浅析煤自燃火灾的原因、预报技术

1附录：外文资料与中文翻译外文资料：Analysisofthespontaneouscombustionofcoalcauseofthefire,forecastingtechniquesandpreventionmeasures1IntroductionMinefireisthemajornaturaldisastersincoalmines.SpontaneouscombustionofcoalisthemainformoftheminefireinChina'sstate-ownedkeycoalmines,morethan56percentoftheminethereisthedangerofspontaneouscombustion,firescausedbyspontaneouscombustionofcoalaccountedformorethan90%ofthetotalnumberofminefires[1].Inrecentyears,mechanizedminingthetopcoalcavingtechnologyhasbeenvigorouslypromotionandapplicationofasubstantialincreaseincoalproductionefficiency,butthecavingheightandlarge,leftoverfromthegoafresidualcoal,seriousairleakage,makingthemineofcoalspontaneouscombustiontooccurfrequently，hasbecomeoneofthemainfactorsrestrictingtheminesafetyinproductionandfurtherdevelopment[2].DistrictofXinjiang,Ningxia,InnerMongolia,thereisstillalargeareaofthecoalfieldfires,burningcoalamount1000-1360tonsperyear,theeconomiclossesofmorethan20billionyuan[3-4].SpontaneouscombustionofcoalproducesalargenumberofSO2,H2S,COandCO2gas,theseriouspollutionoftheenvironment;2coalfieldfiresalsocausedalargeareaofdamagetovegetation,soildesertification.2SpontaneouscombustionofcoalcauseanalysisCoallargelybytheorganicandinorganiccomponents,themaincombustibleelementscarbon(about65%~95%),followedbyhydrogen(about1%to2%),andcontainingasmallamountofoxygen(about3%to5%,sometimesupto25%),sulfur(about10%),theaboveelementstogetherconstitutethecombustiblecompounds,knownasthecombustiblematterofcoal.Inaddition,coalalsocontainssomenon-combustiblemineralash(5%to15%,alsoupto50%)andwater(generallybetween2%to20%change),thesesubstancesiscalledainertingofcoalnature.Coalbytheoxygenintheairoxidationistherootcauseofthespontaneouscombustionofcoal.Carbon,hydrogenandotherelementsinthecoaloccursatroomtemperature,thereactionofthecombustibleCO,CH4,andotheralkanessubstances.Oxidationofcoalisanexothermicreaction,iftheheatcannotbedissipated,willenablethecoalaccumulationoftemperature,inturn,acceleratetheoxidationofcoalandemitmoreofthecombustiblemassandheat.Whentheheatbuildup,thetemperaturerisestoacertainvalue,willcausecombustiblematerialcombustion,spontaneouscombustion.Coalspontaneouscombustionatthesametimehavethefollowingfourconditions:(1)Hasatendencyofspontaneouscombustion.Thespontaneous3combustiontendencyofcoalisanaturalpropertyofcoal,reflectingthebasicconditionsofthecoalmetamorphicgrade,moisturecontent,ashcontent,sulfurcontent,particlesize,porosity,thermalconductivity,isthespontaneouscombustionofcoal.Oxidationofcoalatroomtemperaturemainlydependsonthevolatilecontent,thehigherthevolatilecontent,thestrongerthetendencyofspontaneouscombustion,spontaneouscombustiontimewillbeshortenedaccordingly.Accordingtotherelationshipbetweenthedegreeofoxidationandignitionpointofcoal,rawcoalsampleignitionpointandoxidizedcoalsamplesoftheignitionpointofdifferenceΔTtospeculatethatthespontaneouscombustiontendencyofcoal.Ingeneral,coal-likefirebelowandΔTlargeeasytospontaneouscombustionofcoal;ΔT40℃coalspontaneouscombustioncoal;ΔTof20℃coal(ligniteandlong-flamecoal)isnoteasyfromcoal-fired.ItcanbeseenfromTable1,fromlignitetoanthracite,theignitionpointisgettinghigherandhigher,thespontaneouscombustiontendencyismoreandmoreweak.(2)Oxygenconditions.Thecoalpileisexposedtoair,surfacecontactwiththeairfullpenetration,andtheairgapbetweenthecoaltothecoalpileinternaloxidationtocreatetheconditionsinternaltothecoalpile.Blockofcoalisgreaterthegreaterthegapbetweenthecoal,thebetteroxygenconditions.(3)Oxidationtime.Coalfromtheoxidationofthedevelopmenttospontaneouscombustionisaprocess,andtheoxidationtimetoachievespontaneouscombustionperiodmaybecometospontaneouscombustion.Suchaslong-flamecoalspontaneouscombustionstage1to3months,thegascoalof4to6months.4(4)Thermalstorageconditions.Coalgivesoffheatintheoxidationprocess,onlywhentheheatreleasedisgreaterthantheheatdissipatedinordertomaketheheatbuildup,temperaturerise,toreachignitionpointwouldbespontaneouscombustionofcoal.Inaddition,thecoalparticlesize,moisture,ash,compaction,ambienttemperature,humidityandotherfactorsmayaffectthespontaneouscombustionofcoal.Thefinerthegranularity,thegreaterthespecificsurfacearea,theoxidationreactionismoresevere,themoreliabletospontaneouscombustion.Ingeneral,thespontaneouscombustionofcoalmaygothroughwaterevaporation,oxidation,thespontaneouscombustioninthreestages.Coalmoisture,coalleachingcoalwithoxygeninthewater,topreventdirectcontactwiththeoxidationreaction,aslongasthewaterisnotlost,itwillnotaffectthequalityofthecoal;Furthermore,theevaporationofwaterconsumesalotofheat,coalmoisturethegreatertheevaporationofthelongerthisstagethetemperaturewasnosignificantincrease.Ash，themoredifficulttospontaneouscombustion.Coalheapcompactioncanreducethegapbetweenthecoal,reducingairinfiltrationcapacityofthecoals,weakeningtheoxygenconditions.Ambienttemperatureandhumiditywillaffectthecoalspontaneouscombustion,thehigherthetemperature,thegreaterthehumidity,theshorterthetimeofthespontaneouscombustionofcoal.3CoalSpontaneousCombustionPredictionCoalSpontaneousCombustionP