2
METHODOLOGY
To address the problem, the Capstone Copper – Pinto
Valley mine engineering team and Dyno Nobel engaged to
perform a detailed evaluation of the trim blast designs used
over the years at the operation and conduct field measure-
ments to verify if the performance observed was aligned
with the drilling and blasting plans. The steps taken along
the project entailed the following:
1. Review drilling-and-blasting designs to evaluate
if any immediate opportunities exist to enhance
them and improve fragmentation, and therefore
recovery of the material left on the walls.
2. Collect field data, including drill operators’ feed-
back, to evaluate quality of pre-splitting techniques
and potential influence in the results.
3. Test and assess design alternatives in two benches of
the mine for a period of approximately 6 months.
RESULTS
The results obtained during this project can be summarized
as follows:
1. The review of the trim-blast designs revealed two
main concerns:
a. The low powder factor and resulting potential
and usually observed poor fragmentation on the
top, back side of the blasts, near the highwall (see
coarse material in Figure 2, generated from the
blue circle area of low powder factor in cross-sec-
tion of Figure 3).
b. The proximity of the toes of the trim row hole toes
to the pre-split line of approximately 3ft, or 0.9m
(see pink circles in cross-section of Figure 3).
2. The Capstone Copper Mine Engineering and
DynoConsult teams conducted pre-split drill hole
Figure 1. Visual evidence of the unrecovered material attached to highwall on the South side of the Capstone Copper Pinto
Valley mine (left side) and schematic cross-section illustrating unrecoverable underbreak and reduced catch-benches (right-side)
Figure 2. Coarser fragmentation observed near the wall on the top 45ft (13.7m) of a bench
that has been pre-split down to the full 90ft (27.4m depth). Notice coarser material near the
bench crest
METHODOLOGY
To address the problem, the Capstone Copper – Pinto
Valley mine engineering team and Dyno Nobel engaged to
perform a detailed evaluation of the trim blast designs used
over the years at the operation and conduct field measure-
ments to verify if the performance observed was aligned
with the drilling and blasting plans. The steps taken along
the project entailed the following:
1. Review drilling-and-blasting designs to evaluate
if any immediate opportunities exist to enhance
them and improve fragmentation, and therefore
recovery of the material left on the walls.
2. Collect field data, including drill operators’ feed-
back, to evaluate quality of pre-splitting techniques
and potential influence in the results.
3. Test and assess design alternatives in two benches of
the mine for a period of approximately 6 months.
RESULTS
The results obtained during this project can be summarized
as follows:
1. The review of the trim-blast designs revealed two
main concerns:
a. The low powder factor and resulting potential
and usually observed poor fragmentation on the
top, back side of the blasts, near the highwall (see
coarse material in Figure 2, generated from the
blue circle area of low powder factor in cross-sec-
tion of Figure 3).
b. The proximity of the toes of the trim row hole toes
to the pre-split line of approximately 3ft, or 0.9m
(see pink circles in cross-section of Figure 3).
2. The Capstone Copper Mine Engineering and
DynoConsult teams conducted pre-split drill hole
Figure 1. Visual evidence of the unrecovered material attached to highwall on the South side of the Capstone Copper Pinto
Valley mine (left side) and schematic cross-section illustrating unrecoverable underbreak and reduced catch-benches (right-side)
Figure 2. Coarser fragmentation observed near the wall on the top 45ft (13.7m) of a bench
that has been pre-split down to the full 90ft (27.4m depth). Notice coarser material near the
bench crest