handout basting technique - 5 - lab mekbat upn veteran...
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RockBlastingTechniqu
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RockBlastingTechnique - I
By:Dr.Ir.SinggihSaptono,MT.Dr.Ir.S.Koesnaryo,M.Sc.
Dr.Ir.BarlianDwinagara,MT.Ir.R.Hariyanto,MT.
HANDOUT
MiningEngineeringDepartment– FacultyofTechnologyMineralUniversitasPembangunanNasionalVeteranYogyakarta
February,2016
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RockDrillingMethodLesson5
RockBlastingTechniqu
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tRockDrilling
• Rockdrilling,inthefieldofblasting,isthefirstoperation carriedoutanditspurposeistoOpenholes,withthe adequategeometryanddistributionwithintherockmasses,wheretheexplosivechargeswillbeplacedalongwiththeirinitiatingdevices.
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tThesystemsofrockdrillingthathavebeendeveloped andclassifiedaccordingtotheirorderofpresentday applicabilityare:
• -Mechanical:Percussion,rotary,rotary-percussion.• - Themzal:Flame,plasma,hotfluid,Freezing.• - Hydraulic:Jet,erosion,cavitation.• - Sonic:Highfrequencyvibration.• - Chemical:microblast,dissolution.• - Electrical:Electricarc,magneticinduction.• - Seismic:Laserray.• - Nuclear:Fusion,fission.
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TypesofDrillingOperationsUsed in RockBreakage
• Manualdrilling.Thisiscarried outwithlightequipment thatishandheldbythedrillers.Itisusedinsmall operationswhere,duetothesize,othermachinerycannotbeusedoritscostisnotjustified.
• Mechanizeddrilling.Thedrillingequipmentis mounteduponrigswithwhichtheOperatorcancontrolall drillingParametersfromacomfortableposition.These structuresorchasis canthemselvesbemountedonwheelsortracksandeitherbeself-propelledortowable.
RockBlastingTechniqu
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tThetypesofwork,insurfaceaswell asinundergroundoperations,canbeclassifiedinthe followingsgroups:
• Benchdrilling.Thisisthebestmethodforrock blastingasafreefaceisavailablefortheprojectionof materialanditallowsworkto besystemized. Itisusedinsurfaceprojectsaswellasinundergroundoperations,usuallywithverticalblastholes,although horizontalholescanbedrilledonoccasion.
• Drillingfordrifting andtunnelling.Aninitialcavity orcutmustbeopenedtowardswhichtherestofthe fragmentedrockfromtheotherchargesisdirected.Blastholedrillingcanbecarriedoutwithhandhelddrills,but thetrendistowardstotalmechanization,usingjumboswithoneorvariousbooms.
RockBlastingTechniqu
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t• Productiondrilling.Thistermisusedinmining operations,fundamentallyunderground,todescribethe laborsoforeextraction.Theequipmentandmethods usedvarywiththeexploitationsystems,havingthecommon factoroflittleavailablespaceinthedriftsforblastholedrilling.
• Drillingforraises.Inmanyundergroundandcivil engineeringprojectsitisnecessarytoOpenraises.Although thereisatendencytoapplytheRaiseBoringmethod,stilltodaythelongblastholemethodisusedas wellasotherspecialdrillingsystemscombinedwith blasting.
• Drillingrockswithoverburden.Thedrillingofrockmasseswhicharecoveredwithbedsofunconsolidatedmaterialscallsforspecialdrillingmethodswithcasing. Thismethodisalsousedinunderwateroperations.
• Rocksupports.Inmanyundergroundoperationsand sometimesinsurfaceonesitisnecessarytosupportthe rocksbymeansofboltingorcementingcables,inwhich drillingisthefirstphase.
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Fieldsof ApplicationforThe DifferentDrillingMethods
• Rotary-percussivemethods.Thesearethemostfrequentlyusedinalltypesofrocks,thetophammer aswell asthedown-the-holehammer.
• Rotarymethods.Thesearesubdividedintotwo groups,dependinguponifthepenetrationiscarried out bycrushing,withtricones orbycutwithdragbits.The firstsystemisusedinmediumtohardrocks,andthe secondinsoftrocks.
