Novel Chemistry for Precious and Base Metals Flotation

IntroductionCytec has developed a novel family of collectors designed for the flotation recovery of precious and base metals from primary and secondary ores. This family of collectors is based on the novel chemistry, MAXGOLDTM, which is a functionalized dithiocarbamate. This new chemistry is offered under the name AERO® MAXGOLDTM 900 promoter and mineral-specific formulations, the AERO MX-900 promoter series, developed using the FLOTATION MATRIX 100TM approach for flotation recovery of:

• Goldvaluesfromprimarygoldores(freegold,auriferouspyrite, auriferous arsenopyrite and other gold-bearing sulfides)

• Goldandcoppervaluesfromcopper/goldores.

• Nickelvaluesfrommassivesulfidesandultramificores

• PGMvaluesfromavarietyofores

MAXGOLD chemistry is a sustainable alternative to the traditionally used sulfide collectors such as xanthates. Some benefits of the MAXGOLD product line are:

• Theyareliquids,whichaffordgreaterflexibilityindosing.

• Theycanbedoseddirectlyintothemill,conditionersorstage-addedtotheflotationbank.Theydonotrequirereagentdosingsystemstraditionallyrequiredforxanthates.Improved reagent handling also provides significantly less chemical exposure to product.

• Theyprovideequivalentorsuperiormetallurgicalperformance at lower dosages than the traditional collectors.

• Theirreduceddosagealsotranslatesdirectlytoreducedresidual reagent concentrations in the concentrate and tailings. This, in turn, provides significantly better environmental profile over traditional collectors.

In addition to the above listed benefits, MAXGOLD chemistry has been shown to offer the following improved performance characteristics in the flotation plants:

• Demonstratedrobustnessinplantoperation-reducedvariability in plant recoveries, and improved overall gold recovery of 2-4% or greater.

• Agreenerprofilethanstandardproducts,especiallyxanthates.

• Veryeffectiveintheflotationofpyriteandarsenopyriteinmildly acidic and neutral circuits.

• CanoperateinabroadpHrange,thusitcanbeusedforcopper/goldoreswithselectivityagainstpyriteinmildlyalkalineandalkalinepulps.

• Providesgreaterflexibilityintermsofadditionpoint(mill,sumps, conditioners, regrind, etc).

• Canalsobealsousedasasecondarycollectoratlowdosages(5g/t-15g/t),inconjunctionwithothercollectorsin the rougher or cleaner circuits.

• Fasterkineticsintheflotationofsulfidesandpreciousmetals than traditional collectors; this is an important advantage in circuits with shorter residence time.

• Improvedrecoveryofmiddlingsorcompositeparticles.

• Effectivenessatsignificantlylowerdoseratesascomparedto traditionally used collectors such as xanthates.

• Greaterflexibilityinuseasapartialreplacementforxanthates.

• Excellentcollectorforbulksulfideflotationandpreciousmetal values including free gold, electrum, and tellurides.

• ExcellentcollectorforCu,AuandMovaluesfromCu-Mo-Auoresrequiringnosecondarycollectors.

• Canbeusedatlowdosages(5g/t-10g/t)inflashfloatcellsimproving recovery of precious metals and gold-bearing iron sulfides.

Case Study

OverviewA plant trial was conducted in a large epithermal gold operation located in North America that was facing significant losses of gold in fine particles. Based on the FLOTATION MATRIX 100 approach for reagent selection and optimization andusingAEROMAXGOLD900(AEROMX-900)promoter as part of the chemical system, improvements to the performance and significant benefits to the process were obtainedwhencomparedtothestandardreagentPotassiumAmylXanthate(PAX).

Process Parameters and FlowsheetThe circuit was composed of SAG and ball mill in closed circuitwithap80setpointof150µm.Theorepassedthrougha gravity concentration circuit which the tails fed the flotation. The collector was added to a conditioning sump prior to the flotationcircuitandtheflotationwasperformedatnaturalpH(7.5–8.5)using125m3tankcells.Theflotationconcentratereported to a cyanide leach.

Thetrialwasconductedusingacombinationof40g/tofAEROMX6205and10g/tofAEROMX-900promoters,asafullreplacementfor50g/tofPAXintheflotationcircuitforfiveweeks.

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Data Analysis and Trial ResultsIn order to understand the variability in the flotation circuit, four months of historical data were analyzed, see Figure 1. ThisbaselinedatarepresentsgoldinthefinaltailswhenPAXwas used as the collector. The average Au in the tails for this periodwas0.25g/taspresentedinFigure1.Thiswillbeusedas a baseline for comparison with the trial data.

The Au content in the tails during the trial period is presented in Figure 2, it can be observed that the average Au in the tails duringthetrialperioddroppedto0.19g/t.

Whencombiningthehistoricaldata(Figure1)withthetrialperiod(Figure2),thetrendinthegoldtailsisreadilyevident:

• SignificantdropintheAuvaluesintheflotationtails:fromanaverageof0.25g/tusingPAXto0.19g/t.

• Morerobustperformancewiththenewcollectorsystemwith reduced swings in tails value.

This improvement is estimated to generate an additional one million dollars of revenue to this operation, representing a returnontheinvestment(ROI)ofabout480%.Anadditionalbenefit observed was that more gold reported to the gravity circuitthanwhenPAXwasused.ThiscanbeattributedtotheactivationofauriferouspyriteinthegravitycircuitbyPAX,which leads to gold reporting to flotation instead of being recovered in the gravity circuit.

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FIGURE 1 - Historical Data - Au in Final Tails

FIGURE 2 - Trial Data - Au in the Final Tails

ShippingAERO MAXGOLD 900 and the series AERO MX-900 promotersareshippedindrums,totesorbulkcontainers.Forinformationonbulkdelivery,contactyourCytecsalesrepresentative.

Storage and HandlingAERO MAXGOLD 900 and the series AERO MX-900 promotersarecombustibleliquids.Provideadequateventilation. Do not heat with an open flame or place in the presence of an ignition source or contact it with an oxidizing material with which it may react. The material should be stored in a cool, well ventilated area away from any sources of ignition. If product is spilled, remove sources of ignition, cover with an absorbent material, sweep up and place in a properly covered waste disposal container. Flush area with water and dispose of properly.

Health and SafetyBefore handling these materials, read the appropriate Cytec Material Safety Data Sheet for more detailed information on physical properties, safety, health and environmental data.

Causesburnsofeyesandskin.Maycauseallergicskinreaction.

Combustibleliquidandvapor.

Reagent Selection and Optimization – FLOTATION MATRIX 100™FLOTATION MATRIX 100 is a new holistic approach to mineral flotation optimization that combines Cytec 100 yearsofexperienceinflotation,uniquechemicals,andourunmatched expertise and insights to consistently deliver measurable improvements in metallurgical, operational and financial performance.

FLOTATION MATRIX 100 is designed to deliver a range of measurableresultsbytakingintoconsiderationthedynamicinteraction of the ore body and plant characteristics with the chemicals in the flotation process. The benefits that can be experienced by following this approach are:

• Optimizedreagentperformance

• Enhancedrecoveryofallvalueminerals

• Increasedyield

• Improvedconcentrategrades

• Acceleratedimplementationofrecommendationsfollowing needs assessment

• Significantcostsavings

Contact your Cytec sales representative for more information on Cytec products.

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