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8/13/2019 Intec Gold Process
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Intec Ltd
Engineering for Superior and
Sustainable Metals Production
Intec Gold Process
March 2009
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Intec Gold Process Page 2
This brochure was carefully produced. Nevertheless, the authors do not warrant the information
containedtobefreeoferrors.Readersareadvisedtokeepinmindthatstatements,data,illustrations,
procedural
details
or
other
items
may
inadvertently
contain
inaccuracies.
Allrightsreserved(includingtranslationinotherlanguages).Nopartofthisbookmaybereproducedin
any form,nortransmittedortranslated intoamachine languagewithoutwrittenpermission fromthe
publishers.
IntecLtd,2009
PrintedinAustralia
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TableofContents
1 Introduction.......................................................................................................................................... 4
2 IntecGoldProcessFlowsheet............................................................................................................... 6
3 IntecGoldProcessProcess................................................................................................................... 8
3.1 ConcentrateGrindSize................................................................................................................. 8
3.2 LeachReactions............................................................................................................................ 8
3.2.1 Leachreactionsforarsenopyrite.......................................................................................... 8
3.2.2 Leachreactionsforpyrite..................................................................................................... 9
3.2.3 GoldstabilityintheIntecGoldProcessleachcircuit............................................................ 9
3.3 GoldRecovery............................................................................................................................. 10
3.3.1
ActivatedCarbon
.................................................................................................................
10
3.3.2 Resins.................................................................................................................................. 11
3.4 ByProductRecovery................................................................................................................... 11
3.4.1 Silver.................................................................................................................................... 11
3.4.2 Copper................................................................................................................................. 12
3.4.3 Elementalsulphur(seleniumandtellurium)...................................................................... 12
3.4.4 Minormetals(zinc,cadmium,magnesium,manganese,etc)............................................ 12
4 IntecGoldProcessAdvantages........................................................................................................... 13
4.1 EnvironmentalAdvantagesoftheIntecGoldProcess................................................................ 13
4.2 EconomicAdvantagesoftheIntecGoldProcess........................................................................ 13
5 IntecExperience.................................................................................................................................. 16
6 CapabilitiesofIntec............................................................................................................................. 17
7 Conclusion........................................................................................................................................... 17
8 References.......................................................................................................................................... 18
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1 IntroductionThe major proportion of the worlds gold reserves are goldbearing refractory ores, which are
dominatedby ironsulphides suchasarsenopyriteandpyrite.Thereareanumberof factors thatcan
renderagoldbearingorerefractory,asshowninTable1.
Table1.CausesofRefractoryCharacteristics
Type CausesofRefractoryCharacteristics
Locked Physicallockingorsubstitutioninsilicates,sulphides,carbon,etc.
Passivation Passivationduetoformationofachemicallayer.
Chemical Formationofauriferouscompoundse.g.goldtelluridesandaurostibnite.
Adsorption Adsorptionofdissolvedgoldbyactivecarbonaceousmaterialintheorepulp.
Currentconventionaltechnologiesrequireanoxidativepretreatmentstepsuchaspressureoxidationor
biologicaloxidation
to
liberate
gold
from
the
concentrates.
The
oxidised
residue
is
then
leached
using
an
alkalinecyanidesolution,followedbypurificationandgoldrecovery.
Incontrast,theIntecGoldProcess(IntecGoldProcess)usesamixedhalide lixiviant(chloride,bromide
and/oriodide),permittinggolddissolutiontooccurconcurrentlywithsulphidemineraloxidation.Once
the gold is solubilised, it can be extracted from the solution onto activated carbon or ionexchange
resins, either in the leach pulp (carboninpulp/resininpulp), or separately in columns (carbonin
column/resinincolumn).Gold istypicallyelutedusingappropriatecomplexingagents,andtheneither
electrowonasgoldmetalorcementedusingreductants(e.g.zincpowder).
Therefore,the
Intec
Gold
Process
differs
from
all
current
commercial
practices
for
treatment
of
refractorygoldconcentrates,wheregoldisextractedfromtheoxidationresidueusingcyanide.Cyanide
systemsrequireaseparatededicatedleachcircuitandcostlymeasuresforresidualcyanidedestruction.
