Red Mud resources for metal: Comparison
Please note this is a comparison between Version 1 by Sneha Samal and Version 3 by Bruce Ren.

Various scopes are suggested for the utilization of red mud to maintain a sustainable environment. The potential use of red mud covers the valuable metal recovery that could emphasize the use of red mud as a resource. Red mud could act as reduced slag in the metallurgical field for the extraction of minerals and metals for upscale application. Although many studies have revealed the potential utilization of red mud, most of them are only limited to a lab-scale basis. 

  • red mud
  • resources
  • reduced slag
  • metal ion recovery
  • mineralogical

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1. Introduction

Red mud is one of the by-products generated in the aluminum industry from the ore of bauxite during the calcination process for the extraction of aluminum dioxide. The term “red mud” is established and derived from the two words of “red”, which refers to the color, and “mud”, which refers to the waste generated after the alumina extraction from the bauxite ore, by a calcination process. Generally, 2.5–3 kg of red mud is produced in each 1 kg of Al production from the bauxite industry [1]. As the global production of aluminum is approximately 64 million tons, this result in 160 million tons of red mud to dispose of. The current method of red mud disposal is to simply pump it into ponds or dry up the red mud with a special liner [12]. In both approaches, a large amount of land is used and ultimately the land should be maintained properly, rather than disposing of the product as waste to the surrounding area, causing serious environmental issues and health hazards. The alkaline nature of red mud and dried-up dust disposable to the environment could be minimized by spraying water on the dry red mud powders. Furthermore, the alkaline nature of red mud inhibits the vegetation growth in those areas, thus it must be corrected by adding acidic flux before its disposal into the surroundings. Given all these environmental implications, it would be appropriate to think of a new use for red mud. “Waste is a resource if we use it. Otherwise, it is waste if we waste it” [13]. Thus, the red mud residue, after the extraction of the minerals, could be considered as a potential building material for the construction of roads, landfill sites, and building materials. Recently, a combination of red mud–fly ash composite could find application in the preparation of geopolymers as an alternative material for the construction industry [4][25].
The recovery of critical raw materials from red mud involves many benefits including environmental, social, financial, economic, and technological benefits [26][37]. The content of metals such as Ti, Si, Fe, Na, and Al in red mud is 2–12%, 1–9%, 14–45%, 1–6% and 5–14% respectively. Apart from representing a huge solution in the construction sector, when present in a large quantity, red mud as a resource opens up various possibilities for the extraction of minerals and ions such as the major elements Fe, Ti, Mn, Al and Ca, Na, Si, Cr, Mn, V, La, Sc, Y. Rare earth elements (REE) such as Ce (102 mg/kg), La (56 mg/kg), Sc (47 mg/kg), Nd (45 mg/kg), Sm (9 mg/kg) are also valuable elements present inside red mud. REE are the most important critical raw materials for the European Union [48]. Red mud can be also considered as sintered ceramics for electroceramic materials [59][610][711].
In powder technology, red mud could be considered as resource for the recovery of metals such as Fe, Ti, Mn, Na, K [812][913]. Simultaneously, red mud could be used as a coating material for various composites against harsh environments and high-temperature sintering, against wear and corrosive behavior [1014][1115][1216]. Unlike the recovery of metal ions, which will certainly not be the main business for the red mud, it could also act as the main component for construction and road fill materials [1317][1418]. Fly ash with acidic nature inhibits agglomeration of the volatilization of heavy metals at low temperatures within the red mud combination [1519][1620][1721].
In Figure 1 the combination of various technologies that could be implemented for a complete utilization strategy is shown. The comprehensive utilization of red mud as a resource opens up in various sectors such as red mud-based geopolymers in the construction and metal extraction industries. Synergetic utilization of red mud emerges as flue gas in the geopolymer industry sector for an alternative binder in cement material. The exploitation of these potential techniques, for metal extraction from red mud, is subordinate to the establishment of a small plant, near the aluminum industry, for resource utilization [1822][1923][2024][2125]. The reduction of red mud and fly ash mixtures proved the formation of reduced slag in the sintering process during lab-scale experiments. Based on the latter, it is possible to design a synergetic utilization for the red mud/fly ash mixture. It has been seen that the hazardous heavy metals could be recovered as alloy from the reduced slag [2226][2327]. Therefore, this environmentally friendly co-reduction process could be implemented as one sound solution for red mud and fly ash, leading to complete utilization of the resources, thus representing a zero-waste technology [2428]. The optimized parameters for the reduction process were chosen as 20 wt.% fly ash with 80 wt.% red mud, at a temperature of 1100 °C for 2 h. The sintered slag contained CaO, SiO2, Al2O3, and FeO, as well as a glass phase, which is similar to ground-granulated blast-furnace slag and supports broad future applications. It has also been seen that the treatment of the red mud’s alkaline nature with an additive for surface modification will enhance the utilization on an upscale basis [2529][2630]. The major and minor elements of red mud are quantified in Table 1.
Figure 1. Scheme representing the technologies implemented in red mud for its complete utilization in various sectors.
Table 1. Quantification of major elements (wt.%) and minor elements (Conc. Mg/kg) of red mud.
[4145].
Figure 4. The various areas of red mud utilizations.
