選礦學專業(yè)英語第1頁/共62頁Magneticandelectricalseparation5.3Practiceofmagneticseparation5.2Typeofmagneticseparator5.4Electricalseparation5.1MagneticseparationChapter55.5Practiceofelectricalseparation第2頁/共62頁5.1MagneticseparationMagneticseparationisbasedonthedifferenceinmagneticpropertiesbetweentheoremineralsandusedtoseparateeithervaluablemineralsfromnon-magneticgangue,e.g.magnetitefromquartz,ormagneticcontaminantsorothervalua-blemineralsfromthenon-magneticvalues.Anexampleofthisisthetin-bearingmineralcassiterite,whichisoftenassociatedwithtracesofmagnetiteorwolfra-mitewhichcanberemovedbymagneticseparators.

第3頁/共62頁5.1MagneticseparationMagneticseparationhasbeenforalmost200yearsintheconcentrationofironores,andisstillusedextensivelytoday.Awidevarietyofdeviceshavebeenused.Sincethestartofthiscenturytherehasbeenasteadyexpansioninboththeequ-ipmentavailableandtherangeoforesforwhichmagneticseparationisapplica-ble.Theremovalofsmallamountsofironandiron-bearingmineralsfromindu-strialmineralshasbecomeanimportantapplication,ashastheconcentrationofvariousferrousandnonferrousminerals.第4頁/共62頁5.1MagneticseparationAllmaterialsareaffectedinsomewaywhenplacedinamagneticfield,althou-ghwithmostsubstancestheeffectistooslighttobedetected.Materialscanbec-lassifiedintotwobroadgroups,accordingtowhethertheyareattractedorrepe-lledbyamagnet:diamagneticswhicharerepelledbyamagnetandcannotbeconcentratedmagnetically,paramagneticswhichareattractedbyamagnet.第5頁/共62頁5.1Magneticseparation

Ferromagnetismcanberegardedasaspecialcaseofparamagnetism,involvingveryhighforces.Ferromagneticmaterialshaveveryhighsusceptibilitytomagn-eticforcesandretainsomemagnetismwhenremovedfromthefield(remanenc-e).Theycanbeconcentratedinlow-intensitymagneticseparatorsandtheprinc-ipalferromagneticmineralseparatedismagnetite(Fe3O4),althoughhematite(Fe2O3)andsiderite(FeCO3)canberoastedtoproducemagnetiteandhencegivegoodseparation.Theremovalof"tramp"ironfromorescanalsoberegardedasaformoflow-intensitymagnegticseparation.第6頁/共62頁5.1MagneticseparationTheunitofmeasurementofmagneticfluxdensityormagneticinduction(B)(thenumberoflinesofforcepassingthroughaunitareaofmaterial)isthetesla(T).Themagnetisingforcewhichinducesthelinesofforcethroughamaterialiscalledthefieldintensity(H),andbyconventionhastheunitsamperepermetre(1Am-1=4π×10-7T).Theintensityofmagnetizationorthemagnetization(MA/m)ofamaterialrelatestothemagnetizationinducedinthematerial,and:whereμ0isthemagneticpermeabilityofmediuminvacuum,4π×10-7Tm/A第7頁/共62頁5.1MagneticseparationMagneticsusceptibility(S)istheratiooftheintensityofmagnetizationproducedinthematerialtothemag-neticfieldwhichproducesthemagnetization.Forpara-magneticmaterials,Sisasmallpositiveconstant,andisanegativeconstantfordiamagneticmaterials.Themagneticsusceptibilityofaferromagneticmaterialisdependentonthemagneticfield,decreasingwithfieldstrengthasthematerialbecomessaturated.第8頁/共62頁5.1MagneticseparationThecapacityofamagnettoliftaparticularmineralisdependentnotonlyonthevalueofthefieldintensity,butalsoonthefieldgradient,i.e.therateatwhichthefieldintensityincreasestowardsthemagnetsurface.Becauseparamagneticmine-ralshavehighermagneticpermeabilitiesthanthesurroundingmedia,usuallyairorwater,theyconcentratethelinesofforceofanexternalmagneticfield.Thehi-gherthemagneticsusceptibility,thehigheristhefielddensityintheparticleandthegreateristheattractionupthefieldgradienttowardsincreasingfieldstrength.Diamagneticmineralshavelowermagneticsusceptibilitythantheirsurroundi-ngmediumandhenceexpelthelinesofforceoftheexternalfield.Thiscausesth-eirexpulsioninthedirectiondownthegradientofthefieldtowardsthedecreasingfieldstrength.Thisnegativediamagneticeffectisusuallyordersofmagnitudesmallerthanthepositiveparamagneticattraction.第9頁/共62頁5.1MagneticseparationItcanbeshownthatThusinordertogenerateagivenliftingforce,thereareaninfinitenumberofcombinationsoffieldandgradientwhichwillgivethesameeffect.Productionofahighfieldgradientaswellashighintensityisthereforeanimportantaspectofseparatordesign.第10頁/共62頁5.1MagneticseparationTheforcesinmagneticseparatorsthatcompetewithmagneticforcesandactonallparticlesaregravity,hydrodynamicdrag,frictionandinertia.Ifthesepa-rationisoccurringatthesurfaceofrotatingdrum,thecentrifugalforcemayalsobeafactor.Onemaycallallofthenthecompetingforce.Itiswhenthefo-llowingrela-tionshipexiststheseparationofstronglymagneticmineralparticlesfromweaklymagneticmineralparticlescantakeplacewhereF1magisthemagneticforceonstronglymagneticmineralparticles,F2magisthemagneticforceonweaklymagneticmineralparticles,Fcompisthetotalcompetingforces.第11頁/共62頁Magneticandelectricalseparation5.3Practiceofmagneticseparation5.2Typeofmagneticseparator5.4Electricalseparation5.1MagneticseparationChapter55.5Practiceofelectricalseparation第12頁/共62頁5.2Typeofmagneticseparator

