Fig 1. No free face for three row blast
Blast geometry :
- Burden : 5.65 meter
- Spacing : 6.5 meter
- Stemm : wet 2.3 meter
- Stemm : dry 3.5 meter
- Sub drill : 1 meter
- No of Holes : 50 (29 dry, 21 wet)
- Avg depth : 8 meter
- Volume : 12.854 bcm
Explosive :
- Dry Holes : ANFO (94:6) (diameter expl 159 mm)
- Wet Holes : ANFO (94:6) + Liner (diameter expl 121 mm)
Powder Factor : 0.26 kg/bcm
Coal dipping : 70o
Comment :
- No fractured at top of coal roof (no Back break)
- Pad rock blast or box cut ( no free face)
- Heaping material around 2 meter
- No Fly rock
- Oxygen balance
- Total Blast Cost ( TBC : USD 0.122)
- Total Drill Blast Cost (TDBC : USD 0.198)
Fig 2. Fragmentation on top area
Good fragmentation on top area (PF 0.24, burden 5.65 meter spacing 6.5 meter)
Fig. 3. Heaping material and digging activity 2-3 meter heaping material
Seam 12 (V cut)
Fig. 4 Three rows Blast whit no maximal Free face
Fig.5 Good Fragmentation on top Area, Good heaping (2-3 meter)
Fig.6 Material Moved (throw) to free face area (good fragmentation)
Blast geometry :
- Burden : 6.09 meter
- Spacing : 7.0 meter
- Stemm : wet 2.3 meter
- Stemm : dry 3.3 meter
- Sub drill : 1 meter
- No of Holes : 56 (51 dry, 5 wet)
- Avg depth : 7.78 meter
- Volume : 16.186 bcm
Explosive :
- Dry Holes : ANFO (94:6) (diameter expl 159 mm)
- Wet Holes : ANFO (94:6) + Liner (diameter expl 133 mm)
Powder Factor : 0.26 kg/bcm
Coal dipping : 70o
Comment :
- No Back break
- V cut
- Heaping material around 2-3 meter
- Throwing to free face area
- No Fly rock
- Oxygen balance
- Total Blast Cost ( TBC : USD 0.118)
- Total Drill Blast Cost (TDBC : USD 0.194)
Seam 12 (V Cut)
Fig.7 Blast with good free face
Fig. 8 Good fragmentation and Throwing
Blast geometry :
- Burden : 4 – 6.09 meter
- Spacing : 7.0 meter
- Stemm : dry 3.3 meter
- Sub drill : 1 meter
- No of Holes : 45 dry
- Avg depth : 7.82 meter
- Volume : bcm
Explosive :
- Dry Holes : ANFO (94:6) (diameter expl 159 mm)
Powder Factor : 0. kg/bcm
Coal dipping : 70o
Comment :
- No Back break
- V cut
- Good Throwing to free face area
- No Fly rock
- Oxygen balance
- Total Blast Cost ( TBC : USD 0.144)
- Total Drill Blast Cost (TDBC : USD 0.22)