3
CASE STUDY 1—
SIZING OF MINING PHASES
One of the stages that consumes the most analysis time and
is among the most critical is the pit sizing. This is because
all subsequent analyses are contingent upon this feature.
Consequently, a pre-sizing methodology at the block level
is proposed based on the L&G algorithm of nested or direc-
tional pits, also known as DBS (Depth-Based Search). This
methodology involves conducting a sensitivity analysis on
the phase sizes of the mineral, expressed in tonnages. For
instance, phases ranging from 60 Mt to 110 Mt. Once the
tonnage is defined, it serves as the input data for grouping
the nested or directional pits, forming “pushbacks” based
on the established sensitivity.
Subsequently, a mining plan for each scenario will be
developed, calculating the NPV for each case.
Methodology—Case 1
The methodology carried out for the development of this
case is presented.
A. Review of Phases
B. Generation and Sensitivity of Cones
C. Analysis of the results &Hill of Value
Figure 2. Process optimization strategy (proposed by the
authors)
Results—Case 1
A. Review of Phases
From the current review of phases, the analysis range was
determined to be from 60 to 120 Mt of ore.
B. Generation and Sensitivity of Cones
Based on the analysis range of the phases, the final pit was
obtained, aiming for the target of 247 million tons of ore.
This will serve as the starting point for the various scenarios
to be analyzed.
Once the final pit is obtained, we will group pushbacks
according to the analysis range obtained in point (A).
C. Analysis of Results
Instead of generating various sets of mining pit designs,
which would take a considerable amount of time, the push-
backs from Table 1 were utilized for this purpose, which
are based on cones. This allows for the flexibility in a short
period of time.
Figure 3. Nested pits inside pit final
Table 1. Selection of pushbacks
Case Ore Pushbacks
60 247 5
70 247 4
75 247 4
85 247 3
95 247 3
110 247 3
CASE STUDY 1—
SIZING OF MINING PHASES
One of the stages that consumes the most analysis time and
is among the most critical is the pit sizing. This is because
all subsequent analyses are contingent upon this feature.
Consequently, a pre-sizing methodology at the block level
is proposed based on the L&G algorithm of nested or direc-
tional pits, also known as DBS (Depth-Based Search). This
methodology involves conducting a sensitivity analysis on
the phase sizes of the mineral, expressed in tonnages. For
instance, phases ranging from 60 Mt to 110 Mt. Once the
tonnage is defined, it serves as the input data for grouping
the nested or directional pits, forming “pushbacks” based
on the established sensitivity.
Subsequently, a mining plan for each scenario will be
developed, calculating the NPV for each case.
Methodology—Case 1
The methodology carried out for the development of this
case is presented.
A. Review of Phases
B. Generation and Sensitivity of Cones
C. Analysis of the results &Hill of Value
Figure 2. Process optimization strategy (proposed by the
authors)
Results—Case 1
A. Review of Phases
From the current review of phases, the analysis range was
determined to be from 60 to 120 Mt of ore.
B. Generation and Sensitivity of Cones
Based on the analysis range of the phases, the final pit was
obtained, aiming for the target of 247 million tons of ore.
This will serve as the starting point for the various scenarios
to be analyzed.
Once the final pit is obtained, we will group pushbacks
according to the analysis range obtained in point (A).
C. Analysis of Results
Instead of generating various sets of mining pit designs,
which would take a considerable amount of time, the push-
backs from Table 1 were utilized for this purpose, which
are based on cones. This allows for the flexibility in a short
period of time.
Figure 3. Nested pits inside pit final
Table 1. Selection of pushbacks
Case Ore Pushbacks
60 247 5
70 247 4
75 247 4
85 247 3
95 247 3
110 247 3