This document examines the sustainability of froth flotation by analyzing the consumption of power, chemicals, and water by the three largest copper producers in 2015: Glencore, Codelco, and Freeport-McMoRan. It finds that while power consumption is relatively low compared to other mining processes, chemical consumption may be unsustainable as the additives used are non-renewable resources. Water consumption is a small percentage globally but raises ethical issues given the arid locations of operations. The document also discusses an alternative "frothless flotation" process being researched and concludes that improvements are needed to increase sustainability, particularly regarding water usage.
1. Froth Flotation Sustainability
Prepared by:
Devin Jackson Rowe
Faculty Advisor:
Dr. Jon Kellar
Professor/Douglas Fuerstenau Professor, Department of Materials and Metallurgical
Engineering
South Dakota School of Mines and Technology
501 E Saint Joseph Street
Rapid City, SD 57701
2. Table of Contents
ABSTRACT 1
1. INTRODUCTION 2
2. SUSTAINABILITY ISSUES 2
2.1. Energy 2
2.2. Consumables 3
2.3. Water 5
3. ALTERNATIVE 5
4. CONCLUSION 6
REFERENCES 7
3. 1
Abstract
In thisreportthe sustainabilityof frothflotationisquestionedbyexaminingthe consumptionof power,
chemical additivesandwaterbythe three largestcopperproducingcompaniesof 2015, Glencore,
CodelcoandFreeport-McMoRan. The amountof consumablesbythese three companieswere thenput
intoperspective by comparingthemtootheraspectof the industry, global consumptionof that
consumable orputunderethical consideration. Throughanalysisof variouslegal reportsandemails
withsite managersthe amountof powerconsumedbyforthflotationisnegligible comparedtoother
aspectsof the miningindustry. Harddata on how much and whatkindof chemical additiveswere
consumed couldnotbe foundfor everycompany,butthe assumptionsmade wouldsuggestthat
sustainabilityislimitedasadditivesmayinclude non-renewableresources. Bya global standard, water
consumptionisactuallyprettylowforthisprocesswhenotheraspectsof civilizationare considered,but
ethical considerationssuggestthatthe waterconsumptionneedstobe reduced. Withthese
sustainabilityissues,improvements tothisprocessneedtobe made or alternative developed.
4. 2
1. Introduction
Froth flotationisone methodof concentratinglow-grade,fine-particleores(210-37 microns). This
processisperformedbyusingwaterasa mediumandmanipulatingthe ore particle’ssurface intobeing
eitherhydrophobicorhydrophilic,thenbubbling airthroughthe watertoseparate the hydrophobic
particles fromthe hydrophilicones. Thismethodof beneficiationconsumessignificantamountswater
regardlessof howmuchof itis reusedbythe operationandsince these processestendtotake place in
arid areas,one can begintoquestionthe sustainabilityof sucha process. HoweverinthisreportIwill
attemptto addressnotonlythe waterconsumption,butthe energyandchemical consumptionbased
on the three largestcopperproducer of May 2015, Codelco,Freeport-McMoRanandGlencore. Copper
producerswere chosen,asthe processof concentratingcopperore iswell knowntonormallyinvolve
flotation, butitshouldbe understoodthatmanyothermineral andore typesare concentrated byfroth
flotation. Iwill alsotalkabouta possible alternative tothe methodandmyresearchintodevelopingit.
2. Sustainability issues
All beneficiationmethodshave theirowndraw backs thatcan limittheirsustainability.Some methods
consume a lotof power,othershave highwearingontheircomponentssopartsneedtobe changed
regularly.Forfrothflotationwaterisakeyissue butthe processalsoconsumesenergyandchemical
additivesare neededtomake the entire processwork. So,Iwill be exploringthese threeissuesin
sustainability.
All the data showninthe below sectionswere basedongovernmentrequiredenvironmental and
financial reportsfromthe respective companies. Also, assome of these companiesproduce more than
justmetal/mineral wherefrothflotationisinvolved,the totalsexpressedinthisreportare basedon a
percentage of the total numberreportedbythe company.Thiswasdone by takingthe numberof
operationsthatuse frothflotationanddividingbythe total numberof operationsownedby the
company. For example, tax informationsuggests 12 of the 14 operationsof Freeportare relevantso
85.7% of the company’stotal isreportedinthispaper, likewise21of 128 operationcontrolledby
Glencore wouldlikely have frothflotationsoonlyabout16.4% of theirtotal wasconsidered. For
Codelcothe informationwaslistedbyoperationsiteandsoonlythe siteswhere flotationisusedwere
considered,meaningnoadjustmentwasnecessary.
