采矿工程毕业设计（论文）-王庄煤矿3Mta新井设计

本科生毕业设计（论文）题目：王庄煤矿3.0Mt/a新井设计岩巷快速掘进现状和支护趋势姓名：学号：01120037班级：采矿工程（卓越工程师）2012-2班二〇一六年六月

中国矿业大学本科生毕业设计姓名：学号：01120037学院：矿业工程学院专业：采矿工程设计题目：王庄煤矿3.0Mt/a新井设计专题：岩巷快速掘进现状和支护趋指导教师：职称：讲师2016年6月徐州

中国矿业大学毕业设计任务书学院矿业工程学院专业年级采矿工程2012级学生姓名任务下达日期：2016年5月25日毕业设计日期：2016年3月25日至2012年6月10日毕业设计题目：王庄煤矿3.0Mt/a新井设计毕业设计专题题目：岩巷快速掘进现状和支护趋势毕业设计主要内容和要求：根据采矿工程专业毕业设计大纲，本毕业设计分为一般部分、专题部分和翻译部分，具体包括：1、一般部分：王庄煤矿3.0Mt/a新井设计，主要内容包括：矿井概况、矿井工作制度及设计生产能力、井田开拓、首采区设计、采煤方法、矿井运输提升、矿井通风系统等。2、专题部分：岩上的快速掘进技术现状和支护趋势。3、翻译部分：Samplingandanalysismethodformeasuringairbornecoaldustmassinmixtureswithlimestone(rock)dust院长签字：指导教师签字：

中国矿业大学毕业论文指导教师评阅书指导教师评语（①基础理论及基本技能的掌握；②独立解决实际问题的能力；③研究内容的理论依据和技术方法；④取得的主要成果及创新点；⑤工作态度及工作量；⑥总体评价及建议成绩；⑦存在问题；⑧是否同意答辩等）：成绩：指导教师签字：年月日

中国矿业大学毕业论文评阅教师评阅书评阅教师评语（①选题的意义；②基础理论及基本技能的掌握；③综合运用所学知识解决实际问题的能力；④工作量的大小；⑤取得的主要成果及创新点；⑥写作的规范程度；⑦总体评价及建议成绩；⑧存在问题；⑨是否同意答辩等）：成绩：评阅教师签字：年月日

中国矿业大学毕业论文答辩及综合成绩答辩情况提出问题回答问题答辩委员会评语及建议成绩：答辩委员会主任签字：年月日学院领导小组综合评定成绩：学院领导小组负责人：年月日摘要本设计包括三个部分：一般部分、专题部分和翻译部分。一般部分为王庄煤矿3.0Mt/a新井设计，共包括10章：1.矿区概述及井田地质特征；2.井田境界和储量；3、矿井工作制度及设计生产能力；4.井田开拓；5.准备方式；6.采煤方法；7.井下运输；8.矿井提升；9.矿井通风与安全；10.矿井基本技术经济指标。王庄煤矿位于山西省长治市郊区北部，交通便利。井田走向（南北）长约18.5km，倾向（东西）长约4.7km，井田总面积为80.5k。主采煤层为3#煤层，该煤层倾角平均为3°，平均厚度为5.17m。井田地质条件较为简单，其工业储量为562Mt，矿井可采储量392Mt，矿井设计年产量为3.0Mt/a，矿井服务年限为93a，矿井正常涌水量为144/h，最大涌水量为292/h。矿井绝对瓦斯涌出量为28.22/min相对瓦斯涌出量为3.23/t，为低瓦斯矿井。井田开拓方式为斜井两水平开拓。采用胶带输送机运煤，采用齿轨车进行辅助运输。矿井通风方式为中央并列式通风。而后转为分区域通风，矿井工作日为330d，工作制度为“四六”制。专题部分题目是岩巷快速施工现状和支护趋势翻译部分主要内容是关于松软厚煤层U型钢支护的技术改良，英文题目为：“Samplingandanalysismethodformeasuringairbornecoaldustmassinmixtureswithlimestone(rock)dust”。关键词：煤粉质量；浮沉；等速取样；低温灰化；岩尘

ABSTRACTThisdesignincludesthreeparts:thegeneralpart,thespecialsubjectpartandthetranslationpart.Thegeneralpartisanewdesignof3.0Mt/aforWhangZhuangmine,itincludestenchapters:1.Anoutlineoftheminefieldgeology;2.Boundaryandthereservesofmine;3.Theservicelifeandworkingsystemofmine;4.developmentengineeringofcoalfield;5.Thelayoutofpanelen;6.Theminingmethodusedinthiscoalmine;7.Transportationoftheunderground;8.Theliftingofthemine;9.Theventilationandthesafetyoperationofthemine;10.Thebasiceconomicandtechnicalnorms.WhangZhangminelinesinNorthofChangzicityinShangXiprovince.Thetrafficofroadandrailwayisveryconveniencetothemine.Therunoftheminefieldis18.5km,thewidthisabout4.7km，wellfarmlandtotalareais80.5km2.Thethreeisthemaincoalseam,anditsdipangleis4degree.Thethicknessofthemineisabout5.17minall.Geologicstructureofcoalfieldissimple,theprovedreservesoftheminefieldare562milliontons,andtherecoverablereservesare392milliontons.Thedesignedproductivecapacityis3.0milliontonspercentyear,andtheservicelifeofthemineis93years.Thenormalflowofthemineis144m3percenthourandthemaxflowofthemineis292m3percenthour.Therelativeminegasgushis3.23m3/tandtheabsolutegushis28.22m3/min,soitisalowgasmine.Themineisbeendividedintotwolevelstodevelopwithinclinedshaft.ThecentrallanewayusesBeltConveyortotransitcoal,andgearcarareusedforaccessorialtransportationintheroadway.Theventilationmodeofthismineiscenterjuxtaposeforminprophase.Andthenwillconvertedintoareaventilation.The“four-six”workingsystemisusedintheWhangZhuangmine.Itproducesfor330daysayear.Thetopicofspecialsubjectpartstrytoanalysisthemechanismofroadsidesupport