Foaming ceramics are emerging as a new group of materials that could improve performance that could act as energy-saving materials [4246]. Sintering and thermal plasma open the possibility of the synthesis of energy-saving materials by generating porosity in the sintered material [4347][4448]. In these cases, sintering is one of the effective processes of using carbo-thermal reduction inside the furnace that facilitates the formation of sintered slag. The quantity of fly ash content (wt.%) reduces the mixture of red mud and fly ash that undergoes chemical and physical reduction processes as a function of sintering temperature. The mineralogical evolution in the sintered product and the end-product was examined to confirm the presence of minerals and ions at the end of the process.

2.3. Sources of Metal Ions

In this article, an effort was made to create a review in the area of utilization of red mud as a source of metal ions. Various steps and process related to the mineralogical evolution of various metal and rare earth ions in red mud are covered and discussed. Simultaneously, the application of red mud in various fields is covered, where red mud could be given importance as a resource rather than waste.
Table 2 shows the red mud generated from various plants with different chemical compositions.
Table 2. Major elemental composition of red mud from various locations in the countries.
Composition wt.%
Location Al2O3 Fe2O3 SiO2 TiO2 CaO Na2O Mn P2O5 V2O5 Gd2O3 MgO K2O LOI REFs
Ajka Aluminum Industry, Hungary 16–18 33–48 9–15 4–6 0.5–3.5 8–12 - - 0.2–0.3 - 0.3–1 - - [3135]
Al2O3 10–20 Ga 60–80 [28
Aluminium Pechiney, Gardanne, France32] 15.00[2933]
26.62 4.98 15.76 22.21 1.02 - -- - - 0.95 - 12.10 [3337] SiO2 3–50 V 730 [2832][2933][3034][3135]
Bauxite ore refinery, Guinea 26.60 48.40 5.50 - 1.30 - - - - - 0.90 - 14.60 [3236] Na2O 2–10
ALCOA factory, San Cibrao (Northwest of Spain) 12.00Zr 1230 [3236][3337]
37.00 9.00 20.00 6.00 5.00 - - - - - - - [3539] CaO 2–8 Sc 60–120
Korea Chemical Co. 23.70 16.60[34 22.9038]
6.70 6.70 11.60 - - - - - - - [3640] TiO2 8.50 Cr
Shandong Aluminium Factory, China497 7.96[3438]
6.57 21.90 - 38.84 2.32 - - - - 1.60 0.41 17.42 [3741] P2O5 0.25 Mn
Greek red mud, Greece 15.6085 [3539]
42.50 9.20 5.90 19.70 2.40 - - - - - - - [3842] MgO 0.10 Y
Slurry pond from Worsley Alumina, Australia 15.0060–150 60.00[3539 5.00][3640]
5.00 - 16.00 - - - - - - - [3943] K2O 0.06 Ni 31 [3438]
Alpart factory and the Alcan Ewartonred mud pond, Jamaica 18.80 45.30 4.30 6.40 3.10 1.50 - - - - - -   [4044] Zn 20
Shandong Aluminium Corporation, Shandong, China 6.93 12.76[3438]
La 0.1–1% [3741]
Th 20–30 [3842]
The composition shows the presence of heavy irons and minerals of Fe, Si, and Ti in the major quantity. Red mud could be considered as bricks, road surface material, and in the cement industry with potential use for building applications. However, this approach is limited due to the alkaline nature of the material. The alkaline nature of red mud is reduced by the acidic counterpart of fly ash, generating the neutral nature of the composite. The latter could be the most significant solution for the vastness of the problem, but careful consideration is required for this application. After the Al content, Fe represents the second-largest amount of metal that is separated by a magnetic separator. The nonmagnetic part of the residue can be considered as a construction material. Furthermore, some researchers searched for producing steel and cement from red mud [3943]. Additionally, the recovery of Al, caustic soda, and lime could be used as catalyst for enhancing the Bayer process for increased Al production. However, despite the invaluable outcomes obtained from all techniques associated with red mud utilization, they are not practically suitable to use for recycling large amounts of red mud (currently 160 million tons annually [4044]). The amount or iron in red mud is the largest, which, when disposed with red mud annually, represents a waste of metal [4145]. Thus, metal recovery from red mud opens a wide field for potential utilization as resource.

2. Sources and Utilization of Red Mud

2.1. Relevant Sources for Literature Review

A broad range of literature sources, dating from 1991 to 2021, in the areas of red mud and red mud composites were reviewed for this article. The databases searched for this literature survey include various sources such as MDPI, Scopus, Science Direct, Google Scholar, and Springer. Articles, conference proceedings, data, reviews, chapters, and books of similar topics were filtered using search terms such as “red mud”, “composite”, “mineral”, “microstructure evolution”, “metal ion recovery”, “mineralogical characteristics of the materials”. Section 1 in the introduction includes all the potential previous studies in this area. Section 2 includes various types of red mud and composites with potential applications. The basic and advanced application of red mud and composite is followed in Section 3 with emphasis on some recent literature surveys. Section 4 compares the data with the present scenario through an exhaustive literature survey. Figure 2 displays the total publication from 2010–2021 in the area of red mud that consider it as a source of metal and ions.
Figure 2. Total publications as function of year for red mud considered as source of ions (data collected from Web of Science).

