非圆柱辊破碎机的粉碎外文翻译Word文档格式.docx
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非圆柱辊破碎机的粉碎外文翻译Word文档格式.docx
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Lowreductionratiosandhighwearratesarethetwocharacteristicsntostcommonh"
associatedwithconventionalrollcrushers.Becauseofthis,rollcrushersarenotoftenconsideredJoruseinmineralprocessingcircuits,attdmanyoftheiradvantagesarebeinglargelyoverlooked.Thispaperdescribesanovelrollcrusherthathasbeendevelopediptordertoaddresstheseissues.RelbrredtoastheNCRC(Non-CylindricalRollCrusher),thenewcrusherincorporatestworollscomprisedqfanalternatingarrangementofplatteattdconvexorconcavesu@wes.Theseuniquerollprqfilesimprovetheangleqfnip,enablingtheNCRCtoachievehigherreductionratiosthanconventionalrollcrushers.Testswithamodelprototypehaveindicatedtharevellfi)rveryhardores,reductionratiosexceedinglO:
lcanbeattained.Inaddition,sincethecomminutionprocessintheNCRCcombinestheactionsofrollarMjawcrushersthereisapossibiliO'
thatthenewprofilesmayleadtoreducedrollwearrates.
Keywords:
Comminution;
crushing
INTRODUCTION
Conventionalrollcrusherssufferfromseveraldisadvantagesthathavelcdtotheirlackofpopularityinmineralprocessingapplications.Inparticular,theirlowreductionratios(typicallylimitedtoabout3:
1)andhighwearratesmakethemunattractivewhencomparedtoothertypesofcomminutionequipment,suchasconecrushers.Thereare,however,somecharacteristicsofrollcrushersthatareverydesirablefroma
mineralprocessingpointofview.Therelativelyconstantoperatinggapinarollcrushergivesgoodcontroloverproductsize.Theuseofspring-loadedrollsmakethesemachinestoleranttouncrushablematerial(suchastrampmetal).Inaddition,rollcrushersworkbydrawingmaterialintothecompressionregionbetweentherollsanddonotrelyongravitationalfeeci~likeconeandjawcrushers.Thisgeneratesacontinuouscrushingcycle,whichyieldshighthroughputratesandalsomakesthecrushercapableofprocessingwetandstickyore.
TheNCRCisanovelrollcrusherthathasbeendcvelopedattheUniversityofWesternAustraliainordcrtoaddresssomeoftheproblemsassociatedwithconventionalrollcrushers.Thenewcrusherincorporatestworollscomprisedofanalternatingarrangementofplaneandconvexorconcavesurfaccs.Thcseuniquerollprofilesimprovetheangleofnip,enablingtheNCRCtoachievehigherreductionratiosthanconventionalrollcrushers.Preliminarytestswithamodelprototypehaveindicatedthat,evenforveryhardoics,reductionratiosexceeding10:
Icanbeattained(VellelriandWeedon,2000).Theseinitialfindingswereobtainedforsingleparticlefeed.wherethereisnosignificantinteractionbetweenparticlesduringcomminution.Thecurrentworkextendstheexistingresultsbvexamininginulti-particlecomminutionintheNCRC.Italsolooksatvariousothcrfactorsthatinfluencctheperli~rmanceoftheNCRCandexplorestheeffectivenessofusingtheNCRCfortheprocessingofmillscats.
PRINCIPLEOFOPERATION
Theangleofnipisoneofthemainlectorseffcctingtheperformanceofarollcrusher.Smallernipanglesarebeneficialsincetheyincreasetl~elikelihoodofparlictesbcinggrabbedandcrushedbylherolls.Foragivenfeedsizeandrollgap,thenipangleinaconventionalrtHlcrusherislimitedbythesizeofthcrolls.
TheNCRCattemptstoovercomethislimitationthroughtheuseofprofiledrolls,whichimprovetheangleofnipatvariouspointsduringonecycle(orrevolution)oftherolls.Inadditiontothenipangle,anumberofotherfactorsincludingvariationmrollgapandmodeofcommmutionwereconsideredwhenselectingIllerollprofiles.ThefinalshapesoftheNCRCrollsareshowninFigureI.Oneoftherollsconsists{sIanalternatingarrangementofplaneandconvexsurfaces,whiletheotherisformedfromanalternatingarrangementofphmeandconcavesurlaccs.
TheshapeoftherollsontheNCRCresultinseveraluniquecharacteristics.Tilemostimportantisthat,lk)ragivenparticlesizeandrollgap,thenipanglegeneratedmtheNCRCwillnotremainconstantastherollsrotate.Therewillbetimeswhenthenipangleismuchlowerthanitwouldbeforthesamesizedcylindricalrollsandtimeswhenitwillbemuchhighcr.Theactualvariationinnipangleovera60degreerollrotationisillustratedinFigure2,whichalsoshowsthenipanglegeneratedundersimilarconditionsmacylindricalrollcrusherofcomparablesize.Thesenipangleswerecalculatedfora25ramdiametercircularparticlebetweenrollofapproximately200ramdiametersetataImmminimumgap.Thisexamplecanbeusedtoillustratethepotentialadvantageofusingnon-cylindricalrolls.Inorderforaparticletobegripped,thcangleofnipshouldnormallynotexceed25°
.Thus,thecylindricalrollcrusherwouldnevernipthisparticle,sincetheactualnipangleremainsconstantatapproximately52°
.ThenipanglegeneratedbytheNCRC,however,tidlsbelow25°
onceastherollsrotateby(~0degrees.Thismeansthatthenon-cylindricalrollshaveapossibilityofnippingtheparticlc6timesduringonerollrewHution.
