62 • ROCK products • March 2018 www.rockproducts.com
Modern Design in Blasting
Table 1 - Example blast dimensions
Hole Type Burden Subdrill Stemming Hole Length Lb. per hole
Opening Holes
13 ft. 6.5 ft. 13 ft. 46.5 ft. 345 lb.
Production Holes
13 ft. 4 ft. 9 ft. 44 ft. 360 lb.
Table 2 - Example Powder Factor Comparison
Hole Number Explosive Load Volume of Rock Powder Factor
Number 1 holes
345 lb. (1,380 lb. total) 250 cyd 5.52 lb./cyd
Number 2 holes
360 lb. (720 lb. total) 250 cyd 2.88 lb./cyd
Other Holes
360 lb. 250 cyd 1.44 lb./cyd
Figure 3 - Sinking cut firing with electric cap pattern.
Figure 4 - Sinking cut fired with spiral non-electric timing.
The sinking cut in Figure 3
are fired with electric blast-
ing caps in the delay sequence
shown in Figure 1. The sink-
ing cut shown in Figure 4 is
fired using the delay sequence
shown in Figure 2. These delay
sequences both produce good
results because as the number
of row and holes in a row
increase the actual millisec-
onds of time between rows also
increases.
Conclusion
In today's mining industry effi-
cient blasting practices give a
competitive edge and are crit-
ical to successful operations.
Old methods of blasting are no
longer acceptable as competi-
tors are constantly improving
and newer, modern methods
of blasting give better results
and produce a large economic
advantage. While this is pres-
ent in all areas of blasting,
sinking cuts have been lag-
ging behind other aspects of
the production process. This
article outlines methods for
operators to efficiently drop to
new elevations in a cost-effec-
tive and controlled manner.
Dr. Calvin Konya is the president
of Precision Blasting Services,
and Anthony Konya is a project
engineer for the company. They
can be reached at 440-823-2263,
or anthony@idc-pbs.com.