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外文翻译--破碎机.doc

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外文翻译--破碎机.doc

翻译英文原文COMMINUTIONINANONCYLINDRICALROLLCRUSHERP.VELLETRIandD.M.WEEDONDept.ofMechanicalMaterialsEngineering,UniversityofWesternAustralia,35StirlingHwv,Crawley6009,Australia.Emailpieromech.uwa.edu.au§FacultyofEngineeringandPhysicalSystems,CentralQueenslandUniversity,POBox119,Gladstone,Qld.4680,AustraliaReceived3May2001accepted4September2001ABSTRACTLowreductionratiosandhighwearratesarethetwocharacteristicsntostcommonhassociatedwithconventionalrollcrushers.Becauseofthis,rollcrushersarenotoftenconsideredJoruseinmineralprocessingcircuits,attdmanyoftheiradvantagesarebeinglargelyoverlooked.Thispaperdescribesanovelrollcrusherthathasbeendevelopediptordertoaddresstheseissues.RelbrredtoastheNCRCNonCylindricalRollCrusher,thenewcrusherincorporatestworollscomprisedqfanalternatingarrangementofplatteattdconvexorconcavesuwes.Theseuniquerollprqfilesimprovetheangleqfnip,enablingtheNCRCtoachievehigherreductionratiosthanconventionalrollcrushers.Testswithamodelprototypehaveindicatedtharevellfirveryhardores,reductionratiosexceedinglOlcanbeattained.Inaddition,sincethecomminutionprocessintheNCRCcombinestheactionsofrollarMjawcrushersthereisapossibiliOthatthenewprofilesmayleadtoreducedrollwearrates.©2001ElsevierScienceLtd.Allrightsreserved.KeywordsComminutioncrushingINTRODUCTIONConventionalrollcrusherssufferfromseveraldisadvantagesthathavelcdtotheirlackofpopularityinmineralprocessingapplications.Inparticular,theirlowreductionratiostypicallylimitedtoabout31andhighwearratesmakethemunattractivewhencomparedtoothertypesofcomminutionequipment,suchasconecrushers.Thereare,however,somecharacteristicsofrollcrushersthatareverydesirablefromamineralprocessingpointofview.Therelativelyconstantoperatinggapinarollcrushergivesgoodcontroloverproductsize.Theuseofspringloadedrollsmakethesemachinestoleranttouncrushablematerialsuchastrampmetal.Inaddition,rollcrushersworkbydrawingmaterialintothecompressionregionbetweentherollsanddonotrelyongravitationalfeecilikeconeandjawcrushers.Thisgeneratesacontinuouscrushingcycle,whichyieldshighthroughputratesandalsomakesthecrushercapableofprocessingwetandstickyore.TheNCRCisanovelrollcrusherthathasbeendcvelopedattheUniversityofWesternAustraliainordcrtoaddresssomeoftheproblemsassociatedwithconventionalrollcrushers.Thenewcrusherincorporatestworollscomprisedofanalternatingarrangementofplaneandconvexorconcavesurfaccs.Thcseuniquerollprofilesimprovetheangleofnip,enablingtheNCRCtoachievehigherreductionratiosthanconventionalrollcrushers.Preliminarytestswithamodelprototypehaveindicatedthat,evenforveryhardoics,reductionratiosexceeding10IcanbeattainedVellelriandWeedon,2000.Theseinitialfindingswereobtainedforsingleparticlefeed.wherethereisnosignificantinteractionbetweenparticlesduringcomminution.ThecurrentworkextendstheexistingresultsbvexamininginultiparticlecomminutionintheNCRC.ItalsolooksatvariousothcrfactorsthatinfluencctheperlirmanceoftheNCRCandexplorestheeffectivenessofusingtheNCRCfortheprocessingofmillscats.PRINCIPLEOFOPERATIONTheangleofnipisoneofthemainlectorseffcctingtheperformanceofarollcrusher.Smallernipanglesarebeneficialsincetheyincreasetlelikelihoodofparlictesbcinggrabbedandcrushedbylherolls.Foragivenfeedsizeandrollgap,thenipangleinaconventionalrtHlcrusherislimitedbythesizeofthcrolls.TheNCRCattemptstoovercomethislimitationthroughtheuseofprofiledrolls,whichimprovetheangleofnipatvariouspointsduringonecycleorrevolutionoftherolls.Inadditiontothenipangle,anumberofotherfactorsincludingvariationmrollgapandmodeofcommmutionwereconsideredwhenselectingIllerollprofiles.ThefinalshapesoftheNCRCrollsareshowninFigureI.Oneoftherollsconsists{sIanalternatingarrangementofplaneandconvexsurfaces,whiletheotherisformedfromanalternatingarrangementofphmeandconcavesurlaccs.TheshapeoftherollsontheNCRCresultinseveraluniquecharacteristics.Tilemostimportantisthat,lkragivenparticlesizeandrollgap,thenipanglegeneratedmtheNCRCwillnotremainconstantastherollsrotate.Therewillbetimeswhenthenipangleismuchlowerthanitwouldbeforthesamesizedcylindricalrollsandtimeswhenitwillbemuchhighcr.Theactualvariationinnipangleovera60degreerollrotationisillustratedinFigure2,whichalsoshowsthenipanglegeneratedundersimilarconditionsmacylindricalrollcrusherofcomparablesize.Thesenipangleswerecalculatedfora25ramdiametercircularparticlebetweenrollofapproximately200ramdiametersetataImmminimumgap.Thisexamplecanbeusedtoillustratethepotentialadvantageofusingnoncylindricalrolls.Inorderforaparticletobegripped,thcangleofnipshouldnormallynotexceed25°.Thus,thecylindricalrollcrusherwouldnevernipthisparticle,sincetheactualnipangleremainsconstantatapproximately52°.ThenipanglegeneratedbytheNCRC,however,tidlsbelow25°onceastherollsrotateby0degrees.Thismeansthatthenoncylindricalrollshaveapossibilityofnippingtheparticlc6timesduringonerollrewHution.EXPERIMENTALPROCEDUREThelaboratoryscaleprototypeoftheNCRCFigure3consistsoftworollunits,eachcomprisingamotor,gearboxandprofiledroll.Bothunitsaremountedonlinearbearings,whicheffectivelysupportanyverticalcomponcntofforcewhileenablinghorizontalmotion.Onerollunitishorizontallyfixedwhiletheotherisrestrainedviaacompressionspring,whichallowsittoresistavaryingdegreeofhorizontalload.Thepreloadonthemovablerollcanbeadjusteduptoamaximumof20kN.Thetwomotorsthatdrivetherollsareelectronicallysynchronisedthroughavariablespeedcontroller,enablingtherollspeedtobecontinuouslyvariedupto14rpmapproximately0.14m/ssurfacespeed.Therollshaveacentretocentredistance,atzerogapsettingofI88mmandawidthof100mm.Bothdriveshaftsareinstrumentedwithstraingaugestoenabletherolltorquetobemeasured.Additionalsensorsareprovidedtomeasurethehorizontalforceonthestationaryrollandthegapbetweentherolls.ClearglassisfittedtothesidesoftheNCRCtofacilitateviewingofthecrushingzoncduringoperationandalsoallowsthecrushingsequencetobcrecordedusingahighspeeddigitalcamera.Testswereperformedonseveraltypesofrocksincludinggranite,diorite,mineralore,millscatsandconcrete.Thegraniteanddioritewereobtainedfromseparatecommercialquarriestheformerhadbeenprecrushedandsized,whilethelatterwasasblastedrock.ThefirstoftheoresampleswasSAGmillfeedobtainedfromNormandyMiningsGoldenGroveoperations,whilethemillscatswereobtainedfromAuroraGoldsMtMurominesiteincentralKalimantan.Themillscatsincludedmetalparticlesofupto18ramdiameterfromwornandbrokengrindingmedia.Theconcreteconsistedofcylindricalsamples25mmdiameterby25ramhighthatwerepreparedinthelaboratoryinaccordancewiththerelevantAustralianStandards.Unconfineduniaxialcompressiontestswereperformedoncoresamples25mmdiameterby25mmhightakenfromanumberoftheores.Theresultsindicatedstrengthrangingfrom60MPaforthepreparedconcreteupto260MPafortheGoldenGroveoresamples.Allofthesampleswereinitiallypassedthrougha37.5mmsievetoremoveanyoversizedparticles.Theundersizedorewasthensampledandsievedtodeterminethefeedsizedistribution.Foreachtrialapproximately2500gofsamplewascrushedintheNCRC.Thissamplesizewaschosenonthebasisofstatisticaltests,whichindicatedthatatleast2000gofsampleneededtobecrushedinordertoestimatetheproductP80towithin0.1ramwith95confidence.Theproductwascollectedandriffledintotensubsamples,andastandardwet/drysievingmethodwasthenusedtodeterminetheproductsizedistribution.Foreachtrial,twoofthesubsampleswereinitiallysieved.Additionalsubsamplesweresievediftherewereanysignificantdifferencesintheresultingproductsizedistributions.AnumberofcomminutiontestswereconductedusingtheNCRCtodeterminetheeffectsofvariousparametersincludingrollgap,rollforce,feedsize,andtheeffectofsingleandmultiparticlefeed.Therollspeedwassetatmaximumandwasnotvariedbetweentrialsaspreviousexperimentshadconcludedthattherewaslittleeffectofrollspeedonproductsizedistribution.Itshouldbenotedthattherollgapsettingsquotedrefertotheminimumrollgap.Duetothenoncylindricalshapeoftherolls,theactualrollgapwillvaryupto1.7mmabovetheminimumsettingiearollgapsellingoflmmactuallymeans12.7mmroll

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