2546 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
roasting, N2 was introduced into the system to remove air.
After heating the roasting furnace to the specified tempera-
ture (heating rate 15°C/min), the sample was placed in the
quartz tube. After the specified roasting time, the roasting
was stopped and cooled to room temperature in the N2
atmosphere. Subsequently, the roasted sample was taken
out for subsequent flotation.
The rotation speed of the flotation machine was 1998
r/min. During flotation, 2g of weighed roasted sample was
put into the flotation tank, 35 mL of deionized water was
added, and the slurry was stirred for 2 min and regulated
to the set pH value (about 9.0). The flotation reagents were
then added sequentially to the slurry using a pipette. The
dosage of MIBC was 100 μL. Flotation was performed after
the specified time was reached. After flotation, the concen-
trate and tailings were dried and weighed to calculate the
recovery.
Calculation Methods
Bastnaesite continues to decompose and decarbonize dur-
ing the roasting process. Its decomposition degree can be
characterized by the ratio of the C content in the roasted
product (CP) to the C content of the raw ore (CR), as shown
in Equation (1) (Q. Zhang et al., 2023a).
The Ce oxidation degree of the roasted products is
determined by the ratio of Ce3+ content to the sum of Ce3+
and Ce4+ content, and its calculation method is shown in
Equation (2) (Teterin et al., 1998).
In this study, single mineral flotation experiments were
conducted and recovery is defined as the ratio of concen-
trate mass (mc) to concentrate and tailings mass (mt) as
shown in (3) (Zhong et al., 2015).
Characterization Techniques
The chemical composition was analyzed by titration and
wavelength dispersive X-ray fluorescence spectrometry
(ZSX100e, Rigaku, Japan). XRD analysis was performed
with an X’Pert pro MRD X-ray diffractometer (PANalytical
B.V., the Netherlands) using cobalt-filtered Cu-Kα radia-
tion, wavelength 1.541 Å, operating voltage 40 kV, operat-
ing current 40 kA, operating power 3 kW, and scanning
speed 10°/min. The microstructure was studied using a
SEM-EDS (Thermo Scientific Apreo 2C, USA, Ultim Max,
Oxford Instruments, UK). And the pore structures were
studied by BET (MicroActive ASAP 2460, Version 2.01,
Micromeritics Inc., USA). XPS analysis was performed
using a Thermo Scientific ESCALAB 250Xi equipped with
an Al Kα X-ray source (1486.6 eV) and the results were
analyzed by AVANTAGE 5.97 software.
RESULTS AND DISCUSSION
Reduction Roasting and Flotation
Effect of Roasting Temperature
Figure 3 presents the effect of varying roasting tempera-
tures on the thermal decomposition of bastnaesite and the
REO grade of the roasted product. The roasting time was
6 min. As illustrated in Figure 3(a), bastnaesite exhibited a
limited decomposition degree at a roasting temperature of
550°C. However, when the temperature was increased to
700°C, the decomposition degree of bastnaesite increased
significantly, reaching almost 100%. The REO grade of the
roasted product gradually increased from about 73% to
about 88% due to the removal of CO2. In a reducing atmo-
sphere, the main decomposition product of bastnaesite was
CeOF (Q. Zhang et al., 2023a), in which cerium existed in
Figure 2. Schematic of reduction roasting and froth flotation process
roasting, N2 was introduced into the system to remove air.
After heating the roasting furnace to the specified tempera-
ture (heating rate 15°C/min), the sample was placed in the
quartz tube. After the specified roasting time, the roasting
was stopped and cooled to room temperature in the N2
atmosphere. Subsequently, the roasted sample was taken
out for subsequent flotation.
The rotation speed of the flotation machine was 1998
r/min. During flotation, 2g of weighed roasted sample was
put into the flotation tank, 35 mL of deionized water was
added, and the slurry was stirred for 2 min and regulated
to the set pH value (about 9.0). The flotation reagents were
then added sequentially to the slurry using a pipette. The
dosage of MIBC was 100 μL. Flotation was performed after
the specified time was reached. After flotation, the concen-
trate and tailings were dried and weighed to calculate the
recovery.
Calculation Methods
Bastnaesite continues to decompose and decarbonize dur-
ing the roasting process. Its decomposition degree can be
characterized by the ratio of the C content in the roasted
product (CP) to the C content of the raw ore (CR), as shown
in Equation (1) (Q. Zhang et al., 2023a).
The Ce oxidation degree of the roasted products is
determined by the ratio of Ce3+ content to the sum of Ce3+
and Ce4+ content, and its calculation method is shown in
Equation (2) (Teterin et al., 1998).
In this study, single mineral flotation experiments were
conducted and recovery is defined as the ratio of concen-
trate mass (mc) to concentrate and tailings mass (mt) as
shown in (3) (Zhong et al., 2015).
Characterization Techniques
The chemical composition was analyzed by titration and
wavelength dispersive X-ray fluorescence spectrometry
(ZSX100e, Rigaku, Japan). XRD analysis was performed
with an X’Pert pro MRD X-ray diffractometer (PANalytical
B.V., the Netherlands) using cobalt-filtered Cu-Kα radia-
tion, wavelength 1.541 Å, operating voltage 40 kV, operat-
ing current 40 kA, operating power 3 kW, and scanning
speed 10°/min. The microstructure was studied using a
SEM-EDS (Thermo Scientific Apreo 2C, USA, Ultim Max,
Oxford Instruments, UK). And the pore structures were
studied by BET (MicroActive ASAP 2460, Version 2.01,
Micromeritics Inc., USA). XPS analysis was performed
using a Thermo Scientific ESCALAB 250Xi equipped with
an Al Kα X-ray source (1486.6 eV) and the results were
analyzed by AVANTAGE 5.97 software.
RESULTS AND DISCUSSION
Reduction Roasting and Flotation
Effect of Roasting Temperature
Figure 3 presents the effect of varying roasting tempera-
tures on the thermal decomposition of bastnaesite and the
REO grade of the roasted product. The roasting time was
6 min. As illustrated in Figure 3(a), bastnaesite exhibited a
limited decomposition degree at a roasting temperature of
550°C. However, when the temperature was increased to
700°C, the decomposition degree of bastnaesite increased
significantly, reaching almost 100%. The REO grade of the
roasted product gradually increased from about 73% to
about 88% due to the removal of CO2. In a reducing atmo-
sphere, the main decomposition product of bastnaesite was
CeOF (Q. Zhang et al., 2023a), in which cerium existed in
Figure 2. Schematic of reduction roasting and froth flotation process