文献翻译颚式破碎机在花岗岩采掘中受岩石强度性能的影响文档格式.docx

文献翻译颚式破碎机在花岗岩采掘中受岩石强度性能的影响文档格式.docx

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Abstract：

TheinfluenceofrockstrengthpropertiesonJawCrusherperformancewascarriedouttodeterminetheeffectofrockstrengthoncrushingtimeandgrainsizedistributionoftherocks．Investigationwasconductedonfourdifferentrocksamplesnamelymarble．dolomite．1imestoneandgranitewhichwererepresentativelyselectedfromfragmentedlumpsinquarries．UnconfinedcompressivestrengthandPointloadtestswerecarriedoutoneachrocksampleaswellascrushingtimeandsizeanalysis．Theresultsofthestrengthparametersofeachsamplewerecorrelatedwiththecrushingtimeandthegrainsizedistributionoftherocktypes。

Theresultsofthestrengthtestsshowthatgranitehasthehighestmeanvalueof101.67MPaforUnconfinedCompressiveStrength（UCS）test．6.43MPaforPointLoadtestwhiledolomitehastheleastmeanvalueof30.56MPaforUCStestand0.95MPaforPointLoadtest。

AccordingtotheInternationalSocietyforRockMechanicOSRM）standard．thegraniterocksamplemaybeclassifiedashavingveryhighstrengthanddolomiterocksample，lowstrength．Also，thegraniterockhasthehighestcrushingtime（21．Os）anddolomiterockhastheleastvalue（5．0s）．Basedontheresultsoftheinvestigation，itwasfoundoutthatthereisagreatinfluenceofstrengthpropertiesoncrushingtimeofrocktypes．

1Introduction

Thestrengthofamaterialreferstothematerialsabilitytoresistanappliedforce．Strengthpropertyofrockistheabilityoftherockmaterialtoresistfailurewhenloadisappliedwithoutyieldingorfracture．Themechanicalpropertiesofrockdependupontheinteractionbetweenthecrystals，particlesandcementationmaterialofwhichitiscomposed．Theyieldstrengthofamaterialisanadequateindicatorofthematerial’smechanicalstrengthandistheparameterthatpredictsplasticdeformationinthematerial．fromwhichonecanmakeinformeddecisionsonhowtoincreasethestrengthofamaterialdependingonitsmicro-structuralpropertiesandthedesiredendeffect．Strengthisconsideredintermsofcompressivestrength，tensilestrength，andshearstrength，namelythelimitstatesofcompressivestress，tensilestressandshearstress，respectively．AccordingtoReference，theeffectofdynamicloadingisprobablythemostimportantpracticalpartofthestrengthofmaterials，especiallytheproblemoffatigue．Repeatedloadingofteninitiatesbrittlecracks，whichgrowslowlyuntilfailureoccurs．Itisofparamountimportancetofirstcarryoutsizereductionofanoreorrockmaterialonalaboratoryscalefortheoreorrockmaterialtobeprofitablyandeconomicallyprocessedindustrially．Thispermitsthedeterminationofparameterssuchasliberationsize，grindability，coarsetomediumtofineproportioninanyproductofthecrushingandgrindingequipmentandtheproportionofvaluesofganguesinthefines．JawCrusherisusedforcrushingrockmaterialinminesandquarries。

Itprovidesthelatesttechnologyinheavydutycrusherdesignthatdelivershighproduction，infinitesettingadjustment，largerfeedopeningboltedmainframe，castswing，jawholderandoptionalpositioningofthecrushersupportfeettosuitinstallationrequirement．Thiscrusherisdesignedforexceptionalheavyandcontinuousapplicationwithheavydutypartforoptimumoperationandlonglifeandthiscanbeinfluencedbythestrengthpropertiesoftherock．Theinfluenceofrockstrengthpropertycanresulttothelossofcapacitytoperformthestipulatedfunctionforwhichjawcrusherwasdesigned．TheUCSwasthemainquantitativemethodforcharacterizingthestrengthofrockmaterials．Pointloadtestisusedtodeterminerockstrengthindexesingeotechnicalpractice．Rocklithologieswereclassifiedintogeneralcategoriesandconversionfactorsweredeterminedforeachcategory．ThisallowsforintactrockstrengthdatatobemadeavailablethroughpointloadtestingfornumericalgeotechnicalanalysisandempiricalrockmassclassificationsystemssuchastheCoalMineRoofRating（CMRR）．

Crushingisanintegralportionformineralprocessingoperationsandiscriticalforthepreparationoforefordownstreamprocessformineralprocessingoperations．Crushingofquarriedrockiscarriedoutinstages，withtheprimarycrushingstagetypicallycarriedoutusingjawcrusherandsubsequent（secondaryandtertiary）．Fromfieldobservation，thegreaterthenumberofcrushingstage，thehighertheamountoffineproducedasaproportionoftotalplantthroughout．Thetypeofcrusherusedalsodirectlycontrolstheamountoffinesproduced．Arecentstudyofquarryfineslookedatpossiblerelationshipbetweenquarryplantoperationandthegenerationofquarryfines．Theconclusiondrawnhavebeencriticallyrevealedthathardrockaggregateplantproductionisdirectlyproportionaltothenumberofcrushingstages；

itincreaseswithanincreaseinproductionstage．Lowreductionfinesgenerationateachstageespeciallywheretherockormineralarefragile，however，thecumulativefinesproductionmaybehigherthanaprocessusingfewerstageswithhigherreduction．

