XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1813
from 0.176% to 0.034%. Therefore, carbonaceous shale
with –0.074 mm content accounting for 95.59% (grinding
time is 21 min) is considered to be the appropriate roasting
particle size.
Primary Oxidation Roasting
The carbon in carbonaceous shale is not conducive to the
oxidation and leaching of vanadium. Decarburization is an
important guarantee to improve the V2O5 leaching rate
in the process of vanadium extraction from carbonaceous
shale. Therefore, the primary oxidation roasting experiment
of carbonaceous shale was carried out. The effects of roast-
ing time and temperature on carbon content and V2O5
leaching rate were studied. Under the condition of the oxy-
gen content of 21% and total gas volume of 600 ml/min,
the V2O5 leaching rate and carbon content of the roasted
products were investigated when the roasting time was 0.25
h, 0.5 h, 0.75 h, and 1 h, and the roasting temperature was
450 °C, 500 °C, 550 °C, 600 °C, 650 °C, and 700 °C. The
experiment results are shown in Figure 4.
Figure 4(a) shows that the V2O5 leaching rate of
unburned carbonaceous shale was 32.66%, and the carbon
content was 9.31%. When the time increased from 0.25 h
to 0.5 h, the leaching rate of V2O5 increased from 37.64%
to 46.47%, and the carbon content decreased from 6.36%
to 3.70%. The leaching rate of V2O5 increased first and
then decreased, but the carbon content decreased gradu-
ally. When the time was extended to 1 h, the leaching rate
of V2O5 decreased to 38.25%, and the carbon content
decreased to 0.15%. The result shows that 0.5 h is the suit-
able condition for the primary oxidation roasting, and the
V2O5 leaching rate index is high at this time.
The effect of roasting temperature on decarburization
and leaching was given in Figure 4(b). When the tempera-
ture rose from 450 °C to 600 °C, the V2O5 leaching rate
increased from 37.64% to 46.47%, and the carbon con-
tent decreased from 3.79% to 3.52%. When the roasting
temperature continued to increase to 700 °C, the leaching
rate of V2O5 was about 46.47%, and the carbon content
was between 2.66% and 3.52%. According to the compre-
hensive roasting index, the optimum temperature for the
primary oxidation roasting was 650 °C and the optimum
time was 0.5 h with a leaching rate of 46.39%. Finally, the
primary oxidation roasting product was obtained with a Figure 3. Effect of carbon content and vanadium leaching
rate of particle size
Figure 4. Effect of roasting time and temperature on vanadium leaching and carbon content (a-roasting time, b-roasting
temperature)
from 0.176% to 0.034%. Therefore, carbonaceous shale
with –0.074 mm content accounting for 95.59% (grinding
time is 21 min) is considered to be the appropriate roasting
particle size.
Primary Oxidation Roasting
The carbon in carbonaceous shale is not conducive to the
oxidation and leaching of vanadium. Decarburization is an
important guarantee to improve the V2O5 leaching rate
in the process of vanadium extraction from carbonaceous
shale. Therefore, the primary oxidation roasting experiment
of carbonaceous shale was carried out. The effects of roast-
ing time and temperature on carbon content and V2O5
leaching rate were studied. Under the condition of the oxy-
gen content of 21% and total gas volume of 600 ml/min,
the V2O5 leaching rate and carbon content of the roasted
products were investigated when the roasting time was 0.25
h, 0.5 h, 0.75 h, and 1 h, and the roasting temperature was
450 °C, 500 °C, 550 °C, 600 °C, 650 °C, and 700 °C. The
experiment results are shown in Figure 4.
Figure 4(a) shows that the V2O5 leaching rate of
unburned carbonaceous shale was 32.66%, and the carbon
content was 9.31%. When the time increased from 0.25 h
to 0.5 h, the leaching rate of V2O5 increased from 37.64%
to 46.47%, and the carbon content decreased from 6.36%
to 3.70%. The leaching rate of V2O5 increased first and
then decreased, but the carbon content decreased gradu-
ally. When the time was extended to 1 h, the leaching rate
of V2O5 decreased to 38.25%, and the carbon content
decreased to 0.15%. The result shows that 0.5 h is the suit-
able condition for the primary oxidation roasting, and the
V2O5 leaching rate index is high at this time.
The effect of roasting temperature on decarburization
and leaching was given in Figure 4(b). When the tempera-
ture rose from 450 °C to 600 °C, the V2O5 leaching rate
increased from 37.64% to 46.47%, and the carbon con-
tent decreased from 3.79% to 3.52%. When the roasting
temperature continued to increase to 700 °C, the leaching
rate of V2O5 was about 46.47%, and the carbon content
was between 2.66% and 3.52%. According to the compre-
hensive roasting index, the optimum temperature for the
primary oxidation roasting was 650 °C and the optimum
time was 0.5 h with a leaching rate of 46.39%. Finally, the
primary oxidation roasting product was obtained with a Figure 3. Effect of carbon content and vanadium leaching
rate of particle size
Figure 4. Effect of roasting time and temperature on vanadium leaching and carbon content (a-roasting time, b-roasting
temperature)