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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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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To maintain economic alumina production, a number of investigations have been conducted to try and minimise the impact of silica on the economics of existing processes and to develop new methods for processing high silica bauxite (Smith, 2009).One of the methods is to effectively preconcentrate high silica bauxite or aluminous minerals by the roastleach process (Smith and Xu, 2010, Jiang et ...
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In the Bayer process, bauxite is digested with sodium hydroxide solution at high temperature and pressure producing alumina and generating the waste known as 'red mud' or 'bauxite residue' in large quantity. After the process, the residue which is alkaline in nature has pH of and is disposed of in red mud ponds.
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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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One of the advantages of a tube reactor is that the slurry undergoes turbulent plug flow as the slurry moves ... 2. Wahnsiedler, The Kinetics of Bauxite Digestion in the Bayer Process Light Metals 1985, TMS, Warrendale, 145±182. 3. Lesinski, Sullivan, Method of employing dextrans, Patent USA, Dow
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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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A new step in the Bayer process has been used to recover NaOH and to reduce its content in red mud. After digestion, the residue is separated from the Bayer liquor and goes through press filters, which enables the recovery of NaOH and decreases the moisture content. It is well known that red mud is one of the most important sources of scandium. For this reason, the goal of this work was to ...
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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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• Digestion; • Clarification; • Precipitation; and • Calcination. A simplified process flow diagram of the Bayer process used at the Wagerup refinery is presented in Figure 6. Bauxite Grinding and Slurry Storage Bauxite is ground to less than mm particle size at the refinery, using semiautogenous
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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 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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As shown in Figure 1, the source of energy to the Bayer Process is the Powerhouse. Energy is distributed essentially as steam to Digestion and Evaporation and electrical power to the refinery. The amount of energy required is determined by four interrelated factors: 1. Type of Bauxite. Trihydrate bauxite (low temperature digest or
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1. Introduction At present, imported bauxites are widely used by alumina refineries in China, mainly from Guinea, Australia, Indonesia, Ghana, Vietnam and Brazil.
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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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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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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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One of the alumina industry's main problems is the organic matter in the Bayer liquor during the Bayer Process released in the bauxite digestion process and accumulating in the process.
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The effect of lime on gibbsite bauxite digestion is different from its effect on diaspore bauxite due to its different composition and digestion properties [15, 16]. In one report, gibbsite bauxite was digested by adding 1% lime at 145 °C, achieving a better digestion efficiency of %. However, excessive lime addition will lead to excess ...
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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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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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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 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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1. Introduction. The Bayer process is an industrial method of bauxite pressure digestion in strong sodium hydroxide caustic solutions. As a result, aluminium hydroxide is selectively extracted, crystallized from the process liquor and then calcined to metallurgical grade alumina (Chin, 1988).The current study is performed in association with Aluminium of Greece plant (AoG), which utilizes both ...
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Bayer process liquors are supersaturated not only with alumina but also with contaminants such as silica and oxalate which are derived from digestion of the bauxite ore with caustic liquor; such ...
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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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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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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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From the broadest viewpoint, the Bayer process exists to separate the alumina content of aluminous minerals in bauxite such as gibbsite, boehmite and diaspore from anything which is not.
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Let's contemplate on bauxite residue! A suggested path forward Which path shall we follow? Let's move forward! 1. Get involved (LinkedIn, ResearchGate, your own blog...) 2. Check out our new website and join the team 3. Participate in the coming "Bauxite Residue
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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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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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Compared to typical Bayer digestion with Algoethite containing gibbsitic bauxite as raw material, the red mud yield of reductive Bayer digestion decreases from % to %, and the grade of ...
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The major portions of the impurity enter the Bayer process through bauxite. Beyond the critical levels the impurities alter the kinetics of the process. Among the various impurities, organic carbon is the most prominent one that affects the precipitation operation and the product quality, depending on the level of organic with respect to the ...
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