A prospective process for alumina extraction via the co-treatment of coal fly ash and bauxite red mud: Investigation of the process

Guo, Yanxia; Li, Jian; Yan, Kezhou; Cao, Lei; Cheng, Fangqin

doi:10.1016/j.hydromet.2019.04.011

Cited by 39 publications

(8 citation statements)

References 27 publications

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“…Guo et al [62] proposed the preliminary calcination process of a mixture of red mud and fly ash from coal-fired power plants in the presence of sodium carbonate in the temperature range of 600-900 • C for 2 h followed by acid leaching. Leaching of the calcine, which was obtained by roasting at 850 • C the mixture of 100 g of the ash and 106.4 g of red mud, by 6 M HCl solution and boiling for 2 h led, to the dissolution of above 90% of alumina.…”

Section: Direct Acid Digestionmentioning

confidence: 99%

Extraction of Valuable Elements from Red Mud with a Focus on Using Liquid Media—A Review

et al. 2021

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Bauxite residue, known as red mud, is a by-product of alumina production using the Bayer process. Currently, its total global storage amounts to over 4.6 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, which is easily soluble in subsoil water; therefore, a sustainable approach for comprehensive recycling of red mud is necessary. The bauxite residue contains valuable elements, such as aluminum, titanium, and scandium, which can be recovered using liquid media. In recent years, many methods of recovery of these elements from this waste have been proposed. This paper provides a critical review of hydrometallurgical, solvometallurgical, and complex methods for the recovery of valuable components from red mud, namely, aluminum, titanium, sodium, and rare and rare-earth elements. These methods include leaching using alkaline or acid solutions, ionic liquids, and biological organisms, in addition to red mud leaching solutions by extraction and sorption methods. Advantages and disadvantages of these processes in terms of their environmental impact are discussed.

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Section: Direct Acid Digestionmentioning

confidence: 99%

Extraction of Valuable Elements from Red Mud with a Focus on Using Liquid Media—A Review

et al. 2021

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“…Environmental protection and effective use of limited resources are the main problem restricting the development of the aluminum industry. Many researchers are exploring new more efficient aluminum extraction methods [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Extraction of Al from Coarse Al–Si Alloy by The Selective Liquation Method

Wang

Gao

2021

Materials

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A selective liquation process to extract Al from a coarse Al–Si alloy, produced by carbothermal reduction, was investigated on the laboratory scale. The products obtained by selective liquation–vacuum distillation were analyzed by X-ray diffraction, inductively coupled plasma optical emission spectrometry and scanning electron microscopy. During the selective liquation process with the use of zinc as the solvent, the pure aluminum in the coarse Al–Si alloy dissolved in the zinc melt to form an α-solid solution with zinc, and most of the silicon and iron-rich phases and Al–Si–Fe intermetallics precipitated and grew into massive grains that entered into the slag and separated with the Zn–Al alloy melt. However, some fine silicon particles remained in the Zn–Al alloy. Thus, Al–Si alloys conforming to industrial application standards were obtained when the Zn–Al alloys were separated by a distillation process.

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“…Many hydrometallurgical methods of alumina extraction from CFA have been developed to date. They can be divided into alkaline [7][8][9], acidic [10][11][12][13], and roasting (combined pyro-and hydrometallurgical) [14][15][16][17][18][19][20], when the roasting product is leached by water or mineral acids.…”

Section: Introductionmentioning

confidence: 99%

Kinetics Study of Al Extraction from Desilicated Coal Fly Ash by NaOH at Atmospheric Pressure

2021

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The most promising source of alumina in the 21st century is the coal fly ash (CFA) waste of coal-fired thermal plants. The methods of alumina extraction from CFA are often based on the pressure alkaline or acid leaching or preliminary roasting with different additives followed by water leaching. The efficiency of the alumina extraction from CFA under atmospheric pressure leaching is low due to the high content of acid-insoluble alumina phase mullite (3Al2O3·2SiO2). This research for the first time shows the possibility of mullite leaching under atmospheric pressure after preliminary desilication using high liquid to solid ratios (L:S ratio) and Na2O concentration. The analysis of the desilicated CFA (DCFA) chemical and phase composition before and after leaching has been carried out by inductively coupled plasma optical emission spectrometry (ICP-OES) and X-ray diffraction (XRD). The morphology and elemental composition of solid product particles has been carried out by scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). An automated neural network and a shrinking core model (SCM) were used to evaluate experimental data. The Al extraction efficiency from DCFA has been more than 84% at T = 120 °C, leaching time 60 min, the L/S ratio > 20, and concentration of Na2O—400 g L−1. The kinetics analysis by SCM has shown that the surface chemical reaction controls the leaching process rate at T < 110 °C, and, at T > 110 °C after 15 min of leaching, the process is limited by diffusion through the product layer, which can be represented by titanium compounds. According to the SEM-EDX analysis of the solid residue, the magnetite spheres and mullite acicular particles were the main phases that remained after NaOH leaching. The spheric agglomerates of mullite particles with non-porous surface have also been found.

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A prospective process for alumina extraction via the co-treatment of coal fly ash and bauxite red mud: Investigation of the process

Cited by 39 publications

References 27 publications

Extraction of Valuable Elements from Red Mud with a Focus on Using Liquid Media—A Review

Extraction of Valuable Elements from Red Mud with a Focus on Using Liquid Media—A Review

Extraction of Al from Coarse Al–Si Alloy by The Selective Liquation Method

Kinetics Study of Al Extraction from Desilicated Coal Fly Ash by NaOH at Atmospheric Pressure

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