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Depression of pyrite in porphyry
co er flotation
Ian Wark Research InstituteAustralian Research Council Special Research Centre
For Particle and Material Interfaces
M. Zanin and S. Farrokhpay
Case Study
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High pyrite recovery in Cu/Mo operation
4800 tphd80 = 150 m
FINAL TAIL
SCAVENGER
FINAL CON
CLEANERCOLUMNS
ROUGHERFEED
2.0 % Cp
1.6 % PyBall Mills
SIPX
grade recovery
Cp % Py % Cp % Py %
65-70 10-15 88-90 20-30
Re-grindVertical Mills
CLNR SCAV1CLNR SCAV2
Thio Lime
Case Study
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Plant Evidence
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Rougher Con, pH = 10.5, Eh= 250 mV SHE
Pyrite reports to the Cu concentrate even at
high pH
00
2020
4040
6060
8080
100100
1212101088664422
Flotationrecovery(%)
PyPy
Cp
Case Study
Pyrite should not float at high pH (Gaudin,1957):
Maximum pyrite recovery in the
intermediate size ranges
true flotation
pp
Xanthate adsorp. density [ ]
OH
Xlog
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Possible mechanisms for pyrite recovery
Cu 2+
H O2OH
-CpCp
1. Insufficient liberation from
the copper sulphide
2. Surface Cu activation
and genuine flotation
O2
grinding
medium
pyrite
Cu-sulphide
e-
e-Fe 3+
OH-
Galvanic interactions in complex sulphideores (Huang & Grano, 2005)
yy
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50
60
70
80
90
s[%]
Pyrite Liberation Data - Survey 5
Pyrite in the Rougher Con is Liberated
Pyrite is not recovered
due to mineralogical
association with
90-100%30-90%
0-30%
Ro Feed
Ro Conc
Cell 9 & 10 Conc
Ro/Scav Tail
0
10
20
30
40Ma
Liberation
QEM-Scan analysis Case Study
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Time-of-Flight Secondary Ion Mass
Spectrometry: ToF-SIMS
+++
No.
ofCou
nts
Ga+ 11 kHzMass resolution ~9000
in Bunched Mode
7
m / z
Pulsed
electronflood
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0.5
0.6
Pyrite +SIMSAverage with 95% confidence, N=30
Sample 1 - Rghr Con
Sample 2 - Cell 10 Con0.5
0.6
s
Pyrite -SIMSAverage with 95% confidence, N=30
Sample 1 - Rghr Con
Sample 2 - Cell 10 Con
Pyrite in the concentrate is Cu activated
Copper and collector detected on the surface of pyrite
More Si, Al, K, Ca and O on the slow-floating pyrite Case Study
Copper (+)
Fe-S
0.0
0.1
0.2
0.3
0.4
Normalisedcoun
ts
Species
0.0
0.1
0.2
0.3
0.4
Normalisedcount
Species
IBX (PA-)
Fe-S
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Laboratory Work
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ROCSS- + SO32- + HSO3
- + O2
ROH + 2S2O32- + CO2
X
SO32-
Py[5S0] + 5SO32- Py[S2O3
2-] + 4S2O32-
S0
Na2SO3 and DETA to depress pyrite
Reduced surface hydrophobicity
Decomposition ofxanthate
Pyrite
Cu
DETAO2
Cu (OH)2
2
CH2Cu
CH2
H2N NH
CH2 CH2}
Complexation
with Cu
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FEEDO2/
Condit.SIPX DETA, Na2SO3 frother flotation
Tail
Conditioning: O2/air/no gas to control Eh and
DO level in the pulp
Flotation Baseline
Rghr Con (Plant)
Ore 1
Con 1, 2, 3, 4
0-30 mins 2 mins 2 mins 1 min
Rghr Feed (Lab grind)
+Thio primary coll.
Ore 2
Cu % Fe % Cp % Py %
Ore 1 0.66 3.4 2.0 1.6
Ore 2 0.44 4.6 1.2 9.7Feed H/G
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Depression of pyrite in the rougher
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60
80
100
ery[%]
60
80
100
ery[%]
Limited depression of pyrite with lime
Flotation tests on plant rougher con (60% Cp, 18% Py) (Ore 1)Pyrite is Cu and
xanthate activated
0
20
40
0 4 8 12 16 20
PyriteReco
time [min]
pH 12 with Lime
baseline (pH 10)
0
20
40
0 20 40 60 80 100
PyriteReco
Chalcopyrite Recovery [%]
pH 12 with Lime
baseline (pH 10)
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60
80
100
[%]
BaselineO2
O2+DETA
O2 +Na2SO3
60
80
100
[%]
Depression of pyrite with Na2SO3 and DETA
After intense
oxygenationFlotation tests on plant rougher con (60% Cp, 18% Py) (Ore 1)
pH = 10.5 pH = 10.5
0
20
40
0 20 40 60 80 100
PyriteRecover
Chalcopyrite Recovery [%]
0
20
40
0 4 8 12 16 20
PyriteRecover
time [min]
Baseline
O2
O2+DETA
O2 +Na2SO3
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Depression of pyrite in the rougher feed
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80
100
[%]
Baseline
Xanth+Na2SO3+Xanth
Xanth+Na2SO3
80
100
[%]
Baseline
Xanth+Na2SO3+Xanth
Xanth+Na2SO3
No xanthate
Chalcopyrite is
not affected
Na2SO3 reduces the adsorption of xanthate
on pyrite in the feedFloat tests on rghr feed ground in the lab (1.2% Cp, 10% Py)(Ore 2)
pH = 10.5 pH = 10.5
0
20
40
0 3 6 9 12 15
PyriteRecovery
time [min]
No xanthate
0
20
40
0 20 40 60 80 100
PyriteRecovery
Chalcopyrite Recovery [%]Pyrite re-activates if
further SIPX is added
after Na2SO3
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Conclusions (Case Study)
Pyrite in the feed was Cu activated, and adsorbed xanthate
even at high pH (>10.5), becoming highly floatable
Limited pyrite depression was achieved by increasing the pHwith lime
2 3
activation of pyrite in the presence of O2, reducing pyrite
recovery by 50%.
However, further addition of xanthate after depression withNa2SO3 re-activated pyrite
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Conclusions (Generic)
Xanthate collectors appear not to be very selective versuspyrite
The use of sodium sulphite (Na2SO3) and similar sulphoxyspecies (Na2S2O5, Na2S2O3) or sulphur dioxide gas (SO2) may
significantly reduce/reverse xanthate adsorption on pyrite
Pyrite may re-activate down the bank if furhter xanthate isadded
For ores containing highly floatable pyrite, the use of moreselective collectors (e.g. thionocarbamates) may be preferable
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Acknowledgements
The authors acknowledge the financial support of:
Australian Research Council (ARC)
Sponsors of the AMIRA International P260E project
Thank you!