Importantly,however,theIntecGoldProcesscanberetrofittedtoexistingoperationswhereacyanide
stripisemployedtorecovergoldfromactivatedcarbon,priortoanelectrowinningcircuit(Zadra(Zadra
1951)orAngloprocesses).
The Intec Gold Process has successfully treated concentrates containing the full range of minerals
associatedwithgold(Table2).However,highlycarbonaceousfeedsthatcontainactivecarbonmaybe
unsuitable fordirect treatmentusing the IntecGoldProcessdue toexcessivepregrobbingbehaviour
duringleaching.
In
these
cases,
concentrate
pre
treatment
or
leach
residue
treatment
techniques
are
recommendedtoattainhighgoldrecovery.
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Table2.MineralsSuitableforTreatmentUsingtheIntecGoldProcess
ClassofMineral TypicalMinerals ChemicalFormula
Arsenides Arsenopyrite
Enargite
Tennantite
FeAsS
Cu3AsS4
(Cu,Fe)12As4S13
Sulphides Pyrite
Pyrrhotite
Chalcopyrite
Stibnite
FeS2FeS
CuFeS2Sb2S3
Tellurides Krennerite
Hessite
AuTe2Ag2Te
Elemental Electrum
Nativegoldandsilver
AuxAgyAuandAg
Antimonides Aurostibnite
Tetrahedrite
AuSb2(Cu,Fe)12Sb4S13
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Golddepleted liquor issent to thepurificationcircuitwherebyproductsareprecipitatedwith slaked
lime. The precipitated solids are separated by filtration where they are washed, and the filtrate is
recycledtoleachingoperations.
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3 IntecGoldProcess3.1 ConcentrateGrindSizeDuring conventional flotationand concentrationprocessing,particlesoforeare typicallyground toa
sizerange
of
p80
=70
100
m.In
most
cases
leach
kinetics
are
significantly
enhanced
when
concentratesareregroundtoafinerparticlesize.Wherearsenopyriteisthesolegoldbearingmineral,
asizeofp80=3040mhasprovenadequatetoachievegoodgoldextractionandanacceptableleach
retentiontime.Wheregoldislockedinpyrite,thegrindsizewillprincipallydependonthereactivityof
thepyrite. Forahighlyactivepyrite,thegrindemployedforarsenopyrite isused,butmorerefractory
pyriteexamplescommonly require finergrinding. Thismayextend toanultrafinegrind (
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TheoxidativeactionoftheCu2+/Cu+coupleissupplementedbytheFe3+/Fe2+couple,sincea background
concentrationofironisalwayspresentintheprocessliquor. Thepotentialachievedundertheinfluence
oftheCu2+andFe3+is~850mV(versusSHE)inthepresenceofoxygen.
In thepresenceof ferric ion, thearsenicacid readily forms insoluble ferricarsenateaccording to the
followingreaction:
H3AsO4+Fe3+
FeAsO4(s)+3H+ (5)
Ferricarsenate(scorodite)formed inthehighchlorideelectrolyte,andundertheoperatingconditions
usedintheIntecGoldProcess,istypicallycrystallineandstableinthenaturalenvironment.
3.2.2 LeachreactionsforpyriteTheoxidationofpyrite(FeS2) intheIntecGoldProcess isachievedviathesameseriesof intermediate
reactionsasemployedforarsenopyriteoxidationaccordingtothefollowingoverallreaction:
4FeS2(s)+15O2(g)
+2H2O
8SO42
+4Fe3+
+4H+
(6)
It should be noted that the pyritic sulphur is oxidised all the way to sulphate in contrast to the
arsenopyriticsulphur that isonlyoxidised to theelementalstate.Thushigheramountsofoxygenare
consumedinleachingpyritecomparedtoarsenopyrite.
