600
operations with around 9 to 10 m bench height. Burden varies from 3–3.5 m, the spacing
between 4–5 m, and quantity of charge per hole between 40–60 kg for 115 mm hole diameter.
Accordingly, the stemming column in the blast holes also varies between 2.5–3 m. Staggered
pattern and the square grid pattern of holes are drilled. The blast hole depth is 10 meter
including 10% subgrade drilling.
The non-electric (NONEL) system of initiation (TLDs 17/250 ms and 25/250 ms) is being
used for blasting work in combination with ANFO and cast booster weighing 150 gm. In
case of watery hole during the rainy season and in the lower bench, large diameter slurry
explosive cartridges (Aquadyne and super gel) were used for blasting. Each blast is monitored for ground vibration and fragmentation and necessary care has been taken based on
the report obtained. Minimate plus device is used for measurement of ground vibration in
the field survey. In blasting, two to three rows of holes are blasted at a time and maximum of
60 holes are blasted at a time with proper initiation, charging pattern and charge per delay.
Delay is set in such a way that each hole gets the adequate free face and blasted at a time.
Hence optimum fragmentation with reduced ground vibration is achieved. So practically the
charge per delay is only the amount of explosive placed in a single hole, i.e. 40–60 kg.
The developed system was installed in Mine-A. Eleven PPV values were captured at each
measured point using a test bed along with Minimate Plus seismograph. The obtained PPV
values are varied owing to the distance between the blast point and the monitored location
and other parameters such as a charge per hole, number of holes, spacing, burden, and hole
depth. The test setup was placed at different monitoring locations (distances) every day to
Figure 6. Installation of test bed in Mine-A.
Figure 7. Recorded PPV using accelerometer based test bed at 600 distance.
o_~
08
-
07
"'
--06
e
e
0'5
'-'
c
0_4
....
03
c:J
0
0_2
~
>
01
C)
20
Time (ms)
operations with around 9 to 10 m bench height. Burden varies from 3–3.5 m, the spacing
between 4–5 m, and quantity of charge per hole between 40–60 kg for 115 mm hole diameter.
Accordingly, the stemming column in the blast holes also varies between 2.5–3 m. Staggered
pattern and the square grid pattern of holes are drilled. The blast hole depth is 10 meter
including 10% subgrade drilling.
The non-electric (NONEL) system of initiation (TLDs 17/250 ms and 25/250 ms) is being
used for blasting work in combination with ANFO and cast booster weighing 150 gm. In
case of watery hole during the rainy season and in the lower bench, large diameter slurry
explosive cartridges (Aquadyne and super gel) were used for blasting. Each blast is monitored for ground vibration and fragmentation and necessary care has been taken based on
the report obtained. Minimate plus device is used for measurement of ground vibration in
the field survey. In blasting, two to three rows of holes are blasted at a time and maximum of
60 holes are blasted at a time with proper initiation, charging pattern and charge per delay.
Delay is set in such a way that each hole gets the adequate free face and blasted at a time.
Hence optimum fragmentation with reduced ground vibration is achieved. So practically the
charge per delay is only the amount of explosive placed in a single hole, i.e. 40–60 kg.
The developed system was installed in Mine-A. Eleven PPV values were captured at each
measured point using a test bed along with Minimate Plus seismograph. The obtained PPV
values are varied owing to the distance between the blast point and the monitored location
and other parameters such as a charge per hole, number of holes, spacing, burden, and hole
depth. The test setup was placed at different monitoring locations (distances) every day to
Figure 6. Installation of test bed in Mine-A.
Figure 7. Recorded PPV using accelerometer based test bed at 600 distance.
o_~
08
-
07
"'
--06
e
e
0'5
'-'
c
0_4
....
03
c:J
0
0_2
~
>
01
C)
20
Time (ms)