2.1.Energy
As faras energyconsumptionisconcerned,accordingtoastudyby the U.S. Departmentof Energyall
separationprocessinthe miningindustryaccountforabout4% of the total energyconsumedbythe
industry. Itis true that flotationconsumesthe mostenergyof all the separationmethods but itstill
onlyaccountsfor a little lessthanaquarter of that 4%. Howeverthe studywasn’tspecifictoany
particularoperation,justalowestpracticedaverage wasreported. Thisstill managestoputits
sustainabilityincontext,if we reallywanttosave energyperhapswe shouldfocusonthe grinding of
oresas thisaccounts for 40% of energyconsumedbythe miningindustry. Evenventilationconsumes
more energythatall of the separationscombined,accountingforabout10%. Still thisreportisn’t
exactlyaboutputtingflotationenergyconsumptionintoperspectiveagainstall otheraspectsof the
miningindustry,butmore aboutshowingabouthow muchenergythisprocessmayconsume globallyby
focusingonthe top three copperproducersinthe world.
5. 3
As mentionedthe studybythe U.S.Departmentof Energydidn’tgive detailsaboutaspecificoperation,
fortunately Ididmanage toobtaininformationfromasite leaderof a Codelcooperationthatsuggesta
site that producesconcentrateswill spendabout7% of theirenergyonflotation. If we make the
assumptionthatthis isa typical percentage thenwe canapplyitto the numbersreportedtothe
governmentbyCodelco,Freeport-McMoRanandGlencore intheirannual sustainabilityreports.
However,the reportsbreakdownenergyuse intofuel andelectrical andsince myinformantdidn’t
specify whatamountof eachwas usedI’ll applythe 7% across both.This informationissummarizedin
Table 1 below.
Table 1. Energy Consumption Reported from 2012 to 2015. Boxes withdashes meannodata couldbe foundfor that year.
Electrical 2012 (GWh) 2013 (GWh) 2014 (GWh) 2015 (GWh)
Codelco 387.90 377.01 397.16 -
Freeport-McMoRan - - 526.53 515.43
Glencore 311.23 349.74 346.53 -
Fuel
Codelco 297.67 309.38 308.82 -
Freeport-McMoRan - - 1098.12 984.48
Glencore 368.99 436.37 455.62 -
Total
Codelco 685.57 686.39 705.98 -
Freeport-McMoRan - - 1624.64 1499.91
Glencore 680.22 786.10 802.15 -
If we consider2014’s estimatedtotal energyconsumptionbyflotation,3100 GWh, andcompare itto
the energyconsumptionof the worldlargestcity,Tokyo,of the same yearwhichwasapproximately
5300 TWh (or 5300000GWh) itwouldappearthat the flotationsconsumptionisrelativelylow bya
global standpoint.
2.2.Consumables
No specificdataexistsforhowmuchchemical additivesthese companiesuse annually. It’sevendifficult
to findoutwhat kindof frothers,collectorsandpHadjustingchemicalsthesecompaniesuse,asall of
thisinformationare usually consideredtrade secretsandtheyare notlegallyrequiredtodisclose thisto
the public,unlike withwaterandpowerconsumption. Table 2below summarizesmycontactattempts,
where responseswere made tomyinquiryabouthow muchadditiveswere usedbyanyparticularsite
overa givenyearand howmuch powerthe flotationprocessedconsumedatthatsite. All contact
attemptswere byemail,phone callswere notmade asnumberswere unavailable,siteswereinan
inconvenienttime zoneorlanguage barrierswere present.
Table 2. Summary of Contact Attempts.
Company Site or Job Title Response
Glencore
ErnestHenryMine No Response.
Mount Isa No Response.
Antamina No Response.
6. 4
Alumbrera No Response.
Freeport-
McMoRan
Sierrita,AZ No Response.
Bagdad,AZ No Response.
StrategicSourcingManager
For NorthAmerica
No Response.
StrategicSourcingManager
For SouthAmerica
Recentlychangedjobsandisno longerinvolvedwith
flotation.
Morenci, AZ Claimedlegal restrictions.
Codelco
RadomiroTomic Informedme of whichCodelcooperationswhere
involvedwithflotation.
