1580 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
Flotation Reagents
The collector used for flotation is a 3-(isodecyloxy)propyl-
amine with a purity of 97% provided by Ceca (France).
This ether amine was solubilized using analytical grade ace-
tic acid (Sigma Aldrich, USA) in a 1:1 molar ratio. The pH
modifiers used were H2SO4 (97%, Sigma-Aldrich, USA)
and NaOH (99%, VWR, USA). All reagents were pre-
pared using Milli-Q water with a resistivity of 18.2 MΩ/
cm (Aquadem, Veolia, France).
Flotation Tests
Flotation tests were conducted using an LA-500 rotor-sta-
tor apparatus (Agitair) with a 1.5 L cell fed with 500 g of
ore samples. Conditioning and flotation were performed
in the flotation cell with solid-to-liquid ratios of 66%
and 25%, respectively, at a rotor speed of approximately
800 rpm. The tests were conducted at room temperature
(20–25°C). Ore samples were conditioned with water and
400 g/ton of etheramine for 5 minutes. The pH was moni-
tored using a pH meter 3310 equipped with a pH sentix
41 probe (WTW, Germany). The pH was adjusted to a
value of approximately 2 (± 0.1). The air flow rate during
flotation was set at approximately 0.27 m3/h. Foam was
manually collected at intervals of approximately 2 seconds
for 8 minutes.
RESULTS
Automated Mineralogy Based on µXRF on Thin
Section Samples
Optical Microscopy and Its Limits
A representative thin section of the Beauvoir granite,
scanned in polarized and analyzed light, is depicted in
Figure 1. From this thin section, it is possible to determine
the abundant presence of quartz, albite, and lepidolite-mus-
covite (Figure 1). In a less significant proportion, potassium
feldspar and phosphate are identifiable.
However, this thin section does not allow for or makes
it difficult to differentiate between lepidolite and musco-
vite. Only the literature on the Beauvoir granite provides
clues to the possible differentiation of these two minerals.
Thus, muscovite is mainly present in the form of micro-
muscovite, formed by the alteration of the Beauvoir gran-
ite, either from feldspars or from lepidolite (Demeusy et al.,
2023 Kosakevitch, 1976).
The identification and differentiation of these two
minerals are key challenges in the context of valorizing
this deposit. Since lepidolite is the main carrier of lithium,
realistic quantification of this mineral is necessary to limit
under- or overestimations of lithium content. Additionally,
as these two minerals have similar flotation behaviors, the
exact quantification of muscovite and lepidolite allows for
understanding the theoretical limits during flotation stages
(dilution of lithium content by muscovite) (Korbel et al.,
2023).
µXRF: Falsed Coloured Classified Image
Muscovite and lepidolite can be differentiated by variations
in the occupancy of their sites: tetrahedral, octahedral, and
interfoliate. These differences are highlighted in Table 1.
From this information, several key points for the identi-
fication and quantification of these two mineral phases by
automated mineralogy method can be defined. The pres-
ence of lithium in the octahedral sites of lepidolite is the
main criterion for differentiating the two micas. However,
lithium cannot be quantified by X-ray fluorescence spec-
troscopy. Secondly, it has been shown by numerous authors
that lepidolite and muscovite have different contents of
Figure 1. Thin section of the Beauvoir granite observed in
cross polarized light. Qz =quartz, Ab =albite, Kfd =feldpath
potassique, Lpd =lepidolite et Msc =muscovite
Flotation Reagents
The collector used for flotation is a 3-(isodecyloxy)propyl-
amine with a purity of 97% provided by Ceca (France).
This ether amine was solubilized using analytical grade ace-
tic acid (Sigma Aldrich, USA) in a 1:1 molar ratio. The pH
modifiers used were H2SO4 (97%, Sigma-Aldrich, USA)
and NaOH (99%, VWR, USA). All reagents were pre-
pared using Milli-Q water with a resistivity of 18.2 MΩ/
cm (Aquadem, Veolia, France).
Flotation Tests
Flotation tests were conducted using an LA-500 rotor-sta-
tor apparatus (Agitair) with a 1.5 L cell fed with 500 g of
ore samples. Conditioning and flotation were performed
in the flotation cell with solid-to-liquid ratios of 66%
and 25%, respectively, at a rotor speed of approximately
800 rpm. The tests were conducted at room temperature
(20–25°C). Ore samples were conditioned with water and
400 g/ton of etheramine for 5 minutes. The pH was moni-
tored using a pH meter 3310 equipped with a pH sentix
41 probe (WTW, Germany). The pH was adjusted to a
value of approximately 2 (± 0.1). The air flow rate during
flotation was set at approximately 0.27 m3/h. Foam was
manually collected at intervals of approximately 2 seconds
for 8 minutes.
RESULTS
Automated Mineralogy Based on µXRF on Thin
Section Samples
Optical Microscopy and Its Limits
A representative thin section of the Beauvoir granite,
scanned in polarized and analyzed light, is depicted in
Figure 1. From this thin section, it is possible to determine
the abundant presence of quartz, albite, and lepidolite-mus-
covite (Figure 1). In a less significant proportion, potassium
feldspar and phosphate are identifiable.
However, this thin section does not allow for or makes
it difficult to differentiate between lepidolite and musco-
vite. Only the literature on the Beauvoir granite provides
clues to the possible differentiation of these two minerals.
Thus, muscovite is mainly present in the form of micro-
muscovite, formed by the alteration of the Beauvoir gran-
ite, either from feldspars or from lepidolite (Demeusy et al.,
2023 Kosakevitch, 1976).
The identification and differentiation of these two
minerals are key challenges in the context of valorizing
this deposit. Since lepidolite is the main carrier of lithium,
realistic quantification of this mineral is necessary to limit
under- or overestimations of lithium content. Additionally,
as these two minerals have similar flotation behaviors, the
exact quantification of muscovite and lepidolite allows for
understanding the theoretical limits during flotation stages
(dilution of lithium content by muscovite) (Korbel et al.,
2023).
µXRF: Falsed Coloured Classified Image
Muscovite and lepidolite can be differentiated by variations
in the occupancy of their sites: tetrahedral, octahedral, and
interfoliate. These differences are highlighted in Table 1.
From this information, several key points for the identi-
fication and quantification of these two mineral phases by
automated mineralogy method can be defined. The pres-
ence of lithium in the octahedral sites of lepidolite is the
main criterion for differentiating the two micas. However,
lithium cannot be quantified by X-ray fluorescence spec-
troscopy. Secondly, it has been shown by numerous authors
that lepidolite and muscovite have different contents of
Figure 1. Thin section of the Beauvoir granite observed in
cross polarized light. Qz =quartz, Ab =albite, Kfd =feldpath
potassique, Lpd =lepidolite et Msc =muscovite