Pyrite ismorerefractorythanarsenopyrite,typically requiringa finergrindsizetoachieveacceptable
reaction kinetics. However, individualpyrite samplesexhibitvariable reactivity that is thought tobe
influencedbyarsenicsubstitutionforaportionofthesulphurinthecrystallattice. Suchpyriteisoften
termed arsenical pyrite, and the higher the arsenic contamination the more the pyrite reactivity
approaches thatof true arsenopyritewith anAs/S ratioofone. Forparticularly refractory (lowAs)
examplesofpyrite,ahigheroxidationpotential than isachievablewithairmaybeneeded,andpure
oxygencanbeused.
Tomaintainastablebackgroundirontenorintheprocessliquor,ferricisprecipitatedashematitebythe
additionoflimestoneatapHofapproximately11.5accordingtothefollowingreaction:
2Fe3++3H2OFe2O3(s)+6H+ (7)
The sulphate precipitates as calcium sulphate (crystalline anhydrite) due to the presence of calcium
chlorideinthebrinematrix,accordingtothefollowingreaction:
2H+
+SO4
2
+CaCO3(s)
CaSO4(s)
+H2O
+CO2(g)
(8)
3.2.3 GoldstabilityintheIntecGoldProcessleachcircuitLeachinggoldintoanacidicsolutionrequireshighlyoxidisingconditions,otherwisethegoldremainsas
an insolublemetal.Active sulphides (e.g. pyrite) or inorganic carbonaceousmaterialsmake leaching
difficultastheunleachedmattercanreducesolubilisedgoldbacktothemetallicstate.Thetermcoined
for this phenomena is pregrobbing.As a consequence, historically gold operationshave employed
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alkalicyanide treatments for recoveryofgold from leach residues.While thegoldcyanidecomplex is
extremely stableacrossa rangeofconditions,cyanide isahighly toxicsubstanceand itsuse isbeing
restrictedworldwide.
Analternativesystemtocyanideistousehalides.Thestabilityofgoldhalidecomplexesisgivenbelow,
andclearly
the
gold
complexes
become
more
stable
as
the
halide
changes
from
chloride
to
bromide
to
iodide:
Au+2Cl AuCl2
+e E=+1.00(V)vsSHE (9)
Au+4Cl AuCl4
+3e E=+0.92(V)vsSHE (10)
Au+2Br+Br2 AuBr4
+e E=+0.80(V)vsSHE (11)
Au+2I+I2 AuI4
+e E=+0.55(V)vsSHE (12)
Gold recovery processes using only a single halide are difficult, and no commercial processes are
available
(Marsden
and
House
2006).
This
is
due
to
chloride
complexes
being
insufficiently
stable
to
preventpregrobbing,andcircuitsusingjustbromideoriodidestruggletolimitthelossoftheexpensive
halide.Incontrast,Intechasdevelopedandpatentedtheuseofmixedhalidesystemsfortherecovery
ofbaseandpreciousmetalsfromsulphideandoxidefeedstock.Thekeyadvantageofamixedsystemis
thatthemajorhalidecanbechloride,andonlytraceamountsofthegoldstabiliserhalide(bromideor
iodide) need to be used. In this manner, the circuit is economically viable and achieves excellent
recoveryofgold.
3.3 GoldRecoveryExtractionofgoldfromthemixedhalideliquorcanbeachievedusingactivatedcarbonorionexchange
resins.Both
techniques
have
been
successfully
tested
by
Intec
and
third
parties.
3.3.1 ActivatedCarbonActivated carbon is the most widely used adsorbent for the recovery of gold from cyanide leach
solutions. Either the Zadra (Zadra 1951)orAngloprocesses areused, and are known tobe reliable,
simpleandcosteffective. Inthesesystems,goldcyanidecomplexesare loadedontoactivatedcarbon,
andthenstrippedusingacombinationoftemperature,pressureandalkalicyanidesolutions.
ThegoldhalidecomplexesusedintheIntecGoldProcessarealsoreadilyloadedontoactivatedcarbon.
Extensive testingby Intecand theAJParkerCentre forHydrometallurgy,Australia,hasdemonstrated
thefulllifecycleperformanceofactivatedcarbon.Repeatedloadingofgoldhalidesandstrippingtests
usingcyanidesolutionsweresuccessfullycompleted.