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process.TranslationpartisaboattheImprovementoftheU-shapedsteelsetsforsupporting.TheEnglishtitleis“Samplingandanalysismethodformeasuringairbornecoaldustmassinmixtureswithlimestone(rock)dust”.Keywords:Coaldustmass;floatdust;isokineticsampling;lowtemperature;ashing;rockdust目录TOC\o"1-3"\h\u一般部分1矿区概述及井田地质特征 页JournalofOccupationalandEnvironmentalHygieneISSN:1545-9624(Print)1545-9632(Online)JournalHomepage:/loi/uoeh20Samplingandanalysismethodformeasuringairbornecoaldustmassinmixtureswithlimestone(rock)dustT.L.Barone,J.R.Patts,S.J.Janisko,J.F.Colinet,L.D.Patts,T.W.Beck&S.E.MischlerTocitethisarticle:T.L.Barone,J.R.Patts,S.J.Janisko,J.F.Colinet,L.D.Patts,T.W.Beck&S.E.Mischler(2016)Samplingandanalysismethodformeasuringairbornecoaldustmassinmixtureswithlimestone(rock)dust,JournalofOccupationalandEnvironmentalHygiene,13:4,284-292,DOI:10.1080/15459624.2015.1116694Tolinktothisarticle:/10.1080/15459624.2015.1116694Acceptedauthorversionpostedonline:30Nov2015.Publishedonline:24Feb2016.SubmityourarticletothisjournalArticleviews:135ViewrelatedarticlesViewCrossmarkdataFullTerms&Conditionsofaccessandusecanbefoundat/action/journalInformation?journalCode=uoeh20Downloadby:[ChinaUniversityofMiningTechnology]Date:03April2016,At:05:05Samplingandanalysismethodformeasuringairbornecoaldustmassinmixtureswithlimestone(rock)dustT.L.Barone,J.R.Patts,S.J.Janisko,J.F.Colinet,L.D.Patts,T.W.Beck,andS.E.MischlerNationalInstituteforOccupationalSafetyandHealth,PittsburghResearchLaboratory,Pittsburgh,PennsylvaniaABSTRACTAirbornecoaldustmassmeasurementsinundergroundbituminouscoalminescanbechallengedbythepresenceofairbornelimestonedust,whichisanincombustibledustappliedtopreventthepropagationofdustexplosions.Toaccuratelymeasurethecoalportionofthismixedairbornedust,theNationalInstituteforOccupationalSafetyandHealth(NIOSH)developedasamplingandanalysisprotocolthatusedastainlesssteelcassetteadaptedwithanisokineticinletandthelowtemperatureashing(LTA)analyticalmethod.TheMineSafetyandHealthAdministration(MSHA)routinelyutilizesthisLTAmethodtoquantifytheincombustiblecontentofbulkdustsamplescollectedfromtheroof,floor,andribsofminingentries.TheuseofthestainlesssteelcassettewithisokineticinletallowedNIOSHtoadopttheLTAmethodfortheanalysisofairbornedustsamples.Mixturesofknowncoalandlimestonedustmasseswerepreparedinthelaboratory,loadedintothestainlesssteelcassettes,andanalyzedtoassesstheaccuracyofthismethod.Coaldustmassmeasurementsdifferedfrompredictedvaluesbyanaverageof0.5%,0.2%,and0.1%forsamplescontaining20%,91%,and95%limestonedust,respectively.TheabilityofthismethodtoaccuratelyquantifythelaboratorysamplesconfirmedthevalidityofthismethodandallowedNIOSHtosuccessfullymeasurethecoalfractionofairbornedustsamplescollectedinanundergroundcoalmine.KEYWORDSCoaldustmass;floatdust;isokineticsampling;lowtemperature;ashing;rockdustIntroductionThelargestU.S.minedisasterinseveraldecadeswascausedbyamethaneignitionthattriggeredamassivecoaldustexplosion.[1]Whenmethaneignites,thepres-suregradientfromtheblastcandispersecoaldustfrommineentrysurfaces.Ifthedispersedconcentrationsareontheorderof100g/m3,adustexplosionmayensueandpropagatethroughthemine.