EXPERIMENTALPROCEDURE
ThelaboratoryscaleprototypeoftheNCRC(Figure3)consistsoftworollunits,eachcomprisingamotor,gearboxandprofiledroll.Bothunitsaremountedonlinearbearings,whicheffectivelysupportanyverticalcomponcntofforcewhileenablinghorizontalmotion.Onerollunitishorizontallyfixedwhiletheotherisrestrainedviaacompressionspring,whichallowsittoresistavaryingdegreeofhorizontalload.
Thepre-loadonthemovablerollcanbeadjusteduptoamaximumof20kN.Thetwomotorsthatdrivetherollsareelectronicallysynchronisedthroughavariablespeedcontroller,enablingtherollspeedtobecontinuouslyvariedupto14rpm(approximately0.14m/ssurfacespeed).Therollshaveacentre-to-centredistance~,atzerogapsetting)ofI88mmandawidthof100mm.Bothdriveshaftsareinstrumentedwithstraingaugestoenabletherolltorquetobemeasured.Additionalsensorsareprovidedtomeasurethehorizontalforceonthestationaryrollandthegapbetweentherolls.ClearglassisfittedtothesidesoftheNCRCtofacilitateviewingofthecrushingzoncduringoperationandalsoallowsthecrushingsequenceto
bcrecordedusingahigh-speeddigitalcamera.
Testswereperformedonseveraltypesofrocksincludinggranite,diorite,mineralore,millscatsandconcrete.Thegraniteanddioritewereobtainedfromseparatecommercialquarries;
theformerhadbeenpre-crushedandsized,whilethelatterwasas-blastedrock.ThefirstoftheoresampleswasSAGmillfeedobtainedfromNormandyMining'
sGoldenGroveoperations,whilethemillscatswereobtainedfromAuroraGold'
sMtMurominesiteincentralKalimantan.Themillscatsincludedmetalparticlesofupto18ramdiameterfromwornandbrokengrindingmedia.Theconcreteconsistedofcylindricalsamples(25mmdiameterby25ramhigh)thatwerepreparedinthelaboratoryinaccordancewiththerelevantAustralianStandards.Unconfineduniaxialcompressiontestswereperformedoncoresamples(25mmdiameterby25mmhigh)takenfromanumberoftheores.Theresultsindicatedstrengthrangingfrom60MPaforthepreparedconcreteupto260MPafortheGoldenGroveoresamples.
Allofthesampleswereinitiallypassedthrougha37.5mmsievetoremoveanyoversizedparticles.Theundersizedorewasthensampledandsievedtodeterminethefeedsizedistribution.Foreachtrialapproximately2500gofsamplewascrushedintheNCRC.Thissamplesizewaschosenonthebasisofstatisticaltests,whichindicatedthatatleast2000gofsampleneededtobecrushedinordertoestimatetheproductP80towithin+0.1ramwith95%confidence.Theproductwascollectedandriffledintotensubsamples,andastandardwet/drysievingmethodwasthenusedtodeterminetheproductsizedistribution.Foreachtrial,twoofthesub-sampleswereinitiallysieved.Additionalsub-samplesweresievediftherewereanysignificantdifferencesintheresultingproductsizedistributions.AnumberofcomminutiontestswereconductedusingtheNCRCtodeterminetheeffectsofvariousparametersincludingrollgap,rollforce,feedsize,andtheeffectofsingleandmulti-particlefeed.Therollspeedwassetatmaximumandwasnotvariedbetweentrialsaspreviousexperimentshadconcludedthattherewaslittleeffectofrollspeedonproductsizedistribution.Itshouldbenotedthattherollgapsettingsquotedrefertotheminimumrollgap.Duetothenon-cylindricalshapeoftherolls,theactualrollgapwillvaryupto1.7mmabovetheminimumsetting(ie:
arollgapsellingoflmmactuallymeans1-2.7mmroll.
RESULTS
Feedmaterial
Theperformanceofallcomminutionequipmentisdependentonthetypeofmaterialbeingcrushed.Inthisrespect,theNCRCisnodifferent.SoftermaterialscrushedintheNCRCyieldalowerP80thanhardermaterials.Figure4showstheproductsizedistributionobtainedwhenseveraldifferentmaterialswerecrushedundersimilarconditionsintheNCRC.Itisinterestingtonotethatapartfromthepreparedconcretesamples,theP80valuesobtainedfromthevariousmaterialswerefairlyconsistent.TheseresultsreflectthedegreeofcontroloverproductsizedistributionthatcanbeobtainedwiththeNCRC.
Multiplefeedparticles
PrevioustrialswiththeNCRCwereconductedusingonlysinglefeedparticleswheretherewaslittleornointeractionbetweenparticles.Althoughveryeffective,thelowthroughputratesassociatedwiththismodeofcomminutionmakesitunsuitableforpracticalapplications.Thereforeitwasnecessarytodeterminetheeffectthatacontin
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