16613018 blasting operations
TRANSCRIPT
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Blasting OperationsBlasting Operations
Prepared byPrepared by
Dr. Ayman ElDr. Ayman El--MidanyMidany
44thth year Miningyear Mining
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WEEK ONEWEEK ONE
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IntroductionIntroduction
GeneralGeneral typestypes ofof ExplosivesExplosives
CommercialCommercial explosivesexplosives
MilitaryMilitary explosivesexplosives
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Ingredient Chemical formula Function
Ethylene glycol dinitrate
Nitrocellulose (guncotton)
Nitroglycerin
NitrostarchTrinitrotoluene (TNT)
Metallic powder
Black powder
Pentaerythritol tetranitrate
(PETN)
Lead azide
Mercury fulminateAmmonium nitrate
Liquid oxygen
Sodium nitrate
Potassium nitrate
Ground coal - Charcoal
Paraffin
SulfurFuel oil
Wood pulp
Lampblack
Kieselguhr
Chalk -Calcium carbonate
Zinc oxide
Sodium chloride
C2H4(NO3)2C6H7(NO3)2O2C3H5(NO3)3
C7H5N3O6Al
NaNO3 + C+ S
C3H8N4O12
Pb(N3)2
Hg(ONC)2NH4NO3O2NaNO3KNO3C
CnH2n+2
S(CH3)2(CH2)
(C6H16O3)nC
SiO2CaCO3ZnO
NaCI
Explosive base lowers freezing point
Explosive base gelatinizing agent
Explosive base
Explosive baseExplosive base
Fuel sensitizer : used in high density slurries
Explosive base
Explosive base
Explosive used in blasting caps
Explosive used in blasting capsExplosive base : oxygen carrier
Oxygen carrier
Oxygen carrier lowers freezing point
Oxygen carrier
Combustible, or fuel
Combustible, or fuel
Combustible, or fuelCombustible, or fuel
Combustible, absorbent
Combustible
Absorbent prevents caking
Antacid
Antacid
Flame depressant (permissible explosives)
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Chemical explosivesChemical explosives
isis aa compoundcompound oror mixturemixture whichwhich isis capablecapable ofofundergoingundergoing extremelyextremely rapidrapid decompositiondecomposition..
AnAn explosionexplosion cancan bebe brokenbroken downdown intointo fourfourphasesphases
ReleaseRelease ofof gasgas
IntenseIntense heatheatExtremeExtreme pressure,pressure, andand
TheThe explosionexplosion
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Chemical explosivesChemical explosives
WhenWhen thethe explosiveexplosive isis detonated,detonated,
gasgas isis released,released, temperaturetemperature ofof thethe gasgas increases,increases,
pressurepressure alsoalso increasesincreases (Charles(Charles law)law)..
movemove andand breakbreak thethe rockrock..
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How to compare explosivesHow to compare explosives
StrengthStrength
DetonatingDetonating velocityvelocity
FumeFume classclass WaterWater resistanceresistance
DensityDensity
PhysicalPhysical characteristicscharacteristics
StorageStorage
FreezingFreezing
DetonationDetonation pressurepressure
EnergyEnergy
SensitivitySensitivity SensitivenessSensitiveness
FlammabilityFlammability
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How to compare explosivesHow to compare explosives
StrengthStrength :: %% ofof activeactive materialmaterial
VelocityVelocity of of DetonatingDetonating (VOD)(VOD):: isis thethe
velocityvelocity atat whichwhich thethe detonationdetonation wavewave movesmoves
throughthrough thethe explosiveexplosive (ft/s(ft/s oror m/s)m/s)
FumeFume classclass :: thethe amountamount ofof toxictoxic fumesfumeswhichwhich determinedetermine itsits safetysafety toto bebe usedused inin
particular particular situationsituation suchsuch asas undergroundunderground
operationsoperations..
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How to compare explosivesHow to compare explosives
DetonationDetonation pressurepressure :: isis thethe pressure pressure behindbehind
thethe detonationdetonation frontfront..
EnergyEnergy
SensitivitySensitivity :: thethe minimumminimum energy/pressureenergy/pressure
neededneeded forfor detonationdetonation..
SensitivenessSensitiveness:: measuremeasure ofof explosionexplosion wavewave
spreadingspreading fromfrom oneone stickstick toto anotheranother..
FlammabilityFlammability :: easinesseasiness toto igniteignite byby flameflame oror
heatheat
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How to compare explosivesHow to compare explosives
WaterWater resistanceresistance :: isis thethe abilityability toto resistresistcontaminationcontamination oror aa reductionreduction inin strengthstrength whenwhenexposedexposed toto waterwater.. SometimesSometimes determineddetermined byby thethe
lengthlength ofof timetime itit cancan bebe submergedsubmerged inin waterwater andandstillstill performperform asas designeddesigned..