[2,3]Suchmechanismsarepreventedbyapplyinganinertrockdustsothat80%incombustiblecontentismaintained.[4]Rockdustisappliedatminingfacesbyhandorbypneumatichoses.[5]Areasthatrequirelargerquantitiesofrockdustapplication,suchasreturnentries,arecoatedbytrickledusterswhichdisperserockdustdirectlyintothemineair.[6]Rockdustcanremainsuspendedseveralhundredfeetfromthesource.[7]Inaddition,depositedrockdustcanbere-entrainedinmineventilationairforvelocitiesexceedingthresholdfrictionvalues[8]orforlowervelocitiesduetoinstantaneousturbulentvelocityfluctuations.[9]Substantialamountsofairbornerockdustmaybepresentandmayconfoundcoaldustmassmeasurements.Airbornecoaldustmassmeasurementsareneededtoassesstheeffectivenessofcontroltechnologiesforreducingcombustibledusthazardsinundergroundmines.Controltechnologiessuchasscrubbersandwaterspraysaredevelopedtopreventcoaldustreleaseintomineair-ways,whichlessenscoaldustdepositionandaccumulationonminesurfaces.[10,11]Thisreducesthepotentialforahazardousdustexplosionandimprovesthesafetyofminersinadditiontotheprotectionprovidedbyrockdustingpractices.Dustcontroltechnologiesandrockdustingareoftenusedconcurrently,socontroltechnologiesneedtobeevaluatedinmineaircontainingrockdust.Becauserockdustisappliedinlargequantitiestomeetregulations,aselectivedirectmethodisneededtodifferentiatebetweenairbornecoaldustandrockdustmasses,andtotheauthorsknowledgenosuchmethodhasbeenpreviouslypublished.Directmeasurementsbasedonsizeclassificationcannotbeusedsincerockdustandcoaldustsizedistributionsoverlap.[7]Indirectmeasurementsthroughchemicalmassbalancemethodswouldbeneededwhenseveraloverlappingchemicalprofilesareinfluential;thispreviouslyhasbeenappliedtodetermineearth-metalrockdustcontributionstofine(<2.5µm)airborneparticulatemattermassesinanundergroundgoldmine.[12]Whenassessingthemassofexplosivesizerangecoaldust,particlesupto74µmaretargeted[13]becauselargerdiametersrequirerelativelyhighconcentrationsforignitionandarelesslikelytoinitiateanexplosion.[2,3,14]Sizedistributionsof 74µmairbornecoaldustarerarelymeasuredbecauseofchallengeswithsuper-micronaerosolsampling.[11]Inonestudy,airbornedustwascharacterizedbyisokineticsamplingandanalysisofparticlescollectedinacyclonegritpot.[11]Themeandiametermeasureddownstreamofalongwallshearerwas15–35µm,andthediameterbelowwhich90%ofthemassresidedrangedfrom33–372µmforthreeAustraliancoalmines.Samplesinthelongwallshearerstudywerenotaffectedbyrockdustbecausethesamplinglocationwasclosetothesource.However,fordustcontroltechnologyevaluations,samplesmustbecollecteddownwindofthelongwallandcontrol,inareastreatedwithrockdust.Inpreviousstudiesofdepositeddustsamples,interferencefromrockdustwaseliminatedbyacidleachingofthedustsamplesandanalyzingtheremainingcoaldustusingacoultercounterorsieve.[15–17]Themassmediandiameterofdepositedcoaldustinminereturnentrieswas122–172µm,andthemassfraction74µmwas27–38%for50bituminousU.S.coalmines.[16]Themassofairbornecoaldust74µminmineventilationreturnsisalsocon-foundedbythepresenceofrockdustandrequiresgreatermeasurementselectivitythandepositionsamplesduetothelowermassconcentrationsofairbornecoaldust.Gram-quantitydepositeddustsampleswereanalyzedforincombustiblecontentbylowtemperatureashing(LTA)[5,18,19]andacidleachingmethods.