Retention time for gold adsorptionwas 1015minutes,which is similar to conventional practice for
cyanidesystems.Gold loadingontothecarbonwastypically25%w/wduetotherelativelyhighgold
concentrations insolutions typically10100mg/l.Thetestingconcludedthatgoldcouldberecovered
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byconventionalelutionorbyburningofthecarbon,withthechoicedependingontheeconomicsofthe
individualsituation.
However,therearetwomajor limitationstocarbonsystems.The first isthatactivatedcarbon isnon
selective forgold,withcoloadingofcopperandtheformationof ironprecipitatesobserved.Astrong
hydrochloricrinse
of
the
carbon
is
sufficient
to
remove
copper
and
iron
prior
to
gold
stripping,
but
this
clearlyadds costandcomplexity to theoperation.The second limitation is thatactivatedcarbon isa
reductantandcanreducesolutionpotentialstotheextentthatelemental/colloidalgoldcanbedirectly
cementedontothecarbon.Thiscan leadtodepositionofgoldalongsurfacesofequipment,reducing
theoverallefficiencyofthesystem.
Nevertheless, direct integration of the Intec Gold Process with existing carbon treatment circuits is
viable.
3.3.2 ResinsIn
recent
years,
ion
exchange
resins
have
been
widely
used
across
all
metal
industries.
However,
industrial use of resins for recovery of gold has predominantly been confined to Eastern European
countries,wheregoldthiosulfatechemistryhasprevailedinsteadofgoldcyanidechemistry.Resinshave
been developed due to the well documented inability of goldthiosulfates to load onto carbon
(Gallagheretal.1990;Navarroetal.2006).
In Intecprocess liquors, resinshavebeenshown tobemoreselective forgold loading thanactivated
carbon.Also,unlikecarbons,resinsdonotneedtoberegeneratedviaathermalprocess,whichmeans
theinitialcapitalandthesubsequentoperatingcostsaresubstantially lowerthantheactivatedcarbon
technology. Loaded resinshavebeen successfully strippedwith thiosulfateand/or thiourea solutions,
whichcan
be
readily
forwarded
directly
to
electrowinning
or
zinc
cementation
circuits.
3.4 By-ProductRecovery3.4.1 SilverSilveriscommonlyassociatedwithgoldconcentrates.However,highcyanideconcentrations(>0.5g/L)
areoftenrequiredtoenablesilversolubilisation,andrecovery isgenerally limitedtozinccementation
circuitsinsteadofactivatedcarboncircuitsduetopoorsilverloadingcharacteristics.
SilverisreadilysolubilisedintheIntecGoldProcessduetothemixedhalidebrine.Ifthesilvercontentin
theconcentrate
is
high
compared
to
the
gold
content,
then
selective
recovery
onto
resins
or
solvent
extraction is preferred. High purity silver chloride is precipitated from the hydrochloric acid strip
solutions,andthenmeltedtoyieldsilvermetal.
On theotherhand, if the silver content is lowor similar to the gold content, simultaneous recovery
throughtoelectrowinningamixedsilver/goldproductisalsoaviableoption.
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Intec Gold Process Page 12
3.4.2 CopperManycopperconcentratescontaingold.Dependingon thesizeof theproject, the IntecGoldProcess
flowsheet can be modified to recovery copper as metal via electrowinning, copper sulphate
pentahydratecrystalsviasolventextractionandcrystallisation,orcopperoxychlorideviaprecipitation.
3.4.3 Elementalsulphur(seleniumandtellurium)The leach residue from the Intec Gold Process contains elemental sulphur. Intec has successfully
recovered the sulphur by differential flotation from the residue, as the other components are iron
oxides (hematite), calcium sulphate,andanyunreactedminerals.Givenappropriatemarkets, sulphur
canbesold,orburntforenergyandsulphuricacidproduction.
Thecrystalstructureofelementalsulphurisaneightmemberring(S8).Seleniumandtelluriumarewell
known to substitute into these rings, and this is the case when the Intec Gold Process treats
concentrates rich ineithermetal.TheSe/Terich sulphurcanbe separated from the leach residueby
flotationand
re
processed
by
third
parties
for
recovery
of
these
important
and
valuable
trace
metals.
