XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1817
2022a). In addition, the weak absorption bands of 797
cm–1, 778 cm–1, and 694 cm–1 also belong to this vibration
(Yuan et al., 2019). The two deeply split bands at 510 cm–1
and 462 cm–1 belonged to Si-O bending vibration (Yuan
et al., 2015). The infrared spectra of high-temperature
reoxidation roasted products at different O2 contents have
significant differences. When the content of O2 increased
to 21%, the hydroxyl vibrational band obviously migrated
from 3442.02 cm–1 to 3421.92 cm–1. This indicated that
the hydroxyl structure in the structural water has changed.
When the content of O2 further increased to 35%, the
hydroxyl vibration band further migrates to 3410.49 cm–1.
At this time, the hydroxyl change in the sample was more
obvious. The change of hydroxyl structure was related to
the lattice damage of vanadium-bearing minerals (Bai et al.,
2022b Li et al., 2023). This showed that the lattice struc-
ture of vanadium-bearing minerals was gradually destroyed
with the increase in oxygen content. Because oxygen was
the reactant of the dehydroxylation process. This conclu-
sion is consistent with the trend of the oxygen condition
experiment. The analysis shows that increasing oxygen
content can promote the lattice damage effect of calcined
products.
Micromorphology of Carbonaceous Shale Surface
SEM analysis of carbonaceous shale raw ore, primary
oxidation roasting products, and high-temperature reoxi-
dation roasting products is shown in Figure 8. EDS spec-
trum analysis is also carried out synchronously, as shown
in Figure 8 and Table 4. Figure 8(a-b) shows the effect of
primary oxygen roasting on the morphology of carbona-
ceous shale. Figure 8(a) shows that the carbonaceous shale
particles were layered. The particle surface was smooth and
compact without holes. However, after roasting at 650 °C
for 0.5 h, the surface of the roasted product became uneven.
A large number of irregular cracks and holes appeared on
the surface of the particles, and the whole particle pre-
sented a loose and porous structure. Because the carbon
that was originally closely embedded with other minerals
was removed by primary oxidation roasting. It was valuable
because the porous structure was more conducive to gas-
solid and liquid-solid reactions. This showed the necessity
of primary oxidation roasting.
The morphology of the roasted products at 700 °C,
850 °C, and 1050 °C were shown in Figure 8(c-e). The
morphology and structure of particles in Figure 8(c) and
Figure 8(d) were similar to those in Figure 8(b). Both pre-
sented a honeycomb porous structure. Because carbon oxi-
dation played a decisive role in morphology. The carbon
in the primary oxidation roasting product was completely
removed, so the high-temperature roasting would not sig-
nificantly change the particle morphology unless sinter-
ing occurred. Figure 8(e) shows that a smooth and dense
“thin film” appeared on the surface of the roasted product
at 1050 °C, resulting in sintering (Yuan et al., 2020b Zhao
et al., 2018). Melting and adhesion occurred on the surface
of the particles, and a large number of holes were covered
by liquid molten substances. On the one hand, this molten
material contained vanadium, on the other hand, it sealed
the pores of particles, and the leaching of V2O5 was greatly
hindered. This sintering phenomenon confirmed the rea-
son why the temperature experiment results at 1050 °C
were poor.
The energy spectrum data in Figure 8 and Table 4
shows the element composition and proportion of each
sample. According to the data in Table 4, elements such
as Si, Al, O, C, Mg, V, S, and Fe are mainly contained in
position 1, indicating that this area contains quartz, mica,
carbonaceous, and pyrite. The mass fraction of element C
in position 2 decreased to 5.34%, 20.42 percent lower than
the original ore. This proved that the decarburization effect
was achieved by primary oxygen roasting. The content of
Table 4. EDS analysis of carbonaceous shale and roasted product (mass, %)
Elements Position 1 Position 2 Position 3 Position 4 Position 5 Position 6
Na 0.02 0.01 0.01 0.09 0.06 0.06
C 25.76 5.34 3.37 2.27 2.88 1.44
O 11.31 45.08 45.26 47.43 46.25 46.41
Mg 2.72 1.37 0.44 3.30 2.21 3.07
Al 9.62 4.94 1.36 4.14 2.33 5.36
Si 35.49 41.57 46.71 40.44 44.57 41.57
S 1.14 0.11 0.06 0.07 0.02 0.03
K 7.41 0.39 0.74 0.32 0.12 0.18
V 0.67 0.96 1.60 1.04 0.86 0.82
Fe 0.74 0.15 0.38 0.61 0.19 0.64
Ca 0.13 0.10 0.07 0.37 0.51 0.44
2022a). In addition, the weak absorption bands of 797
cm–1, 778 cm–1, and 694 cm–1 also belong to this vibration
(Yuan et al., 2019). The two deeply split bands at 510 cm–1
and 462 cm–1 belonged to Si-O bending vibration (Yuan
et al., 2015). The infrared spectra of high-temperature
reoxidation roasted products at different O2 contents have
significant differences. When the content of O2 increased
to 21%, the hydroxyl vibrational band obviously migrated
from 3442.02 cm–1 to 3421.92 cm–1. This indicated that
the hydroxyl structure in the structural water has changed.
