XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1823
was processed using low-intensity magnetic separation
with a magnetic intensity of 85.19 kA/m. Finally, the iron
concentrate and magnetic tailing of the roasted ore were
obtained. The yield and recovery were calculated based on
the equations (1–2). In the final stage, the samples were
characterized via chemical element analysis, XRD, and
VSM.
γ= (α-θ)/(β-θ)×100% (1)
φ =(β/α)·(α-θ)/(β-θ)×100% (2)
where α, β, and θ are the iron grades of the roasted ore,
magnetic concentrates, and tailings, respectively, γ is the
yield, and φ is the iron recovery.
Characterization
The chemical elemental analyses of raw ore were con-
ducted the Fe and FeO were determined using chemical
titration method the SiO2, Al2O3, MgO, CaO, and P were
determined using X-ray fluorescence (XRF) spectrometry
(Primus II, Japan) the S was determined using a LECO
SC-144DR sulfur analyzer. The mineralogical composition
of limonite samples was detected by a polycrystalline X-ray
diffractometer (PW3040, PANalytical B.V., Netherlands).
The polycrystalline X-ray diffractometer was equipped
with a 2.2 kW Cu anode with a long, fine-focus ceramic
X-ray tube for generating Cu Ka radiation. Scanning range
during detection was 5–90°, scanning speed was 12°/min.
The XRD patterns were analyzed using the software Jade
(6.5) The PDF cards of magnetite (#19-0629), maghemite
(#39-1346), and quartz (#46-1045) were used to identify
the mineral phase. Hysteresis loops were collected using a
vibrating sample magnetometer (JDAW-2000D, China) at
room temperature. A sample of 50.00 mg was weighed and
placed in the holder, after which the hysteresis loops were
measured within the magnetic field in a range of –915–915
kA/m. Magnetic parameters of saturation magnetization,
remanent magnetization, and coercivity were obtained
based on the hysteresis loops.
RESULTS AND DISCUSSION
Magnetising Roasting and Cooling Experiments
The Magnetising roasting of limonite ore was conducted,
and the high-temperature roasted ores were cooled in air
and nitrogen atmospheres and water quenching, respec-
tively. The elemental analysis of cooling ores and magnetic
separation index are shown in Figure 2(a-d). In the tradi-
tional water quenching and nitrogen cooling process, the
high-temperature magnetite was protected from oxidation.
Thus, the iron concentrate can be easily recovered by mag-
netic separation. According to Figure 3(a), an iron concen-
trate with a grade of 58.12% and recovery of 92.27% was
obtained in nitrogen cooling. Compared with the nitrogen
cooling process, the high-temperature synthetic magnetite
was directly exposed to the air atmosphere in air cooling.
However, a good magnetic separation index with an iron
grade of 55.94% and 93.39% was achieved. Generally, the
high-temperature magnetite would be oxidized into hema-
tite, which is an antiferromagnetic mineral and affects the
subsequent magnetic recovery. Based on Figure 2(d), the
most synthetic magnetite must be oxidized into maghemite
but not hematite. Maghemite is a ferrimagnetic mineral
and can be easily recovered.
Figure 1. The schematic diagram of the laboratory magnetising roasting and cooling experiments of limonite ore
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XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1823
was processed using low-intensity magnetic separation
with a magnetic intensity of 85.19 kA/m. Finally, the iron
concentrate and magnetic tailing of the roasted ore were
obtained. The yield and recovery were calculated based on
the equations (1–2). In the final stage, the samples were
characterized via chemical element analysis, XRD, and
VSM.
γ= (α-θ)/(β-θ)×100% (1)
φ =(β/α)·(α-θ)/(β-θ)×100% (2)
where α, β, and θ are the iron grades of the roasted ore,
magnetic concentrates, and tailings, respectively, γ is the
yield, and φ is the iron recovery.
Characterization
The chemical elemental analyses of raw ore were con-
ducted the Fe and FeO were determined using chemical
titration method the SiO2, Al2O3, MgO, CaO, and P were
determined using X-ray fluorescence (XRF) spectrometry
(Primus II, Japan) the S was determined using a LECO
SC-144DR sulfur analyzer. The mineralogical composition
of limonite samples was detected by a polycrystalline X-ray
diffractometer (PW3040, PANalytical B.V., Netherlands).
The polycrystalline X-ray diffractometer was equipped
with a 2.2 kW Cu anode with a long, fine-focus ceramic
X-ray tube for generating Cu Ka radiation. Scanning range
during detection was 5–90°, scanning speed was 12°/min.
The XRD patterns were analyzed using the software Jade
(6.5) The PDF cards of magnetite (#19-0629), maghemite
(#39-1346), and quartz (#46-1045) were used to identify
the mineral phase. Hysteresis loops were collected using a
vibrating sample magnetometer (JDAW-2000D, China) at
room temperature. A sample of 50.00 mg was weighed and
placed in the holder, after which the hysteresis loops were
measured within the magnetic field in a range of –915–915
kA/m. Magnetic parameters of saturation magnetization,
remanent magnetization, and coercivity were obtained
based on the hysteresis loops.
RESULTS AND DISCUSSION
Magnetising Roasting and Cooling Experiments
The Magnetising roasting of limonite ore was conducted,
and the high-temperature roasted ores were cooled in air
and nitrogen atmospheres and water quenching, respec-
tively. The elemental analysis of cooling ores and magnetic
separation index are shown in Figure 2(a-d). In the tradi-
tional water quenching and nitrogen cooling process, the
high-temperature magnetite was protected from oxidation.
Thus, the iron concentrate can be easily recovered by mag-
netic separation. According to Figure 3(a), an iron concen-
trate with a grade of 58.12% and recovery of 92.27% was
obtained in nitrogen cooling. Compared with the nitrogen
cooling process, the high-temperature synthetic magnetite
was directly exposed to the air atmosphere in air cooling.
However, a good magnetic separation index with an iron
grade of 55.94% and 93.39% was achieved. Generally, the
high-temperature magnetite would be oxidized into hema-
tite, which is an antiferromagnetic mineral and affects the
subsequent magnetic recovery. Based on Figure 2(d), the
most synthetic magnetite must be oxidized into maghemite
but not hematite. Maghemite is a ferrimagnetic mineral
and can be easily recovered.
Figure 1. The schematic diagram of the laboratory magnetising roasting and cooling experiments of limonite ore

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