3.4.4 Minormetals(zinc,cadmium,magnesium,manganese,etc)Thepresenceof impurities in the feedconcentrate (e.g.zinc,cadmium,manganese,magnesium,etc)
hasnodetrimentaleffectoneither the leachingorarsenicprecipitationoperations. Nevertheless, a
methodforthemanagementofimpuritiesisrequired.
Firstly,limestoneisaddedtothegolddepletedbleedtoprecipitateresidualironandcopperatpH3.5.
Thesolidsareremovedbyfiltrationandrecycledtothe leach. Impuritiesarethenremovedviaslaked
limeadditionatpH9toforminsolublehydroxidesthatarerecoveredbyfiltrationfordisposal,according
tothefollowingreaction:
MCl2+Ca(OH)2(s)M(OH)2(s) +CaCl2 (13)WhereM=Zn,Cd,Mg,Mn,etc.
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4 IntecGoldProcessAdvantages4.1 EnvironmentalAdvantagesoftheIntecGoldProcessTheinherentenvironmentaladvantageoftheIntecGoldProcessaresummarisedassuch:
Nocyanideisusedintheleachingprocess,andwhenusingresinsnocyanideisrequiredforthe
goldrecoverycircuit.
Arsenic is converted into a stable and benign ferric arsenate (FeAsO4 scorodite), enabling
successfultreatmentofconcentratescontaining>10%arsenic.Thiscomparesfavourablywith
roastingtechnologieswhichcreatetoxicarsenictrioxide(As2O3),whichmustbecarefullystored
andeventuallydisposedofatconsiderableexpense.
Noliquideffluents
Nonoxiousgaseousemissions
Low carbonfoot print due to low energy consumption relative to other minerals processing
technologies(POX,
roaster,
etc)
Underappropriateprojectconditions,azerowasteprocesscanbeimplemented
High overall metal extraction from feedstock (typically > 98%), resulting in stable iron oxide
(hematite)/elemental sulphur/calcium sulphate leach residues with little trace/toxic metals
present.
4.2 EconomicAdvantagesoftheIntecGoldProcessInadditiontohavingsignificantenvironmentalbenefitswhencomparedtoalternativetechnologies,the
IntecGoldProcessalsohassuperioreconomics.Acomparisonofthe IntecGoldProcesstoarangeof
existingprocess
technologies
with
respect
to
plant
capital
and
operating
costs
is
provided.
The
data
is
based upon comparative cost analysis commissioned by Intec in 2004 and compiled by J.R. Goode
(Goode 2005) and HG Engineering (HG Engineering 2005). Further costing data is referenced from
MarsdenandHouse2005(MarsdenandHouse2006).
Thefollowingassumptionswereusedforthecomparison;
PlantlocatedinNorthAmerica
Costsexcludetailingsdisposal,effluenttreatmentandoreminingcosts
Costsincludeflotationandgrindingcircuitswherenecessary
Goldconcentratethroughputofapproximately50,000tpa(at60g/tgold)
Intec
Gold
Process
oxidation
circuit
assumes
the
use
of
air
as
asource
of
oxygen
Costshavebeen inflated to2009 levelsusingaMarshall&Swift/Mine&Millcostescalation
index
Thecomparisonsareonlyindicative,asvariationsinoremineralogyandspecificprojectconditionsand
requirementsmayrendersomeprocessesunsuitable.Sixteenprocessoptionswereincludedinthecost
comparisonassummarisedinTable3;
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Table3GoldProcessingOptions
LeachProcess ProcessOption PretreatmentStep Recovery
DumpLeach 1 None CarboninColumn,Electrowinning
ROM
Ore2 CoarseCrushing CarboninColumn,Electrowinning
3 MediumCrushing CarboninColumn,Electrowinning
4 MediumCrushingCarbon
in
Column,
ZnPrecipitation
5Fine
Crushing,AgglomerationCarboninColumn,Electrowinning
FreeAucon 6* Grinding,Flotation CarboninPulp
Gr
oundOre
7 Grinding,Biooxidation CarboninPulp,Electrowinning
8 Grinding,Roasting CarboninPulp,Electrowinning
