METHOD FOR THE MANUFACTURE OF ZAN-AL-ALLOYS

Description

BE2024 / 5970 2 conservesrawmaterialsbutalsoreducesenergyconsumption;recycledaluminium requires95%lessenergythanprimaryaluminiumproduction,whilerecycledzincuses60- 75%lessenergy.Asenvironmentalregulationstightenandindustriesstriveforcircular economies,theabilitytoefficientlyrecycleAl-Znalloys,withAlaccountingforthelargest share,aswellasZn-Alalloys,withZnaccountingforthelargestshare,willbeparamount5 inmeetingbotheconomicandenvironmentalgoals. CN101629244AdisclosesamethodforregeneratingandseparatingAlandZn fromawasteAl-Zn-Fe-Sialloy.Accordingtothismethod,thewasteAl-Zn-Fe-Sialloyisfirst preheatedat500–700°C.Azincfluxmaterialisseparatelyheatedatitsmelting temperature.Afterthezincfluxmaterialiscompletelymelted,thepreheatedwaste10 aluminium-zinc-iron-siliconalloyisaddedtothemoltenzincsolution,whereinthemass ratioofthezincfluxtothealloyiscontrolledtobe2to64.Afteraddition,themixtureis keptatatemperatureof450°Cto750°C.Subsequently,aslagisremovedtoobtaina liquidzinc-aluminiumalloy,whichisthenfurtherseparatedusingvacuumdistillation. Acrucialaspectoftherecyclingofalloyscontainingmainlyzincandaluminiumis15 thattheconcentrationofimpurities,andmoreinparticularofiron(Fe),iskepttoa minimumintherecycledalloycomposition.Indeed,assuchcompositionsareusedin applicationsrequiringhighcorrosionresistance,brittleintermetallicZn-Al-Fecompounds maynotonlyleadtopoormechanicalperformance,butalsopossiblytoreduced corrosionresistance.20 Basedontheabove,thereremainsaneedforamethodforrecyclingZnandAl fromawastemetalalloymaterialcontainingFe,intoaZn-Alalloy,orintoanAl-Znalloy,havinglowconcentrationsofimpurities.Thepresentinventionaddressesthesechallenges byprovidinginnovativemethodsforimprovingtherecyclingefficiencyandqualityof secondaryalloyscontainingmainlyzincandaluminium.25 2024 / 5970 BE2024 / 5970 3 SUMMARYOFTHEINVENTION Theinventorshavesurprisinglyfoundthattheprocessaccordingtothepresent inventionfulfilstheabovementionedneedsandovercomestheabovementioned disadvantages. 5 Inanaspectofthepresentinvention,thereisprovidedamethodformanufacturinga metalalloycompositioncomprisingaluminium(Al)andzinc(Zn),whereinthemethod comprisesthefollowingsteps: a)providingafeedcompositioncomprising,relativetothetotalweightof thefeedcomposition:10 -from50.00to95.00wt.%ofaluminium;and -from0.25to5.00wt.%ofiron(Fe); b)mixing,atatemperaturerangingfrom450°Cto850°C,saidfeed composition,inafirstfurnaceandinthepresenceofatleastoneflux,withanamount ofaliquidmoltenmetalcomposition,thelattercomprising,relativetothetotalweight15 ofsaidliquidmoltenmetalcomposition,anamountofzincequaltoorhigherthan 80.00wt.%,soastoformafirstliquidmoltenmetalphaseandafirstsupernatant drosswhichundertheinfluenceofgravitycomesfloatingontopofsaidfirstliquid moltenmetalphase,andwhereintheamountofsaidliquidmoltenmetalcomposition isselectedsuchthatthefirstliquidmoltenmetalphasecomprises,relativetothetotal20 weightofsaidfirstliquidmoltenmetalphase,from10.00to40.00wt.%ofaluminium; c)coolingthefirstliquidmoltenmetalphase,optionallyafteratleast partialremovalofthefirstsupernatantdross,inthefirstfurnacetoatemperature lowerthanthetemperatureofmixinginstepb)soastoformasecondliquidmolten metalphaseandasecondsupernatantdrosswhichundertheinfluenceofgravity25 comesfloatingontopofsaidsecondliquidmoltenmetalphase; d)transferringthesecondliquidmoltenmetalphase,optionallyafterat leastpartialremovalofthesecondsupernatantdross,fromthefirstfurnacetoa secondfurnace,soastoformathirdliquidmoltenmetalphaseandathird supernatantdrosswhichundertheinfluenceofgravitycomesfloatingontopofsaid30 thirdliquidmoltenmetalphase; 2024 / 5970 BE2024 / 5970 4 e)atleastpartiallyremovingthethirdsupernatantdrossfromthethird liquidmoltenmetalphase; f)heatingthethirdliquidmoltenmetalphaseinthesecondfurnacetoa temperaturerangingfrom600°Cto800°Csoastoformafourthliquidmoltenmetal phaseandafourthsupernatantdrosswhichundertheinfluenceofgravitycomes5 floatingontopofsaidfourthliquidmoltenmetalphase; g)atleastpartiallyremovingthefourthsupernatantdrossfromthe fourthliquidmoltenmetalphaseinthesecondfurnace;and h)castingthefourthliquidmoltenmetalphasefromthesecondfurnace intoatleastonemouldtherebyprovidingthemetalalloycompositioncomprising10 aluminiumandzinc. Itisanadvantageoftheinvention,thatametalalloycompositioncomprising aluminium(Al)andzinc(Zn)canbeproduced,whereintheconcentrationofimpurities, suchasiron(Fe),canbereducedtoaminimum,whilecoveringawideZn / Alratioin themanufacturedmetalalloycomposition.15 Inembodimentsaccordingtotheinvention,saidfeedcompositionfurther comprises,relativetothetotalweightofthefeedcomposition,from5.00to15.00 wt.