3. Project Statement
Design a mineral processing circuit that will liberate the
most and/or maximize the concentration of gold from
Barrick’s Goldstrike dam tailings and create a flowsheet of
the circuit.
Determine the net present value (NPV) of the total amount
of gold that will be liberated and/or concentrated
Calculate an estimated initial rate of return (IRR) of the
process.
4. Quick Facts
• North Block Dam is one of
the largest rockfill tailings
dam in the world
• Goldstrike mine can process
30,000 tones of gold ore per
day
• 170 million tones of tailings
stored in the North Block
Dam
5. Design Approach
Determine a base line analysis of tailings
• Current grade and particle sizes
• Mineralogy
• Liberation Fraction
Concentrate the tailings and analyze results
• Concentration methods may be froth flotation, magnetic and gravity
separation
• Use atomic absorption spectroscopy (AAS) to determine the grade
after each method
• Fire assays done as often as AAS to confirm results
Design flowsheet and determine implications
• NPV and IRR.
6. Completed Results
Mineralogy
• Mostly silicates, magnetic component is maghemite
Initial grade of tailings
• Grade 0.038 Toz/ton Gold
• 6.46 million Toz gold present, current value about $8.4 billion
Gravity separation
• Wave table was used
• About 2000 grams of tailing were processed
• Only about 90 grams of concentrates recovered
• Grade of concentrates were lower than initial grade
7. Results continued
Froth Floation
• Targeted towards carbonaceous material
• 4 tests: Natural, Frother , Oleic Acid, and Frother + Oleic acid
• All surfactants were added at 0.268 lbs/ton
• Only Oleic acid test had gold, but flake was too small to weigh
Magnetic separation
• Targeted 3-5 wt% - attained 7 wt%
• Fire assay 0.48 Toz/ton Gold, 88% recovery
• Contact at Barrick, Wet magnetic separation results: 0.2 Toz/ton
8. Costs
Annual
• Autoclave and acid
leach
• Facility and dredger
horse power
• Maintenance
• Salaries
• Lighting and AC
• Power and horse
power for dryer (dry
process)
Profit
Annual
• Gold
Initial
• Facility
construction
• Dredger
• Fluidized bed dryer
(dry process)
9. Economic calculations for Dry process
Initial Costs $ Annual costs $ Annual profits $
Facity construction 210000000 Autoclave and acid 70956000 Gold 368971200
Dredger 2000000 Facitity's hp 470327.8233
Fluid bed dryer 21875000 personel salaries 1200000
Dredger hp 2660958.048
maintenance 1084629.706
Lighting 117761.28
AC 3751392.505
Dryer hp 39193.98527
Dryer power 20440000000
Totals 233875000 20520280263 368971200
NPV -$165,000,000,000.00
IRR -5.27E+21%
10. Economic calculations for Wet process
Initial Costs $ Annual costs $ Annual profits $
Facity construction 210000000 Autoclave and acid 70956000 Gold 153738000
Dredger 2000000 Facitity's hp 470327.8233
personel salaries 1200000
Dredger hp 2660958.048
maintenance 983181.1769
Lighting 117761.28
AC 3751392.505
Totals 212000000 80139620.83 153738000
NPV $390,000,000.00
IRR 33.1%
11. Economic details and assumptions
discount rate (I) 0.05
number of years 10.78132927
$/kWh 0.06
operates 80% of year 0.8
Tailings (tonage/day) 54000
Concentrates wt%/100 0.05
kW/hp 0.745699872
personel 8
ore grade gold (tOz/ton) wet 0.2
gold recovery %/100 0.75
gold price $/troy 1300
Facitity's hp 1500
Dredger hp 8486.5
autoclave & acid $ /ton 90
personel salaraies/year 150000
Maintenance %total cost/100 0.05
AC power kW based on square footage 8921.690699
lighting power consumption ($/year) 117761.28
square footage 2178000
dryer hp 5
Dryer Power BTU 1E+12
BTU/ton coal 24000000
$/ton coal 70
ore grade gold (tOz/ton) dry 0.48
15. Tasks to Complete
• Complete and turn in individual assignments
• Finish design paper
• Conclude editing of the video
16. What we would have done differently
• Spend more time on froth flotation
-Ignore carbonaceous material
-Focus on creating a two-three stage flotation for maghemite
• Try to perform a wet magnetic separation test
