Common Blast Design PitfallsTrouble Shooting

The 19th Annual Surface Mined LandReclamation Technology Transfer Seminar

Jasper, Indiana

December 5th & 6th, 2005

Wm. J. Reisz

Improper Hole Placement holes to close to the face optimal burdens & spacings

Transient Pressures/Dynamic Shock

deadpress basic blast design insufficient decking

Electronic Initiation Systems why electronics? pyrotechnic demonstration

Common Blast Design Pitfalls

Hole Placement

Hole Placement

Spoil

Spoil

Optimum Burdens & Spacings

Determine Bench Parameters bench height width length hole diameter explosives type retangular 1:1.2 staggered 1:1.5

105’

25’

25’

25’

15’

15’

Non-Proportional Burdens

105’

105’ ÷ 4.7 = 22.3’

82.7’

60.4’

38.1’

15.8’

105’

16.4’Crest burden ≈ .7 X inner row burden

110’

110’ ÷ 4.7 = 23.4’

110’

86.6’

63.2’

39.8’

16.4’

Proportional Burdens & Spacings

153’ ÷ 6 = 25.5’

153’

7 holes = 6 inner hole spacings

Blast Design

ISEE Certificate Program, Level One-Practical Blasting Fundamentals

Transient Pressures Deadpress

Fire at a low orderTotal failure of the explosive charge

Dynamic ShockDamage the initiatorDestroy the booster Fire at the wrong time Sympathetic Detonation

Bottom FirstInsufficient Decking

Bottom First

Bottom Up ↔12 - 15 times borehole diameter

For example: 9” dia. X 15 = 135” ÷ 12” = 11¼’

Stemming Between Decks

Rule of Thumb

Top Deck First

Top First

Top Down ↔ 1 foot for every inch of borehole diameter

For example: 9” dia. X 1’ = 9’ stem

Stemming Between

Decks

Rule of Thumb

Why Electronics?

Why Electronic Detonator Systems? Eliminate pyrotechnic scatter

poor rock fragmentation high ground vibration levels high air blast levels greater flyrock potential

Why Electronic Detonator Systems? Eliminate pyrotechnic scatter Delay selection, site specific Safety

immunity to RF, EMI and Stray Currentcompletely testable automated self-test and disarm featuresrequires specific blast machine to fire

Eliminate pyrotechnic scatter Delay selection, site specific Safety Optimized Blast Performance

Why Electronic Detonator Systems?

Vibration Control Flyrock Control Floor Control Wall Control Improved Cast Percentage

Eliminate pyrotechnic scatter Delay selection, site specific Safety Autonomous Operation Optimized Blast Performance Inventory Control

Why Electronic Detonator Systems?

overcome poor blast designmake your job easier

What Electronic Detonator Systems

Will Not Do

Comparison to pyrotechnic dets

Detonators Attached to Grade Stake

Shock Tube 400 ms

Daveytronic 400 ms

Comparison to pyrotechnic dets

Daveytronic

Comparison to pyrotechnic dets

Grade Stake1 2 3 4 5 6 7 8 9 10

Pyrotechnics/ms 405 411 417 383 428 405 413 412 419 421

Daveytronics/ms 400 400 400 400 400 400 400 400 400 400

Grade Stake

Actual Firing Times

Daveytronic/ms

Pyrotechnics/ms

4110 42134 51 68 85 102 119 136405 153428 451 434 496 490 515 531 555405 574417 383 428 405 413 412 41917

1 2 4 3 6 5 7 8 9 10

- 4.25%+ 7%Avg. dev. + 2.85%

Blast Simulation Using Actual Shock Tube Firing Blast Simulation Using Actual Shock Tube Firing TimesTimes

Out of Sequence Holes

Poor Fragmentation Zone

If we add 17ms between holes we have . . . .If we add 17ms between holes we have . . . .

Potential FlyrockHigher Air & Ground VibrationsColumn Disruption

6ms 6ms

Blast Design

ISEE Certificate Program, Level One-Practical Blasting Fundamentals

Questions or Questions or Comments?Comments?

ThanksThankswww.daveytronic.comwww.daveytronic.com

Wm. J. Reisz