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Article

Acid and Acid-Alkali Treatment Methods of Al-Chloride Solution Obtained by the Leaching of Coal Fly Ash to Produce Sandy Grade Alumina

1
Laboratory of New Metallurgical Processes, A.A. Baikov Institute of Metallurgy and Materials Science, Russian Academy of Sciences, 49, Leninsky Prospect, 119334 Moscow, Russia
2
Scientific Research Centre “Thermochemistry of Materials”, National University of Science & Technology “MISIS”, 4, Leninsky Prospect, 119049 Moscow, Russia
3
Department of Non-ferrous Metals Metallurgy, Ural Federal University named after the first President of Russia B.N. Yeltsin, Yekaterinburg 620002, Russia
4
Laboratory of Crystal Structure Studies, A.A. Baikov Institute of Metallurgy and Materials Science, Russian Academy of Sciences, 49, Leninsky Prospect, 119334 Moscow, Russia
*
Author to whom correspondence should be addressed.
Metals 2020, 10(5), 585; https://doi.org/10.3390/met10050585
Received: 13 April 2020 / Revised: 28 April 2020 / Accepted: 28 April 2020 / Published: 29 April 2020
(This article belongs to the Special Issue Advances in Mineral Processing and Hydrometallurgy)
Sandy grade alumina is a valuable intermediate material that is mainly produced by the Bayer process and used for manufacturing primary metallic aluminum. Coal fly ash is generated in coal-fired power plants as a by-product of coal combustion that consists of submicron ash particles and is considered to be a potentially hazardous technogenic waste. The present paper demonstrates that the Al-chloride solution obtained by leaching coal fly ash can be further processed to obtain sandy grade alumina, which is essentially suitable for metallic aluminum production. The novel process developed in the present study involves the production of amorphous alumina via the calcination of aluminium chloride hexahydrate obtained by salting-out from acid Al-Cl liquor. Following this, alkaline treatment with further Al2O3 dissolution and recrystallization as Al(OH)3 particles is applied, and a final calcination step is employed to obtain sandy grade alumina with minimum impurities. The process does not require high-pressure equipment and reutilizes the alkaline liquor and gibbsite particles from the Bayer process, which allows the sandy grade alumina production costs to be to significantly reduced. The present article also discusses the main technological parameters of the acid treatment and the amounts of major impurities in the sandy grade alumina obtained by the different (acid and acid-alkali) methods. View Full-Text
Keywords: coal fly ash; sandy grade alumina; AlCl3·6H2O; crystallization; salting-out method; gibbsite; precipitation coal fly ash; sandy grade alumina; AlCl3·6H2O; crystallization; salting-out method; gibbsite; precipitation
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MDPI and ACS Style

Valeev, D.; Shoppert, A.; Mikhailova, A.; Kondratiev, A. Acid and Acid-Alkali Treatment Methods of Al-Chloride Solution Obtained by the Leaching of Coal Fly Ash to Produce Sandy Grade Alumina. Metals 2020, 10, 585. https://doi.org/10.3390/met10050585

AMA Style

Valeev D, Shoppert A, Mikhailova A, Kondratiev A. Acid and Acid-Alkali Treatment Methods of Al-Chloride Solution Obtained by the Leaching of Coal Fly Ash to Produce Sandy Grade Alumina. Metals. 2020; 10(5):585. https://doi.org/10.3390/met10050585

Chicago/Turabian Style

Valeev, Dmitry, Andrei Shoppert, Alexandra Mikhailova, and Alex Kondratiev. 2020. "Acid and Acid-Alkali Treatment Methods of Al-Chloride Solution Obtained by the Leaching of Coal Fly Ash to Produce Sandy Grade Alumina" Metals 10, no. 5: 585. https://doi.org/10.3390/met10050585

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