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Comprehensive Utilization of Complex Titania Ore

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Comprehensive Utilization of Complex Titania Ore

    Comprehensive Utilization of Complex

    Titania Ore

    Availableonlineat,^,,vw.sciencedirect.com

    cienceDirect

    JOURNALOFIRONANDSTEELRESEARCH,INTERNATIONAL.2007,14(1):01

    06

    ComprehensiveUtilizationofComplexTitaniaOre

    YUANZhang-fu,PANYi-fang,ZHoUE,XUCong,LIShuqing

    (1_InstituteofProcessEngineering,ChineseAcademyofSciences,Beijing100080,China; 2.CenterofTechnology,TianjinIronandSteelCoLtd,Tianjin300301,China) Abstract:T0fullyutilizePanzhihuatitaniumresources,anewprocesswasproposed.Intheprocess,Panzhihuail

    meniteconcentratewasfirstreducedinarotaryhearthfurnace(RHF)toproduceatitanium-richmaterialandirOl1.,

    Thetitanium-richmaterialwasthenusedinanewchlorinationprocesstoproduceTiCh.Thecomparisonofdiffer

    entgroupsofexperimentalresultsorcalculationresultsshowedthattheutilizationratioofmaterialwasimproved

    byusingthetitanium-richmaterialafterpretreatmentotherthanlowleveltitanicilmenitedirectlyandthecorn

    binedfluidizedbeds(FTF)weremorelikelytoreducebedheightandreactiontimethanthesinglefluidizedbeds

    (Sin

    gleForSingleT)undertheconditionofthesamechlorinationconversionratio.Finally,theinfluenceofre

    ductiontemperatureandtheanti-agglomerationcapacityofthecombinedfluidizedbedwasanalyzed.

Keywords:ilmenite;rotaryhearthfurnace;fluidizedbed;anti-agglomeration

    Ilmenite,nominallyferrousmetatitanateorFe

    Tio3,isanimportantminera1.Duetothehighcon- tentofimpuritiesinilmenite,especiallyiron,itis necessarytorefineilmenitetoobtaintitanium-rich material[?.Overthepastfortyyears,therehas

    beenanincreasedinterestinthereductionofnatu

    rallyoccurringilmeniteaswellassyntheticilmen

    ite[.

    Ilmeniteisconsideredbymanufacturersofti

    taniumdioxideasanalternativeraw,maferialtonat: uralruffle.Severalmethodshavebeenproposedto refineilmenite[.一引,including~melting,directacid leaching,selectivechlorination,andreduction.The reductionofilmeniteisanimportantstepinthetita- niumindustrytodecreaseboththereagentconsump

    tionandtheaccumulatiOnofwastematerialinthe subsequentpigmentmakingprocess[.

    Thereareabout9.66billiontonsofvanadium- bearingtitaniferousmagnetiteinPanzhihua,China, containingmorethan20kindsofraremetals.Inthis reserve,thereisabout8.73×10tofTiO2(account

    ingfor90.54ofthenationalreserves,35.17of theintemationalreserves,andrankingfirstinthe world)[.About1.15×10tofvanadiurn-bearingti

    taniferousmagnetite(containingTi02of10.63in masspercent)areexploitedeveryyear,andthusabout 1.2×10tofTiO2areexploited.However,theca

    pacityofthetitaniaplantisinsufficient,andatpres-

ent.onlyabout2.0×10tofilmeniteconcentrate

    (Tio2of47)and1.0×10toftitania(withsul

    fateprocess)areproducedeveryyear.Theutiliza- tionratiooftitaniumintheoriginalresourcesisonly about4.9.Therefore,investigationswerecarried outtoenrichthefinetitaniumores,viaamill-run fromvanadium-bearingtitaniferousmagnetite,to preparetitaniumdioxideusingachlorinationandox

    idationprocess.

    1Experimental

    1.1ReductionofPanzhihuaiimeniteconcentrate ThePanzhihuailmeniteconcentratewasinvestiga

    ted.Itschemicalcomposition(masspercent,)is: Ti0247.09,?Fe30.86,Feo34.64,Fe2Os5.52,

    MgO5.89,CaO1.57,MnO0.65,Al2031.70,Si02 3.53,S0.102,andV2O50.095.Thecarbonaceous reducingagent,usedfordeoxidizingferriferousox

    ideandfurtherpreparingformagneticallyseparated FoundationIle;ItemSponsoredbyNationalNaturalScienceFoundationofChina(20306030

    )

    Biography:.

    Y.U~NZhang-fu(19,63

    ),Male,Doctor,ProfessoriE-nmil:yuanzhf@home.ipe.ac.on;RevisedDate:September

    2,2005

    S

    ,

    ,

    一一?

    郴?

