Common Blast Design Pitfalls

1. Trouble Shooting Common Blast Design Pitfalls The 19th Annual Surface Mined Land Reclamation Technology Transfer Seminar Jasper, Indiana December 5th & 6th, 2005 Wm. J. Reisz

2. Common Blast Design Pitfalls • 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

4. Hole Placement

5. Hole Placement Spoil Spoil

7. Optimum Burdens & Spacings • Determine Bench Parameters • bench height • width • length • hole diameter • explosives type • retangular 1:1.2 • staggered 1:1.5

8. Non-Proportional Burdens 15’ 25’ 25’ 105’ 25’ 15’

9. Proportional Burdens & Spacings Crest burden ≈ .7 X inner row burden 16.4’ 16.4’ 15.8’ 38.1’ 39.8’ 110’ 105’ 63.2’ 60.4’ 86.6’ 82.7’ 110’ 105’ 153’ 105’ ÷ 4.7 = 22.3’ 7 holes = 6 inner hole spacings 153’ ÷ 6 = 25.5’ 110’ ÷ 4.7 = 23.4’

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

11. 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

12. Insufficient Decking Bottom First

16. < Bottom First Rule of Thumb • Bottom Up ↔12 - 15 times borehole diameter For example: 9” dia. X 15 = 135” ÷ 12” = 11¼’ Stemming Between Decks

17. Top Deck First

18. < Top First Rule of Thumb • Top Down ↔ 1 foot for every inch of borehole diameter For example: 9” dia. X 1’ = 9’ stem Stemming Between Decks

19. Why Electronics?

20. Why Electronic Detonator Systems? • Eliminate pyrotechnic scatter • poor rock fragmentation • high ground vibration levels • high air blast levels • greater flyrock potential

26. 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

27. Why Electronic Detonator Systems? • Eliminate pyrotechnic scatter • Delay selection, site specific • Safety • Optimized Blast Performance • Vibration Control • Flyrock Control • Floor Control • Wall Control • Improved Cast Percentage

28. Why Electronic Detonator Systems? • Eliminate pyrotechnic scatter • Delay selection, site specific • Safety • Autonomous Operation • Optimized Blast Performance • Inventory Control

29. What Electronic Detonator SystemsWill Not Do • overcome poor blast design • make your job easier

30. Comparison to pyrotechnic dets

31. Detonators Attached to Grade Stake Shock Tube 400 ms Daveytronic 400 ms

32. Comparison to pyrotechnic dets Daveytronic

33. Comparison to pyrotechnic dets

35. Actual Firing Times Grade Stake Pyrotechnics/ms Daveytronic/ms

36. Blast Simulation Using Actual Shock Tube Firing Times If we add 17ms between holes we have . . . . 405 405 34 68 85 515 102 412 531 119 421 574 153 496 51 136 0 411 428 17 451 383 434 428 490 419 555 417 405 413 - 4.25% + 7% Avg. dev. + 2.85% 6ms 6ms 2 6 4 5 7 8 9 1 3 10 Higher Air & Ground Vibrations Poor Fragmentation Zone Potential Flyrock Column Disruption Out of Sequence Holes

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

38. Questions or Comments?

39. Thanks www.daveytronic.com Wm. J. Reisz