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BreathoffreshairWithnoaspectofundergroundminesafetymorefundamentalthanproperventilationvariousmodernsystemsarebeingusedtoensureairflowissafeforworkersBYBREEFREE__NWhenitcomestoundergroundmineworkingsfewthingsaremoreimportantthanadequateventilation.Everyyearenormouseffortsare__deto__intainandimproveairflowtoworkingareas.Thisistodiluteemissionsbelowstatutorylimitsrendertheairharmlesscarryawayhazardouscontaminantsandprovidene__ssarylevelsofoxygenfortheminers.Asaresultventilationsystemsformacrucialpanofthedesignofanyminethelayoutofwhichisdeterminedbytheorebodygeologylegislation__ailable__npowerminingmethodsandtheequipmentused.Specificenviro__entalissuessuchasvirginrocktemperaturesspontaneouscombustionanddustcontrolfurthercomplicatetheoreticalventilationsystems.Moreoverwhateversystemiseventuallyplannedwillinevitablysufferfromimperfectimplementationandcontrolbecauseoftheday-to-daycomplexitiesoftheextractionoperation.“Ventilationinthemodemmineisanessentialprerequisiteperhapsevenmoresothaninthepast.Apartfromtheobviousbiologicalaspectofpreventingdepletionofoxygenandthebuild-upofcarbondioxideintheairthemine-ventilationsystemmustbeabletokeepquantitiesofcontaminantsbelowharmfullevels”saysMikeBeareprincipalminingengineerforconsultancySRK.Heexplains:“Amodernminehas__nysour__sofharmfulsubstan__sincludingfumesfromexplosivesdustfrombrokenrockandgasespresentintherocksthemselves.inadditiontothesethemodemapproachtominingincludingtheuseof___sel-enginetrucksandloadersresultsinlargequantitiesofCOnitrousfumesand___sel-particulate__tterenteringthemineairflow.Whilescrubbersarefittedtheydonotremoveallthecontaminantsandtheventilationsystemhastobedesignedtobeabletodilutethesetosafelevels.”TheseissuesdemonstratetheneedforexpertdesignobservesSRKwhichalsosignalstheneedforventilationcoststobeminimisedinthesamewayasanyothercostaspectAsaresultvariousproductions__nariosneedtobeaddressedattheoutset.__ntraltoallofthesecalculationsisthe______factthatairflowisdeterminedbytemperatureandpressuredifferen__sairflowsfromhigh-pressuretolow-pressureareas.InamineItiscausedbypressuredifferen__sbetweentheintakeandexhaustopenings.Airflowfollowsasquare-lawrelationshipbetweenvolumeandpressure-inordertodoublethevolumeofairfourtimesthepressuremustbeexerted.CREATINGTHEPRESSURETherearetwo__intypesoffan:Axial:thesearegenerallyhigh-volumelow-pressurefanseitherdirectlydrivenbythemotorshaftwiththemotorinsidethetubebodyorremotelydrivenusingbeltswiththemotoroutsidethetubebody.Thesearegenerallyadjustableforvolumebysettingthepitchoftheadjustablebladesontherotorandinsomecasesmotorspeedcanbetailoredtoadjustvolumeandpressure.