采煤机外文翻译.docx

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英文原文

HighProductivity----AQuestionOfShearerLoaderCuttingSequences

K.Nienhaus,A.K.Bayer&H.Haut,AachenUniversityofTechnology,GER

1.Abstract

Recently,thefocusinundergroundlongwallcoalmininghasbeenonincreasingtheinstalledmotorpowerofshearerloadersandarmoredfaceconveyors（AFC）,moresophisticatedsupportcontrolsystemsandlongerfacelength,inordertoreducecostsandachievehigherproductivity.Theseeffortshaveresultedinhigheroutputandpreviouslyunseenfaceadvancerates.Thetrendtowards“biggerandbetter”equipmentandlayoutschemes,however,israpidlynearingthelimitationsoftechnicalandeconomicalfeasibility.Torealizefurtherproductivityincreases,organizationalchangesoflongwallminingprocedureslooksliketheonlyreasonableanswer.Thebenefitsofopti-misedshearersequences,leadingtobetterperformance,arediscussedinthispaper.

2.Introductions

Traditionally,inundergroundlongwallminingoperations,shearerloadersproducecoalusingeitheroneofthefollowingcuttingsequences:

uni-directionalorbi-directionalcycles.Besidesthesepre-dominantmethods,alternativeminingcycleshavealsobeendevelopedandsuccessfullyappliedinundergroundhardcoalminesallovertheworld.Thehalf-webcuttingcyclease.g.utilizedinRAGCoalInternational’sTwentymileMineinColorado,USA,andthe“Opti-Cycle”ofMatla’sSouthAfricanshortwalloperationmustbementionedinthiscontext.Othermineshavealsotestedsimilarbutmodifiedcuttingcyclesresultinginimprovedoutput,e.g.improvementsintermsofproductivityincreasesofupto40%arethoughtpossible.

Whereasthementionedminesareapplyingthealternativecuttingmethodsaccordingtotheirspe-cificconditions,e.g.seamheightorequipmentused,thispaperlookssystematicallyatthediffer-entmethodsfromageneralizedpointofview.Adetaileddescriptionoftheminingcycleforeachcuttingtechnique,includingtheillustrationsofproductivitveandnon-productivecycletimes,willbefollowedbyabriefpresentationoftheperformedproductioncapacitycalculationandasummaryofthetechnicalrestrictionsofeachsystem.Standardisedequipmentclassesfordifferentseamheightsaredefined,afterthemostsuitalbleandmostproductiveminingequipmentforeachclassareselected.BesidesthetechnicalparametersoftheshearerloaderandtheAFC,thelengthofthelong-wallfaceandthespecificcuttingenergyofthecoalarethemainvariablesforeachheightclassinthemodel.Asaresultofthecapacitycalculations,thedifferentshearercuttingmethodscanbegraphicallycomparedinastandartdisedwayshowingtheproductivityofeachmethod.Duetothegeneralcharacterofthemodelpotentialoptimizations（resultingfromchangesinthecuttingcycleandthebenefitsintermsofhigherproductivityoftheminingoperation）canbederived.

3.State-of-the-artofshearerloadercuttingsequences

Thequestion“Whyaredifferentcuttingsequencesappliedinlongwallmining?

”hastobeanswered,beforediscussingthesignificantcharacteristicsintermsofoperationalprocedures.Themajorconstraintsandreasonsfororagainstaspecialcuttingmethodaretheseamheightandhardnessofthecoal,thegeotechnicalparametersofthecoalseamandthegeologicalsettingofthemineinfluencingthecavingpropertiesaswellasthesubsidenceandespeciallythelengthofthelongwallface.Foreachminingenvironmenttheapplicationofeithersequenceresultsindifferentproductionratesandconsequentlyadvanceratesoftheface.ThecoalflowontotheAFCisanotherpointthatvariesliketheloadsontheshearerloader,especiallytherangingarmsandthestressesandthewearonthepicks.Athoroughanalysisisnecessarytochoosethebest-suitedminingcycle;therefore,generalsolutionsdonotguaranteeoptimalefficiencyandproductivity.

Acategorizationofshearerloadercuttingsequencesisrealizedbyfourmajorparameters.Firstly,onecanseparatebetweenminingmethods,whichminecoalintwodirections–meaningfromtheheadtothetailgateandonthereturnrunaswell–orinonedirectiononly.Secondly,thewaytheminingsequencedealswiththesituationatthefaceends,toadvancefacelineafterextractingtheequivalentofacuttingweb,isacharacteristicparameterforeachseparatemethod.Thenecessarytraveldistancewhilesumpingvariesbetweenthesequences,asdoesthetimeneededtoper-formthistask,too.Anotheraspectdefiningthesequencesistheproportionofthewebcuttingcoalperrun.Whereastraditionallythefullwebwasused,theintroductionsomodernAFCandroofsupportautomationcontrolsystemsallowsforefficientoperationsusinghalfwebmethods.Theforthparameteridentifyingstateoftheartshearerloadercuttingsequencesistheopeningcreatedperrun.Otherthanthepartialorhalf-openingmethodlikethoseusedinMatla’s“Opti-Cycle”,thecuttingheightisequaltothecompleteseamheightincludingpartingsandsofthangingorfootwallmaterial.

