XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2655
%.74 *.*
.***
x x
x x x
3 0.14 0 03
0 06 0.06
Li O
RotorSpeed
AirFlowRate RotorSpeed
2 desliming
desliming
=++
-+
Looking at the isolines plot makes it easy to identify
optimal location for all size fraction considered. Here for the
40–280µm size fraction, optimal separation occurs using
an air flow rate of 20 (u.a.) and a rotor speed of 925 rpm
with expected grade and recovery being of 3.83%Li2O and
90%Li2O, respectively. Thus the conditions studied in the
first DoE were not optimal for this size fraction.
Nonetheless, for the wider size fraction, further opti-
misation can be obtained. Grade of 3.68%Li2O for a
recovery of 78%Li2O can be obtained using an air flow
rate of 20 (u.a.) and a rotor speed of about 725 rpm for the
10–280µm size fraction (Figure 5). Using such conditions
increased grade by 0.46%Li2O and the recovery by 10%
compared to the physico-chemical properties DoE con-
sidering a desliming size of 10µm and an amine dosage of
150 g/ton. Thus, this DoE highlights the possible improve-
ment of the recovery of fine particles (10–40µm).
However, as for physico-chemical properties, calculat-
ing the yields considering the whole flowsheet impacts the
lithium recoveries. The recovery surface response is dis-
played along with the isolines plot in Figure 6.
From this figure, the only impact on the responses of
the DoE is the recovery that is decreased for all samples.
This leads to a great impact as recovery for the 40–280µm
optimal point is reduced from 90%Li2O to 72.8%Li2O.
Same observation can be done for desliming size ranging
from 10 to 63 µm.
DISCUSSIONS
Another way to take a deeper look into the design of experi-
ments is to consider the PSDs of floated products compared
to their separation feed. They are displayed in Figure 7 for
all tests of the physico-chemical conditions design of exper-
iments carried out.
From this figure, several observations on the separa-
tion process can be assessed. For the widest size range, i.e.,
10–280µm, PSDs of flotation concentrates are usually finer
than the flotation feed. Thus, such behaviour can be related
to entrainment of material in the concentrate. This hypoth-
esis is also in agreement with the enrichment ratio of the
light green product, which is the smallest of the whole DoE.
Nevertheless, the other floated product either have PSDs
close to the feed or a bit coarser. These products correspond
to low amine dosages and low pH values, respectively. Such
an observation attest that lepidolite is better floated at
acidic pH values. However, in this restricted range of pH
values, this variable was only slightly significant, compared
to both amine dosage and desliming size. In conclusion, for
this size fraction the separation efficiency is mainly related
to the amine dosage, which may cause entrainment of fine
particles in the concentrate.
For the two remaining size fractions, close observations
can be done. Most products have similar PSDs compared
to their flotation separation feed. This suggest that flota-
tion is not selective on particle size for such size fraction,
even with various collector dosages and pH values. Thus, it
seems that the separation efficiency mostly relies on good
physico-chemical conditions, rather than favoured hydro-
dynamic conditions in the flotation cell. This hypothesis, if
confirmed has strong implications for the concentration of
lepidolite from its gangue minerals.
CONCLUSIONS
This comprehensive study focused on the physico-chemical
conditions needed to achieve a good separation efficiency of
lepidolite from its gangue minerals. This was done by con-
sidering the pH values, the amine dosage for flotation but
also the desliming size of flotation feeds. Prepared through
a successful pilot test, the feed for separation showed a clas-
sic grindability behaviour with lepidolite being the coarsest
mineral, followed by silicates and then metallic oxides (cas-
siterite, columbo-tantalite) and phosphates. This suggests
that, after desliming, the expected floated products should
be a bit coarser than their feeds.
Flotation tests, carried out through the design of
experiments methodology showed that the most significant
parameters are both the desliming size and the amine dos-
age. In a less important way, pH value can be noted as a
significant parameter. This last observation can be related to
the narrowed pH value studied. With both low dosages and
medium to coarse desliming sizes, excellent Li2O grades
can be obtained.
REFERENCES
Cathelineau, M., 1986. The Hydrothermal Alkali
Metasomatism Effects on Granitic Rocks: Quartz
Dissolution and Related Subsolidus Changes.
Journal of Petrology 27, 945–965. doi: 10.1093/
petrology/27.4.945.
Chen, C., Song, Y.S., Li, W.J., Qu, W., Cai, L.L., Chen, Y.,
2015. Study on Flotation Separation of Muscovite
and Kaolinite. AMR 1092–1093, 1474–1479. doi:
10.4028/www.scientific.net/AMR.1092-1093.1474.
