Blast Design Mathematics - Enaex.ppt

8/22/2019 Blast Design Mathematics - Enaex.ppt

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Austin Powder Company

Blast Design for Surface M ining


Corporate Technical Services


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Blast Design for Surface

Mining

Purpose of blasting.

Basic design considerations.

Blasting nomenclature.

Blast geometry mathematics.

Delay timing considerations.


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1 The Purpose of Blasting


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Purpose of Blasting

To facilitate the cost efficient

extraction of ore through rockparticle size reduction and

improvement of particle

presentation to excavating

equipment.


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Purpose of Blasting

Fragmentation should aim to satisfy the

demands of the processing plant and the endproduct required.

Characteristics of the muck-pile should be

designed to improve the efficiency of the

excavating equipment.


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2 Blast Design Considerations


7/30Austin Powder Company

Design Considerations

Drilling Equipment Available

Range of hole diametersOptimum depth capabilities

Explosives Selection

Bulk or packaged productsDensity, weight strength, VOD

Water resistance




Material and Region to be Blasted

Free face availabilitySinking cuts

Controlled blasting

Excavating & Processing EquipmentSize and variety (i.e. wheeled loader, front

shovel, back-hoe etc.)

Processing plant capabilities




Neighborhood

Proximity of residencesNoise and dust emission considerations

End use of material

OreWaste



3 Blast Geometry Nomenclature



Blasting Nomenclature

H

J LJ

D

= Blast Hole Angle

L = Length of Subdrilling

D = Horizontal Stand-off

B = Layout (Apparent) Burden

D

D

1

BL

L

1

J

B H

J

HL

H = Vertical Face Height

L = Face Length

L = Length of Blast Hole

B = True Burden

J = True (Vertical) Subdrilling

B

B

2

1



4 Pattern Geometry Mathematics



Pattern Geometry

Mathematics

Where do I start?

Required production ratesPre-existing drilling equipment capabilities

Scaled distance considerations (lb. per delay)

Pre-existing mine site (established benches)Fragmentation particle size limits (max. size)

In-situ geology (thickness of seams)

State and local regulations (max. blast size)


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Pattern Mathematics

Selecting a bench height or a hole diameter:

DH 12.006.0H = Bench Height [m]

D = Drill hole diameter [mm]


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Pattern Mathematics

Establishing the burden:

E

R

ED

SG

SGB

018.0024.0

B = Burden [m]SG = Specific gravity of explosives

SG = Specific gravity of rock

DE = Diameter of fully coupled explosive column [mm]

Konya & Walter

E

R


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Pattern Mathematics


3

1

119.0

R

E

E

SG

SGDB

B = Burden [m]SG = Specific gravity of explosives

SG = Specific gravity of rock

DE = Diameter of fully coupled explosive column [mm]

Ash

E

R


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Pattern Mathematics


B = Burden [m]D = Diameter of fully coupled explosive column [mm]

Borg, Chiapetta

& Sterner

E

EDB )035.0025.0(


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Pattern Mathematics

Blast hole spacing:H

B 4H

B< 4

S B 2 SH B

( )2

3

S B 1 4. SH B

( )7

8

Instant

Delayed

Konya & Walter

(1)


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Pattern Mathematics

Blast hole spacing:

Borg, Chiapetta

& Sterner

S = Spacing [m]B = Burden [m]

S B 10 18. .


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Pattern Mathematics

Sub-drilling depth:

Borg, Chiapetta

& Sterner

B = Burden [m]J = Sub-drilling [m]

*Crater angle of 120o to 160o

J B 0 2 0 5. .


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Pattern Mathematics

Stemming Column Length:

Borg, Chiapetta

& Sterner

B = Burden [m]T = Stemming [m]

T B 07 13. .


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Pattern Mathematics

Stemming Material Particle Size:

Konya & Walter

T = Stemming particle size [mm]D = Drill hole diameter [mm]

T DS

20

S


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Pattern Mathematics

Stone Deck Length:

TD = Minimum length of stone deck consisting ofparticles of size TS [m]

D = Drill hole diameter [mm]

DTD )012.0006.0(

Wet HoleDry Hole


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Pattern Mathematics

Base Charge Length:

Borg, Chiapetta

& Sterner

E = Base charge length [m]

B = Average burden [m]J = Sub-drilling depth [m]

Total Eb = 50% to 100% of B

b

E B Jb 0 3 0 5. .


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Pattern Mathematics

Base Charge Length:

E = Base charge length [m]J = Sub-drilling depth [m]b

JEb 2


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5 Blast Pattern Timing


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Blast Pattern Timing

Hole-to-Hole Delay Range:

Hole-to-hole delay = 0 to 15 milliseconds

per meter of spacing

Konya & Walter


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Hole-to-Hole Delays to Maximize Fragmentation:

Sands, Loams, Marls and Coals 6 - 7

Some Limestones, Rock Shale and some Shales 5 - 6

Compact Limestones and Marbles, some Granites 4 - 5

and Basalts, Quartzite Rocks and some Gneisses

and Gabbros

Diabase, Diabase Porphyrites, Compact Gneisses 3 - 4

and Mica Schists and Magnetites

Rock Type ms/m

Konya & Walter


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Row-to-Row Delay Range:

Row-to-row delay = 7 to 50 milliseconds per

meter of burden

Konya & Walter


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A ti P d C


Row-to-Row Delays and Effects:

Violent excessive air-blast and back-break 7

High pile close to face, moderate air-blast and back-break 7 - 10

Average pile height, average air-blast and back-break 10 - 13

Scattered pile with minimum back-break 13 - 20

Effects ms/m

Konya & Walter

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Blast Design Mathematics - Enaex.ppt