Stage 2: Alumina production. In the 1890s, Austrian chemist Carl Josef Bayer invented a revolutionary process for extracting alumina from bauxite. Today—over 100 years later—some 90% of ...
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The bauxite ore, Bayer process materials before precipitation, mud residue, and sand residue are therefore of radiological interest, whereas the alumina product is Positional and personal monitoring data from bauxite mines and alumina refineries in Western Australia have been used to assess the abovebackground annual doses for the ...
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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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Both forms can have deleterious effects on Bayer process operations used to produce smelter grade alumina from bauxite ore. Jamaican bauxite which is comprised mainly of gibbsite (Al 2 O 3 ·3H 2 ...
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The Bayer process involves four steps: digestion, clarification, precipitation, and calcination. Read More Other articles where Bayer process is discussed: alumina: .extracted from bauxite through the Bayer process, which was developed for the aluminum industry in 1888.
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1. Milling The bauxite is washed and crushed, reducing the particle size and increasing the available surface area for the digestion stage. Lime and "spent liquor" (caustic soda returned from the precipitation stage) are added at the mills to make a pumpable slurry. 2. Desilication
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Because the aluminum component in bauxite is digested in a 5 N sodium hydroxide solution, the purity of alumina produced by the Bayer process is approximately % with the remainder Na 2 O.
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The current Bayer process focused on alumina extraction without considering the comprehensive utilization of other valuable components, such as iron, and the resulting red mud caused severe ecological and environmental safety risks. This work proposed a clean twostage Bayer digestion technology to obtain ironrich red mud with low Na 2 O content from highiron gibbsitic bauxite processing.
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Precipitation 2. Desilication In the Bayer process the desilication of bauxite is an important step to maintain the alumina quality. It requires conversion of reactive silica of the bauxite into a nonsoluble sodalite complex (Sodium aluminium silicate or sodalite). The desilication can be carried out before digestion or after the digestion ...
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1. Introduction. The Bayer process developed and patented by Karl Joseph Bayer 110 years ago is used for refining bauxite ore into smelting grade alumina (Al 2 O 3).The Bayer process involves the digestion of bauxite in concentrated caustic at high temperatures followed by precipitation, clarification, and calcination to recover the alumina content. 1, 2, 3 The remaining insoluble solids from ...
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The Bayer process is a continuous process which may be separated into four simple steps: hydrothermal digestion, where the bauxite is heated in hot caustic soda solutions to dissolve the aluminium bearing minerals; clarification, where separation of the aluminiumrich solutions and undissolved components of bauxite (bauxite residue) occurs; crys...
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Aluminum Production. Alton T. Tabereaux, Ray D. Peterson, in Treatise on Process Metallurgy: Industrial Processes, 2014 Impact of Different Bauxites on the Bayer Process. The Bayer process is basically used for the extraction of aluminum hydrate from the bauxite ores with the mass ratio of alumina to silica (A/S) above 9. The sinter process is widely used to process the poorgrade ...
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silica minerals in the gibbsite bauxite during the digestion process at high temperatures was also studied. It was determined that the phase transition of aluminogoethite is enhanced at 250 °C. By further raising the temperature and extending the digestion time, aluminogoethite transforms into hematite, from which more alumina can be recovered.
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The soda sintering process is used for materials which are hardly digestible via the Bayer process and requires high temperatures of °C, usually °C[13 17]. It is basically a "dry digestion" of aluminum oxides with soda (Na 2CO 3) and employs the principle of the sodapotash digestion, but in this case without ...
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Bayer Process A process flow diagram of the Bayer process is shown in Exhibit 3. The primary purpose of a Bayer plant is to process bauxite to provide pure alumina for the production of aluminum. All bauxite refineries share five common process steps: (1) ore preparation; (2) bauxite digestion; (3) clarification; (4) aluminum hydroxide precipi ...
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process and the remaining 30 % ending up in bauxite residue, and this can be used as one of the main assumptions for assessing the distribution of Ga in the Bayer process in the absence of
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The Bayer process involves four steps: digestion, clarification, precipitation, and calcination. In the first step, bauxite is ground, slurried with a solution of caustic soda ( sodium hydroxide ), and pumped into large pressure tanks called digesters, where the ore is subjected to steam heat and pressure.
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Lithium is one of the secondary mineral elements occurring in bauxite, where lithium content can reach up to % (as Li 2 O) [1,2,3].During the digestion process, lithium in bauxite is extracted into Bayer liquor, and in the following seed precipitation process, it coprecipitates with alumina hydroxide (ATH), resulting in high lithium content in alumina and, consequently, raising lithium ...
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Effect of thermal conversion gibbsitic bauxite in Bayer digestion Alumina recovery To minimize the inhibitory effect caused by Algoethite on gibbsitic bauxite digestion, the lowtemperature roasting process was used to pretreat bauxite before Bayer digestion.
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Abstract. In the Bayer process, used for the production of alumina from the bauxite ores, there are frequent disturbances and a large number of interacting processes which incorporate considerable ...
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to another one, sodalite to cancrinite. Solid particles (in this case bauxite and/or bauxite residue) can be entrapped in the scale and ... Bayer Digestion and Predigestion Desilication Reactor Design, Proceedings of TMS Conference, ... (To the Chemical Process of Bauxite Digestion. Studies in system of Na2OAl2O3TiO2H2O) Metall, 25 ...
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The Bayer process is the principal method for production of alumina from bauxite worldwide. The modern version of the process (developed in the 1880's) still maintains
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In the Bayer process, bauxite ore is heated in a pressure vessel along with a sodium hydroxide solution (caustic soda) at a temperature of 150 to 200 °C. At these temperatures, the aluminium is dissolved as sodium aluminate (primarily [Al (OH) 4] −) in an extraction process.
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The Bayer process is a chemical process for refining aluminium hydroxide, Al(OH)3from bauxite; this aluminium hydroxide is subsequently calcined to produce alumina, Al2O3.
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1 Citations Part of the Springer Series in Materials Science book series (SSMATERIALS,volume 320) Abstract This chapter aims to illustrate and discuss the inputs and outputs for both water and energy in the context of the Bayer process, highlighting throughout the sections their interconnectedness.
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Beside the processing behaviour of the main constituents of bauxite such as hydrated alumina and silica minerals, the Chapter covers the impact of other constituents, such as titania, iron...
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Different ways for alkaline recovery of aluminum from bauxite residue are considered from the literature and examined in experiments. The advantages and disadvantages of a hightemperature digestion via Bayer process and sodalime sintering process are elaborated and compared. As a hybrid process, bauxite residue undergoes a reductive smelting process with lime addition in an electric arc ...
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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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Very small differences in bauxite hardness or density, mainly through variability in the content of ironcontaining hardcap, can lead to an increased recirculating load. This also leads to a longer residence time, with the possibility of a buildup of a critical size inside the mill.
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Bauxite residue, a potential secondary source of CRM, can contain considerable amounts of strategically important metals depending on its geologic origin and processing [6, 7]. 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.
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