Baeyer's process is used to leach Red Bauxite, which has Fe2O3 as the chief impurity. Serpeck's process, on the other hand, is used to leach White Bauxite, which has Silica as main impurity. Both are efficient for their respective ores. But Baeyer's process is more frequently used, as Bauxite, more often than not, is also a source of Gallium ...
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Fig. 2 illustrated the main process of extracting alumina from bauxite by Bayer process and the alkali sources of Bayer bauxite residue. Table 3, Table 4 summarized the main elements and mineralogical compositions of different types of bauxite, as well as the Bayer process parameters applicable to them (Ruys, 2019). It can be concluded that the ...
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Bauxite Al 2 O 2 O; Corundum Al 2 O 3; Cryolite Na 3 AlF 6; Metallurgy of Aluminium. Aluminium is mostly extracted from its bauxite ore. Dressing of Ore. The ore is mechanically crushed and pulverized. Concentration of ore. The bauxite ore contains ferric oxide and silica as impurities.
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Gardannes's Bayer Plant has been modified to process Boké bauxite with a double digestion. ... Bayer process. Higher concentration of spent liquor will bring about higher productivity in ...
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During the electrolysis process, the potential of the cathode relative to the reference electrode was measured as a function of the current at different concentrations of solid (100300 g L −1) and suspension temperatures (95120 °C).
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The bauxite slurry typically has lower caustic concentration liquor as the bauxite is received with some humidity that acts to dilute the liquor which mixes with it at the start of the process. Thus, the step to single stream digestion not only provides an extra heat sink to improve energy efficiency, it also reduces the heater tube caustic ...
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This dissolves aluminium oxide present in bauxite due to the formation of sodium aluminate, (N a A l O 2 ). A l 2 O 2 . H 2 O + 2 N a O H → 2 N a A l O 2 + 3 H 2 O. Since, N a O H a strong reducing agent, it is used in Bayer's process.
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JOM The problem that sulfur causes in alumina production using the Bayer process can be eliminated by adding sodium nitrate, ... Padilla et al. reported that highsulfur bauxite generally refers to the usual bauxite with a sulfur concentration of more than %. 3 The main sulfur minerals in bauxite are pyrite (FeS 2) and its isoforms ...
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ALUMINA FROM BAUXITE: THE BAYER PROCESS. Bauxite, the principal ore used for aluminum smelting, is named after Les Baux, Provence, the village where the first deposits were discovered. Bauxite contains hydrated alumina equivalent to as much as 4060% Al 2 O 3, and is free of the other siliceous materials leached out over time. However it ...
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In this process, the bauxite ore is first crushed and then it is leached by heating with hot concentrated caustic soda (NaOH) solution under high pressure for 2 to 8 hrs at 140 to 150 °C in a tank called a digester. Aluminium oxide, being amphoteric in nature, dissolves in an aqueous NaOH solution, forming watersoluble sodium aluminate.
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The first step is to heat the bauxite ore to temperatures of 200°c along with a sodium hydroxide solution. This will convert the aluminium oxide to a solution of sodium aluminate. The silica will dissolve itself in the process. The chemical equation is. Al 2 O 3 + 2 NaOH → 2 NaAlO 2 + H 2 O.
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Bauxite residue is the byproduct of alumina production and is generated in the Bayer process when bauxite is digested in hot NaOH under elevated temperature and pressure. ... H 2 C 2 O 4 concentration, contact time and temperature had the most pronounced effect on the extracted Ga (ranging from to mg/kg while leaving the other factors ...
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• The purification of bauxite using Bayer's process. • The electrolytic reduction of anhydrous Al 2 O 3 by Hall and Herault's process. • The last step is the purification of impure aluminium by Hoope's process . In Baeyer's process, impure bauxite is converted into pure alumina. The conversion process involves mainly three reactions:
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The slurry from desilication is mixed with NaOH (P13/MX101) up to concentration of 10%, ... The Bayer process is used for refining bauxite to smelting grade alumina (Al 2 O 3), the precursor to ...