%.74 *.*
.***
x x
x x x
3 0.14 0 03
0 06 0.06
Li O
RotorSpeed
AirFlowRate RotorSpeed
2 desliming
desliming
=++
-+
Looking at the isolines plot makes it easy to identify
optimal location for all size fraction considered. Here for the
40–280µm size fraction, optimal separation occurs using
an air flow rate of 20 (u.a.) and a rotor speed of 925 rpm
with expected grade and recovery being of 3.83%Li2O and
90%Li2O, respectively. Thus the conditions studied in the
first DoE were not optimal for this size fraction.
Nonetheless, for the wider size fraction, further opti-
misation can be obtained. Grade of 3.68%Li2O for a
recovery of 78%Li2O can be obtained using an air flow
rate of 20 (u.a.) and a rotor speed of about 725 rpm for the
10–280µm size fraction (Figure 5). Using such conditions
increased grade by 0.46%Li2O and the recovery by 10%
compared to the physico-chemical properties DoE con-
sidering a desliming size of 10µm and an amine dosage of
150 g/ton. Thus, this DoE highlights the possible improve-
ment of the recovery of fine particles (10–40µm).
However, as for physico-chemical properties, calculat-
ing the yields considering the whole flowsheet impacts the
lithium recoveries. The recovery surface response is dis-
played along with the isolines plot in Figure 6.
From this figure, the only impact on the responses of
the DoE is the recovery that is decreased for all samples.
This leads to a great impact as recovery for the 40–280µm
optimal point is reduced from 90%Li2O to 72.8%Li2O.
Same observation can be done for desliming size ranging
from 10 to 63 µm.
DISCUSSIONS
Another way to take a deeper look into the design of experi-
ments is to consider the PSDs of floated products compared
to their separation feed. They are displayed in Figure 7 for
all tests of the physico-chemical conditions design of exper-
iments carried out.
From this figure, several observations on the separa-
tion process can be assessed. For the widest size range, i.e.,
10–280µm, PSDs of flotation concentrates are usually finer
than the flotation feed. Thus, such behaviour can be related
to entrainment of material in the concentrate. This hypoth-
esis is also in agreement with the enrichment ratio of the
light green product, which is the smallest of the whole DoE.
Nevertheless, the other floated product either have PSDs
close to the feed or a bit coarser. These products correspond
to low amine dosages and low pH values, respectively. Such
an observation attest that lepidolite is better floated at
acidic pH values. However, in this restricted range of pH
values, this variable was only slightly significant, compared
to both amine dosage and desliming size. In conclusion, for
this size fraction the separation efficiency is mainly related
to the amine dosage, which may cause entrainment of fine
particles in the concentrate.
For the two remaining size fractions, close observations
can be done. Most products have similar PSDs compared
to their flotation separation feed. This suggest that flota-
tion is not selective on particle size for such size fraction,
even with various collector dosages and pH values. Thus, it
seems that the separation efficiency mostly relies on good
physico-chemical conditions, rather than favoured hydro-
dynamic conditions in the flotation cell. This hypothesis, if
confirmed has strong implications for the concentration of
lepidolite from its gangue minerals.
CONCLUSIONS
This comprehensive study focused on the physico-chemical
conditions needed to achieve a good separation efficiency of
lepidolite from its gangue minerals. This was done by con-
sidering the pH values, the amine dosage for flotation but
also the desliming size of flotation feeds. Prepared through
a successful pilot test, the feed for separation showed a clas-
sic grindability behaviour with lepidolite being the coarsest
mineral, followed by silicates and then metallic oxides (cas-
siterite, columbo-tantalite) and phosphates. This suggests
that, after desliming, the expected floated products should
be a bit coarser than their feeds.
Flotation tests, carried out through the design of
experiments methodology showed that the most significant
parameters are both the desliming size and the amine dos-
age. In a less important way, pH value can be noted as a
significant parameter. This last observation can be related to
the narrowed pH value studied. With both low dosages and
medium to coarse desliming sizes, excellent Li2O grades
can be obtained.
REFERENCES
Cathelineau, M., 1986. The Hydrothermal Alkali
Metasomatism Effects on Granitic Rocks: Quartz
Dissolution and Related Subsolidus Changes.
Journal of Petrology 27, 945–965. doi: 10.1093/
petrology/27.4.945.
Chen, C., Song, Y.S., Li, W.J., Qu, W., Cai, L.L., Chen, Y.,
2015. Study on Flotation Separation of Muscovite
and Kaolinite. AMR 1092–1093, 1474–1479. doi:
10.4028/www.scientific.net/AMR.1092-1093.1474.