2.2. Utilization of Red Mud as Metal Resource

Although researchers highlight that red mud is a large contributor to the construction sector, it is generally recognized as waste material. The term “waste” creates, both psychologically and from a media viewpoint, an obstacle in the application areas. Thus, replacing the term “waste” with “resource” could add significant interest in the extraction of minerals and their use. In this work, an investigation was carried out for review in the area of utilization of red mud as a source of metallic ions and resource material. Red mud, added with various weight percentages of fly ash to neutralize the acidity, undergoes the sintering process for the conversion into a reduced slag material. This sintered product could act as a basic resource for the extraction of metal ions and as a major by-product for the mineral industry. Figure 3 illustrates the red mud utilization from the as-received stage towards the final stage for industrial utilization.
Figure 3. Schematic flow sheet on the iron, alumina, and slag for recovery of various metals.
The dry red mud undergoes magnetic and non-magnetic separation that follows up the smelting process for iron recovery. Non-magnetic parts undergo the leaching process for Al recovery. Figure 3 portrays the flow sheet of various types of red mud utilization. Preliminary treatment involves the magnetic separations of bulk iron parts from the red mud. Accordingly, the magnetic and non-magnetic parts undergo different treatment in the further steps for iron recovery on the acceptable norms. If the magnetic parts are non-acceptable, they undergo smelting for iron recovery. The non-magnetic parts undergo leaching for alumina recovery and the residue undergoes slag recovery as the utilization of the major parts. A key point to benefit in terms of human resources and the economy could be the establishment of a plant for the beneficiation of red mud as resource alongside the bauxite industry. Particularly, to avoid transportation costs, the waste utilization facility processes and tools such as electric arc furnace, sintering of red mud, and leaching facility should be present in the proximal areas of the aluminum industry. One of the innovative processes in the production of pig iron is a by-product from reduced red mud by the carbothermal reduction process. The various process and active areas in which red mud can be treated can be divided into major and minor activities (Figure 4). Red mud can be used as a primary resource in the construction industry, for example, as bricks and other suitable materials for making houses, or as material for pavement. Red mud could be used in the industrial sector of iron recovery or metal extraction and smelting for the by-product of pig iron and calcium titanium-rich compounds for recovery of titanium. Finally, it can be used in the carbothermal reduction process for iron recovery, which could be a possible step for steel making. The rest of the residual red mud could be considered as the reductant for alumina recovery. Major use in the areas of construction and landfill opens the application of red mud in combination with metal recoveries such as Al, Fe, and its integrated combination towards the reduction process for the steelmaking. Integrating the red mud with other materials could improve its use in synergetic utilization
19.14
3.43
46.02
2.37
-
- - - 1.15 1.20 5.73 [4145]
Alumina-aluminio of San Ciprian, Lugo, Spain 20.10 31.80 6.10 22.60 4.78 4.70 - - - - 0.20 0.03   [4246]
Etibank Seydiehir Aluminium Plant, Konya, Turkey 20.39 36.94 15.74 4.98 2.23 10.10 - - 0.05 - -   8.19 [4347]
Aluminium of Greece S.A. 15.65 45.58 6.96 7.07 14.84 3.26 - - - - - 0.07 - [4448]
Eurallumina alumina plant, Italy 17.19 30.45 9.58 8.61 7.77 12.06 - - - - 0.86 0.30 12.38 [4549]
Queensland Alumina Ltd. refinery, Gladstone, Australia 25.45 34.05 17.06 4.90 3.69 2.74 - - - - 1.86 0.20 - [4650]
Seydiehir Aluminium Plant, Konya, Turkey 14.10 38.30 2.50 - 4.10 - - - - - - -   [4751]
HINDALCO Renukoot, India 21.9 28.1 7.5 15.6 10.2 4.5 - - 12.2 [4852]
IND ALMuri, India 24.3 24.5 6.2 18.0 5.3 - - [4852]
BALCO Kobra, India 19.4 27.9 7.3 16.4 11.8 3.3 - - 12.6 [4852]
NALCo Damanjodi, India 14.8 54.8 6.4 3.7 2.5 4.8 1.1 0.67 0.38 0.01 - - 9.5 [4852]
INDALBelgam, India 19.2 44.5 7.0 13.5 0.8 4.0 -- - 10.0 [4852]
MALCO Mettur Dam, India 14.0 18.0 56.0 50.0 2.0–4.0 6.0–9.0 1.0–2.0 - - 12.60 [4852]

References

  1. Kumar, A.; Kumar, S. Development of paving blocks from synergistic use of red mud and fly ash using geopolymerization. Constr. Build. Mat. 2013, 38, 865.Rai, S.; Bahadure, S.; Chaddha, M.J.; Agnihotri, A. Disposal Practices and Utilization of Red Mud (Bauxite Residue): A Review in Indian Context and Abroad. J. Sustain. Metall. 2020, 6, 1.
  2. Chen, X.; Lu, A.; Qu, G. Preparation and characterization of foam ceramics from red mud and fly ash using sodium silicate as foaming agent. Ceram. Int. 2013, 39, 1923.Menzies, N. Seawater Neutralization of Alkaline Bauxite residue and Implications for revegetation. J. Environ. Qual. 2004, 33, 1877.
