Golden Sunlight Mine Bio-Treatment of Acid Producing...

Golden Sunlight Mine Bio-Treatment of Acid

Producing Waste By

Rory Tibbals Operations Superintendent

Golden Sunlight Mine

• Gold Producing Mine • 2.5 Million Ounces Produced • 20 Year Operation • Ore and All Waste High In Sulfides – Acid Producing • Mitigating Factors

– Semi Arid Environment – Summer Precipitation – Good Soil Characteristics – Little Arsenic, Mercury, Selenium etc.

Site Status

• Mine Nearing Closure

• Sixteen Research and Technology Demonstration Projects

• Two-thirds of Disturbed Area Reclaimed – Over

1000 acres Restored to Wildlife Habitat

• Perpetual Water Treatment Planned and Bonded

Reclaimed West Dump

Reclaimed Acreage

Deer on Reclamation

Some Problem Areas

• Stepan and Midas Springs – Acid Drainage

• Pit Water Quality

• Potential For Waste Rock Acid Drainage

• Potential For Tailings Acid Drainage

• Cyanide Contaminated Groundwater

Project 16A SRB-Driven Sulfide Precipitation

Demonstration

Project Management Dianna Bless - EPA Garth James – MSE

Rory Tibbals – Golden Sunlight Mine

SRB-Driven Sulfide Precipitation Demonstration Project

• Innovative design involves a two-step system • Biological products (H2S and HCO3)

generated in bioreactor by SRB • Biological products in the bioreactor effluent

are mixed with AMD • Bench-scale testing completed at MSE • Field-scale testing at Golden Sunlight Mines


Midas AMD

Settling Pond

SRB Bioreactor

Treated Effluent

Recycle

Nutrients

Sludge Removal


0 1 2 3 4 5 6 7

Jul-01 Nov-01 Feb-02 May-02 Sep-02 Date

pH

In Mid Eff


0.01

0.1

1

10

100

1000

10000


Dis

solv

ed A

lum

inum

(mg/

L)

. In Mid Eff


0.001 0.01

0.1 1

10 100

1000

Jul-01 Nov-01 Feb-02 May-02 Sep-02

Date

Dis

solv

ed C

oppe

r (m

g/L)

.

In Mid Eff


0.1

1

10

100

1000


Dis

solv

ed Ir

on (m

g/L)

. In Mid Eff


0.001

0.01

0.1

1

10

100


Dis

solv

ed Z

inc

(mg/

L)

. In Mid Eff

•Alkalinty and sulfide generation •pH increase •Removal of Al, Cu, Fe, Zn


SRB-Driven Sulfide Precipitation

Water 50% Sulfur 13.7% Sulfide n.d. Sulfate n.d. Carbonate 13.0% Aluminum 6.1% Arsenic n.d. Calcium 9.4% Copper 0.4% Iron 1.1% Magnesium 2.1% Manganese 0.2% Potassium 0.4% Silicon 2.2% Sodium 0.3% Zinc 0.2%

Bioreactor Sludge Analyses

CONCLUSIONS

• The bioreactor worked very effectively at producing alkalinity sufficient to neutralize acid constituents.

• The bioreactor did not experience plugging. • All lost sulfate was turned into sulfur via oxidation. • Sulfate reduction was limited by the oxidation potential of

the contained metals. • Manganese, and to some extent iron reduction, was limited

by oxidation state, reduced forms being more soluble. • Ca, Mg reduction was limited by carbonate production and

carbonate solubility.

Midas Dump

• Midas Dump Built Over Spring • Source of ARD • Total Flow About 3 gpm • Very Poor Quality Water • Test Consisted of Adding Sugar/Alcohol To Well

Placed Into Dump Above Spring • Water Quality of ARD and Soil Gas Composition

Was Monitored • Question: Can Carbon Utilizing Bacteria Thrive in

Acidic Environment and Affect Water Quality?

Midas Spring pH vs. Flow

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

Sep

-00

Oct

-00

Nov

-00

Dec

-00

Jan-

01

Feb-

01

Mar

-01

Apr

-01

May

-01

Jun-

01

Jul-0

1

Aug

-01

Sep

-01

Oct

-01

Nov

-01

Dec

-01

Jan-

02

Feb-

02

Mar

-02

Apr

-02

Time

pH, F

low

in g

pm

Flow, gpm pH

Midas Spring - Water Quality

0

1

2

3

4

5

6

7

Time

Flow, gpm pH SO4, x10000 Al, x1000 Fe, x100

Soil Gas Monitoring Results

0 5

10 15 20 25 30 35 40 45

Date

Con

cent

ratio

n

Carbon Dioxide, % Oxygen, % H2S, ppm Temperature, C

Stepan Spring Anoxic Drain

• Low Flow ARD Contained Within Ferrocrete Canyon

• Canyon Filled with Manure/Limestone • Anoxic Drain Planted with Vegetation • Effective for pH control and Metal

Removal for Three years • Flow Diminishing • No signs of Failure

Stepan Spring Water Quality

0

2

4

6

8

10

12

14

Time

Flow, gpm pH Sulfate, x1000 Al, x1000 Fe, x100 Cu, x100

Tailing Dam Under Drain

Problem:

• Apparent Acid Generation In Tailings

• Water Draining From Tailings Becoming More Acidic

• Metals Becoming Soluble

Tailings Dam Underdrain pH

5.6

5.8

6

6.2

6.4

6.6

6.8

7

7.2

Time

pH

Water Quality Changes - Tailings Underdrain

0

50

100

150

200

250

300

350

400

Time

Con

cent

ratio

n, m

g/lit

er

Alkalinity Iron

Problem Solver – Water Trap

Water Trap

• Trap Prevents Oxygen Excursion Into Under-Drain System

• Acid Generation Was Caused By Air

• When Air Was Excluded, Acid Generation Ended and

The Water Quality Improved

Golden Sunlight Mine Bio-Treatment of Acid Producing...

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