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RockPropertiesThatAffectDrilling
Theprincipalphysicalrockpropertiesthathaveinfluenceuponpenetrationmechanismsand,asaconsequence,on choiceofthedrillingmethodare:
1. Hardness,2. Strength,3. Elasticity,4. Plasticity,5. Abrasiveness,6. Texture,7. Structure,8. Characteristics ofbreakage.
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t1.Hardness• Hardnessisconsideredtobetheresistanceofasurface layertobepenetratedbyanotherbodyofharderconsistency.
• Inrock,itisafunctionofthehardnessandcompositionofitsmineralgrains,theporosity,degreeofhumidity, etc.
• Thehardnessofrocksistheprincipaltypeofresistance thatmustbeovercomeduringdrilling,becauseoncethe bithaspenetrated,therestoftheoperationiseasier.
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t2.Strength
Mechanicalstrengthofarockisthepropertyofopposingdestructionbyanexternalforce,eitherstaticordynamic.Therocksgivemaximumresistancetocompression,normally,asthetensilestrengthisnotmorethan10or 15%ofthecompressivestrength.Thisisduetothefragilityofrocks,tothelargequantityoflocaldefectsandirregularitiesthatexistandtothesmallcohesionbetween theparticlesofwhichtheyareconstituted.
RockBlastingTechniqu
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• Themajorityofrockmineralshaveanelastic-fragile behavior,whichobeystheLawofHooke,andaredestroyedwhenthestrainsexceedthelimitofelasticity.
• Dependinguponthenatureofdeformation,asfunction oftheStressesproducedbystaticcharges,threegroupsof rocksaretakenintoconsideration:1)Theelastic-fragile orthosewhichobeytheLawofHooke,2)Theplastic-fragile, thathaveplasticdeformationbeforedestruction,3)Thehighly-plasticorveryporous,inwhichtheelastic deformationisinsignificant.
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• Theplasticitydependsuponthemineralcomposition oftherocksanddiminisheswithanincreaseinquartz content,feldsparandotherhardminerals.Thehumid claysandsomehomogeneousrockshaveplasticproperties.
• Theplasticityofthestonyrocks(granites,schistoses,crystallines andsandstones)becomesnoticeable especiallyathightemperatures.
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5.Abrasiveness• Abrasivenessisthecapacityoftherockstowearawaythe contactsurfaceofanotherbodythatisharder,inthe rubbingorabrasiveprocessduringmovement.
• Thefactorsthatenhanceabrasivecapacitiesofrocks arethefollowing:a. Thehardnessofthegrainsoftherock.Therocks thatcontainquartzgrains
arehighlyabrasive.b. Theshapeofthegrains.Thosethatareangulararemoreabrasivethanthe
roundones.c. Thesizeofthegrains.d. Theporosityoftherock.Itgivesroughcontact surfaceswithlocalstress
concentrations.e. Theheterogeneity.Polymineral rocks,although theseareequallyhard,are
moreabrasivebecausethey leaveroughsurfaceswithhardgrainsas,forexarnple, quartzgrainsinagranite.
• Thispropertyhasgreatinfluenceuponthelifeofdrill steelandbits.
RockBlastingTechniqu
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t Themeanamounts ofquartzfordifferent typesofrockareindicated
RockBlastingTechniqu
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t6.Texture
• Thetextureofarockreferstothestructureofthegrainsof mineralsthatconstituteit.Thesizeofthegrainsarean indication,aswellastheirshape,porosityetc.Allthese aspectshavesignificativeinfluenceondrillingperformance.
• Whenthegrainshavealenticularshape,asinaschist, drillingismoredifficultthanwhentheyareround,asina sandstone.
• Thetypeofmaterialthatmakesuptherockmatrixand unitesthemineralgrainsalsohasanimportantinfluence.
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7.Structure
•Thestmctural propertiesoftherockmasses,suchas schistosity,beddingplanes,joints,diabases andfaults,as wellastheirdipandstrikeaffecttheallignment ofthe blastholes,thedrillingperformanceandthestabilityof theblasthole walls
RockBlastingTechniqu
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t Propertiesofrocktypesaccordingtoorigin-basedclassification.
1 MPa = 1 MN/m2= 10 kg/cm2 = 142.2 psi
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tClassificationoftherockmasses
RockBlastingTechniqu
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t RotaryPercussiveDrillingTophammer.Inthesedrills,twoofthebasicactions,rotationandpercussion,areproducedoutsidetheblasthole,andaretransmittedbytheshankadaptorandthe drill steeltothednll bit.Thehamrnerscanbedriven hydraulicallyorpneumatically.