  3. Samal, S.; Ray, A.K.; Bandopadhyay, A. Characterization and microstructure observation of sintered red mud–fly ash mixtures at various elevated temperatures. J. Clean. Prod. 2015, 101, 368.Yang, Z.; Mocadlo, R.; Zhao, M.; Sisson, R.D., Jr.; Tao, M.; Liang, J. Preparation of a geopolymer from red mud slurry and class F fly ash and its behavior at elevated temperatures. Constr. Build. Mat. 2019, 221, 308.
  4. Lothenbach, B.; Scrivener, K.; Hooton, R.D. Supplementary cementitious materials. Cem. Concr. Res. 2011, 41, 1244–1256.Samal, S. Effect of high temperature on the microstructural evolution of fiber reinforced geopolymer composite. Heliyon 2019, 5, e01779.
  5. Samal, S. Study of Porosity on Titania Slag Obtained by Conventional Sintering and Thermal Plasma Process. JOM 2016, 68, 3000.Catauro, M.; Tranquillo, E.; Barrino, F.; Dal Poggetto, G.; Blanco, I.; Cicala, G.; Ognibene, G.; Recca, G. Mechanical and thermal properties of fly ash-filled geopolymers. J. Therm. Anal. Calorim. 2019, 138, 3267.
  6. Blanco, I.; Cicala, G.; Tosto, C.; Recca, G.; Dal Poggetto, G.; Catauro, M. Kinetic study of the thermal dehydration of fly ash filled Geopolymers. Macromol. Symp. 2020. accepted.Samal, S.; Ray, A.K.; Bandopadhyay, A. Proposal for resources, utilization and processes of red mud in India—A review. Int. J. Miner. Process. 2013, 118, 43.
  7. Samal, S. High temperature oxidation of Metals. InTech Open 2016, 6, 101–121.Hammond, K.; Mishra, B.; Apelian, D.; Blanpain, B. CR3 communication: Red mud—A resource or a waste? JOM 2013, 65, 340.
  8. Samal, S. Thermal plasma technology: The prospective future in material processing. J. Clean. Prod. 2017, 142, 3131.Tulsidas, H.; Gabriel, S.; Kiegiel, K.; Haneklaus, N. Uranium resources in EU phosphate rock imports. Resour. Policy 2019, 61, 151–155.
  9. Samal, S. Thermal Plasma Processing of Materials: High Temperature Applications; Elsevier: Amsterdam, The Netherlands, 2020.Yao, L.; Gao, W.; Ma, X.; Fu, H. Properties Analysis of Asphalt Binders Containing Bayer Red Mud. Materials 2020, 13, 1122.
  10. Gomez, E.; Amutha Rani, D.; Cheeseman, C.R.; Deegan, D.; Wise, M.; Boccaccini, A.R. Thermal plasma technology for the treatment of wastes: A critical review. J. Hazard. Mat. 2009, 161, 614.Borra, C.R.; Pontikes, Y.; Binnemans, K.T.; Gerven, V. Leaching of rare earths from bauxite residue (red mud). Miner. Eng. 2015, 76, 20–27.
  11. Guo, Y.-H.; Gao, J.-J.; Xu, H.-J.; Zhao, K.; Shi, X.-F. Nuggets production by direct reduction of high Iron red mud. J. Iron Steel Res. Int. 2013, 20, 24–27.Choe, G.; Kang, S.; Kang, H. Mechanical Properties of Concrete Containing Liquefied Red Mud Subjected to Uniaxial Compression Loads. Materials 2020, 13, 854.
  12. Kumar, R.; Srivastava, J.; Premchand, P. Utilization of iron values of red mud for metallurgical applications. Environ. Waste Manag. 1998, 108–119. Available online: (accessed on 10 April 2021).Ortega, J.M.; Cabeza, M.; Tenza-Abril, A.J.; Real-Herraiz, T.; Climent, M.Á.; Sánchez, I. Effects of Red Mud Addition in the Microstructure, Durability and Mechanical Performance of Cement Mortars. Appl. Sci. 2019, 9, 984.
  13. Xiaoming, L.; Na, Z. Utilization of red mud in cement production: A review. Waste Manag. Res. 2011, 29, 1053.Wang, P.; Liu, D.-Y. Physical and Chemical Properties of Sintering Red Mud and Bayer Red Mud and the Implications for Beneficial Utilization. Materials 2012, 5, 1800–1810.
  14. Sglavo, V.M.; Campostrini, R.; Maurina, S.; Carturan, G.; Monagheddu, M.; Budroni, G.; Cocco, G. Bauxite “red mud” in the ceramic industry. Part 1: Thermal behavior. J. Eur. Ceram. Soc. 2000, 20, 235.Choe, G.; Kang, S.; Kang, H. Characterization of Slag Cement Mortar Containing Nonthermally Treated Dried Red Mud. Appl. Sci. 2019, 9, 2510.
  15. Chen, R.; Cai, G.; Dong, X.; Mi, D.; Puppala, A.J.; Duan, W. Mechanical properties and micro mechanism of loess roadbed filling using by product red mud as a partial alternative. Constr. Build. Mater. 2019, 216, 188.Rao, P.P. The characteristics and genesis discussion of fracture in dry red mud disposal yard. Ind. Const. 2010, 40, 73–77.