El Teniente
Reportedusing2068 tonnesof frothers,705 tonnes or
collectorsand131.6 GWh of energywasconsumedby
the flotationprocesslastyear. Furtherattemptsto
inquire aboutpHadjustingagentsandsource of energy
consumedwere unsuccessful.
Chuquicamata No Response.
MinistroHales No Response.
El Salvador No Response.
Andina No Response.
OnlyCodelcosite leaderswouldrespondwithhelpful informationbutnotenoughinformationcouldbe
gatheredtomake assumptionsforothersiteslike Ihave done withpowerandwaterconsumption.
However,Ican make assumptionsonwhatkindor additiveswouldhave beenusedbasedonsome
commonknowledge. ItislikelythatforpH adjustmentslimeandsulfuricacid wouldbe used,aslime is
an industriallycommonbase material andsulfuricacidisoftenmade in subsequentstepslaterinthe
processof refiningmanymetals orearlierwhenroastingsulfidestooxides andwouldbe verycheap.
But dependingonlocationotherbase materialslike sodaashand/orcausticsoda maybe usedif itis
economical. While sulfuricacidcan be consideredsustainableasitis made fasterthan it isbeing
consumedduringmetal refining,lime isprimarilyobtainedbymininglimestone sothere isafinite
amountand as lime isusedinmanymetal refiningoperationsalongwithvariousotherapplicationsitis
almostcertainthat itwill runout before copperore depositsdo. The same isgenerallytrue forthe
productionof sodaash and causticsoda.
Most copperbearingore bodiestodayare some sort of sulfide,soprimarycollectingsurfactantswould
include anionicsulfurligands,suchasxanthate salts. These are made be reactingalcoholswithKOHand
CS2. Alcoholscanbe made ina varietyof mannersfromstarchesandsugars whichare sustainablebut
the latterreactantsare made from currentlyplentifulminerals,sointhe strictestsense are not
sustainable.
As forfrothers,mostare made fromnatural fats andoils,whichare of course sustainable andnearly
harmlesstothe environment. Otherfrothersare alcohol basedandas mentionedbefore are
sustainable aswell.
7. 5
2.3.Water
Water iskeypart of frothflotationasitacts as the mediuminwhichseparationoccurs,butwaterisa
keyelementtootheraspectsof civilizedsociety andbecause itisfreshwaterthatisbeingconsumed the
issue of sustainabilitymustbe addressed. Below inTable 3is an adjustedsummaryof the amountof
waterthe three companiesconsumedintheirflotationoperations.
Table 3. Water Consumption Reported from 2012 to 2015. Boxes with dashes meanno data could be foundfor that year.
Company 2012 (Mgal) 2013 (Mgal) 2014 (Mgal) 2015 (Mgal)
Codelco 80 78 84 -
Freeport-McMoRan - - 50927 65185
Glencore 3772 13978 13795 -
In 2014 alone these three companiesconsumedabout65 billiongallonsof freshwater,butthisishard
to numberto reallyunderstandwithoutputtingitintoperspective. BasedonWikipedia’sinformation
on waterdistribution thereisabout32x106
billiongallons of freshsurface wateronearth,thismean that
the total waterusedbythese companieswouldonlyaccountfora verysmall fraction,evenif we
considerthe hundreds of otherfrothflotationoperationaroundthe wateritisnotlikelytoaccountfor
more than one percentof the consumption. Andif we compare itto the amountof waterthat Glencore
usedinits variousotheroperationsnotrelatedtofrothflotation,whichtotaledabout71 billion gallons,
it wouldappearthatthe amountof waterconsumedbythisprocessisquite meager. However,the
issue of sustainabilitywithwaterdoesn’tcome downto consumedamountsalone,as the locationsand
situations of the areasaroundthese operations shouldalsobe considered. Inmostcasesflotation
operationsoccurinverydry areas,so obtainingthatmuchwater couldbe a problemforany civilizations
that live inthe same general areas. Andthoughthese operationsdotheirbesttorecycle andcleanas
much wateras the can before lettingitbackintothe watertable,the fact isthe waterwill still contain
potentiallyhazardouselementswhenthe operationisdone withit. Sofroman ethical standpointthese
operationare onlymarginallysustainable.
3. Alternative
These issuesinsustainabilityinparticularthe waterconsumption,are the drivingforcesbehindresearch
intoimprovementstothe currentprocessand alternative systems. One suchpossiblealternativewhich
I had the opportunitytoworkon at SouthDakota School of Minesand Technology includeswhatIwill
call frothlessflotation. The ideaistooessentiallyinverse the processof frothflotation,usingafluidized
bedreactor. In theory,airbecomesthe mediumthatsuspendsthe particlesandwatervaporswill
selectivelycondenseonparticlesincreasingtheirmassandforcinga separation.See Figure 1below.
