290
It is observed a significant reduction on the variability of grades produced by the mine
using the scale of prioritization of the stopes, especially in the first three years of operation
(Figure 4a). In addition, changes are observed in the production of metallic zinc by the mine
since there are changes in variability between rich and poor regions.
The net present value (NPV) observed for the prioritized scenario presents a result, approximately, 5% above that observed for a scenario without prioritization.
It has historically been observed in this mine that, for more stable mill head grades, the ore
processing plant presents significantly higher recovery results and better concentrate specifications. Among the several factors that explain this behavior, is the adequate adjustment of
the equipment and systems of the plant to the type of ore processed.
Due to this, it was simulated the impact that a more controlled planning regarding the
grade variability can have on the metallurgical recovery of the plant and, consequently, on
the financial result.
Figure 5 shows the simulated cash flow results for increments in zinc recovery up to 10%
over its average value used in production planning. As can be seen, increases in metallurgical
recovery through more stabilized feed would represent significant financial gains.
4 CONCLUSIONS
There are several studies already carried out in mines, especially in open pit mines, regarding
the simulation of grades. This study differs in quantifying the uncertainty not only in the
Figure 4. (a) variability of the grades of the stopes. (b) production of metal contained.
Figure 5. Financial gains due to mill feed stabilization.
....
; : : : J\ ..1\r
_A
i o.so
-" ar l\ K ~
rJ"\
i ::: .' ·~ l~ '~'/llJ \..fw1"~,~ \
a o.zo
0,10
o.oo
~
> c..
2
.E
"' "' "' "'
b
.E
rme (month)
~Without_Prior.
With_ Prior.
16
14
12
10
8
6
I
I
4
2
0
0
1
2
3
4
T'me(month)
~Withovt_Prtor.
With_Prior.
5
6
7
8
9
Increase in processing plant recovery(%)
10
It is observed a significant reduction on the variability of grades produced by the mine
using the scale of prioritization of the stopes, especially in the first three years of operation
(Figure 4a). In addition, changes are observed in the production of metallic zinc by the mine
since there are changes in variability between rich and poor regions.
The net present value (NPV) observed for the prioritized scenario presents a result, approximately, 5% above that observed for a scenario without prioritization.
It has historically been observed in this mine that, for more stable mill head grades, the ore
processing plant presents significantly higher recovery results and better concentrate specifications. Among the several factors that explain this behavior, is the adequate adjustment of
the equipment and systems of the plant to the type of ore processed.
Due to this, it was simulated the impact that a more controlled planning regarding the
grade variability can have on the metallurgical recovery of the plant and, consequently, on
the financial result.
Figure 5 shows the simulated cash flow results for increments in zinc recovery up to 10%
over its average value used in production planning. As can be seen, increases in metallurgical
recovery through more stabilized feed would represent significant financial gains.
4 CONCLUSIONS
There are several studies already carried out in mines, especially in open pit mines, regarding
the simulation of grades. This study differs in quantifying the uncertainty not only in the
Figure 4. (a) variability of the grades of the stopes. (b) production of metal contained.
Figure 5. Financial gains due to mill feed stabilization.
....
; : : : J\ ..1\r
_A
i o.so
-" ar l\ K ~
rJ"\
i ::: .' ·~ l~ '~'/llJ \..fw1"~,~ \
a o.zo
0,10
o.oo
~
> c..
2
.E
"' "' "' "'
b
.E
rme (month)
~Without_Prior.
With_ Prior.
16
14
12
10
8
6
I
I
4
2
0
0
1
2
3
4
T'me(month)
~Withovt_Prtor.
With_Prior.
5
6
7
8
9
Increase in processing plant recovery(%)
10