%ofzinc. Inembodimentsaccordingtotheinvention,saidatleastonefluxisselected from:ZnS,ZnCl2,NH4Cl,(NH4)2ZnCl4,aswellashydratesandmixturesthereof.20 Itisanadvantageoftheseembodiments,thatsaidatleastonefluxsupportsthe purificationoftheliquidmoltenmetalphasesproducedduringtheelaborationofthe method,ofundesiredcomponentsandchemicalimpuritiesascomprisedtherein. Inembodimentsaccordingtotheinvention,saidatleastonefluxisaddedtosaid mixtureofsaidfeedcompositionandsaidliquidmoltenmetalcomposition,and / or25 presentinsaidfirstliquidmoltenmetalphase,inanamountofpreferablyatmost0.50 wt.%,withrespecttothetotalweightofsaidfirstliquidmoltenmetalphase. Inembodimentsaccordingtotheinvention,saidfirstliquidmoltenmetalphaseis cooledinthefirstfurnacetoatemperature,whichisfrom420°Cto600°C. 30 2024 / 5970 BE2024 / 5970 5 Inembodimentsaccordingtotheinvention,saidtransferofsaidsecondliquid moltenmetalphaseisexecutedbyuseofaladle. Inembodimentsaccordingtotheinvention,themethodfurthercomprisesthe followingsteps: i)subjectingatleastoneofsaidremovedfirstsupernatantdross,second5 supernatantdross,thirdsupernatantdrossand / orfourthsupernatant drosstoatleastonecrushingstepandatleastonesortingstepfor separatingatleastoneAluminium-Zincfractionfromthesaidfirst, second,thirdand / orfourthsupernatantdross; j)addingtheatleastoneAluminium-Zincfractionobtainedinstepi)tostep10 b)soastocontributetoprovidingthefeedcompositionofstepa). Itisanadvantageoftheseembodiments,thatAlandZnthatarepresentinthe drossesformedduringtheelaborationofthemethod,canberecovered,therebyreducing lossofpreciousmaterials. Inembodimentsaccordingtotheinvention,themethodfurthercomprisesthe15 followingsteps: g’)adding,priortosteph),atleastonefurthermetalcomponentstream tosaidfourthliquidmoltenmetalphaseinthesecondfurnace. Itisanadvantageoftheseembodiments,thatthecompositionofthefinal productcanbecontrolledtoahighdegree.20 Inembodimentsaccordingtotheinvention,saidatleastonefurthermetal componentstreamcontainsatleast50wt.%ofAl,withreferencetothetotalweightof saidatleastonefurthermetalcomponentstream. Itisanadvantageoftheseembodiments,thattheconcentrationofAlcanbe increased,sothatafinalproductcanbeobtained,whichcanbeaZn / Alalloyaswellasan25 Al / Znalloy. Inembodimentsaccordingtotheinvention,saidfeedcompositioniscomposed ofororiginatedfromoneormoresecondaryfeedstocks. 30 2024 / 5970 BE2024 / 5970 6 DETAILEDDESCRIPTION Inthecontextofthepresentinvention,theterm“comprising”shouldnotbe interpretedasexcludingfeaturesorelementsotherthanthoseexplicitlymentioned.It shouldbeconstruedasspecifyingthepresenceofthefeaturesorelementsindicated,but doesnotexcludethepresenceoradditionofoneormoreotherfeaturesorelements.5 Thus,thescopeoftheexpression"amethodcomprisingstepsAandB"shouldnotbe limitedtomethodsconsistingonlyofstepsAandB.Similarly,acompositioncomprising componentsAandBshouldnotbelimitedtocompositionsconsistingonlyofcomponents AandB.Accordingly,theterms"comprising"and"including"encompassthetermsmore restrictive“consistingessentiallyof”and“consistingof”.10 Inthecontextofthepresentinvention,ifanelementorcomponentissaidtobe selectedfromalistofrecitedelementsorcomponents,itshouldbeunderstoodthatthe elementorcomponentcanalsobeanyoneoftheindividualrecitedelementsor componentsinsaidlist,orcanalsobeselectedfromagroupconsistingofanytwoor moreoftheexplicitlylistedelementsorcomponents.15 Anaspectoftheinventionrelatestoamethodformanufacturingametalalloy compositioncomprisingaluminium(Al)andzinc(Zn),whereinthemethodcomprises thefollowingsteps: a)providingafeedcompositioncomprising,relativetothetotalweightofthe20 feedcomposition: -from50.00to95.00wt.