5
reclaimed stockpile ore grades. Note that because cut-offs
and stockpile tonnage flows are adjusted to balance ore feed
tonnage with mill capacity, there is no uncertainty in mill
tonnage for this case. This shows up as zero relative stan-
dard deviation for tons in each year. The yearly risk profile
information can be used to identify orebody volumes for
additional infill drilling or other risk mitigation. The size
of the yearly error bars may be helpful to guide conserva-
tive forecast communications to internal and/or external
audiences.
Strategic Options and Key Sensitivities
A series of cases were analyzed to demonstrate the impact
of alternative strategic options on net present value (NPV)
in terms of both expected value and expected risk. Mine
plans were created by deterministic optimization using the
IK models as input (except where noted) with stochastic
evaluation performed using the CS realizations to ensure a
consistent evaluation of all cases:
A. A2 Mill only, no stockpile, with low con-
stant cut-off in all time periods (0.02 oz/ton)
A4 Mill only, no stockpile, best constant cut-off in all
time periods (0.04 oz/ton)
B. Mill only, no stockpile, optimized variable cut-off
over time
C. Mill only, stockpile, optimized variable cut-off over
time
D. Mill +leach, stockpile, optimized variable cut-off
over time
To provide sensitivity perspective to mining shortfalls, the
following comparison cases were also evaluated:
E. Case C with maximum vertical advance rate reduced
from 8 to 6 benches/yr
F. Case C with maximum mining rate reduced from 10
to 8 Mt/yr
For geostatistical &optimization perspective, the following
cases were also evaluated:
Figure 3. Base case mine plan stochastic evaluation dashboard from conditional simulation inputs
reclaimed stockpile ore grades. Note that because cut-offs
and stockpile tonnage flows are adjusted to balance ore feed
tonnage with mill capacity, there is no uncertainty in mill
tonnage for this case. This shows up as zero relative stan-
dard deviation for tons in each year. The yearly risk profile
information can be used to identify orebody volumes for
additional infill drilling or other risk mitigation. The size
of the yearly error bars may be helpful to guide conserva-
tive forecast communications to internal and/or external
audiences.
Strategic Options and Key Sensitivities
A series of cases were analyzed to demonstrate the impact
of alternative strategic options on net present value (NPV)
in terms of both expected value and expected risk. Mine
plans were created by deterministic optimization using the
IK models as input (except where noted) with stochastic
evaluation performed using the CS realizations to ensure a
consistent evaluation of all cases:
A. A2 Mill only, no stockpile, with low con-
stant cut-off in all time periods (0.02 oz/ton)
A4 Mill only, no stockpile, best constant cut-off in all
time periods (0.04 oz/ton)
B. Mill only, no stockpile, optimized variable cut-off
over time
C. Mill only, stockpile, optimized variable cut-off over
time
D. Mill +leach, stockpile, optimized variable cut-off
over time
To provide sensitivity perspective to mining shortfalls, the
following comparison cases were also evaluated:
E. Case C with maximum vertical advance rate reduced
from 8 to 6 benches/yr
F. Case C with maximum mining rate reduced from 10
to 8 Mt/yr
For geostatistical &optimization perspective, the following
cases were also evaluated:
Figure 3. Base case mine plan stochastic evaluation dashboard from conditional simulation inputs