Case Study - Landusky By Andy Robertson & Shannon Shaw.
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Transcript of Case Study - Landusky By Andy Robertson & Shannon Shaw.
Case Study - Landusky
By Andy Robertson & Shannon Shaw
The Landusky gold mine is located adjacent to the Zortman gold mine in the Little Rocky Mountains in Phillips County (~155 miles north of Billings)
Zortman Mine
Landusky Mine
The first mill was built in 1904 and underground mining continued off and on through to the 1970’s
A mining boom occurred in the district from 1923 - 1942. In 1942 production was shut down by the war production board
Open pit heap leach operations began in 1979 and continued until 1996 when the proponent went bankrupt.
Landusky Mine
Landusky Mine
Pit Complex
L87/91 Leach Pad
Lower Leach Pads
Waste Rock
L87/91 Leach Pad
Pit Complex
Waste Rock
L87/91 LP is one of the largest valley-filled leach pads holding ~120 million tonnes of spent ore
Reclamation Issues
• The property lies on the boundary of native tribal lands and on the groundwater divide
• Reclamation options evaluations were of 2 broad categories:– 1. Options including backfill of the pits– 2. Options that leave material where currently placed
• The most significant reclamation issue is that of water quality and water management.
• There are essentially 3 water types on the site:1. Clean water discharge2. ARD - treated with HDS lime treatment3. Spent ore leachate - currently land applied
Spent Ore Leachate
• Heap leach pads were operated at pH conditions of ~10.• A significant amount of sulfidic ROM ore was placed on the
leach pads - which is potentially acid generating• After operations, the leach pads were rinsed to drop the pH to
circum-neutral conditions and H2O2 was added to the leachate to break down CN
• The solutions were then land applied in a Land Application Disposal (or LAD) area - currently still in use
Spent Ore Leachate
• The LAD relies on the cation exchange in the soils and plant uptake of constituents.
• Solutions are irrigated over the surface to enhance evaporation and minimize surface water discharge.
Landusky Mine Annual Total Sulfate Loads by Facility
0 200,000 400,000 600,000 800,000 1,000,000 1,200,000 1,400,000 1,600,000 1,800,000
L-91
L-87
UPPER MONTANA GULCH
LOWER MONTANA GULCH
GOLD BUG DISCHARGE
SULLIVAN GULCH
L-83
MILL GULCH
L-85-86
L-84
L-79,80,81,82
SWIFT GULCH (mine area only)
KING CREEK (mine area only)
X-03
X-02
MT-09 + MT-11
X-01
lbs per year
Landusky Mine Annual Total Metals Loads by Facility
0 10,000 20,000 30,000 40,000 50,000 60,000
GOLD BUG DISCHARGE
SULLIVAN GULCH
UPPER MONTANA GULCH
L-83
L-84
MILL GULCHLOWER MONTANA GULCH
L-79,80,81,82
L-91
L-87
SWIFT GULCH (mine area only)X-03
L-85-86
KING CREEK (mine area only)
X-02
MT-09 + MT-11
X-01
lbs per year
Distribution of Landusky Mine Sub-Surface Sulfate Load
1%
66%
24%
9%IT to GW
IT to LAD
IT to WTP
IT to Sfc
Distribution of Landusky Mine Sub-Surface Metals Load
18%
80%
2% 0%IT to GW
IT to LAD
IT to WTP
IT to Sfc
The Field Survey Consisted of:• paste pH and paste TDS measurements• visual identification of:
– rock type– degree of oxidation– degree of alteration– surface precipitates
and staining– presence of visible
sulfides– any ‘unusual’ textures
Field Paste pH vs. Field Paste TDS
0
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0
Field Paste pH
Fie
ld P
ast
e T
DS
Dike samples
Leach Pad Samples
Pit Samples
Waste Rock Samples
In general, samples with low pH have high TDS values due to thepresence of soluble minerals on the grain surfaces. The exception is the leach pad samples for which the added alkalinity (during leaching) is maintaining near neutral pH values and contributing to TDS.