Certainelementsofdesignareincorporatedinallmagneticseparators,whethertheyareloworhighintensity,wetordry.Theprimerequirement,ashasalreadybeenmentioned,istheprovisionofahigh-intensityfie1dinwhichthereisasteepfieldstrengthgradient.Inafieldofuniformflux,suchasinFigure(a),magneticparticleswillorientthemselves,butwillnotmovealongthelinesofflux.Themoststraightforwardmethodforproducingaco-nvergingfieldisbyprovidingaV-shapedpoleaboveaflatpole,asinFigure(b).Thetape-ringoftheupperpoleconcentratesthemagneticfluxintoaverysmallareagivinghighin-tensity.Thelowerflatpolehasthesametotalmagneticfluxdistributedoveralargerarea.Thusthereisasteepfieldgradientacrossthegapbyvirtueofthedifferentintensitylevels.第13頁/共62頁5.2TypeofmagneticseparatorAnothermethodofproducingahighfieldgradientisbyusingapolewhichisconstructedofalternatemagneticandnon-magneticlaminations.Provisionmustbeincorporatedintheseparatorforregulatingtheintensityofthemagneticfieldsoastodealwithvarioustypesofmaterial.Thisiseasilyachie-vedinelectromagneticseparatorsbyvaryingthecurrent,whilewithpermanentmagnetstheinterpoledistancecanbevaried.第14頁/共62頁5.2TypeofmagneticseparatorTheintroductionintoamagneticfieldofparticleswhicharehighlysusceptibleconcentratesthelinesofforcesothattheypassthroughthem.Sincethelinesofforceconvergetotheparticles,ahighfieldgradientisprodu-ced,whichcausestheparticlesthemselvestobehaveasmagnets,thusattractingeachother.Flocculation,oragglomeration,oftheparticlescanoccuriftheyaresmallandhighlysusceptibleandifthefieldisintense.Thishasgreatimportanceasthesemagnetic"flocs"canentraingangueandcanbridgethegapsbetweenmagneticpoles,reducingtheefficiencyofseparation.第15頁/共62頁5.2TypeofmagneticseparatorMagneticseparatorscanbec1assifiedintolow-andhigh-intensitymachines,whichmaybefurtherclassifiedintodry-feedandwet-feedseparators.磁選機分類標準分類承載介質(zhì)不同干式、濕式磁選機磁場強度的高低弱磁場磁選機、強磁場磁選機礦粒在磁場中的行為有磁翻轉(zhuǎn)作用、無磁翻轉(zhuǎn)作用磁選機槽體結(jié)構(gòu)形式順流型、逆流型、半逆流型磁選機排出磁性產(chǎn)品的結(jié)構(gòu)特征圓筒式、圓錐式、帶式、輥式、盤式和環(huán)式磁場類型恒定磁場磁選機、旋轉(zhuǎn)磁場磁選機、交變磁場磁選機、脈動磁場磁選機產(chǎn)生磁場的方法永磁型、電磁型、超導型磁選機等第16頁/共62頁5.2Typeofmagneticseparator