  16. Alam, S.; Das, S.K.; Rao, B.H. Strength and durability characteristic of alkali activated GGBS stabilized red mud as geo-material. Constr. Build. Mater. 2019, 211, 932.Chen, X.; Guo, Y.; Ding, S.; Zhang, H.; Xia, F.; Wang, J.; Zhou, M. Utilization of red mud in geopolymer-based previous concrete with function of adsorption of heavy metal ions. J. Clean. Prod. 2019, 207, 789.
  17. Samal, S.; Thanh, N.P.; Marvalova, B.; Petrikova, I. Thermal characterization of metakaolin-based geopolymer. JOM 2017, 69, 2480–2484.Ascensao, G.; Seabra, M.P.; Aguiar, B.J. Labrincha. J.A. Red mud-based geopolymers with tailored alkali diffusion properties and pH buffering ability. J. Clean. Prod. 2017, 148, 23.
  18. Jakob, A.; Stucki, S.; Kuhn, P. Evaporation of hevy-metals during the heat treament of municipal solid waste incinerator fly ash. Environ. Sci. Technol. 1995, 29, 2429.Mahinroosta, M.; Karimi, Z.; Allahverdi, A. Recycling of red mud for value-added applications: A comprehensive Review. Encyl. Renew. Sust. Mat. 2020, 2, 561.
  19. Tang, W.C.; Wang, Z.; Liu, Y.; Cui, H.Z. Influence of red mud on fresh and hardened properties of self-compacting concrete. Construct. Build. Mater. 2018, 178, 288.Guo, Y.-H.; Gao, J.-J.; Xu, H.-J.; Zhao, K.; Shi, X.-F. Nuggets production by direct reduction of high Iron red mud. J. Iron Steel Res. Int. 2013, 20, 24–27.
  20. Patel, S.; Pal, B. Current status of industrial waste: Red mud an overview. Int. J. Latest Technol. Eng. Manag. Appl. Sci. 2015, 4, 1–16. Available online: (accessed on 10 April 2021).Kumar, R.; Srivastava, J.; Premchand, P. Utilization of iron values of red mud for metallurgical applications. Environ. Waste Manag. 1998, 108–119. Available online: (accessed on 10 April 2021).
  21. Xue, S.G.; Zhu, F.; Kong, X.F.; Wu, C.; Huang, L.; Huang, N.; Hartley, W. A review of the characterization and revegetation of bauxite residues (Red mud). Environ. Sci. Pollut. Res. 2016, 23, 1120.Kumar, S.; Kumar, R.; Bandopadhyay, A. Innovative methodologies for the utilization of wastes from metallurgical and allied industries. Resour. Conserv. Recycl. 2006, 48, 301–314.
  22. Geng, C.; Liu, J.; Wu, S.; Jia, Y.; Du, B.; Yu, S. Novel method for comprehensive utilization of MSWI fly ash through co-reduction with red mud to prepare crude alloy and cleaned slag. J. Hazard. Mater. 2020, 384, 121315.Jayasankar, K.; Ray, P.K.; Chaubey, A.K.; Padhi, A.; Satapathy, B.K.; Mukherjee, P.S. Production of pig iron from red mud waste fines using thermal plasma technology. Int. J. Miner. Metall. Mater. 2012, 19, 679–684.
  23. Geng, C.; Chen, C.; Shi, X.; Wu, S.; Jia, Y.; Du, B.; Liu, J. Recovery of metals from municipal solid waste incineration fly ash and red mud via a co-reduction process. Resour. Conserv. Recycl. 2020, 154, 104600.Lim, K.; Shon, B. Metal Components (Fe, Al and Ti) recovery from red mud by sulfuric acid leaching assisted with ultrasonic waves. Int. J. Emerg. Technol. Adv. Eng. 2015, 5, 25–32.
  24. Okada, T.; Tomikawa, H. Efficiencies of metal separation and recovery in ash-melting of municipal solid waste under non-oxidative atmospheres with different reducing abilities. J. Environ. Manag. 2016, 166, 147.Voßenkaul, D.; Birich, A.; Müller, N.; Stoltz, N.; Friedrich, B. Hydrometallurgical processing of eudialyte bearing concentrates to recover rare earth elements via low-temperature dry digestion to prevent the silica gel formation. J. Sustain. Metall. 2017, 3, 79–89.
  25. Liu, Y.; Zhao, B.; Tang, Y.; Wan, P.; Chen, Y.; Lv, Z. Recycling of iron from red mud by magnetic separation after co-roasting with pyrite. Thermochim. Acta 2014, 588, 11.Schwarzenbach, G.; Muehlebach, J.; Mueller, K. Peroxo complexes of titanium. Inorg. Chem. 1970, 9, 2381–2390.
  26. Giannopoulou, I.; Dimas, D.; Maragkos, I.; Panias, D. Utilization of metallurgical solid by-products for the development of inorganic polymeric construction materials. Glob. NEST J. 2009, 11, 127–136.Antonijević, M.; Dimitrijević, M.; Janković, Z. Leaching of pyrite with hydrogen peroxide in sulphuric acid. Hydrometallurgy 1997, 46, 71–83.
