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Flotation of Ultramafic Ni Ore
Salah Uddin
Research SeminarMarch 12, 2010
Froth: Sulphides and Ultramafic
3
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
4
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
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
6
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
7
pH 9 pH 11 pH 11 with EDTA
EDTA: Visual observations
8
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
9
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
10
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
11
Possibility-2: Entanglement
Micrograph of a ore sample shows Fibres apparently entangle the other particles
12
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)
13
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
14
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
0% HCl 5% HCl
10% HCl 15% HCl
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
17
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
(%)
18
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
19
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
20
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
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