    JournalofIronandSteelResearch.InternationalVo1.14 processoracidextractionorelsemethod,hasa composition(masspercent,)ofcarbon91.3,hy- drogen1.65,volatile5.71,andash3.13.Aftersic

    ving,theilmeniteconcentratewithasizerangefrom 71ttmto150ttm,whichaccountedformorethan 70oftheoriginalmaterial,wasusedintheexperi- ments.Thecarbonaceousreducingagentwascrushed andsievedtoproduceparticlesofsimilarsize. WeighedamountsofthePanzhihuailmenite

    concentrateandcarbonaceousreducingagentwere thoroughlymixedbystirringforover60min,and thenacertainamountofadhesivewasaddedtothe mixture.Afterthat,themixturewaspressedina dieof8mmindiameterunderapressureof15MPa toproducecylindricalpelletsofabout5ginweight and10mminheight.Inallexperiments,theratio ofcarbontooxygenofconcentratewas2inthecy

    lindricalpellets.Thiscorrespondstothestoichio

    metriccarbonrequirementifalltheoxygenintheil

    meniteconcentratesamplesformscarbonmonoxide. Thereductionexperimentsoftheilmeniteconcentrate werecarriedoutinanelectricfurnacewithcarborundum barsasheaters.Themaincomponentsofthissystem areahorizontalcarborundumfurnace,atemperature controller,andarecrystallizedaluminatube. Severaltechniqueswereusedforthecharacter

    izationofinitialandreducedsamples.Thephase characteristicsoftheilmeniteconcentratebeforeand afterreductionwereobtainedusingx-raydiffraction

    withacobaltKasource(XRD)(D/MAX,Rigaku, Japan).Themicroscopicmorphologieswereob- servedusingahlgh-resolutionscanningelectronml

    croscope(SEM)(JSM-35CF,JEOL,Japan). 1.2ChlorinationofhigIItitaniumslag Twokindsofhightitaniumslagwithaparticle

    165mwereused,andthe sizerangewithin75

    correspondingchemicalcompositions(masspercent, )areshowninTable1.Thepetrolcokeforpart ofheatsupplyforthechlorinationreactionusingox

    ygenhadachemicalcompositionofcarbon95.45, volatile3.89,ash0.66,andH2O0.2,andhada particlesizerangewithin0.5——0.85mlTUPriortothe

    reaction,sufficientpremixingshouldbedonetoobtain amassratiooftheslagtopetrolcokeof100:30or 100:40.Purechlorinewasusedtochlorinatethe premixedsolidmateria1.Inthechlorinationprocess, chloridessuchasMnCI2andFeCI2werealsogenera

    ted,whichweretransformedtoliquid;CaC12and MgClzwerethekeyelementsforagglomerationand wereexamined.

    TheflowprocessdiagramisshowninFig.1.A Table1Chemicalcompositionofhightitaniumslag N2

    Ch

    …….I'.

    1Vacuumvalve;2

    Fl0winstrument;3--Preheater;4--Reactor;5--ScrewfeederI6--Electricfurnacel

    7--Thermocouple;8--Cycloneseparator;9

Solidtank;10--Solidsample;11--CondenserI12LiquidtankI

    13--Liquidsample;l4GassampleIl5

    AIkaIitank;16--Bag-typedustcollectorl17--Crossovervalve

    rig.1Schemticdiaofchlorinationexperiment

    No.1ComprehensiveUtilizationofComplexTitaniaOre quartzreactorwasemployed,inwhichthedimen

    sions(height×innerdiameter)offirstfastfluidized bed,turbulentfluidizedbed,andsecondfastfluid- izedbedwere710mm×22mm,636mm×59mm,

    and320mm×22mm.respectively.Thescrewfeed

    erwasconnectedtothebottomofthefirstfast-flu- idizedbedthroughaninclinedtubeandthepure chlorinepreheatedbythepreheaterwasalsointro- ducedatthebottom.Thereactorwassurroundedby anelectricfurnacetoensurethattherequiredreac

    tiontemperaturewasaccuratelycontrolledusing thermocouplesandatemperaturecontrollingsys- tem.Inthecycloneseparator,thesolidsentrained bygaswerecollected.Theirchemicalcomponents andcompositionswereanalyzedbytitrationand plasmaemissionspectrometer(ICP.-AES)respec- tively.Thegaseswerethentransferredfromthecy

    cloneseparatorintothecondenserandcooledto roomtemperaturetocollecttheliquidTiCl.Final

    ly,theof~gasesweresampled,analyzedandintro

    ducedintothealkalitanktoremovetheresidual chlorine.Thecontentoftheresidualchlorineinthe gassamplewasdeterminedbyabsorptioninthe NaOHsolution,andthecontentofothermatterwas

    determinedbygaschromatograph(Shimadzu,GC_ 14B).Fromthecompositionofthesolid,gasand liquidsamples,theconversionofthematerialscan beobtained.

