Article

Gallium and Vanadium Extraction from Red Mud of Turkish Alumina Refinery Plant: Hydrogarnet Process

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  • SDU/Beijing University of Chemical Technology/Satbayev University/Nazarbayev University
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... The main components of red mud, for example, aluminum [8], sodium [8], iron [9], and titanium [10], were extracted or separated as resources. The leaching behavior of these elements from red mud was investigated [11]. Meanwhile, trace valuable elements in red mud including rare earth elements [12,13], scandium [14], gallium [11,15], vanadium [11,16], and lithium [17], were also reported as potential resources. ...
... The leaching behavior of these elements from red mud was investigated [11]. Meanwhile, trace valuable elements in red mud including rare earth elements [12,13], scandium [14], gallium [11,15], vanadium [11,16], and lithium [17], were also reported as potential resources. Concentrations of lithium in different red mud samples were determined as a trace/minor component with a wide range from several tens to hundreds μg/g [18][19][20] depending on the raw material, bauxite ore [21]. ...
... The leaching behavior of these elements from red mud was investigated [11]. Meanwhile, trace valuable elements in red mud including rare earth elements [12,13], scandium [14], gallium [11,15], vanadium [11,16], and lithium [17], were also reported as potential resources. Concentrations of lithium in different red mud samples were determined as a trace/minor component with a wide range from several tens to hundreds μg/g [18][19][20] depending on the raw material, bauxite ore [21]. ...
Article
Bauxite residue (red mud) is an alkaline waste derived from the industrial process for extraction of alumina from bauxite ore. Some bauxite residues contain considerable concentrations of critical metals, for example, rare earth elements. Lithium in red mud was also reported as a potential resource. In the current study, a Li-rich red mud was leached using acetic acid to investigate the leaching behavior of lithium followed by neutralizing with hydrochloric or oxalic acid. By neutralizing red mud using diluted hydrochloric acid (0.01 mol/L), 58.04–60.27% of lithium was leached using 25% acetic acid at 95 °C for 60 min. In the meantime, more than 95% of sodium and 85% of calcium were also dissolved in the leachate solution. While oxalic acid (0.5 mol/L) was used to neutralize red mud prior to acetic acid leaching, lithium performed lower leaching efficiencies (42.41–46.88%) in comparison of using of hydrochloric acid–neutralized red mud. Nevertheless, these leaching efficiencies of lithium were close to that of calcium and much higher than those of sodium under the condition. In this study, 25% (v/v) of acetic acid, at 85 °C for 60 min, was demonstrated as optimum conditions for lithium extraction from oxalic acid–neutralized red mud using acetic acid. The results would be useful and of interest for lithium recovery and purification from red mud.
... Numerous studies have focused on the utilization of bauxite residue as a source for the production of major elements (e.g., blast furnace for pig iron production [10][11][12][13][14]) or as a source of rare earth elements (REEs) [15][16][17][18][19] as well as the combination of these [20]. Fewer efforts have been made to use the bauxite residue as a secondary source of other CRMs such as V and Ga [18,21,22]. ...
... Previous studies on extraction of Ga from bauxite residue have been based on mineral acids [18,22] and on alkaline solutions from bauxite residue (hydrogarnet process) [21]. In the latter, the extraction of Ga from bauxite residue was carried out in high modulus alkaline solution (240 g/L Na 2 O; α к = 30) at high temperatures (240-260 °C) in the presence of lime followed by treatment of the leachate by CO 2 -enriched air [21]. ...
... Previous studies on extraction of Ga from bauxite residue have been based on mineral acids [18,22] and on alkaline solutions from bauxite residue (hydrogarnet process) [21]. In the latter, the extraction of Ga from bauxite residue was carried out in high modulus alkaline solution (240 g/L Na 2 O; α к = 30) at high temperatures (240-260 °C) in the presence of lime followed by treatment of the leachate by CO 2 -enriched air [21]. ...
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Bauxite residue, the byproduct of alumina production, may potentially be a valuable source of strategically important metals, e.g. Gallium. Ga is considered critical element for the EU. To ensure adequate supply of Ga for the future, secondary sources such as bauxite residue should be exploited with efficient extraction methods. Therefore, in this study, mineral acids (H 2 SO 4 , HCl, and HNO 3) and an organic acid (H 2 C 2 O 4-oxalic acid), were evaluated for their efficiencies to extract Ga from bauxite residue. Using H 2 C 2 O 4 , the highest Ga leaching efficiencies were achieved, compared to other acids. The achieved leaching experimental results were considered for the construction of a design of experiment (DOE) model to achieve optimal conditions for Ga extraction using H 2 C 2 O 4. These values were validated by experiments which resulted in ~ 94% accuracy. In the second part of the study, using pure Ga solution, the adsorption of Ga onto zeolite HY was studied. The effects of adsorbent dosage, temperature, and contact time on the adsorption of Ga from solution by zeolite HY were studied. The obtained adsorption experimental results were used to construct a DOE model to achieve optimal conditions for Ga adsorption on to zeolite HY. The DOE-achieved optimal conditions were evaluated by experiments in pure Ga solution, which resulted in an efficiency of ~ 99.4 %. In the third stage, the bauxite residue was leached in H 2 C 2 O 4 under the optimal DOE conditions which resulted in 71% efficiency; thus the resulting bauxite residue solution was subjected to adsorption using zeolite HY under the optimal DOE conditions achieved. The Ga adsorption onto the zeolite was only 16% compared to the Ga adsorption of 99.4 % under the pure Ga solution, thus, representing the influences of the other leachates in the solution, which are minimizing the Ga adsorption onto the zeolite HY and providing an opportunity for future studies on the different mechanisms involved.
... Stage II of the carbonization process was conducted at 70 • C for 300 min [34]. After each stage, the pulp was incubated for 1 h without a carbon dioxide supply. ...
... Stage II of the carbonization process was conducted at 70 °C for 300 min [34]. After each stage, the pulp was incubated for 1 h without a carbon dioxide supply. ...
Article
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This article presents the results of studies on the distribution of rare metals among the products of the alkali sulfate processing of nepheline syenites. In response to the limited reserves of Bayer bauxite in the alumina industrial production region of Kazakhstan, the feasibility of using alternative alumina-containing nonbauxite raw materials was investigated. The most promising nonbauxite raw materials in Kazakhstan are nepheline and kaolinite clays. At present, there is no effective technology for processing nepheline ores. This article describes a proposed complex technology involving nepheline processing with the associated extraction of gallium and vanadium. The technology includes the activation of raw materials, followed by two-stage leaching, where potassium is extracted in the first stage. The sludge and solution obtained from the second stage of the leaching process are utilized for calcium silicate production and two-stage carbonization, respectively. In the first stage, aluminum hydroxide is extracted, and, in the second stage, a concentration of rare metals, such as gallium and vanadium, is obtained. Vanadium is extracted from the solution via crystallization, and gallium is extracted via electrodeposition. Overall, 38.48% of the Ga2O3 and 56.12% of the V2O5 are recovered from raw nepheline syenite. A technological scheme of the developed technology is presented in this article.
... Efficient recovery (99%) of REEs such as Ce and La from red mud using H2SO4 solutions has been reported [119]. Abdulvaliyev et al. [120] explored on use of the Bayer-Hygrogarnet treatment for the processing of red mud to recover the contaminated metal values, such as Na2O, Al2O3, Ga, and V2O5 by using autoclave leaching with lime [120]. The results showed the recovery of vanadium as ammoniametavanadate by using precipitation with ammonium sulphate and sulfuric acid solutions. ...
