There are a number of alkaline, acid, and thermal methods of refining bauxite, clay, or other ores to obtain alumina. Acid and electrothermal processes generally are either too expensive or do not produce alumina of sufficient purity for commercial use. A process that involves treatment of ore with lime and soda is used in China and Russia.
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Sodium hydroxide is added to bauxite ore during purification of bauxite. Bauxite is reacted with a conc. solution of NaOH under pressure for 2 hrs as a first step in obtaining Al 2 O 3. The impurities present in bauxite mainly Fe 2 O 3 and SiO 2 remain unaffected with conc. NaOH as impurities are not amphoteric. Bauxite, being amphoteric reacts ...
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The aluminum industry is quite resource intensive. Bauxite is the only ore commercially used for extracting aluminum metal. The complete value chain for aluminum production is depicted in Figure, Figure, which shows the raw materials needed for the metal ore is processed to produce alumina by the Bayer process.
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By the Bayer Process, the bauxite is purified. The ore is first combined with a hot, condensed sodium hydroxide solution. Aluminium and silicon oxides, but not other impurities such as iron oxides, can be dissolved by NaOH, which remains insoluble. By filtration, the insoluble materials are removed.
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Bayer's method for the extraction of Alumina: ∙ Conversion of impure bauxite to sodium aluminate; Bauxite in the powdered form is added to conc. sodium hydroxide and then heated in a closed vessel at 433 K and 5−6 bar pressure for 6 −8 hours. The aluminium oxide in bauxite is converted to sodium aluminate which is soluble in water.
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The aluminium compound in bauxite is aluminium oxide and the main impurity is iron (III) oxide, Aluminium is obtained by the electrolysis of aluminium oxide dissolved in cryolite. (i) Name the process used for the purification of bauxite. (ii) Write the equation for the action of heat on aluminium hydroxide.
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To generate aluminium oxide, bauxite is purified, a white powder from which aluminium can be extracted.
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Among environmental hot spots all over the world are the tailings of RM, generated during the digestion of bauxite ore with sodium hydroxide by Bayer process for the extraction of alumina. The term 'red mud' is used as a synonym for 'bauxite residue'. The residue generated is usually highly alkaline with pH about [1, 2].
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Step 4 Digestion process. In the digestion process, the slurry is heated to 270℃ to form a sodium aluminate supersaturated solution or "pregnant liquor". A hot caustic soda (NaOH) solution can dissolve the aluminiumbearing minerals in the bauxite. There are two types of bauxite: gibbsite, böhmite and diaspore.
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(a) When bauxite is treated with sodium hydroxide solution, what happens to (i) the aluminium oxide (ii) the iron (III) oxide (b) (i) Name the process used for the purification of bauxite. (ii) Write the equation for the action of heat on aluminium hydroxide. (c) (i) Write the formula of cryolite.
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Serpeck's process is the process of converting bauxite into aluminum nitride. This process is generally used when silica is present in the bauxite ore. Therefore, Hall's process, Baeyer's process and Serpeck's process are the various processes used for the purification of bauxite. Hence, options A,B and C are correct. Separation ...
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A process for producing alumina from bauxite is described in which bauxite is treated with an alkali to form a mixture comprising a solution of aluminumcontaining ions and alumina trihydrate is precipitated from the solution. The process comprises treatment of the solution before or after the precipitation step with a layered double hydroxide in order to remove impurities from the solution by ...
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Therefore, iron oxide and silica are the two impurities of the bauxite ore. Note: The extraction of the bauxite can be done by the process such as Bayer's process and Hall Heroult's process. In Bayer's process, the production of aluminium oxide takes place after which in Hall Heroult's process it pure aluminium is extracted by the smelting ...
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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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Purification of Bauxite ore. 1. Name of the purification process. It is the Baeyer's process that is used for the purification of impure oxides of Aluminum. 2. Chemical equations involved in Baeyer's process. The main impurities found in the impure oxide of Aluminum Al 2 O 3. 2 H 2 O are Iron(III) oxide, Fe 2 O 3 and Silica SiO 2.
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Leaching is used for the purification of Bauxite ore. Leaching is a process that is used in extractive metallurgy. In this process, the ore is treated with chemicals to convert the valuable metals within into soluble salts while impurity remains insoluble. Key Points. The leaching of aluminium oxide from bauxite is called Baeyer's process.
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Bauxite processing wastes (red mud) 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 ). Aluminum, silicon, iron, and calcium oxides are ...
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During the digestion process of the Bayer method, lithium and gallium in bauxite will enter into the sodium aluminate solution (Tang et al. 2020; Xu et al. 2018), which will return to the digestion process for recycling after the precipitation of aluminum hydroxide from the decomposition of crystal to a large amount of red mud discharge, most of the lithium and gallium in the ...
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As the minerals are weathered they gradually breakdown into various forms of hydrated aluminum oxide, Al 2 O 3 .xH 2 O, known as bauxite. The bauxite is purified by the Bayer Process. First the ore is mixed with a hot concentrated solution of sodium hydroxide. The NaOH will dissolve the oxides of aluminum and silicon but not other impurities ...
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The alumina is then smelted using the energyintensive HallHeroult process to produce aluminium metal by electrolytic reduction in a molten bath of ... accounting for only 60% of the bauxite Ore Reserve from 2002 (1700 Mt). Both Ore Reserves and production have gradually risen over the last 15 years. Ore Reserves of bauxite increased from 1700 ...
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1) Purification of Bauxite. The purification of bauxite ore can be done by Baeyer's process. a) The powdered bauxite ore is treated with hot concentrated (45%) solution of sodium hydroxide at 473523 K and 35 36 bar pressure. b) In this process, alumina (Al 2 O 3) dissolves forming sodium aluminate. This process is called leaching.
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(ii) Sodium hydroxide is added to bauxite ore during purification of bauxite. Bauxite is reacted with a conc. solution of NaOH under pressure for 2 hrs as a first step in obtaining Al 2 O 3. The impurities present in bauxite mainly Fe 2 O 3 and SiO 2 remain unaffected with conc. NaOH as impurities are not amphoteric. Bauxite, being amphoteric ...
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The Bayer process is the first stage in the extraction of aluminium. It involves the purification of bauxite to obtain pure anhydrous aluminium oxide, also k...
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The ore is first purified and then the metal is extracted from it by electrolytic reduction. (a) Write three balanced equations for the purification of bauxite by Hall's process. (b) Name a chemical used for dissolving aluminium oxide. In which state of subdivision is the chemical used?
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Solution Bayer's process is used for the purification of bauxite Al 2 O 3 · 2 H 2 O. Aluminium is extracted by Bayer's process. The bauxite is powdered and mixed with a concentrated solution of caustic soda NaOH to give sodium meta aluminate and impurities are removed by filtration.
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Q3._____ process is used purification of bauxite ore. A. Froth flotation B. Blast furnace C. Baeyer's Process Answer: C. Solution: Baeyer's Process is mostly used on bauxite ore with ferric oxide as the major contaminant. Because the ore is usually red in colour, it is known as red bauxite. Q4.
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The process dissolves the aluminium component of bauxite ore in sodium hydroxide (caustic soda). Under pressure of 3500 kPa and high tem peratures the chemical reactions are rapid [6] : Gibbsite
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Serpeck's process. This process is used for the purification of bauxite ore containing silica (SiO 2) as the main impurity. The powdered ore is mixed with coke and the mixture is heated at about 1800°C in the presence of Nitrogen gas, when aluminium nitride is formed. Al 2 O 3. 2H 2 O + 3C + N 2 → 2AI N + 3CO+ 2H 2 O
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