XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2635
dosages in amine but seems to be significantly affected at
higher dosages in amines (600 g·t–1). Also, the WO3
recovery depends strongly on the amine dosage, values of
more than 90% being attained for more than 700 g·t–1.
Weak interactions are exhibited between the amine dos-
age and the pH except for high amine dosages. Besides, the
WO3 grade increases when the pH increases or decreases,
with a minimum around pH 3. This is not consistent with
the surface charge values of scheelite, fluorite, and silicates
since increasing the pH should lead to a stronger flotation
of all the gangue minerals and, therefore, a decrease in the
WO3 grade (Figure 4).
DISCUSSION
Second Flotation
Optimized tests were selected and were subjected to the
second flotation stage. After the removal of fluorite, the
mineral being the main issue for recovery of scheelite, the
concentrate is submitted to the usual flotation route using
fatty acids, to recover selectively scheelite from the siliceous
gangue minerals. Results are displayed in Table 2.
From Table 2, it appears that one test shows promis-
ing results, with a WO3 grade of about 2.0%, testifying
an enrichment ratio above 2 for a recovery of about 66%
WO3. Considering the two flotation stages, the final prod-
uct has a grade of about 2% W for a recovery of about
43% (Table 2). Such results are close to the one obtained
by Foucaud and co-workers, where using organic molecules
(citric acid, tannin, lignosulfonate, etc.), where close grades
were obtained for recovery around 40% WO3 (Foucaud et
al., 2019b). Several hypotheses can explain this result (i)
the proposed flowsheet relies on a good depression of fluo-
rite, which means that during the first flotation stage, prod-
ucts with high WO3 recoveries are expected, even with low
enrichment ratios. Here, the product selected had a good
enrichment ratio for a satisfactory recovery. (ii) The reagents
dosages selected might be out of range of the optimal ones.
(iii) Base the reagent designs on the colloidal properties of
Table 2. Second flotation stage carried out on optimal products
pH Oleate, g·t–1 Depressant Dosage, g·t–1 Grade, %WO3 WO3 Stage Recovery, %WO3 Global Recovery, %
10 300 4000 1.35 52.39 44.82
10 300 4000 2.00 66.28 43.00
Figure 4.
dosages in amine but seems to be significantly affected at
higher dosages in amines (600 g·t–1). Also, the WO3
recovery depends strongly on the amine dosage, values of
more than 90% being attained for more than 700 g·t–1.
Weak interactions are exhibited between the amine dos-
age and the pH except for high amine dosages. Besides, the
WO3 grade increases when the pH increases or decreases,
with a minimum around pH 3. This is not consistent with
the surface charge values of scheelite, fluorite, and silicates
since increasing the pH should lead to a stronger flotation
of all the gangue minerals and, therefore, a decrease in the
WO3 grade (Figure 4).
DISCUSSION
Second Flotation
Optimized tests were selected and were subjected to the
second flotation stage. After the removal of fluorite, the
mineral being the main issue for recovery of scheelite, the
concentrate is submitted to the usual flotation route using
fatty acids, to recover selectively scheelite from the siliceous
gangue minerals. Results are displayed in Table 2.
From Table 2, it appears that one test shows promis-
ing results, with a WO3 grade of about 2.0%, testifying
an enrichment ratio above 2 for a recovery of about 66%
WO3. Considering the two flotation stages, the final prod-
uct has a grade of about 2% W for a recovery of about
43% (Table 2). Such results are close to the one obtained
by Foucaud and co-workers, where using organic molecules
(citric acid, tannin, lignosulfonate, etc.), where close grades
were obtained for recovery around 40% WO3 (Foucaud et
al., 2019b). Several hypotheses can explain this result (i)
the proposed flowsheet relies on a good depression of fluo-
rite, which means that during the first flotation stage, prod-
ucts with high WO3 recoveries are expected, even with low
enrichment ratios. Here, the product selected had a good
enrichment ratio for a satisfactory recovery. (ii) The reagents
dosages selected might be out of range of the optimal ones.
(iii) Base the reagent designs on the colloidal properties of
Table 2. Second flotation stage carried out on optimal products
pH Oleate, g·t–1 Depressant Dosage, g·t–1 Grade, %WO3 WO3 Stage Recovery, %WO3 Global Recovery, %
10 300 4000 1.35 52.39 44.82
10 300 4000 2.00 66.28 43.00
Figure 4.