Separating Copper From Scrap by Preferential Melting

7/22/2019 Separating Copper From Scrap by Preferential Melting

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809

crap

Evaluation

tiesMetallurgyResearchCenter,

yResearchCenter,Rolla,Mo.,and

tyMetallurgyResearchCenter,

MENTOFTHEINTERIOR

etary

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3

ptreatments6

eating8

gremarks9

3

ssion,andconclusions17

oppersweatingtests22

3,666,870,saltbathfurnaceforcopper

emper44

duction-heatedmoltensaltbath4

erselysectionedwithlamellaeremoved

eived,afterpretreatment,aftercopper

,stainlesssteelbasket,andcopperbutton,

paration8

ypicalsaltbathfurnace10

ndcavityofsalt bathfurnace11

athfurnacewithslidingcover12

marmaturesbysaltcoatingandsalt bath

marmaturesbysaltbathsweating15

beforetaxesasa functionofsellingprice

S04dipping-BaCl2sweating)21

mironin scraparmaturesbymolten-salt

tpretreatment6

eatingprocesses18

mariesfortheprocessesevaluated19

coveredcopperneededtomakedifferent

entbeforetaxes19

pwithbariumchloride22

pwithbariumchloride,sodiumsulphate

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pwithbariumchloride,sodiumsilicate

pwithcalciumchloride26

pwithcalciumchloride,sodiumsulphate

pwithcalciumchloride,sodiumsilicate

pwithbariumchlorideorcalciumchloride

27

pwithbariumchlorideandvariouspredip

mmaryforcopperrecoverybyNa2S04coating

ntling29

mmaryforcopperrecoverybyNa2S04coating

ng,anddrying30

maryforcopperrecoverybyNa2S04coating

stforcopperrecoverybyNa2S04coatingand

stforcopperrecoverybyNa2S04coatingand

stforcopperrecoverybyNa2Si03coating

stforcopperrecoverybyNa2Si03coating

stforcopperrecoverybyBaCl2sweating36

stforcopperrecoverybyCaCl2sweating37

ndoperatingpersonnelforcopperrecovery

Cl2sweating38


Cl2sweating39


Cl2sweating40


Cl2sweating41




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MSCRAPBYPREFERENTIALMELTING

Evaluation

e,2andHenryDolezal3

gcopperandsteelfrommetallicscraphasbeen

ofMinesbasedon preferentialmeltinginmoltensalt

C.Themoltensalt,preferablybariumchlorideor

nimizesoxidationofthemetalsandpromotesheat

tions(0.01percentcopperremaininginiron)have

tment(dippingorspraying)withsodiumsulphateor

ersandcoatsthesurfaceofthe irontoinhibitthe

pper.Aneconomicevaluationoftheprocesswas

tionsofsweatingmediaandinhibiting reagents.On

dmodel,acostofabout$0.20perpound ofcopper

minedforthesweatingtreatmentoperation.

ustryhasbeenamajorsegmentof thedomestic

secondarycommodities(heavymeltingsteelandlead

iarexamples)havebecomesowellestablishedand

ndustrycommitmentsformetalwouldbeimpossible

omerecoveryandrefiningprocessesdevelopedfor

edin scrap,thetechnologyonsecondarymetalrecla-

sonsforthislag.Difficultiesincollection,

drapidobsolescenceoffabricatedproductsare

ributingtothemountingaccumulationofsolid

ravatedbythegrowingcomplexityofmodernscien-

nology.Thecomponentsofhighlysophisticated

ndequipmentareoftenintricatecompositesofsev-

s,whicharealmostimpossibletoreclaimfromworn


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suallythesoleconsiderationindetermining

darymetalsfromparticularscrapcommodities.This

seatthemoment,butsociologicandecologicalimplica-

nthe future.Increasingpublicawarenessofcon-

encesoflandpollutionhasgeneratedpressureon

enttofindacceptablemeansofdisposingof or

mbinationofphysicalpropertiespossessedby

ompatibleforfabricationintovarioustypesof

usethecopperhashighelectricalconductivityand

highmechanicalandferromagneticstrength,they

matemechanicalcompositessuchasmotorarmatures,

copper-cladwire,etc.Aftertheusefulservice

enexpended,recoveryoftheironandcopper,as

ntsaproblem.Boththecleanhigh-siliconsteeland

highscrapvalues,buteachmaterialis adeleteri-

er.Assuch,a cleanseparationofbothmaterials

ceptbytediousand/or slowmethods.

