To test this hypothesis, a set of digestion experiments were conducted using gibbsite, one of the major minerals in bauxite. Gibbsite was digested at various temperatures (50, 75, and 95 °C) in ...
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
The Bayer process is the principal industrial means of refining bauxite to produce alumina (aluminium oxide) and was developed by Carl Josef, the most important ore of aluminium, contains only 3060% aluminium oxide (Al 2 O 3), the rest being a mixture of silica, various iron oxides, and titanium aluminium oxide must be further purified before it can be refined into ...
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...
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.
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.
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 ...
The alumina extraction and iron minerals' comprehensive utilization of technology that could replace the current Bayer process have not yet been formed. In the current Bayer digestion process, gibbsitic bauxite was digested at a temperature, alkali concentration, and time of 100150 °C, 120190 g/L, and 1090 min, respectively.
% in four bauxite samples, and % in one. Logomerac reported [8] that the bauxite at Titograd (now Podgorica, Montenegro) contained ... (The distribution of elements content in bauxite during the Bayer digestion process) Proceedings of Symposium sur les Bauxites, Oxides at Hydroxides D'Aluminium, Zagreb, 1963, Vol. III., pp. 147 ...
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 ...
The most commonly used methods for aluminium production are the Bayer process and the HallHeroult process. The Bayer process is used to produce alumina (Al 2 O 3) from bauxite and the HallHeroult process is used to produce molten aluminium from the year 1887, Karl Josef Bayer invented a method of extracting aluminium hydroxide from bauxite through Bayer processing.
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 ...
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 ...
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 ...
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.
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.
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.
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.
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 ).
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
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
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 ...
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 ...
Bauxite residues (also known as 'red mud', 'Bayer process tailings' or 'bauxite process tailings') are generated from alumina production where bauxite is digested in hot NaOH solution via the Bayer The production of 1 tonne of alumina generates between 1 and tonnes of bauxite Currently, the yearly global ...
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 ...
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 ...
1. Introduction At present, imported bauxites are widely used by alumina refineries in China, mainly from Guinea, Australia, Indonesia, Ghana, Vietnam and Brazil.
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.
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.
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 ...
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 ...
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.
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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