__ntrifugal:thesearegenerallyhigh-pressurelow-volumefansthatconsistofamulti-bladedsquirrel-cagewheelinwhichtheleadingedgeofthefanbladescurvestowardthedirectionofrotation.Thesefansh__elowspa__requirementslowtipspeedsandarerelativelyquiet.AUXILIARYVENTILATIONTheventilationofdead-endworkpla__sisthemostfrequentandImportantapplicationofauxiliaryventilation.Itisusedforbothdevelopmentandexplorationworkaswellasforproductionheadingswithonlyoneentran__.A__jorinconvenien__withanymethodofauxiliaryventilationduringdevelopmentisthene__ssityoffrequentextension.Theauxiliaryairstreammustbedeliveredasdosetothefa__aspossiblesothatitcansweepawayanyimpuritiesthath__ebeengenerated.Thetwo__inmethodsofventilatingthefa__sofdead-endworkpla__sareerectingline-bratti__airenteringononesideofthebratti__andreturningIntheothersideandtheinstallationofafancoupledwithventilationtubing.Thepracti__ofredirectingthe__inventilationsystemwith__allerlocalfansisusedwherealinebratti__isnotadequate.Tubingoftensuspendedfromtimbersorroofboltsifapprovedcarriestheairtoorawayfromtheworkingfa__tubingisrigidforexhaustsystemsandcollapsibleforforcingsystems.Thisauxiliaryventilationsystemallowscontinuousminerstooperatewithoutbeingobstructedbybratti__constructions.Inadditionboosterfanscanbelocatedinlongairwaystoboosttheairflowvolume.Thesefanscanbefree-standingandusedwithoutusingbulkheads.CIRCULATIONCONTROLSMine-ventilationsystemspresentauniquechallengeinthattheworkfa__sarenor__llymovingawayfromthesour__offreshair.Thisrequirescontinuouschangestotheventilationsystem.ThesecontrolsareneededtodistributetheairundergroundsothateachworkingsectionIsventilatedwithanadequatesupplyoffreshair.Thevariousdevi__sworkcollectivelytodirectthemovementoftheairthroughthe__inIntakestotheworkingsectionandmoveoutthroughthereturnswithoutshort-circuitingwhichoccurswhenairfromtheintakegoesdirectlyintothereturn.ELIMINATING___SELEMISSIONSAsMrBearcommentedabovereducingharmful___selemissionsisanothervitalaspectofimprovingundergroundworkingconditions.Butwhile___sel-engine__nufacturersand__chineOEMsshouldbeacknowledgedfortheircombinedachievements.Inreducingpollutantstherewouldalwaysbeaper__ntageofemissionsthatmustbestrictlymonitoreddilutedandventedtothesu_____.Whatisneededisanalternativeto___selandsomepeoplebelievefuel__llscouldbethekey.A2003studybytheUniversityofNevadauseddataobtainedfromasurveysentto173USmetalandnon-metalundergroundmines.Froma61%returnthesurveyincluded4786___selunitstotalling478200kWcollectivelyconsumingabout68MI/yof___selfuel.AsofJanuary20theMineSafetyandHealthAdministrationMSHAenactedaregulationlimitingtotalDPM___selparticulate__tteremissionsfrom___selenginestoanInterim450Ngmoftotalcarbon/cmofambientairandsuggesteditwouldberedu__dfurtherto160pgminJanuary