... Efficient recovery (99%) of REEs such as Ce and La from red mud using H2SO4 solutions has been reported [119]. Abdulvaliyev et al. [120] explored on use of the Bayer-Hygrogarnet treatment for the processing of red mud to recover the contaminated metal values, such as Na2O, Al2O3, Ga, and V2O5 by using autoclave leaching with lime [120]. The results showed the recovery of vanadium as ammoniametavanadate by using precipitation with ammonium sulphate and sulfuric acid solutions. ...
Article
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Aluminum is produced from its primary bauxite ore through the Bayer process. Although Al is important nowadays in the development of humanity, its production leads to the generation of a huge amount of waste, called red mud. Globally, the estimation of the stock of red mud is about 4 billion tons, with about 10 million tons located in Turkey. The presence of rare-earth elements (REEs) in crucial materials such as red mud makes it a major source of these elements. A number of methods have been developed for treating red mud, which are employed globally to recover valuable products. The application of a suitable method for REE extraction from red mud is a way to overcome the supply risk, contributing to reducing the environmental issues linked to red mud pollution. The current review summarizes the research on red mud processing and examines the viability of recovering REEs from red mud sustainably, utilizing hydrometallurgy and biohydro-metallurgy.
... As a diprotic acid, the acidity of H 2 SO 4 is generally higher than the mono-protic acids (such as HCl and HNO 3 ), which decides the acid leaching efficiency. Abdulvaliyev et al. (2015) adopted an alkali leaching-carbonization process to treat RM as shown in Fig. 20. The RM firstly reacts with sodium alumina solution with a high molecular ratio of 30 at 240-260 • C to prepare the gallium-rich solution, and then the purified solution is used to recover aluminum hydroxide and gallium-rich slag by a twostage carbonization process. ...
... Flow chart of alkali leaching-carbonization process(Abdulvaliyev et al., 2015). ...
Article
As a bulk solid waste with high alkalinity, red mud (RM) not only occupies a large amount of land and requires high maintenance costs, but also unavoidably generates serious hazards to the surrounding ecological environment. The comprehensive treatment of RM has become an enormous challenge for the green, low-carbon and high-quality development of the global alumina industry. To minimize the RM destruction to the ecology and the waste of secondary resources, the sustainable utilization of RM was widely investigated in the past decades, especially for the recovery of valuable metals. This paper systematically summarized the research status of recycling valuable metals (Al, Fe, Na, Ti, Sc, Ga, V and RE) from RM in recent years. The recycling technology mainly includes physical beneficiation, hydrometallurgy, pyrometallurgy and electrodialysis. The technical principles and characteristics as well as the current problems of various recovery processes from RM were comprehensively introduced, and the future development directions of sustainable utilization were also prospected. The advantages and disadvantages based on the different aspects of recovery efficiency, energy consumption and environmental impact were also discussed. The proposal of new technologies for the harmless, high-value and full utilization of RM is beneficial to the future research on the comprehensive utilization of bulk industrial solid wastes.
... [12][13][14][15] Depending on the origin of the residues, they may contain considerable amounts of CRMs, in particular REE and Sc. [16][17][18][19][20][21] Bauxite residues (also known as 'red mud', 'Bayer process tailings' or 'bauxite process tailings') are generated from alumina production where bauxite is digested in hot NaOH solution via the Bayer process. 22 The production of 1 tonne of alumina generates between 1 and 1.5 tonnes of bauxite residue. ...
... Various techniques have been used for the recovery of elemental metal or its suitable compound from the concentrate: metal compounds by crystallization or ionic precipitation, metals/metal compounds by reduction with gas, metals by electrochemical reduction and metals by electrolytic reduction. 112 Reference Wang et al. 55 Qu and Lian 21 Borra et al. 17 Ujaczki et al. 20 Mohapatra et al. 19 Petrakova et al. 82 Abdulvaliyev et al. 16 Alumina production in wileyonlinelibrary.com/jctb ...
Article
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Since the world economy has been confronted with an increasing supply risk of critical raw materials (CRMs), there is a major interest in identifying alternative secondary sources of CRMs. Bauxite residues from alumina production are available at a multi‐million ton scale worldwide. So far, attempts have been made to find alternative re‐use applications for bauxite residues, for instance in cement / pig iron production. However, bauxite residues can also be an untapped secondary source for CRMs. Depending on their geologic origin and processing, bauxite residues can contain considerable amounts of valuable elements. The obvious primary consideration for CRM recovery is the economic value of the materials contained. However, there are further benefits from re‐use of bauxite residues in general, and from CRM recovery in particular. These go beyond monetary values (e.g. reduced investment / operational costs by savings in disposal). For instance, benefits for the environment and health can be achieved by abatement of tailing storage as well as by reduction of emissions from conventional primary mining. Whereas certain tools (e.g. life‐cycle analysis) can be used to quantify the latter, other benefits (in particular sustained social and technological development) are harder to quantify. This review evaluates strategies of bauxite residue re‐use/re‐cycle and identifies associated benefits beyond elemental recovery. Further, methodologies to translate risks and benefits into quantifiable data are discussed. Ultimately, such quantitative data are a prerequisite for facilitating decision making regarding bauxite residue re‐use/re‐cycle and a stepping stone towards developing a zero waste technology.
... The aforementioned Ga-bearing resources and the corresponding extraction processes, optimum recovery efficiencies, end products and applied scales are summarized in Table 3 (Figueiredo et al., 2002;Zhao et al., 2012;Gladyshev et al., 2015;Carvalho et al., 2000;Abisheva et al., 2012;Carvalho et al., 2000;Liu and Li, 2015;Abdulvaliyev et al., 2015;Klein et al., 1975;Zheng and Gesser, 1996;Gutiérrez et al., 1997;Oriol et al., 2007;Liu et al., 2016;Kinoshita et al., 2011;Gu et al., 2014;Swain et al., 2015a,b;Lee and Nam, 1998;Lu et al., 2015;Xu et al., 2004Xu et al., , 2007. ...
... Hydrometallurgy 174 (2017) 105-115 Table 3 Summary of gallium-bearing resources and extracting processes. Figueiredo et al., 2002;Zhao et al., 2012;Gladyshev et al., 2015;Carvalho et al., 2000;Abisheva et al., 2012;Carvalho et al., 2000;Liu and Li, 2015;Abdulvaliyev et al., 2015;Klein et al., 1975;Zheng et al.,1996;Gutiérrez et al., 1997;Oriol et al., 2007;Liu et al., 2016;Kinoshita et al., 2011;Gu et al., 2014;Swain et al., 2015a,b;Lee and Nam, 1998;Lu et al., 2015;Xu et al., 2007Xu et al., , 2004 concentration. Simultaneous recoveries of other valuable metals from coal ash fly and red mud should also be considered during the Ga recycling process, which would make the technology even more economically feasible. ...
