外文翻译--大型煤炭经营设备.doc

1第六章英文翻译英文原文：ChuteDesignInALargeCoalHandlingFacilityDavidCharlesMorganT.C.C.(Mech.Eng.)MEMNAcknowledgements:TheBionicResearchInstitute,ChuteDesignConference1991ThepapergivesabriefoverviewofcoalhandlingattheSyferfonteinMine,intheOverlandConveyorSystem,andinthestockyards.Thecriteriaforselectionofchutedesignarediscussed,anddesignalternativesevaluated.DavidCharlesMorganisProjectsManager(MaterialsHandling)withKeeveSteynInc.HeisamemberoftheInstituteofMaterialsHandling,andhaswideexperienceinbulkmaterialshandlingandinstallation.REQUIREMENTFORANEWMINESyferfonteinCollieryisanentirelynewopencastminesituatedatTrichardtintheEasternTransvaal.ThepurposeofthemineistosupplementthecoalsupplytoSasolIIandSasolIIIfactoriesatSecundaandwillproducecoalinconjunctionwithfourexistingminesintheSecundaarea.Whenfullyoperationaltheminewillsupplysome7milliontonsofcoalperannum.Thiscoalwillbeofahighergradethanthatproducedfromtheexistingminesandbytheminingmethodsemployed,willgenerateaproductwithamuchlowerfinescontent.Toensurecontinuityofproductqualitytothefactoriesitisnecessarytobothblendthenewminescoalwiththatoftheexistingundergroundminesandtohomogenizetheproducttoensureanevendistributionoffines.ThecontroloftheproductionoffinesonthenewmineandthetransportsystemshasbeenofparamountimportanceandstudiesconductedbySasolontheexistingsystemshavebeenutilisedinthedesignofthetransferpointsandthedesigncriteriaoftheconveyors.2MINEOPERATIONCoalisstripminedandtransportedtothecoalpreparationplantintruckswithcapacitiesofupto170tons.Theofminecoalisloadedintoahopperbelowgroundlevelintheprimarycrushingbuildingwhereitisextractedbymeansofanapronconveyor.-300mmMaterialisextractedbymeansofalivegrizzlyandtransportedbyconveyordirecttothesecondarycrushingplant.The+300mmmaterialistransportedviaasecondapronconveyortoajawcrusherwhereitisbrokendownto-300mmanddispatchedtothesecondarycrushingplant.Priortosecondarycrushingthe-100mmproductisscreenedoutandthecrushingby-passedwhilstoversizeisbrokendowntotherequired-100mmbymeansofarotarybreaker.Rockpresentintheproductatthispointisremovedbytherotarybreakeranddischargedbyconveyorontoawasterockpile.Thefinalproductnowplusfinesgeneratedintheminingandreductionprocessisdeliveredtoafinesscreeningplantwherethedesiredportionof-6.4mmproductisremovedfromthefinalproduct.Throughputofthemineissuchthatthehandlingsystemandplantiscapableofhandling2400ton/hourofR.O.Mcoal.Acircularstockpileactsasabufferbetweentheoverlandtransportationsystem,fromwhichcoalmaybeextractedat2000tonperhour.Tominimizedegradationen-routetheoverlandsystemhasbeenkeptto3conveyorsofwhichthefirstisaslowrunningcollectionconveyor.Oftheother2flights,havebeenselectedat8kmand12kmrespectivelytokeeptransferpointstoaminimumandbeltsaghasbeenrestrictedto1%tominimizedegradationofthecoalenroute.AsplitterbinatthefactorydistributescoaltoeithertheSasolIIorSasolIIIstockyards.ThenewsystematSecundaconsistsofanadditional2slewingstackersand2barrelreclaimers,togetherwithadistributionsystemtotheexistingstackersandareclaimsystemtothefactories.Despitekeepingthetransferpointstominimumatotalof30individualtransfers3occurfromtheR.O.M.intakehopperattheprimarycrushingbuildingtothestockpilesatSecunda.Carefuldesignofthetransferpointstokeepdegradationtoaminimumwasthereforequiteessential.Sasolspolicyisoneofconstantimprovementandintheprocessoffixingtheconceptuallayoutmanychangesoccurredbothonconceptandprocessrequirements.Thisinvolvedradicalchangesparticularlytothestockyardsystemfromthetimeofinitialconception.Thisallowedinnovativethoughttoattimescomplextransferstations.CHUTEDESIGNCONVEYORCHUTEWORKToachievetheobjectivesofSasolandthenecessitytokeepdegradationtoaminimumitwasnecessarytomoveawayfromconventionalchutes.Varioustypesoftransferwereinvestigated,cateringfromin-linededicateddischargethroughtomulti-dischargeandproportioningchutes.InvestigationswithSasolshowedthatthelowheadroomcurvedchutewithmovingheadformulti-dischargewastheidealandenquiriesanddesignswerebasedonthisconcept.Thespecificationforthechutesbeingasfollows:CHUTESPECIFICATIONTheeliminationofcoaldegradationinchutesisofparamountimportanceandthefollowingarefactorsinfluencingthedesignofdegradationfreechutes:Alargeconvexcurveofthetroughedbelttotheheadpulleycircumferenceensuringinherentlystablebeltandpayloadwiththeinitialtrajectorypointlyingt5outbyeofthetopdeadcentreoftheheadpulley.Suitablydesignedbelttransitionattheheadendensuringasmoothchangeofpayloadcrossofpayloadcrosssectionwithminimumsurfacelumpcoalmovement.Headpulleyoflargerdiameterthannecessarybybeltrequirementsensuringamorecompacttrajectory.Thecompactionpressureofthecoal,determinedfromitscriticalsuperficialmoisturelevelandupper,lowerandaveragesizedistribution,criticalindeterminingtheinitialslidingangleofthecoal.4Assuringthatthecoaldoesnotimpactonanysurfacebutlandsatalowangleofincidenceandthatfreefallisrestrictedto500mmmaximum.Preferablycoalshouldslideonthechuteforthegreatestpossiblelength.Thelargersizedcoalbecushionedbythefinesonlandinginthechute.Dischargeofthecoalontothefollowingbeltatanearmatchingspeedandinclinedat30topreventpossibledamagetothebeltbygouging,cuttingorpiercing.Allmainstreamtransferchutesaretoconsistofthefollowingsections.Afirstsectiontangenttothebottomfaceofthetrajectory,taperingfromheadchutewidthtochutedischargewidthandtransformingfromarectangularcrosssectiontoasemi-circularsectionwithupperverticalsidesandtop.Thetaperingsidestodeflectlooselumpsbacktothemaintrajectoryflow.Thelengthandangleofdeclineofthissectiontobedeterminedfromcoaldischargespeed.Asecondsectionofsemi-circularcrosssectionwithupperverticalsidesandtopat300and1mlongensuringthatthetopofthetrajectorymeetsthecoalalreadyslidinginthechuteataverylowangleofincidence.Forin-linetransfers,theremainingsection/stobeasforthesecondwithangleofdeclinedesignedtoensurematchingdischargecoalandreceivingbeltspeed