DensityDensity :: isis thethe explosiveexplosive wtwt perper givengiven volumevolume..
AA cartridgecartridge ofof 9090 stickssticks perper 5050--lblb casecase isis denserdenserthanthan aa cartridgecartridge ofof 110110 stickssticks perper 5050--lblb casecase.. AidAidinin blastblast designdesign..
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How to compare explosivesHow to compare explosives
PhysicalPhysical characteristicscharacteristics:: commercialcommercial explosivesexplosives
cancan taketake threethree basicbasic formsforms:: granular,granular, gelatin,gelatin, andand
slurryslurry.. TheThe formform dependsdepends onon thethe formula,formula, andand thethe
choicechoice ofof formform dependsdepends onon thethe usageusage requiredrequired..
TheThe packagepackage forfor thethe samesame explosiveexplosive productproduct maymay
alsoalso varyvary accordingaccording toto usageusage.. ForFor example,example, aa
slurryslurry cancan bebe pumpedpumped intointo aa boreholeborehole withwith nonocontainer,container, oror itit cancan bebe packagedpackaged inin polyethylenepolyethylene
bagsbags toto permitpermit handlinghandling inin smallersmaller amountsamounts..
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How to compare explosivesHow to compare explosives
StorageStorage:: howhow explosiveexplosive cancan bebe storedstored withoutwithout
affectingaffecting itsits safety,safety, reliability,reliability, andand performanceperformance..
EarlyEarly nitroglycerinnitroglycerin (NG)(NG) dynamitesdynamites werewere
extremelyextremely poorpoor forfor storingstoring duedue toto separationseparation ofof
NGNG fromfrom thethe otherother componentscomponents andand createscreates anan
extremelyextremely hazardoushazardous conditioncondition..
FreezingFreezing :: importantimportant forfor safetysafety andand performanceperformance
especiallyespecially inin coldcold climateclimate.. AnitfreezingAnitfreezing additivesadditives
maymay bebe usedused..
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Drills and drillingDrills and drilling
TheThe drillingdrilling systemsystem consistsconsists ofof thethe drilldrill:: thethe drilldrill
steel,steel, oror rodrod;; andand thethe bitbit.. TheThe bitbit penetratespenetrates thethe
rockrock byby thethe forceforce itit imposesimposes onon thethe rockrock.. BitsBits areare
designeddesigned forfor percussion,percussion, rotaryrotary drilling,drilling, oror bothboth..
HandHand heldheld drillsdrills
ExternalExternal percussionpercussion drillsdrills
DownDown--thethe--holehole drillsdrills
RotaryRotary drillsdrills
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Rock Shear strengthRock Shear strength
RockRock ConditionCondition
ShearShear
strength,strength,
lb/inlb/in22
SandstoneSandstone SoftSoft
MediumMedium
Hard grayHard gray
FineFine--grained browngrained brown
MediumMedium--grained friable graygrained friable gray
15001500
30503050
47204720
36003600
28402840
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Rock Shear strengthRock Shear strength
RockRock ConditionCondition
ShearShear
strength,strength,
lb/in2lb/in2
LimestoneLimestone Hard flossiliferrousHard flossiliferrousHard grayHard gray
Medium crystallineMedium crystalline
4160416065206520
76007600
SiltstoneSiltstoneDolomiteDolomite
quartzitequartzite
300030001270012700
1060010600
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Drill SelectionDrill Selection
SizeSize ofof projectproject :: drilldrill typetype andand sizesize
HoleHole diameterdiameter :: drilldrill typetype andand bitbit sizesize
DepthDepth ofof cutcut :: longlong oror shortshort RockRock hardnesshardness:: percussionpercussion ((44--66..55)) oror rotaryrotary ((22--
33..55)) onon MohsMohs scalescale
CapitalCapital :: machinemachine priceprice CostCost :: costcost per per footfoot ofof borehole borehole needneed
specializedspecialized operatoroperator
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WEEK TWOWEEK TWO
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Firing systemsFiring systems
BlastingBlasting CapCap
DetonatingDetonating systemssystems
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Blasting CapsBlasting Caps
BlastingBlasting CapCap :: areare smallsmall cylindricalcylindrical tubestubes thatthat
detonatedetonate capcap--sensitivesensitive explosivesexplosives.. TheyThey areare
usuallyusually mademade ofof coppercopper oror aluminumaluminum andand
containscontains anan explosiveexplosive..
ThereThere areare threethree typestypes ofof blastingblasting capscaps::
CommonCommon capscaps MillisecondMillisecond delaysdelays (MS(MS delays)delays)
StandardStandard delaysdelays
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Common Blasting CapsCommon Blasting Caps DetonatedDetonated byby aa fusefuse
NowNow theythey areare thethe leastleast commoncommon
CopperCopper oror aluminumaluminum CylinderCylinder
3838 mmmm longlong XX 66 mmmm dia,dia, closedclosed atat oneone endend..
