1700 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
CONCLUSION
The red mud is evaluated as a polymetallic source for recov-
ering valuable elements such as iron, aluminium, titanium,
scandium, and gallium. The investigated process involves
multi-stage acid leaching, carbothermal and hydrogen
reduction, acid baking–water leaching, and alkali–acid
leaching processes. The comparative analysis of the pro-
cesses indicates that the alkali baking–acid leaching process
is optimal, resulting in maximum metal extraction with
minimal waste generation. The acid–baking–water leaching
process is the least energy-consuming due to lower baking
temperature and water leaching of baked products at room
temperature. The findings indicate that red mud can be
realized as a polymetallic resource. The work demonstrated
may provide the foundation to develop industrial-scale pro-
cesses allowing sustainable and circular resource recovery.
REFERENCES
Agrawal, S., and Dhawan, N. 2023a. Hydrogen Reduction
of Red Mud for Extraction of Metallic Values. Journal
of Sustainable Metallurgy 9(1):386–397.
Agrawal, S., and Dhawan, N. 2023b. Investigation of a novel
alkali baking–leaching process for dissolution of Fe, Al,
Ti, Sc, and Ga values and generation of alumina and
titania from red mud. Hydrometallurgy 218:106057.
Agrawal, S., and Dhawan, N. 2020. Investigation of
carbothermic microwave reduction followed by acid
leaching for recovery of iron and aluminum values from
Indian red mud. Minerals Engineering 159:106653.
Agrawal, S., and Dhawan, N. 2021a. Evaluation of red
mud as a polymetallic source–A review. Minerals
Engineering, 171:107084.
Agrawal, S., and Dhawan, N. 2021b. Investigation of
mechanical and thermal activation on metal extraction
from red mud. Sustainable Materials and Technology
27:e00246.
Table 2 Cost estimations of the processes
Process MS-AL AB-WL AB-AL CR-AL HR-AL
Input
Component
Value
(kg or L/kg)/
($/kg RM)
Value
(kg or L/kg)/
($/kg RM)
Value
(kg or L/kg)/
($/kg RM)
Value
(kg or L/kg)/
($/kg RM)
Value
(kg or L/kg)/
($/kg RM)
Red mud 1 kg 1 kg 1 kg 1 kg 1 kg
H
2 SO
4 /HCl/ C
2 H
2 O
4 1.64 L/1.35kg 1 L 0.8 L 0.74 L 0.9 L
0.868 $0.250 $0.200 $0.148 $0.225 $
NaOH/ Charcoal ----0.75 kg 0.10 kg --
----0.150 $0.050 $--
Processed water 25.9 L 20 L 19.5 L 8.26 L 7.1 L
0.026 $0.020 $0.019 $0.009 $0.007 $
Energy expenditure 5.42 MJ 1.10 MJ 3.95 MJ 1.97 MJ 3.54 MJ
0.106 $0.021 $0.077 $0.038 $0.069 $
Total expenditure 1.00 $0.291 $0.446 $0.245 $0.301 $
Output
Element
Value
(kg or L/kg)/
($/kg RM)
Value
(kg or L/kg)/
($/kg RM)
Value
(kg or L/kg)/
($/kg RM)
Value
(kg or L/kg)/
($/kg RM)
Value
(kg or L/kg)/
($/kg RM)
Alumina/ Aluminium 0.09 kg 0.12 kg 0.14 kg 0.07 kg --
0.036 $0.072 $0.063 $0.028 $--
Titania/ concentrate --0.11 kg 0.13 kg --0.35 kg
--0.422 $0.499 $--0.140 $
FeC
2 O
4 /Fe or Fe
2 O
3 concentrate 0.20 kg 0.18 kg 0.20 kg 0.58 kg 0.23 kg
0.420 $0.020 $0.022 $0.116 $0.046 $
Scandium 32´10–6 kg 53´10–6 kg 57´10–6 kg --32´10–6 kg
0.125 $0.207 $0.222 $--0.125 $
Gallium 33´10–6 kg 65´10–6 kg 54´10–6 kg --80´10–6 kg
0.013 $0.026 $0.021 $--0.032 $
Total value 0.594 $0.747 $0.827 $0.144 $0.343 $
CONCLUSION
The red mud is evaluated as a polymetallic source for recov-
ering valuable elements such as iron, aluminium, titanium,
scandium, and gallium. The investigated process involves
multi-stage acid leaching, carbothermal and hydrogen
reduction, acid baking–water leaching, and alkali–acid
leaching processes. The comparative analysis of the pro-
cesses indicates that the alkali baking–acid leaching process
is optimal, resulting in maximum metal extraction with
minimal waste generation. The acid–baking–water leaching
process is the least energy-consuming due to lower baking
temperature and water leaching of baked products at room
temperature. The findings indicate that red mud can be
realized as a polymetallic resource. The work demonstrated
may provide the foundation to develop industrial-scale pro-
cesses allowing sustainable and circular resource recovery.
