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翻译英文原文COMMINUTIONINANON-CYLINDRICALROLLCRUSHER*P.VELLETRIandD.M.WEEDONDept.ofMechanical&MaterialsEngineering,UniversityofWesternAustralia,35StirlingHwv,Crawley6009,Australia.E-.auFacultyofEngineeringandPhysicalSystems,CentralQueenslandUniversity,POBox1!:；19,Gladstone,Qld.4680,Australia(Received3May2001；accepted4September2001)ABSTRACTLowreductionratiosandhighwearratesarethetwocharacteristicsntostcommonhassociatedwithconventionalrollcrushers.Becauseofthis,rollcrushersarenotoftenconsideredJoruseinmineralprocessingcircuits,attdmanyoftheiradvantagesarebeinglargelyoverlooked.Thispaperdescribesanovelrollcrusherthathasbeendevelopediptordertoaddresstheseissues.RelbrredtoastheNCRC(Non-CylindricalRollCrusher),thenewcrusherincorporatestworollscomprisedqfanalternatingarrangementofplatteattdconvexorconcavesuwes.Theseuniquerollprqfilesimprovetheangleqfnip,enablingtheNCRCtoachievehigherreductionratiosthanconventionalrollcrushers.Testswithamodelprototypehaveindicatedtharevellfi)rveryhardores,reductionratiosexceedinglO:lcanbeattained.Inaddition,sincethecomminutionprocessintheNCRCcombinestheactionsofrollarMjawcrushersthereisapossibiliOthatthenewprofilesmayleadtoreducedrollwearrates.2001ElsevierScienceLtd.Allrightsreserved.Keywords:Comminution；crushingINTRODUCTIONConventionalrollcrusherssufferfromseveraldisadvantagesthathavelcdtotheirlackofpopularityinmineralprocessingapplications.Inparticular,theirlowreductionratios(typicallylimitedtoabout3:1)andhighwearratesmakethemunattractivewhencomparedtoothertypesofcomminutionequipment,suchasconecrushers.Thereare,however,somecharacteristicsofrollcrushersthatareverydesirablefromamineralprocessingpointofview.Therelativelyconstantoperatinggapinarollcrushergivesgoodcontroloverproductsize.Theuseofspring-loadedrollsmakethesemachinestoleranttouncrushablematerial(suchastrampmetal).Inaddition,rollcrushersworkbydrawingmaterialintothecompressionregionbetweentherollsanddonotrelyongravitationalfeecilikeconeandjawcrushers.Thisgeneratesacontinuouscrushingcycle,whichyieldshighthroughputratesandalsomakesthecrushercapableofprocessingwetandstickyore.TheNCRCisanovelrollcrusherthathasbeendcvelopedattheUniversityofWesternAustraliainordcrtoaddresssomeoftheproblemsassociatedwithconventionalrollcrushers.Thenewcrusherincorporatestworollscomprisedofanalternatingarrangementofplaneandconvexorconcavesurfaccs.Thcseuniquerollprofilesimprovetheangleofnip,enablingtheNCRCtoachievehigherreductionratiosthanconventionalrollcrushers.Preliminarytestswithamodelprototypehaveindicatedthat,evenforveryhardoics,reductionratiosexceeding10:Icanbeattained(VellelriandWeedon,2000).Theseinitialfindingswereobtainedforsingleparticlefeed.wherethereisnosignificantinteractionbetweenparticlesduringcomminution.Thecurrentworkextendstheexistingresultsbvexamininginulti-particlecomminutionintheNCRC.ItalsolooksatvariousothcrfactorsthatinfluencctheperlirmanceoftheNCRCandexplorestheeffectivenessofusingtheNCRCfortheprocessingofmillscats.PRINCIPLEOFOPERATIONTheangleofnipisoneofthemainlectorseffcctingtheperformanceofarollcrusher.Smallernipanglesarebeneficialsincetheyincreasetlelikelihoodofparlictesbcinggrabbedandcrushedbylherolls.Foragivenfeedsizeandrollgap,thenipangleinaconventionalrtHlcrusherislimitedbythesizeofthcrolls.TheNCRCattemptstoovercomethislimitationthroughtheuseofprofiledrolls,whichimprovetheangleofnipatvariouspointsduringonecycle(orrevolution)oftherolls.Inadditiontothenipangle,anumberofotherfactorsincludingvariationmrollgapandmodeofcommmutionwereconsideredwhenselectingIllerollprofiles.ThefinalshapesoftheNCRCrollsareshowninFigureI.OneoftherollsconsistssIanalternatingarrangementofplaneandconvexsurfaces,whiletheotherisformedfromanalternatingarrangementofphmeandconcavesurlaccs.TheshapeoftherollsontheNCRCresultinseveraluniquecharacteristics.Tilemostimportantisthat,lk)ragivenparticlesizeandrollgap,thenipanglegeneratedmtheNCRCwillnotremainconstantastherollsrotate.Therewillbetimeswhenthenipangleismuchlowerthanitwouldbeforthesamesizedcylindricalrollsandtimeswhenitwillbemuchhighcr.Theactualvariationinnipangleovera60degreerollrotationisillustratedinFigure2,whichalsoshowsthenipanglegeneratedundersimilarconditionsmacylindricalrollcrusherofcomparablesize.Thesenipangleswerecalculatedfora25ramdiametercircularparticlebetweenrollofapproximately200ramdiametersetataImmminimumgap.Thisexamplecanbeusedtoillustratethepotentialadvantageofusingnon-cylindricalrolls.Inorderforaparticletobegripped,thcangleofnipshouldnormallynotexceed25.Thus,thecylindricalrollcrusherwouldnevernipthisparticle,sincetheactualnipangleremainsconstantatapproximately52.ThenipanglegeneratedbytheNCRC,however,tidlsbelow25onceastherollsrotateby(0degrees.Thismeansthatthenon-cylindricalrollshaveapossibilityofnippingtheparticlc6timesduringonerollrewHution.EXPERIMENTALPROCEDUREThelaboratoryscaleprototypeoftheNCRC(Figure3)consistsoftworollunits,eachcomprisingamotor,gearboxandprofiledroll.Bothunitsaremountedonlinearbearings,whicheffectivelysupportanyverticalcomponcntofforcewhileenablinghorizontalmotion.Onerollunitishorizontallyfixedwhiletheotherisrestrainedviaacompressionspring,whichallowsittoresistavaryingdegreeofhorizontalload.Thepre-loadonthemovablerollcanbeadjusteduptoamaximumof20kN.Thetwomotorsthatdrivetherollsareelectronicallysynchronisedthroughavariablespeedcontroller,enablingtherollspeedtobecontinuouslyvariedupto14rpm(approximately0.14m/ssurfacespeed).Therollshaveacentre-to-centredistance,atzerogapsetting)ofI88mmandawidthof100mm.Bothdriveshaftsareinstrumentedwithstraingaugestoenabletherolltorquetobemeasured.Additionalsensorsareprovidedtomeasurethehorizontalforceonthestationaryrollandthegapbetweentherolls.ClearglassisfittedtothesidesoftheNCRCtofacilitateviewingofthecrushingzoncduringoperationandalsoallowsthecrushingsequencetobcrecordedusingahigh-speeddigitalcamera.Testswereperformedonseveraltypesofrocksincludinggranite,diorite,mineralore,millscatsandconcrete.Thegraniteanddioritewereobtainedfromseparatecommercialquarries；theformerhadbeenpre-crushedandsized,whilethelatterwasas-blastedrock.ThefirstoftheoresampleswasSAGmillfeedobtainedfromNormandyMiningsGoldenGroveoperations,whilethemillscatswereobtainedfromAuroraGoldsMtMurominesiteincentralKalimantan.Themillscatsincludedmetalparticlesofupto18ramdiameterfromwornandbrokengrindingmedia.Theconcreteconsistedofcylindricalsamples(25mmdiameterby25ramhigh)thatwerepreparedinthelaboratoryinaccordancewiththerelevantAustralianStandards.Unconfineduniaxialcompressiontestswereperformedoncoresamples(25mmdiameterby25mmhigh)takenfromanumberoftheores.Theresultsindicatedstrengthrangingfrom60MPaforthepreparedconcreteupto260MPafortheGoldenGroveoresamples.Allofthesampleswereinitiallypassedthrougha37.5mmsievetoremoveanyoversizedparticles.Theundersizedorewasthensampledandsievedtodeterminethefeedsizedistribution.Foreachtrialapproximately2500gofsamplewascrushedintheNCRC.Thissamplesizewaschosenonthebasisofstatisticaltests,whichindicatedthatatleast2000gofsampleneededtobecrushedinordertoestimatetheproductP80towithin+0.1ramwith95%confidence.Theproductwascollectedandriffledi