ContainsContains twotwo typestypes ofof chargescharges :: ignitingigniting chargecharge andand
thethe basebase chargecharge..
AA safetysafety fusefuse isis insertedinserted intointo thethe openopen endend ofof thethe capcaptoto ensureensure thatthat thethe flameflame reachesreaches thethe ignitingigniting chargecharge
completelycompletely.. ToTo preventprevent waterwater andand contaminantscontaminants fromfrom
enteringentering thethe capcap andand inhibitinginhibiting detonationdetonation..
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Common Blasting CapsCommon Blasting Caps
WhenWhen thethe fusefuse isis ignited,ignited, thethe powderpowder corecore burns,burns,
actingacting asas aa vehiclevehicle throughthrough whichwhich thethe firefire isis
transmittedtransmitted toto thethe ignitingigniting chargecharge endend ofof thethe capcap..
TheThe burning burning fusefuse spitsspits aa flameflame resemblingresembling aa jetjet
flameflame calledcalled asas ignitionignition spitspit..
WhenWhen thethe flameflame travelstravels toto thethe cap,cap, itit ignitesignites thetheignitionignition charge,charge, whichwhich detonatesdetonates thethe basebase charge,charge,
whichwhich inin turnturn detonatesdetonates thethe explosiveexplosive chargecharge thatthat isis
beingbeing primedprimed withwith thethe capcap..
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Common Blasting CapsCommon Blasting Caps
Base charge
Ignition
charge
Fuse
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Electric Blasting CapsElectric Blasting Caps
MoreMore controllablecontrollable methodmethod
ContainsContains chargescharges likelike thethe commoncommon cap,cap, butbut
insteadinstead ofof safetysafety fusefuse thethe capcap containscontains twotwo wireswiresthatthat meetmeet atat aa bridgebridge wirewire..
whenwhen electricelectric currentcurrent isis applied,applied, thethe bridgebridge wirewire
burns,burns, ignitingigniting thethe chargecharge inin thethe capcap..
EnablesEnables thethe blasterblaster
toto choosechoose thethe suitablesuitable timetime ofof detonationdetonation
toto shootshoot moremore holesholes thanthan thethe safetysafety fusefuse methodmethod
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Delay Blasting CapsDelay Blasting Caps
AreAre capscaps thatthat areare detonateddetonated by by electricityelectricity inin
variousvarious timetime--delaydelay intervalsintervals..
TwoTwo typestypes :: standardstandard andand millisecondmillisecond (MS)(MS).. AdvantagesAdvantages ofof (MS)(MS) areare::
ReduceReduce groundground vibrationvibration
ImproveImprove fragmentationfragmentation
ProduceProduce lessless flyrockflyrock
ReduceReduce costscosts
ReduceReduce overbreakoverbreak
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Delay BlastingDelay Blasting
Flyrock, excessive movement of blasted rock in the
air, caused by not using delay blasting. Second row
cannot move toward face and therefore must
either fly or remain in place.
Free face1st rowFlyrock
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Delay BlastingDelay Blasting
Delay blasting can help reduce flyrock by
permitting the rock to move in the direction
desired rather than moving haphazardly
through the air.
Blasting without delays requires more drilling
and explosive to break the rock because the rock
tends to resist breakage and lack of a sufficientnumber of free faces.
Delay blasting reduces overbreak.
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Delay BlastingDelay Blasting
Free face
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Other Blasting CapsOther Blasting Caps
Vented caps : with vents to delay blasting
to reduce the combustion rate in the
blasting cap.
Composition Electric caps : contains amixture of chemical compounds.
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Detonating SystemsDetonating Systems
The main components of an electric detonating system
Blasting cap
Blasting wire Power source or blasting machine
Detonating cord
Transmit detonations from blasting cap to explosives Less sensitive than blasting caps
Is a high explosive and burns at speed > 4miles/second
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Blasting CircuitsBlasting Circuits
Three types of circuits
Single-series
Straight parallel
Parallel-series
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Blasting CircuitsBlasting Circuits
Problems
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Theory of BreakageTheory of Breakage
Purpose of blasting
One solid piecep smaller pieces (fragmentation)
pto be moved or excavated (movement).
Underground blasting, for example, requires
greater fragmentation than surface blasting
because of the size of the equipment that can be
used and the difficulty of access.
Get the desired results with a minimum cost
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Theory of BreakageTheory of Breakage
Involves two basic processes:
Radial cracking
Flexural rupture
Rock is stronger in compression than in tension.
Therefore, the easiest way to break rock is to
subject it to a tensile stress greater than itsultimate strength in tension.
Rocks are heterogeneous (contain different types
of rocks). They differ in their density.