Article
Gallium (Ga) is extensively employed in integrated circuits and advanced electronic devices as it provides the benefits of low energy consumption and high computation speeds. However, the Ga-bearing host minerals are scarce in nature. Ga occurs in combination with several minerals, mainly including aluminum, zinc, iron ores and coals, of which bauxite, zinc ores and coals are the primary original sources of Ga currently. Mining minerals for the sole extraction of Ga is not economical due to the low concentration of Ga. Accordingly, Ga is mainly recovered as a by-product from the processing of minerals. The current main commercial resources of Ga are Bayer liquor and zinc residue, which contribute to nearly all of the worldwide Ga production. The production of low-grade (99.99% pure) Ga has been increasing at an average rate of 7.4% p.a. for the past four decades and amounted to 375 tons in 2016. It is estimated to increase by 20-fold by the year 2030 compared to the yield of 275 tons in 2012. The mounting worldwide demand for Ga necessitates the search for additional resources and recovery technologies for this particular element. Apart from the Bayer liquor and the zinc residue, there are several other Ga-resources, which include red mud, coal fly ash, Ga-bearing electronics industrial waste, and flue dust from electric furnaces at phosphorus factories. Based on the chemical properties of Ga, it is evident that both strong acidic/basic conditions and high temperatures favor the efficient extraction of Ga from its corresponding minerals. Several hydrometallurgical processes based mainly on acid/alkaline leaching along with solution purification and recovery (e.g. ion exchange, solvent extraction and precipitation) have been proposed for Ga extraction from these resources. In this paper, the current status of Ga recovery was reviewed and specific examples were utilized for each resource to discuss the extraction methods, the recoveries and the optimum Ga-recovery conditions for each resource. Additional research appears to be necessary to establish a highly efficient and environmentally friendly process to recover Ga from these resources.
... Известен способ извлечения ванадия из магнетита с помощью биовыщелачивания с использованием биогенных органических кислот, что указывают путь к тестированию различных видов микроорганизмов для оптимизации процесса извлечения [43]. ...
Article
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The article discusses the methods of processing vanadium-containing raw materials, including methods of pre-sintering and leaching of raw materials, extraction and precipitation of vanadium-containing solutions. In addition, the specific methods used for each type of vanadium-containing raw materials are described, with a description of their advantages and limitations. The article also briefly analyzes a number of the main influencing factors and mechanisms of various processes. Some research prospects are proposed to improve the methods of vanadium concentration from vanadium-containing raw materials. The article considers the potential of extraction and processing of vanadium-containing black shale ore, as well as vanadium-containing titanomagnetite ores. Spent vanadium catalysts used in petrochemical processes can be a potential source for vanadium extraction. In addition, vanadium-containing bauxite raw materials, oil and steel production slags can be promising raw materials for further extraction of vanadium. The article presents methods for processing vanadium-containing raw materials, including methods of pre-sintering and leaching of raw materials, extraction and precipitation of vanadium-containing solutions. In addition, the specific methods used for each type of vanadium-containing raw materials are described, with a description of their advantages and limitations. The article also examines the potential of extraction and processing of vanadium-containing black shale ore, vanadium-containing titanomagnetite ores as a potential source for vanadium extraction. Vanadium-containing bauxite raw materials and steelmaking slags can also be promising raw materials for further extraction of vanadium. Ванадий является переходным металлом и важней-шим элементом, широко применяемым в различных отраслях промышленности, включая производство стали [1], накопление энергии [2] и катализ [3]. Его уникаль-ные свойства, такие как высокая прочность, отличная коррозионная стойкость и способность образовывать стабильные соединения, делают его незаменимым в этих отраслях [4]. Цель данного обзора-анализ и системати-зация существующих методов переработки ванадийсо-держащих руд, выявление их достоинств и недостатков. Рассмотрены как традиционные пиро-и гидрометаллур-гические схемы, так и современные комбинированные технологии, включающие окислительный обжиг, выще-лачивание и экстракционное извлечение ценных компо-нентов. Особое внимание уделено инновационным ре-шениям, позволяющим повысить степень извлечения ванадия и снизить экологическую нагрузку производ-ства. Проведенный анализ методов переработки позво-лит оптимизировать существующие и разработать новые ресурсосберегающие технологии комплексной перера-ботки ванадийсодержащего сырья. Вследствие этого в последние годы значительное внимание уделяется добы-че и переработке ванадия из различных источников. Ввиду того, что спрос на ванадий продолжает расти, эффективная переработка ванадиевых руд и промыш-ленных отходов приобретает первостепенное значение для обеспечения устойчивой цепочки поставок этого важного ресурса. Далее на рисунке 1 представлена схема извлечения ванадия из ванадийсодержащего сырья и перервода его в оксид ванадия [5-13], состоящая из четырех стадий, та-ких как обжиг, выщелачивание, извлечение и прокалива-ние. Для каждой из стадий представлены процессы, ноб-ходимые для реализации данных стадий. Ванадий может быть извлечен из руд и материалов с помощью пирометаллургических процессов [14]. Один из распространенных методов известен как процесс спе-кания-выщелачивания. В этом процессе руду или мате-риал сначала спекают при высоких температурах для превращения минералов ванадия в водорастворимые соединения. Затем обожженный материал выщелачивают соответствующим раствором для растворения соедине-ний ванадия. Полученный раствор подвергается даль-нейшей переработке для удаления примесей и извлече-ния ванадия. Это может включать осаждение, фильтра-цию и другие методы разделения. В конечном итоге ванадий получают в виде соединения высокой чистоты, например, оксида ванадия (V) [15, 16].
... Literature reviews indicate that most of the extractions of REEs from red mud have been experimentally investigated using hydrometallurgy methods involving leaching in acid solution followed by retrieval of REEs from the solution using precipitation, solvent extraction or ion exchange adsorption (Zhang et al. 2016;Akcil et al. 2018;Archambo and Kawatra 2021). Recovery of titanium and gallium from red mud have also been experimentally investigated via the hydrometallurgy route (Mehta and Patel 1951;Kasliwal and Sai 1999;Agatzini-Leonardou et al. 2008;Ghorbani and Fakhariyan 2013;Abdulvaliyev et al. 2015;Huang et al. 2016;Alkan et al. 2018;Xue et al. 2019). Extraction of valuable elements from red mud has also been pursued at an industrial scale. ...
Article
The Western Indonesia Bauxite Province in Kalimantan forms a lateritic bauxite region with a complex history and poorly known sustainable metal contents within the bauxite residue. Bauxite residue produced using the Bayer process contains notable scandium. We present new geochemistry, mineralogical, and geological data from the lateritic bauxite and red mud from the active mine and deposit, which aims to investigate the behavior of critical elements during weathering. The geochemical analysis and translated isocon results have shown that the content of scandium in red mud is higher than the average concentration of crustal rocks and is concentrated in the ferrite layer and bauxite residue. A positive correlation between the existence of iron oxyhydroxide mineral in residual iron-rich layer and red muds with the rare earth elements (REE) and scandium concentrations may be interpreted as a scavenging effect of mobile REE. The weathering and leaching processes in bauxite allows the adsorption of the trivalent scandium cation (Sc ³⁺ ) on goethite and are followed by the ionic substitution with other trivalent cations in the crystal of hematite. The study illustrates the importance of understanding processes during weathering and laterization for geochemical processes and rare earth elements exploration in tropical areas. Thematic collection: This article is part of the Geochemical processes related to mined, milled, or natural metal deposits collection available at: https://www.lyellcollection.org/topic/collections/geochemical-processes-related-to-mined-milled-or-natural-metal-deposits Supplementary material: https://doi.org/10.6084/m9.figshare.c.6689139
... As reported (Rinat et al. 2015), during the hydrogarnet formation, as the degree of substitution of [OH] − by [SiO 4 ] 4− gradually increased, the hydrogarnet synthesized was structurally tighter and more stable, which was unfavorable for its carbonation and decomposition. For hydrogarnets with higher SiO 2 substitution degrees, the CaO use efficiency during calcification can be enhanced; but, from the perspective of carbonation and decomposition extent, it is harder to generate hydrogarnets with high SiO 2 substitution degrees. ...
