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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
SRB-Driven Sulfide Precipitation Demonstration Project
Midas AMD
Settling Pond
SRB Bioreactor
Treated Effluent
Recycle
Nutrients
Sludge Removal
SRB-Driven Sulfide Precipitation Demonstration Project
SRB-Driven Sulfide Precipitation Demonstration Project
0 1 2 3 4 5 6 7
Jul-01 Nov-01 Feb-02 May-02 Sep-02 Date
pH
In Mid Eff
SRB-Driven Sulfide Precipitation Demonstration Project
0.01
0.1
1
10
100
1000
10000
Jul-01 Nov-01 Feb-02 May-02 Sep-02 Date
Dis
solv
ed A
lum
inum
(mg/
L)
. In Mid Eff
SRB-Driven Sulfide Precipitation Demonstration Project
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
SRB-Driven Sulfide Precipitation Demonstration Project
0.1
1
10
100
1000
Jul-01 Nov-01 Feb-02 May-02 Sep-02 Date
Dis
solv
ed Ir
on (m
g/L)
. In Mid Eff
SRB-Driven Sulfide Precipitation Demonstration Project
0.001
0.01
0.1
1
10
100
Jul-01 Nov-01 Feb-02 May-02 Sep-02 Date
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 Demonstration Project
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