Thermal and Mechanical Activation in Acid Leaching Processes of Non-bauxite Ores Available for Alumina Production—A Review

Barry, Thierno Saidou; Uysal, Turan; Birinci, Mustafa; Erdemoğlu, Murat

doi:10.1007/s42461-018-0025-7

Cited by 27 publications

(14 citation statements)

References 64 publications

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“…Mechanical activation is applied in the following industrial fields: mechanical alloying, preparation of ores, leaching of ores and extractive metallurgy, sintering of materials, manufacture of pigments and paints, manufacture of pharmaceutical and geopolymers products to which new areas of application are constantly being added. [99][100][101][102][103].…”

Section: Fig 1 Phase Transitions Of Alumina Mineralogical Phases [93]mentioning

confidence: 99%

Short review on mechanical activation in non-metallurgical alumina production

Kim¹,

Dobra²,

Isopescu³

et al. 2022

RJEEC

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The terms mechano-chemistry and mechanical activation of solid materials were introduced in chemical literature by Ostwald at the beginning of the XX century. Both terms cover a whole range of interconnected phenomena taking place during the mechanical action on solids or their separate parts participating in chemical reactions, phase transitions, mixing and creating composite materials, alloying and crystal growth in the solid state, deformation and changing physical and thermal properties, all of them at low temperature. The common effects of the mechanical activation on solid material are fracturing and reduction of particle sizes, generation of new reactive surfaces, diffusion of atoms of the reactant phase through the product phase, and quite significantly, accumulating energy in crystalline or amorphous structure (enough twists in atomic and molecular networks, tensions in atomic bond and active sites to trigger the nucleation of new phases). Mechanical activation is very used to produce all clean alumina mineralogical phases with uniform particle size dimensions from nano to macro size. Also, mechanical activation may extend the specific surface of some minerals, enhancing the yields in the solid-liquid extraction process. With adequate precursors, all phase transitions from amorphous to alfa α-Al2O3 can be carried out on the same route as in thermally activated alumina, but some other routes, impossible by thermal activation, might be followed. The difference between the two activation ways is that mechanical activation is made at room temperature.

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Section: Fig 1 Phase Transitions Of Alumina Mineralogical Phases [93]mentioning

confidence: 99%

Short review on mechanical activation in non-metallurgical alumina production

Kim¹,

Dobra²,

Isopescu³

et al. 2022

RJEEC

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“…According to reaction (5), amorphous alumina is dissolved in the liquor to form hydrated sodium aluminate, thereby increasing the supersaturation of the liquor relative to the coarse Al(OH) 3 particles [52]. Next, dissolved alumina in the form of hydrated sodium aluminate precipitates on the surface of Al(OH) 3 via reaction (6). Li et al showed that Al(OH) 3 agglomeration also proceeds during the late stages of the precipitation process [56].…”

Section: Sga Production From Amorphous Aluminamentioning

confidence: 99%

“…A decrease in the bauxite quality and orientation of the main aluminum producers (Russia and China) with regards to their own resources has led to investigations of alternative raw materials for SGA production [3]. In fact, it can be obtained from both natural (kaolin clay [4,5] or pyrophyllite ore [6]) and technogenic (red mud [7], coal fly ash (CFA) [8], and secondary aluminum dross [9,10]) materials. The CFA waste generated from coal-fired power plants is one of the most promising raw materials for SGA production [11], since it does not require preliminary grinding, as in…”

Section: Introductionmentioning

confidence: 99%

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

Valeev

Shoppert

Михайлова

2020

Metals

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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.

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“…Therefore, the acid process has an extensive application prospect in extracting Al from low-grade Al ore. For the acid method, HNO 3 is chosen as the acid medium of coal gangue/fly ash for the following reasons: (1) Fe 2+ can be fully oxidized into Fe 3+ due to the strong oxidizing ability of HNO 3 . So more iron ions are hydrolyzed into hematite at high temperatures, which achieves selective leaching of Al; (2) the scaling problem of the autoclave caused by the formation of CaSO 4 when H 2 SO 4 is used as the medium can be avoided; (3) the decomposition temperature of Al(NO 3 ) 3 ·9H 2 O is only 250 °C, which is far below 1000–1200 °C of AlCl 3 ·6H 2 O and 1350 °C of Al 2 (SO 4 ) 3 ·18H 2 O . Hence the thermolysis of Al(NO 3 ) 3 ·9H 2 O and the regeneration of HNO 3 are bound to greatly reduce the cost of acid recovery Al from coal gangue/fly ash; and (4) our team has successfully applied HNO 3 pressure leaching technology to the treatment of laterite ore, realizing the recovery of HNO 3 and the enrichment of Fe in slag. − Eighty percent of Al in coal fly ash , and 95% of Al in coal gangue were leached out via HNO 3 pressurization technology by our team, but 6% of Fe in coal fly ash and 2% of Fe in coal gangue still inevitably entered the leach liquor.…”

Section: Introductionmentioning

confidence: 99%

Phase Diagram of the Al(NO₃)₃–Fe(NO₃)₃–H₂O(−HNO₃) System and Its Application in the Separation of Al³⁺ and Fe³⁺

Shi

Shao

et al. 2023

J. Chem. Eng. Data

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An original technology named HNO3 pressure leaching has been proposed by our team to leach Al from coal gangue and fly ash. Although the preliminary separation of Al and Fe had been achieved during leaching, a small amount of Fe impurity was still unavoidably dissolved into the leach liquor. To obtain pure Al2O3 during subsequent pyrolysis, it is imperative to synchronously remove Fe3+ during the crystallization of Al(NO3)3·9H2O. Herein, the phase equilibria of the Al(NO3)3–Fe(NO3)3–H2O(−HNO3) system at 25–40 °C and 0–8.12 mol kg–1 of HNO3 molality were investigated. The results indicated that the ternary system was a simple cosaturated type consisting of an immutable point, two univariate curves, and two crystallization regions. Notably, the solubility and crystallization region of Al(NO3)3·9H2O were barely impacted by acidity, while the opposite was true for Fe(NO3)3·9H2O. This finding was instructive for the crystallization of Fe(NO3)3·9H2O from the liquor with high Fe and low Al. Moreover, a high crystallization yield could be obtained at low temperatures. Finally, an appropriate crystallization procedure was provided. This study is expected to provide basic data and theoretical support for the crystallization and separation of mixed nitrates containing Al and Fe.

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Thermal and Mechanical Activation in Acid Leaching Processes of Non-bauxite Ores Available for Alumina Production—A Review

Cited by 27 publications

References 64 publications

Short review on mechanical activation in non-metallurgical alumina production

Short review on mechanical activation in non-metallurgical alumina production

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

Phase Diagram of the Al(NO₃)₃–Fe(NO₃)₃–H₂O(−HNO₃) System and Its Application in the Separation of Al³⁺ and Fe³⁺

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Thermal and Mechanical Activation in Acid Leaching Processes of Non-bauxite Ores Available for Alumina Production—A Review

Cited by 27 publications

References 64 publications

Short review on mechanical activation in non-metallurgical alumina production

Short review on mechanical activation in non-metallurgical alumina production

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

Phase Diagram of the Al(NO3)3–Fe(NO3)3–H2O(−HNO3) System and Its Application in the Separation of Al3+ and Fe3+

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Product

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Phase Diagram of the Al(NO₃)₃–Fe(NO₃)₃–H₂O(−HNO₃) System and Its Application in the Separation of Al³⁺ and Fe³⁺