XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2307
during the saponification process. Additionally, other peaks
in the spectra remained consistent between the oil samples
and their respective saponification products (region b).
These peaks correspond to the vibration of groups such as
=C-H cis-, -C-H (CH2). The findings were found in great
agreement with previously published data (Derhy et al.,
2024, 2022 El-bahi et al., 2024).
Adsorption Assessment
Zeta potential measurements were conducted in this study
to assess the nature of interactions between the studied min-
erals and the FACs. Figure 8 shows the results of the zeta
potential measurements of FACs, mineral particles before
and after interaction with the collectors. As it is shown in
Figure 8-(A) both pure minerals exhibit a negative charge
at all studied pH values. This negative charge is converted
to a positive charge as the pH decreased and the isoelectric
points of fluorapatite and quartz occur respectively at pH
which was in good agreement with the literature (Wang et
al., 2020 Zhou et al., 2020). In Figure 8-(B), it is shown
that the zeta potential of the studied collectors exhibits a
negative charge that becomes more positive as pH decreases.
This change is likely due to the nature of fatty acid species: at
high pH, they exist predominantly as RCOO– ions, while at
acidic pH, they convert to their RCOOH form. This tran-
sition reduces the negative charge on the surface, resulting
in a less negative zeta potential(Vučinić et al., 2010). After
adding increasing dosages of collector solutions, significant
reductions are observed in apatite particles zeta potential.
After contact with 50mg/L FrOC, MOC, and ROC at pH
9, the zeta potential respectively dropped from –7.81 mV
to –55.63 mV, –40.56 mV, –38.53 mV. In contrast, a lower
decrease in quartz zeta potential is observed after interaction
with the previous FAC where the zeta potential dropped
from –49.66 mV to –65.11 mV, –56.36 mV, –54.56 mV
respectively after contact with FrOC, MOC, and ROC at
pH 9 Figure 8-(C, D)(de Oliveira et al., 2019 Santos et
al., 2022).
Fourier transform infrared spectroscopy (FTIR) was
used as a second tool to assess the adsorption of the stud-
ied reagents onto apatite and quartz surfaces. This surface
characterization allows to determine the different chemical
groups present in the surface after interaction with different
molecules. Figure 9 shows the FTIR spectra corresponding
to the studied minerals before and after interaction with
FAC at pH 6, 9, 12. As is shown in the figure, the charac-
teristic peaks related to the bare minerals are found in great
agreement with what have being reported in the literature.
The characteristic peaks of pure fluorapatite are found
approximately to 568 cm–1, 598 cm–1 743 cm–1, 959 cm–1,
1020 cm–1, and 1090 cm–1 (Yang et al., 2020), the first two
peaks correspond to the bending vibration of P-O while
Figure 7. FTIR spectra of the studied oil samples and their corresponding saponification products
during the saponification process. Additionally, other peaks
in the spectra remained consistent between the oil samples
and their respective saponification products (region b).
These peaks correspond to the vibration of groups such as
=C-H cis-, -C-H (CH2). The findings were found in great
agreement with previously published data (Derhy et al.,
2024, 2022 El-bahi et al., 2024).
Adsorption Assessment
Zeta potential measurements were conducted in this study
to assess the nature of interactions between the studied min-
erals and the FACs. Figure 8 shows the results of the zeta
potential measurements of FACs, mineral particles before
and after interaction with the collectors. As it is shown in
Figure 8-(A) both pure minerals exhibit a negative charge
at all studied pH values. This negative charge is converted
to a positive charge as the pH decreased and the isoelectric
points of fluorapatite and quartz occur respectively at pH
which was in good agreement with the literature (Wang et
al., 2020 Zhou et al., 2020). In Figure 8-(B), it is shown
that the zeta potential of the studied collectors exhibits a
negative charge that becomes more positive as pH decreases.
This change is likely due to the nature of fatty acid species: at
high pH, they exist predominantly as RCOO– ions, while at
acidic pH, they convert to their RCOOH form. This tran-
sition reduces the negative charge on the surface, resulting
in a less negative zeta potential(Vučinić et al., 2010). After
adding increasing dosages of collector solutions, significant
reductions are observed in apatite particles zeta potential.
After contact with 50mg/L FrOC, MOC, and ROC at pH
9, the zeta potential respectively dropped from –7.81 mV
to –55.63 mV, –40.56 mV, –38.53 mV. In contrast, a lower
decrease in quartz zeta potential is observed after interaction
with the previous FAC where the zeta potential dropped
from –49.66 mV to –65.11 mV, –56.36 mV, –54.56 mV
respectively after contact with FrOC, MOC, and ROC at
pH 9 Figure 8-(C, D)(de Oliveira et al., 2019 Santos et
al., 2022).
Fourier transform infrared spectroscopy (FTIR) was
used as a second tool to assess the adsorption of the stud-
ied reagents onto apatite and quartz surfaces. This surface
characterization allows to determine the different chemical
groups present in the surface after interaction with different
molecules. Figure 9 shows the FTIR spectra corresponding
to the studied minerals before and after interaction with
FAC at pH 6, 9, 12. As is shown in the figure, the charac-
teristic peaks related to the bare minerals are found in great
agreement with what have being reported in the literature.
The characteristic peaks of pure fluorapatite are found
approximately to 568 cm–1, 598 cm–1 743 cm–1, 959 cm–1,
1020 cm–1, and 1090 cm–1 (Yang et al., 2020), the first two
peaks correspond to the bending vibration of P-O while
Figure 7. FTIR spectra of the studied oil samples and their corresponding saponification products