tpresentsthe resultsofresearchonthe

fcopperandsteelfromscrapitemsin whichsubstan-

etalsarepresent.Thereare severalproceduresby

done,some ofwhicharepracticedcommercially.

leaching,mechanicalconcentrationssuchascrushing

anddisassemblingbyhandlabor.Leachingisan

ngcopperbutiseconomicalonlyonalarge scale.

yalsobecostlyor sufferfromshortcomingsin

ct.Anexcellentcompilationoftheseandother

condarycopperhasbeenpreparedbySpendlove.4

damethodforreclaimingthecomponentsofcopper-

es,someelectronicscrap,andgildingmetal;details

ontinuedresearchhasresultedin asignificant

gefficiency,particularlyforarmatures.

e EconomicEvaluationGroup,SaltLakeCity

ter,SaltLakeCity,Utah,fortheireconomicevalua-

idedthroughthecourtesyofA. F.HoldenCo.,

hroughthecourtesyofUptonIndustries,Inc.,

dsforProducingSecondaryCopper.BuMinesIC8002,

AnImprovedMethodfor SeparatingCopperand

ningFerrousScrap.SecondaryRawMater.,v.6,


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N

dseemtobeanappropriatemeansfor separating

ngthewidespreadin meltingpoints(1,083 and

ly).Sweatingtechniquesareeffectiveinreclaim-

metals--suchaslead,tin,zinc,andaluminum--and

rsometime.However,experimentsingaseouscombus-

ordinarysweatingprocedureswerenotsatisfactoryfor

wingtooxidationofironand entrapmentofcopper

ducingatmospherediminishesscalingbutenhances

alloywithiron.

discoveredthatif thesweatingis

moltensubstancesuchasbariumchloride,bothoxida-

andiron arelessened,andtheliquidbath

fer.Althoughthisconstitutedaconsiderable

ore(asinscraparmatures)still retainedseveral

tly,analmostquantitativeseparationwasachieved

micalreagentsthatalterandcoatthesurfaceof the

razing inthemoltenbath.In effect,abar-

the steelsurfacetopreventintimatecontactof

owsoverthesurfaceofthearmature.Theexact

umberofsmall (1-3/4-inch-diameter)armatures

dsolutionsofsodiumsulphate(5 toabout40percent

e)orsodiumsilicate(about40to 60percent)andthen

eimmersiontimeisnot critical.Thismayalsobe

gthesolutiononthescrapor byimmersingcompletely

ningabout4poundsofthe salt,whichcom-

ngmedium,wasplacedintothelaboratoryinduction

ewasbroughtupto theselectedoperatingtem-

,or1,250 Casmeasuredwithanopticalpyrometer.

tedaspreviouslydescribed,wasplacedinthemolten

lowedtoattainequilibriumtemperature.This

2minutesafterwhichthearmaturewassoakedfor

angedfrom2to 15minutes.Copperdropletsare

collectedinthe bottomofthevessel;theliquid

pedfromavessel ofcommercialsize.Thearmature

tongs andshakentoremovesomeofthemoltencopper

maturewasremovedfromthesaltbath anddropped

ovemoremolten copperfromthecrevicesofthe

at transfermediummaybereclaimedandreused

teelweremadebycuttingthe armatureinhalf,

movingseveraltypicalsteellaminaeinalathe orby

alyseswereperformedonthesampledlamellae.


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reintoinduction-heatedmoltensaltbath,

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e:Transverselysectionedwithlamellaeremoved


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ntable1, andphotographsoftreatedanduntreated

e3.

opperfromironin scraparmaturesby

handwithoutpretreatment


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es:Asreceived,afterpretreatment,aftercopperseparation.