%ofaluminium;and -from0.25to5.00wt.%ofiron(Fe); b)mixing,atatemperaturerangingfrom450°Cto850°C,saidfeed composition,inafirstfurnaceandinthepresenceofatleastoneflux,with25 anamountofaliquidmoltenmetalcomposition,thelattercomprising, relativetothetotalweightofsaidliquidmoltenmetalcomposition,an amountofzincequaltoorhigherthan80.00wt.%,soastoformafirst liquidmoltenmetalphaseandafirstsupernatantdrosswhichunderthe influenceofgravitycomesfloatingontopofsaidfirstliquidmoltenmetal30 phase,andwhereintheamountofsaidliquidmoltenmetalcompositionis 2024 / 5970 BE2024 / 5970 7 selectedsuchthatthefirstliquidmoltenmetalphasecomprises,relativeto thetotalweightofsaidfirstliquidmoltenmetalphase,from10.00to40.00 wt.%ofaluminium; c)coolingthefirstliquidmoltenmetalphase,optionallyafteratleastpartial removalofthefirstsupernatantdross,inthefirstfurnacetoatemperature5 lowerthanthetemperatureofmixinginstepb)soastoformasecond liquidmoltenmetalphaseandasecondsupernatantdrosswhichunder theinfluenceofgravitycomesfloatingontopofsaidsecondliquidmolten metalphase; d)transferringthesecondliquidmoltenmetalphase,optionallyafteratleast10 partialremovalofthesecondsupernatantdross,fromthefirstfurnacetoa secondfurnace,soastoformathirdliquidmoltenmetalphaseandathird supernatantdrosswhichundertheinfluenceofgravitycomesfloatingon topofsaidthirdliquidmoltenmetalphase; e)atleastpartiallyremovingthethirdsupernatantdrossfromthethirdliquid15 moltenmetalphase; f)heatingthethirdliquidmoltenmetalphaseinthesecondfurnacetoa temperaturerangingfrom600°Cto800°Csoastoformafourthliquid moltenmetalphaseandafourthsupernatantdrosswhichunderthe influenceofgravitycomesfloatingontopofsaidfourthliquidmolten20 metalphase; g)atleastpartiallyremovingthefourthsupernatantdrossfromthefourth liquidmoltenmetalphaseinthesecondfurnace;and h)castingthefourthliquidmoltenmetalphasefromthesecondfurnaceinto atleastonemouldtherebyprovidingthemetalalloycomposition25 comprisingaluminiumandzinc. Advantageously,bymixingthefeedcompositionwithanamountofaliquid moltenmetalcompositionatthetemperaturesindicatedabove,theresultingfirstliquid moltenmetalphase(whichthusincludesthe(Al+Fe)-containingfeedcompositiontobe30 purifiedandwhichnowhasZnforcomponentwiththehighestconcentration),canbe 2024 / 5970 BE2024 / 5970 8 processedatlowertemperaturesthanwouldberequiredforthefeedcompositionwhen processedalone.Indeed,aspureZnmeltsatatemperatureofaround420°Candpure aluminiumatatemperatureofaround660°C-withFemeltingatevenhigher temperatures-,apurifiedZn-Alalloycompositioncanbeobtainedhavingareduced concentrationofiron.ByshiftingtowardsamoltenmetalphasecontainingZnasmajor5 component,ithasbeenfoundthatthehighaffinityofAlforFeallowsforforminga separateandlighterphasewithregardtotheZn-Alphase,whereintheformerphase(Al- Fe)movestowardsthesurfaceasadross.Extractionofimpurities,moreinparticulariron (Fe)impurities,isthusfacilitatedbythetransferofsaidimpuritiestothesupernatant drossphasesformedduringseveralstepsoftheprocess.Theinventorshavemoreover10 foundthatthemethodaccordingtotheinventionallowsforobtainingaZn-Alalloy,havingalowconcentrationofimpurities,notablyofFe.Withoutbeingboundtothis theory,itisassumedthatthecombinationofheating,cooling,transferandheating,leads totheformationofslags,resultinginaZn-Alalloyhavingarelativelyhighpurity. 15 Inthisdocumentandunlessspecifiedotherwise,amountsofmetalsandoxides areexpressedinaccordancewiththetypicalpracticeinpyrometallurgy.Thepresenceof eachmetalistypicallyexpressedinitstotalpresence,regardlesswhetherthemetalis presentinitselementalform(oxidationstate=0)orinanychemicallyboundform, typicallyinanoxidizedform(oxidationstate>0).Forthemetalswhichmayrelatively20 easilybereducedtotheirelementalforms,andwhichmayoccurasmoltenmetalinthe pyrometallurgicalprocess,itisfairlycommontoexpresstheirpresenceintermsoftheir elementalmetalform,evenwhenthecompositionofaslagisgiven,inwhichthemajority ofsuchmetalsmayactuallybepresentinanoxidizedform.Forthisreason,the compositionofadrossorslag,suchasthoseobtainedintheprocessaccordingtothe25 presentinventionspecifiesthemetalcontentaselementalmetals. Withinthecontextofthepresentinvention,theterm“pyrometallurgy”relatesto