2008.Extensiveuseof___sel-poweredmobileequipmenthasresultedinthedevelopmentofminingmethodssuchasdriftandfillstopingwhichinmostcircumstan__srequire‘dead-end’auxiliaryventilationratherthanthrough-flowventilation.Sin__itcanbeharderandmoreexpensivetoventilatethesestopesandmeettheDPMregulationsmostmineswillh__etomodifytheiroperatingpracti__s.MinescanexploitincreasedventilationtohelpmeettheDPMcriteriabutthisinvolvesconsiderablecostssin__fanpowerIsproportionaltocubic-airquantityandpurchasingandinstallingfansisveryexpensive.Soperhapstheuseoftotalemission-free__chinesinourcoalminesIscloserthanwethink.井下通风在矿业安全的方面没有比合适的通风更重要,为了矿工的安全各种各样的先进系统被用于保证风流的通畅布利弗里曼的观点当谈到煤矿工作时,没有什么事比适当的通风更重要我们每年都要做很多工作来维护和改进工作空间的风流条件为了将放射物控制在一定浓度范围里,使空气清洁,使污染物受到控制,为矿工提供必需的新鲜空气通风系统成为所有矿设计的一个关键因素,与煤炭储量及地质条件、立法、可利用的人力资源、开采的方法和使用的设备等有关具体的环境问题如地温、自燃和粉尘等使通风系统进一步复杂化而且,不管什么系统最终由于渐渐复杂的操作都会不可避免地遭受不__的实施和控制“通风在煤矿是一个根本前提,这或许比从前更突出从生理方面说除了防止空气中氧气量的减少和二氧化碳积累外,矿井通风系统必须能维持污染物的数量在有害的水平之下”,__学校SRK主要采矿工程师麦克Beare说他解释说“一个现代矿井有许多危险源,包括由于爆破释放出的有害气体、生产过程中产生的粉尘和岩层本身释放的有毒气体除这些,还包括对于采矿过程中产生的大量的CO,亚硝烟和粉尘颗粒即使抽放系统合适,它们也不能去除所有污染物,所以通风系统必须被设计成能把这些污染物降低到安全水平”SRK发现这些问题提出了对专业设计的要求,同时也发出__需要将通风费用同其他费用一样降低到最小程度因此,各种生产状况在最初都要考虑到所有问题的核心是一个很简单的事实气流取决于气压差,气流从高压地区流向低压地区在煤矿上,它由井筒之间的压力差造成气流的风量和压差之间有一个二次方定律关系——为了使风量加倍,必须使压差增加四倍产生压差风机的二种主要类型轴向这些通常大风量,低风压的风机要么是被处在风机内部的电动机直接驱动要么是被处于风机外部的电动机通过皮带驱动风量可以通过调整叶片的角度来调整,并且调整电动机的转速也可以调整风机的风量和风压离心这些通常高压差,低风量风机是由多片叶轮和螺旋式机壳组成机壳的作用是吸集从叶轮中甩出的空气这类风机占用空间小,低转速并且是相对较安静辅助通风辅助通风系统的最频繁和最重要的作用是保证独头巷的通风,它应用于勘探和掘进,以及盲巷的生产过程中辅助通风系统的主要不便之处在于生产过程中需要不断的向前延伸辅助通风系统必须向尽头输送足够的风量,来保证空气的清洁向工作面通风主要有两个方法一是搭建临时建筑(风流从建筑的一边通过,从另一边返回),二是将局部通风机与风筒相连直接把风送到工作场所当主通风系统满足不了通风需要时,局部通风机被用来弥补这种不足风筒,通常布置在巷道的顶端,将新鲜风流送到工作面或将污风从工作面带走这个辅助通风系统能保证连续的生产,从而避免了因为搭建临时建筑而被迫停止生产的情况另外,局部通风机允许架设很长的通风路线而且这些局扇可以__使用二无需使用隔框循环控制煤矿通风系统所面临的一个特殊的问题是工作面通常渐渐远离新鲜空气的来源处,这就决定了通风系统也要连续的发生变化必须得采取措施来控制地下空气的流动从而来保证每个工作面都有充足的新鲜空气来供给所有设备共同运转来保证新鲜风流从进风井进入,通过工作面最后由回风井排出,而不出现风流从进风井进入后直接从回风井排出的短路现象发生防止柴油泄露Bear先生前面说过,减少有害的柴油泄露是改进地下工作环境的另一个重要方面但是,我们应该承认柴油引擎和机器制造者OEMs在减少污染物方面的成就为了减少污染物,必须确切地监测到泄露、稀释和释放到地面的百分比另一关键是选择对柴油,并且人民相信燃料电池可能能解决这个问题内华达大学的一项2003年的研究使用了173家美国金属和非金属地下矿勘测得到的数据61%的数据显示,调查__同消耗4786个柴油单位总计478200kW约合柴油68MI/y在1月20日,矿安全卫生管理MSHA在2008年1月制定了限制从柴油引擎泄露到空气中的DPM柴油粒状物质的量,建议从450Ngm进一步将减少到160pgm对柴油发动的流动设备的广泛的应用导致了采矿方法的发展,例如分层进路调顶崩矿采煤法和水平分层充填采矿法,在多数情况下,这都要求盲巷辅助通风而不是贯穿通风因为风流通过采空区,所以达到DPM的规定就更加的困难和昂贵,多数矿将必须修改他们的操作规程煤矿可以通过增加风量来帮助符合DPM标准,但是这需要花费大量的金钱,因为风扇能力与空气体积是成比例的,并且__和__风扇是非常昂贵的因此,我们认为或许在煤矿中使用无遗漏的机器更有可能实现PAGE6。