XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3533
treatment. The process utilizes hydrochloric acid,
sulfuric acid, and oxalic acid as chemical additives
and is widely available on an industrial scale. The
process resulted in the recovery of major elements
of bauxite residue in the form of magnetite (99%
purity, 90% recovery), alumina (98% purity, 31%
recovery) and titanium dioxide (98% purity, 87%
recovery). A liquid stream containing dissolved Sc
is generated for downstream recovery using solvent
extraction to recover critical elements.
• The hydrometallurgical process provides better selec-
tivity and purity of the final products and consumes
less energy than the smelting process. The large-
scale application further depends on factors such as
demand for the recovered products, processing cost
and energy requirement.
• The preliminary technical assessment indicates that
the smelting-based process is energy-intensive, result-
ing in increased processing costs and the generation
of a significant quantity of slag as a by-product. In
contrast, the hydrometallurgical process generates
acid waste streams, which must be either recycled in
the process or discarded after treatment.
REFERENCES
Agrawal, S., V. Rayapudi and N. Dhawan (2019).
“Comparison of microwave and conventional carboth-
ermal reduction of red mud for recovery of iron val-
ues.” Minerals Engineering 132: 202–210.
Borra, C.R., B. Blanpain, Y. Pontikes, K. Binnemans and
T. Van Gerven (2015). “Smelting of Bauxite Residue
(Red Mud) in View of Iron and Selective Rare Earths
Recovery.” Journal of Sustainable Metallurgy 2(1):
28–37.
Cardenia, C., E. Balomenos and D. Panias (2018). “Iron
Recovery from Bauxite Residue Through Reductive
Roasting and Wet Magnetic Separation.” Journal of
Sustainable Metallurgy 5(1): 9–19.
Di Carlo, E., A. Boullemant and R. Courtney (2020).
“Ecotoxicological risk assessment of revegetated baux-
ite residue: Implications for future rehabilitation pro-
grammes.” Sci Total Environ 698: 134344.
Ekstroem, K.E., A.V. Bugten, C. van der Eijk, A. Lazou, E.
Balomenos and G. Tranell (2021). “Recovery of Iron
and Aluminum from Bauxite Residue by Carbothermic
Reduction and Slag Leaching.” Journal of Sustainable
Metallurgy 7(3): 1314–1326.
Grzmil, B.U., D. Grela and B. Kic (2008). “Hydrolysis of
titanium sulphate compounds.” Chemical Papers 62(1):
18–25.
Habashi, F. (2016). A Hundred Years of the Bayer Process
for Alumina Production. Essential Readings in Light
Metals: 85–93.
Hammond, K., B. Mishra, D. Apelian and B. Blanpain
(2013). “CR3 Communication: Red Mud – A Resource
or a Waste?” Jom 65(3): 340–341.
Healy, S. (2022). Sustainable Bauxite Residue Management
Guidance. S. Healy, International Aluminum Institute:
92.
Table 2. Comparison of hydrometallurgical and smelting based processes presented in this work
Smelting Route Hydrometallurgical Route
Major product recovered
(economic values)
Pig iron ($100/MT) High purity (99%) magnetite ($2000/MT)
Titanium dioxide ($3000/MT)
Alumina ($1500/MT)
Scandium oxide ($550000/MT)
Reagents required Lime, Carbon (reductant) Hydrochloric acid, oxalic acid, sulfuric acid
Energy consumption High – Economics highly dependent on
cost of electricity
Low
Drawbacks High energy consumption and capital
investment
Difficulty with slag processing
Carbon emission
Reagent availability and cost
Acid waste management and scaleup
Advantages Potential for processing high volume of
material for pig iron production.
High purity product recovery
Recovery of critical elements such as scandium
treatment. The process utilizes hydrochloric acid,
sulfuric acid, and oxalic acid as chemical additives
and is widely available on an industrial scale. The
process resulted in the recovery of major elements
of bauxite residue in the form of magnetite (99%
purity, 90% recovery), alumina (98% purity, 31%
recovery) and titanium dioxide (98% purity, 87%
recovery). A liquid stream containing dissolved Sc
is generated for downstream recovery using solvent
extraction to recover critical elements.
• The hydrometallurgical process provides better selec-
tivity and purity of the final products and consumes
less energy than the smelting process. The large-
scale application further depends on factors such as
demand for the recovered products, processing cost
and energy requirement.
• The preliminary technical assessment indicates that
the smelting-based process is energy-intensive, result-
ing in increased processing costs and the generation
of a significant quantity of slag as a by-product. In
contrast, the hydrometallurgical process generates
acid waste streams, which must be either recycled in
the process or discarded after treatment.
REFERENCES
Agrawal, S., V. Rayapudi and N. Dhawan (2019).
“Comparison of microwave and conventional carboth-
ermal reduction of red mud for recovery of iron val-
ues.” Minerals Engineering 132: 202–210.
Borra, C.R., B. Blanpain, Y. Pontikes, K. Binnemans and
T. Van Gerven (2015). “Smelting of Bauxite Residue
(Red Mud) in View of Iron and Selective Rare Earths
Recovery.” Journal of Sustainable Metallurgy 2(1):
28–37.
Cardenia, C., E. Balomenos and D. Panias (2018). “Iron
Recovery from Bauxite Residue Through Reductive
Roasting and Wet Magnetic Separation.” Journal of
Sustainable Metallurgy 5(1): 9–19.
Di Carlo, E., A. Boullemant and R. Courtney (2020).
“Ecotoxicological risk assessment of revegetated baux-
ite residue: Implications for future rehabilitation pro-
grammes.” Sci Total Environ 698: 134344.
Ekstroem, K.E., A.V. Bugten, C. van der Eijk, A. Lazou, E.
Balomenos and G. Tranell (2021). “Recovery of Iron
and Aluminum from Bauxite Residue by Carbothermic
Reduction and Slag Leaching.” Journal of Sustainable
Metallurgy 7(3): 1314–1326.
Grzmil, B.U., D. Grela and B. Kic (2008). “Hydrolysis of
titanium sulphate compounds.” Chemical Papers 62(1):
18–25.
Habashi, F. (2016). A Hundred Years of the Bayer Process
for Alumina Production. Essential Readings in Light
Metals: 85–93.
Hammond, K., B. Mishra, D. Apelian and B. Blanpain
(2013). “CR3 Communication: Red Mud – A Resource
or a Waste?” Jom 65(3): 340–341.
Healy, S. (2022). Sustainable Bauxite Residue Management
Guidance. S. Healy, International Aluminum Institute:
92.
Table 2. Comparison of hydrometallurgical and smelting based processes presented in this work
Smelting Route Hydrometallurgical Route
Major product recovered
(economic values)
Pig iron ($100/MT) High purity (99%) magnetite ($2000/MT)
Titanium dioxide ($3000/MT)
Alumina ($1500/MT)
Scandium oxide ($550000/MT)
Reagents required Lime, Carbon (reductant) Hydrochloric acid, oxalic acid, sulfuric acid
Energy consumption High – Economics highly dependent on
cost of electricity
Low
Drawbacks High energy consumption and capital
investment
Difficulty with slag processing
Carbon emission
Reagent availability and cost
Acid waste management and scaleup
Advantages Potential for processing high volume of
material for pig iron production.
High purity product recovery
Recovery of critical elements such as scandium