abranchofmetallurgythatinvolvestheextractionandrefinementofmetalsfromtheir oresorothermaterials,suchasalloys,e.g.forthepurposeofrecycling,usinghigh- temperatureprocesses.30 2024 / 5970 BE2024 / 5970 9 Withinthecontextofthepresentinvention,theterm“supernatantdross”is intendedtodenoteanoftenlighterandtypicallypaste-likesubstancethatformsasa resultofanoperationalstep,andthatseparatesfromadenser“liquidmoltenmetal phase”,usuallyundertheinfluenceofgravity,andusuallycomesfloatingontopofsaid liquidmoltenmetalphase.Itwillbeappreciatedbythepersonskilledintheartthatsuch5 adrossmaybereferredto,orhasbeenreferredtoinpriorart,bythewording“slag”, “ashes”,or“skimmings”.Suchexpressionsinthepriorartmaybeconsideredtofallwithin thedefinitionaboveofdross.Asusedherein,thewording“ashes”willhoweverrefertoa componentwhichispotentiallypresentinadross. Asupernatantdrossisusuallyabletobemechanicallyscrapedofforremoved10 fromtheunderlyingliquidmoltenmetalphase.Thesupernatantdrossisusuallyrichin variousundesiredcomponents,suchasashes,andmetaloxides(suchasoxidesfromFe, AlandZn).Thesupernatantdrosscanstillcontainasignificantamountoftheliquid moltenmetalphase,thelatterbeingtrappedinsaidsupernatantdross. Withinthecontextofthepresentinvention,theterm“liquidmoltenmetal15 phase”isintendedtodenoteadenserliquidmoltenmetalphasethatformsasaresultof anoperationalstep,andthatseparatesfromasupernatantdrossusuallyunderthe influenceofgravity.Saidliquidmoltenmetalphasecomprisesrelativelyfewofthe undesiredcomponents,suchasashesandmetaloxides,ascomparedwithsaid supernatantdross,astheseundesiredcomponentsarenowatleastpartiallycomprisedin20 thesaidsupernatantdross. Ingeneral,apersonskilledintheartisfamiliarwithavailableanalysistechniques fordeterminingthechemicalcompositionofsecondaryfeedstockswithregardtothe presenceofaluminium,zincandothermetalcomponents.Non-limitingexamplesofsuch analysistechniquesareorganoleptictechniques,andopticalemissionspectroscopy(OES).25 Inafirststepa)ofthemethodaccordingtotheinvention,afeedcompositionis provided,whereinthefeedcompositioncomprisesaluminium(Al)andfurthercomprises iron(Fe). Withinthecontextofthepresentinvention,itisthereforeunderstoodthatsaid30 feedcompositionisprovidedinsuchawaythatsaidfeedcompositioncomprises 2024 / 5970 BE2024 / 5970 10 aluminium(Al)andfurthercomprisesiron(Fe).Thealuminiummaybecontainedinthe feedcompositionintheformofanaluminiummetalalloy.Theiron(Fe)maybecontained inthefeedcompositionintheformofanironmetalalloy. Withinthescopeofthepresentinvention,suchafeedcomposition,asdetailed above,maybeprovided,i.e.becomposed,fromoneormoresecondaryfeedstocks,also5 knownasrecyclablematerials,optionallycombinedwithoneormoreprimarysources. Thesesecondaryfeedstocks,alsoknownasrecyclablematerials,maycomefrom awidevarietyofsourcesandthereforecompriseawidevarietyofcompounds.Recyclable materialsmayforinstancebeby-products,wastematerialsandend-of-lifematerials. Moreover,itisknownthatsecondaryfeedstockshavea(significantly)lowercarbon10 footprintcomparedtoprimaryrawmaterials. Inembodimentsaccordingtotheinvention,saidoneormoresecondary feedstocksmayrelatetoaslag,skimmingsordrossresultingfromametallurgicalprocess, moreinparticularaswasteslag,skimmingsordrossfromametallurgicalprocess. Inembodimentsaccordingtotheinvention,priortostepb)ofthemethod,said15 feedcompositionissubjectedtoatleastonecrushingstepandatleastonesortingstep. Saidatleastonecrushingstepinvolvessystematicallybreakingupsaidfeedcomposition, usingcrushingmeans,whereinsaidcrushingmeansarepreferablyselectedfromteeth, blades,spines,oranycombinationthereof,intoaparticulatematerialofadifferent particlesize.Saidparticulatematerialmaythenfurthersubjected,duringoraftertheat20 leastonecrushingstep,toatleastonesortingstep,whichatleastonesortingstepis preferablyrelatedtosieve-basedseparation. Inalternativeembodimentsaccordingtotheinvention,priortostepb)ofthe method,saidfeedcompositionissubjectedtosaidatleastonesortingstep,providedthat saidfeedstockalreadyconsistsofaparticulatematerialwithsmallparticlesthatcanbe25 processedininstepb). Accordingtotheinvention,saidfeedcompositioncomprises,relativetothetotal weightofthefeedcomposition,from50.00to95.00weightpercentage[wt.