Surface ‘salts’
• Color on the leach pads was highly variable and in general not indicative of pH trends
Surface ‘salts’ - Mineralogical Analysis
• Powder XRD analyses confirm the presence of:– Calcite (CaCO3)
– Huntite (CaMg3(CO3)4)
– Jarosite (KFe3(SO4)2(OH)6
– Copiapite (Fe5(SO4)6(OH)2.20H2O– Akaganite (-FeOOH)
• Single crystal XRD analyses suggest:– Celadonite (K(Mg,Fe)(Fe,Al)[Si4O10](OH)2)
– Calcanthite (CuSO4.5H2O)
– Melanterite (FeSO4).7H2O
– Dumortierite (Al7(BO3)(SiO4)3O3)
mineralogical analysis being done by B. Sheriff and H. Jamieson at Queen’s University
Laboratory ARD Testing
• During the field reconnaissance survey, samples were collected for lab testing. Lab tests included:– Paste pH and conductivity on the ‘as received’ fines– modified acid base accounting (ABA) tests– inorganic carbon analyses– leach extraction analyses– forward acid titration tests– multi-element ICP analyses– net acid generation (NAG) tests, and– seive analyses
Modified Acid Base Accounting
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.20 2.40 2.60
Total Sulfur
Fie
ld P
ast
e p
H
Dike samples
Leach Pad Samples
Pit Samples
Tailings Samples
Waste Rock Samples
Modified Acid Base Accounting
0.0
5.0
10.0
15.0
20.0
25.0
30.0
0.0 5.0 10.0 15.0 20.0 25.0 30.0Neutralization Potential (NP) in kg CaCO3/tonne equivalent
Aci
d P
ote
ntia
l (A
P)
in k
g C
aC
O3
/tonn
e e
qui
vale
nt
Dike samples
Leach Pad Samples
Pit Samples
Tailings Samples
Waste Rock Samples
3:1
1:1
Forward Acid Titration Tests
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
0.00 5.00 10.00 15.00 20.00 25.00 30.00
Volume of H2SO4 added (mL)
Sa
mp
le p
H
Leach Pad Sample
Tailings Sample
Partially Oxidized Pit Sample
Oxidized Pit Sample
Unoxidized Pit Sample
Drilling Program
• A Becker hammer-type drill rig was used in order to minimize sample crushing and the geochemical disturbance of the samples
Borehole Instrumentation
Instrumented boreholes installed withslotted PVC, thermistors every 15 ft &pore gas sampling tubes every 15 ft To LAD
Drill Cuttings Sampling
Samples were collected every 10 ft & paste pH and EC measured,A sub-set of samples were submitted for laboratory testing
0.0
2.0
4.0
6.0
8.0
10.0
12.0
0.0 2.0 4.0 6.0 8.0 10.0 12.0
Laboratory Paste pH (on 'as received fines')
Fie
ld P
aste
pH
(on
'fin
es')
DHL80LP DHL83LP
DHL84LP DHL85LP
DHL87/91LP DHL87LP
DHL91LP DHZ84DK
DHZ85LP
Paste pH Results
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0
Acid Potential (kg CaCO3 equivalent)
Neu
tral
izat
ion
Pot
entia
l (kg
CaC
O3
equi
vale
nt)
DHL80LP DHL83LP
DHL84LP DHL85LP
DHL87LP DHL87/91LP
DHL91LP DHZ85LP
DHZ84DK
0.0
2.5
5.0
7.5
10.0
12.5
15.0
0.0 2.5 5.0 7.5 10.0 12.5 15.0
Modified ABA Results
pH
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
0.0 2.0 4.0 6.0 8.0 10.0 12.0D
ep
th (
5 f
oo
t in
terv
al
sta
rtin
g)
DHL87/91LP
CONDUCTIVITY ( S/cm)
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
0 1000 2000 3000 4000
De
pth
(5
fo
ot
inte
rva
l s
tart
ing
)
Geochemical Characteristics With Depth
0
10
20
30
40
50
60
70
0246810121416
L83 LP
Dep
th (
ft)
- 5
ft in
terv
al s
tart
ing
NP
AP
paste pH
0
10
20
30
40
50
60
70
80
90100
024681012
L84 LP
Dep
th (
ft)
- 5
ft in
terv
al s
tart
ing
NP
AP
paste pH
0
10
20
30
40
50
60
70
80
90100110120130140150160
