Kinetics of Iron Extraction from Coal Fly Ash by Hydrochloric Acid Leaching

Valeev, Dmitry; Михайлова, А. Б.; Atmadzhidi, Alexandra

doi:10.3390/met8070533

Cited by 31 publications

(40 citation statements)

References 36 publications

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“…Further, the recovery of silicate from the silicate material is done by acidic treatment. However, fly ash has several acid-soluble elements such as Na, K, P, Mg, Ca, and Fe [18,179], which can be present in the obtained silicate in a minute quantity [20].…”

Section: Silica Extraction From Fly Ash By Chemical Methodsmentioning

confidence: 99%

Advances in Methods for Recovery of Ferrous, Alumina, and Silica Nanoparticles from Fly Ash Waste

Yadav

Fulekar

2020

Ceramics

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Fly ash or coal fly ash causes major global pollution in the form of solid waste and is classified as a “hazardous waste”, which is a by-product of thermal power plants produced during electricity production. Si, Al, Fe Ca, and Mg alone form more than 85% of the chemical compounds and glasses of most fly ashes. Fly ash has a chemical composition of 70–90%, as well as glasses of ferrous, alumina, silica, and CaO. Therefore, fly ash could act as a reliable and alternative source for ferrous, alumina, and silica. The ferrous fractions can be recovered by a simple magnetic separation method, while alumina and silica can be extracted by chemical or biological approaches. Alumina extraction is possible using both alkali- and acid-based methods, while silica is extracted by strong alkali, such as NaOH. Chemical extraction has a higher yield than the biological approaches, but the bio-based approaches are more environmentally friendly. Fly ash can also be used for the synthesis of zeolites by NaOH treatment of variable types, as fly ash is rich in alumino-silicates. The present review work deals with the recent advances in the field of the recovery and synthesis of ferrous, alumina, and silica micro and nanoparticles from fly ash.

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Section: Silica Extraction From Fly Ash By Chemical Methodsmentioning

confidence: 99%

Advances in Methods for Recovery of Ferrous, Alumina, and Silica Nanoparticles from Fly Ash Waste

Yadav

Fulekar

2020

Ceramics

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“…There were three types of particles: spheres, agglomerates of irregular shape, and porous structures. In previous research, it was shown that spheres consists of alumosilicates and magnetite crystals are located on its surface [26,27]. Agglomerates of irregular shape consist only of alumosilicates.…”

Section: Dry Magnetic Separationmentioning

confidence: 98%

Magnetite and Carbon Extraction from Coal Fly Ash Using Magnetic Separation and Flotation Methods

et al. 2019

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In this study, enrichment methods for coal fly ash (CFA) from Omsk thermal power station No. 4 (TPS-4) were investigated. The magnetite and unburned carbon concentrates were obtained by magnetic separation and flotation methods. The wet magnetic separation used in the study increased the magnetite content in the magnetic fraction from 10.48 to 12.72 wt % compared to dry magnetic separation. The XRD analysis showed that the magnetic fraction primarily consists of magnetite, mullite, and quartz. The SEM analysis demonstrated that magnetite is located primarily on the surface of alumosilicate spheres and has three types of shape: dendritic structures, hexagonal bulk agglomerates, and star-like structures. For the flotation tests, a low-price diesel was used as the collector. It was found that, if CFA particles of 40–71 µm are used, ~99% of unburned carbon can be recovered. It was also found by SEM that, if CFA particles of 71–100 µm are used, alumosilicates on a carbon surface prevent complete interaction of diesel with carbon particles and decrease thereby carbon recovery to 83%.

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“…The diffraction pattern of the NMF material was similar to that of CFA, containing mainly quartz and mullite as well as minor magnetite diffraction peaks. The presence of Fe oxide mineral phases (magnetite and hematite) was observed in the MF material, together with quartz and minor mullite diffraction peaks [44,45,58]. During the magnetic separation process, most of the Fe-containing mineral phases were removed from the bulk of the CFA to yield the NMF material.…”

Section: Mineralogical Composition Of the Magnetic And Nonmagnetic Fraction Of Cfamentioning

confidence: 99%

The Behaviour of Rare Earth Elements from South African Coal Fly Ash during Enrichment Processes: Wet, Magnetic Separation and Zeolitisation

et al. 2021

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Rare earth elements (REEs) are essential raw materials in a variety of industries including clean energy technologies such as electric vehicles and wind turbines. This places an ever-increasing demand on global rare earth element production. Coal fly ash (CFA) possesses appreciable levels of REEs. CFA, a waste by-product of coal combustion, is therefore a readily available source of REEs that does not require mining. CFA valorisation to zeolites has been achieved via various synthesis pathways. This study aimed to evaluate one such pathway by monitoring how REEs partition during CFA processing by the wet, magnetic separation process and zeolitisation. South African CFA was subjected to wet, magnetic separation and subsequent zeolitisation of the nonmagnetic fraction (NMF); solid products were characterised by XRD, SEM, XRF and LA-ICP-MS. The wet, magnetic separation process resulted in the partitioning of a specific set of transition metals (such as Fe, Mn, Cr, V, Ni, Zn, Cu, Co and Mo) into the magnetic fraction (MF) of CFA, while REEs partitioned into the NMF with a total REE content of 530.2 ppm; thus, the matrix elements of CFA were extracted with ease. Zeolitisation resulted in a solid zeolite product (hydroxysodalite) with a total REE content of 537.6 ppm. The process of zeolitisation also resulted in the selective enrichment of Ce (259.1 ppm) into the solid zeolite product (hydroxysodalite), while other REEs were largely partitioned into the liquid phase. CFA valorisation by wet, magnetic separation and zeolitisation therefore allowed for the partitioning of REEs into various extraction products while recovering the matrix elements of CFA such as Fe, Si and Al. The findings of this study highlight the geopolitical importance of REEs in terms of the development of alternative processes for REE recovery from waste and alternative sources, which may potentially give countries that employ and develop the technology a key advantage in the production of REEs for the global market.

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Kinetics of Iron Extraction from Coal Fly Ash by Hydrochloric Acid Leaching

Cited by 31 publications

References 36 publications

Advances in Methods for Recovery of Ferrous, Alumina, and Silica Nanoparticles from Fly Ash Waste

Advances in Methods for Recovery of Ferrous, Alumina, and Silica Nanoparticles from Fly Ash Waste

Magnetite and Carbon Extraction from Coal Fly Ash Using Magnetic Separation and Flotation Methods

The Behaviour of Rare Earth Elements from South African Coal Fly Ash during Enrichment Processes: Wet, Magnetic Separation and Zeolitisation

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