%,herein after]ofaluminium.Preferably,saidfeedcompositioncomprisesatleast50.00wt.%,30 morepreferablyatleast55.00wt.%,evenmorepreferablyatleast60.00wt.%, 2024 / 5970 BE2024 / 5970 11 preferablyatleast65.00wt.%,morepreferablyatleast70.00wt.%,evenmore preferablyatleast75.00wt.%,preferablyatleast85.00wt.%,andmostpreferablyat least85.00wt.%ofaluminium,withreferencetothetotalweightofthefeed composition.Itisfurtherunderstoodthatsaidfeedcompositioncomprisespreferably atmost95.00wt.%,morepreferablyatmost94.00wt.%,evenmorepreferablyat5 most93.00wt.%,preferablyatmost92.00wt.%,morepreferablyatmost91.00wt.% andmostpreferablyatmost90.00wt.%ofaluminium,withreferencetothetotal weightofthefeedcomposition. Accordingtotheinvention,saidfeedcompositioncomprises,relativetothe totalweightofthefeedcomposition,from0.25to5.00wt.%ofiron.Preferably,said10 feedcompositioncomprisesatleast0.25wt.%,morepreferablyatleast0.30wt.%, evenmorepreferablyatleast0.35wt.%,andmostpreferablyatleast0.40wt.%of iron,withreferencetothetotalweightofthefeedcomposition.Itisfurther understoodthatsaidfeedcompositioncomprisespreferablyatmost5.00wt.%,more preferablyatmost4.00wt.%,evenmorepreferablyatmost3.00wt.%,preferablyat15 most2.00wt.%,andmostpreferablyatmost1.00wt.%ofiron,withreferencetothe totalweightofthefeedcomposition. Inembodimentsaccordingtotheinvention,saidfeedcompositionfurther comprises,relativetothetotalweightofthefeedcomposition,from5.00to15.00 wt.%ofzinc.Preferably,saidfeedcompositioncomprisesatleast5.00wt.%,more20 preferablyatleast6.00wt.%,evenmorepreferablyatleast7.00wt.%,preferablyat least8.00wt.%andmostpreferablyatleast9.00wt.%ofzinc,withreferencetothe totalweightofthefeedcomposition.Itisfurtherunderstoodthatsaidfeed compositioncomprisespreferablyatmost15.00wt.%,morepreferablyatmost14.00 wt.%,evenmorepreferablyatmost13.00wt.%,preferablyatmost12.00wt.%,and25 mostpreferablyatmost10.00wt.%ofzinc,withreferencetothetotalweightofthe feedcomposition. Inembodimentsaccordingtotheinvention,saidfeedcompositionfurther comprisesotherelements,whichmayrelatetometals,metalloidsornonmetalsand whereinthesumofsaidotherelementsislessthan10.00wt.%,preferablylessthan8.0030 wt.%,morepreferablylessthan6.00wt.%,evenmorepreferablylessthan4.00wt.%, 2024 / 5970 BE2024 / 5970 12 preferablylessthan2.00wt.%,andmostpreferablylessthan1.00wt.%,relativetothe totalweightofthefeedcomposition. Inasubsequentstepb)ofthemethodaccordingtotheinvention,saidfeed compositionismixedinafirstfurnacewithanamountofaliquidmoltenmetal5 composition.Theorderinwhichthetwocomponentsareaddedtothefirstfurnaceis thereinflexible. Inembodimentsaccordingtotheinvention,saidliquidmoltenmetal compositioncanbeintroducedinsaidfirstfurnacefirst,followedbytheadditionof saidfeedcompositiontosaidliquidmoltenmetalcompositionandbythemixingof10 bothcomponentsinsaidfirstfurnace. Inalternativeembodiments,saidfeedcompositioncanbeintroducedinsaid firstfurnacefirst,followedbytheadditionofsaidliquidmoltenmetalcompositionto saidfeedcompositionandbythemixingofbothcomponentsinsaidfirstfurnace. Preferably,thecomponentthatisaddedfirsttosaidfirstfurnaceisinsolid15 state,preferablyatambienttemperature,andisheatedinsaidfirstfurnacetoaliquid state,priortoaddingthesecondcomponent.Saidsecondcomponentispreferablyin solidstate,preferablyatambienttemperature,andmeltsuponadditiontothefirst furnacecontainingthemoltenfirstcomponent.Preferably,themetalcompositionis introducedinsolidformandsubsequentlymolteninthefirstfurnace,thereby20 transformingintosaidliquidmoltenmetalcomposition.Saidfeedcompositionis subsequentlyadded,preferablywhilebeingatambienttemperature. Alternatively,atleastoneofsaidcomponentscanbepreheatedpriorto addingtosaidfirstfurnace,atthestartand / orduringtheprocess. Saidliquidmoltenmetalcompositionmaybepreheatedandaddedtothefirst25 furnaceinliquidform,atthestartand / orduringtheprocess,preferablyata temperatureofbetween400°Cand500°C.Saidfeedcompositionmaybepreheated andaddedtothefirstfurnaceinliquidform,atthestartand / orduringtheprocess, preferablyatatemperaturerangingfrom500°Cto650°C. Duringoperationofthefirstfurnace,bothcomponentsarepreferablyprovided30 tosaidfirstfurnaceinacontinuousmode. 