[16]Harrisetal.[20]comparedLTAmethodsthatpreservedlimestonewhilecombustingcoalbutdifferedbythermaltreatmenttimes.Rockandcoaldustmixtureswereheatedat515°Cfor2.5hrbytheMineSafetyandHealthAdministration(MSHA)NationalAirandDustLaboratory(NADL)atMt.Hope,WV[18]andfor20hrbytheNationalInstituteforOccupationalSafetyandHealth(NIOSH).[19]Inaddition,themethodsdifferedinmoistureremovalandsievingprotocols,butthesepreparationprocedureswerenotexpectedtoaffectincombustiblemasses.TheMSHANADLandNIOSHmeasurementshadgoodagreementwithanaverage2%differenceforsamplescollectedateightdifferentcoalmines.TheresultssuggestedthattheMSHANADLanalysisprovidedaccurateincombustiblemasscontentalthoughshorterheatingtimewasused.MSHANADLmeasurementsalsoagreedwithacid-leachedmasses(1–3%difference)forlow,medium,andhighvolatilecontentcoals.[16]ApplyingtheMSHANADLmethodtorelativelylowmassairbornedustsam-plesmayrequireimprovedmethodselectivity.MethodsIOMcassettescontaining40–500mgrockandcoaldustweretreatedbyLTAandweighedinahumidity-andtemperature-controlledchamberwithawide-resolutionmicrobalance(310gto0.1mg)todetermineincombustiblecontent.Homogeneoussampleincombustiblefractionswereusedtoestimatethemassofcoaldustinmixtureswithrockdust.Thecoaldustmassestimationmethodwasappliedtoairbornedustsamplesacquiredinanundergroundcoalminedownwindofascrubber.Theweighingproceduresandcoaldustmassestimationmethodsaredescribedinwhatfollows.DustcharacteristicsPittsburghpulverizedcoal(PPC)dust74µmwasusedforthemethodevaluation.Itisamid-rank(mediumvolatilematter;mediumash)bituminouscoal,whichmustbeminedwithadherencetodustexplosionregulationsduetothevolatilehydrocarboncontent.Rockdustusedfortheevaluationfollowedregulationspecifications.[27]Itconsistedofpulverizedlimestonewithatleast70%massinthe74µmsizerange(AlleghenyMineralCorp.,Kittanning,PA).Limestonedustistypicallyusedforexplosionmitigationsinceitiswidelyavailableandinexpensive.Coalandrockdustmixtureswith20%,91%,and95%(mass)rockdustwerepreparedusingapestleandmortar.LTAStainlesssteelIOMcassetteswerefittedwith25-mmbinder-freequartz-fiberfilters.Whenexposedtothe2lpmfieldsamplingflowrate,blankquartz-fiberfiltershousedintheIOMcassettesexperiencednegligiblemasslossrelativetotherangeofsamplemassesinthecur-rentstudy.Forastudyinvolvingsmallersamplemasses,thequartzfibermasslossshouldbemeasuredforastatisticallysignificantnumberofcassettesandquantified.TheIOMassemblieswereheatedinamufflefurnacefor2.5hrat515°Ctovaporizeorganicsbeforeloadingdustsamples.Afterdegreening,theassemblieswereequilibratedfor12hrinahumidity-(52%)andtemperature-controlled(23°C)chamberandwereweighedusinganOhausAP310microbalancewith310gcapacityand0.1-mgresolution(Parsippany,NJ).Homogeneousandmixedsampleswithmassesof40mgto500mgwereloadedbytransferringpowdersintotheIOMcassettewithaspatula.Theloadedcassetteswereweighedfollowinga1minresidencetimeinanelectrostaticdeionizerand1minsettlingtimeinthemicrobalance.Withlongerresidencetimeinthedeionizer,massresultsremainedthesamemostlikelybecausethemetalcassettereadilydis-chargedelectrostaticchargeaccumulation.Moisturewasremovedbyheatingat105°Cfor2hr.Drysampleswerere-weighedandmoisturecontentwasfoundtobenegligible.Sampleswererampedtoset-pointoverabout1.5hrandwereheatedinairat515°Cfor2.5hrinamufflefurnace.Thetemperature-timetreatmentofthesampleswasapproximatelythesameasintheMSHANADLanalysis.