REFERENCES
Agrawal, S., and Dhawan, N. 2023a. Hydrogen Reduction
of Red Mud for Extraction of Metallic Values. Journal
of Sustainable Metallurgy 9(1):386–397.
Agrawal, S., and Dhawan, N. 2023b. Investigation of a novel
alkali baking–leaching process for dissolution of Fe, Al,
Ti, Sc, and Ga values and generation of alumina and
titania from red mud. Hydrometallurgy 218:106057.
Agrawal, S., and Dhawan, N. 2020. Investigation of
carbothermic microwave reduction followed by acid
leaching for recovery of iron and aluminum values from
Indian red mud. Minerals Engineering 159:106653.
Agrawal, S., and Dhawan, N. 2021a. Evaluation of red
mud as a polymetallic source–A review. Minerals
Engineering, 171:107084.
Agrawal, S., and Dhawan, N. 2021b. Investigation of
mechanical and thermal activation on metal extraction
from red mud. Sustainable Materials and Technology
27:e00246.
Table 2 Cost estimations of the processes
Process MS-AL AB-WL AB-AL CR-AL HR-AL
Input
Component
Value
(kg or L/kg)/
($/kg RM)
Value
(kg or L/kg)/
($/kg RM)
Value
(kg or L/kg)/
($/kg RM)
Value
(kg or L/kg)/
($/kg RM)
Value
(kg or L/kg)/
($/kg RM)
Red mud 1 kg 1 kg 1 kg 1 kg 1 kg
H
2 SO
4 /HCl/ C
2 H
2 O
4 1.64 L/1.35kg 1 L 0.8 L 0.74 L 0.9 L
0.868 $0.250 $0.200 $0.148 $0.225 $
NaOH/ Charcoal ----0.75 kg 0.10 kg --
----0.150 $0.050 $--
Processed water 25.9 L 20 L 19.5 L 8.26 L 7.1 L
0.026 $0.020 $0.019 $0.009 $0.007 $
Energy expenditure 5.42 MJ 1.10 MJ 3.95 MJ 1.97 MJ 3.54 MJ
0.106 $0.021 $0.077 $0.038 $0.069 $
Total expenditure 1.00 $0.291 $0.446 $0.245 $0.301 $
Output
Element
Value
(kg or L/kg)/
($/kg RM)
Value
(kg or L/kg)/
($/kg RM)
Value
(kg or L/kg)/
($/kg RM)
Value
(kg or L/kg)/
($/kg RM)
Value
(kg or L/kg)/
($/kg RM)
Alumina/ Aluminium 0.09 kg 0.12 kg 0.14 kg 0.07 kg --
0.036 $0.072 $0.063 $0.028 $--
Titania/ concentrate --0.11 kg 0.13 kg --0.35 kg
--0.422 $0.499 $--0.140 $
FeC
2 O
4 /Fe or Fe
2 O
3 concentrate 0.20 kg 0.18 kg 0.20 kg 0.58 kg 0.23 kg
0.420 $0.020 $0.022 $0.116 $0.046 $
Scandium 32´10–6 kg 53´10–6 kg 57´10–6 kg --32´10–6 kg
0.125 $0.207 $0.222 $--0.125 $
Gallium 33´10–6 kg 65´10–6 kg 54´10–6 kg --80´10–6 kg
0.013 $0.026 $0.021 $--0.032 $
Total value 0.594 $0.747 $0.827 $0.144 $0.343 $