XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1697
Acid leaching
Acid leaching
Red mud HCl
H
2 C
2 O
4 Residue
Residue Recovery of Fe, Sc, Ga
61% Fe, 50% Sc, Ga
1 kg 1.2 L
0.75 kg 1.9 kg
0.48 kg
Recovery of Al, Si
45% Al, 51% Si
Microwave baking
Water Leaching
Red mud H
2 SO
4
H2O
Residue
0.2 kg
Baked red mud
Recovery of metals
70% Ti, 84% Sc, 80% Fe, 90% Al
1 kg 0.8 L
1.75 kg 17.5 L
Water leaching
Alkali baking
Acid leaching
Red mud NaOH
H
2 SO
4
H
2 O Baked red mud
Residue
Recovery of metals
83% Fe, 82% Ti, 97% Sc, 64% Ga
Recovery of Al
60% Al
1 kg 0.75 kg
1.5 kg
0.98 kg
Residue
0.10 kg
15 L
0.2 L
Magnetic separation
Reduction
Acid leaching
Red mud Carbon
HCl
Reduced red mud
Non-mag
Recovery of Al
40% Al
Residue
Recovery of Fe
1 kg 0.1 kg
0.85 kg
0.30 kg 0.45 kg 0.3 L
0.15 kg
Reduction
Acid leaching
Red mud Hydrogen
HCl reduced red mud
Recovery of metals
90% Fe, 95% Ga, 54% Sc
Residue
0.30 kg
1 kg 60 L
0.8 kg 0.9 L
(a) (b) (c)
(d) (e)
Figure 1. Quantitative flowsheet for metal recovery from red mud by (a) AL, (b) AB-WL, (c) HR-AL, (d) CR-AL, and (e) AB-
AL process
Table 1. Optimal conditions of the experimental processes
Process Optimal conditions
Multi-stage acid leaching (MS-AL) 1st stage: 1M HCl, 30 °C, 1 h, S/L 1:20
2nd stage: 2M C
2 H
2 O
4 ,90 °C, 2.5 h, S/L 1:10
Mechanical activation–acid leaching (MA-AL) Milling: 2 h PBM, 300 RPM, ball: sample ratio 10:1
Leaching: 0.5M HCl, 30 °C, 1 h, S/L 1:20
Conventional acid baking–water leaching (AB-WL) Baking: 300–350 °C, 1.5 h, 1 mL/g H
2 SO
4 Leaching: 30 °C, 1 h, S/L 1:10
Microwave acid baking–water leaching (MAB-WL) Baking: 600 W, 6 min, 1 mL/g H
2 SO
4 Leaching: 30 °C, 1 h, S/L 1:10
Alkali baking–water leaching–acid leaching process (AB-AL) Baking: 600 °C, 1–1.5 h, 75 wt.% NaOH
Water leaching: 50 °C, 1 h, S/L 1:10
Acid leaching: 2M H2SO4, 2 h, 80 °C, S/L 1:10
Microwave carbothermal reduction–acid leaching (CR-AL) Reduction: 800 W, 20 min, 10% C
Leaching: 0.5 M HCl, 1 h, 50 °C, S/L 1:20
Hydrogen reduction–acid leaching (HR-AL) Reduction: 900 °C, 1 h, 0.5 LPM (pure H2)
Leaching: 2M H2SO4, 80 °C, 2 h, S/L 1:10
Acid leaching
Acid leaching
Red mud HCl
H
2 C
2 O
4 Residue
Residue Recovery of Fe, Sc, Ga
61% Fe, 50% Sc, Ga
1 kg 1.2 L
0.75 kg 1.9 kg
0.48 kg
Recovery of Al, Si
45% Al, 51% Si
Microwave baking
Water Leaching
Red mud H
2 SO
4
H2O
Residue
0.2 kg
Baked red mud
Recovery of metals
70% Ti, 84% Sc, 80% Fe, 90% Al
1 kg 0.8 L
1.75 kg 17.5 L
Water leaching
Alkali baking
Acid leaching
Red mud NaOH
H
2 SO
4
H
2 O Baked red mud
Residue
Recovery of metals
83% Fe, 82% Ti, 97% Sc, 64% Ga
Recovery of Al
60% Al
1 kg 0.75 kg
1.5 kg
0.98 kg
Residue
0.10 kg
15 L
0.2 L
Magnetic separation
Reduction
Acid leaching
Red mud Carbon
HCl
Reduced red mud
Non-mag
Recovery of Al
40% Al
Residue
Recovery of Fe
1 kg 0.1 kg
0.85 kg
0.30 kg 0.45 kg 0.3 L
0.15 kg
Reduction
Acid leaching
Red mud Hydrogen
HCl reduced red mud
Recovery of metals
90% Fe, 95% Ga, 54% Sc
Residue
0.30 kg
1 kg 60 L
0.8 kg 0.9 L
(a) (b) (c)
(d) (e)
Figure 1. Quantitative flowsheet for metal recovery from red mud by (a) AL, (b) AB-WL, (c) HR-AL, (d) CR-AL, and (e) AB-
AL process
Table 1. Optimal conditions of the experimental processes
Process Optimal conditions
Multi-stage acid leaching (MS-AL) 1st stage: 1M HCl, 30 °C, 1 h, S/L 1:20
2nd stage: 2M C
2 H
2 O
4 ,90 °C, 2.5 h, S/L 1:10
Mechanical activation–acid leaching (MA-AL) Milling: 2 h PBM, 300 RPM, ball: sample ratio 10:1
Leaching: 0.5M HCl, 30 °C, 1 h, S/L 1:20
Conventional acid baking–water leaching (AB-WL) Baking: 300–350 °C, 1.5 h, 1 mL/g H
2 SO
4 Leaching: 30 °C, 1 h, S/L 1:10
Microwave acid baking–water leaching (MAB-WL) Baking: 600 W, 6 min, 1 mL/g H
2 SO
4 Leaching: 30 °C, 1 h, S/L 1:10
Alkali baking–water leaching–acid leaching process (AB-AL) Baking: 600 °C, 1–1.5 h, 75 wt.% NaOH
Water leaching: 50 °C, 1 h, S/L 1:10
Acid leaching: 2M H2SO4, 2 h, 80 °C, S/L 1:10
Microwave carbothermal reduction–acid leaching (CR-AL) Reduction: 800 W, 20 min, 10% C
Leaching: 0.5 M HCl, 1 h, 50 °C, S/L 1:20
Hydrogen reduction–acid leaching (HR-AL) Reduction: 900 °C, 1 h, 0.5 LPM (pure H2)
Leaching: 2M H2SO4, 80 °C, 2 h, S/L 1:10