1812 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
of carbonaceous shale was scattered on the porous quartz
plate of the roasting tube (Ф 50 mm). After the gas pipe
was connected, the roasting tube was put into the verti-
cal heating furnace. According to the set gas flow and oxy-
gen content, the gas of O2 and N2 (purity of 99.99%) was
introduced to start the primary oxidation roasting. When
roasting was finished, the sample was used for detection
and further acid-leaching experiment. Thus the appropriate
primary oxygen roasting conditions were selected. Based on
this, the second stage of roasting (high-temperature reoxi-
dation roasting) was carried out. Similarly, 25 g of primary
roasted product was put into a roasting tube. The experi-
mental procedure is the same as that of the primary oxygen
roasting. Finally, the cooled roasted products were used for
detection and further acid-leaching experiment.
During the acid-leaching experiment, 15 g of primary
roasted product, a certain amount of deionized water, and
sulfuric acid were put into a beaker. Constant leaching tem-
perature was provided by a water bath (DF-101S, China).
The experimental conditions were fixed: 20 wt% sulfuric
acid, a liquid-solid ratio of 6:1, a leaching temperature of
90 °C, and a leaching time of 3 h. When the leaching was
completed, the leaching product was washed three times,
then filtered, dried, and weighed. The grade of V2O5 in the
leaching residue was tested, then the leaching rate of V2O5.
Analytical methods
X-ray fluorescence spectrometer (XRF) and chemical com-
position analysis were used for chemical composition analy-
sis. And the mineral compositions of roasted products were
studied by X-ray diffraction analysis (XRD, Panalytical X
Pertpro, Holland), with the conditions of 40 kV tube volt-
age, Cu target, and 2θ of 5°~75°. Then the particle size was
analyzed by Micromeritics TriStar II 3020 (Version 3.02,
American). Scanning electron microscopy with energy dis-
persive spectroscopy was used for sample morphology and
elements analysis (SEM-EDS, Zeiss Ultra Plus, Germany,
and OXFORD X-MAXN, England). Then the thermal
analyzer was used for thermogravimetric analysis with con-
ditions of air atmosphere, temperature range of 20~1300
°C, and heating rate of 18 °C/min. Fourier transform infra-
red spectroscopy was used (FTIR, Nicolet 380, American),
at conditions of KBr tablet, scanning wave 400~4000 cm–1,
and resolution of 4 cm–1.
RESULTS AND DISCUSSION
Effect of particle size
The roasting particle size is an important factor affecting
the reaction conversion and reaction rate. To determine the
reasonable roasting particle size, the roasting particle size
experiment of carbonaceous shale was carried out. The dry
grinding experiment was carried out with an experimental
ball mill to investigate the relationship between grinding
particle size and grinding time. The grinding curve of par-
ticle size was determined. Its results are shown in Table 2
and Figure 2.
Further, the carbon content and V2O5 leaching rate of
roasted products with –0.074 mm content accounting for
38.9%, 58.34%, 75.36%, 88.57%, 95.59%, and 98.3%
were investigated (roasting conditions: temperature 800 °C,
time 1 h, gas volume 600 ml/min, oxygen content 21%).
The results are shown in Figure 3. With the reduction of
the particle size of carbonaceous shale, the leaching rate
of V2O5 shows a trend of first increasing and then gentle,
and the carbon content shows a trend of first decreasing
and then gentle. When the content of roasted particle size
increased from 38.9% to 95.59% from –0.074 mm, the
leaching rate and decarburization rate of V2O5 increased
significantly. The vanadium leaching rate increased from
40.81% to 52.11%, and the carbon content decreased
Table 2. Effect of grinding time on grinding fineness
Grinding time (min) 5 9 13 17 21 25
–0.074 mm content (%)38.90 58.34 75.36 88.57 95.59 98.30
Figure 2. Characteristic curve of grinding particle size for
carbonaceous shale
of carbonaceous shale was scattered on the porous quartz
plate of the roasting tube (Ф 50 mm). After the gas pipe
was connected, the roasting tube was put into the verti-
cal heating furnace. According to the set gas flow and oxy-
gen content, the gas of O2 and N2 (purity of 99.99%) was
introduced to start the primary oxidation roasting. When
roasting was finished, the sample was used for detection
and further acid-leaching experiment. Thus the appropriate
primary oxygen roasting conditions were selected. Based on
this, the second stage of roasting (high-temperature reoxi-
dation roasting) was carried out. Similarly, 25 g of primary
roasted product was put into a roasting tube. The experi-
mental procedure is the same as that of the primary oxygen
roasting. Finally, the cooled roasted products were used for
detection and further acid-leaching experiment.
During the acid-leaching experiment, 15 g of primary
roasted product, a certain amount of deionized water, and
sulfuric acid were put into a beaker. Constant leaching tem-
perature was provided by a water bath (DF-101S, China).
The experimental conditions were fixed: 20 wt% sulfuric
acid, a liquid-solid ratio of 6:1, a leaching temperature of
90 °C, and a leaching time of 3 h. When the leaching was
completed, the leaching product was washed three times,
then filtered, dried, and weighed. The grade of V2O5 in the
leaching residue was tested, then the leaching rate of V2O5.
Analytical methods
X-ray fluorescence spectrometer (XRF) and chemical com-
position analysis were used for chemical composition analy-
sis. And the mineral compositions of roasted products were
studied by X-ray diffraction analysis (XRD, Panalytical X
Pertpro, Holland), with the conditions of 40 kV tube volt-
age, Cu target, and 2θ of 5°~75°. Then the particle size was
analyzed by Micromeritics TriStar II 3020 (Version 3.02,
American). Scanning electron microscopy with energy dis-
persive spectroscopy was used for sample morphology and
elements analysis (SEM-EDS, Zeiss Ultra Plus, Germany,
and OXFORD X-MAXN, England). Then the thermal
analyzer was used for thermogravimetric analysis with con-
ditions of air atmosphere, temperature range of 20~1300
°C, and heating rate of 18 °C/min. Fourier transform infra-
red spectroscopy was used (FTIR, Nicolet 380, American),
at conditions of KBr tablet, scanning wave 400~4000 cm–1,
and resolution of 4 cm–1.
RESULTS AND DISCUSSION
Effect of particle size
The roasting particle size is an important factor affecting
the reaction conversion and reaction rate. To determine the
reasonable roasting particle size, the roasting particle size
experiment of carbonaceous shale was carried out. The dry
grinding experiment was carried out with an experimental
ball mill to investigate the relationship between grinding
particle size and grinding time. The grinding curve of par-
ticle size was determined. Its results are shown in Table 2
and Figure 2.
Further, the carbon content and V2O5 leaching rate of
roasted products with –0.074 mm content accounting for
38.9%, 58.34%, 75.36%, 88.57%, 95.59%, and 98.3%
were investigated (roasting conditions: temperature 800 °C,
time 1 h, gas volume 600 ml/min, oxygen content 21%).
The results are shown in Figure 3. With the reduction of
the particle size of carbonaceous shale, the leaching rate
of V2O5 shows a trend of first increasing and then gentle,
and the carbon content shows a trend of first decreasing
and then gentle. When the content of roasted particle size
increased from 38.9% to 95.59% from –0.074 mm, the
leaching rate and decarburization rate of V2O5 increased
significantly. The vanadium leaching rate increased from
40.81% to 52.11%, and the carbon content decreased
Table 2. Effect of grinding time on grinding fineness
Grinding time (min) 5 9 13 17 21 25
–0.074 mm content (%)38.90 58.34 75.36 88.57 95.59 98.30
Figure 2. Characteristic curve of grinding particle size for
carbonaceous shale