XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1619
and then tends to constant with the increase of the leaching
duration. As is presented in Figure 4, the leaching ratio of
vanadium for UAL is 61.76% at 1 h, while it is only 21.35
at the same time via CL. In the CL system, the optimal
leaching ratio of vanadium reaches as 78.06% after leach-
ing for 10 h. Nevertheless, the maximal vanadium leaching
ratio attains 89.27% at leaching time of 3 h. The results
demonstrates that the introduction of introduction of
ultrasound and NaClO3 can not only obviously increase
the leaching recovery of vanadium, but also shorten the
leaching duration. The remarkable advantages brought by
ultrasound may be ascribed to the enhanced mass transfer
and diffusion of the lixiviants through the pores and cracks
of the particles formed by the action of cavitation (Chang
et al., 2017 Chen et al., 2021).
Leaching Kinetics Of Vanadium in CL and
UAL Systems
The fitting of leaching kinetics of vanadium in CL and
UAL systems was carried out based on the shrinking core
model (SCM)(He et al., 2018). It is well accepted that the
leaching rate of metals is commonly controlled by product
diffusion control (Eq. (2)), chemical reaction control (Eq.
(3)) or mixed control (product diffusion and chemical reac-
tion) (Eq. (4)) with the liquid film diffusion be excluded in
the intensive stirring and ultrasound irradiation leaching
process (Ma et al., 2017).
k t L Lh 1 3^1 2^1
p
3
2 =--+-h (2)
k t Lh 1 1
c
3
1 =--^(3)
ln^1 k t L Lh- 3
1 1
m
3
1 =-+--^1 h (4)
where L is the vanadium leaching ratio (%)t is the leach-
ing time of vanadium (min) kp, kc and km is the reaction
rate constant for product diffusion control, chemical reac-
tion control and mixed control (min–1), severally.
The fitting outcomes for vanadium leaching kinetics
process via SCM models are displayed in Figure 5, and
corresponding fitting reaction rate constants are listed as
Table 2. The results demonstrate that the leaching process
of vanadium is controlled by product diffusion for these
two leaching systems. In the meantime, it can be obtained
from Table 2 that the leaching reaction rate of vanadium
in the presence of ultrasound (2.89×10–3 min–1) is higher
than that in the absence of ultrasound (5.8×10–4 min–1),
indicating that the ultrasound can obviously accelerate the
leaching reaction rate compared to that in the CL process
(He et al., 2018 Ma et al., 2017).
Phase Transformation of Vanadium-Bearing Shale
The phase transformations of the vanadium-bearing shale
with and without ultrasound were analyzed by XRD, which
is presented in Figure 6. It is distinct that the diffraction
Figure 3. Effect of leaching temperature on the leaching ratio of vanadium (NaClO
3 dosage of
9 wt.%, H
2 SO
4 concentration of 20 vol.%, leaching time of 30 min, ultrasound power of 150 W,
liquid to solid ratio of 3:1 mL/g)
and then tends to constant with the increase of the leaching
duration. As is presented in Figure 4, the leaching ratio of
vanadium for UAL is 61.76% at 1 h, while it is only 21.35
at the same time via CL. In the CL system, the optimal
leaching ratio of vanadium reaches as 78.06% after leach-
ing for 10 h. Nevertheless, the maximal vanadium leaching
ratio attains 89.27% at leaching time of 3 h. The results
demonstrates that the introduction of introduction of
ultrasound and NaClO3 can not only obviously increase
the leaching recovery of vanadium, but also shorten the
leaching duration. The remarkable advantages brought by
ultrasound may be ascribed to the enhanced mass transfer
and diffusion of the lixiviants through the pores and cracks
of the particles formed by the action of cavitation (Chang
et al., 2017 Chen et al., 2021).
Leaching Kinetics Of Vanadium in CL and
UAL Systems
The fitting of leaching kinetics of vanadium in CL and
UAL systems was carried out based on the shrinking core
model (SCM)(He et al., 2018). It is well accepted that the
leaching rate of metals is commonly controlled by product
diffusion control (Eq. (2)), chemical reaction control (Eq.
(3)) or mixed control (product diffusion and chemical reac-
tion) (Eq. (4)) with the liquid film diffusion be excluded in
the intensive stirring and ultrasound irradiation leaching
process (Ma et al., 2017).
k t L Lh 1 3^1 2^1
p
3
2 =--+-h (2)
k t Lh 1 1
c
3
1 =--^(3)
ln^1 k t L Lh- 3
1 1
m
3
1 =-+--^1 h (4)
where L is the vanadium leaching ratio (%)t is the leach-
ing time of vanadium (min) kp, kc and km is the reaction
rate constant for product diffusion control, chemical reac-
tion control and mixed control (min–1), severally.
The fitting outcomes for vanadium leaching kinetics
process via SCM models are displayed in Figure 5, and
corresponding fitting reaction rate constants are listed as
Table 2. The results demonstrate that the leaching process
of vanadium is controlled by product diffusion for these
two leaching systems. In the meantime, it can be obtained
from Table 2 that the leaching reaction rate of vanadium
in the presence of ultrasound (2.89×10–3 min–1) is higher
than that in the absence of ultrasound (5.8×10–4 min–1),
indicating that the ultrasound can obviously accelerate the
leaching reaction rate compared to that in the CL process
(He et al., 2018 Ma et al., 2017).
Phase Transformation of Vanadium-Bearing Shale
The phase transformations of the vanadium-bearing shale
with and without ultrasound were analyzed by XRD, which
is presented in Figure 6. It is distinct that the diffraction
Figure 3. Effect of leaching temperature on the leaching ratio of vanadium (NaClO
3 dosage of
9 wt.%, H
2 SO
4 concentration of 20 vol.%, leaching time of 30 min, ultrasound power of 150 W,
liquid to solid ratio of 3:1 mL/g)