NSR Factors Calculation Example Author Upda Update ted d
George McIsaac, Ph.D., ing., P.Eng Marc March h 3, 3, 201 2011 1
Spre Spread adsh shee eett des descri cribi bing ng the the ste steps ps for the the cal calcu cula lati tion on of the the Net Net Smel Smelte terr Retu Return rn and and NSR NSR facto factors rs for for cop cop copper and a zinc flotation circuit In this example, example, detaile detailed d calculations calculations are are done for for estimating estimating the NSR factors factors of each metal metal sold for for ea overall NSR factors of each metal is then calculated and the value of the ore is estimated. The mill sells the copper concentrate to two smelters, 35% to Smelter A and 65% to Smelter B and all the zinc concentrate is sold to Smelter C
This spreadsheet spreadsheet is is provided provided as an educatio educational nal tool and is believed believed to to be free of of error used as an example of how to calculate a Net Smelter Return. The author will not be impro improper per use use or or abus abuse, e, or for errors errors resul resulti ting ng from from its its appli applicat catio ion. n. The user user is is enco encour ur principles described here and to develop his or her own spreadsheet. Worksheet met bal
Description met metallurgi rgical ba balance: es estima timattion of of qu quantities an and qu quality of th the co co from a given mill feed.
individual smelters
estimation of the NSR factors for each metal sold to the smelters
NSR factors
estimat estimation ion of the the overall overall NSR factors factors for each each metal metal.. Also, Also, sens sensiti iti factors as a function of metal prices
NSR
Estimation of the value of the ore.
flowsheet
flowsheet of ore and concentrates
per-zinc ore sent to a mill with a
h concentrate and smelter. The
s. It is intended to be held responsible for its ged to understand the
ncentrates produced
ity of the NSR
Tailings
Cu Zn Au
Copper Concentrate Smelter A Smelter B Zinc Concentrate
Smelter C
Metallurgical Balance
Tonnes
Cu (%) (tonnes)
Au (g/t) (ounces)
275,000
2.32% 6,380
2.55 22,546
85%
73%
21% 5,423
19.93 16,549
Mill Feed
Grades Metal Contained Copper Concentrate Mill Recovery
Tonnes of ore per tonne of concentrate Grades Metal Contained
10.65 25,824
Zinc Concentrate Mill Recovery
Tonnes of ore per tonne of concentrate Grades Metal Contained
15% 10.35 26,571
3.96 3,382
Zn (%) (tonnes) 5.69% 15,648
90%
53% 14,083
Copper concentrate sold to Smelter A Copper Gold Tonnes of Conc. 25,824 tonnes Metal in Conc. 5,423 tonnes Metal per Tonne of Conc. 0.21 tonnes 463 Lbs
16,549 ounces 0.64 ounces 19.9 grams
Copper concentrate sold to Smelter B Copper Gold 25,824 5,423 0.21 463
tonnes tonnes tonnes Lbs
16,549 ounces 0.64 ounces 19.9 grams
Zinc Concentrate sold to Smelter C Zinc Gold 26,571 14,083 0.53 1169
tonnes tonnes tonnes Lbs
3,382 0.13 4.0
ounces ounces grams
24.26
Lbs
2.5
grams
24.26
Lbs
2.5
grams
0
Lbs
1
grams
Payable Metals
439
Lbs
17.4
grams
439
Lbs
17.4
grams
1169
Lbs
3.0
grams
Metal Price Value of Metal
1.50 658
$ / lb $ / t. conc.
$925 518
$ / oz $ / t. conc.
1.50 658
$ / lb $ / t. conc.
$925 518
$ / oz $ / t. conc.
0.50 584
$ / lb $ / t. conc.
Metal Deduction
Copper concentrate sold to Smelter A Copper Gold 658 $ / t. conc. 518 $ / t. conc.
Value of Metal
Copper concentrate sold to Smelter B Copper Gold 658 $ / t. conc. 518 $ / t. conc.
$925 88
$ / oz $ / t. conc.
Zinc Concentrate sold to Smelter C Zinc Gold 584 $ / t. conc. 88
$ / t. conc.