Thepaniclesizeanalysisisthemethodusedtodeterminetheparticlesizedistributionorthegrainsizedistributionofrock／orematerials．Inpractice，closesizecontroloffeedtomineralprocessingequipmentisrequiredinordertoreducethesizeeffectandmaketherelativemotionoftheparticlesseparationdependent．Theparticlesizedistributionofamatedalisimportantinunderstandingitsphysicalandchemicalpropenies．Itaffectsthestrengthandloadbearingpropertiesofrocks．Theeasiestconventionalmethodofdeterminingmineralparticlesizeissieveanalysis，wheregrainsizeisseparatedonsieveofdifferentsizes／aperturesusingSieveShaker．Thustheparticlesizedistributionisdefinedintemsofdiscretesizerangesandmeasuredinmicron．Itisusuallydeterminedoveralistofsizerangesthatcoversnearlyallthesizespresentinthesample．Somemethodsofdeterminationallowmuchnarrowersizerangestobedefinedthatcanbeobtainedbyuseofsievesandareapplicabletopaniclesizesoutsidetherangeavailableinsieves．However，theideaofnotional‘sieve’that‘retains’particlesaboveacertainsizeand‘passes’paniclesbelowthatsizeisuniversallyusedinpresentingpaniclesizedistributiondataofallkinds．Thesizedistributionmaybeexpressedasa‘range’analysis，inwhichtheamountineachsizerangeislistedinorderoffinenessofparticles．Itmayalsobepresentedin‘cumulativeform’inwhichthetotalofallsizes‘retained’or‘passed’byasinglenotional‘sieve’isgivenforarangeofsizes．Rangeanalysisissuitablewhenaparticularidealmid—rangepaniclesizeisbeingsoughtwhilecumulativeanalysisisusedwheretheanlountof‘under-size’or‘over-size’mustbecontrolled．

2Materialsandmethod

TherocksamplesusedfortheinvestigationwereobtainedfromdifferentquarriesinNigeria．Dolomite，limestoneandmarblesampleswerecollectedfromEdoStateandgraniterocksamplesfromOndoState。

Nigeria．Fivebouldersofeachrocktypeofdimension90cm×

50cm×

50cmwererepresentativelyselectedfromrecentlyblastedportionoftherockswhichwerefteefromnaturaldefects，thatis,discontinuitiessuchascracks，joints，fracturesetcwerepackedproperlytoavoiddamageduringtransportation．Fortheunconfinedcompressivestrengthtest，therocksamplewascutintosquareshapewithdimensionof60mm×

60mmwithmasonrysawandVerniercaliperwasusedtomeasurethedimension．Also．forthepointloadtest，therocksampleswerebrokenintoirregularshapewithsledgehammer．Verniercaliperwasusedtomeasurethediameterandlengthofirregularshapedrocksamplesfromthedifferentlocations．Themeanvalueforlengthaddiameterwasdetemined。

TherocksampleswerepreparedandtestedinthelaboratorytoIntemationalSocietyforRockMechanicsStandardforeachstrengthtestcarriedoutusingMasonrySawMachineandCompressionTestingMachineandPointLoadTesterrespectively．Thereadingsweretakenandrecorded．ThesizereductionofequalweighedoftherocksampleswasdoneusingLaboratoryJawcrusherandtheparticlesizedistributionwascarriedoutinnotionalsetofsievesusingSieveShaker．Thecrushingtimesweretakenandrecordedandtheweightsofsamplesretainedonthesievesrecordedforsizedistribution．Therocksamplewerecutintosquareshapebyusingmasonrycuttingmachine，thecutsamplesweresmooth，freeofabruptirregularitiesandstrength．Fivespecimenofeachoftherocksamplesweretestedandthefailureloadwasrecordedforeachtestasthefailurewasobservedaxlallyinthecompressivetestingmachine．

SomelumpsofthedifferentrocktypeswerethencrushedusingtheLaboratoryJawcrusherandtakenrecordofthecrushingtimes．ThescreeningofthecrushedrocksampleswascarriedoutinasetofsieveusingtheLaboratorySieveShaker．Thesievewasarrangedintheorderofdecreasingapenure：

4700，2000，1700，1180，850，600，425，and212byplacingthesievethathasthelargestopeningatthetopandtheleastopeningatthebottom．Atightfittingpanorreceiverwasplacedbelowthebottomsievetoreceivethefinestgrainedwhichisreferredtoasundersize．Thecrushedsamplewasplacedonthetopsieveandalidwasusedtocoverittopreventescapeoftherocksampleduringmeprocess．Thesetofthesievewasthenplacedinasieveshakerwhichvibratesthesieveforproperscreening．Thisoperationwascarriedoutoneachoftherocksampleforfiveminutes．Thiswasachievedbyusingtheautomaticcontroltimerofthesieveshaker．Afterthescreeninganalysis，theretainedsampleoneachsievewasmeasuredonweighbalanceandrecordedtoth