The Journal of Explosives Engineering - March/April 2013 - 34
Figure 7. Cross section view of highwall with 7.6 m (25 ft) catch bench and angled drill holes.
Figure 8. Cross section of typical highwall with angled drill holes after catch bench removed.
Implementation of Pyrotechnic Cast Blast
The first full height cast blasts were quite complicated
due to a 7.6 m (25 ft) wide catch bench left between the
old low and high cover benches. Due to safety concerns,
Simplot was only able to drill, load, and blast approximately
9.15 m (30 ft) from the base of the high cover highwall.
This made the drill design much more complicated than
anticipated requiring a 30 degree angle hole with a bottom
load in order to break the toe of the highwall. The A row of
the shot was drilled at 30 degrees, the B row at 25 degrees,
and C - J rows at 20 degrees. The pattern was basically a
rectangular pattern with a burden and spacing of 6.7 x
7.9 m (22 x 26 ft) with the A row placed on a staggered
pattern between the B and C rows approximately 3.048 m
(10 ft) behind the B row holes. See figure 7. Careful consideration was given for the loading of the A holes including a bottom load and middle stemming to prevent energy
escape near the catch bench.
34
Once the low cover bench and the high cover benches
were all caught up into one bench eliminating the benched
highwall, the drill designs became more basic with all rows
angled at 20 degrees as illustrated in figure 8. Simplot was
then also able to drill a staggered pattern with a burden and
spacing of 6.7 x 7.9 m (22 x 26 ft) rather than a rectangular
drill hole pattern. Figure 9 shows a typical cross section of
the muck pile produced by a pyrotechnic cast shot.
Electronic Detonator Cast Blast
The final step in the conversion process was the change
from pyrotechnic detonators to electronics. Our best typical pyrotechnic blasts used 17 ms hole to hole delays and
increasing approximately 100 ms row-to-row delays.
The first electronic detonator cast blast enabled the
mine to use 12 ms hole-to-hole delays down the rows
while increasing the row-to-row delay at 125 ms each row.
This change in timing and the accuracy of the electronic
The Journal of Explosives Engineers
March/April 2013
http://www.isee.org
The Journal of Explosives Engineering - March/April 2013
Table of Contents for the Digital Edition of The Journal of Explosives Engineering - March/April 2013
Call for Papers
From the President
Highlights of the 39th Annual Conference in Fort Worth, Texas
Chapter News
Industry News
Calendar of Events
20th Annual Photo Contest Winners
Explosives, 100 Years Ago, More or Less
Conversion from Two-Pass Overburden Removal to Cast Blasting at Simplot Phosphates
The Journal of Explosives Engineering - March/April 2013 - cover1
The Journal of Explosives Engineering - March/April 2013 - cover2
The Journal of Explosives Engineering - March/April 2013 - Call for Papers
The Journal of Explosives Engineering - March/April 2013 - 2
The Journal of Explosives Engineering - March/April 2013 - 3
The Journal of Explosives Engineering - March/April 2013 - From the President
The Journal of Explosives Engineering - March/April 2013 - 5
The Journal of Explosives Engineering - March/April 2013 - Highlights of the 39th Annual Conference in Fort Worth, Texas
The Journal of Explosives Engineering - March/April 2013 - 7
The Journal of Explosives Engineering - March/April 2013 - 8
The Journal of Explosives Engineering - March/April 2013 - 9
The Journal of Explosives Engineering - March/April 2013 - 10
The Journal of Explosives Engineering - March/April 2013 - 11
The Journal of Explosives Engineering - March/April 2013 - 12
The Journal of Explosives Engineering - March/April 2013 - 13
The Journal of Explosives Engineering - March/April 2013 - Chapter News
The Journal of Explosives Engineering - March/April 2013 - 15
The Journal of Explosives Engineering - March/April 2013 - 16
The Journal of Explosives Engineering - March/April 2013 - 17
The Journal of Explosives Engineering - March/April 2013 - Industry News
The Journal of Explosives Engineering - March/April 2013 - 19
The Journal of Explosives Engineering - March/April 2013 - Calendar of Events
The Journal of Explosives Engineering - March/April 2013 - 21
The Journal of Explosives Engineering - March/April 2013 - 20th Annual Photo Contest Winners
The Journal of Explosives Engineering - March/April 2013 - 23
The Journal of Explosives Engineering - March/April 2013 - Explosives, 100 Years Ago, More or Less
The Journal of Explosives Engineering - March/April 2013 - 25
The Journal of Explosives Engineering - March/April 2013 - 26
The Journal of Explosives Engineering - March/April 2013 - 27
The Journal of Explosives Engineering - March/April 2013 - Conversion from Two-Pass Overburden Removal to Cast Blasting at Simplot Phosphates
The Journal of Explosives Engineering - March/April 2013 - 29
The Journal of Explosives Engineering - March/April 2013 - 30
The Journal of Explosives Engineering - March/April 2013 - 31
The Journal of Explosives Engineering - March/April 2013 - 32
The Journal of Explosives Engineering - March/April 2013 - 33
The Journal of Explosives Engineering - March/April 2013 - 34
The Journal of Explosives Engineering - March/April 2013 - 35
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The Journal of Explosives Engineering - March/April 2013 - 37
The Journal of Explosives Engineering - March/April 2013 - 38
The Journal of Explosives Engineering - March/April 2013 - 39
The Journal of Explosives Engineering - March/April 2013 - 40
The Journal of Explosives Engineering - March/April 2013 - cover3
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