Transcript Jeffrey

Elution behaviour of metals from carbon
SAIMM 2009
M Jeffrey
R Pleysier
K Bunney
Background
• National Pollution Inventory reporting (NPI)
• 93 reportable substances
• Objectives
• Help industry and government with environmental planning and
management
• Provide communities with information on emissions
• Promote waste minimisation, cleaner production and efficiency
• Gold mines
• Identified as major emitter of Hg
• Not amalgamations but as ppm levels in cyanide leach liquors.
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CSIRO. Elution behaviour of metals from carbon
Project Objectives - general
• ID toxic trace elements in CIP streams
• Deportment
• Understand of the dissolution of toxic trace elements. (cyanide)
• Potential to avoid or sequester in benign form.
• Adsorption/elution characteristic
• Hg, Ni, Cu, Sr, Cd, As, Pb, Si, Se, Sb, Te, Cr, ……..(19)
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CSIRO. Elution behaviour of metals from carbon
Project Objectives - specific
• Hg speciation ( carbon)
• Mine site - Hg only partly elutes
•  EW and smelt
•  regen gases
• Manage Hg in one concentrated stream
• Elution Column – construct , description
(better stripping of Hg)
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CSIRO. Elution behaviour of metals from carbon
Laboratory Elution Column
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CSIRO. Elution behaviour of metals from carbon
Laboratory Elution Column
Pump
• Altex model 110A (PD piston type)
• 0.1 – 10 mL/min
• 0 – 25,000 kPa (4000 psi)
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CSIRO. Elution behaviour of metals from carbon
Laboratory Elution Column
Pump
Gauges (2)
• 0 – 1500 kPa (0-230 psi)
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CSIRO. Elution behaviour of metals from carbon
Laboratory Elution Column
Pump
Gauges
PRV (2)
• 70 – 1500 kPa adjustable
(10 – 225 psi)
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CSIRO. Elution behaviour of metals from carbon
Laboratory Elution Column
Pump
Gauges
PRV
Column
• ØID 25 x 600 mm SS swagelok fittings
• 100 g carbon capacity
• 150 mL void volume.
• Screens top and bottom (300μm)
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CSIRO. Elution behaviour of metals from carbon
Laboratory Elution Column
Pump
Gauges
PRV
Column
Heating
• Electrical heating tape/insulated
• T/C (type k)
• PID controller (Eurotherm CE 375)
• Pre heater coil for eluant.
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CSIRO. Elution behaviour of metals from carbon
Laboratory Elution Column
Pump
Gauges
PRV
Column
Heating
Cooling
• SS coil in water bucket
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CSIRO. Elution behaviour of metals from carbon
Laboratory Elution Column
Pump
Gauges
PRV
Column
Heating
Outlet
•3 way
- to gauge
- prv
- needle control valve
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CSIRO. Elution behaviour of metals from carbon
Commissioning
• Samples
•
•
•
•
Local mine site
C1
C1 aw
C2 aw
(Au 909 g/t
Hg 187 g/t)
(Au 1140 g/t
Hg 229 g/t)
(Au 355 g/t
Hg 92 g/t )
• Commissioning
• AARL
•
•
•
•
•
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(2% NaCN + 2% NaOH)
130OC
Pressure 200 kpa
30 min bake
20 BV DI
CSIRO. Elution behaviour of metals from carbon
Commissioning -profiles
Gold Elution
100
100%
90
90%
80
80%
[Au] (mg/L)
700 kPa
60
60%
50%
40
40%
30
30%
20
20%
10
10%
0
14
70%
50
0
500
1000
1500
Eluant mass (g)
CSIRO. Elution behaviour of metals from carbon
2000
•200 kpa gave
poor flow control
0%
2500
Au Recovery
200 kPa
70
Pressure
•700 kpa gave
better flow and
temp control
•Profile similar-not
effected by
pressure
Commissioning -profiles
Mercury elution
40
100%
90%
35
•Profiles similar
80%
70%
25
60%
20
50%
40%
15
30%
200 kPa
10
700 kPa
5
200 kPa
0
0
500
1000
1500
Eluant mass (g)
CSIRO. Elution behaviour of metals from carbon
700 kPa
2000
20%
10%
0%
2500
•Hg eluted sl faster
Recovery
Concentration (mg/L)
30
15
Pressure
•Recovery sl lower
•Earlier than gold
•Typical plant
recovery 50-60%
Plant sample –Au profiles
Gold Elution
250
100%
•3 loaded carbon
samples from local
minesite
90%
80%
70%
150
60%
C1 loaded
C1 AW
100
C2 AW
50
50%
40%
10%
0
16
500
1000
1500
Eluant mass (g)
CSIRO. Elution behaviour of metals from carbon
2000
•Good profiles and
good recoveries
for gold
30%
20%
0
Recovery
Concentration (mg/L)
200
Samples
0%
2500
•Results similar to
plant data.
