3526
Utilization of Bayer Process Tailings for Recovery of Base Metals
and Critical Elements
Himanshu Tanvar, Brajendra Mishra
Material Science and Engineering, Worcester Polytechnic Institute
ABSTRACT: The management of environmental hazards of bauxite residue require a sophisticated recycling
system for complete utilization and value recovery. Considering the association of multiple elements (Fe, Al,
Si, Ca, Ti, Sc) within bauxite residue, metal extraction is of prime interest for the circular economic assessment
of aluminum industry. This study presents a hydrometallurgy-based process flowsheet for the sustainable
recovery of base metals and critical elements from bauxite residue. Major elements present in bauxite residue
are recovered as materials for industrial application, including high purity magnetite, alumina, titania, silica,
and calcium carbonate. Critical elements are recovered in the liquid stream generated after the recovery of base
metals. The proposed process is environmentally sound with near-zero waste discharge and presents an excellent
opportunity for comprehensive utilization of bauxite residue.
INTRODUCTION
The Bayer process is a hydrometallurgical process that
involves the dissolution of bauxite ore in a sodium hydrox-
ide solution in an autoclave, followed by precipitation and
calcination to produce alumina (Habashi, 2016). In the
Bayer process, the undissolved fraction of bauxite ore is col-
lected as a residual cake known as bauxite residue or red
mud. The quantity of bauxite residue generated from the
process depends on the production capacity of the individ-
ual alumina refinery, bauxite ore grade, nature of ore and
processing conditions. Production of one ton of alumina
generates 0.7 to 2 tons of bauxite residue, and the annual
waste generation is over 160 million tons, with a total of
4–5 billion tons accumulated by 2023 globally (Evans
2016, Healy 2022). Figure 1 shows the historical data on
the annual bauxite mining, alumina (Al2O3) production
and corresponding residue generation. The global stockpile
of bauxite residue is expected to reach approximately 9–10
billion tons by 2050 if there are no technical advancements
in the processing of bauxite residue (Healy, 2022). Residue
management technology needs to be robust and adaptable
to specific and local circumstances. The recycling practice
used at each refinery will depend on local, geographic,
and environmental conditions and government policies,
regulations, and community factors. High alkalinity and
salinity are the main chemical limitations to plant growth
and rehabilitation of bauxite residue storage lands, which
leaves storage areas unvegetated and can cause environmen-
tal problems (Di Carlo et al., 2020). The accumulation of
bauxite residue in storage facilities presents a significant
challenge for the aluminum industry and has led to a global
effort to find alternative uses for this waste.
Bauxite residue can be utilized itself or can be repur-
posed for recovery of various metallic values through recy-
cling. Historically, bauxite residue has found application
in sectors such as low-volume road construction, filler
production, cement manufacturing, and landfill capping
(Tsakiridis et al., 2004). Recent research has explored
Utilization of Bayer Process Tailings for Recovery of Base Metals
and Critical Elements
Himanshu Tanvar, Brajendra Mishra
Material Science and Engineering, Worcester Polytechnic Institute
ABSTRACT: The management of environmental hazards of bauxite residue require a sophisticated recycling
system for complete utilization and value recovery. Considering the association of multiple elements (Fe, Al,
Si, Ca, Ti, Sc) within bauxite residue, metal extraction is of prime interest for the circular economic assessment
of aluminum industry. This study presents a hydrometallurgy-based process flowsheet for the sustainable
recovery of base metals and critical elements from bauxite residue. Major elements present in bauxite residue
are recovered as materials for industrial application, including high purity magnetite, alumina, titania, silica,
and calcium carbonate. Critical elements are recovered in the liquid stream generated after the recovery of base
metals. The proposed process is environmentally sound with near-zero waste discharge and presents an excellent
opportunity for comprehensive utilization of bauxite residue.
INTRODUCTION
The Bayer process is a hydrometallurgical process that
involves the dissolution of bauxite ore in a sodium hydrox-
ide solution in an autoclave, followed by precipitation and
calcination to produce alumina (Habashi, 2016). In the
Bayer process, the undissolved fraction of bauxite ore is col-
lected as a residual cake known as bauxite residue or red
mud. The quantity of bauxite residue generated from the
process depends on the production capacity of the individ-
ual alumina refinery, bauxite ore grade, nature of ore and
processing conditions. Production of one ton of alumina
generates 0.7 to 2 tons of bauxite residue, and the annual
waste generation is over 160 million tons, with a total of
4–5 billion tons accumulated by 2023 globally (Evans
2016, Healy 2022). Figure 1 shows the historical data on
the annual bauxite mining, alumina (Al2O3) production
and corresponding residue generation. The global stockpile
of bauxite residue is expected to reach approximately 9–10
billion tons by 2050 if there are no technical advancements
in the processing of bauxite residue (Healy, 2022). Residue
management technology needs to be robust and adaptable
to specific and local circumstances. The recycling practice
used at each refinery will depend on local, geographic,
and environmental conditions and government policies,
regulations, and community factors. High alkalinity and
salinity are the main chemical limitations to plant growth
and rehabilitation of bauxite residue storage lands, which
leaves storage areas unvegetated and can cause environmen-
tal problems (Di Carlo et al., 2020). The accumulation of
bauxite residue in storage facilities presents a significant
challenge for the aluminum industry and has led to a global
effort to find alternative uses for this waste.
Bauxite residue can be utilized itself or can be repur-
posed for recovery of various metallic values through recy-
cling. Historically, bauxite residue has found application
in sectors such as low-volume road construction, filler
production, cement manufacturing, and landfill capping
(Tsakiridis et al., 2004). Recent research has explored