GOLDEN SUNLIGHT

May 2011May 2011

Barrick - Golden Sunlight MineMine Design, Operation and

Closure Conference

Golden SunlightMine

Golden Sunlight Mine

Golden Sunlight Mine

East Waste Rock Dump Complex

Tailings Impoundment #2

Tailings Impoundment #1

West Waste Rock Dump Complex

Mineral HillOpen Pit

I-90

Hwy 69

Hwy 2

Mill Site

Water Management

During OperationUse as makeup water for mill circuitMajor sources

• Pit• Tailings Impoundment #1 containment wells

Water Management

ClosurePump – Treat - DischargeMajor sources

• Pit• Tailings Impoundment #1 containment wells• Tailings Impoundment #2 drain-down

Water Types

Pit Water–ARD signature

• Low pH, sulfate, iron, trace metals, and TDS

Tailings Impoundment Waters–Process water residuals

• Cyanide, thiocyanate, nitrate, ammonia, and TDS• Slight signature of neutralized ARD

Treatment

Pit Water–Active HDS type treatment (pH adjustment, metals precipitation), possibly polishing for TDS removal.

Tailings Impoundment Water–Active biological treatment (aerobic and anaerobic), possibly followed by HDS and polishing for TDS removal.

Biological Treatment Desired Reactions:Aerobic

CN + Bacteria HCO3 + NH3

SCN + OH + Bacteria SO4 + HCO3 + NH3

NH3 + Bacteria NO2 + Bacteria NO3 (nitrification)

AnaerobicNO3 + CH3OH + Bacteria CO2 + N2 (g) + OH

(denitrifaction)

Adsorption and Absorption of Heavy Metals

Passive Biological Treatment

Acknowledgementso Jim Whitlock – Whitlock and Associates

oChris Nelson – Barrick Golden Sunlight Mine

oRory Tibbals and Shannon Dunlap

oRick Henderson and Tom Monfortan – Barrick Golden Sunlight Mine

oKathy Gallagher - SPSI

Pilot Plant Testing Down flow columns constructed in GSM mill facility

- 42 inch diameter and 14 foot height

Counter current air flow (convective)

Inert rock media used (1/4 - 5/8 inch nominal size)

Tailings Impoundment #2 reclaim water used for testing

Flow rate - 3 gallons/day/ft2

Inoculated

Pilot Test Results 96 % removal of cyanide

98-99% removal of thiocyanate

Nearly complete nitrification

Anaerobic column used to effectively denitrify

98-99% removal of copper (19 ppm to 1 ppm)

Slight decrease in TDS

pH relatively unchanged at approximately 8 s.u.

Heap Treatment• One acre limestone based pad on a synthetic liner

• Limestone - 20% > 1.5”, 50% > 1” and 70% < ¾”

• Buried drip line distribution system

• Counter current convection air in heap

• Flow rate - 3 gallons/day/ft2

• Soda ash (alkalinity) and phosphate added to influent

• Source water - T1 containment well water

Heap Test Results

0

50

100

150

200

250

300

350

12/19/2002 12/19/2003 12/19/2004 12/19/2005 12/19/2006 12/19/2007 12/19/2008

Thio

cyan

ate

(mg/

L)

Heap Test - Thiocyanate

Influent Effluent

Heap Test Results

0

5

10

15

20

25

30

35

12/19/2002 12/19/2003 12/19/2004 12/19/2005 12/19/2006 12/19/2007 12/19/2008

Total Cyanide

 (mg/L)

Heap Test – Total Cyanide

Influent Effluent

Heap Test Results

0

5

10

15

20

25

30

35

40

45

50

12/19/2002 12/19/2003 12/19/2004 12/19/2005 12/19/2006 12/19/2007 12/19/2008

Am

mon

ia (

mg/

L -

N)

Heap Test - Ammonia

Influent Effluent

Heap Test Results

0

5

10

15

20

25

30

35

40

45

50

1/9/2003 1/9/2004 1/9/2005 1/9/2006 1/9/2007 1/9/2008 1/9/2009

Nit

rate

(m

g/L

-N

)

Heap Test - Nitrate

Influent Effluent

Heap Test Results

0

5

10

15

20

25

3/18/2003 3/18/2004 3/18/2005 3/18/2006 3/18/2007 3/18/2008 3/18/2009

Cop

per

(mg/

L)

Heap Test - Copper

Influent Effluent

Heap Test Results

0

0.002

0.004

0.006

0.008

0.01

0.012

0.014

0.016

0.018

0.02

4/19/2004 4/19/2005 4/19/2006 4/19/2007 4/19/2008 4/19/2009

Ars

enic

(m

g/L)

Heap Test - Arsenic

Influent Effluent

Heap Test Results

1500

2000

2500

3000

3500

4000

4500

3811

0

3817

1

3823

3

3829

4

3835

5

3841

4

3847

5

3853

6

3859

8

3865

9

3872

0

3877

9

3884

0

3890

1

3896

3

3902

4

3908

5

3914

4

3920

5

3926

6

3932

8

3938

9

3945

0

3951

0

3957

1

3963

2

3969

4

3975

5

3981

6

3987

5

3993

6

3999

7

4005

9

4012

0

TDS

(mg/

L)

Heap Test - Total Dissolved Solids

Influent Effluent

Heap Test Results

Heap treatment can significantly reduce cyanide and thiocyanate concentrations

Heap treatment can reduce metal and metalloid concentrations

A single stage heap did not demonstrate complete nitrification

Short circuiting due to plugged drip line filters was a problem

Temperature effects on small heap reduced performance, particularly for nitrification

Single stage heap could not meet WQ standards

Heap Treatment

Larger heaps could mitigate temperature effects

A second stage heap could likely remove more cyanide and thiocyanate as wells have complete nitrification

TDS is a problem – some sulfate could be removed in an anaerobic denitrification treatment step

Heap treatment could reduce phytotoxicity for land application

Heap treatment has the potential for a low capital and operating cost water management tool

Questions ?

(None – Thank You)

Jim Whitlock

“A number of research people have tried to make this process(es) work without much success, probably because it is art as well as science. ”

“If your audience wants to contact me with questions, that is fine as well.”