  27. Geng, C.; Wang, H.; Hu, W.; Li, L.; Shi, C. Recovery of iron and copper from copper tailings by coal-based direct reduction and magnetic separation. J. Iron Steel Res. Int. 2017, 24, 991.Yagmurlu, B.; Dittrich, C.; Friedrich, B. Precipitation Trends of Scandium in Synthetic Red Mud Solutions with Different Precipitation Agents. J. Sustain. Metall. 2017, 3, 90–98.
  28. Hu, H.; Liu, H.; Zhang, Q.; Zhang, P.; Li, A.; Yao, H.; Naruse, I. Sintering characteristics of CaO-rich municipal solid waste incineration fly ash through the addition of Si/Al-rich ash residues. J. Mater. Cycles. Waste 2016, 18, 340.Khairul, M.A.; Zanganeh, J.; Moghtaderi, B. The composition, recycling and utilisation of bayer red mud. Resour. Conserv. Recycl. 2019, 141, 483–498.
  29. Kang, S.; Kang, H.; Lee, B. Effects of Adding Neutralized Red Mud on the Hydration Properties of Cement Paste. Materials 2020, 13, 4107.Sutar, H.; Mishra, S.C.; Sahoo, S.K.; Maharana, H. Progress of red mud utilization: An overview. Am. Chem. Sci. J. 2014, 4, 255–279.
  30. Cardenia, C.; Balomenos, E.; Panias, D. Optimization of Microwave Reductive Roasting Process of Bauxite Residue. Metals 2020, 10, 1083.Rickhov, V.; Botalov, M.; Kirilov, E.; Kirilov, S.; Semenishchev, V.; Bunkov, G.; Smyshlyaev, D. The investigation of sulphuric acid sorption recovery of scandium and uranium from the red mud of alumina production. Hydrometallurgy 1997, 45, 249–259.
  31. Keller, V.; Stopić, S.; Xakalashe, B.; Ma, Y.; Ndlovu, S.; Mwewa, B.; Simate, G.S.; Friedrich, B. Effectiveness of Fly Ash and Red Mud as Strategies for Sustainable Acid Mine Drainage Management. Minerals 2020, 10, 707.Wang, W.; Pranolo, Y.; Cheng, C.Y. Recovery of scandium from synthetic red mud leach solutions by solvent extraction with D2EHPA. Sep. Purif. Technol. 2013, 108, 96–102.
  32. Chaikin, L.; Shoppert, A.; Valeev, D.; Loginova, I.; Napol’skikh, J. Concentration of Rare Earth Elements (Sc, Y, La, Ce, Nd, Sm) in Bauxite Residue (Red Mud) Obtained by Water and Alkali Leaching of Bauxite Sintering Dust. Minerals 2020, 10, 500.Ning, G.; Zhang, B.; Liu, C.; Li, S.; Ye, Y.; Jiang, M. Large-Scale Consumption and Zero-Waste Recycling Method of Red Mud in Steel Making Process. Minerals 2018, 8, 102.
  33. Nie, Q.; Li, Y.; Wang, G.; Bai, B. Physicochemical and Microstructural Properties of Red Muds under Acidic and Alkaline Conditions. Appl. Sci. 2020, 10, 2993.Pascual, J.; Corpas, F.; López-Beceiro, J.; Benítez-Guerrero, M.; Artiaga, R. Thermal characterization of a Spanish red mud. J. Therm. Anal. Calorim. 2009, 96, 407–412.
  34. Vigneshwaran, S.; Uthayakumar, M.; Arumugaprabu, V. Potential use of industrial waste-red mud in developing hybrid composites: A waste management approach. J. Clean. Prod. 2020, 276, 124278.Mauskar, J. Assessement of Utilization of Industrial Solid Waste in Cement Manufacturing; Central Pollution Control board: Delhi, India, 2006.
  35. Singh, S.; Aswath, M.U.; Ranganath, R.V. Performance assessment of bricks and prisms: Red mud based geopolymer composite. J. Build. Eng. 2020, 32, 101462.Pratt, K.C.; Christoverson, V. Hydrogenatation of a model hydrogen-donor system using activated red mud catalyst. Fuel 1982, 61, 460–462.
  36. Liu, D.-Y.; Wu, C.-S. Stockpiling and Comprehensive Utilization of Red Mud Research Progress. Materials 2012, 5, 1232–1246.Halász, J.; Hodos, M.; Hannus, I.; Tasi, G.; Kiricsi, I. Catalytic detoxification of C2-chlorohydrocarbons over iron-containing oxide and zeolite catalysts. Colloids Surf. A 2005, 265, 171–177.
  37. Laskou, M.; Andreou, G. Rare earth elements distribution and REE-minerals from the Parnassos–Ghiona bauxite deposits, Greece. In Proceedings of the 7th Biennial SGA Meeting on Mineral Exploration and Sustainable Development, Athens, Greece, 24–28 August 2003; pp. 89–92.Rivera, R.; Ulenaers, B.; Ounoughene, G.; Binnemans, K.; Gerven, T. Extraction of rare earths from bauxite residue (red mud) by dry digestion followed by water leaching. Miner. Eng. 2018, 119, 82–92.
