flotation of ultramafic ni ore - mcgill university
TRANSCRIPT
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Flotation of Ultramafic Ni Ore
Salah Uddin
Research SeminarMarch 12, 2010
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Froth: Sulphides and Ultramafic
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Convention flotation
0
2
4
6
0 20 40 60 80 100Ni recovery (%)
Ni g
rade
(%)
20
25
30
35
0 20 40 60 80 100Ni recovery (%)
MgO
gra
de (%
)H1 H2L H2UH3L H3U H4
Dai et al., 2009
Low Ni grade achieved through conventional flotation Not sufficient rejection of MgO minerals
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Possiblity-1: Metal ion activation
With Cu
With Ni
D. Fornasiero and J. Ralston, 2005
Activation of negatively charged silicates by adsorbed positively charged metal ions possibly promotes MgO recovery
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Effect of metal ions on surface charge
5
-0.0015
-0.001
-0.0005
0
0.0005
7.5 8.5 9.5 10.5 11.5
SP (V
)
pH
ore
0.006M MgCl2
0.018M MgCl2
Observation – Mg2+ interacts
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Observation – Shift of potential to a more negative one suggests removal of positive metallic species from surfaces. This also indicates presence of
ionic species in the system
Effect of EDTA
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pH 9 pH 11 pH 11 with EDTA
EDTA: Visual observations
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Flotation test-1
CMC0.05g
1 wt% EDTA
Ore100g
Adjust pH~10Na2CO3
PAX0.004g
MIBC0.003g
Concentrates 1,2 and 3
Na2CO31g
Identify the effect of metal ions
Tail
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Ni grade vs recovery
0
2
4
6
0 10 20 30 40 50 60 70 80
Ni recovery (%)
Ni g
rade
(%)
0 wt% EDTA
1 wt% EDTA
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Mg grade vs. recovery
Overall, change in grade/recovery relationships suggests metal ion activation has some influence on flotation
0
5
10
15
20
25
0 5 10 15 20 25 30 35 40 45 50
Mg recovery (%)
Mg
grad
e (%
)
0 wt% EDTA
1 wt% EDTA
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Possibility-2: Entanglement
Micrograph of a ore sample shows Fibres apparently entangle the other particles
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Score Compound Name
Chemical Formula
42 Clinochrysotile
Mg3 Si2 O5 ( O H )4
34 Lizardite 1\ITT\RG
Mg3 Si2 O5 ( O H )4
33 Magnesium Aluminum Silicate
Mg O ! Al2 O3 ! Si O2
MgO bearing minerals
A considerable portion of the ore is occupied by Clinochrysotile. This a type of chrysotile, the most prevalent form of naturally occurring asbestos
This can influence flotation by 1) entangle and entrainment and 2) Impeding bubble motion (higher viscosity pulp)
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Fibre disintegration
Chrysotile
Amphibole
23 2 5 4 4 2( ) 6 3 2 ( )Mg Si O OH H Mg Si OH H O+ ++ → + +
Serpentine-acid reaction
One way to tackle this problem would be by weakening and disintegrating chrysotile fibres using acid
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Flotation test-2
CMC
1 wt% EDTA
Ore100g (pH ~ 7)
Adjust pH 10Na2CO3
PAX MIBC
Concentrates 1,2 and 3
Tail
HCl
Identify the effect of fibre disintegration
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0% HCl 5% HCl
10% HCl 15% HCl
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Dissolved metal ions
Amount of dissolved Fe, Ni and Mg in solution was determined (ICP-MS)Higher dissolution of Mg corresponds to higher dimensional instability
and disintegration of fibres
0
2
4
6
8
10
12
0 5 10 15
Dis
tribu
tion
(%)
HCl
FeNiMg
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Ni grade vs recovery
Significant increase in Ni grade vs recovery was achieved with 10 and 15 wt% HCl
0
4
8
12
0 10 20 30 40 50 60 70 80 90 100
Ni recovery (%)
0 wt% HCl
5 wt% HCl
10 wt% HCl
15 wt% HCl
Ni g
rade
(%)
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Mg grade vs recovery
Significant decrease in Mg in the concentrates with 10 and 15 wt% HCl
10
14
18
22
0 5 10 15 20 25
Mg recovery (%)
Mg
grad
e (%
)
5 wt% HCl
10 wt% HCl15 wt% HCl
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Insol recovery
Amount of insol in concentrates decreased with HCl concentration
0
10
20
30
40
con 1 tail
% In
sol
0% HCl
5% HCl
10% HCl
15% HCl
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Conclusions
• Physical entanglement of chrysotile fibres with the particles most probably plays the key role
• Fibres can be effectively disintegrated using combined chemical (acid) and mechanical (grinding) treatment
• Result is significant improvement in Ni metallurgy