1. Resource recovery at the Berkeley Pit mine in Butte, MT resulted in the production of 37 million pounds of copper over 9 years of cementation. 2. Artificial mixing of the pit water changed the lake's limnology from meromictic to holomictic, inducing oxidation of dissolved iron and precipitation of secondary ferric compounds that decreased dissolved copper, iron, arsenic, and phosphorus concentrations. 3. Total acidity in the pit water decreased 25-30%, potentially significantly reducing long-term water treatment costs. Resource recovery is a cost-effective approach that can help reduce treatment costs and support more sustainable mine closure.

1. Resource Recovery – Case Study
Turning Complete Liability Into Economic
Opportunity
Nicholas J. Tucci
2016 SME Conference
Phoenix, AZ

2. – Direct Precipitation
• Addition of reagent forces metal solubility and precipitation.
– Solvent Extraction (Liquid-liquid extraction)
• Extraction from one aqueous solution into another immiscible organic solvent.
• Three phases: extraction, scrubbing and stripping.
– Ion Exchange
• Exchange of ions between two electrolytes or between an electrolyte solution
and a complex.
• Widely used technology in waste water treatment and hydro-metallurgical
processing.
December 16, 2016Resource Recovery, Tucci Page 2
Resource Recovery: Selective extraction of economically valuable
minerals from mine waste for a specific next use purpose.

3. Case Study – Berkeley Pit
– Porphyry copper mine in Butte, MT
– Dewatering pumps turned off in 1982
– Pit-lake began forming in 1983
– Main water inputs
• Groundwater from surrounding
underground mines
• Surface water diversions
• Precipitation < Evaporation
– Critical lake level = 5,410’
• Expected to reach C.L. > 2023
• Remedy – in perpetuity HDS lime
treatment
Berkeley Pit, 1982
5410’ - Critical Water Level
2013 Water Level
5410’ -Critical Water Level
2013 Water Level
Berkeley Pit, 2013
Minimum Clearance = 100’
-Source: MBMG (2011)

4. Berkeley Pit lake
Tailings Pond
Continental Pit
(active)
Continental Fault
Cementation plant & Horseshoe Bend

5. Cu-plated steel rails in underground mine water
Lexington Tunnel, Butte
Cu2+ + scrap Fe → Fe2+ + Cu
Copper Recovery Process
Process developed in Butte, MT: W. Ledford (1890)
C. Gammons, MT. Tech

6. Cu2+ + scrap Fe → Fe2+ + Cu
Resource Recovery:
Copper Cementation
Over 40 million lbs Cu dissolved in B-Pit prior to recovery
Process is 75 - 90% efficient
Berkeley
Pit-lake
~ 150 ppm Cu
~ 30 ppm Cu

7. December 16, 2016Resource Recovery, Tucci Page 7
– Plant operation: 2004-2013
– 1.3 pit-volumes cycled
through plant.
– Direct: 37 million pounds of
Cu recovered from Berkeley
Pit water.
– Indirect: Significant
improvement of water
quality
Copper Recovery Process
Source: Tucci and Gammons (2015)
Annual recovery of Cu (in tonnes) from cementation plant

8. Effect of Cu Recover on Limnology
Over 47 billion gallons cycled in 9 years
Chronology of the Chemocline
Cu cementation
resumes

9. December 16, 2016Resource Recovery, Tucci Page 9
Water Quality Impacts
~272 million pounds of Fe and 330,000 pounds of As removed in 9 Years
~ 4 months solids collection
Secondary Mineral Precipitation
MBMG, 2011

10. Scavenging of PO4
3-, AsO4
3- by FeIII oxy-hydroxides
time

11. epilimnion
hypolimnion
pit sediment
O2 diffusion
gravitational
settling
Cu cementation
Cu recovery
intake
schwertmannite ← Fe3+ ← Fe2+
Cu2+ + Fe → Fe2+ + Cu
8Fe2+
+ 10H2O + SO4
2-
+ 2O2 = Fe8O8(OH)6SO4(s) + 14H+

12. December 16, 2016Resource Recovery, Tucci Page 12
– 25-30% decrease in total acidity may
result in significant cost savings for
remedy.
Total Acidity
Acidity Vs. TimeOctober, 2002 June, 2012

13. Summary
– 9 years of cementation resulted in the production of 37 million pounds of
copper recovery.
– Artificial mixing caused by continuous pumping changed lake limnology
from a meromictic to holomictic state, induced oxidation of dissolved Fe2+
and caused subsequent precipitation of secondary ferric compounds.
– Dissolved Cu and Fe concentrations have been cut in half
– Dissolved As and P concentrations decreased by an order of magnitude
– Total acidity decreased 25 – 30 percent, resulting in potentially significant
reductions in treatment costs.

14. Future Resource Recovery Potential: Estimated Metal Value in Pit
12/16/2016Resource Recovery, Tucci 14
Metal Average Concentration Mass in Pit Lake Commercial Unit USD/commercial unit Value in Pit
(2012) ug/L lb Feb-16
Al 288173 102,000,000 lb 0.69 $70,380,000
Mn 240570 85,100,000 kg 1.48 $57,249,091
Cd 2050 725,000 lb 0.56 $406,000
Ce 890 315,000 kg 13 $1,861,364
Co 1505 533,000 lb 10.4 $5,543,200
Cu 53643 19,000,000 lb 2.07 $39,330,000
La 250 88,500 kg 10.5 $422,386
Li 254 89,900 ton 6000 $269,700
Ni 1198 424,000 lb 3.68 $1,560,320
Nd 436 154,000 kg 60 $4,200,000
Pr 88 31,200 kg 155 $2,198,182
Rb 47 16,600 100g 1118 $84,415,149
U 723 256,000 lb oxide 34 $24,582
Zn 626706 222,000,000 lb 0.77 $170,940,000
Pd 21.7 3,600 troz 775 $87,432,859
Total $526,232,833

15. Resource recovery analysis is a cost-effective approach that has the potential to
significantly reduce the cost of treatment, and should be considered as a tool in any
life-cycle management plan during mine closure.
Direct cost recovery potential is significant.
Treatment Optimization: resource recovery can improve overall water quality, and
indirectly reduce the costs associated with treatment.
Offers a sustainable approach to mine closure that is often encouraged and
promoted in today’s regulatory environment.
When life hand you lemons……..turning a negative into a positive is often
associated with improved public relations.
December 16, 2016Presentation Title Page 15
A Remedy that Can Pay for Itself – Advantages of Resource Recovery

16. References
Castendyk, D.N., Balistrieri, L.S., Gammons, C.G., and Tucci, N.J. (2015) Modeling and management of pit lake
water chemistry 2: case studies, Applied Geochemistry 57 (2015) 289-307
Duaime, T.E. and Tucci, N.J. (2011) Butte Mine Flooding Operable Unit Water-Level Monitoring and Water-Quality
Sampling 2010 Consent Decree Update, Butte, Montana1982-2010. Montana Bureau of Mine and Geology
Open File Report 609.
Tucci, N.J. and Gammons, C.G. (2015) Influence of Copper Recovery on the Water Quality of the Acidic
Berkeley Pit Lake, Montana, USA, Environmental Science and Technology 49 (2015) 4081-4088
Special thanks to Montana Bureau of Mines and Geology In Butte MT

17. Thank You
Nicholas.Tucci@aecom.com
February 23, 2016
“Pollution is nothing but the resources we are not harvesting. We allow them to be
dispersed because we’ve been ignorant of their value” – R. Buckminster Fuller