Low-intensitymagneticseparator

(弱磁場磁選機）

Low-intensityseparatorsareusedtotreatferromagneticmaterialsandsomehighlyparamagneticminerals.Drylow-intensitymagneticseparationisconfinedmainlytotheconcentrationofcoarsesandswhicharestronglymagnetic,theprocessbeingknownascobbing,andoftenbeingcarriedoutindrumseparators.Belowthe0.5cmsizerange,dryseparationtendstobereplacedbywetmethods,whichproducemuchlessdustlossandusuallyacleanerproduct.Low-intensitywetseparationisnowwidelyusedforpurifyingthemagneticmediuminthedensemediumseparationprocess,aswellasfortheconcentrationofferromagneticsands.第17頁/共62頁5.2Typeofmagneticseparator

Low-intensitymagneticseparator

(弱磁場磁選機）

DrumseparatorsarethemostcommonmachinesincurrentuseforcleaningthemediuminDMScircuitsandarewidelyusedforconcentratingfinelygroundironore.Theyareclassifiedintoconcurrenttype(Fig(a)),counter-rotationtype(Fig(b))andcounter-currenttype(Fig(c))machines.Fig(a)concurrenttype第18頁/共62頁5.2Typeofmagneticseparator

Low-intensitymagneticseparator

(弱磁場磁選機）

Concurrentdrumseparatorsconsistessentiallyofarotatingnon-magneticdr-um(Figure(a))containingthreetosixstationarymagnetsofalternatingpolarity.Althoughinitiallydrumseparatorsemployedelectromagnets,permanentmagnetsareusedinmoderndevices,utilizingceramicorrareearthmagneticalloys,whichretaintheirintensityforanindefiniteperiod.Separationisbythe"pick-up"principle.Magneticparticlesareliftedbythemagnetsandpinnedtothedrumandareconveyedoutofthefield,leavingthegangueinthetailingscompartment.Waterisintroducedintothemachinetoprovideacurrentwhichkeepsthepulpinsuspension.Fieldinten-sitiesofupto0.7Tatthepolesurfacescanbeobtainedinthistypeofseparator.第19頁/共62頁5.2Typeofmagneticseparator

Low-intensitymagneticseparator

(弱磁場磁選機）

Concurrentdrumseparators,wherebytheconcentrateiscarriedforwardbythedrumandpassesthroughagap,whereitiscompressedanddewateredbeforeleavingtheseparator.Thisdesignismosteffectiveforproducinganextremelycleanmagneticconcentratefromrelativelycoarsematerialsandiswidelyusedindensemediumrecoverysystems.第20頁/共62頁5.2Typeofmagneticseparator

