Hall's process for leaching of alumina from bauxite: (1) Bauxite ore and sodium carbonate are fused toghether to convert aluminium oxide into soluble sodium metaaluminate. The insoluble residue contains the impurities of silica and iron oxide. The fused mass is treated with water.
K. V. Chudnenko Russian Academy of Sciences Abstract A process of dissolution Severoonezhsk deposit boehmitekaolinite bauxite by hydrochloric acid, as well as the processes that occur during...
The leaching process with dilute HNO 3 was performed at pilot scale and optimized for the extraction of scandium from bauxite residue ( OchsenkühnPetropoulou et al., 2002 ). Xue et al. (2010) found that at a reaction temperature of 90 °C and an L/S ratio of 3:1, over 80% of the scandium in bauxite residue could be leached by H 2 SO 4.
More than 90% of the world's commercial manufacture of alumina is obtained by hydrochemical sodium hydroxide extraction of bauxite through the conventional Bayer process. The Bayer process is, however, associated with the generation of bauxite residue which cannot easily be disposed due to its high alkaline content, which can degrade the ...
The Bayer process is used worldwide for the alumina production. This process involves the alkaline leaching of bauxite to extract Al, followed by the precipitation of Al(OH) 3 to recycle the solution [1,2,3].The leaching process results in the formation of a solid residue, commonly referred to as a bauxite residue, which consists of iron minerals, hydrous aluminosilicates, which are formed ...
Alkali process primarily contains sintering and hydrochemical process. In the sintering process, aluminacontaining materials are mixed with limestone and sintered, transforming silica into dicalcium silicate and alumina into calcium aluminate. Then, alumina can be separated from silica efficiently in followed sodium carbonate leaching process .
Bauxite reaction residue (BRR) produced from the polyaluminum chloride (PAC) coagulant industry is a solid acidic waste that is harmful to environment. A low temperature synthesis route to convert the waste into water glass was reported. Silica dissolution process was systematically studied, including the thermodynamic analysis and the influence of calcium and aluminum on the leaching of ...
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 ...
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 ...
The Bayer process is used for refining bauxite to smelting grade alumina, the precursor to aluminum. Typically, depending upon the quality of the ore, between and tonnes of bauxite is required to produce 1 ton of alumina. The Bayer process involves the digestion of crushed bauxite in the concentrated sodium hydroxide (caustic) solution at
Aluminum dross samples were found to approximately contain 75wt% Al2O3 and 12wt% SiO2. An acid dissolution process was used to recover the alumina value from the dross. The effects of various parameters,, temperature, acid concentration, and leaching time, on the extraction of alumina were studied to optimize the dissolution process.
Introduction. Bauxite is the major ore for aluminum production. 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).
After smelting to remove iron from bauxite residue, alumina can be recovered from the ironfree slag by an acid leaching process. The aluminum recovery rates from the slag by most common inorganic acids can be listed as H 3 PO 4 >H 2 SO 4 >HCl>HNO 3. Since sulphuric acid is a diprotic acid, it donates more protons to the solution than both ...
As a hybrid process, bauxite residue undergoes a reductive smelting process with lime addition in an electric arc furnace in order to generate aluminaenriched slag. This slag is subsequently treated with highpressure caustic leaching at moderated (200300 g/l) and high (572762 g/l) sodium hydroxide concentrations.
The Bayer process holds an exclusive status for alumina extraction, but a massive amount of caustic "red mud" waste is generated. In this work, three oxalate reagents: potassium hydrogen oxalate (KHC 2 O 4), potassium tetraoxalate (KHC 2 O 4 ·H 2 C 2 O 4), and oxalic acid (H 2 C 2 O 4) were investigated for the Al and Fe extraction process from NIST SRM 600 AustralianDarling range ...
Bauxite residue, known as red mud, is a byproduct of alumina production using the Bayer process. Currently, its total global storage amounts to over billion tons, including about 600 million tons in Russia. The total global storage of red mud occupies large areas, leading to environmental damage and increasing environmental risks. Moreover, it contains a significant amount of sodium ...
The bulk of bauxite production is used as feed for the manufacture of alumina via a wet chemical caustic leach process known as the Bayer process . The majority of the alumina produced from this refining process is smelted using the HallHéroult process to produce aluminum metal by electrolytic reduction in a molten bath of natural or ...
Literature leaning towards Bayer process efficiency often targets leaching conditions in Bayer digestion and selectivity of aluminum precipitation species for activated alumina recovery, and from the byproduct valorisation, the sintering of bauxite residues for the recovery of aluminum and sodium [25,26,27,28]. The scope of this work will be ...
Abstract The recovery of major components of bauxite residue by carbothermic reduction at °C and subsequent slag leaching in a Na3CO3(aq) solution is studied. Iron recovers primarily to pigiron and lime is added to tune the calcium aluminate slags towards the highly leachable mayenite phase. The concentration of aluminum in the leachate correlates well with the occurrence of ...
In the water leaching process, Na Al Si O 4 was dissolved while the amorphous phase underwent some transformations to form the water leaching residue, ... When highsilica bauxite is used as a feedstock for alumina production, more bauxite residue is discharged compared to processing highgrade bauxite. 30 At present, ...
The application of bauxite enrichment in the Bayer process before leaching for bauxites from Guinea and Sierra Leone is due to the loss of alumina or alkali in the red mud.
In the leaching process, various leaching temperatures and time, lime addition amounts and Na 2 O concentrations were studied, and the alumina dissolution ratio and the iron content in the red mud were also investigated to determine the better dissolution conditions. Typically, a certain amount of bauxite powder and lime were mixed with a ...
DOI: /materproc Corpus ID: ; The Efficient Use of Sulfuric Acid in Bauxite Residue Leaching article{Toli2023TheEU, title={The Efficient Use of Sulfuric Acid in Bauxite Residue Leaching}, author={Aikaterini Toli and Dimitrios Kotsanis and Maria Psoma and Danai Marinos and Panagiotis Davris and Efthymios Balomenos and Dimitrios Panias}, journal={RawMat 2023}, year ...
Red mud (RM) is a waste generated during bauxite processing for alumina production. The most common method for bauxite processing is the Bayer process, where raw material is digested under high pressure by NaOH to obtain a pregnant sodium aluminate solution [].During highpressure leaching, nonsoluble elements such as iron, titanium, and refractory or precipitated during washing step aluminum ...
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 ...
To prevent this, a desilication process to reduce the amount of silicon in solution is conducted prior to precipitating hydrated alumina. In the Bayer process, bauxite ores are pressure leached at a high temperature (100250 °C) using sodium hydroxide solution. The leachate solution is then cooled and seeded to precipitate alumina hydrates.
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