Bi-directionalcuttingsequence

Thebi-directionalcuttingsequence,ischaracterizedbytwosumpingoperationsatthefaceendsinacompletecycle,whichisaccomplishedduringboththeforwardandreturntrip.Thewholelongwallfaceadvanceseachcompletecycleattheequivalentoftwowebdistancesbythecompletionofeachcycle.Theleadingdrumoftheshearercutstheupperpartoftheseamwhilethereardrumcutsthebottomcoalandcleansthefloorcoal.Themaindisadvantagesofthiscuttingmethodarethoughttobetheunproductivetimeresultingfromthefaceendactivitiesandthecomplexoperation.Therefore,thetrendinrecentyearswastoincreasefacelengthtoreducetherelativeimpactofsumpinginfavouroflongerproductiontime.

Uni-directionalcuttingsequence

Incontrasttothebi-directionalmethod,theshearerloadercutsthecoalinonesingledirectionwheninuni-directionalmode.Onthereturntrip,thefloorcoalisloadedandtheflooritselfcleaned.Theshearerhaulagespeedsonthereturntripsarerestrictedonlybytheoperators’movementthroughthelongwallface,orthehaulagemotorsinafullyautomatedoperation.Thesumpingprocedurestartsinneartheheadgate.Thelowmachineutilizationbecauseofcuttingjustonewebpercycleisthemaindisadvantageoftheuni-directionalcuttingsequence.Besidesthecoalflowcanbequiteirregulardependingonthepositionoftheshearerinthecycle.

Halfwebcuttingsequence

Themainbenefitofhalfwebcuttingsequencesisthereductionofunproductivetimesintheminingcycle,whichresultsinhighmachineutilization.Thisisachievedbycuttingonlyahalfwebinmidfacewithbi-directionalgatesequences.Thefullwebisminedatthefaceends,withlowerspeedsallowingfastersheareroperationinbothdirectionsinmidseam.Besidetherealizationofhigherhaulagespeeds,thecoalflowontheAFCismorebalancedforshearerloadertripsinbothdirections.

Half-partial-openingcuttingsequence

Theadvantageofthehalformoreprecisely,partial–openingcuttingsequenceisthefactthatthefaceisextractedintwopasses.Figure2bshowsthattheupperandmiddlepartoftheseamiscutduringthepasstowardsthetailgate.Whereasthelastpartofthistripfortheequivalentofamachinelengththeleadingdrumisraisedtocuttherooftoallowtheroofsupporttobeadvanced.Onthereturntripthebottomcoalisminedwiththeadvantageofafreefaceandasmallerproportionoftheleadingdrumcuttingcoal;consequentlyleadingtolessrestrictionsofthehaulagespeedduetothespecificcuttingenergyofthematerial.Theshearersumpsinmidseamneartheheadgatetothefullwebwithoutinvokingunproductivecycletime.Likeforthetripthetailgatetheleadingdrumhastobeloweredamachinelengthaheadofthemaingate.

4.Productioncapacitycalculations

Atheoreticalcomparisonoftheproductivitybetweendifferentminingmethodsingeneral,orinthiscasebetweendifferentshearerloadercuttingcycles,isalwaysbasedonnumerousassumptionsandtechnicalandgeologicalrestrictions.Asaresult,thisproductioncapacitycalculationdoesnotclaimtoofferexactresults,althoughitdoesindicateproductivitytrendsandcertainparametersforeachanalyzedmethod.

Themodelworkswithso-calledheightclassesvaryingtheseamthicknessesbetween2mand5minstepsof50cm.Equipmentisassignedtoeachclass,havingbeenselectedbylookingatthebest-suitedtechnicalpropertiesavailableonthemarket.Apartfromthedefinedequipment,itisassumedthattheseamisflatandnoundulationsorgeologicalfaultsoccur.Inthemodel,theventilationandtheroofsupportsystemrepresentnorestrictionstotheproduction.Sincetheaimofthismodelistoshowwaystofurtherincreasesinlongwallproductivity,thecalculationisbasedonafullyautomatedsystemwithnomanualoperatorsrequiredattheface.ThehaulagespeedofthesheareristhereforeonlyrestrictedbythatAFCcapacity,thecuttingmotorsandthehaulagemotorsrespectively.

Thevariableparametersinthiscomparisonofthefourcuttingsequencesare,thespecificcuttingenergyofthecoaltobecutandthelengthofthelongwallface.Theformervaryingbetween0.2and0.4

thelatterbetween100mand400min50mintervals.The100mshortwallsweredeliberatelyselected,sincetheyarecomingmoreintofocusforvariousreasons.Geotechnicalaspects,likee.g.thecavingabilityofthehangingwallandfaults,restrictlong-wallpanelsinmanyplacestomaximumfacelengthsof150morless,likeinSouthAfricaandGreatBritain.Forthisreason,adetailedanalysisofthepotentialofsuch