Austria 1888: Karl Josef Bayer first discovered the Bayer process (digesting crushed bauxite in strong sodium hydroxide solution at temperature up to 240oC. ... Dressing or Concentration of the Bauxite ore by Hall's method . The dressing is the process of extracting a metal from an ore in which gangue is removed and the ore is prepared for ...
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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 reason for the same is that the higher bauxite solids concentration in the slurry would yield more desilication product seed, which could in turn accelerate the desilication process. Nowadays with the current technological advances, it is possible to pump and agitate slurry with solids concentration up to 800 1000 gpl.
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Bauxite residues from alumina production. Aluminium production consists of two key stages: The first is alumina refining (Bayer process), which involves the generation of alumina from bauxite ore; the second stage is aluminium smelting (HallHéroult), the process of transforming alumina into Most of the world's alumina is produced using the Bayer process, although minor volumes ...
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Step 1: Mining bauxite. Four tons of bauxite produce one ton of aluminum—enough to make the cans for more than 60,000 soft drinks. Bauxite is formed over millions of years by chemical weathering of rocks containing aluminum silicates, producing an ore rich in aluminum oxide. Today, bauxite is mined primarily in Africa, Australia and the ...
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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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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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The Bayer process for alumina production generates more than 160 million tons of bauxite residue annually. The current global stockpiles of bauxite residue have reached more than 4 billion tons ...
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(1) Bayer's process is used to obtain pure aluminium oxide from bauxite. (2) Bauxite is then concentrated by chemical separation. Bauxite contains impurities like iron oxide (Fe(2)O(3)) and silica (SiO(2)). (3) Bauxite ore is powdered and heated with sodium hydroxide under high pressure for 2 to 8 hours at 140^()C in the digester. The aluminium oxide being amphoteric in nature present in ...
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Describe Bayer process for concentration of bauxite
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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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Bayer process, trace elements, bauxite residue, cerium, yttrium. 1. Introduction. The presence and importance of many trace elements found in bauxites has been acknowledged decades ago, as well as their transfer into bauxite residue or product alumina during the Bayer process [1 3]. When entering the process, the significance of trace ...
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Describe Bayer's Process. Doubtnut App Get 50 Lakh+ video solutions better than Google
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Prior to the Bayer process bauxite is crushed and ground in mills to fine particles (max. size "/). A hot solution of the recycled sodium hydroxide (caustic soda, NaOH) is then added to the ground ore forming a bauxite slurry, which is stored in holding tanks and then pumped to the further processing stage. Refined aluminum oxide (Al ...
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How is alumina separated from bauxite by Bayer's process? Doubtnut App Get 50 Lakh+ video solutions better than Google Install Now. Ask doubt. Courses. IITJEE. Class 11; Class 12; Dropper; NEET. Class 11; Class 12; Dropper; UP Board. ... Describe Bayer's process for concentration of bauxite ore. 12:56.
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To validate the superior digestion property of sodium aluminosilicate generated via an actual process, the Bayer digestion of an Al 2 O 3rich material derived from reductive roasting of bauxite and comprising Na Al Si O 4 was conducted; the relative digestion ratio of Al 2 O 3 attained 90% at 200°C.
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Lime is an essential reagent required in various process steps of the Bayer process, in which bauxite ore is converted into alumina (Whittington et al. 1997), as illustrated in Fig. is used for improving conversion of goethite to hematite and dissolution of boehmite and diaspore during digestion; control of liquor impurities such as silica, oxalate, titanium and phosphorous; minimising ...
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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.
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The Bayer process is used for refining bauxite to smelting grade alumina (Al 2 O 3), the precursor to aluminium. ... (Na2Ox or K2Ox) increases with an increase in concentration of the counter ion ...
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Red mud is a slimy caustic residue generated from alumina refining of bauxite ores. During the alumina extraction process, about 35 %40 % of the bauxite ores go into the residue as highly alkaline red mud slurry (pH ) which contains 15 %40 % of solid phase in volume [1, 2].Depending on the quality of bauxite ores, producing 1 t alumina basically generates t red mud [].
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The Bayer process is used for refining bauxite to smelting grade alumina, the precursor to aluminum. Typically, depending upon the quality of the ore, between and tonnes of bauxite is required to produce 1 ton of alumina. The Bayer process involves the digestion of crushed bauxite in the concentrated sodium hydroxide (caustic) solution at
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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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Aluminum production from bauxite is achieved with the Bayer process, which is a hydrometallurgical method. However, in the Bayer process, in time, it is possible to encounter problems such as the formation of excessive amounts of red mud in aluminum production, its environmental risks, its requirement of large storage sites, the excessive production of reactants by ores with low silica modulus ...
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Bauxite residue is generated during the Bayer process of alumina recovery from bauxite ore. The chemical compositions of bauxite residue are associated with the alumina process and the raw bauxite ores. The broad ranges of contents are reflected in both the 68 main components and more than 50 trace elements.
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Explain why a concentrated basic solution is used in the Bayer process. A strong base is used to dissolve aluminum oxide. Skill Describe the chemistry of the Bayer process for the extraction of alumina. Yes, it is. Skill Explain the chemical property base on electromotive potentials. A thin layer of aluminum oxide protects it from oxidation.
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In the Bayer process for the production of alumina, aluminium is leached from the bauxite ore using NaOH at elevated temperatures and pressures [1]. The residue of the Bayer process is called bauxite residue (BR) or red mud (RM), because of its red ferric oxide color. Bauxite residue consists mainly of ferric oxide, aluminium (hydr)oxides ...
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the dissolved metal as the "back" end. This is the essence of the continuous Bayer Process used by the industry today. Caustic liquor (a strong caustic soda solution) is the medium moving around the circuit. When bauxite is added, the aluminium dissolves and a "green" (or pregnant) liquor richer in aluminium is formed.
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The Bayer process, the production of pure aluminium oxide hydrate (or more chemically formulated aluminium hydroxide) from bauxite, and the calcination process, the production of pure aluminium oxide from the aluminium oxide hydrate. However, these two processes are often combined in books and the media and referred to as "the Bayer ...
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The Bayer Process was patented in 1888 in Germany by the Austrian chemist, Karl Joseph Bayer [].The simple chemistry of the process is that the hydrated forms of aluminum in bauxite, readily dissolve in heated caustic (NaOH) solutions (the DIGESTION step, see Chap. 4).The advantage is that nearly all of the minerals in bauxite containing other metallic ions do not dissolve and so can be ...
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A material supplier from Belgium would like to produce limestone powder for his custome...
India is rich in various mineral resources and it is an important mineral processing market
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