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ndsisasfollows:Brazeinhibitorpaint-titanium

ibitorpaint-calciumcarbonatepigment,sodium

ride,vanadiumpentoxide,ammoniummolybdate,ammonium

diumphosphate,sodiumborate,andtinchloride.

gwas concentratedonsulphatesandsilicatesas

dnumberoftests wereexecutedwiththeseother

heresultsdo notappeartobeas successfulas

sulphateinhibitors,butinviewof thelimited

gardedasbrazing inhibitors.Additionaltesting

valuatetheir effectiveness.

eating

umchloridesweatingtechniquewasevaluated

r-containingmaterials.Basketsweatingtestswere

eelectroniccomponents(fig.4).

ponents,stainlesssteelbasket,andcopperbutton,beforeand

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nlesssteelbasketswereusedto sweatseveral

mponentsabout5minuteseachat1,250 C.Acom-

ebatcheswasproduced,whichaccountedfor

eightwith 0.9percentironastheonly objectional

UDINGREMARKS

tingseparationisbasedon closetemperature

pointofonemetal butbelowthatofthe other.In

enbathnot onlyfacilitatestemperaturecontrolbut

erandlimitsoxidation.Thepurposeof thepre-

steellesssusceptibletoalloyingwithcopper

xidation(asin thecaseofsodiumsulphate)orby

ithanonreactivesubstance(asinthe caseof

nbathswere,asnotedearlier,anhydrousbarium

e.Commercialheat-treatingsaltsforhigh-speed

ssfully;theseareproprietarymixtureswithbarium

ponent.Thebathsarenot limitedtothesesub-

hemoltenbathsmaybeanysalt,slag,or glass,

stable,noncorrosive,relativelyinexpensive,

wvaporpressure,andformsafluid meltinthe

range.Similarly,thepretreatmentcouldbeeffected

hemicals,whichwouldrenderthesteellesssus-

pperandis compatiblewiththebalanceofthe

eninthe choiceofsaltmixturessincesomecombina-

emitpoisonousgases.

gdemandfor copperovertheprojected

nanescalatingpricetag,recoveryof copperfrom

beencouraged.Thetechniquedescribedisaworkable

erandsteelfromscrapcommoditiesinwhichtheseare

rearesomelimitationsonthe methodthatmustbe

mitationsisthecoppercontentofthe electrical

enoughtobear virtuallyalltheprocessingcosts.

gfactoristhephysicalstructureofthe scrap;it

oallowthe freeflowofmoltensaltandmetal and

constructedastoretainsubstantialquantitiesof

cessshouldposeno unusualequipmentproblems

mercialsize.Theeconomicshavebeenevaluated

apableof recovering1tonofcopperperday.In

erispresumedto beabyproductofafairly large

d,butthemodelwouldbeequallyappropriateforother

actionalhorsepowermotors.Theseparating

ed-electrode,salt-potfurnaces,whichcouldbe

continuousdischargeofcopper.Theseinternally

cefurnaces,availablefromseveralsuppliers


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wingoftypicalsalt bathfurnace.(CourtesyofA.F,HoldenCo.)


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ectrodesandcavityofsaltbathfurnace.

o.)

t treatmentofhigh-speedsteelarticlesandare

viceattemperaturesupto1,300 C.


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estimateare(1) tocomparethemeritsof

mchlorideasneutralbathsforsweatingcopperfrom

aturesand(2)to assessthevalueofcoatingthe

diumsulfateand sodiumsilicatesolutionspriorto

swillalsoprovideabasisfor comparingthis

dsforseparatingcopperandsteelin scrapmaterials.

othedistribution ofcosts,theprocesses

perationsof dismantling,dipping,andsweating.

hebasisof averysmalloperationbecauseofthe

andgeneratorsavailableatany onelocation.

thefactthatthesweatingplantwouldprobablybe

yard,specialconditionscouldeasilyexist that

edcostsconsiderably.However,comparisonbetween

ocessshouldbevalid.

processes,ofwhichthreeemploya molten

weatingthecopperandthree employmoltencalcium

eeprocessesincludesthefollowingvariations:

maturesbydippingin sodiumsulfate,(2)pre-

tesolution,and(3)no pretreatment.Theflow-

sareshownin figures8-9.

tersandgeneratorsmust bepartially

opperparts.First,theend platesareremovedby

peed wrench.Thisreleasesthearmaturesfor

halfthestartershavecast-ironsolenoidlinkage

kenwitha hammertoreleasethearmatures.In

thsofthestarterarmaturesmusthaveoneend of

ethebendixspringandendplate.This ismost

dsaw.Thestarterswithsolenoidlinkagesalso

mustbeopenedby cuttingwithanacetylenetorchto

eldcoilsarebrokenloosefrom thestatorhousing

movethecopperwindings.Copperbushingsand

edbyhand.

ninearmaturesareloadedinto amultiple-

automaticallygripstheshaftendswhen themechanism

Whileheldinthis mechanism,thearmaturesare

lt-bathfurnacecontaininga12-inch-squareby

nbariumchlorideorcalciumchlorideatapproxi-

owedthatthecoppermeltsand dropstothebottom

es;consequently,9minuteswasassumedtobe

g,sweating,andremovingthearmatures.After

andsaltisshakenloosein avibratingscreenand

ltadheringto thearmaturesisnotrecovered.