Low-intensitymagneticseparator

(弱磁場磁選機）

TheseparatorshowninFigure(b)isofthecounter-rotationtype,wherethefeedflowsintheoppositedirectiontotherotation.Thistypeisusedinroughingoper-ations,whereoccasionalsurgesinfeedmustbehandled,wheremagneticmateriallossesaretobeheldtoaminimum,whileanextremelycleanconcentrateisnotrequired,andwhenhighsolidsloadingisencountered.Fig(b)counter-rotationtype第21頁/共62頁5.2Typeofmagneticseparator

Low-intensitymagneticseparator

(弱磁場磁選機）

Figure(c)showsacounter-currentseparator,wherethetailingsareforcedtotravelintheoppositedirectiontothedrumrotationandaredischargedintothetailingschute.Thistypeofseparatorisdesignedforfinishingoperationsonrelativelyfinematerial,ofparticlesizelessthanabout250μm.Fig(c)counter-currenttype第22頁/共62頁5.2Typeofmagneticseparator

Low-intensitymagneticseparator

(弱磁場磁選機）

Drumseparatorsarewidelyusedtotreatlowgradetaconiteores,whichcontain40-50%Fe,mainlyasmagnetite,butinsomeareaswithhematite,finelydissemi-natedinbandsinhardsiliceousrocks.Veryfinegrindingisnecessarytofreetheironmineralsthatproduceaconcentratethatrequirespelletisingbeforebeingfedtotheblastfurnaces.Inatypicalflowsheettheoreisgroundprogressivelyfiner,theprimarygrindusuallybeingundertakenautogenously,orbyrodmilling,followedbymagneticseparationindrumseparators.ThemagneticconcentrateisregroundandagainTreatedindrumseparators.Thisconcentratemaybefurtherreground,followedbyathirdstageofmagneticseparation.Thetailingsfromeachstageofmagneticseparationareeitherrejectedor,insomecases,treatedbyspiralorconeconcent-ratorstorecoverhematite.第23頁/共62頁5.2Typeofmagneticseparator

Low-intensitymagneticseparator

(弱磁場磁選機）

Thecross-beltseparatoranddiscseparatorsoncewidelyusedinthemineralsan-dsindustry,particularlyforrecoveringilmenitefromheavymineralconcentrates,arenowconsideredobsolete.Theyarebeingreplacedwithrareearthrollmagne-ticseparatorsandrareearthdrummagneticseparators.Cross-beltseparator第24頁/共62頁5.2Typeofmagneticseparator

Low-intensitymagneticseparator

(弱磁場磁選機）

Rareearthrollseparatorsusealternatemagneticandnon-magneticlaminationsasshowninFigure.Feediscarriedontothemagneticrollbymeansofathinbelt,hencethereisnobouncingorscatteringofparticlesastheyenterthemagneticzone,andtheyallenterthemagneticzonewiththesamehorizontalvelocity.Thesefactorscontributetoachievingasharpseparation.Rollspeedcanbeadjustedoverawiderange,allowingtheproductqualitytobe"dialledin".Rareearthdrumseparator第25頁/共62頁5.2Typeofmagneticseparator

High-intensitymagneticseparator

(強磁場磁選機）

Veryweaklyparamagneticmineralscanonlybeeffectivelyremovedfromanorefeedifhighintensityfieldsof2Tandmorecanbeproduced.Thehigh-intensityseparatorsproducehigh-intensitymagneticfieldsbymeansofconventionalmagneticcircuits.Anelectromagneticcoilprovidesthemagneto-motiveforceandthemagneticfluxiscarriedthroughironratherlikecopper-conductingelectricity.Untilthe1960shigh-intensityseparationwasconfinedsolelytodryore,havingbeenusedcommerciallysinceabout1908.第26頁/共62頁5.2Typeofmagneticseparator

High-intensitymagneticseparator

(強磁場磁選機）

Inducedrollmagneticseparators,IRMs,arewidelyusedtotreatbeachsands,wolframite,tinores,glasssands,andphosphaterock.Theyhavealsobeenusedtotreatfeeblymagneticironores,principallyinEurope.第27頁/共62頁5.2Typeofmagneticseparator

