XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1811
additive roasting have also been exposed. Including serious
gas pollution, water pollution, a large amount of reagent
consumption, and high production costs (Dong et al.,
2020).
Non-additive oxidation roasting has been applied and
studied because it does not produce highly polluting waste
gas and wastewater (Xiang et al., 2018). The researchers
carried out experiment on roasting conditions (Cai et al.,
2013 Yuan et al., 2017 Zhou et al., 2023), leaching condi-
tions (Tang et al., 2022), and roasting methods (Dong et
al., 2019 Yuan et al., 2019). However, this technology is
limited by the roasting furnace. The commonly used indus-
trial equipment for carbonaceous shale roasting includes a
shaft furnace, and rotary kiln. And most of the laboratory
research is carried out by muffle furnace (Zeng et al., 2015).
The fluidized roasting technology was proposed, which is
a roasting technology that makes particles and gases form
a fluid state (Yuan et al., 2020a). It strengthens the heat
transfer between gas and particles. It solves the problems
of efficient mixing, heat transfer, mass transfer of materi-
als, and high-temperature airflow (Zhou et al., 2022). In
addition, it is difficult to distinguish the material decom-
position process and the lattice damage process through
only one step of roasting (Bai et al., 2022b). The different
suitable conditions for the two sections of roasting are also
ignored. Therefore, this paper proposes a cascade suspen-
sion roasting process to strengthen acid leaching.
In this paper, a novel process of the cascade suspen-
sion roasting-acid leaching was proposed based on fluid-
ized roasting. It realizes the gradient oxidation of low-valent
vanadium in carbonaceous shale through low-temperature
primary oxidation and high-temperature reoxidation. The
condition experiment of particle size and two roasting sec-
tions were carried out. The optimum conditions of two-
stage roasting were obtained. In addition, XRD, FTIR, and
SEM-EDS were used for analyses of roasted products. The
phase transformation, micro-morphology, and pore struc-
ture changes of minerals during the roasting were observed
and analyzed. The study hopes to provide an efficient and
environmentally friendly process for vanadium purification
of carbonaceous shale.
MATERIALS AND METHODS
Materials
The chemical multi-element analysis of carbonaceous shale
is shown in Table 1. The main component of the carbona-
ceous shale is 66.25% of SiO2. C content is 9.31%, CaO
content is 3.66%, and Al2O3 content is 2.96%. And V2O5
is 0.84% in carbonaceous shale. The content of V(III) must
be 0.44% which accounts for 93.62% of the total vana-
dium content. It shows that vanadium mostly existed in
the form of V(III).
Figure 1 shows the XRD analysis of carbonaceous
shale. It mainly contains quartz, mica, dolomite, barite,
and pyrite. Further process mineralogy analysis shows that
the main components of the ore are quartz, carbonaceous,
mica, plagioclase, barite, dolomite, calcite, pyrite, and limo-
nite. This is consistent with the results of the XRD analysis.
In addition, various minerals and carbonaceous matter are
closely coexisting in carbonaceous siliceous slate. In addi-
tion, vanadium in ore mainly exists in mica, and there is no
independent mineral of vanadium.
Methods and equipment
The flow roaster (OTF-1200X-S-VT, China) was raised to
the experimental temperature at a speed of 15 °C/min. 25 g
Figure 1. XRD analysis of carbonaceous shale
Table 1. Chemical composition analysis of carbonaceous shale
Composition SiO
2 Al
2 O
3 V
2 O
5 V(III) K
2 O MgO TFe
Content /%66.25 2.96 0.84 0.44 1.02 2.42 1.67
Composition C CaO BaO S P Water Ignition loss
Content /%9.31 3.66 2.62 2.72 0.15 0.82 15.21
additive roasting have also been exposed. Including serious
gas pollution, water pollution, a large amount of reagent
consumption, and high production costs (Dong et al.,
2020).
Non-additive oxidation roasting has been applied and
studied because it does not produce highly polluting waste
gas and wastewater (Xiang et al., 2018). The researchers
carried out experiment on roasting conditions (Cai et al.,
2013 Yuan et al., 2017 Zhou et al., 2023), leaching condi-
tions (Tang et al., 2022), and roasting methods (Dong et
al., 2019 Yuan et al., 2019). However, this technology is
limited by the roasting furnace. The commonly used indus-
trial equipment for carbonaceous shale roasting includes a
shaft furnace, and rotary kiln. And most of the laboratory
research is carried out by muffle furnace (Zeng et al., 2015).
The fluidized roasting technology was proposed, which is
a roasting technology that makes particles and gases form
a fluid state (Yuan et al., 2020a). It strengthens the heat
transfer between gas and particles. It solves the problems
of efficient mixing, heat transfer, mass transfer of materi-
als, and high-temperature airflow (Zhou et al., 2022). In
addition, it is difficult to distinguish the material decom-
position process and the lattice damage process through
only one step of roasting (Bai et al., 2022b). The different
suitable conditions for the two sections of roasting are also
ignored. Therefore, this paper proposes a cascade suspen-
sion roasting process to strengthen acid leaching.
In this paper, a novel process of the cascade suspen-
sion roasting-acid leaching was proposed based on fluid-
ized roasting. It realizes the gradient oxidation of low-valent
vanadium in carbonaceous shale through low-temperature
primary oxidation and high-temperature reoxidation. The
condition experiment of particle size and two roasting sec-
tions were carried out. The optimum conditions of two-
stage roasting were obtained. In addition, XRD, FTIR, and
SEM-EDS were used for analyses of roasted products. The
phase transformation, micro-morphology, and pore struc-
ture changes of minerals during the roasting were observed
and analyzed. The study hopes to provide an efficient and
environmentally friendly process for vanadium purification
of carbonaceous shale.
MATERIALS AND METHODS
Materials
The chemical multi-element analysis of carbonaceous shale
is shown in Table 1. The main component of the carbona-
ceous shale is 66.25% of SiO2. C content is 9.31%, CaO
content is 3.66%, and Al2O3 content is 2.96%. And V2O5
is 0.84% in carbonaceous shale. The content of V(III) must
be 0.44% which accounts for 93.62% of the total vana-
dium content. It shows that vanadium mostly existed in
the form of V(III).
Figure 1 shows the XRD analysis of carbonaceous
shale. It mainly contains quartz, mica, dolomite, barite,
and pyrite. Further process mineralogy analysis shows that
the main components of the ore are quartz, carbonaceous,
mica, plagioclase, barite, dolomite, calcite, pyrite, and limo-
nite. This is consistent with the results of the XRD analysis.
In addition, various minerals and carbonaceous matter are
closely coexisting in carbonaceous siliceous slate. In addi-
tion, vanadium in ore mainly exists in mica, and there is no
independent mineral of vanadium.
Methods and equipment
The flow roaster (OTF-1200X-S-VT, China) was raised to
the experimental temperature at a speed of 15 °C/min. 25 g
Figure 1. XRD analysis of carbonaceous shale
Table 1. Chemical composition analysis of carbonaceous shale
Composition SiO
2 Al
2 O
3 V
2 O
5 V(III) K
2 O MgO TFe
Content /%66.25 2.96 0.84 0.44 1.02 2.42 1.67
Composition C CaO BaO S P Water Ignition loss
Content /%9.31 3.66 2.62 2.72 0.15 0.82 15.21