
– Reducing conditions maintained with SO2
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Leach Chemistry
• Oxidizing Leach Using Natural MnO2 in ore
MS + MnO2 + 2H2SO4 = MSO4 + MnSO4 + 2H2O + S
where M = Cu, Co, Zn
• Reducing Leach Using Sulfur Dioxide Addition
MnO2 + SO2 = MnSO4
cobalt in Mn-Oxide is leached
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Ore Characterization Tests(From Fluor Study)
Bed
Number
No. of
Intervals
Sulfide
(%)Carbonate
(%)
Net MnO2
(%)
2 27 0.09 7.06 9.8
3AA 9 0.28 2.15 8.1
3A 78 0.82 4.49 7.9
3 147 0.24 3.40 5.9
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ProcessLeaching
• Overall Leach recoveries
– Copper 91%
– Cobalt 87%
– Zinc 73% – Manganese 97%
• Acid consumption ~180 kg/t ore• SO2 consumption ~ 25 kg/t ore
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ProcessStage 1 Neutralisation
• Partial neutralisation with high acidconsuming ore (HAC)
• Product solution is amenable to Cu
SX/EW• Two functions:
– Raise pH after leaching – Oxidise Cu1+ to Cu2+ (air sparging)
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Neutralization Chemistry
• High Acid Consuming Ore is Available atSite and Contains Ca/Mg Carbonates
H2SO4 + CaCO3 → CaSO4 + H2O + CO2
H2
SO4
+ MgCO3
→ MgSO4
+ H2
O + CO2
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ProcessCCD
• Six large thickeners
• Washing with discharge solution fromsulphide precipitation (free of copper,
cobalt and zinc), plus sea water make-up
• 97% washing efficiency
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ProcessStage 2 Neutralisation
• Tailings neutralisation with HAC andlime
• Neutralisation to pH 5 to 6 for soluble
metal precipitation• Manganese not precipitated – contained
in soluble form in tailings dam
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ProcessCopper SX from Partially Neutralized Leach Solution
• Extraction with LIX984N @ 15% v/v
• Extraction – 2 mixer settlers
– 98% extraction
• Scrubbing – 1 mixer settler
– Removal of entrained manganese and chloride
• Stripping – 2 mixer settlers
– Stripping with EW spent electrolyte
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ProcessCopper EW
• Electrowinning under standardconditions
• LME Grade A copper produced
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ProcessStage 3 Neutralization
• Neutralization with HAC
• Two functions:
– Neutralize acid generated in copper SX
– Precipitate residual iron prior to sulphideprecipitation
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ProcessSulphide Precipitation
• Acts as primary purification step for zincand cobalt
• Zinc, cobalt and residual copper
precipitated with H2S gas• Iron, manganese, magnesium,
aluminium and calcium remain insolution (recycled to CCD in wash)
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ProcessSulphide Leach
• Precipitated sulphides dissolved at high
efficiency in oxidising pressure leach @150°C
• Sulphur oxidation controlled to producesome elemental sulphur (assists withoverall sulphur balance)
• Acid provided in recycle from primaryzinc SX
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ProcessSolution Purification
• Zinc / cobalt solution purified in two stages
• Stage 1
– Iron removal by precipitation using limestone andair
– Some copper removed
• Stage 2
– Cadmium removal with zinc dust – Residual copper removed
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ProcessZinc SX
• Extraction with D2EHPA @ 40% v/v
• 2 stage extraction with intermediateneutralisation
• Primary extraction – 1 Bateman Pulsed Column
– No pH control
– 60% extraction
– Raffinate split• 75% to sulphide leach
• 25% to neutralisation
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ProcessZinc SX
• Intermediate neutralisation
– pH raised using limestone – Residue recycled to oxidising leach
• Secondary extraction – 1 Bateman Pulsed Column
– pH control using sodium hydroxide
– 99.5% extraction
– Loaded organic to primary extraction
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ProcessZinc SX
• Scrubbing
– 3 mixer settlers – Physical removal of entrained impurities as well as
chemical scrubbing of calcium
• Stripping – 1 Bateman Pulsed Column
– Stripping with EW spent elecrolyte
• Regeneration – 1 mixer settler
– Iron removal from bleed using 6M HCl
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ProcessZinc EW
• Electrowinning under standardconditions
• SHG zinc produced
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ProcessCobalt SX
• Extraction with Cyanex 272® @ 25% v/v
• Extraction – 1 Bateman Pulsed Column
– pH control using sodium hydroxide
– 99.95% extraction
• Scrubbing – 2 mixer settlers
– Primarily for nickel removal
• Stripping
