The Journal of Explosives Engineering - July/August 2022 - 10
Figure 4. Mining sequence: (a) presplit shot prior to blasting for the 4th bench. (b) 4th bench removed down to elevation floor in underground
mine. (c) 4th bench above portals drilled and epoxied to increase strength of roof beam. (d) Portals advanced to final wall.
Table 2. Typical surface blast design.
Figure 5. (a): Schematic plan view showing the pre-blasting location of the portals to the final wall;
(b,c): burn shot holes drilled from outside to inside.
Mining Sequence
The surface mining sequence was as follows: The first
bench was first removed by digging. The second and third
benches were removed by blasting. A presplit shot was done
prior to blasting for the 4th bench. The 4th bench and the
presplit shot are shown in figure 4-a. The presplit shot used a
hole diameter of 3.5 in (9 cm), a spacing of 3 ft (0.9 m), and
15 lbs (6.8 kg) of explosives per hole (10 holes/delay). After
the presplit shot, the 4th bench was removed down the eleva10
tion
of floor in underground mine (figure 4-b). The blasthole
diameters were systematically reduced from 6.5 in (16.5 cm)
to 3.5 in (9 cm) as the blasting neared the underground mine.
Table 2 summarizes typical blast design parameters employed
in surface blasting. The bench above the future portals were
drilled and epoxied to increase strength of roof beam (figure
4-c), and finally, portals were advanced to the final wall
starting with M13 followed by M15 (figure 4-d). M17 has
currently not been extended. Figure 5-a shows a schematic
plan of the pre-blasting relation of M13, M15 and M17 with
The Journal of Explosives Engineering
July/August 2022
The Journal of Explosives Engineering - July/August 2022
Table of Contents for the Digital Edition of The Journal of Explosives Engineering - July/August 2022
From the Executive Director
Crack Displacement and Vibration Measurement of an Underground Portal
Product Spotlight
Industry News
Calendar of Events
Explosives, 100 Years Ago, More or Less
Chapter News
Blasting for Rescue Applications
29th Annual Photo Contest
Safety Talk
The Journal of Explosives Engineering - July/August 2022 - Intro
The Journal of Explosives Engineering - July/August 2022 - Cover1
The Journal of Explosives Engineering - July/August 2022 - Cover2
The Journal of Explosives Engineering - July/August 2022 - 1
The Journal of Explosives Engineering - July/August 2022 - 2
The Journal of Explosives Engineering - July/August 2022 - 3
The Journal of Explosives Engineering - July/August 2022 - From the Executive Director
The Journal of Explosives Engineering - July/August 2022 - 5
The Journal of Explosives Engineering - July/August 2022 - Crack Displacement and Vibration Measurement of an Underground Portal
The Journal of Explosives Engineering - July/August 2022 - 7
The Journal of Explosives Engineering - July/August 2022 - 8
The Journal of Explosives Engineering - July/August 2022 - 9
The Journal of Explosives Engineering - July/August 2022 - 10
The Journal of Explosives Engineering - July/August 2022 - 11
The Journal of Explosives Engineering - July/August 2022 - 12
The Journal of Explosives Engineering - July/August 2022 - 13
The Journal of Explosives Engineering - July/August 2022 - 14
The Journal of Explosives Engineering - July/August 2022 - 15
The Journal of Explosives Engineering - July/August 2022 - Product Spotlight
The Journal of Explosives Engineering - July/August 2022 - 17
The Journal of Explosives Engineering - July/August 2022 - Industry News
The Journal of Explosives Engineering - July/August 2022 - 19
The Journal of Explosives Engineering - July/August 2022 - Calendar of Events
The Journal of Explosives Engineering - July/August 2022 - 21
The Journal of Explosives Engineering - July/August 2022 - Explosives, 100 Years Ago, More or Less
The Journal of Explosives Engineering - July/August 2022 - 23
The Journal of Explosives Engineering - July/August 2022 - 24
The Journal of Explosives Engineering - July/August 2022 - 25
The Journal of Explosives Engineering - July/August 2022 - Chapter News
The Journal of Explosives Engineering - July/August 2022 - 27
The Journal of Explosives Engineering - July/August 2022 - Blasting for Rescue Applications
The Journal of Explosives Engineering - July/August 2022 - 29
The Journal of Explosives Engineering - July/August 2022 - 30
The Journal of Explosives Engineering - July/August 2022 - 31
The Journal of Explosives Engineering - July/August 2022 - 32
The Journal of Explosives Engineering - July/August 2022 - 33
The Journal of Explosives Engineering - July/August 2022 - 34
The Journal of Explosives Engineering - July/August 2022 - 35
The Journal of Explosives Engineering - July/August 2022 - 29th Annual Photo Contest
The Journal of Explosives Engineering - July/August 2022 - 37
The Journal of Explosives Engineering - July/August 2022 - Safety Talk
The Journal of Explosives Engineering - July/August 2022 - 39
The Journal of Explosives Engineering - July/August 2022 - 40
The Journal of Explosives Engineering - July/August 2022 - Cover3
The Journal of Explosives Engineering - July/August 2022 - Cover4
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