9 Grinding CarboninPulp,Electrowinning
10+ Grinding,Flotation CarboninPulp+
11
Grinding,Pressure
Oxidation
Carbon
in
Pulp,
Electrowinning
12 GrindingCountercurrentdecantation
ZnPrecipitation
LockedGold
Concentrate
13Grinding,Flotation,
RoastingCarboninPulp,Electrowinning
14Grinding,Flotation,
BioOxidationCarboninPulp,Electrowinning
15Grinding,Flotation,
PressureOxidationCarboninPulp,Electrowinning
16 Grinding,Flotation ResinColumns,Electrowinning
*Freegoldconcentratesonly+Saleofconcentrate
Figure2highlightstheadvantageoftheIntecGoldProcessintermsofcapitalcostswhencomparedto
the15otherprocesstechnologies.Whilethe IntecGoldProcesscapitalcost issignificantly lowerthan
processoptions515,italsocomparesfavourablytoheapanddumpleachoperationsfortreatmentof
ore.Somefeedstocksareunsuitableforheapordump leaching,andtheseareparticularlysuitablefor
treatmentusingtheIntecGoldProcess.
Figure3highlights theadvantageof the IntecGoldProcess in termsofoperatingcosts.Asexpected,
apart from thecheaperheapordump leachoperations, the IntecGoldProcessoperating cost is the
lowestofallotheravailabletechnologies.
As shown through this indicative cost comparison, the Intec Gold Process has a significant cost
advantageinbothcapitalandoperatingcosttoallotherstandardgoldprocessingtechnologies.
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Figure2ComparisonofPlantCapitalCosts(USDmillions)
Figure3ComparisonofPlantOperatingCosts(USDpertonneROMore)
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5 IntecExperienceOverthe last10years Intechassuccessfullycarriedouttestwork forexternalclientstoevaluateand
prove the IntecGoldProcess technical feasibility,economicandenvironmentaladvantages.Testwork
hasrangedfromproofofconceptstudiestopilotplantcampaigns.Ithasalsoverifiedtheprocessata
demonstrationplant
scale
in
Burnie,
Tasmania.
Examples
of
testwork
are
provided
in
Table
4:
Table4.ExamplesofsuccessfulapplicationofIntecGoldProcesstorefractorygoldconcentrates
ProjectTitle OreTypeAuhead
grade(g/t)Extraction
Recoveryfrom
solution
OtherMetalsin
Concentrate
LaboratoryBenchScaleTests:
Furteigoldproject,
Sardinia
Enargite,Cu3AsS4Pyrite,FeS2
38.7 85%
>98%using
resinsfrom0.3
ppmsolution
10% As,28%Cu,
190g/tAg,1860g/t
Te,750g/tHg
SamplefromPolyus,
Russia
Arsenopyrite,FeAsS
Pyrrhotite,FeS
Antimonite,
Chalcopyrite,CuFeS2
Pyrite,FeS2
91.8 90%>95%
using
carbonfrom10
ppmsolution
6%As,4%Sb,3%C
SamplefromBarrick,
SouthAmerica
Enargite,Cu3AsS4Arsenopyrite,FeAsS
Pyrite,FeS2
48.1 87%
>98%using
resinfrom
2ppmsolution
4.4%As,11.2%Cu,
1.4%C,175g/tTe,
705g/tAg
Samplefrom
GoldCorp
Arsenopyrite,FeAsS
Pyrite,FeS2170 95% notcompleted
15%As,9.8%Si,
1.5%C
PilotplantScaleTest:(closedloopcontinuousoperation)
SamplefromBarrick,
Australia
Arsenopyrite,FeAsS
Pyrite,FeS258.6 >95%
>98%using
carbonfrom10
ppmsolution
0.5%As
In 2004, Intec successfully operated a pilot plant using the Intec Gold Process to treat 30kg/day of
refractory gold concentrateprovidedbyBarrick,Australia.Gold leach extractionobtainedwasup to
96.5%usingasingleleachcircuitandmildgrinding(70m).Goldrecoveryontocarbonwasveryhigh,as
wasplantavailabilityat99%. IntecGoldProcessgoldrecoverywashigherthanthatobtainedbyusing
ultrafinegrinding(10m)followedbycyanideleaching(9092%)inaconventionalcircuit.Thefullscale
ultrafinegrindingoptionwaschosenbyBarrick inearly2001asthemostcosteffectivealternativeto
roastingwhen
compared
to
an
acid
plant,
pressure
oxidation,
and
bacterial
oxidation.