  38. Samal, S. Effect of shape and size of filler particle on the aggregation and sedimentation behavior of the polymer composite. Powder Technol. 2020, 366, 43–51.Koumanova, B.; Drame, M.; Popangelova, M. Phosphate removal from aqueous solutions using red mud wasted in bauxite Bayer’s process. Resour. Conserv. Recy. 1997, 19, 11–20.
  39. Samal, S.; Vlach, J.; Kolinova, M.; Kavan, P. Micro-computed tomography characterization of isotropic filler distribution in magnetorheological elastomeric composites. In Advanced Processing and Manufacturing Technologies for Nanostructured and Multifunctional Materials III; The American Ceramic Society: Columbus, OH, USA, 2017.Pera, J.; Boumaza, R.; Ambroise, J. Development of a pozzolanic pigment from red mud. Cem. Concr. Res. 1997, 27, 1513–1522.
  40. Samal, S.; Škodová, M.; Blanco, I. Effects of filler distribution on magnetorheological silicon-based composites. Materials 2019, 12, 3017.Collazo, A.; Fernández, D.; Izquierdo, M.; Nóvoa, X.R.; Pérez, C. Evaluation of red mud as surface treatment for carbon steel painting. Prog. Org. Coat. 2005, 52, 351–358.
  41. Alkan, G.; Yagmurlu, B.; Cakmakoglu, S.; Hertel, T.; Kaya, S.; Gronen, L.; Stopic, S.; Frierich, B. Novel Approach for Enhanced Scandium and Titanium Leaching Efficiency from Bauxite Residue with Suppressed Silica Gel Formation. Sci. Rep. 2018, 8, 5676.Park, S.J.; Jun, B.R. Improvement of red mud polymer-matrix nanocomposites by red mud surface treatment. J. Colloid Interface Sci. 2005, 284, 204–209.
  42. Vind, J.; Malfliet, A.; Blanpain, B.; Tsakiridis, P.E.; Tkaczyk, A.H.; Vassiliadou, V.; Panias, D. Rare Earth Element Phases in Bauxite Residue. Minerals 2018, 8, 77.Chunming, G.; Nanr, Y. Effect of phosphate on the hydration of alkali-activated red mud–slag cementitious material. Cem. Concr. Res. 2000, 30, 1013–1016.
  43. Nie, Q.; Hu, W.; Huang, B.; Shu, X.; He, Q. Synergistic utilization of red mud for flue-gas desulfurization and fly ash based geopolymer preparation. J. Hazard. Mater. 2019, 369, 503.Ochsenkuhn, P.M.; Lyberropulu, T.; Ochsenkuhn, K.M.; Parissakis, G. Recovery of lanthanides and yttrium from red mud by selective leaching. Anal. Chim. Acta 1996, 319, 249–254.
  44. Kaußen, F.M.; Friedrich, B. Phase characterization and thermochemical simulation of (landfilled) bauxite residue (“red mud”) in different alkaline processes optimized for aluminum recovery. Hydrometallurgy 2018, 176, 49–61.Wang, S.; Boyjoo, Y.; Choueib, A.; Zhu, Z.H. Removal of dyes from aqueous solution using fly ash and red mud. Water Res. 2005, 39, 129–138.
  45. Klauber, C.; Gräfe, M.; Power, G. Bauxite residue issues: II. Options for residue utilization. Hydrometallurgy 2011, 108, 11–32.Smith, N.J.; Buchanan, V.E.; Oliver, G. The potential application of red mud in the production of castings. Mater. Sci. Eng. A 2006, 420, 250–253.
  46. Goodenough, K.M.; Wall, F.; Merriman, D. The rare earth elements: Demand, global resources, and challenges for resourcing future generations. Nat. Resour. Res. 2018, 27, 201–216.Li, P.; Miser, D.E.; Rabiei, S.; Yadav, R.T.; Hajaligol, M.R. The removal of carbon monoxide by iron oxide nanoparticles. Appl. Catal. B 2003, 43, 151–162.
  47. Binnemans, K.; Jones, P.T. Rare earths and the balance problem. J. Sustain. Metall. 2015, 1, 29–38.Lopez, E.; Soto, B.; Arias, M.; Nunez, A.; Rubinos, D.; Barral, T. Adsorbent properties of red mud and its use for wastewater treatment. Water Res. 1998, 32, 1314–1322.
  48. Konkanov, M.; Salem, T.; Jiao, P.; Niyazbekova, R.; Lajnef, N. Environment-Friendly, Self-Sensing Concrete Blended with Byproduct Wastes. Sensors 2020, 20, 1925.Altundoğan, H.S.; Altundoğan, S.; Tümen, F.; Bildik, M. Arsenic removal from aqueous solutions by adsorption on red mud. Waste Manag. 2000, 20, 761–767.
  49. Reid, S.; Tam, J.; Yang, M.; Azimi, G. Technospheric Mining of Rare Earth Elements from Bauxite Residue (Red Mud): Process Optimization, Kinetic Investigation, and Microwave Pretreatment. Sci. Rep. 2017, 7, 15252.Komnitsas, K.; Bartzas, G.; Paspaliaris, I. Efficiency of limestone and red mud barriers: Laboratory column studies. Miner. Eng. 2004, 17, 183–194.