024681012
L85/86 LP
Dep
th (
ft)
- 5
ft in
terv
al s
tart
ing
NPAPpaste pH
0
10
20
30
40
50
60
70
80
90100110120130140150
02468101214161820
L87 LP
Dep
th (
ft)
- 5
ft in
terv
al s
tart
ing
NPAPpaste pH
0
10
20
30
40
50
60
70
80
90100110120
051015202530354045
L87/91 LP
Dep
th (
ft)
- 5
ft in
terv
al s
tart
ing
NPAPpaste pH
0
10
20
30
40
50
60
70
80
90100110120130140150
0246810121416
L91 LP
Dep
th (
ft)
- 5
ft in
terv
al s
tart
ing
NPAPpaste pH
0
10
20
30
40
50
60
70
80
90100110
024681012
Z85/86 LP
Dep
th (
ft)
- 5
ft in
terv
al s
tart
ing
NPAPpaste pH
0
10
20
30
40
50
60
70
80
90100
02468101214
Z84 DK
Dep
th (
ft)
- 5
ft in
terv
al s
tart
ing
NPAPpaste pH
0
10
20
30
40
50
60
70
80
90
100
110
120
0 200 400 600 800 1000 1200
Dep
th (
ft)
- 5
ft in
terv
al s
tart
ing
Soluble Amount (mg/kg)
0
10
20
30
40
50
60
70
80
90
100
110
120
0 50 100 150
0
10
20
30
40
50
60
70
80
90
100
110
120
0 5 10 15 20 25 30 35 40 45
kg CaCO3/t equiv
Dep
th (
ft)
- 5
ft in
terv
al s
tart
ing
0
10
20
30
40
50
60
70
02468101214160
10
20
30
40
50
60
70
80
90100
024681012
0
10
20
30
40
50
60
70
80
90100110120130140150160
0246810120
10
20
30
40
50
60
70
80
90100110120130140150
02468101214161820
0
10
20
30
40
50
60
70
80
90100110120
0510152025303540450
10
20
30
40
50
60
70
80
90100110120130140150
0246810121416
0
10
20
30
40
50
60
70
80
90100110
024681012
0
10
20
30
40
50
60
70
80
90100
024681012140
10
20
30
40
50
60
70
80
90
100
110
120
0 5 10 15 20 25 30 35 40 45
NP
AP
paste pH
0
10
20
30
40
50
60
70
02468101214160
10
20
30
40
50
60
70
80
90100
024681012
0
10
20
30
40
50
60
70
80
90100110120130140150160
0246810120
10
20
30
40
50
60
70
80
90100110120130140150
024681012141618200
10
20
30
40
50
60
70
80
90100110120
0510152025303540450
10
20
30
40
50
60
70
80
90100110120130140150
0246810121416
0
10
20
30
40
50
60
70
80
90100110
024681012
0
10
20
30
40
50
60
70
80
90100
024681012140
10
20
30
40
50
60
70
80
90
100
110
120
0 200 400 600 800 1000 1200
ALKALINITYACIDITYSULPHATECa
0
10
20
30
40
50
60
70
80
90
100
110
120
0 50 100 150
Dep
th (
ft)
- 5
ft in
terv
al s
tart
ing
Soluble Amount (mg/kg)
0
10
20
30
40
50
60
70
80
90
100
110
120
0.00 0.05 0.10 0.15 0.20
Dep
th (
ft)
- 5
ft in
terv
al s
tart
ing
Soluble Amount (mg/kg)0
10
20
30
40
50
60
70
80
90
100
110
120
0.00 0.05 0.10 0.15 0.20
Cu
Zn
Co
0
10
20
30
40
50
60
70
80
90
100
110
120
0 50 100 150
Fe
Mg
Na
Oxygen (%)
0
20
40
60
80
100
120
19 19.5 20 20.5 21
Dep
th fr
om s
urfa
ce (
ft)
04/13/00
05/08/00
07/17/00
CO2 (%)
0
20
40
60
80
100
120
0 0.2 0.4 0.6 0.8 1
Dep
th f
rom
sur
face
(ft
)
04/13/00
05/08/00
07/17/00
O2, & CO2 Characteristics With Depth (Lower elevation hole)
O2 (%)
0
20
40
60
80
100
120
140
160
18.0 19.0 20.0 21.0 22.0
Dep
th fr
om s
urfa
ce (
ft)
04/13/00
05/08/00
07/17/00
CO2 (%)
0
20
40
60
80
100
120
140
160
0.0 0.2 0.4 0.6 0.8 1.0
Dep
th f
rom
sur
face
(ft
)
04/13/00
05/08/00
07/17/00
O2, & CO2 Characteristics With Depth (higher elevation hole)
Temperature (Celsius)
0
20
40
60
80
100
120
0 2 4 6 8 10 12
Dep
th f
rom
sur
face
(ft
)
04/13/00
05/08/00
07/17/00
Temperature Characteristics With Depth
Temperature (Celsius)
0
20
40
60
80
100
120
140
160
0.0 5.0 10.0 15.0 20.0
Dep
th f
rom
sur
face
(ft
)
04/13/00
05/08/00
07/17/00
Lower elevation hole Higher elevation hole
