Combined sulphationchlorination roasting of oxides.docx
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Combined sulphationchlorination roasting of oxides.docx
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Combinedsulphationchlorinationroastingofoxides
Combinedsulphation-chlorinationroastingofoxides
Abstract:
ThefeasibilityofextractingmetallicvaluesintheformofchloridesfromlowgrademultimetallicleanoresusingSO2,O2andNaClasreactantsisanalysedfromathermodynamicpointofview.Ganguematerialssuchassilicaandaluminadonotreact.Theoxidesofmostothermetalsreacttoformchlorides.Thevolatilechloridescanbecondensed.Thechloridespresentinthecondensedstatecanbeleached.Anefficientseparationofthemetallicvaluesfromthegangueispossibleusingacombinedsulphation-chlorinationroastingprocess.Useofsodiumchlorideasachlorinationagentisattractivebecauseofitsnon-toxicnature.
Keywords
∙Beneficiation;
∙multimetallicdeposit;
∙lowgradeoxideore;
∙NaCl;
∙chlorination;
∙sulphation;
∙recovery;
∙extraction;
∙basemetals
RajmohanN,JacobKT.Combinedsulphation-chlorinationroastingofoxides[J].MineralsEng,1992,5
(2):
235-243.
Alowtemperaturechlorination–volatilizationprocessforthetreatmentofchalcopyriteconcentrates
Abstract
ChlorinationoftwochalcopyriteconcentrateswithCl2+N2wasinvestigatedunderisothermalconditionsinthetemperaturerangeof20–750°Cusingboatexperiments.Theeffectsofgasflowrate,chlorinecontentofthegasmixtureandresidencetimeonthereactionratewerealsoinvestigated.Scanningelectronmicroscopy(SEM),X-raydiffraction(XRD),andchemicalanalysisareusedforthephysico-chemicalcharacterizationofthereactionproducts.
ThechlorinationofchalcopyriteconcentratesstartedatroomtemperaturegeneratingchloridesofCu,Pb,Zn,Fe,andS.Thereactionofchlorinewithsulfidesisalmostcompleteatabout300°Candtheoverallreactionisexothermic.Atthistemperature,thevaluablemetalchlorideswereconcentratedinthechlorinationresidues,whilethoseofironandsulfurwerevolatilized.
Aflowsheetisproposedfortheselectivechlorinationofchalcopyriteconcentratesatlowtemperatures.Suchflowsheetcouldbeconsideredasanattractiverouteforthesulfideconcentrates’treatmentwithoutSOxemissions.Itcouldbealsoregardedasenergysavingwithrespecttotheclassicalpyrometallurgicalroutes.
Keywords
∙Chalcopyrite;
∙Chlorination–volatilization
Thermodynamicsofsaltroastingofsulphideores
Abstract
Thermodynamicanalysisofanon-pollutingprocessfortheeffectivetreatmentofleanmultimetallicsulphideoresispresented.Thesulphideoreisroastedwithsodiumchlorideinair.Metalsulphidesareconvertedtochloridesthatcanbeseparatedfromtheunaffectedganguematerial.Atatemperatureof1100Kthechloridesarepresentbothingaseousandincondensedstates.Volatilechloridescanbeeasilyremovedandsubsequentlycondensed.Thechloridespresentinthecondensedstatecanbeleachedtoseparatethemfromthegangue.ThesulphuristrappedasNa2SO4andthusSO2emissionisminimized.Ellinghamdiagramsareusedtocomparedataforalargenumberofelements.ThemajorthermodynamicdrivingforceisprovidedbythehigherstabilityofNa2SO4relativetoNaCl.
Keywords:
ThermodynamicAnalysis;ThermodynamicProperties;SulfideOre;Pyrometallurgy;OreTreatment;Chlorination;Calcining;MetalSulfides;SodiumSulfates;SodiumChlorides;GibbsFreeEnergy;ExperimentalStudy;
Thermalanalysisofchalcopyriteroastingreactions
Abstract
Roastingofchalcopyriteandofthebinarycopperandironsulphidescovellite,chalcocite,pyrrhotiteandpyritehasbeenthesubjectofmanyinvestigations.Theadditionofsaltstosuchreactionsisofpracticalinterestbecauseitlowersthedecompositiontemperatureandleadstowater-leachablesulphatesandchlorides.
Thesaltroastingofcopperbearingsulphidesisaverycomplexprocessinvolvingnumerousreactionstepswhichhavenotbeenadequatelycharacterized.
Theaimofthepresentinvestigationswastostudythereactionmechanismofsulphideroastinginmoredetail.Thecombinationofthermo-analyticalmethods(MettlerThermosystemTA4000)andX-raydiffraction(XRD)provedtobeveryusefulforsuchstudies.MixtureswithdifferentratiosofCuFeS2(andalsoCuSandFeS1−x)andNaCl,KC1orNH4Clwereheatedinanoxidizingatmosphereeithercontinuously(heatingratesfrom0.2–10°Cmin−1)orstepwiseisothermally.Purechalcopyritestartstooxidizeatabout400°C.
Additionofalkalichloridestochalcopyritelowersthetemperaturedecompositionandoxidationquitedrastically,especiallyinthecaseofNH4ClandKCl.Astronglyexothermicreactionwithcorrespondingweightincreasehadalreadybegunatabout200°C.Slowheatingratesthroughoutthedecompositionregion(notfasterthan0.2°Cmin−1,coveredcruciblesandadditionofexcesssalt(preferably4–5molesofsaltto1moleofchalcopyrite)areimportantforthecompletenessofthereactioninmixtureswithNH4Cl.