    2ResultsandDiscussion

    2.1Reductionofilmeniteconcentrate

    2.1.1Phasechangeafterreduction

    Thephasesofilmenitebeforeandafterreduction wereanalyzedusingX-raydiffraction(XRD).TheXRD resultoftheilmeniteshowedthatthemainphaseisFe

    Ti03.Rd.E83showedthatthephasesafterreduc

    tionat9001100?wereiron,ilmenite,rutile,

    reducedrutiles,andcarbon.Inthepresentstudy, the8arflephaseswereobservedat1200?.However.

    noilmenitewasobservedat1300?and1400?.In

    stead,aTi3O5phasewasfoundtogetherwithiron, reducedruffle,andcarbon.

    TheXRDresultsalsoshowedthatat9001400

    ?,theilmenitewasreducedtoformironandaJ1M3 phase.At1300?.itwasfoundthatneitherilmen

    itenorrutilewaspresentinthereducedproductaf

    terreductionfor1hc.Withtheincreaseintime.

    theintensityofironincreased.Thex_raydiffraction imageindicatedthepresenceofapseudobrookite structurewithad-spacingcharacteristicofanM3O5 solidsolution(M=Fe,Ti,Mg,etc).Theferrous pseudobrookiteisstableat1300?becauseofthe

    presenceofmagnesiumandmanganeseimpurities. 2.1.2MorphologyofreducedPanzhihuailmenite

TheSEMimagesofthecylindricalilmenitepel

    letobtainedatdifferenttemperaturesafterreduction for2hareshowninFig.2.Ingeneral,thereare threedifferentmorphologicalregionsinthereacted cylindricalpellets.Thewhiteregionindicatesiron, grayindicatesM3O5,andblackindicatescarbon. Themorphologyoftheironproduceddependson manyfactors,andthemostimportantoneisthere

    ductiontemperature.Atahightemperature,alarge numberofironnucleatedandgrewsimultaneouslyto accommodatethehighrateofreduction.Thehigh ratesofreductiondonotfavorthecoarseningofthe iron.ItcanbeseenfromFig.2thatbelow1200?,

    ilmeniteisfirstreducedtoformanintimatemixture ofironandM3O5,andabove1300?,theironis

    muchfinerandisuniformlydistributedintheparti

    cles.

    2.2Chlorinationoftitanium-richmaterials 2.2.1Numericalmodelofcombinedfluidizedbed MoosonKwaukhasdevelopedmanycalculation modelsforfluidizedbeds,especiallyformultistage bedsc.Accordingtohisanalysis.thecombinedflu

    idizedbedsshowsuperiorperformancecompared withsimplefluidizedbeds.Withthesameconver

    sionratio,theformerneedsalowerbedheightora shorterreactiontime.Basedonthiscalculationre

    suit,anewtypeofcombinedfluidizedbedsforthe chlorinationoftitaniumslagwasdesigned.Fig.3 showsthetwofastbeds(denotedas1stF,2ndF) andoneturbulentbed(denotedas1stT).

    AssumingthatthechlorinationreactionofTio2isa first-orderreactionwithrespecttotheTi02concentra- tionandthepartialpressureofCI2,/dO一一kcpand

    dc/dO=kcPfortheturbulentbedandthefast

    bed,respectively,wherec,0,k,andPrepresent theconcentration,reactiontime,reactionconstant, andthepartialpressureofC12,respectively,andthe subscriptdenotesthepositionattheexitofthe correspondingbed.Withc0representingtheinitial concentrationofTiO2intheilmeniteconcentrateand P0representingtheinitialpartialpressureofC12, theEqn.(1)andEqn.(2)forfastbedandturbulent bed,respectively,basedonthemassequilibrium equationsof2u,(coc)/M=E(Pop)/(RT)and

    2u,(f0)/M=ug(p0)/(RT)forfastbedand

    JournalofIronandSteelResearch,InternationalVo1.14 (a)900?;(b)1000?;(c)1100?;(d)1200?;(e)1300?;(f)1400?

    Fig.2SEMofPanzhihuailmeniteconcentrateaftercarbothermalreduction

    2ndF

    UDcz

    ffUg,

    I1stT

    l

    Uf,C1

    ffPt

    1stF

    Fig.3IllustrationofdifferentCxincombinedfluidizedbed turbulentbed,respectively,arededucedasfollows.

O=kp.ln1a(1C/)

    C

    @一一

    (1)

    (2)

    hera一一/;isrelatic/co0vereacti.n一一?vereacnon time(dimensionlessvariant);Ufisfeedingrateofil

    meniteconcentrate;Ugisgasvelocity;Risgascon

    stant;TiSreactiontemperature;andMiSmolar

    massofTiO,.

    Similarly.anumexicalmodelforthenewseries

    beds,and@(1,2,3correspondingto1stF,1st Tand2ndF,respectively)canbecalculatedasfol

    lOWS:

    @.=kp..ln

    02kpo02

    1一口(1C1)

    I}

    C1——C2

    Cl

    C2E1--a(1C)]

    (3)

    (4)

    @.=kpo031?

    n

    器?

    If/gissetto1.32l/m.,withCo=68,T

    1173K,andP02.205×10Pa,retainsthevalue 0f0.993accordingtothecalculationbasedonthe

    givenexperimentalparameters.Withtheseparame-

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