8. 6
Figure 1. (Left) Froth flotation system, (Right) Alternative system.
Images takenfromhttps://en.wikipedia.org/wiki/Fluidized_bed_reactor and http://www.chinafote.com/pro/p21.html
Thisideadidn’tseemtohave beeninvestigatedbyanyone elsesothe researchIperformedwasinthe
veryearlystagesintothe conceptwiththe mainfocus beingon how the mineral surfacesare affected
by changesinrelative humidity. Afterexperimentingonmica, silicaandglassat various%RH there was
little indicationthathumidityhadanyeffectonwettabilityof these substrates. Sofurtherresearchinto
thistopicneedstobe done evenabenchscale device ismade.
4. Conclusion
Afterexaminationof power,chemical andwaterconsumptionthe followingisfairlyclear. Power
consumptionof frothflotationisactuallyquitelow comparedtootheraspectof the miningindustryand
isby no meansthe variable thatwouldlimitthisprocessessustainability. Chemical consumptioncould
limitthe sustainabilityof suchanoperationas the majorityof the material usedare non-sustainable
resourcesandare usedinvariousapplicationsbesidesfrothflotation. The ethical considerationsinto
the waterconsumptionof thisprocessare by far the mostlimitingaspectof thisprocesses
sustainability. The amountof waterconsumedisn’tnecessarilyacause forconcern,but giventhe
locationof these operationsitwouldbe easytounderstandwiththe growingenvironmental and
humanitarianmindsetthatthe world’spopulationisacquiringthatthese processesmaybe consuming
more than theyshould. So researchneedstobe done intomakingthe current processmore efficientor
developmentof alternatives.
9. 7
References
"Agua."Codelco.Codelco.Web.24Mar. 2016.
<https://www.codelco.com/agua/prontus_codelco/2011-07-11/110552.html>.
Bliewas,DonaldI.EstimatedWaterRequirementsforthe Conventional Flotationof CopperOres.
Reston,Virginia:U.S.Geological Survey,2012. Print. http://pubs.usgs.gov/of/2012/1089/pdf/ofr2012-
1089.pdf
Bliewas,DonaldI. Estimatesof ElectricityRequirementsforthe Recoveryof Mineral Commodities,with
ExamplesApplied toSub-SaharanAfrica.Reston,Virginia:U.S.Geological Survey,2011. Print.
http://pubs.usgs.gov/of/2011/1253/report/OF11-1253.pdf
Cobb,W. (2014). CDP2014 Water2014 InformationRequest.RetrievedJune 29,2015, from
http://www.fcx.com/sd/pdfs/ProgrammeResponseWater-2014.pdf
Cobb,W. (2015). CDP2015 Climate Change 2015 InformationRequest.RetrievedMarch23, 2016, from
http://www.fcx.com/sd/pdf/2015_CDP_Information_Request.pdf
"Energía."Codelco.Codelco.Web.24Mar. 2016.
<https://www.codelco.com/energia/prontus_codelco/2011-07-11/110731.html>.
Fisher,WalterW.,and Samuel Rudy.Utilizationof Municipal Waste WaterforFrothFlotationof Copper
and MolybdenumSulfides.Phoenix:Mineral TechnologyBranch,ArizonaBureauof Mines,1976. Print.
http://repository.azgs.az.gov/sites/default/files/dlio/files/nid1066/c17.pdf
Glencore SustainabilityReport2014. Rep.London:Deloitte,2015. Glencore,24 Apr.2015. Web.24 Mar.
2016. <http://www.glencore.com/assets/sustainability/doc/sd_reports/2014-Sustainability-Report-
additional-information.pdf>.
PBS,Incorporated.MiningIndustryEnergyBandwidthStudy.USDepartmentof Energy,2007. Web.5
Apr.2016. <http://www.energy.gov/sites/prod/files/2013/11/f4/mining_bandwidth.pdf>.
Acknowledgements
PalaciosEscobedoTito,site leaderof Codelco’sTenienteoperation,forprovidingdataonamountsof
consumablesandpowerthe site usedlastyear.
Hormazábal CádizErnestoA, site leaderof Codelco’sRadomi operation,forinformingwhichoperations
of Codelcoproduce concentrates byfrothflotation.
