1736 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
by Aliquat ®336. This method consists in plotting log
D(Ta,Nb) =f(log [Aliquat ® 336, M]). The slope of the result-
ing straight line should be close to 3, considering that Ta
and Nb oxalate complexes are in the forms )TaO(C O
2 4 3
3 -
and )NbO(C O
2 4 3
3 -respectively (Jehng and Wachs, 1991).
Figure 3 illustrates the relationship between the logarithm
of D(Ta,Nb) and that of Aliquat ®336 concentration.
Figure 3 indicates that the trend lines for both met-
als have slopes closer to 2 rather than to 3. This suggests
that not all of the Ta and Nb oxalate complexes involved
in the extraction mechanism with Aliquat ® 336 are met
in the form of )TaO(C O
2 4 3
3 -and )NbO(C O
2 4 3
3 -
.Literature data (Deblonde et al., 2019b Jehng and
Wachs, 1991), affirm that Ta and Nb can form differ-
ent complexes in oxalic media. Depending on the aque-
ous phase pH, Nb can present different oxalate complexes
such as: )(NbO(C O H O)
2 4 2 2 2
-,)NbO(C O
2 4 3
3 -,
)()NbO(C O OH
2 4 2 2 2
3- ,)NbO(C O OH O)
2 4 2 2 2
-^h(H ,
()(Nb O C O H O)
2 4 2 4 2 2 2
2- .A similar chemistry is also valid
for Ta, given its similarities with Nb. Based on these obser-
vations, we are inclined to assume that it is the bivalent
complex that is extracted by Aliquat ® 336.
FT-IR spectroscopy was used to identify the interac-
tion pattern between Aliquat ® 336 and Ta and Nb oxa-
late complexes within the 4000–400 cm–1 spectra region.
The IR spectra of the organic phases of Aliquat ® 336 and
the organic phase loaded with Aliquat ® 336-Nb (Ta) are
depicted in Figure 4.
The presence of Aliquat ® 336 functional groups in both
IR spectra witnessed in Figure 4, confirms that the loaded
organic phase comprises both oxalates-Nb(Ta) complex and
Aliquat ® 336. Both spectra show characteristic quaternary
amine peaks at 1462 and 1383 cm–1. These peaks occur at
1378 cm–1 and in the region from 1460 to 1467 cm–1 have
been attributed to the vibrations of the N+–CH
3 bonds of
the quaternary amine (Emam and El-Hefny, 2023 Kunene
et al., 2020 Lee et al., 2020). Peaks 2967cm–1 and 2860
cm–1 are attributed to C–H bond vibrations. Peaks 1060
cm–1 (1051 in our case) and 724 cm–1 (727 in our case) are
assigned to the C–N bond and Cl– ion vibrational bands,
respectively (Emam and El-Hefny, 2023). In the spectrum
of the loaded organic phase, peaks 1051 and 727 cm–1
are shifted to 1021 and 715 cm–1 respectively, indicating
that extraction of the Ta and Nb oxalate complexes has
taken place. However, further investigations are required
to identify the nature of extracted Ta and Nb complexes.
The presence of a broad peak (3384 cm–1) in the loaded
organic phase spectrum is due to vibrations of O-H bonds,
indicating the presence of water. This presence is probably
attributed to the water molecule in the oxalic complexes of
Ta and Nb.
Separation Factors of Ta and Nb Against Fe, Mn and Ca
The separation factors of Ta and Nb against Fe, Ca and
Mn are shown in Figure 5. It can be seen that Ta and Nb
could be successfully separated to a high degree from these
impurities.
-1.2 -1.1 -1.0 -0.9 -0.8 -0.7 -0.6 -0.5
-1.4
-1.2
-1.0
-0.8
-0.6
-0.4
-0.2
0.0
0.2
0.4
0.6
Nb, y=2.4x+1.77, R2=0.9948
Ta, y=1.6x+0.63, R2=0.9574
log [Aliquat, M]
Figure 3. Linear relationship log D(Ta,Nb) =f(log [Aliquat®
336, M]) for the extraction of Ta and Nb from the aqueous
oxalic phase
0 5001000150020002500300035004000
Wavenumbers (cm-1)
(a)
(b)
Figure 4. IR spectra of an Aliquat® 336 loaded with Ta and
Nb oxalate complexes (a), and an organic phase of Aliquat®
336 (14% diluted in kerosene) -(b)
2967
2928
2860 1462
1383 1051 888
727
610
3384
2967 2860
1715 1684 1462 1383
905 803
715
688
541
1021
log
D M
Transmittance
(%)
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