Blast design for underground mining applications 1 R. HOLMBERG
R. Holmberg Lima Nov 2011
Contents 2
Contents: 1. Purpose - applications 2. Surface blasting 3. Surface - underground 4. Tunneling 5. Function of cut 6. Design of parallel cut 7. Tunnel rounds 8. Contour bl blasting 9. Divided faces 10.. Sh 10 Shaf aftt si sink nkin ingg R. Holmberg Lima Nov 2011
11. 12.. 12 13.. 13 14. 15.. 15 16. 17.. 17
Mining me methods Ring Ri ng la layo yout utss Desi De sign gn for formu mula la Explosives Deco De coup uple led d ch char arge gess Pointers Ackn Ac know owle ledg dgem emen ents ts
Contents 2
Contents: 1. Purpose - applications 2. Surface blasting 3. Surface - underground 4. Tunneling 5. Function of cut 6. Design of parallel cut 7. Tunnel rounds 8. Contour bl blasting 9. Divided faces 10.. Sh 10 Shaf aftt si sink nkin ingg R. Holmberg Lima Nov 2011
11. 12.. 12 13.. 13 14. 15.. 15 16. 17.. 17
Mining me methods Ring Ri ng la layo yout utss Desi De sign gn for formu mula la Explosives Deco De coup uple led d ch char arge gess Pointers Ackn Ac know owle ledg dgem emen ents ts
Purpose & applications -1 3
The purpose is to: Efficiently excavate rock so that the pieces removed can be handled economically Avoid ore losses and waste rock intrusion Obtain the planned contour with no underbreak and as little overbreak as possible Leave the remaining rock stable for as long as the operation requires.
R. Holmberg Lima Nov 2011
Purpose & applications -2 4
The main applications are Mining; drifting and development work plus full workings Raise blasting and shaft sinking Quarrying Infrastructure; traffic tunnels, hydropower and water tunnels, parking garages, shelters, power house caverns etc Other applications; well springing, seismic operations etc.
R. Holmberg Lima Nov 2011
Surface blasting -1 5
Quarry; typically identical holes,
parallel, same diameter and same burden and spacing, B S pattern, same charging, q = 0,5-0,9 kg/m3. Road cut ; like quarry but contour holes , smaller hole diameters, smaller charges and on flatter angle
Foundations; essentially like
road cuts but vertical holes.
R. Holmberg Lima Nov 2011
Surface blasting -2 6
Open cast mine; like road cut but larger holes and contour gets special emphasis, sometimes smaller holes of different angles and depths. 1st row
7540
7520
7500
7480
production holes 17 m Ø311 mm helper & contour Ø152 mm
7460
7440
7420
15 m bench R. Holmberg Lima Nov 2011
presplit Ø127 mm
7400 4480
4500
4520
4540
4560
4580
4600
4620
4640
Surface vs underground - 1 7
Worldwide: OP >> UG, OP: ore < waste, UG: ore >> waste
R. Holmberg Lima Nov 2011
Surface vs underground - 2 8
Annually excavated volumes in Sweden • LKAB UG mines: 25 Mton Fe-ore, 20 Mton waste • Aitik open pit mine: 28 Mton Cu-ore, 30 Mton waste. Other mines and crushed stone, infrastructure projects etc. ~80Mton •
•Makes about 180 Mton or 6 m3 per capita •70 kton explosives makes about 8 kg per capita
R. Holmberg Lima Nov 2011
Surface vs underground - 3 9
Tunnelling:
Underground blasting; often more complicated drilling patterns and combinations of blasting methods
fire-in-the-hole!
blasting plan charged & primed R. Holmberg Lima Nov 2011
Tunnelling - 1 10
What has happened in tunnelling recent 25 years?
R. Holmberg Lima Nov 2011
Tunnelling - 2 11
blasting = (38% 2007), small part of total excavation work but outcome often decisive for downstream operations R. Holmberg Lima Nov 2011
Tunnelling - 3 12
look-out angle needed to make room for drilling next round, min 0.2-0.3 m, design burden applied to hole bottom (toe) and at face deduct look-out Start- first one free face - the tunnel face. Blasting is confined and specific charge is high q = 1,5-2 kg/m3 R. Holmberg Lima Nov 2011