2024 / 5970 BE2024 / 5970 13 Accordingtothemethod,saidfeedcompositionismixedinafirstfurnacewithan amountofaliquidmoltenmetalcompositionatatemperatureT1rangingfrom450°C to850°C.ItwillbeunderstoodthatthistemperatureT1ismeasurableduringatleast partoftheperiodofmixingwithinthefirstfurnace,moreinparticularbymeasuring5 thetemperatureofthemixtureofsaidfeedcompositionandsaidliquidmoltenmetal composition.Typically,saidtemperatureT1ismeasuredattheendofthemixingstep b).ItsufficesthatsaidtemperatureT1canbemeasuredasanaverageinsaidfirstliquid moltenmetalphase,formedbysaidfeedcompositionandsaidliquidmoltenmetal composition.10 Inembodimentsaccordingtotheinvention,saidfeedcompositionismixedin saidfirstfurnacewithanamountofsaidliquidmoltenmetalcompositionata temperaturewhichisatleast450°C,preferablyatleast500°C,morepreferablyat least550°C,evenmorepreferablyatleast600°C.Itisfurtherunderstoodthatsaid feedcompositionismixedinsaidfirstfurnacewithanamountofsaidliquidmolten15 metalcompositionatatemperaturewhichisatmost850°C,preferablyatmost800°C,andmostpreferablyatmost750°C. Accordingtotheinvention,saidliquidmoltenmetalcompositioncomprisesan amountofzinc,equaltoorhigherthan80.00wt.%,relativetothetotalweightofsaid20 liquidmoltenmetalcomposition.Preferably,saidliquidmoltenmetalcomposition comprisesatleast80.00wt.%,morepreferablyatleast82.00wt.%,evenmore preferablyatleast84.00wt.%,preferablyatleast86.00wt.%,morepreferablyatleast 88.00wt.%,evenmorepreferablyatleast90.00wt.%,preferablyatleast92.00wt.% andmostpreferablyatleast94.00wt.%ofzinc,withreferencetothetotalweightof25 saidliquidmoltenmetalcomposition. Inpreferredembodiments,saidliquidmoltenmetalcompositioncomprises nearlyonlyzinc,oraround100wt.%zinc,withreferencetothetotalweightofsaid liquidmoltenmetalcomposition.Insuchembodiments,saidliquidmoltenmetal compositionmayfurthercontaintraceconcentrationsofotherelements.30 2024 / 5970 BE2024 / 5970 14 Accordingtoembodiments,saidliquidmoltenmetalcompositioncomprises preferablyatmost99.50wt.%,morepreferablyatmost99.00wt.%,andmost preferablyatmost98.00wt.%ofzinc,withreferencetothetotalweightofsaidliquid moltenmetalcomposition. Inembodimentsaccordingtotheinvention,saidliquidmoltenmetal5 compositionrelatestoarecycledzinccompositionasproducedaccordingtothe methoddescribedinEP4314364B1. Inembodimentsaccordingtotheinvention,saidliquidmoltenmetal compositionfurthercomprisesotherelements,whichmayrelatetometals,metalloidsor nonmetalsandwhereinthesumofsaidotherelementsislessthan5.00wt.%,preferably10 lessthan4.00wt.%,morepreferablylessthan3.00wt.%,evenmorepreferablylessthan 2.00wt.%andmostpreferablylessthan1.00wt.%,relativetothetotalweightofthe liquidmoltenmetalcomposition. Inembodimentsaccordingtotheinvention,saidfeedcompositionismixedin15 saidfirstfurnacewithanamountofaliquidmoltenmetalcomposition,foraperiodof timewhichisatleast30minutes,preferablyatleast1hour,andmostpreferablyatleast 1.5hour.Itisfurtherunderstoodthatsaidfeedcompositionismixedinsaidfirstfurnace withanamountofaliquidmoltenmetalcomposition,foraperiodoftimewhichis preferablyatmost5hours,morepreferablyatmost4.5hours,evenmorepreferablyat20 most4hours,preferablyatmost3.5hours,morepreferablyatmost3hoursandmost preferablyatmost2.5hours.Saidperiodoftimeformixingisthereinmeasuredfromthe momentintimeofaddingthesecondcomponentofsaidfeedcompositionandsaidliquid moltenmetalcompositiontosaidfirstfurnace,totheearlierofthemomentintimeofat leastpartiallyremovingsaidfirstsupernatantdrossorinitiatingcoolingofthefirstmolten25 metalphaseunderstepc). Accordingtotheinvention,saidfeedcompositionismixedinsaidfirstfurnace withanamountofsaidliquidmoltenmetalcomposition,inthepresenceofatleastone flux,soastoformafirstliquidmoltenmetalphaseandafirstsupernatantdrosswhich30 2024 / 5970 BE2024 / 5970 15 undertheinfluenceofgravitycomesfloatingontopofsaidfirstliquidmoltenmetal phase. Accordingtotheinvention,theamountofsaidliquidmoltenmetal compositionthatismixedwithsaidfeedcompositioninsaidfirstfurnace,isselected suchthatthefirstliquidmoltenmetalphasecomprises,relativetothetotalweightof5 saidfirstliquidmoltenmetalphase,from10.00to40.00wt.