Plant sample – Hg profiles
100
100%
90
90%
80
80%
70
70%
60
60%
50
50%
40
40%
30
C1 loaded
30%
20
C1 AW
20%
10
C2 AW
10%
0
0
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500
1000
1500
Eluant mass (g)
CSIRO. Elution behaviour of metals from carbon
2000
0%
2500
Samples
•As previous
•Hg recovery only
57%
Recovery
Concentration (mg/L)
Mercury Elution
•Lower if not acid
washed 41%.
•Mechanism of
improvement yet to
be determined.
Vary temp – Au profiles
Gold elution
350
100%
Effect of temp
90%
•130oC = 93% Au
80%
•160oC = 97% Au
70%
•Higher temp
250
60%
200
50%
150
40%
100
130ºC
160ºC
50
30%
20%
10%
0
0
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500
1000
1500
Eluant mass (g)
CSIRO. Elution behaviour of metals from carbon
2000
0%
2500
Recovery
Concentration (mg/L)
300
•Faster elution
•Higher [Au]s
•Higher recovery.
Vary temp – Hg profiles
100
100%
Effect of temp
90
90%
•130oC = 57% Hg
80
80%
•160oC = 40% Hg
70
70%
60
60%
50
50%
40
40%
30
30%
20
130ºC
20%
10
160ºC
10%
0
0
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500
1000
1500
Eluant mass (g)
CSIRO. Elution behaviour of metals from carbon
2000
0%
2500
•Higher temp =
Recovery
Concentration (mg/L)
Mercury elution
•LESS mercury.
•Higher temp
decomposes
NaCN ?
Vary cyanide – Au profiles
Gold elution
300
Effect of cyanide
90%
•Increasing [NaCN]
80%
200
60%
150
50%
0%
100
2%
5%
50
40%
30%
20%
10%
0
0
20
•Increases rate Au
70%
200
400
600
800
1000 1200
Eluant mass (g)
CSIRO. Elution behaviour of metals from carbon
1400
1600
0%
1800
Recovery
Concentration (mg/L)
250
100%
•Increases recovery
Vary cyanide – Hg profiles
Mercury elution
140
100%
Effect of cyanide
90%
•Increasing [NaCN]
120
100
80
70%
•Increases rate Hg
60%
•Increases recovery
50%
60
40%
0%
2%
20%
5%
10%
0
0
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200
400
600
800
1000 1200
Eluant mass (g)
CSIRO. Elution behaviour of metals from carbon
1400
•But still only 61%
30%
40
20
Recovery
Concentration (mg/L)
80%
1600
0%
1800
•Potential to leave
Hg on carbon
Zadra – Au profiles
Gold elution
250
100%
90%
•Maintains [CN]
80%
•Slower rate Au
70%
150
60%
Recovery
Concentration (mg/L)
200
50%
100
AARL
*
Zadra
50
40%
30%
20%
10%
0
0
500
1000
1500
Eluant mass (g)
* soak period added to determine impact on Hg elution
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CSIRO. Elution behaviour of metals from carbon
2000
Zadra
0%
2500
Zadra – Hg profiles
100
100%
Zadra
90
90%
•Maintains [CN]
80
80%
•Similar rate Hg
70
70%
60
60%
•Improved recovery
50
50%
•76% Hg recovery
40
40%
Recovery
Concentration (mg/L)
Mercury elution
30
AARL
20
Zadra
10
20%
10%
0
0
23
30%
500
1000
1500
Eluant mass (g)
CSIRO. Elution behaviour of metals from carbon
2000
0%
2500
Zadra – Au at 110oC
Gold elution
250
Zadra
90%
•Maintains [CN]
80%
•Much slower rate
70%
150
AARL 130ºC
60%
Zadra 110ºC
50%
100
Recovery
Concentration (mg/L)
200
100%
40%
30%
50
20%
10%
0
0
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500
1000
1500
Eluant mass (g)
CSIRO. Elution behaviour of metals from carbon
2000
0%
2500
•Very poor recovery
•Temp important for
Au
Zadra – Hg at 110oC
100%
90
90%
•Maintains [CN]
80
80%
•Rapid elution
70
70%
60
60%
50
50%
40
40%
30
AARL 130ºC
20
Zadra 110ºC
10
30%
20%
10%
0
0
25
Zadra
100
Recovery
Concentration (mg/L)
Mercury elution
500
1000
1500
Eluant mass (g)
CSIRO. Elution behaviour of metals from carbon
2000
0%
2500
•Recovery 87%
Data Split elution
Gold
Mercury
•high temp
low temp
•low [CN]
high [CN]
Mutually exclusive conditions  split elution?