However,
this
optionstill involvesveryhighcostsassociatedwithenergyconsumption levelstoachievetherequired
particlesize,upto 120kWh/tofconcentrateforagrindsizeof10m(EllisandGao2002). IntecGold
Process performance for this sample concentrate suggests that the Intec Gold Process is a more
economic andenvironmentaloption thanultrafine grinding in conjunctionwith cyanide leaching for
thisparticularcase.
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6 CapabilitiesofIntecTheprocessanddesignengineering teamat Intec isable toprovideprocess flowsheetdevelopment,
flowsheet modelling, inhouse process evaluation testwork (laboratory, piloting and demonstration
scale), scoping/feasibility studies, and financial modelling for hydrometallurgical minerals processing
projects.In
many
cases,
acombination
of
common
base
and
precious
metal
hydrometallurgical
circuits
canbeintegratedwithproprietaryIntectechnologycircuits,e.g.theproductionofzincsulphatecrystals
would involve an Intec halide leach, solvent extraction, and then crystallisation from sulphuric acid
brine.
TheIntecteamhasgatheredsignificantexperienceintestinganddevelopingover50projectsinthepast
10 years, for extraction and recovery of gold, copper, silver, lead, zinc, nickel, cobalt, indium, and
platinum. Thetestinghas focusedonagitated leachingcircuits,purificationtechniques (cementation,
solvent extraction, ion exchange resins, and precipitation), and product recovery (electrowinning,
sulphidisation, and precipitation). Two continuous closedloop demonstration plants have been
designed,built,
and
operated,
with
the
$10M
(AUD)
Burnie
Research
Facility
available
for
testwork
and
projectdemonstrationinTasmania,Australia.
TheIntectechnologyisnowcommerciallyavailable.Intecpursuesaflexibleclientperclientapproachto
licensing, royalties, equity participation, orother forms of investment. Exclusive access rights to the
technologyareavailableonageographicalbasis.
7 ConclusionThe IntecGold Process represents anew approach to the recoveryof gold from refractory sulphide
deposits.Theprocesshasbeenproventodeliverhighgoldextractionsandrecoveries,whichcompare
favourablyagainstothertechnologies.Thecapitalcostsandoperatingcostsarerelatively low,making
theIntecGoldProcessattractivetonewoperations.Expansionprojectsshouldalsoconsideremploying
theIntecGoldProcess,asitcaneasilybecombinedwithexistingcarbonorresingoldrecoverycircuits.
Theenvironmentalbenefitsof theprocessareunparalleled,with theeliminationofcyanide from the
leachcircuitandconversionofarsenic intostableferricarsenatebeingcriticalpointsofdifferentiation
withallothertechnologiesforgoldprocessing.
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8 References
Ellis, S. and Gao, M. (2002). "The Development of Ultra Fine Grinding at KCGM". Conference
Proceedings:SME
Annual
Meeting
Phoenix,
Arizona.,
vol,
p,
Ed.
Gallagher, N. P., et al. (1990). "Affinity of activated carbon towards some gold(I) complexes."
Hydrometallurgy25(3):305316.
Goode,J.R.(2005).CapitalCostIntecGoldProcess,Pox,Box.
HG Engineering (2005). Barrick Gold Corporation: Review of Cost Estimate of Intec Refractory Gold
Process.
Marsden,J.O.andHouse,C. I.(2006).TheChemistryofGoldExtraction.Colorado,SocietyforMining,
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Intec LtdEngineering for Superior and
Sustainable Metals Production
orpora e ea quar ers
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