Article
Full-text available
Hydrogarnets are vital intermediate products in the calcification- carbonation method, which is designed for Bayer red mud treatment. Their carbonation performance greatly depends on SiO2 substitution. In this study, different SiO2-substituted hydrogarnets were synthesized and characterized. Then, batch experiments were performed to evaluate the potential effects of important parameters such as CO2 pressure, and SiO2 substitution degree (x) on the carbonation process. The SiO2 substitution degrees of the hydrogarnets synthesized at 60, 120, 180, and 240°C were 0.27, 0.36, 0.70, and 0.73, respectively. As the SiO2 substitution degree increased, the hydrogarnet carbonation extents gradually declined. With an increase in CO2 pressure, the hydrogarnet carbonation percentages increased gradually and rose from 80.33% to 98.19% within 120 min. The phases detected in the carbonized products were strip-like aragonite as well as some calcite; the Al-rich and Si-rich phases in the carbonized products were amorphous.
... Several authors have discussed BR as secondary resources for REM and reported exploitation strategies through research and development. Most of the research reported in the literature is focused on either valorization or selective metal recovery from BR (Abdulvaliyev et al., 2015, Borra et al., 2016. When selective metal recovery is the interest, the motivation is focused on base metal or selective to Sc or La like metals only. ...
Article
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Bauxite residue (BR), simultaneously an environmental challenge as well as known to be a secondary resource for resources various valuable metals like Ti, V, Ga, and rare earth metal (REM). Lack of understanding and technology detects BR to be stockpiled which is counterproductive considering the environment, land scarcity, and management of BR inventories. As BR remains unexploited, significant amounts of REMs in BR remain unlocked, which are critical metals from green energy, environmental sustainability, and supply chain bottleneck perspective. Our current investigation analyses the potential of BR as secondary resources and quantity and worth of REM being remains unlocked. The quantitative content of global bauxite, alumina, and BR production during the last 5 decades have been analyzed. Also, plausible BR generation in the next 3 decades has been estimated. Considering the content of REM in BR amount of REM either stockpiled or to be stockpiled along with BR has been analyzed. Our study indicated about 9.14 million tons of REM remain locked in the stockpiled BR, 31.24 million tons of REM remain locked in the bauxite reserve. The worth of worldwide REM oxide remains unexploited in bauxite reserves and locked in stockpiled BR could be approximately $5000 billion, potentially can meet current and project demand of REM abundantly.
... Earlier studies demonstrated that BR present a source for rare, very valuable elements such as gallium (Abdulvaliyeva et al., 2015) and other such as aluminium, iron or silica (Balomenos et al., 2017) (Jaspert et al., 2016). The viability of the production of pig iron and GBFS-like slag from BR was demonstrated with this study. ...
Article
This study investigates the composition and reactivity of two GBFS-like slags produced from bauxite residue (BR). The composition of the slags was analysed using a multi method approach. The hydraulic reactivity was assessed in Portland composite cement and with the addition of anhydrite, limestone and combinations thereof. The presented approach is further discussed in the context of the full valorisation of BR and the economic as well as environmental implications. Both slags demonstrated a good strength contribution at a 25% substitution rate. Both failed the minimum strength requirements for GBFS according to EN 15167–1, using a 50% substitution rate. Anhydrite and limestone additions improved the early strength development. This work further demonstrated that it is possible to convert 100% BR to valuable products. But the production of slags with a GBFS-like chemistry required the use of high quantities of slag-forming agents. Also, the process will be energy intensive and costly. Still, the approach can be economically viable, as several valuable products can be generated. The possible avoidance of landfilling or even torecovery landfill capacities presents another important economic benefit.
... Subsequent purging with CO 2 resulted in complete gallium precipitation. Another study by Abdulvaliyev et al. [20] focused on the treatment of coal fly ash red mud originating from an alumina refinery plant. Prior to CO 2 carbonization, silica was removed by the addition of lime milk (hydrogarnet process). ...
Article
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In this article, we examine the selective hydrometallurgical extraction of gallium from pyrolyzed smartphones. Gallium-enriched pyrolysis residue originating from pyrolyzed smartphones was leached using NaOH and gaseous oxygen at elevated temperatures and pressures. The high content of organic carbon in the material strongly influenced the leaching performance. Oxygen, which is indispensable for the dissolution of gallium, also oxidized the organic carbon in the feed so that CO2 was released, which had a neutralizing effect on the alkaline solution. As a result, the CO2 formation complicated the accurate process control as the leaching temperature increased. The highest gallium yield of 82% was obtained at 180 °C, 5 g/L NaOH and 5 bar oxygen pressure. Decreased temperatures, NaOH concentrations and oxygen pressures resulted in lower leaching yields but with a higher selectivity for Ga. Temperatures higher than 180 °C resulted in extensive carbon oxidation, NaOH consumption and the coextraction of Cu and Ag. We propose that those conditions also facilitated the formation of water-soluble organic compounds, which would also influence the metal dissolution.
... Figure 1(a) and (b), depicts the rate of red mud production as well as cumulative inventory trend for the years 1950years -2000years and 2001years -2018 represents the global red mud management trend Table 2. Summary of global alumina production during 2008-2017 (thousand metric tons), adapted from U.S. Geological Survey (2015,2016,2017,2019) and Bray (2016Bray ( , 2018. Country 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 Australia 19,321 19,948 19,956 19,399 21,357 21,528 20,474 20,097 20,681 20,486 Azerbaijan 165 80 -6 102 -----Bosnia and Herzegovina 294 192 269 262 202 176 171 251 188 180 Brazil 7,822 8,618 9,433 10,306 10,321 9,942 10,404 10,452 10,886 10,900 Canada 1,370 1,125 1,301 1,471 1,498 1,555 1,563 1,561 1,567 1,570 China 22,800 23,800 29,000 34,100 37,700 47,000 51,300 58,978 60,907 69,017 France 630 348 481 524 430 315 300 300 300 300 Germany 1,395 1,154 1,485 2,355 2,331 2,244 1,910 1,910 1,900 1,900 Greece 772 719 725 810 784 812 814 807 821 810 Guinea 593 530 597 574 150 ---- 3. Advantages and weaknesses of the existing red mud disposal/management process (Evans, 2016;Greg Power & Klauber, 2009;Power et al., 2009Power et al., , 2011 (Abdulvaliyev et al., 2015;Evans, 2016;Khairul et al., 2019;Lu et al., 2018;Power et al., 2011;Ujaczki et al., 2019). ...
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Significantly unexploited red mud contains 0.5–1.7 kg/ton of rare earth metals (REMs) and 14–45% Fe, 5–14% Al, 1–9% Si, 1–6% Na, and 2–12% Ti which is currently being stockpiled. Reasonably, the red mud can be a suitable secondary resource of REMs, and other valuable metals, if not for the contained base metals. Stockpiled red mud locks down these technologically important and supply chain critical metals. Though quantitatively minor, the value perspective of REMs in red mud is significant. Global red mud inventory could reach 4 billion tons by 2020 and being generated 120–150 million tons per year worldwide. Analysis indicated that industrial-scale valorization could unlock approximately $4.3 trillion worth of REMs from stockpiled red mud. The current review discusses the valorization of red mud through metal value recovery which is an industrial waste circular economy challenge. Unlike other reported reviews, the current review intensively discusses circular economy challenges and opportunities associated with the red mud valorization. Finally, a suitable conceptual sequential metal recovery process has been proposed based on a comprehensive review of various processes which can technically be a feasible process for sequential recovery of various metal values from the red mud. Comprehensive cutting-edge research, broader risk assessment, and cost and benefit analysis of the proposed process can ensure broader valorization. Broader valorization can address several issues through the proposed process like; (i) metal value recovery, (ii) REMs circular economy, (iii) closed-loop process with the industry, and (iv) lower the futuristic carbon economy, simultaneously.