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Theory of BreakageTheory of Breakage
Borehole
Free face
Compressionwaves
Radial cracking
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Theory of BreakageTheory of Breakage
The distance from the borehole to the free
face is the burden.
The denser the rock the faster the waves
Proper fragmentation when enough to
travel to the face and back overcoming the
tensile strength of the rock.
Along the face the outermost edge is
stretched in tension which causes cracks.
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Flexural RuptureFlexural Rupture
The second process in breaking rock by
bending the rock to the point where the
outside edge, the side in tension, breaks. Caused by the rapid expansion of gases in
borehole.
Analogous to the bending and breaking of abeam.
Movement or displacement are required in
addition to cracking.
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Flexural RuptureFlexural Rupture
After detonation the redial cracks expands
and the gas starts to the movement by
putting a CS
against the borehole wallcausing its bending.
The deeper the hole, the greater the burden
and borehole spacing. M = wl2/8 where w is the load (burden), l is
the borehole length.
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StemmingStemming
Is non-explosive material that is placed in the borehole
between the top of the explosive column and the collar of
the hole.
Sand, drill fines, or gravel
Confine and delay the escape of expansive gases and
increases the explosives efficiency (reduces the explosive
used).
Reduce the flyrocks, increase ground vibration, and air
blast
Rifling : in case of impropoer stemming, blowing of the
stemming material.
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Angle of BreakageAngle of Breakage
Is the measured angle at which a homogeneous material
can be expected to break from the explosive charge to the
free face.
135r
90r
Free face
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WEEK THREEWEEK THREE
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Blast DesignBlast Design
Is the safe and economic way to do blasting
Factors affecting blasting designFactors affecting blasting design
Geological factors (out of blasters control)
Controllable factors
Borehole dia.
BurdenSpacing
Stemming
Design of the delay firing system.
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Hole DiameterHole DiameterDepends on
The availability of the equipment
The depth of the cut
The distance of the nearest structure.
Max dia. Depends on the hole depth L (ft) = 2D (in)
There are four methods to decrease the explosives amount:
Use delay firing
Shorten the depth of the cut
Decrease the hole dia
Use decking technique
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Burden & spacing determinationBurden & spacing determination
Burden is the distance from the blast hole to the nearest
perpendicular free face.
Free face
Spacing
Burden
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Burden & spacing determinationBurden & spacing determination
Andersen Formula B= (dL)0.5
B : burden, ft d : borehole dia, in
L : borehole Length, ft
Langefors Formula V= (db/33) [Ps/cf(E/V)]0.5
V : burden, m db : dia of drill bit, mm
P : degree of packing = 1-1.6 kg/dm3
s : wt strength of explosives (1.3 for gelatin)
c : rock constant, generally 0.45
f : 1 degree of fraction, for straight hole = 1
E/V = ratio of spacing to burden
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Spacing determinationSpacing determination
Spacing is the distance between blast holes fired in the same
row
It is necessary to complete burden calculations before
determining the spacing.
S= (BL)0.5
B : burden, ftL : borehole Length, ft
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Controlled BlastingControlled Blasting
To control overbreak and to aid the stability of the
remaining rock formation.
There are 4 methods
Line drilling (unloaded), Fig.8-2 Cushion blasting
Smooth-wall blasting
Presplitting
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Controlled BlastingControlled Blasting Line drillingLine drilling
Provides a plane of weakness to which the rock can break.
Helps to reflect shock waves,
Reduces the shattering effect of the rock outside the
perimeter. Do not exceed 3 in in dia and are spaced one to four
diameters apart (due to cost).
Are not loaded
Requires more drilling more than the other controlled
blasting methods.
Is not very effective in non-homogeneous formations
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Controlled BlastingControlled Blasting Line drillingLine drilling
Unloadedline drill
holes
Freeface
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Cushion BlastingCushion Blasting Requires a single row of holes ( 2 to 3.5 in) in dia.
Permits a reduction in the No. of holes required by line-drilling
Unlike line-drilling holes, the cushion holes are loaded with light
charges.
Holes are fully stemmed between charges, allowing no air gap, and
are fired after the production shot has been excavated.
The stemming acts as a cushion to protect the finished wall from the
shock waves. The larger the borehole, the greater the cushion.
Not suitable for underground - tough stemming requirements.
Drawbacks: (1) requires removal of excavated material before firing
(costly due to production delay no excavation for entire area at
once). (2) Sometimes the production shot can break back to the
cushion holes, creating redrilling problems and causing loading
changes.
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SmoothSmooth--wall Blastingwall Blasting Similar to cushion blasting
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PrePre--splittingsplitting
Creates a plane of shear in solid rows along the desiredexcavation before the production blast.
All holes are loaded like cushion blasting
Reduces overbreak
Reduces the vibration