XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2547
a positive trivalent state. However, it was worth noting that
this compound was highly susceptible to oxidation when
exposed to oxygen (Zhao et al., 2018). Consequently, the
Ce oxidation degree increased from 1.72% at 550°C to
66.97% at 700°C. However, at 750°C, the oxidation rate
decreased significantly, which may be due to the increased
crystallinity of the roasted product at this temperature,
making it less susceptible to oxidation.
During the flotation process of the roasted product,
variations in the initial pH values of the slurry were observed
among different samples. These pH values were measured,
together with the main REEs ions (La and Ce) present in
the solution, as depicted in Figure 4(a). As the roasting
temperature increased, corresponding to the decomposi-
tion of bastnaesite, the initial pH value gradually increased
from 7.98 at 550°C to 10.75 at 700°C. This pH increase
could be attributed to the formation of REEs hydroxides
(e.g., Ce(OH)3 and La(OH)3) during the flotation process,
increasing pH value (Hayes et al., 2002 Yu et al., 2006a
Yu et al., 2006b). Furthermore, the concentration of La and
Ce ions in the solution was investigated, revealing a gradual
increase with increasing roasting temperature. This may be
550 600 650 700 750
0
20
40
60
80
100
Temperature (°C)
Decomposition degree (a)
550 600 650 700 750
0
20
40
60
80
100
REO grade
Ce oxidation degree
50
60
70
80
90
100
(b)
Figure 3. (a) Decomposition degree of bastnaesite, (b) REO grade and Ce oxidation degree of after roasting
550 600 650 700 750
6
7
8
9
10
11
12
Temperature (°C)
pH value
La
Ce
0
5
10
15
20
25
(a)
0 50 100 150 200 250 300 350
0
20
40
60
80
100
Raw ore
(b)
Figure 4. (a) initial pH value of slurry and concentration of main rare earth ions in slurry (b) Recovery at different roasting
temperatures with different SHA dosages
Decomposition
degree(%)
Ce
oxidation
degree(%)
REO
g
de
(%)
pH
value Recovery
(%)
a positive trivalent state. However, it was worth noting that
this compound was highly susceptible to oxidation when
exposed to oxygen (Zhao et al., 2018). Consequently, the
Ce oxidation degree increased from 1.72% at 550°C to
66.97% at 700°C. However, at 750°C, the oxidation rate
decreased significantly, which may be due to the increased
crystallinity of the roasted product at this temperature,
making it less susceptible to oxidation.
During the flotation process of the roasted product,
variations in the initial pH values of the slurry were observed
among different samples. These pH values were measured,
together with the main REEs ions (La and Ce) present in
the solution, as depicted in Figure 4(a). As the roasting
temperature increased, corresponding to the decomposi-
tion of bastnaesite, the initial pH value gradually increased
from 7.98 at 550°C to 10.75 at 700°C. This pH increase
could be attributed to the formation of REEs hydroxides
(e.g., Ce(OH)3 and La(OH)3) during the flotation process,
increasing pH value (Hayes et al., 2002 Yu et al., 2006a
Yu et al., 2006b). Furthermore, the concentration of La and
Ce ions in the solution was investigated, revealing a gradual
increase with increasing roasting temperature. This may be
550 600 650 700 750
0
20
40
60
80
100
Temperature (°C)
Decomposition degree (a)
550 600 650 700 750
0
20
40
60
80
100
REO grade
Ce oxidation degree
50
60
70
80
90
100
(b)
Figure 3. (a) Decomposition degree of bastnaesite, (b) REO grade and Ce oxidation degree of after roasting
550 600 650 700 750
6
7
8
9
10
11
12
Temperature (°C)
pH value
La
Ce
0
5
10
15
20
25
(a)
0 50 100 150 200 250 300 350
0
20
40
60
80
100
Raw ore
(b)
Figure 4. (a) initial pH value of slurry and concentration of main rare earth ions in slurry (b) Recovery at different roasting
temperatures with different SHA dosages
Decomposition
degree(%)
Ce
oxidation
degree(%)
REO
g
de
(%)
pH
value Recovery
(%)