Downtheholehammer.Thepercussionisdelivered directlytothedrillbit,whereastherotationisperformedoutsidethehole.Thepistonisdrivenpneumatically,whiletherotationcanbehydraulicorpneumatic.
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RockBlastingTechniqu
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tThemainadvantagesofrotarypercussivedrilling are:
• Itcanbeappliedtoanytypeofrock,fromsofttohard.
•Widerangeofdiameters;•Versatileequipment, itadaptswelltodifferentoperations andisveryMobile;
•OnlyrequiresoneOperator;•Easy,quickmaintenance,and•Thecapitalcostisnothigh
RockBlastingTechniqu
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tRotarypercussiondrillingisbaseduponthe
combination ofthefollowing:
• Percussion.Theimpactsproducedbyrepeated blowsofthepistongenerateshockwavesthataretransmitted tothebitthroughthedrillsteel(intopharnmer)or directlyuponit(downthehole).
• Rotation.Withthismovement, thebitisturnedso thattheimpactsareproducedontherockindifferent positions.
• Feed,orthrustload.Inordertomaintainthecontact ofthednll bitwiththerock,athrustloadorfeedforceis appliedtothedrillsiring.
• Flushing.Flushing removesthedrillcuttingsfrom theblasthole.
RockBlastingTechniqu
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t• Percussionoutputpowerinpercussivedrillingisproducedbytherock drill’simpactenergyandfrequency.
• Pneumaticdrillinghasatypical impactfrequencyofbetween1,600- 3,400hitsperminute;hydraulicdrilling,2,000- 4,500hitsper minute.
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PercussionDrillRigs
Percussiondrillcanbeair– orhydraulic– operatedandaregenerallylimitedtoholediameterof5inchesorless.
Percussiondrillusebuttonorcross(X-typedrillbitsinwhichthecuttingtoolismadeofhardtungstencarbide.Wingangleandbuttonconfigurationsaredesignedtoaccommodatesofttohardformationsandcomeinavarietyofconfigurations.
RockBlastingTechniqu
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t• DTHhammers,withthepistoninthehole,tendtodrillstraighterholesatgreaterdepthascomparedtoOTHdrifters.Theair-drivenpistonhammercausesthebittorapidlyimpacttherockwhilethebitisslowlyturned.DTHhammersareefficientinhard-rocktypes.Withthehammerinthehole,drill-pipevibrationsareeliminated
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t Steeltoothbitselection
• Softformationbits,TheTypeS,regularcirculationsteeltoothbitisdesigned foroptimumperformanceinformationsoflowcompressivestrength,suchassoftsandrock,calcite,shaleand clay.Theseformationsquiteoftencontainabrasivematerials suchassharpsandandmaybeinterspersedwith layersofmediumandhardformations.
• Mediumformationbits,TheTypeMandregularcirculationsteeltoothrackbits aredesignedforabrasiveandnon-abrasivemediumformations. Notethatthisdesigndiffersfromthe“softer” typesprincipallyintheprogressivestrengtheningof theteethandchangeinbitgeometrytoprovidemore chipping-crushingaction.Thesebitshavemoreclosely spacedteethwithalargeincludedangleandmoregage surfacetoresistthewearinharderandmoreabrasiveformations.
• Hardformationbits,TypeH,regularcirculationsteeltoothrockbitsaredesigned todrillhardformationswhichcontainamounts ofabrasivematerials.
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H Series
M Series
S Series
RockBlastingTechniqu
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t Whentochangeabit
• AttheendofaTriconebitslifethecuttingstructurebecomesineffectiveeitherthroughbreakageorwear, resultinginreducedpenetrationrate.
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RockDrillingEquipment
• IntegralDrillSteel
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Blasthole Patterns
Bench Blast Pattern in Quarry / Open Pit
RockBlastingTechniqu
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tBlastholes /Initiationpatternsforshotsfiredtoanopenface
RockBlastingTechniqu
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t UNDERGROUNDBLASTING
Pyramidordiamondcut(afterICI)Wedgecut(afterICI)
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Burncut(afterICI)
Fancut
Dragcut