When the content of O2 further increased to 35%, the
hydroxyl vibration band further migrates to 3410.49 cm–1.
At this time, the hydroxyl change in the sample was more
obvious. The change of hydroxyl structure was related to
the lattice damage of vanadium-bearing minerals (Bai et al.,
2022b Li et al., 2023). This showed that the lattice struc-
ture of vanadium-bearing minerals was gradually destroyed
with the increase in oxygen content. Because oxygen was
the reactant of the dehydroxylation process. This conclu-
sion is consistent with the trend of the oxygen condition
experiment. The analysis shows that increasing oxygen
content can promote the lattice damage effect of calcined
products.
Micromorphology of Carbonaceous Shale Surface
SEM analysis of carbonaceous shale raw ore, primary
oxidation roasting products, and high-temperature reoxi-
dation roasting products is shown in Figure 8. EDS spec-
trum analysis is also carried out synchronously, as shown
in Figure 8 and Table 4. Figure 8(a-b) shows the effect of
primary oxygen roasting on the morphology of carbona-
ceous shale. Figure 8(a) shows that the carbonaceous shale
particles were layered. The particle surface was smooth and
compact without holes. However, after roasting at 650 °C
for 0.5 h, the surface of the roasted product became uneven.
A large number of irregular cracks and holes appeared on
the surface of the particles, and the whole particle pre-
sented a loose and porous structure. Because the carbon
that was originally closely embedded with other minerals
was removed by primary oxidation roasting. It was valuable
because the porous structure was more conducive to gas-
solid and liquid-solid reactions. This showed the necessity
of primary oxidation roasting.
The morphology of the roasted products at 700 °C,
850 °C, and 1050 °C were shown in Figure 8(c-e). The
morphology and structure of particles in Figure 8(c) and
Figure 8(d) were similar to those in Figure 8(b). Both pre-
sented a honeycomb porous structure. Because carbon oxi-
dation played a decisive role in morphology. The carbon
in the primary oxidation roasting product was completely
removed, so the high-temperature roasting would not sig-
nificantly change the particle morphology unless sinter-
ing occurred. Figure 8(e) shows that a smooth and dense
“thin film” appeared on the surface of the roasted product
at 1050 °C, resulting in sintering (Yuan et al., 2020b Zhao
et al., 2018). Melting and adhesion occurred on the surface
of the particles, and a large number of holes were covered
by liquid molten substances. On the one hand, this molten
material contained vanadium, on the other hand, it sealed
the pores of particles, and the leaching of V2O5 was greatly
hindered. This sintering phenomenon confirmed the rea-
son why the temperature experiment results at 1050 °C
were poor.
The energy spectrum data in Figure 8 and Table 4
shows the element composition and proportion of each
sample. According to the data in Table 4, elements such
as Si, Al, O, C, Mg, V, S, and Fe are mainly contained in
position 1, indicating that this area contains quartz, mica,
carbonaceous, and pyrite. The mass fraction of element C
in position 2 decreased to 5.34%, 20.42 percent lower than
the original ore. This proved that the decarburization effect
was achieved by primary oxygen roasting. The content of
Table 4. EDS analysis of carbonaceous shale and roasted product (mass, %)
Elements Position 1 Position 2 Position 3 Position 4 Position 5 Position 6
Na 0.02 0.01 0.01 0.09 0.06 0.06
C 25.76 5.34 3.37 2.27 2.88 1.44
O 11.31 45.08 45.26 47.43 46.25 46.41
Mg 2.72 1.37 0.44 3.30 2.21 3.07
Al 9.62 4.94 1.36 4.14 2.33 5.36
Si 35.49 41.57 46.71 40.44 44.57 41.57
S 1.14 0.11 0.06 0.07 0.02 0.03
K 7.41 0.39 0.74 0.32 0.12 0.18
V 0.67 0.96 1.60 1.04 0.86 0.82
Fe 0.74 0.15 0.38 0.61 0.19 0.64
Ca 0.13 0.10 0.07 0.37 0.51 0.44