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om


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om

pperfromarmaturesby saltbath

marketableasNo.2heavymelt

minatedarmatures.However,


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ulfateandsweatedin bariumchloridewouldbe

sethesellingpriceof copperrequiredforagiven

0.02perpound.The copperproductincludesmanually

withsweatedcopper.

atingisintendedfor usewithcompletechemical

wever,theresultsobtainedappeartobereasona-

ithsmall-scaleconstructioninsuchanenvironment.

mall,andtheusual roundoffofcoststothe

and thenearest$1,000fortotalcostswouldhave

tdiscrepancies.Thesediscrepancieswereavoidedby

arestdollar.Becausethiswasdoneonlyforcon-

akento indicateahighdegreeofaccuracy.

pitalcostsshouldbewithin30percent.

edonthe deliveredcostofindividualitems

sarefor1971and correspondtoanM&Saverage

321.3.

oncostforeachunitoperationconsistsof

ipmentplus thecostoflaborto erectitandthe

tionrequiredtosupport,house,protect,andmake

constructioncostswereestimatedbyfactors

edcostof equipmenttobeinstalled.Amiscella-

dtocoverminor equipmentorconstructionthatmight

tnotrequiringinstallation,whichinthiscaseis a

rtofthedirectconstructioncostwithoutinstalla-

nofconstructionfactors.Thisforkliftisused

ebalanceofthetime itwouldbeusedin thescrap

eighththecostoftheforkliftis chargedtothese

rectconstructioncostwasaddedas indirect

e.Thisapproximatestheadditionof10percentfor

thefollowingpercentagesofsuccessiveresulting

gplus5 foradministrationandoverhead,10for

ontractor'sfees.Thefieldindirectcostcovers

on,temporaryconstruction,equipmentrental,and

cilitieswasestimatedas 10percentofthe

eproductionunits.These facilitiesinclude

oroffices,shops,andwarehouses,plusfencing,

ties,andsafetyequipment.

MarshallandStevensEquipmentCostIndex.V.76,

4-138.


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21/27

ntforsweatingprocesses


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ostsummariesfortheprocessesevaluated

ting

ting

ting

ting

ing..

ing..

extractedfromtablesA-18throughA-23intheappendix,

cesforrecoveredcopperneeded

eturnon

dollars

ting

ting

ting

ting

ing..

ing..

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tionswerecausedbyminordifferencesinthecost

2,andCaCl2.Operatingcostsforthetwo processes

ereconsiderablylower,primarilybecauseoneless

also,toa lesserextent,becausethesaltdipwas

atingcostswerecalculatedontheassumptionthat

of ascrapyardandthatthe startersandgenera-

egligiblecost.Theseunits were,therefore,

th$0.00cost.However,iftheyhadtobe

veredwouldbebetween$20and$60per ton.The

ratorsandstarters hasonaprocesscanbe shown

priceofrecoveredcoppertoobtaina givenrate

foretaxes.Theeffectwasevaluatedovera range

hofthesesixprocesses,andthe dataweresimilar.

fectforNa2S04dipping andBaCl2sweatingis

lotshowsthatifthe copperproductcanbesold

ereturnoninvestmentbeforetaxeswouldnotbe more

onwereassignedto thecostofgeneratorsand

btain areturnoninvestmentof20 percent,the

ouldhavetobe purchasedatabout$15perton.This

seprocessestoscrapyardsthatrecovertheirown

esstoautomobilegeneratorsandstarters

efeaturesofcopperremovalbysweatingbecause

ostsarein dismantling.Datafromthesweating

edasa basisforestimatingthetreatmentcostof

materialsthatdonotrequireasmuchpreliminary

dgenerators.


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GENERATORS

ton

estmentbeforetaxesas afunctionofsellingpriceand

4dipping-BaCI2sweating).


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COPPERSWEATINGTESTS

perscrapwithbariumchloride


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perscrap withbariumchloride,


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n,Google-digitized

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Separating Copper From Scrap by Preferential Melting

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