... Red mud (RM) is a highly alkaline solid waste generated in the process of alumina extraction from bauxite ores [1]. The total quantity of RM stored in the world has currently reached 4 billion tons, and it is predicted to increase to 150 million tons per annum. ...
Article
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In the present study, using Aspergillus niger and Penicillium tricolor, the influence of the selected parameters, including sucrose concentration, inoculation size of spores, pulp density, and pre-culture time, on the bioleaching efficiency (biomass, organic acids production, and vanadium extraction, respectively) of red mud were studied. The bioleaching kinetics under optimal conditions were also explored. Sucrose concentration showed a positive linear effect on bioleaching efficiency below 143.44 and 141.82 g/L using A. niger and P. tricolor, respectively. However, a higher concentration was unfavorable for vanadium extraction. The inoculation size of spores showed an insignificant effect on both biomass and vanadium extraction if it exceeded the lowest coded levels (0.5 × 107/mL). Red mud pulp density showed a negative effect on the bioleaching efficiency of A. niger but a positive effect on organic acids production and vanadium extraction of P. tricolor. A pre-culture was indispensable for A. niger but not for P. tricolor due to the fact of its isolation from the red mud examined in this study. The kinetics analysis showed that the leaching rate of vanadium followed a two-domain behavior: initially, a rapid leaching period of approximately 10–15 days and, subsequently, a slow leaching period. Considering the change of the particles’ appearance as well as in the elemental composition of the bioleached red mud, it is speculated that the rate of leaching agents through the silicon minerals was the rate-limiting step of dissolution kinetics under the fungal bioleaching process.
... As the red mud has high alkalinity, large specific surface area and good absorbability, it can be applied to the solidification of heavy metal contaminated soil (Wansom et al., 2006;Song, Suo, Dong, & Chen, 2018). Moreover, the reactivity of red mud has a great influence on the curing effect (Abdulvaliyev, Akcil, & Gladyshev, 2015). As the red mud produced by the Bayer process after many washing cycles, settling and filtering, most of minerals in its particles have lost their reactivity. ...
Article
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As a static method for testing pollution and strength of soil, the resistivity method has been used by many scholars, whereas few studies have been carried out on dynamic deformation monitoring by this method. To study the pressure sensitive properties of copper contaminated soils solidified by modified red mud, a series of unconfined compression tests were conducted. The compressive stress, strain and electrical resistivity in whole process were determined. Relationship between the resistivity and the parameters including stress, strain, red mud content, copper content, and curing age were analysed. Then the mechanism of electrical resistivity is revealed. Results indicate the stress-resistivity change rate follows the same trend as the stress-strain curve. The resistivity change rate follows the same rule as the strain change, indicating that the electrical resistivity can reflect the strain indirectly. The higher red mud content is, the better pressure sensitive properties of solidified soil is. A proper amount of copper can improve the pressure sensitivity of solidified soil, while excessive copper ions can reduce pressure sensitivity of solidified soil. These changes can be attributed to the pore water, iron oxide in red mud, tunnel conductive effect and conductivity percolation.
... As a kind of strategic resources, gallium and its compounds are widely used in semiconductors (Kim et al., 2015), photoelectric materials (Kente and Mhlanga, 2016;Liu and Wang, 2018), medicine Maurer et al., 2016), solar cells Xiang et al., 2017), liquid metal alloys (Khondoker and Sameoto, 2016) and catalysts (Iqbal et al., 2016). However, there are no pure gallium ores in nature, and gallium usually exists in sphalerite (Liu et al., 2017b;Liu et al., 2016), bauxite (Abdulvaliyev et al., 2015;Zhao et al., 2016) and coal fly ash (Funari et al., 2017;Qin et al., 2015). Therefore, gallium is generally recovered as a byproduct during the metallurgical process. ...
Article
In the present work, an α-aminophosphonate extractant di(2-ethylhexyl) [N-(2-ethylhexyl)aminomethyl] phosphonate (Cextrant 230, L) was applied for the selective extraction and recovery of Ga(III) from the chloride solutions. The extraction of Ga(III) was compared with that of other metal ions such as Fe³⁺, Fe²⁺, Zn²⁺, Al³⁺, Mg²⁺ and Sn²⁺. The extracted complex of Ga(III) was deduced to be HGaCl4·L. The extraction equilibrium constant and thermodynamic parameters (ΔG, ΔH and ΔS) were calculated. The positive value of ΔH indicates that the extraction reaction of Ga(III) is an endothermic process. The loading capacity of 30% (v/v) Cextrant 230 for Ga(III) was determined to be 0.38 mol/L. The loaded gallium can be complete stripped by distilled water. A process was established for the selective recovery of Ga(III), by which the purity of the gallium product reached 94% with a yield of 89.5%
... It is worth mentioning that the Ga-bearing host minerals are quite scarce, consequently a large amount of research has been done on the potential Ga resources. Unfortunately, few efficient investigations have been conducted to extract Ga from the BRM, except a recent report from Abdulvaliyev et al. (2015). The researchers treated red mud by using Bayer-hydrogarnet process. ...
... Extraction of Al, Si, and Ti was around 30-50%. Abdulvaliyev et al. [16] found that recovery from red mud by autoclave leaching was 98.5% Na 2 O, 65.3% Al 2 O 3 , 55.5% Ga, and 65.8% V 2 O 5 . Gladyshev et al. [17] investigated the recovery of vanadium and gallium from solids waste by-products of the Bayer process. ...
Article
In this study, the statistical optimization of the leaching parameters of aluminum hydroxide extraction from bauxite waste (red mud) was investigated. The extraction parameters were solid-to-liquid ratio, base concentration, reaction temperature, leaching time, and stirring speed. Optimum experimental conditions were carried out by the Taguchi method. A higher dissolution rate was found to give better performance characteristics. The most important parameter was determined using the statistical analysis of variance. © 2017 American Institute of Chemical Engineers Environ Prog, 2017
... The metal concentration was analyzed by inductively coupled plasma-mass spectrometry (ICP-MS 7'500cx, Agilent Technologies, Basel, Switzerland). The following isotopes were analyzed: 27 Al, 45 Sc, 44 Ca, 47 Ti, 51 V, 53 Cr, 56 172 Yb and 175 Lu. The dwell time was set to 0.3 s per isotope and the argon plasma was operated at 1570 W with an argon flow of 15 L min −1 . ...
Article
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BACKGROUND Red mud is a by-product of alumina extraction from bauxite by the Bayer process produced in the billion tons scale worldwide. Typically it is regarded as waste, but may potentially be a valuable resource of critical raw materials (CRM). In the present study both conventional extracting agents (mineral acids) and small molecular weight complexing agents (organic acids) were evaluated regarding their efficiency to extract CRM such as rare earth elements (REEs) from red mud. On a molar base, highest extraction efficiencies for REEs were achieved using HCl compared to the other acids investigated. Consequently, an experimental design approach was used to determine optimal conditions for CRM extraction using HCl. Instead of maximizing the extraction of a number of selected metals, the maximal economic potential as the sum of all metals (total metal extracted × economic value of the respective metal) was chosen as the application relevant response variable. Four explanatory variables (i.e. HCl concentration, contact time, temperature and slurry concentration) were used. RESULTS Optimal conditions maximizing the economic potential were predicted for 5.60 M HCl, 24 h contact time, 73.4 °C, and 100 g L-1 slurry concentration. Indeed, experimentally determined economic potential corresponded well (96 % of predicted) to the predictions, allowing a maximum recovery of 40.95 ± 0.90 US $ t-1. CONCLUSION Though the studied red muds were relatively low in CRM concentrations, the systematic approach developed here allows straightforward transfer to other red muds, harnessing the potential of the latter as important secondary source for CRM.