High-intensitymagneticseparator

(強磁場磁選機）

Theroll,ontowhichtheoreisfed,iscomposedofphosphatedsteellaminatescompressedtogetheronanon-magneticstainlesssteelshaft.Byusingtwosizesoflamination,differingslightlyinouterdiameter,therollisgivenaserratedprofilewhichpromotesthehighfieldintensityandgradientrequired.Fieldstrengthsofupto2.2Tareattainableinthegapbetweenfeedpoleandroll.Nonmagneticpa-rticlesarethrownofftherollintothetailingscompartment,whereasmagneticsaregripped,carriedoutoftheinfluenceofthefieldanddepositedintothemagnet-icscompartment.Thegapbetweenthefeedpoleandrotorisadjustableandisus-uallydecreasedfrompoletopoletotakeoffsuccessivelymoreweaklymagneticproducts.第28頁/共62頁5.2Typeofmagneticseparator

High-intensitymagneticseparator

(強磁場磁選機）

Dryhigh-intensityseparationislargelylimitedtoorescontaininglittle,ifany,materialfinerthanabout75μm.Theeffectivenessofseparationonsuchfinemat-erialisseverelyreducedbytheeffectsofaircurrents,particle-particleadhesion,andparticle-rotoradhesion.Withoutdoubtthegreatestadvanceinthefieldofmagneticseparationwasthedevelopmentofcontinuouswethigh-intensitymagneticseparators,WHIMSmac-hines.Thesereducetheminimumparticlesizeforefficientseparationallowingo-restobeconcentratedmagneticallythatcannotbeconcentratedeffectivelybydryhigh-intensitymethods,becauseofthefinegrindingnecessarytoensurecompl-eteliberationofthemagneticfraction.Insomeflowsheets,expensivedryingoper-ationscanbeeliminatedbyusingawetconcentrationsystem.第29頁/共62頁5.2Typeofmagneticseparator

High-intensitymagneticseparator

(強磁場磁選機）

Perhapsthemostwell-knownWHIMSmachineistheJonesseparator,thedesi-gnprincipleofwhichisutilizedinmanyothertypesofwetseparatorusedtoday.Themachineconsistsofastrongmainframemadeofstructuralsteel.Themag-netyokesareweldedtothisframe,withtheelectromagneticcoilsenclosedinair-cooledcases.Theactualseparationtakesplaceintheplateboxeswhichareontheperipheryoftheoneortworotorsattachedtothecentralrollershaft.Thefeed,whichisthoroughlymixedslurry,flowsthroughtheseparatorviafittedpipesandlaundersintotheplateboxes,whicharegroovedtoconcentratethemagneticfi-eldatthetipoftheridges.Feedingiscontinuousduetotherotationoftheplateboxesontherotorsandthefeedpointsareattheleadingedgesofthemagneticfie-lds.Eachrotorhastwosymmetricallydisposedfeedpoints.第30頁/共62頁5.2Typeofmagneticseparator

High-intensitymagneticseparator

(強磁場磁選機）

OperatingprincipleoftheJoneshigh-intensitywetmagneticseparatorincross-section(a)planand(b)viewPlanofJonesplateboxshowinggroovedplatesandspacerbars第31頁/共62頁5.2Typeofmagneticseparator

High-intensitymagneticseparator

(強磁場磁選機）

Thefeeblymagneticparticlesareheldbytheplates,whereastheremainingnon-magneticslurrypassesstraightthroughtheplateboxesandiscollectedinalaun-der.Beforeleavingthefieldanyentrainednon-magneticsarewashedoutbylow-pressurewaterandarecollectedasamiddlingsproduct.Whentheplateboxesreachapointmidwaybetweenthetwomagneticpoles,wherethemagneticfieldisessentiallyzero,themagneticparticlesarewashedoutwithhighpressurescourwaterspraysoperatingatupto5bar.Fieldintensitiesofover2Tcanbeproducedinthesemachines.Theproductionofa1.5Tfieldrequiresanelectricpowerconsumptioninthecoilsof16kWperpole.Ofthe4tofwaterusedwitheverytonneofsolids,approximately90%isre-cycled.第32頁/共62頁5.2Typeofmagneticseparator