  50. Samal, S. Preparation of synthetic rutile from pre-treated ilmenite/Ti-rich slag with phenol and resorcinol leaching solutions. Hydrometallurgy 2013, 137, 8–12.Bertocchi, A.F.; Ghiani, M.; Peretti, R.; Zucca, A. Red mud and fly ash for mine sites contaminated with As, Cd, Cu, Pb and Zn. J. Hazard. Mater. 2006, 134, 112–119.
  51. Alkan, G.; Schier, C.; Gronen, L.; Stopic, S.; Friedrich, B. A Mineralogical Assessment on Residues after Acidic Leaching of Bauxite Residue (Red Mud) for Titanium Recovery. Metals 2017, 7, 458.Genc, H.; Tjell, J.C.; McConchie, D.; Schuiling, O. Adsorption of arsenate from water using neutralized red mud. Colloid Interface Sci. 2003, 264, 327–334.
  52. Samal, S. Effect of high temperature on the microstructural evolution of fiber reinforced geopolymer composite. Heliyon 2019, 5, e01779.Yalcin, N.; Sevinc, V. Utilization of bauxite waste in ceramic glazes. Ceram. Int. 2000, 26, 485–490.
  53. Catauro, M.; Tranquillo, E.; Barrino, F.; Dal Poggetto, G.; Blanco, I.; Cicala, G.; Ognibene, G.; Recca, G. Mechanical and thermal properties of fly ash-filled geopolymers. J. Therm. Anal. Calorim. 2019, 138, 3267.
  54. Chen, X.; Guo, Y.; Ding, S.; Zhang, H.; Xia, F.; Wang, J.; Zhou, M. Utilization of red mud in geopolymer-based previous concrete with function of adsorption of heavy metal ions. J. Clean. Prod. 2019, 207, 789.
  55. Ascensao, G.; Seabra, M.P.; Aguiar, B.J. Labrincha. J.A. Red mud-based geopolymers with tailored alkali diffusion properties and pH buffering ability. J. Clean. Prod. 2017, 148, 23.
  56. Kumar, S.; Kumar, R.; Bandopadhyay, A. Innovative methodologies for the utilization of wastes from metallurgical and allied industries. Resour. Conserv. Recycl. 2006, 48, 301–314.
  57. Jayasankar, K.; Ray, P.K.; Chaubey, A.K.; Padhi, A.; Satapathy, B.K.; Mukherjee, P.S. Production of pig iron from red mud waste fines using thermal plasma technology. Int. J. Miner. Metall. Mater. 2012, 19, 679–684.
  58. Lim, K.; Shon, B. Metal Components (Fe, Al and Ti) recovery from red mud by sulfuric acid leaching assisted with ultrasonic waves. Int. J. Emerg. Technol. Adv. Eng. 2015, 5, 25–32.
  59. Voßenkaul, D.; Birich, A.; Müller, N.; Stoltz, N.; Friedrich, B. Hydrometallurgical processing of eudialyte bearing concentrates to recover rare earth elements via low-temperature dry digestion to prevent the silica gel formation. J. Sustain. Metall. 2017, 3, 79–89.
  60. Ochsenkuhn, P.M.; Lyberropulu, T.; Ochsenkuhn, K.M.; Parissakis, G. Recovery of lanthanides and yttrium from red mud by selective leaching. Anal. Chim. Acta 1996, 319, 249–254.
  61. Smith, N.J.; Buchanan, V.E.; Oliver, G. The potential application of red mud in the production of castings. Mater. Sci. Eng. A 2006, 420, 250–253.
  62. Schwarzenbach, G.; Muehlebach, J.; Mueller, K. Peroxo complexes of titanium. Inorg. Chem. 1970, 9, 2381–2390.
  63. Antonijević, M.; Dimitrijević, M.; Janković, Z. Leaching of pyrite with hydrogen peroxide in sulphuric acid. Hydrometallurgy 1997, 46, 71–83.
  64. Li, P.; Miser, D.E.; Rabiei, S.; Yadav, R.T.; Hajaligol, M.R. The removal of carbon monoxide by iron oxide nanoparticles. Appl. Catal. B 2003, 43, 151–162.
  65. Lopez, E.; Soto, B.; Arias, M.; Nunez, A.; Rubinos, D.; Barral, T. Adsorbent properties of red mud and its use for wastewater treatment. Water Res. 1998, 32, 1314–1322.
  66. Altundoğan, H.S.; Altundoğan, S.; Tümen, F.; Bildik, M. Arsenic removal from aqueous solutions by adsorption on red mud. Waste Manag. 2000, 20, 761–767.
  67. Yao, L.; Gao, W.; Ma, X.; Fu, H. Properties Analysis of Asphalt Binders Containing Bayer Red Mud. Materials 2020, 13, 1122.
  68. Halász, J.; Hodos, M.; Hannus, I.; Tasi, G.; Kiricsi, I. Catalytic detoxification of C2-chlorohydrocarbons over iron-containing oxide and zeolite catalysts. Colloids Surf. A 2005, 265, 171–177.
  69. Sayan, E.; Bayramoglu, M. Statistical modeling of sulfuric acid leaching of TiO2 from red mud. Hydrometallurgy 2004, 71, 397–401.
  70. Wang, L.; Sun, N.; Tang, H.; Sun, W. A Review on Comprehensive Utilization of Red Mud and Prospect Analysis. Minerals 2019, 9, 362.
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