XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1805
dissolution rate of Fe was low under the condition of the
low amount of leaching acid. Suspension oxidation roasting
pretreatment could reduce the concentration of impurity
elements through the amount of leaching acid and reduce
the difficulty of subsequent extraction operations.
In general, the lattice of the main vanadium-bearing
minerals was destroyed in the suspension oxidation roasting
process(Yuan et al., 2020 Zhang et al., 2020). It promoted
the release of central vanadium atoms and enhanced the
leaching effect. Meanwhile, it could promote the decompo-
sition of calcite, reduce acid dosage, improve the
production continuity, and decrease the solubility of
impurity element Fe.
Microstructure Evolution
SEM-EDS analysis was used to observe the microstruc-
ture evolution of samples after leached and investigated
the mechanism of enhanced vanadium extraction by sus-
pension oxidation roasting. SEM images of direct leach-
ing residues and suspension oxidation pretreatment were
displayed in Figure 9 and Figure 10, respectively. As shown
in Figure 9(a), it was a Quartz and Mica associated par-
ticles because the elements enrichment region of O, Si
(Area 1), and O, Al, Si, K (Area 2) elements were almost
coincident. The internal surface of quartz was dense while
cracks appeared on the surface of mica. In addition, the
distribution of V, analyzed by EDS area scan, indicated that
the vanadium was not efficiently leached under the condi-
tion of 15 wt.% with 5 wt.% CaF2. In addition, as shown
in Area 3 in Figure 9(b) and Area 4 and 5 in Figure 9(c),
more cracks and holes appeared on the surface of the parti-
cle with the increase of direct leaching acid dosage. During
the direct acid leaching process, CaF2 as a leaching aid was
added to the system. CaF2 reacted with H2SO4 generat-
ing HF. HF could destroy the silicates and aluminosilicate
minerals to enhance the vanadium extraction. However,
the cracks just appeared at the edge of the particle while the
particle center was still dense. The penetration depth of 35
wt.% with 5 wt.% CaF2 was still shallow(Li et al., 2021).
Figure 10 shown the microstructure of roasted product
residues. The results of the EDS area scan indicated that
Area 1 was a crack in the structure of aluminosilicate, and
the particle became loose. Areas 2 and 3 were dense quartz
particles. According to the distribution of V, the vanadium
was efficiently leached. After being roasted, the structure
of aluminosilicate was transformed from a layer structure
into a loose and porous structure. The porous structure
will improve the mass transfer efficiency and accelerate
the exchange of H+ with V(IV) or V(V). Compared with
direct acid leaching, the penetration depth of sulfuric acid
into particles was deeper. Therefore, suspension oxidation
(a) a, feed ore b, feed ore residue–20 wt.% c, feed ore residue–30 wt.% d, roasted product e, roasted product residue–5 wt.% f,
roasted product residur–10 wt.% (b) foam layer generated in feed ore leaching process
Figure 8. XRD pattern of different sample and leaching image
dissolution rate of Fe was low under the condition of the
low amount of leaching acid. Suspension oxidation roasting
pretreatment could reduce the concentration of impurity
elements through the amount of leaching acid and reduce
the difficulty of subsequent extraction operations.
In general, the lattice of the main vanadium-bearing
minerals was destroyed in the suspension oxidation roasting
process(Yuan et al., 2020 Zhang et al., 2020). It promoted
the release of central vanadium atoms and enhanced the
leaching effect. Meanwhile, it could promote the decompo-
sition of calcite, reduce acid dosage, improve the
production continuity, and decrease the solubility of
impurity element Fe.
Microstructure Evolution
SEM-EDS analysis was used to observe the microstruc-
ture evolution of samples after leached and investigated
the mechanism of enhanced vanadium extraction by sus-
pension oxidation roasting. SEM images of direct leach-
ing residues and suspension oxidation pretreatment were
displayed in Figure 9 and Figure 10, respectively. As shown
in Figure 9(a), it was a Quartz and Mica associated par-
ticles because the elements enrichment region of O, Si
(Area 1), and O, Al, Si, K (Area 2) elements were almost
coincident. The internal surface of quartz was dense while
cracks appeared on the surface of mica. In addition, the
distribution of V, analyzed by EDS area scan, indicated that
the vanadium was not efficiently leached under the condi-
tion of 15 wt.% with 5 wt.% CaF2. In addition, as shown
in Area 3 in Figure 9(b) and Area 4 and 5 in Figure 9(c),
more cracks and holes appeared on the surface of the parti-
cle with the increase of direct leaching acid dosage. During
the direct acid leaching process, CaF2 as a leaching aid was
added to the system. CaF2 reacted with H2SO4 generat-
ing HF. HF could destroy the silicates and aluminosilicate
minerals to enhance the vanadium extraction. However,
the cracks just appeared at the edge of the particle while the
particle center was still dense. The penetration depth of 35
wt.% with 5 wt.% CaF2 was still shallow(Li et al., 2021).
Figure 10 shown the microstructure of roasted product
residues. The results of the EDS area scan indicated that
Area 1 was a crack in the structure of aluminosilicate, and
the particle became loose. Areas 2 and 3 were dense quartz
particles. According to the distribution of V, the vanadium
was efficiently leached. After being roasted, the structure
of aluminosilicate was transformed from a layer structure
into a loose and porous structure. The porous structure
will improve the mass transfer efficiency and accelerate
the exchange of H+ with V(IV) or V(V). Compared with
direct acid leaching, the penetration depth of sulfuric acid
into particles was deeper. Therefore, suspension oxidation
(a) a, feed ore b, feed ore residue–20 wt.% c, feed ore residue–30 wt.% d, roasted product e, roasted product residue–5 wt.% f,
roasted product residur–10 wt.% (b) foam layer generated in feed ore leaching process
Figure 8. XRD pattern of different sample and leaching image