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During the processing of bauxite to alumina in the Bayer process, gallium accumulates in the sodium hydroxide liquor. From this it can be extracted by a variety of methods. The most recent is the use of ionexchange resin. Achievable extraction efficiencies critically depend on the original concentration in the feed bauxite.
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The Bayer's process of alumina extraction involves digestion of bauxite with caustic soda at temperatures ranging from 100 to 250 °C, depending on the form of alumina in the bauxite, gibbsitic, boehmitic or diasporic. ... Concentration of bauxite fines via gravity concentration. Rem. Revista la de Minas 62(3), 277281 (2009 ...
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temperature, retention time, free caustic concentration and molar ratio of solution. Based on the experimental data, the calculation models of raw material consumption for different bauxites were established. Under the same basic raw material price, lowtemperature Bayer process was suitable for treating Bauxite1 and Bauxite3.
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The Bayer process is a chemical process for refining aluminium hydroxide, Al(OH) 3 from bauxite; this aluminium hydroxide is subsequently calcined to produce alumina, Al 2 O 3 . The basis of the ...
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Bayer process is about the production of alumina through the refining of aluminum ore (bauxite). The red mud is insoluble slurry waste that contains different types of oxides. Tremendous amount of this slurry is disposed every year (Marwaha et al., 2018 ).
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Aluminium manufacture is accomplished in two phases: the Bayer process of refining bauxite ore to obtain aluminium oxide (which is carried out at AAL), and the HallHeroult process of smelting the ... The maximum concentration of alumina dissolved in the caustic, known as the ratio (as Al 2 O 3 /Na 2 CO 3), occurs in digestion, while the
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3. concentration on silica concentration in the liquor at various residence time is shown below Caustic Concentration of Liquor Higher the caustic concentration faster will be the dissolution of reactive silica from bauxite in the liquor. But at the same time high concentration of caustic liquor will have a higher equilibrium concentration of the silica lowering the desilication rate. 2. ...
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Bauxite is the major ore for aluminum production, and mainly consists of aluminum hydroxides and oxidehydroxides, iron oxides and oxidehydroxides, clay minerals, silicon dioxide and titanium dioxide, often in various polymorphic mineral phases. 7,8 The concentration of gallium in bauxite ranges from below 10 ppm to over 800 ppm, with an ...
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The aim of this work was to achieve an understanding of the distribution of selected bauxite trace elements (gallium (Ga), vanadium (V), arsenic (As), chromium (Cr), rare earth elements (REEs), scandium (Sc)) in the Bayer process. The assessment was designed as a case study in an alumina plant in operation to provide an overview of the trace elements behaviour in an actual industrial setup.
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Alumina is extracted from bauxite by the Bayer process. The waste slurry generated in this process is called red mud and its solid fraction is called bauxite residue. About 12 metric tonnes of bauxite residue is generated for each tonne of alumina produced ( Kumar et al., 2006 ). The global annual generation of bauxite residue is around 120 ...
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While some oxalate enters the Bayer process with bauxite as oxalic acid adsorbed on various minerals, the majority is created by the oxidation and pyrolysis of bauxite organics under Bayer digestion conditions. The rate of its formation in digestion is principally related to the bauxite organic carbon concentration and composition, and to the ...
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The Bayer process is used for producing alumina (Al 2 O 3) from bauxite process was developed and patented by Karl Josef Bayer in 1887 [], which led to a dramatic reduction in the cost of aluminium process involves the following operations: mining, dissolution of the alumina at elevated temperatures, the addition of flocculants, precipitation of pure gibbsite, regeneration of ...
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Bayer's Process of Concentration of Bauxite: This process is applied when bauxite contains more Fe 2 O 3 am less SiO 2. This finely ground calcined ore is digested with 45% NaOH solution in an autoclave under 80 lbs pressure at 150°C for ~ 8 hours. When Al 2 O 3 and SiO 2 go into solution as NaAlO 2 and Na 2 iO 3 respectively. The hot ...
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