2548 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
attributed to the increased porosity of the particles owing to
the increased decomposition degree. The increased porosity
facilitated a larger contact area between the roasted particles
and water during the flotation process, allowing water to
penetrate more easily into the interior of the particles (Yang
et al., 2017). Consequently, this enhanced dissolution rate
led to an increase in the concentration of La and Ce ions
within the solution.
Figure 4(b) presents the flotation experiments for dif-
ferent roasted products. As the SHA dosage increased, the
recovery showed a gradual improvement and stabilized in
the range of 85% to 90%. However, an additional concern
arose as the decomposition degree increased, as the SHA
dosage required to achieve satisfactory recovery gradually
increased. When the roasting temperature reaches 650°C,
the dosage of the agent is 250 mg/L to achieve a recovery
of 84.51%. The increased SHA dosage may be due to the
marked increase in particle porosity leading to enhanced
hydrophilicity. It may also be due to the increase in the
concentration of REEs ions in the solution that formed a
coordination compound with SHA and consumed SHA
(Codd, 2008).
Effect of Roasting Time
Figure 5 illustrates the effect of roasting time on the decom-
position of bastnaesite, with a selected temperature of
650°C. The results indicate a gradual increase in the degree
of decomposition with time, reaching approximately
100% decomposition after 8 min. Additionally, the REO
grade exhibited a gradual increase, reaching approximately
85%. The oxidation rate of Ce initially increased and then
decreased.
Figure 6 depicts the initial pH value of the slurry, the
concentration of La and Ce ions and the flotation experi-
ments of roasted products at different roasting times. As
with the temperature conditions, an increase in the roasting
time resulted in a gradual increase in the initial pH values,
ranging from 7.24 at 2 min to 10.69 at 10 min. It should be
noted that excessively high pH values were not conducive
to the flotation of SHA. In addition, the concentration of
La and Ce ions in the solution also exhibited an increase
with prolonged roasting time. According to Figure 6(b), an
increase in roasting time led to a corresponding increase in
the SHA dosage required to achieve a stable recovery. This
observation suggested that bastnaesite did not effectively
respond to flotation under SHA conditions after reduction
roasting. It is therefore imperative to develop novel collec-
tors that were tailored to the unique properties of roasted
products.
XRD Analysis
Figure 7 illustrates the phase transformation of bastnaesite
at various roasting temperatures. Below 650°C, bastnaesite
remained relatively stable and did not undergo decom-
position, existing in its original phase. At 650°C, a new
product phase began to emerge. Thermodynamic analysis
suggested that the primary product should be REOF (Cen
et al., 2017, 2018). However, the XRD pattern from this
study revealed distinct diffraction peaks corresponding to
REF3 and Ce7O12 in the products at 650°C and 700°C.
2 4 6 8 10
0
20
40
60
80
100
Time (min)
Decomposition degree (a)
2 4 6 8 10
0
20
40
60
80
100
Time (min)
REO grade
Ce oxidation degree
50
60
70
80
90
100
(b)
Figure 5. (a) Decomposition degree of bastnaesite, (b) REO grade and Ce oxidation degree of after roasting
Decomposition
degree(%)
Ce
oxidation
degree(%)
REO
g
de
(%)
attributed to the increased porosity of the particles owing to
the increased decomposition degree. The increased porosity
facilitated a larger contact area between the roasted particles
and water during the flotation process, allowing water to
penetrate more easily into the interior of the particles (Yang
et al., 2017). Consequently, this enhanced dissolution rate
led to an increase in the concentration of La and Ce ions
within the solution.
Figure 4(b) presents the flotation experiments for dif-
ferent roasted products. As the SHA dosage increased, the
recovery showed a gradual improvement and stabilized in
the range of 85% to 90%. However, an additional concern
arose as the decomposition degree increased, as the SHA
dosage required to achieve satisfactory recovery gradually
increased. When the roasting temperature reaches 650°C,
the dosage of the agent is 250 mg/L to achieve a recovery
of 84.51%. The increased SHA dosage may be due to the
marked increase in particle porosity leading to enhanced
hydrophilicity. It may also be due to the increase in the
concentration of REEs ions in the solution that formed a
coordination compound with SHA and consumed SHA
(Codd, 2008).
Effect of Roasting Time
Figure 5 illustrates the effect of roasting time on the decom-
position of bastnaesite, with a selected temperature of
650°C. The results indicate a gradual increase in the degree
of decomposition with time, reaching approximately
100% decomposition after 8 min. Additionally, the REO
grade exhibited a gradual increase, reaching approximately
85%. The oxidation rate of Ce initially increased and then
decreased.
Figure 6 depicts the initial pH value of the slurry, the
concentration of La and Ce ions and the flotation experi-
ments of roasted products at different roasting times. As
with the temperature conditions, an increase in the roasting
time resulted in a gradual increase in the initial pH values,
ranging from 7.24 at 2 min to 10.69 at 10 min. It should be
noted that excessively high pH values were not conducive
to the flotation of SHA. In addition, the concentration of
La and Ce ions in the solution also exhibited an increase
with prolonged roasting time. According to Figure 6(b), an
increase in roasting time led to a corresponding increase in
the SHA dosage required to achieve a stable recovery. This
observation suggested that bastnaesite did not effectively
respond to flotation under SHA conditions after reduction
roasting. It is therefore imperative to develop novel collec-
tors that were tailored to the unique properties of roasted
products.
XRD Analysis
Figure 7 illustrates the phase transformation of bastnaesite
at various roasting temperatures. Below 650°C, bastnaesite
remained relatively stable and did not undergo decom-
position, existing in its original phase. At 650°C, a new
product phase began to emerge. Thermodynamic analysis
suggested that the primary product should be REOF (Cen
et al., 2017, 2018). However, the XRD pattern from this
study revealed distinct diffraction peaks corresponding to
REF3 and Ce7O12 in the products at 650°C and 700°C.
2 4 6 8 10
0
20
40
60
80
100
Time (min)
Decomposition degree (a)
2 4 6 8 10
0
20
40
60
80
100
Time (min)
REO grade
Ce oxidation degree
50
60
70
80
90
100
(b)
Figure 5. (a) Decomposition degree of bastnaesite, (b) REO grade and Ce oxidation degree of after roasting
Decomposition
degree(%)
Ce
oxidation
degree(%)
REO
g
de
(%)