[18]Thesamplesinthecurrentstudyunderwentheating1hrlongerat105°C,buttherewasnegligiblechangeinmass,sothemethodsshouldbeequivalent.Inaddition,coaldustinthecurrentstudymayhavecontainedsmallerparticlessincesamplesweresievedtolessthan75µm,ratherthanlessthan841µmasdonebyMSHANADL.[20]Thepresenceofsmallersizedustinthecurrentstudywouldimproveashingandnothinderthemethod.However,2–25timessmallersamplemassesrequiredgreatermassmeasurementsensitivity.LTAsensitivitywasimprovedbygravimetricallyanalyzingsamplesinahumidity-andtemperature-controlledchamberandwithawide-resolutionmicrobalance(310gto0.1mg)asdescribedabove.Coalandrockdustmixtureswereevaluatedforincombustiblemassfraction.Thefollowingequationswereusedtocalculatethemassofcoaldustinthemixedsamples:MT=MC+MR(1)MI=FICMC+FIRMR(2)whereMTistotaldustmass,MCiscoaldustmass,MRisrockdustmass,MIisincombustibledustmass,FICistheincombustiblefractionofhomogeneouscoaldust,andFIRistheincombustiblefractionofhomogeneousrockdust.Inputting(1)into(2)givescoaldustmassbasedonmeasuredvalues:MC=（FIRMT−M）/（FIR−FIC）(3)Weighingmixedsamplesbeforeandafterheatingprovidedtotalandincombustibledustmasses.TheincombustiblefractionsofcoalandrockdustweredeterminedbyLTAofhomogeneoussamples.Thesolutionprovidedcoaldustmassinmixedsampleswithrockdust.Figure.TheIOMsampleradaptedwithanisokineticnozzle.Thestandardholderisingray,standardfiltercassetteinredandgold,O-ringsinbrown,threadedadapterinblack,andisokineticnozzleinblue.(top)Expandedand(bottom)assembledviews.IsokineticsamplerAsinpreviousundergroundmine,atmospheric,andpersonalsamplingstudies,isokineticsampling[28]waspursuedtorepresentativelycollecttotalairbornedust(e.g.,BarkerandHumphreys;[11]Weddingetal.;[29]Kennyetal.[30]).AnisokineticsamplewasobtainedbyadaptinganozzletotheinletofastainlesssteelIOMcassette.Thenozzlewasattachedusinga3-Dprintercon-structed,threadedadapterwithO-ringsealsatthenozzleoutlet,theIOMcassettetop,andthecassetteholderrim(Figure1).Theadapterwasconstructedusinga3-Dprinterwithacrylonitrilebutadienestyrenepolymer.ParticlelossesfromelectrostaticeffectswerepreventedbyoverlappingthestainlesssteelisokineticnozzleandtheinletofthestainlesssteelIOMcassette,sothattheaerosoltraversedtheconductivematerial.Thesamplerwasoperatedat2lpm,aflowratecompatiblewithintrinsicallysafepumpsforuseincoalmines.Theadapterswereleak-testedwithlessthan2%differenceinpost-samplerflowrates.Figure.Rockdustdepositsontheroof,ribs,andmineflooratafieldsamplinglocationinacontinuousminerairventilationreturn.Figure.Isokineticfieldsamplers(blue)downwindofadustscrubberinacontinuousminerreturn.ResultsanddiscussionLTAForthemethodevaluation,gravimetricmeasurementsofcoaldustmasswerecomparedwithestimatesusing(3).Estimationrequiredincombustiblefractionmeasurementsofhomogenouscoalandrockdust.Thiswasdeter-minedbyloadingIOMassemblieswithhomogenousPPCandlimestonedustandthermallytreatingthesamplesfollowingtheMSHANADLprotocol.Theincombustiblefractionisthusmethod-specificandisnotacertifiedvalueforthematerial.Sincethehomogenousandmixedsamplesundergothetemperature-timehistory,theincombustiblefractionsshouldbeconsistent.HomogeneousPPCdustincombustiblecontentwasfoundtobe8.2%±0.6%byLTA.fractionwasmeasuredbythermogravimetricanalysis(TGA).AQ500TGA(TAInstruments,Inc.)wasusedtoheatthesamples20°C/min,andincombustiblecon-tentwasdeterminedfromtheTGAprofile.ResultsareshowninFigure4a,inwhichthemassfractionwasstableat8.05%—-avaluewithinour95%confidenceintervals.Limestonedustincombustiblecontentwas99.1%±0.2%,whichisconsistentwiththeQ500TGAprofilevalueat515°C(99.48%,Figure4b).AnexactcomparisonwasnotintendedsincetheQ500TGAhadarelativelyfastrampingtime(20°/min).Inadditiontohomogenousincombustiblefractions,mixturetotalmassandmixtureincombustiblemassarerequiredfor.Mixtureswith20%,91%,and95%rockdustwerepreparedbypestleandmortar,loadedinIOMassemblies,andgravimetricallyanalyzedtodeterminetotalmass.Mixtureincombustiblemasswasdeterminedbyweighingafterthermaltreatment.Withtheabovemeasurements,coaldustmasscouldbeestimatedusing.Coaldustmassestimateswereveryclosetoactualval-uesasshowninFigure5.Fortotaldustsamplesthatrangedfrom40–500mg,theaveragedifferencebetweenestimatedandactualcoaldustmassesaregiveninTable1for20%,91%,and95%rockdust.Estimatedvalueswereslightlylowerthanactualcoaldustmasses,asexpectedfromtheincombustiblecontentresults.AsshowninTable1,alldifferenceswerelessthan1%including95%confidenceintervals.Thus,themethodprovidedanaccurateestimateofcoaldustmassinmixtureswithrockdustandwassensitiveforhighrockdustfractions.Figure.TGAprofileinairmeasuredbyQ(TAInstruments)for(a)Pittsburghpulverizedcoaldustand(b)limestonedust.Therateoftemperatureincreasewas°perminute.Togetacomplimentarymeasurementusinganalternativemethod,theincombustiblefractionwasmeasuredbythermogravimetricanalysis(TGA).AQ500TGA(TAInstruments,Inc.)wasusedtoheatthesamples20°C/min,andincombustiblecon-tentwasdeterminedfromtheTGAprofile.ResultsareshowninFigure4a,inwhichthemassfractionwasstableat8.05%—-avaluewithinour95%confidenceintervals.Limestonedustincombustiblecontentwas99.1%±0.2%,whichisconsistentwiththeQ500TGAprofilevalueat515°C(99.48%,Figure4b).AnexactcomparisonwasnotintendedsincetheQ500TGAhadarelativelyfastrampingtime(20°/min).Figure.ComparisonofactualcoaldustmassloadedinIOMcassettetoestimatedmassusingEquation().Estimates(datapoints)aresimilartoactualvalues(lines);percentagedifferenceanderroraregiveninTable.Table.Percentagedifferencebetweenactualandestimateddustmasses.Massfractionrockdust20%91%Incombustibledust0.5(0.9)0.2(0.1)Coaldust0.2(0.4)0.06(0.07)Notes:%confidenceintervalsgiveninparentheses.TheselaboratoryresultssuggestedthatLTAofIOMsamplescouldbeusedtoassessairbornecoaldustconcentrationsinminesapplyingpulverizedlimestonedustforexplosionprevention.TheLTAmethodforsurfacedepositswaseffectivelyextendedtorelativelylow-massairbornedustsamplesbecause(1)theIOMcassettemasswaslowenoughtoprovidegooddustmassresolution,(2)cassettewalldepositswereincludedintheanalysis,(3)dustwassampledandanalyzedinthesamevesseltoavoidtransferlosses,and(4)samplesweregravimetricallyanalyzedinahumidity-andtemperature-controlledchamberwithawide-resolutionmicrobalance.FieldsamplingTheresultssuggestthattherockdustcorrectionmethodcanbeusedtoassessairbornecoaldustmassforcontroltechnologyevaluations.Themethodcanbeappliedinminesthatusepulverizedlimestoneforrockdustingandinwhichrockdustingcanbesuspendedduringthedesiredsamplingperiods.ConclusionsRockdustingisrequiredinallundergroundbituminouscoalminesintheU.S.forexplosionprevention.NIOSHconductedairbornedustsamplinginanundergroundcoalminetoassesstheperformanceofadustscrubber,butasignificantfractionofrockdustwaspresentinairbornedustsamplesduetosurfacere-entrainment.Thefractionincreasedwhenacoaldustscrubberwasemployed,soasensitivemethodwasrequiredtodifferentiatebetweenrockandcoaldustmasses.TheMSHANADLLTAmethodusedforgram-quantitysurfacesampleswasextendedtoairbornedustsamplesbygravimetricanalysisinahumidity-andtemperature-controlledchamberwithawide-resolutionmicrobalance.SamplelossesandhandlingerrorswereavoidedbycollectingandanalyzingdustinthesamevesselusinganIOMcassettewithquartz-fiberfilter.Coaldustmasswasdeterminedbymeasuringtheincombustiblefractionsofhomogeneousrockandcoaldust,thetotaldustmass,andtheincom-bustibledustmassafterthermaltreatmentbyLTA.Including95%confidenceintervals,thedifferencebetweenactualcoaldustmassandthatestimatedusingwaslessthan1%forrockdustfractionsupto95%.Thelaboratory-derivedmethodenabledaccuratedeterminationofcoaldustmassinthepresenceofrockdust.Thefractionsofrockdustevaluatedinthelaboratorywereconsistentwithvaluesfounddownwindofascrubberinacontinuousminerreturn.Themethoddescribedheremadepossibleassessingairbornecoaldustconcentrationsinthefieldsothataprototypecontroltechnologycouldbeevaluated.AcknowledgmentTheauthorsthankJohnSolesoftheOfficeofMineSafetyandHealthResearchfordustanalysisbytheQ500TGA.DisclaimerThefindingsandconclusionsinthisarticlearethoseoftheauthorsanddonotnecessarilyrepresenttheviewsoftheNationalInstituteforOccupationalSafetyandHealth(NIOSH).Mentionofanycompanyname,productorsoftwaredoesnotconstituteendorsementbyNIOSH.ReferencesMineSafetyandHealthAdministration(MSHA):“FatalAccidentReport.”Availableathttp://www.msha.gov/Fatals/2010/UBB/PerformanceCoalUBB.asp(accessedDecember,2014).Hertzberg,M.,andCashdollarK.L.:IntroductiontoDustExplosions.InIndustrialDustExplosions,K.L.Cashdollar,andM.Hertzberg(eds.).Philadelphia,PA:AmericanSocietyforTestingandMaterials,1987.pp.5–32.U.S.DepartmentoftheInterior:ElectronMicroscopyStudiesofExplosionandFireResidues,D.L.Ng,K.L.Cash-dollar,M.Hertzberg,andC.P.Lazzara(NTIS#PB83–250886),U.S.BureauofMines,1983.“MaintenanceofIncombustibleContentofRockDust,”CodeofFederalRegulationsTitle30,Part75.403.2010.p.495.Rokdok:“TheUseofStoneDusttoControlCoalDustExplosions:AReviewofInternationalPractice,March2003,”byP.Cain,Rokdok,Lethbridge,AB,Canada.ROHMAC,Inc.:MeteringandDistributionImprovementstoIncreasetheEffectivenessandEfficiencyofRockdusters,Mt.Storm,WestVirginia:ROHMAC,Inc.U.S.DepartmentoftheInterior:DustDepositioninCoalMineAirways,W.G.Courtney,J.Kost,andJ.Colinet.(NTIS#PB82–194853).U.S.BureauofMines,1982.Braaten,D.A.:Windtunnelexperimentsoflargeparticlereentrainmentdepositionanddevelopmentoflargeparticlescalingparameters.AerosolSci.Technol.21(2):157–169(1994).HarrisA.R.,andDavid