High-intensitymagneticseparator

(強磁場磁選機）

Wethigh-intensitymagneticseparationhasitsgreatestuseintheconcentrationoflow-gradeironorescontaininghematite,wheretheyfrequentlyreplaceflotati-onmethods.JonesseparatortreatingBrazilianhematiteore第33頁/共62頁5.2Typeofmagneticseparator

High-intensitymagneticseparator

(強磁場磁選機）

Inadditiontotheirlarge-scaleapplicationfortherecoveryofhematite,wethigh-intensityseparatorsarenowinoperationforawiderangeofduties,includingremovalofmagneticimpuritiesfromcassiteriteconcentrates,removaloffinemag-neticfromasbestos,removalofmagneticimpuritiesfromscheeliteconcentrates,purificationoftalc,therecoveryofwolframiteandnon-sulphidemolybdenum-bearingmineralsfromflotationtailings,andthetreatmentofheavymineralbeachsands.TheyhavealsobeensuccessfullyusedfortherecoveryofgoldanduraniumfromcyanidationresiduesinSouthAfrica.第34頁/共62頁5.2Typeofmagneticseparator

High-gradientmagneticseparator

(高梯度磁選機）

Theworkingfieldoccursinair-gapsinthemagneticcircuit,thedisadvantagebeingthatthevolumeofironrequiredismanytimesgreaterthanthegapvolumewhereseparationtakesplace.ThesteelplatesinaJonesseparator,forexample,occupyupto60%oftheprocessvolume.Thushigh-intensitymagneticseparatorsusingconventionalironcircuitstendtobeverymassiveandheavyinrelationtotheircapacity.Alargeseparatormaycontainover200tofirontocarrytheflux,hencecapitalandinstallationcostsareextremelyhigh.Asironsaturatesataround2-2.5T,conventionalironcircuitsareoflittlevalueforgeneratingfieldsaboveabout2T.SuchfieldscanonlybegeneratedbytheuseofhighH-fieldsproducedinsolenoids,buttheenergyconsumptionisextremelyhighandthereareproblemsincoolingthesolenoid.第35頁/共62頁5.2Typeofmagneticseparator

High-gradientmagneticseparator

(高梯度磁選機）

Analternativeistoincreasethemagneticforcebyincre-asingthevalueofthemagneticfieldgradient.Insteadofusingonelargeconvergentfieldinthegapofamagneticcircuit,theuniformfieldofasolenoidisused.Thecore,orworkingvolume,isfilledwithamatrixofsecondarypoles,suchasballbearings,orwirewool,thelatterfillingonlyabout10%oftheworkingvolume.Eachsecondarypole,duetoitshighpermeability,canproduceamaximumfieldstrengthoftheorderof2T,butmoreimpo-rtantly,eachpoleproduces,initsimmediatevicinity,highfieldgradientsofupto14Tmm-1.Thusamultitudeofhighgradientsacrossnumeroussmallgaps,centredaroundeachofthesecondarypoles,isachieved.High-gradientmagneticseparator第36頁/共62頁5.2Typeofmagneticseparator

High-gradientmagneticseparator

(高梯度磁選機）

Aninherentdisadvantageofhighgradientseparatorsisthatanincreaseinfieldgradientnecessarilyreducestheworkinggapbetweensecondarypoles,themagn-eticforcehavingonlyashortreach,usuallynotmorethan1mm.Itisthereforenecessarytousegapsofonlyabout2mmbetweenpoles,suchthatthematrixsepa-ratorsarebestsuitedtothetreatmentofveryfineparticles.Theyareusedmainlyinthekaolinindustryforremovingmicron-sizedparticleswhichcontainiron.Se-verallargeseparators,withtheferromagneticmatrixcontainedinbasketsappro-ximately2mindiameterareincommercialuseintheUnitedStatesandinCorn-wall,England.Theyoperatewithfieldsof2T,andhavecapacitiesrangingbetw-een10and80th-1dependingonthefinalclayqualitydesired.第37頁/共62頁5.2Typeofmagneticseparator