%ofaluminium. Inembodimentsaccordingtotheinvention,theamountofsaidliquidmolten metalcompositionthatismixedwithsaidfeedcompositioninsaidfirstfurnace,is selectedsuchthatthefirstliquidmoltenmetalphasecomprises,relativetothetotal weightofsaidfirstliquidmoltenmetalphase,from20.00to40.00wt.%,preferably10 from20.00to35.00wt.%,andmostpreferablyfrom25.00to35.00wt.%,of aluminium. Accordingtotheinvention,saidfeedcompositionismixedinafirstfurnacewith anamountofaliquidmoltenmetalcompositioninthepresenceofatleastoneflux.In15 otherwords,atleastonefluxwillbeaddedtosaidmixtureofsaidfeedcompositionand saidliquidmoltenmetalcomposition,atsomepointduringmixing.Thiswilltypicallybe doneuponorrightaftermixingbothcomponents. Non-limitingexamplesofasuitablefluxforuseinstepb)ofthemethodaccording tothepresentinventionareZnS,ZnCl2,NH4Cl,(NH4)2ZnCl4,ahydrateoramixturethereof.20 Inapreferredembodimentofthemethodaccordingtothepresentinvention,the atleastonefluxisselectedfromthegroupconsistingofZnS,ZnCl2,NH4Cl,(NH4)2ZnCl4, hydratesandmixturesthereof. Withinthecontextofthepresentinvention,theterm“flux”of“metalflux” relateshereintoacompound,typicallyametalcompound,oracompositionofsuch25 compounds,thatinteractwiththeimpuritiesthatarepresentduringametalalloyor metalrefiningprocess,forthepurposeofprotectingthemoltenmetalandimprovingthe qualityofthefinalproduct. Moreinparticular,theadditionoftheatleastonefluxmayserveoneormore functions,suchasnotably(further)purifyingsaidfirstliquidmoltenmetalphaseof30 undesiredcomponentsandchemicalimpuritiesascomprisedtherein,and / orfurther 2024 / 5970 BE2024 / 5970 16 liquefyingsaidfirstsupernatantdrossinsuchawaythatpartoftheamountofthefirst liquidmoltenmetalphase,comprisingthezinc(Zn)toberecycled,trappedinthefirst supernatantdrosscannowbebroughtbackintotheunderlyingfirstliquidmoltenmetal phase. Theinventorshavefoundthataddingatleastoneflux,asdescribedherein,tothe5 mixtureofsaidfeedcompositionandsaidliquidmoltenmetalcomposition,allowsfor bettertrappingimpuritiessuchasFeinaconjunctionwithAl.Furthermore,ithasbeen foundthat,throughtheadditionofsaidflux,apartoftheamountofaliquidmoltenmetal phasewhichistrappedinasupernatantdrosscanbesuccessfullybroughtbackintothe underlyingliquidmoltenmetalphase,withoutfurthercontaminatingthisliquidmolten10 metalphasewithforinstancemetaloxidesand / orintermetalliccompoundsascomprised inthesupernatantdross. Inembodiments,saidfluxisaddedtosaidmixtureofsaidfeedcompositionand saidliquidmoltenmetalcomposition,inanamountofpreferablyatmost0.50wt.%,more preferablyatmost0.40wt.%,evenmorepreferablyatmost0.30wt.%,preferablyatmost15 0.20wt.%andmostpreferablyatmost0.10wt.%,withrespecttothetotalweightofsaid firstliquidmoltenmetalphase. Inasubsequentstepc)ofthemethodaccordingtotheinvention,saidfirstliquid moltenmetalphaseiscooledinthefirstfurnacetoatemperatureT2,whichtemperature20 T2islowerthanthetemperatureofmixingT1instepb),soastoformasecondliquid moltenmetalphaseandasecondsupernatantdross,whichundertheinfluenceofgravity comesfloatingontopofsaidsecondliquidmoltenmetalphase. Ithasthereinbeenfoundthatsaidcoolingstepc)advantageouslyresultsina furtherconcentratingofimpuritiesinasupernatantdross.25 Inembodimentsaccordingtotheinvention,saidfirstliquidmoltenmetalphaseis cooledinthefirstfurnacetosaidlowertemperature,afteratleastpartialremovalofthe firstsupernatantdross.Insuchembodiments,atleast80wt.%ofsaidfirstsupernatant dross,withrespecttotheweightofsaidfirstsupernatantdross,ispreferablyremoved beforecoolingsaidfirstliquidmoltenmetalphase.Morepreferably,atleast90wt.