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1、煤矿科技英语——5.BRIEFINTRODUCTIONTOCOALMINING2006年8月1日11:50:0 Coalmining[1]istheremovalofcoalfromtheground.Theminingmethodemployedtoextractthecoaldependsonthefollowingcriteria:a.seamthickness[2],b.theoverburdenthickness,c.theeaseofremovaloftheoverburden,d.theeasewithwhichashaft[3]canbesunktore
2、achthecoalseam,e.theamountofcoalextractedrelativetotheamountthatcannotberemoved,andf.themarketdemandforthecoal.Thetwotypesofminingmethodsaresurfacemining[4]andundergroundmining[5].Insurfacemining,thelayersofrockorsoiloverlyingacoalseamarefirstremovedafterwhichthecoalisextractedfromtheexpos
3、edseam.Inundergroundmining,ashaftisdugtoreachthecoalseam.Currently,undergroundminingaccountsforapproximately60percentoftheworldrecoveryofcoal.5-1SurfaceMiningSurfaceminingisusedtoreachcoalreservesthataretooshallowtobereachedbyotherminingmethods.Typesofsurfaceminingincludeopen-pitmining[6],
4、driftmining[7],slopemining[8],contourmining[9],andaugermining[10].A.Open-pitMiningInopen-pitmining,orstripmining,earth-movingequipmentisusedtoremovetherockyoverburdenandthenhugemechanicalshovels[11]scoop[12]coalupfromtheunderlyingdeposit.Themoderncoalindustryhasdevelopedsomeofthelargestind
5、ustrialequipmentevermade,includingshovelscapableofholding290metrictonsofcoal.Toreachthecoal,bulldozers[13]clearthevegetationandsoil.Dependingonthehardnessanddepthoftheexposedsedimentaryrocks,theserockylayersmaybeshatteredwithexplosives.Todothis,workersdrillblastholes[14]intotheoverlyingsed
6、imentaryrock,filltheseholeswithexplosives[15],andthenblasttheoverburdentofracturetherock.Oncethebrokenrockisremoved,coalisshoveledfromtheunderlyingdepositintogiantearth-movingtrucks[16]fortransport[17].B.DriftMiningDriftminingisusedwhenahorizontalseam[18]ofcoalemergesatthesurfaceonthesideo
7、fahillormountain,andtheopening[19]intotheminecanbemadedirectlyintothecoalseam.Thistypeofminingisgenerallytheeasiestandmosteconomicaltypebecauseexcavationthroughrockisnotnecessary.Ifcoalisavailableinthismanner,itislikelytobemined.C.SlopeMiningSlopeminingoccursw