High-gradientmagneticseparator

(高梯度磁選機）

SalaHGMSSlonVPHGMS第38頁/共62頁5.2Typeofmagneticseparator

Superconductingmagneticseparator

(超導磁選機）

Fieldstrengthsinexcessof2Tcanonlybegeneratedeconomicallybytheuseofsuperconductingmagnets.Certainalloyshavethepropertyofpresentingnoresistancetoelectriccurrentsatextremelylowtemperatures.Anexampleisniobium-titaniumat4.2K,thete-mperatureofliquidhelium.Onceacurrentcommencestoflowthroughacoilm-adefromsuchasuperconductingmaterial,itwillcontinuetoflowwithoutbeingconnectedtoapowersource,andthecoilwillbecome,ineffect,apermanentma-gnet.Superconductingmagnetscanproduceextremelyintenseanduniformmag-neticfields,ofupto15T.第39頁/共62頁5.2Typeofmagneticseparator

Superconductingmagneticseparator

(超導磁選機）

The5Tmachineisanassemblyofconcentriccomponents.Aremovableprocessingcanisterisinstalledinaprocessingchamberlocatedatthecentreoftheassembly.Thisissurroundedbyadouble-walled,vacuuminsulatedcontainerthataccommodatesthesuperconductivemagnet'sniobium/titanium-tantalumwinding,andtheliquidheliumcoolant.Athermalshield,cooledwithliquidnitrogento77K,limitsradiationintothecryostat.Inoperation,thesupplyofslurryisperiodicallycutoff,themagneticfieldisshutdo-wn,andthecanisterbackwashedwithwatertoclearoutaccumulatedmagneticcontaminants.第40頁/共62頁5.2Typeofmagneticseparator

Superconductingmagneticseparator

(超導磁選機）

Anopen-gradientdrummagneticseparatorwithasuperconductingmagnetsy-stemhasbeenoperatingcommerciallysincethelate1980s.Althoughseparationisidenticaltothatinconventionaldrumseparators,themagneticfluxdensityatthedrumsurfacecanreachover4T,generatedbythesuperconductivemagnetassemblywithinthedrum.第41頁/共62頁Magneticandelectricalseparation5.3Practiceofmagneticseparation5.2Typeofmagneticseparator5.4Electricalseparation5.1MagneticseparationChapter55.5Practiceofelectricalseparation第42頁/共62頁5.3Practiceofmagneticseparation

Magneticseparationofironore

(鐵礦石磁選）我國具有代表性的鐵礦種類：（1）鞍山式鐵礦是我國最重要的鐵礦床。礦石中金屬礦物以磁鐵礦為主，其次是赤鐵礦、菱鐵礦；脈石礦物有石英、綠泥石、角閃石、云母、長石和方解石等。（2）鏡鐵山式鐵礦主要分布在我國西北部甘肅境內(nèi)，礦石中主要金屬礦物為鏡鐵礦、菱鐵礦等，共生有價礦物為重晶石。脈石礦物主要為碧玉、鐵白云石等。（3）攀枝花式鐵礦是一種伴生釩、鈦、鈷等多種元素的磁鐵礦，其礦石儲量居我國鐵礦總儲量的第二位。礦石中主要金屬礦物有含釩鈦磁鐵礦、鈦鐵礦，硫化物以磁黃鐵礦為主。根據(jù)含鐵礦物的不同，有工業(yè)價值的鐵礦石主要有：磁鐵礦石、赤鐵礦石、褐鐵礦石、菱鐵礦石和混合型鐵礦石（赤鐵礦一磁鐵礦混合礦石、含鈦磁鐵礦石、含銅磁鐵礦石）等。第43頁/共62頁5.3Practiceofmagneticseparation