... It is well known that the aluminium extraction of Bayer process is conducted by the digestion of bauxite with substantial hot sodium hydroxide solution. Given the generation of desilication products (DSP) mainly presented as sodalite or cancrinite with chemical formula of Na 6 [Al 6 Si 6 O 24 ]·Na 2 X·nH 2 O (X = CO 3 2− , SO 4 2− , 2Cl − , 2OH − or 2NO 3 − ), the losing of sodium hydroxide will accumulate in the red mud during the alumina extraction process (Abdulvaliyev et al., 2015;Zhang et al., 2011). Moreover, this behaviour will limit its application, especially using as iron-making materials, since the low melting point alkali metals circulating in the blast furnace and eroding the lining (Liu and Li, 2015). ...
Article
Red mud cannot be directly employed as the raw material of iron-making and construction materials for the existence of sodium element. The effects of cooling methods of furnace, air, water and liquid nitrogen on roasted red mud for recovering Na+ with water leaching were investigated through the analyses of TG-DTA, QXRD, FTIR, SEM, etc. The faster cooling methods we used, the better leaching performance would be obtained. Liquid nitrogen cooling sample therefore displayed the best leaching result with concentration of 1202 mg·L− 1 Na+ at the first leaching stage (~ 25 wt.% total sodium recovery). Part of cancrinite known as desilication products transformed into NaCaHSiO4 and nepheline after the roasting process. In the fast cooling red muds, the new generation of Na2Ca(CO3)2 could dissolve directly into water; the increase of Ca(OH)2 concentration to ~ 4.8 wt.% was beneficial for the dissolution of cancrinite and NaCaHSiO4 during the leaching process; amorphous phase increasing from ~ 4.1 to ~ 13.5 wt.% made sodium be more easily leached out from sodium-containing amorphous phase than the same crystalline phase; fluey flakes or plate-shape particles weakened the aggregation behaviour; the increase of specific surface area from 1.898 to 2.177 m2·cm− 3 leaded to the contact area increasing between particles and leachant, implying that sodium could be more easily leached out from the fast cooling samples.
... The understanding and control of the transformation of silicon minerals in the extractive metallurgy processes are significant issues (Queneau and Berthold, 1986). As an example, in the Bayer process for Al 2 O 3 production, silicon reacts with alumina and soda to precipitate as insoluble sodium alumina silicate (e.g., sodalite), which is then discharged as red mud causing serious caustic and alumina losses (Abdulvaliyev et al., 2015;Liu and Li, 2015;Smith, 2009). Silicon also causes severe scale formation, which leads to less effective heat transfer (Zheng et al., 1997). ...
Article
This paper provides an overview of methods used to recover gallium from Bayer liquors, highlights and analyzes shortcomings of the current state of research, and predicts the direction of recovery processes in the future. Currently, techniques for recovering gallium from Bayer liquor can be classified as resin ion exchange, solvent extraction, precipitation, and electrochemical. Compared with other recovery methods, the precipitation method is inexpensive but suffers from disadvantages regarding the relatively complex procedures and poor recovery results. Electrochemical methods do not change the solution composition but suffer from low electrolysis efficiency and high mercury content. Solvent extraction methods are simple to operate but complex to separate effectively because of low gallium concentrations. The resin ion exchange method has become the primary method of gallium recovery from Bayer liquor due to its simple operation, high recovery efficiency, and low contamination. Recently, researchers have discovered more efficient methods for recovering gallium based on resin ion exchange: impregnated resin methods and ion blotting. The impregnated resin method combines high adsorption efficiency with extractant selectivity but still suffers from extractant loss problems. Ion impregnation has the advantage of specific adsorption of target ions in complex systems, and its preparation process is improving, which will be a new research hotspot in the future.
Chapter
In recent years, gallium has garnered significant attention in the semiconductor industry, which constitutes over 80% of the total demand. Gallium is widely dispersed in the Earth’s crust, while only two distinct deposits of this precious metal have been discovered—Gallite (CuGaS2) and Soehngeite (Ga(OH)3). Based on the current investigation, it is estimated that approximately 90% of gallium is extracted from the aluminum industry. Therefore, it is imperative for us to explore the synergistic extraction of aluminum and gallium from bauxite, which has been extensively studied by numerous researchers. This paper introduces the trend of gallium in the smelting process of bauxite, summarizing a comprehensive overview of the latest trends in the extraction method of gallium from the bauxite process such as ion exchange method, extraction method, fractional precipitation method, and electrolysis, comparing the advantages and disadvantages of each extraction method, which will guide the efficient extraction of valuable components from bauxite.
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Vanadium is a critical metal that has been widely used in a broad variety of applications with almost no metal substitutes. However, the limited availability of its (vanadium) primary resources has raised concerns of supply security. In view of the criticality, recycling vanadium from secondary resources has been identified as a vital supply alternative. This article thus presents a comprehensive overview of metallurgical processes used in the recycling of vanadium from a variety of secondary resources, including spent HDS catalyst, spent SCR catalyst, fly ash, red mud, Bayer’s sludge, alloy scrap, tailings, etc. First, the physicochemical characteristics of these secondary resources are emphasized. Understanding the characteristics of vanadium-bearing secondary resources is important as it determines the recycling route. The metallurgical recycling processes of vanadium, which include aqueous- and thermal processes are discussed in depth, along with the theoretical backgrounds and fundamentals of each process. Also discussed are the industrial-scale processes and trend in research and development (R&D) for the respective secondary resources. Besides highlighting the status of recycling processes, the article also provides prospective directions for such resources.
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By-products from the non-ferrous industry are an environmental problem; however, their economic value is high if utilized elsewhere. For example, by-products that contain alkaline compounds can potentially sequestrate CO2 through the mineral carbonation process. This review discusses the potential of these by-products for CO2 reduction through mineral carbonation. The main by-products that are discussed are red mud from the alumina/aluminum industry and metallurgical slag from the copper, zinc, lead, and ferronickel industries. This review summarizes the CO2 equivalent emissions generated by non-ferrous industries and various data about by-products from non-ferrous industries, such as their production quantities, mineralogy, and chemical composition. In terms of production quantities, by-products of non-ferrous industries are often more abundant than the main products (metals). In terms of mineralogy, by-products from the non-ferrous industry are silicate minerals. Nevertheless, non-ferrous industrial by-products have a relatively high content of alkaline compounds, which makes them potential feedstock for mineral carbonation. Theoretically, considering their maximum sequestration capacities (based on their oxide compositions and estimated masses), these by-products could be used in mineral carbonation to reduce CO2 emissions. In addition, this review attempts to identify the difficulties encountered during the use of by-products from non-ferrous industries for mineral carbonation. This review estimated that the total CO2 emissions from the non-ferrous industries could be reduced by up to 9–25%. This study will serve as an important reference, guiding future studies related to the mineral carbonation of by-products from non-ferrous industries. Graphical abstract
Article
The disposal of red mud (RM), a waste material generated by the aluminum industry, remains a global environmental concern because of its high alkalinity and smaller particle size, which have the potential to pollute air, soil, and water. Recently, efforts have been made to develop a strategy for reusing industrial byproducts, such as RM, and turning waste into value-added products. The use of RM as (i) a supplementary cementitious material for construction and building materials, such as cement, concrete, bricks, ceramics, and geopolymers, and (ii) a catalyst is discussed in this review. Furthermore, the physical, chemical, mineralogical, structural, and thermal properties of RM, as well as its environmental impact, are also discussed in this review. It is possible to conclude that using RM in catalysis, cement, and construction industries is the most efficient way to recycle this byproduct on a large scale. However, the low cementitious properties of RM can be attributed to a reduction in the fresh and mechanical properties of composites incorporating RM. On the other hand, RM can be used as an efficient active catalyst to synthesize organic molecules and reduce air pollution, which not only makes use of solid waste but also lowers the price of the catalyst. The review provides basic information on the characterization of RM and its suitability in various applications, paving the way for more advanced research on the sustainable disposal of RM waste. Future research perspectives on the utilization of RM are also addressed.
