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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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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The Bayer process, as it has become known, is used for refining bauxite to smelting grade alumina (aluminum oxide), the precursor to aluminium. Typically, depending upon the quality of the ore, between and tonnes of bauxite is required to produce 1 tonne of alumina. The Bayer process is a cyclic one and is often called Bayer cycle.
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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 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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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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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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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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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 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
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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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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 Bayer Process. The Bayer Process, which is used by about 80 active plants worldwide, is the primary method of producing aluminum from bauxite. Bauxite ore is dissolved in sodium hydroxide, or lye, at a high temperature and pressure. Then, the alumina and bauxite ores are separated by washing out the waste (red muds or sands) from the alumina.
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that suggests about 70% of bauxite Ga is digested in the Bayer process, and this part is subsequently precipitated into aluminium hydroxide. About 30% of Ga is separated from the process with bauxite
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If the bauxite mineralogy is known, it is an easy step to calculate Bayer process parameters to obtain a better understanding of bauxite's economic value, leading to more efficient production ...
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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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At the start of the process, the bauxite is finely ground and, with the addition of caustic soda, converted into a viscous suspension (chemists say: digested). The sus pension is pumped through the pipes of a reactor and heated up in stages to approx. 270 °C. The lye dissolves almost specifically as the temperature rises and under pressure.
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At the start of the process, the bauxite is finely ground and, with the addition of caustic soda, converted into a viscous suspension (chemists say: digested). The suspension is pumped through the pipes of a reactor and heated up in stages to approx. 270 °C.
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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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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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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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