•Zadra at 90oC + 130oC AARL
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CSIRO. Elution behaviour of metals from carbon
Split
Split elution
250
100%
Conditions
•Zadra at 90oC
200
80%
Au
150
Recovery
Concentration (mg/L)
Hg
60%
100
Series
2
•2% NaOH
•2% NaCN
•1500 mL
40%
50
20%
•AARL at 130oC
•30 min soak
0
0
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500
1000
1500
2000
Eluant mass (g)
CSIRO. Elution behaviour of metals from carbon
2500
0%
3000
•DI elution 1000 mL
Split elution results
Mercury
•98% recovery in 10BV at 90oC
•Eluate… high Hg, low Au
•Hg recovery via S ppt etc
Gold
•10-15% Au into Hg eluate
•Further refinements possible (lower temp further???)
•Gold recycle recovery?
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CSIRO. Elution behaviour of metals from carbon
Summary
• Recovery of Hg into one stream possible.
(ie removal from carbon/regen circuit desirable  solution)
• Elute/separate Hg/Au with one set of elution conditions not
possible,
• But split or sequential elutions works well
• Further optimisation/recovery possible
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CSIRO. Elution behaviour of metals from carbon
Further work / objectives
• ID other toxic trace elements in CIP streams
• Hg started, As, Se, Cd, Sb, Te, Pb, Cr, Ni, organics ???
• Deportment
• What accumulate where?
• Potential to avoid or sequester in benign form.
• Adsorption/elution characteristic
• Effect of acid washing?
• Impact on silver
• In progress.
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CSIRO. Elution behaviour of metals from carbon
Minerals
Ron Pleysier
Project Scientist
Phone: 08 9334 8923
Email: [email protected]
Web: www.csiro.au/group
Thank you
Contact Us
Phone: 1300 363 400 or +61 3 9545 2176
Email: [email protected] Web: www.csiro.au
Split elution - Ag
5% NaCN at 90ºC + DI at 130ºC
Hg
Silver
Au
250
Conc (mg/L)
Ag
200
•Elutes with Hg at
low temp in CN
150
•Residual with gold
100
50
0
0
500
1000
1500
Eluant mass (g)
CSIRO. Elution behaviour of metals from carbon
2000
2500
3000
Split elution – reverse method
DI at 140ºC + 5% NaCN at 110ºC
Hg
250
Silver
Au
Ag
•Partially elutes with
Au at high temp low
CN
150
•But needs CN to
elute bulk
100
50
0
0
500
1000
1500
2000
2500
3000
Eluant mass (g)
Silver elution
250.00
100
90
80
70
150.00
60
50
100.00
40
30
50.00
20
10
0.00
0
500
1000
1500
Eluant volume (mL)
CSIRO. Elution behaviour of metals from carbon
2000
0
2500
Ag recovery %
200.00
[Ag] mg/L
Conc (mg/L)
200
•Best conditions for silver elution
130oC with 2%NaCN and NaOH
Hg Elutions - updates
• 10M HNO3 will strip Hg from carbon on the bench overnight.
• NaCN strips (atmospheric) at 40, 60, 75, 90oC
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CSIRO. Elution behaviour of metals from carbon