Magneticseparationofironore

(鐵礦石磁選）

1）攀枝花釩鈦磁鐵礦選礦

第44頁/共62頁5.3Practiceofmagneticseparation

Magneticseparationofironore

(鐵礦石磁選）

2）弱磁性鐵礦物的磁化焙燒與弱磁選

磁化焙燒是礦石加熱到一定溫度后在相應(yīng)氣氛中進行物理化學反應(yīng)的過程。焙燒磁化產(chǎn)物一般用弱磁選的方法進行分選。典型的（酒鋼選礦廠）生產(chǎn)流程見圖。

3）弱磁性鐵礦物的強磁選

瓊斯?jié)袷綇姶胚x機被大量用于氧化鐵礦石的磁選。第45頁/共62頁5.3Practiceofmagneticseparation

Magneticseparationofmanganeseore

(錳礦磁選）

錳礦物屬于弱磁性礦物，其比磁化率與脈石礦物的差別較大，因此，錳礦石的強磁選占有重要的地位。對組成比較簡單、嵌布粒度較粗的碳酸錳礦石和氧化錳礦石用單一磁選流程可獲得較好的分選指標。圖示為湖南桃江錳礦強磁選流程。第46頁/共62頁5.3Practiceofmagneticseparation

Magneticseparationofnon-ferrousandraremetalsore

(有色和稀有金屬礦石磁選）

鎢粗精礦的精選

黑鎢礦屬于弱磁性礦物，而錫石、白鎢礦是非磁性礦物，因此，利用磁選法可將它們分開。我國某鎢礦精煉廠鎢粗精礦磁選精選流程如圖所示。第47頁/共62頁5.3Practiceofmagneticseparation

Magneticseparationofnon-metallicminerals

(非金屬礦物的磁選）

1）工業(yè)礦物的提純

工業(yè)礦物（如石英、藍晶石、粘土礦物等）中的鐵和鈦氧化物是有害雜質(zhì)。現(xiàn)代高梯度磁分離技術(shù)的發(fā)展能使40多種工業(yè)礦物用這種方法提純。高嶺土也稱瓷土，主要成分是高嶺石礦物(Al2O3SiO2·2H2O)，一種含水鋁硅酸鹽，用于造紙工業(yè)的填料和涂料、陶瓷和耐火材料及油漆顏料等。無論紙張或是陶瓷，白色的光潔面極為重要。影響白度的主要物質(zhì)是原料中的少量含鐵礦物，如氧化鐵等，占總量的0.5％～3％。為了脫除影響白度的含鐵成分，可采用高梯度磁選法來實現(xiàn)。第48頁/共62頁5.3Practiceofmagneticseparation

Magneticseparationofnon-metallicminerals

(非金屬礦物的磁選）

2）煤的脫硫

煤可以用高梯度磁選、開梯度磁選等方法脫硫降灰，但現(xiàn)在還沒有大規(guī)模運用到實際生產(chǎn)中。據(jù)有關(guān)介紹，用磁感應(yīng)強度為2T、磁介質(zhì)為直徑100μm的鋼毛、充填率10％的高梯度磁選機，對巴西煤脫硫，無機硫排除率達80％以上。對微米級的弗里波特（Freeport）煤，當磁感應(yīng)強度為2T時。灰分可以從16.3％降到6.5％。進一步降至4％時磁感應(yīng)強度需高達15T。第49頁/共62頁Magneticandelectricalseparation5.3Practiceofmagneticseparation5.2Typeofmagneticseparator5.4Electricalseparation5.1MagneticseparationChapter55.5Practiceofelectricalseparation第50頁/共62頁5.4ElectricalseparationElectricalseparationutilisesthedifferenceinelectricalconductivitybetweenthevariousmineralsintheorefeed.Sincealmostallmineralsshowsomediffer-enceinconductivityitwouldappeartorepresenttheuniversalconcentratingm-ethod.I