4
Stope Revenue
The revenue calculations shown in Table 4 illustrate how the
stope revenue is calculated. The “payable” factor (95.0%)
is a composite factor used for convenience that incorpo-
rates all items included in the “Rev-g” discussion shown in
Table 2. The value itself is a composite from several recent
projects with which the authors are familiar.
This clearly shows the change in contained value that
occurs between the initial stope design and the revenue
received after all operational factors and off-site expenses
are accounted for.
STOPE COSTS AND CUTOFF GRADE
VALUATION
The cost side of the equations for our example stope is pre-
sented in Table 5. It shows the costs applied for the break-
even and planning costs presented above.
COV at the Mill head grade is the same as the Total
cost per tonne, in our example: $103.00 &$126.90. Since
the mill head grade is always lower than the in situ stope
reserve, a correction must be made to allow for unplanned
stope dilution and recovery.
To make this correction, we calculate the Stope Grade
Factor from Table 4 as follows.
$
$200
181.82
1.100 Stope Grade Factor
R v-g
Rev-g Stope Reserve
e Mill Head
==
Figure 1. Transverse Sublevel Open Stoping
Table 4. Stope Revenue Calculation
Stope
Reserve Dilution
Stope
Inventory
Stope
Recovery
Mill
Head
Shipped
Metal
Payable
(Rev-g)
10.0% 93.0% 90.0% 95.0%
Tonnes 20,000 2,000 22,000 20,460 20,460
Rev-g value $200.00 $-$181.82 $181.82 $181.82
Contained value ($×1,000) $4,000 $-$4,000 $3,720 $3,720 $3,348
$3,180.6
Table 5. Cost Side for Example Stope
Cut-off Value Calculations
Break Even Planning
Operating $/t $/t
Mining 50.00 50.00
Backfill 15.00 15.00
Mine overhead 10.00 10.00
Process +tails 18.00 18.00
Site general and
administrative
10.00 10.00
Sustaining capital $/t $/t
Waste development -
footwall lateral
— 6.00
Waste development -
stope cross-cut
— 6.00
Mobile equipment -
replace and rebuild
— 2.50
Other — —
Subtotal cost per tonne
($/t)
103.00 117.50
Margin (%)0 8.0
Total cost per tonne $103.00 $126.90
COV -Mill Head
(Rev-g $/tonne)
$103.00 $126.90
Stope Grade Factor ×1.100 ×1.100
COV -Stope Neat Line
(Rev-g $/tonne)
$113.30 $139.59
Stope Revenue
The revenue calculations shown in Table 4 illustrate how the
stope revenue is calculated. The “payable” factor (95.0%)
is a composite factor used for convenience that incorpo-
rates all items included in the “Rev-g” discussion shown in
Table 2. The value itself is a composite from several recent
projects with which the authors are familiar.
This clearly shows the change in contained value that
occurs between the initial stope design and the revenue
received after all operational factors and off-site expenses
are accounted for.
STOPE COSTS AND CUTOFF GRADE
VALUATION
The cost side of the equations for our example stope is pre-
sented in Table 5. It shows the costs applied for the break-
even and planning costs presented above.
COV at the Mill head grade is the same as the Total
cost per tonne, in our example: $103.00 &$126.90. Since
the mill head grade is always lower than the in situ stope
reserve, a correction must be made to allow for unplanned
stope dilution and recovery.
To make this correction, we calculate the Stope Grade
Factor from Table 4 as follows.
$
$200
181.82
1.100 Stope Grade Factor
R v-g
Rev-g Stope Reserve
e Mill Head
==
Figure 1. Transverse Sublevel Open Stoping
Table 4. Stope Revenue Calculation
Stope
Reserve Dilution
Stope
Inventory
Stope
Recovery
Mill
Head
Shipped
Metal
Payable
(Rev-g)
10.0% 93.0% 90.0% 95.0%
Tonnes 20,000 2,000 22,000 20,460 20,460
Rev-g value $200.00 $-$181.82 $181.82 $181.82
Contained value ($×1,000) $4,000 $-$4,000 $3,720 $3,720 $3,348
$3,180.6
Table 5. Cost Side for Example Stope
Cut-off Value Calculations
Break Even Planning
Operating $/t $/t
Mining 50.00 50.00
Backfill 15.00 15.00
Mine overhead 10.00 10.00
Process +tails 18.00 18.00
Site general and
administrative
10.00 10.00
Sustaining capital $/t $/t
Waste development -
footwall lateral
— 6.00
Waste development -
stope cross-cut
— 6.00
Mobile equipment -
replace and rebuild
— 2.50
Other — —
Subtotal cost per tonne
($/t)
103.00 117.50
Margin (%)0 8.0
Total cost per tonne $103.00 $126.90
COV -Mill Head
(Rev-g $/tonne)
$103.00 $126.90
Stope Grade Factor ×1.100 ×1.100
COV -Stope Neat Line
(Rev-g $/tonne)
$113.30 $139.59