Aluminum production is accomplished in two processes: the Bayer process for refining bauxite ore to obtain aluminum oxide, or alumina, and the HallHéroult electrolytic process for smelting the alumina dissolved in cryolite to produce pure aluminum metal. The Bayer process marks the beginning of the modern field of hydrometallurgy.
S. Bhargava M. Hollitt S. Grocott A. Hartshorn D. Akolekar M. Allen. Chemistry, Materials Science. 2004. The Bayer process has been used to refine bauxite ore to alumina for over a century. While implementation of new technologies and an enhanced understanding of process chemistry has yielded..
the alumina production in the simplest and most efficient Bayer process. The proposed technology for processing lowquality gibbsitekaolinite bauxites, with preliminary twostage enrichment, makes it possible to obtain a material suitable for the production of alumina by the simplest and most efficient Bayer method. 2. Materials and Methods
In China, lowgrade diasporic bauxite with an Al 2 O 3 /SiO 2 mass ratio below 8 can be processed by sintering or through a combination of sintering and the Bayer process [12, 13]. But the sintering process and the combined process are comparatively energyintensive and environmentally less friendly, incurring high alumina production costs [ 14 ].
Among environmental hot spots all over the world are the tailings of RM, generated during the digestion of bauxite ore with sodium hydroxide by Bayer process for the extraction of alumina. The term 'red mud' is used as a synonym for 'bauxite residue'. The residue generated is usually highly alkaline with pH about [1, 2].
Bayer method is currently used in 95% of alumina production in the world, which requires higher bauxite grade. [2,3,4,5,6] If the ore with Al/Si ratio less than 7 is treated simply by Bayer method, the lowgrade highsilica bauxite must be desilicated by roastingalkali leaching preprocessing method prior to be used in the Bayer system.
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 ...
Since each refinery, depending on the type of bauxite, operates on unique Bayer process technology [6, 15, 16] to obtain alumina, it has become necessary to review the chemical...
2 Al (OH) 3 → Al 2 O 3 + 3 H 2 O The leftover, 'spent' sodium aluminate solution is then recycled. Apart from improving the economy of the process, recycling accumulates gallium and vanadium impurities in the liquors, so that they can be extracted profitably.
The reaction process, mechanism, and kinetics of the desulfurization of highsulfur bauxite during calcination were investigated using thermal analysisinfrared analysis. A conveyorbed calcination system was used to study the variations in the physical phase, desulfurization rate, and alumina dissipation rate of highsulfur bauxite in the range of 500 °C650 °C. The results show that ...
Step 4 Digestion process. In the digestion process, the slurry is heated to 270℃ to form a sodium aluminate supersaturated solution or "pregnant liquor". A hot caustic soda (NaOH) solution can dissolve the aluminiumbearing minerals in the bauxite. There are two types of bauxite: gibbsite, böhmite and diaspore.
The Bayer process is the main method of alumina production worldwide. ... a concentrate of A/S ratio is achieved for a raw bauxite ore with a A/S ratio. ... ; 1; 3 and 6% of the ...
The main component of bauxite is Al 2 O 3, containing a small amount of Fe 2 O 3, SiO 2, and other impurities. The main objective of bauxite beneficiation is to lower the concentration of reactive silica, and also to increase the alumina content. In addition, bauxite beneficiation can also be used for iron extraction or iron removal.
The Bayer Process is the most economic means of obtaining alumina from bauxite. Other processes for obtaining alumina from metal ores are also in use in some refineries, particularly in China and Russia, although these make up a relatively small percentage of global production. The process stages are: 1. Milling
Red mud, also referred to as bauxite residue, is the largest process waste produced during alumina production from bauxite ore by the Bayer method. Approximately 12 tons of red mud are produced for every ton of alumina produced 1. Global red mud manufacturing is anticipated to be 200 million tons annually.
The Pedersen process could, for example, be used to process bauxite residue from the Bayer process, since the raw material can be considered as a high iron containing ore (Lazou et al., 2021).
However, the hightemperature reduction, smelting and alkaline leaching process is a feasible method to recover iron and alumina from ironrich bauxite and red mud. This chapter intends to provide the reader an overview on comprehensive utilization technology of the lowgrade ironrich bauxite and Bayer red mud sources. Keywords bauxite
Bauxite processing wastes (red mud) 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 ). Aluminum, silicon, iron, and calcium oxides are ...
The industrial production process for alumina from bauxite was developed in 1887 by the chemist KarlJosef Bayer (portrait opposite). It is still used today thanks to important improvements made over time. The bauxite is crushed then mixed with soda at high temperature and under pressure.
Bayer's method for the extraction of Alumina: ∙ Conversion of impure bauxite to sodium aluminate; Bauxite in the powdered form is added to conc. sodium hydroxide and then heated in a closed vessel at 433 K and 5−6 bar pressure for 6 −8 hours. The aluminium oxide in bauxite is converted to sodium aluminate which is soluble in water.
The results of studies on the processing of gibbsitekaolinite bauxite are presented. The developed technology includes preliminary chemical activation and thermal transformation during enrichment to obtain a concentrate suitable for processing by the Bayer method. As a result of the chemical activation of gibbsitekaolinite bauxite in a solution of sodium bicarbonate, a change in the phase ...
This is the process of re4ining alumina from bauxite (aluminum ore containing 3050% of hydrated aluminum oxide) by selective extraction of pure aluminum oxide dissolved in sodium...
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