– 1 Bateman Pulsed Column – Strip solution dependant on cobalt product
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ProcessCobalt Purification - IX
• Residual copper, zinc and others
removed from cobalt electrolyte by ionexchange
• IX columns in “lead-lag” configurationfor maximum efficiency
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ProcessCobalt EW
• Electrowinning under standard
conditions in undivided cells
• Alternative for cobalt sulphideproduction also considered
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ProcessReagents
• Elemental sulphur imported for production of
– H2SO4 (produced in acid plant)
– SO2 (produced in acid plant sulphur burner)
– H2
S (produced from molten sulpur andhydrogen from Naphta reformer)
– Acid plant generates 31 MW net power
• Limestone milled on site• All other reagents used as supplied
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Major Reagent Consumptions
386,000
1,948,000
2,038,000
882,000
1,224,000
7,000,000
Cost
US$
Consumption
t/a
SX Organic Reagents
7,800Sodium Hydroxide
760Flocculant
14,000Hydrogen Sulphide
87,400Sulphur Dioxide*
764,400Sulphuric Acid*
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Metsim ModellingGeneral
• Metsim model set up to calculate
– Flows and compositions of major streams,including recycles
– Major reagent consumptions
– Heating and cooling requirements• Steady-state simulation using simple unit
operations used to simulate more complex
real-life operations• Testwork data and information from previous
studies used where possible
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Metsim ModellingMass Balance Calculations
• High level of accuracy
• 73 components considered in 4 phases – 42 inorganic solid
– 16 inorganic aqueous
– 8 organic aqueous – 7 gaseous
• Major elements include Cu, Co, Zn, Ni, Fe,Mn, Mg, Na, S, Ca, Si, Cl
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Metsim ModellingEnergy Balance Calculations
• Lower level of accuracy
• All stream temperature calculations done byMetsim using thermo data from Metsimdatabase and other sources
• Heat loss from equipment not simulated
• Heat exchangers simulated using steam or
cooling water – no solution interchangesimulated due to model stability
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Metsim ModellingFeed Mineralogy
• Not readily available from previous work
• Mineralogy developed based on
– Previous test results
– Recent sample analyses• Oxide / sulphide split difficult to determine
with any accuracy
• Mineralogy adjusted to produce acid and SO2
consumptions consistent with test results
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Metsim ModellingFeed Mineralogy
SiO2MgSO4
MgCO3CaCO3
MnO2
FeOOH
0.02NiO
Balance0.56ZnO0.350.33ZnS
5.770.08CoO4.000.026CoS
5.541.28CuO
9.230.41Cu2S
%%
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Metsim ModellingResults
• Model results compare well with available test
data and general plant operating data• Excellent tracking of impurities and water
balance issues
• Energy balance results suitable for sizing of heat exchangers
• Metsim model an invaluable tool for accurateplant design
• Model can be easily and quickly adapted formore detailed design during feasibility study
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Capital CostsDirect Field Costs (US$)
202,439,000TOTAL DIRECT FIELD COSTS
7,269,000Transport
8,296,000Infrastructure
5,862,000Instrumentation
14,639,000Electrical
17,885,000Pipework
13,430,000Structures
18,748,000Concrete
6,134,000Site Development / Earthworks
53,681,000Mechanical Equipment
56,495,000 Vendor Supply and Install Packages
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Operating Costs
28,964,551
7,086,347
17,715,687
2,558,652
4,559,194
US$/a
7.96TOTAL OPERATING COST
1.76Power
4.40Consumables
0.64Maintenance
1.14Labour
US$/t
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Summary and Conclusions
• Boleo ores can be settled in High RateThickeners
• Conventional CCD will work
• Cu, Co and Zn recovered from solutionas high quality, saleable products
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Example Projects - Bateman
Mt Gordon
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Insert picture of Mt Gordon Expansion Project
Mt Gordon
Gunpowder Autoclave
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Gunpowder Autoclave
Bulong Nickel Plant
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Ore Preparation
Pressure LeachCCD
SX
Electrowinning
Bulong Nickel Plant
Kasese Cobalt
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Kasese Cobalt
Olympic Dam Expansion
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Olympic Dam Expansion