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Red mud and phosphogypsum are staple solid wastes, with considerably large annual emissions. Improving their comprehensive utilization is the key to addressing the large accretion of both red mud and phosphogypsum. They have great utilization potential and can be collectively modified to expand the utilization field and increase the utilization rate. Thus, based on the characteristics of red mud and phosphogypsum, this study summarizes the current status of their coutilization in the fields of building materials, agriculture, environmental protection, and transportation. The development of technologies for the bulk consumption and coproduction of high value-added products is an important direction for the coutilization of red mud and phosphogypsum.
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Red mud (RM) is a solid waste generated during the process of alumina production. RM has already posed a serious environmental threat with the development of the alumina refining industry. The comprehensive utilization of RM has attracted much attention due to its large-scale generation and harmful nature. This paper introduces the characteristics and state of RM and summarizes the relevant research on the comprehensive utilization of RM. The results show that comprehensive utilization of RM is mainly focused on the preparation of building materials, the extraction of valuable metals, catalyst synthesis and environmental protection. Besides, the article discusses the existing problems while utilizing RM. Prospects and suggestions for different utilization methods of RM are proposed.
Conference Paper
Sorption leaching of scandium from red mud was investigated using succinic acid as the leaching agent. The experiments were carried out by mixing red mud with a solution of succinic acid. Various resins and conditions were used to increase the degree of scandium extraction. The highest degree of extraction of Sc was 42 %.
Article
Red mud is an industrial slurry waste that is produced as a byproduct of the Bayer process for alumina. The waste is generated in large quantities, up to a ratio of 2:1 against the valued product alumina. Red mud exhibits many chemical and physical properties that categorize it as a hazardous material. Due to the addition of sodium hydroxide in processing, the pH is typically at values close to 13. Small particle size discourages separation from water for disposal, so drying red mud happens over many years. The pH of red mud can be reduced with inexpensive reagents. Carbon dioxide is a greenhouse gas that is finding a great deal of research into potential sinks to reduce the footprint on the atmosphere. Combining carbon dioxide with red mud can effectively reduce the pH while also providing a sink for the greenhouse gas. Carbon dioxide is able to reduce the pH of red mud from 13 to 10 over long periods of time. Red mud can be utilized to produce a variety of value-added products. Most red muds around the world contain a large quantity of iron, titanium, aluminum, and rare earth elements. One method of removing the iron is through the iron nugget process which reduces iron and removes impurities in a single step. The iron nugget process is able to produce blast furnace quality pig iron (over 90% iron purity) with the addition of a carbonate flux material. Rare earth elements are concentrated in the slags from the iron nugget process and can be removed with acid leaches. The current view of red mud as a waste material is misleading. The proposed work will investigate methods to reduce the hazardous nature of red mud by reducing the pH and also remove valuable minerals. This will effectively give value to the waste product while simultaneously reducing the overall amount of red mud waste that needs to be disposed.
Conference Paper
Leaching scandium from red mud using succinic acid as a leaching agent was investigated. The experimentswere carried out by mixing red mud with a solution of succinic acid. To improve scandium extraction rate, various methods of red mud processing were performed: preliminarygrinding, microwave heating, temperaturetreatment. The highest degree of extraction of Sc was 45 %.
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The article provides the fundamental possibility of the associated extraction of Rare Earth Metals during carbonate conversion of phosphogypsum and red muds. There are the isotherms of solubility of carbonates, phosphates and hydroxides of europium, neodymium, holmium, cerium, and ytterbium obtained in carbonate solutions. By changing the carbonation conditions, Rare Earth Elements are transferred to a carbonate solution in the form of water-soluble complexes. Then they can be recovered by precipitation. Also, there were found the optimum conditions with the maximum degree of recovery into the solution.
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Red mud is generated at a rate of up to 175.5 million tons per year. The global stockpile of red mud is near 4 billion tons. This material is hazardous with pH values from 11 to 13. Reduction of this waste is critical. Current industry practices for disposal of red mud involve different stockpiling techniques on valuable land area or disposing into critical bodies of water. This review studies processes which can reduce the negative environmental impact of red mud in an economic way. For instance, neutralization of red mud with CO2 can decrease the pH from 12.5 to 7. Treatment of red mud by this method lessens the negative environmental impact and prepares it for further processing for utilization. The current utilization rate of red mud is very low, only about 3 million tons per year are used as an additive for cement and construction. Red mud contains a large quantity of valuable minerals that can be extracted to both reduce the amount of red mud and provide value to the waste. This review investigates novel methods for treating red mud and extracting minerals like iron, titanium, and rare earth elements using a variety of smelting, direct reduction, and leaching processes. For example, the iron nugget process is a single step method to reduce iron oxides to metallic iron and separate them from red mud. Iron nuggets produced from red mud have an iron grade above 90%, which is comparable to pig iron generated by the blast furnace.
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Gallium (indium)-containing dust as a hazardous waste generated from light-emitting diode (LED) epitaxial wafer manufacturing attracts worldwide attention because of both resources and environmental importance. Oxidative roasting combined with acidic leaching is frequently utilized to recover the corresponding metals from such dust while the recovery rate is usually low due to the rather inert physicochemical properties of gallium compounds. Simultaneously, the selectivity of leaching is low, which results in complex separation or purification is required in order to obtain the required product, e.g. metallic gallium, Ga(OH)3. In this research, it is demonstrated that the selectivity of leaching can be achieved via properly controlling the physicochemical properties of the leaching solution and the leaching conditions. The leaching rate of gallium can reach 90.01 % through optimizing the effects of different parameters, including leaching reagent concentration, solid-to-liquid ratio, reaction temperature, reaction time and rotation rate, which is about 16 % higher than the conventional method. Moreover, the corresponding leaching mechanisms and kinetics were also evaluated and the apparent activation energy of the reaction is determined as 24.33 kJ/mol. Without further purification, 99.8 % of gallium and 99.1 % of indium can be further recovered as Ga(OH)3 and In(OH)3 from the leaching solutions, respectively. In the whole process, the effective recycling rates of gallium and indium are 89.83% and 92.42 %, respectively. This study provides bases for developing an effective recycling process of such waste with high recovery rate, advanced selectivity and low environmental impacts.