%of30 2024 / 5970 BE2024 / 5970 17 saidfirstsupernatantdross,withrespecttotheweightofsaidfirstsupernatantdross,is removedbeforecoolingsaidfirstliquidmoltenmetalphase. Preferably,saidfirstsupernatantdrossisremovedfromsaidfirstfurnaceby manualormechanicalskimming. Inembodimentsaccordingtotheinvention,saidtemperatureT2isfrom420°C5 to600°C,preferablyfrom420°Cto550°C,andmostpreferablyfrom420°Cto500°C. Inembodimentsaccordingtotheinvention,saidtemperatureT2isatleast420 °C,preferablyatleast430°C,andmostpreferablyatleast440°C.Itisfurther understoodthatsaidtemperatureT2ispreferablyatmost800°C,morepreferablyat most750°C,evenmorepreferablyatmost700°C,preferablyatmost650°C,more10 preferablyatmost600°C,evenmorepreferablyatmost550°C,andmostpreferablyat most500°C. Inembodimentsaccordingtotheinvention,saidtemperatureT2isatleast20 °ClowerthantemperatureT1,preferablyatleast40°C,morepreferablyatleast60°C, evenmorepreferablyatleast80°C,preferablyatleast100°C,morepreferablyatleast15 120°C,evenmorepreferablyatleast140°C,andmostpreferablyatleast160°C. ItwillbeunderstoodthatthistemperatureT2ismeasurableatleastata certainpointinthemoltenmetalphaseinthefirstfurnace.Typically,saidtemperature T2ismeasuredattheendofthecoolingstepc).Itthereinsufficesthatsaid temperatureT2canbemeasuredasanaverageinsaidsecondliquidmoltenmetal20 phase. Accordingtotheinvention,saidfirstliquidmoltenmetalphaseiscooledinthe firstfurnacesoastoformasecondliquidmoltenmetalphaseandasecond supernatantdrosswhichundertheinfluenceofgravitycomesfloatingontopofsaid secondliquidmoltenmetalphase.25 Inembodiments,saidfirstsupernatantdrossisnotremovedbeforecoolingsaid firstliquidmoltenmetalphaseaccordingtostepc).Itwillbeappreciatedbytheperson skilledintheartthatsaidfirstsupernatantdross,oranyremainingportionsthereofin casesaidfirstsupernatantdrossispartiallyand / orincompletelyremoved,would mergewithanynewlyformedsecondsupernatantdrossduringthecoolingstepc).30 Suchafusionisalsoreferredtohereinassaidsecondsupernatantdross. 2024 / 5970 BE2024 / 5970 18 Inembodimentsaccordingtotheinvention,saidfirstliquidmoltenmetalphase iscooledinthefirstfurnacetoatemperatureT2foraperiodoftimewhichisatleast30 minutes,preferablyatleast1hour,andmostpreferablyatleast1.5hour.Itisfurther understoodthatsaidfirstliquidmoltenmetalphaseiscooledinthefirstfurnacetoa temperatureT2foraperiodoftimewhichispreferablyatmost5hours,morepreferably5 atmost4.5hours,evenmorepreferablyatmost4hours,preferablyatmost3.5hours, morepreferablyatmost3hoursandmostpreferablyatmost2.5hours.Saidperiodof timeforcoolingrelatestotheperiodoftimeduringwhichanymeasuresforcoolingare activated,suchase.g.thecirculationofacoolingfluidinthewallsofsaidfirstfurnace. 10 Inasubsequentstepd)ofthemethodaccordingtotheinvention,saidsecond liquidmoltenmetalphaseistransferred,optionallyafteratleastpartialremovalofsaid secondsupernatantdross,fromsaidfirstfurnacetoasecondfurnace,soastoforma thirdliquidmoltenmetalphaseandathirdsupernatantdrosswhichunderthe influenceofgravitycomesfloatingontopofsaidthirdliquidmoltenmetalphase.15 Inembodimentsaccordingtotheinvention,saidsecondliquidmoltenmetal phaseistransferredafteratleastpartialremovalofsaidsecondsupernatantdross.In suchembodiments,atleast80wt.%ofsaidsecondsupernatantdross,withrespecttothe weightofsaidsecondsupernatantdross,ispreferablyremovedbeforetransferofsecond liquidmoltenmetalphasefromsaidfirstfurnacetoasecondfurnace.Morepreferably,20 atleast90wt.%ofsaidsecondsupernatantdross,withrespecttotheweightofsaid secondsupernatantdross,isremovedbeforetransferofsecondliquidmoltenmetal phasefromsaidfirstfurnacetoasecondfurnace. Preferably,saidsecondsupernatantdrossisremovedfromsaidfirstfurnaceby manualormechanicalskimming.25 Inembodiments,saidsecondsupernatantdrossisnotremovedbefore transferringsaidsecondliquidmoltenmetalphaseaccordingtostepd).Itwillbe appreciatedbythepersonskilledintheartthatsaidsecondsupernatantdross,orany remainingportionsthereofincasesaidsecondsupernatantdrossispartiallyand / or incompletelyremoved,wouldmergewithanynewlyformedthirdsupernatantdross30 2024 / 5970 BE2024 / 5970 19 duringthetransferringstepd).Suchafusionisalsoreferredtohereinassaidthird supernatantdross. Inembodimentsaccordingtotheinvention,saidtransferofsaidsecondliquid moltenmetalphaseisexecutedbyuseofatleastoneofthefollowing:5 -ladletransfer; -tappingviaachanneloratrough; -pumptransfer; -tilt-pourtransfer; Withinthecontextofthepresentinvention,transferbyladlerelatestothe10 transferofamoltenmetalphasefromafurnaceoroventoaladle,typicallyarefractory- linedladle,whichmoltenmetalphaseisthenfurthertransferredtoasecondfurnaceor oven.Theladlecanbestationary,possiblyhavingatiltingco,