Correspondenceto:
H.G.Wiedemann,Mettler-ToledoAG,CH-8606Greifensee/ZHSwitzerland.
Copyright©1992PublishedbyElsevierB.V.
Saltroastingofanoff-gradecopperconcentrate
Abstract
Laboratoryinvestigationshavebeenconductedtoexplorethefeasibilityofasaltroast-waterleachrouteasameansofrecoveringcopperandzincsimultaneouslyfromanoff-gradechalcopyriteconcentrate(fromSikkim)withasignificantamountofassociatedsphalerite.Detailedstudiesindicatethepossibilityofrecoveringover95%Cuand97%Znintoleachliquor(withnegligibleFeandPb)bytreatmentoftheconcentrateat350℃for3h,employing20wt%NaCl,6mmbeddepthandanairflowrateof1l/min.Mineralphaseidentificationinthesalt-roastedcalcinesbyX-raydiffraction,analysesoftheoff-gasesandreactorcondensates,anddeterminationofthechloridetosulphateratiosofleachliquorsindicatethatthechemistryofsaltroastingofthesulphideconcentrateisatrulycomplexprocess.
KineticsofsaltroastingofchalcopyriteusingKCl
Abstract
Theprocessofsaltroastingappearstobeverypromisingbecauseitlowersthereactiontemperatureandleadstowatersolublechloridesalt.ThispaperpresentsthekineticsofsaltroastingofchalcopyriteusingKClasthechlorinatingagent.Isothermalthermogravimetricstudieswerecarriedoutinthetemperaturerangeof523–773 Kunderoxygen,staticairandargonatmospheres.Itisobservedthattheweightgainismoreinthepresenceofoxygenthaninstaticair.Weightlossisobservedwhensaltroastingiscarriedoutunderaninertatmosphere.Itisdeducedthatthereactionischemicallycontrolledattemperaturesbelow600 Kbothunderstaticairandoxygenatmosphere.Athighertemperatures,theprocessisnotthermallyactivated.Theweightgaindecreaseswithincreaseintemperaturebecauseofachangeinthechemistryoftheprocess.Theroastingexperimentscarriedoutinahorizontalelectrictubefurnaceunderanoxygenatmosphereshowsthatupto96%CucanberecoveredfromthechalcopyritebysaltroastingwithKClandsubsequentwaterleaching.
Keywords
∙Kinetics;
∙Chalcopyrite;
∙Chloridisingroasting
RecyclingEAFDustbyTreatmentwithPVC
Abstract
Thisstudyinvestigatedwhetherpolyvinylchloride(PVC)canbeusedasanadditiveforthetreatmentofelectricarcfurnace(EAF)dust.ThePVCpowderwasmixedwiththedustinordertotestthesynchronoustreatmentoftworesources:
wastePVCandEAFdust.Themixturewasmadeintopelletsandsubjectedtoheatatvarioustemperatures.Theeffectsoftheheattreatmentandheatingratewereinvestigated.ThePVCemittedhydrogenchloridegasbypyrolysisandgeneratedchloridesofzinc,lead,andcadmiuminthepellets.Thesechloridescanberecoveredbyvolatilizationorleachingaftertheheattreatment.Theresidualpelletofthisprocesscontainedover45%iron,anditisexpectedthattheresidualpelletcanbeinjectedintotheelectricarcfurnace.
Keywords
∙EAFdust;
∙PVC;
∙Recycle;
∙Heattreatment;
∙Volatilization
BehaviourofmetalsundertheconditionsofroastingMSWincineratorflyashwithchlorinatingagents
Abstract
Atotalelementalanalysiswasperformedonamunicipalsolidwaste(MSW)flyashsample,beforeandafteritwastreatedat1000°C,torevealthemetaldistributionbetweenthevolatilematterandtheashresidue.MetalssuchasPb,Zn,Cd,andtoalesserdegree,Cr,MnandNi,werevolatilized.Additionofchlorinatingagentsgenerallyincreasedthevolatilityofcertainelements.MoreacidresistantcompoundswereformedintheashresidueaftertheheattreatmentusingCaCl2asachlorinatingagent.Theefficienciesofvolatilizationofthemetals,usingCl2asachlorinatingagent,weregenerallyhighercomparedwithusingCaCl2.However,CaCl2wasfoundtobeamoreselectivechlorinatingagentforvolatilizingtheheavymetalsofconcern,i.e.,Pb,Cd,ZnandCu.Theefficienciesofvolatilizationoftherecoveredmetalswereapproximatelyproportionaltotheirstandardfree-energychanges(ΔG°)forthecorrespondingchlorinationreactions.
Keywords
∙Municipalsolidwaste(MSW)flyash;
∙Roasting;
∙Chlorinatingagent;
∙Heavymetal;
∙Volatilizationefficiency
EnhancedionicconductionanddisproportionationinpureCuClathighpressure
Abstract
Theopticalandelectricalpropertiesofpurecuprouschloride(CuCl)singlecrystalshavebeenstudiedunderpressureupto12GPa.Thetransitionpressuresforthethreecrystallographicphaseshavebeendeterminedas5.1±0.1GPa(ZnS→tetragonal)and8.8±0.4GPa(tetrag.-NaCl).Duringthetransitionat5.1GPa,wherethecoordinationnumberchanges,theformationofcupricionsisobserved.Thisisinterpretedasaresultofapartial,transient,andreversibledisproportionation.IntheZnSa
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