# Common Blast Design Pitfalls Trouble Shooting The 19th Annual Surface Mined Land Reclamation Technology Transfer Seminar Jasper, Indiana December 5 th.

## Presentation on theme: "Common Blast Design Pitfalls Trouble Shooting The 19th Annual Surface Mined Land Reclamation Technology Transfer Seminar Jasper, Indiana December 5 th."— Presentation transcript:

Common Blast Design Pitfalls Trouble Shooting The 19th Annual Surface Mined Land Reclamation Technology Transfer Seminar Jasper, Indiana December 5 th & 6 th, 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

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’ 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 order Total failure of the explosive charge  Dynamic Shock Damage the initiator Destroy 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” = 11 ¼ ’  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 Current completely testable automated self-test and disarm features requires 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 design make 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 Stake 12345678910 Pyrotechnics/ms405411417383428405413412419421 Daveytronics/ms400 Grade Stake Actual Firing Times Daveytronic/ms Pyrotechnics/ms

4110 42134 51 6885102119 136 405153 428451434 496 490 515531 555 405574 417 383428 405413 412 41917 1 2 4 3 6 5789 10 - 4.25%+ 7% Avg. dev. + 2.85% Blast Simulation Using Actual Shock Tube Firing Times Out of Sequence Holes Poor Fragmentation Zone If we add 17ms between holes we have.... Potential FlyrockHigher Air & Ground VibrationsColumn Disruption 6ms

Blast Design ISEE Certificate Program, Level One-Practical Blasting Fundamentals