Article
The extraction of Al from Inner Mongolia (China) fly ash by HCl leaching produced a kind of solid waste called red mud (CRM). This red mud contained a great deal of gallium (Ga 2 O 3 , 0.305 wt%) and thus it was a very valuable Ga resource. In this work, an easy hydrothermal alkaline leaching method was developed to extract Ga from CRM. This method mainly solved the separation of Ga and Fe, because they existed in CRM in the form of Ga(OH) 3 and Fe(OH) 3 , and the Fe(OH) 3 in CRM had a strong coating effect on Ga(OH) 3 . In this method, Fe(OH) 3 was converted to Fe 2 O 3 in hydrothermal environment with small specific surface area, which weakened the coating for Ga(OH) 3 and accelerated the leaching reaction between Ga(OH) 3 and NaOH. The influencing factors on the leaching rate of Ga were discussed and the optimal Ga leaching conditions were determined as NaOH concentration of 20 wt%, leaching temperature of 120 °C, leaching time of 12 h, filling degree of 50%, reactor rotating state, and liquid-to-solid ratio of 5 mL/g. The leaching rate of 91.4% was obtained for Ga from CRM at the optimal conditions and the Ga 2 O 3 concentration in leaching solution reached 73.44 mg/L. Fe was not detected in leaching solution using hydrothermal alkaline leaching method and the main component of the leaching residue was α-Fe 2 O 3 with small (average size 3.62 μm) and uniform particle size.
Article
The paper provides an overview of the methods used for processing of red mud to extract rare earth elements (REEs). Red mud is a toxic and highly alkaline waste. Several methods have been adopted and being practiced all over the world for the processing of red mud. Complex processing of red mud is cost-effective since red mud contains iron, aluminum, titanium, calcium, rare earth metals etc. It has been observed that the acid leaching of red mud can almost completely recover the rare earth elements in the solution with various individual techniques and also a combination of them. Therefore, the choice of extraction method depends on the form in which the element occurs in the solution. However, relatively low concentrations of rare earth in the solution and significant amount of impurities increase the cost of getting the final commercial products. To ensure the cost-effectiveness of the process involving rare earth’s extraction from red mud, it is necessary to increase their content by several times. This article presents the various studies that have been carried out in these aspects and the possibility of making this resource a sustainable one for REE extraction with a special focus on scandium replenishment.
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Deposits of bauxite ores near aluminum smelters often possess an excessively high percentage of silica. Development of such high-silica ores would be beneficial to alumina producers. Therefore, unique industrial and operational experience in the field of high-silica bauxite processing was gained at the Russian National Aluminium-Magnesium Institute, St. Petersburg, pilot plant with the consecutive extraction of silica and alumina from low-grade ores. This article describes the chemistry, processing-unit operations, and results obtained from this process.
Article
In this study, recovery of vanadium and gallium from solids waste by-products (vanadium sludge and electrofilter dust of calcination plant) of Bayer process was investigated. An efficient purification process wasdevelopedbased on the removal of impurities such as phosphate by water leaching, neutralisation using CO2-enriched air and addition of aluminate solution. Recovery of V2O5 from the purified solution via the precipitation of ammonium metavanadate, its conversion into polyvanadate by the addition of ammonium sulphate and sulphuric acid, respectively, and then the ignition of the latter at 560°C was demonstrated. Effects of various parameters on the purification and precipitation processes were shown. A treatment process involving sintering and two-stage of carbonisation was also demonstrated to produce a Ga-rich precipitate. A gallate solution suitable for electrolysis of Ga was also shown to be prepared from this precipitate. A complete flowsheet was proposed for the treatment of vanadium sludge and electrofilter dust.
Article
Leach solutions and wastes of Bayer process are important resources for metals such as aluminum and vanadium. Despite the fact that vanadium cake is precipitated and removed in the Seydisehir Eti Aluminum Facility (Turkey), it cannot be used due to low metal content and impurities it contains. Within the scope of this study, research and development of environmentally acceptable, technically sound and low-cost chemical leaching and recovery methods were conducted for the recovery of vanadium from the by-product cake of the Bayer process. In the conducted studies, a sample of vanadium cake was used after its detailed characterization. Roasting tests were performed in order to remove the arsenic in the vanadium cake; however, it was found that roasting was not effective in removing the arsenic from the cake. The performance of different reagents were examined in chemical leaching tests (H2O and H2SO4 leaching, H2SO4 leaching with the addition of NaSO3, and NH4F); in the H2SO4 leaching tests performed with the addition of Na2SO3, the concentration of the reagents and the effect of temperature on the efficiency of vanadium recovery (max. 93.09%) were determined with the full factorial experimental design method, the outcomes were evaluated with ANOVA (variance analysis) method, and empirical models were formed. In lab and semi-pilot scale leaching tests, vanadium recoveries were 96.34% and 94.76% respectively. Vanadium was precipitated with NaOH and FeSO4 and almost all vanadium (95.8%) was obtained as Fe3(VO4)2. Cost analysis and economic evaluation have shown the economic feasibility of the leaching and recovery processes proposed.
Article
The article reviews the cathodic process of gallium ion reduction in alkaline solutions. The solution composition influence on the gallium anion reduction kinetics was analyzed by measuring the polarization curves on a dropping mercury electrode. Itwas found that the cathodic process rate is proportional to the specific adsorption of background cations in the sequence Na+ b K+ b Li+ b Cs+ b La3+. A higher rate of reduction of gallium anion present in alkaline solution of lithiumcation is a result of participation of thewatermolecules fromthe hydration shell of Li+ as a proton donor. In the presence of polyvalent lanthanum cations in alkaline solution, the gallium anion reduction rate increases sharply. This is related to a shift in the ƒÕ1-potential and participation of hydrated cations La(H2O)3 + n. The presence of surface-active agents,which have no proton.donor properties, in the solution, complicates the reduction reaction. Certain patterns of themechanism of the galliumion discharge reaction in alkaline solutions allowqualifying it as the second group of anions, and the slowstage of the reduction reaction comes down to simultaneous transfer of an electron and proton to the discharging anion. The estimated charge of the discharging gallium anion, which is equal to .0.24 in the transition state of the reaction, is indicative of formation of associates with background electrolyte cations [Me+ c GaO2], [Me+ c GaO(OH)2] by gallate anions in alkaline solutions („‚„N 12).
Article
World reserves of bauxite include vast quantities of ore which at present are sub-economic due to high levels of reactive silica that cause expensive loss of caustic soda during Bayer processing. As the economic reserves of high grade ores diminish, attention is turning to how these lower grade ores may be processed at reasonable cost. This paper presents a review of existing and potential processes from the open literature that have been proposed for high silica bauxites. The processes have been divided into three strategies for reducing soda loss. These are (i) reduce the input of reactive silica into the process (ii) modify the process to produce a low soda residue and (iii) recover caustic soda by re-processing residue. For each of the processes considered, a description of the principle is given along with the current status and any hurdles (economic, environmental etc) to implementation.For each strategy the review identifies the most promising processes for future consideration.
Red mud processing methods. Republic of Kazakhstan Innovation Patent
  • R A Abdulvaliev
  • S V Gladyshev
  • K O Beisembekovaet
Abdulvaliev, R.A.,Gladyshev, S.V.,Beisembekovaet, K.O., et al. 2012a. Red mud processing methods. Republic of Kazakhstan Innovation Patent, No. 25940.
Aluminate solution processing methods. Republic of Kazakhstan Innovation Patent
  • R A Abdulvaliev
  • S V Gladyshev
  • E A Tastanov
Abdulvaliev, R.A., Gladyshev, S.V.,Tastanov, E.A., et al. 2012b. Aluminate solution processing methods. Republic of Kazakhstan Innovation Patent, No. 25870.
Method of red mud hydrogarnet processing. Republic of Kazakhstan Innovation Patent
  • N S Bekturganov
  • L A Myltykbayeva
  • E A Tastanov
Bekturganov, N. S., Myltykbayeva, L.A.,Tastanov, E.A., et al. 2013c. Method of red mud hydrogarnet processing. Republic of Kazakhstan Innovation Patent, No. 27264.