Deduction and Charges
Treatment Charge (T/C) Transport Loading & Representation Penalties (As, Sb, Bi, Hg) Price Participation Subtotal Deductions Refining Charges (R/C) Value After Deductions and Refining
tonnes of ore per ton. conc.
75 34 5 0 0 114
$ / t. conc. $ / t. conc. $ / t. conc. $ / t. conc. $ / t. conc. $ / t. conc.
0.075 33
$ / lb $ / t. conc.
511
$ / t. conc.
10.65
Value per tonne of Ore
48.01
Grade of Ore
2.32%
NSR Factor
20.69
6 3
$ / oz $ / t. conc.
515
$ / t. conc.
10.65 $ / t. ore
$/%
48.37
80 45 5 0 0 130
$ / t. conc. $ / t. conc. $ / t. conc. $ / t. conc. $ / t. conc. $ / t. conc.
0.08 35
$ / lb $ / t. conc.
493
$ / t. conc.
10.65 $ / t. ore
46.30
2.55
g/t
2.32%
18.97
$/g
19.96
6 3
$ / oz $ / t. conc.
515
$ / t. conc.
10.65 $ / t. ore
$/%
135 26 3 0 0 164
$ / t. conc. $ / t. conc. $ / t. conc. $ / t. conc. $ / t. conc. $ / t. conc.
0 0
$ / lb $ / t. conc.
420
$ / t. conc.
10.35
48.37
$ / t. ore
40.61
2.55
g/t
5.69%
18.97
$/g
7.14
6 3
$ / oz $ / t. conc.
85
$ / t. conc.
10.35 $ / t. ore
$/%
8.18
$ / t. ore
2.55
g/t
3.21
$/g
NSR Factors Concentrate
Smelter
Relative sales
Copper ($ / % Cu)
Gold ($/gram)
Copper
A
35%
20.69
18.97
Copper
B
65%
19.96
18.97
100%
20.22
18.97
Copper Zinc
C
100%
Total NSR factors
20.22
Zinc ($ / % Zn)
3.21
7.14
22.17
7.14
Sensitivity to metal prices Copper base price Copper price ($/lb)
$1.00 $1.25 $1.50 $1.75 $2.00 $2.25 $2.50
Gold base price Gold price ($/oz)
700 725 750 775
$1.50
$/lb
) $35.00 % / $30.00 $ ( r o t $25.00 c a f $20.00 R S N$15.00 r e p $10.00 p o C
NSR factor ($/%) $20.22 $11.34 $15.78 $20.22 $24.66 $29.10 $33.54 $37.98
$925 NSR factor ($/%) $22.17 $16.72 $17.33 $17.93 $18.54
$40.00
Copper
$5.00
$0.00 $1.00
$1.50
$2.00
Copper Price ($/lb)
($/oz)
$30.00 $27.50 ) $25.00 m a r g / $22.50 $ ( r
Gold
$2.50
800 825 850 875 900 925 950 975 1,000 1,025 1,050
Zinc base price
$19.14 $19.75 $20.36 $20.96 $21.57 $22.17 $22.78 $23.39 $23.99 $24.60 $25.20
$0.50
t $20.00 c a f R S N$17.50 d l o G
$15.00 $12.50 $10.00 $700
$800
$900
$1,000
$1,100
Gold price ($/oz)
($/lb) $18.00
Gold price ($/oz)
$0.40 $0.50 $0.60 $0.70 $0.80 $0.90 $1.00
NSR factor ($/%) $7.14 $5.15 $7.14 $9.12 $11.11 $13.09 $15.08 $17.06
$16.00
) %$14.00 / $ ( $12.00 r o t $10.00 c a f R $8.00 S N $6.00 c n i $4.00 Z
Zinc
$2.00
$0.00 $0.40
$0.60
$0.80
Zinc price ($/lb)
$1.00
Value of Ore Copper
Gold
Zinc
Mill feed grade
2.32%
2.55
g/t
5.69%
NSR Factors
20.22
$/%
22.17
$/g
7.14
$/%
Value per tonne of ore
46.90
$ / t.
56.54
$ / t.
40.61
$ / t.
Net Smelter Return
144.06 $ / tonne
