XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1737
Effect of Contact Time on the Extraction Efficiency of
Ta and Nb
The effect of contact time on the extraction efficiency of Ta
and Nb was studied at room temperature using Aliquat ®
336 concentration of 14%, an O/A ratio of 2, with pH of
the aqueous phase being maintained at 1.1. The results are
presented in Figure 6.
The results shown in Figure 6 indicate that complete
coextraction of Ta and Nb could be achieved within 4 min-
utes of contact time. Exceeding the time over this period
did not improve Ta and Nb extraction degree. The distri-
bution coefficients for Nb and Ta decrease from 81 and
494 respectively to 39 and 329 when contact time increases
from 4 to 15 minutes. A contact time of 4 minutes has
been accordingly selected as an optimal one and used in
further tests.
Effect of Aqueous Phase pH
The pH of the aqueous phase is an important parameter to
evaluate during solvent extraction of Ta and Nb. It gener-
ally allows the chemical properties of Ta and Nb complexes
to be modified, so that they could be separated with high
selectivity factors. In the current work, sulfuric acid and
NaOH (5M) solutions were used to adjust pH. Depending
on the volume used to achieve a given pH value, Ta and
Nb grades inside the aqueous phase were recalculated. The
effect of the aqueous phase pH was studied at room tem-
perature using an Aliquat ® 336 concentration of 14%, O/A
ratio of 2 and contact time of 4 minutes. These results are
illustrated in Figure 7.
Figure 7 suggests that selective extraction of Ta and
Nb is not possible through varying the pH of the aqueous
phase. When pH is increased from 1.1 to 1.2, the
3 5 8 10 12 14
1
10
100
1000
10000
100000
[Aliquat] %
Ca
Fe
Mn
(a)
3 5 8 10 12 14
1
10
100
1000
10000
100000
Ca
Fe
Mn
[Aliquat] %
(b)
Figure 5. Separation factors of Nb (a) and Ta (b) with respect to Ca, Fe and Mn
0 2 4 6 8 10 12 14 16
50
60
70
80
90
100
E
Nb
E
Ta
D
Nb
D
Ta
Contact time (minutes)
0
100
200bu
300o
400tn
500
Figure. 6. Effect of contact time on the extraction efficiency
of Ta and Nb by Aliquat® 336
0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
80
85
90
95
100
E
Nb
E
Ta
D
Nb D
Ta
pH of the aqueous phase
0
100
200bu
300c
400
500
600
Figure 7. Effect from aqueous phase pH on the extraction of
Ta and Nb
SFNb/M SFTa/M
Extracti
,
%
Distri
ti
cefficie
(
Extracti
,
%
Distri
ti
efficient
(D)
Effect of Contact Time on the Extraction Efficiency of
Ta and Nb
The effect of contact time on the extraction efficiency of Ta
and Nb was studied at room temperature using Aliquat ®
336 concentration of 14%, an O/A ratio of 2, with pH of
the aqueous phase being maintained at 1.1. The results are
presented in Figure 6.
The results shown in Figure 6 indicate that complete
coextraction of Ta and Nb could be achieved within 4 min-
utes of contact time. Exceeding the time over this period
did not improve Ta and Nb extraction degree. The distri-
bution coefficients for Nb and Ta decrease from 81 and
494 respectively to 39 and 329 when contact time increases
from 4 to 15 minutes. A contact time of 4 minutes has
been accordingly selected as an optimal one and used in
further tests.
Effect of Aqueous Phase pH
The pH of the aqueous phase is an important parameter to
evaluate during solvent extraction of Ta and Nb. It gener-
ally allows the chemical properties of Ta and Nb complexes
to be modified, so that they could be separated with high
selectivity factors. In the current work, sulfuric acid and
NaOH (5M) solutions were used to adjust pH. Depending
on the volume used to achieve a given pH value, Ta and
Nb grades inside the aqueous phase were recalculated. The
effect of the aqueous phase pH was studied at room tem-
perature using an Aliquat ® 336 concentration of 14%, O/A
ratio of 2 and contact time of 4 minutes. These results are
illustrated in Figure 7.
Figure 7 suggests that selective extraction of Ta and
Nb is not possible through varying the pH of the aqueous
phase. When pH is increased from 1.1 to 1.2, the
3 5 8 10 12 14
1
10
100
1000
10000
100000
[Aliquat] %
Ca
Fe
Mn
(a)
3 5 8 10 12 14
1
10
100
1000
10000
100000
Ca
Fe
Mn
[Aliquat] %
(b)
Figure 5. Separation factors of Nb (a) and Ta (b) with respect to Ca, Fe and Mn
0 2 4 6 8 10 12 14 16
50
60
70
80
90
100
E
Nb
E
Ta
D
Nb
D
Ta
Contact time (minutes)
0
100
200bu
300o
400tn
500
Figure. 6. Effect of contact time on the extraction efficiency
of Ta and Nb by Aliquat® 336
0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
80
85
90
95
100
E
Nb
E
Ta
D
Nb D
Ta
pH of the aqueous phase
0
100
200bu
300c
400
500
600
Figure 7. Effect from aqueous phase pH on the extraction of
Ta and Nb
SFNb/M SFTa/M
Extracti
,
%
Distri
ti
cefficie
(
Extracti
,
%
Distri
ti
efficient
(D)