The Bayer process is the principal industrial means of refining bauxite to produce alumina (aluminium oxide) and was developed by Carl Josef Bayer. Bauxite, 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 dioxide. [1]
The Bayer process is used for refining bauxite to smelting grade alumina (Al 2 O 3), the precursor to aluminium. ... (Na2Ox or K2Ox) increases with an increase in concentration of the counter ion ...
The Bayer process is the principal method for the production of alumina from bauxite worldwide. The modern version of the process (developed in the 1880's) still maintains the key steps of dissolution of aluminarich minerals into hot caustic solution, separation of the insoluble phases, followed by gibbsite precipitation and calcination of the gibbsite to alumina (Al 2 O 3).
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. ... H 2 C 2 O 4 concentration, contact time and temperature had the most pronounced effect on the extracted Ga (ranging from to mg/kg while leaving the other factors ...
Aluminum production from bauxite is achieved with the Bayer process, which is a hydrometallurgical method. However, in the Bayer process, in time, it is possible to encounter problems such as the formation of excessive amounts of red mud in aluminum production, its environmental risks, its requirement of large storage sites, the excessive production of reactants by ores with low silica modulus ...
For the same grade of bauxite ore, using the traditional Bayer process, the theoretical maximum alumina dissolution rate is % and the Na 2 O mass fraction in the slag is about % (A/S = 1 and N/S = in the red mud), while the actual dissolution rate of the Bayer process bauxite ore in this alumina plant is about 70%, which shows ...
Fig. 2 illustrated the main process of extracting alumina from bauxite by Bayer process and the alkali sources of Bayer bauxite residue. Table 3, Table 4 summarized the main elements and mineralogical compositions of different types of bauxite, as well as the Bayer process parameters applicable to them (Ruys, 2019). It can be concluded that the ...
The slurry from desilication is mixed with NaOH (P13/MX101) up to concentration of 10%, ... The Bayer process is used for refining bauxite to smelting grade alumina (Al 2 O 3), the precursor to ...
Li et al. [42] have further proved that the accelerated conversion of goethite and Algoethite by adding 2 g/L glycerol during the Bayer process favored the beneficiation and concentration of iron ...
Crushed bauxite is treated with moderately concentrated sodium hydroxide solution. The concentration, temperature and pressure used depend on the source of the bauxite and exactly what form of aluminum oxide it contains. Temperatures are typically from 140°C to 240°C; pressures can be up to about 35 atmospheres.
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
Alumina is extracted from bauxite by the Bayer process. The waste slurry generated in this process is called red mud and its solid fraction is called bauxite residue. About 12 metric tonnes of bauxite residue is generated for each tonne of alumina produced ( Kumar et al., 2006 ). The global annual generation of bauxite residue is around 120 ...
Bayer's method: In this method, bauxite powder is taken and concentrated (45%) and sodium hydroxide solution is added and then heated in a closed vessel at 433 K temperature and 5 to 6 bars of pressure, for 6 to 8 hours, so that aluminium oxide present in bauxite is converted into sodium aluminate which is soluble in water. In bauxite, in ...
As we go around the circuit, the aluminium concentration is decreased in the Precipitation (or crystallisation) step, and we end up with a "spent" liquor. This spent liquor (now poor in dissolved aluminium) completes the circuit to treat more bauxite. So the crux of the Bayer Process is dissolution of aluminium from its ore in the early part of
Bayer's Process of Concentration of Bauxite: This process is applied when bauxite contains more Fe 2 O 3 am less SiO 2. This finely ground calcined ore is digested with 45% NaOH solution in an autoclave under 80 lbs pressure at 150°C for ~ 8 hours. When Al 2 O 3 and SiO 2 go into solution as NaAlO 2 and Na 2 iO 3 respectively. The hot ...
3. concentration on silica concentration in the liquor at various residence time is shown below Caustic Concentration of Liquor Higher the caustic concentration faster will be the dissolution of reactive silica from bauxite in the liquor. But at the same time high concentration of caustic liquor will have a higher equilibrium concentration of the silica lowering the desilication rate. 2. ...
This paper proposes a novel approach to sulfur removal by adding aluminum in the bayer process of highsulfur bauxite. The effects of aluminum dosage on the concentrations of different valence sulfur in sodium aluminate solution were investigated at length to find that highvalence sulfur (S 2 O 3 2−, SO 3 2−, SO 4 2−) concentration in sodium aluminate solution decreases, but the ...
The concentration of the Bauxite ore into alumina is done by Bayer's process. Alumina is then refined into pure aluminium metal through the HallHéroult electrolytic process. Aluminium is too high in the electrochemical series (reactivity series) to be extracted from its ore using carbon reduction.
The Bayer process is the main method of alumina production worldwide. The use of lowquality bauxites for alumina production results in the formation of a significant amount of technogenic waste—bauxite residue (BR). The Bayer reductive method is one possible way to eliminate BR stockpiling, but it requires highpressure leaching at temperatures higher than 220 °C.
(a) The process for concentration of bauxite ore is Bayer's process (In which an ore of aluminium which is bauxite is heated in a pressure vessel along with a solution of sodium hydroxide also known as caustic soda at a temperature of 150 to {200^o}C .
S 2 2− in high sulfur bauxite undergoes gradual transformation into S 2 O 3 2−, SO 3 2−, and SO 4 2− during the Bayer process, which leads to adverse effects in production . For example, it causes corrosion of steel equipment [ 3, 4 ], an increase in alkali consumption [ 5 ], a reduction in heat transfer efficiency [ 6 ], and affects ...
JOM The problem that sulfur causes in alumina production using the Bayer process can be eliminated by adding sodium nitrate, ... Padilla et al. reported that highsulfur bauxite generally refers to the usual bauxite with a sulfur concentration of more than %. 3 The main sulfur minerals in bauxite are pyrite (FeS 2) and its isoforms ...
The bauxite slurry typically has lower caustic concentration liquor as the bauxite is received with some humidity that acts to dilute the liquor which mixes with it at the start of the process. Thus, the step to single stream digestion not only provides an extra heat sink to improve energy efficiency, it also reduces the heater tube caustic ...
In this process, the bauxite ore is first crushed and then it is leached by heating with hot concentrated caustic soda (NaOH) solution under high pressure for 2 to 8 hrs at 140 to 150 °C in a tank called a digester. Aluminium oxide, being amphoteric in nature, dissolves in an aqueous NaOH solution, forming watersoluble sodium aluminate.
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 bauxite (alumina content ∼5459 wt%) used as the raw material in the Bayer process for the synthesis of alumina was obtained from a mine at Weipa in Queensland, bauxite ores were crushed to a particle size of <10 μm using an attrition mill. Table 1 lists the composition of bauxite supplied from the support company. A 5 N sodium hydroxide solution was used for the ...
Gardannes's Bayer Plant has been modified to process Boké bauxite with a double digestion. ... Bayer process. Higher concentration of spent liquor will bring about higher productivity in ...
Therefore, the aluminum concentration in the liquor is kept below the solubility limit, which is ensured by the high solidtoliquid ratios of 1/6 in case of Bayer process with bauxite residue and sintering and 1/10 in case of aluminaenriched slag leaching. Results and Discussion.
The research on pressure leaching started in 1887. Karl Josef Bayer was the first one who proposed to leaching bauxite with sodium hydroxide solution at a temperature of 413453 K to obtain sodium ...
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