Composition and Morphology of Fly Ash Cenospheres Produced from the Combustion of Kuznetsk Coal

Fomenko, Elena V.; Anshits, N. N.; Solovyov, Leonid A.; Mikhaylova, Olga A.; Anshits, A. G.

doi:10.1021/ef400754c

Cited by 84 publications

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“…It can mean that the formation of cenospheres in the aforementioned cases occur from the same mineral form of initial coals. According to our previous study, 13,14 the aluminosilicate composition of narrow fractions of the cenospheres with an The transformation of kaolinite particles during a rapid heating for 0.2−2.0 s at temperatures of 900−1250°C, followed by rapid cooling, leads to the formation of foam particles. 43 The porous structure formed at the stage of the dehydroxylation of kaolinite is retained due to a rapid cooling of the particles.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Characterization of Fly Ash Cenospheres Produced from the Combustion of Ekibastuz Coal

et al. 2015

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The relationship between the chemical composition and shell structure of cenospheres with a low bulk density of 0.40−0.45 g/cm 3 and a high Al 2 O 3 content of 33−38 wt % has been systematically studied. It was established that the composition of the narrow fractions of cenospheres can be described by the general regression equation SiO 2 /Al 2 O 3 = 4.34 − 0.08[Al 2 O 3 ] with the correlation coefficient of r = −0.99. The phase composition includes the glass phase (57−73 wt %), mullite (25−40 wt %), and quartz (1.2−2.5 wt %). An increase in the Al 2 O 3 content leads to an increase in the size of particles and the porosity of their shells. In the obtained fractions of cenospheres, there are two types of globules: spherical globules with a singlering structure and foamy globules with a network structure. It is established that the composition of individual particles with a network structure localized in the range of the Al 2 O 3 content from 43 wt % to 51 wt % and can be described by the regression equation SiO 2 /Al 2 O 3 = 2.71 − 0.04[Al 2 O 3 ] with the correlation coefficient of r = −0.97. The framework of these particles permeated by mullite microcrystallites and coated with a nanoscale surface film. The structure-forming mineral precursor of these particles is kaolinite. The gross composition of the shell of individual globules with a single-ring structure localized in the range of the Al 2 O 3 content from 26 wt % to 42 wt % and can be described by the general regression equation SiO 2 /Al 2 O 3 = 4.71− 0.09[Al 2 O 3 ] with the correlation coefficient of r = −0.98. The outer and inner surfaces of the shell are covered by large and small in-plane localized mullite crystals hidden by the nanoscale film. The spherical shape and their crystalline framework are formed from the illite melt with inclusions of products of the thermal conversion of other mineral forms. ■ INTRODUCTIONIn the process of generating power from coal, large quantities of coal combustion products (CCPs) are produced. According to the various estimates, combustion of coal in the Russia alone generates ∼25 million tons of CCPs per year but utilization rate does not exceed 15%. 1 The complex composition of CCPs, including the fly ash, has proven to be a barrier to its bulk utilization in many fields. Extraction of concentrates of microspherical components with specific characteristics from fly ashes of variable composition provides wider opportunities for the multicomponent use of fly ashes produced from coal combustion. 2,3 The unique properties of cenospheres, namely, their low density, sphericity of particles, and high strength and nontoxicity, make them useful for a variety of fields of applications. Thus, concentrates of cenospheres are used as fillers of lightweight composite materials, such as concretes, 4,5 polymers and resins, 6−8 and metal alloys. 9,10 Also, they are been studied for the production of ceramic composite foams with different properties. 11,12 In recent years, new functional materials have been developed based on a d...

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Section: ■ Experimental Sectionmentioning

confidence: 99%

Characterization of Fly Ash Cenospheres Produced from the Combustion of Ekibastuz Coal

et al. 2015

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“…The pulverized combustion of coals also involves the formation of low density aluminosilicate microspheres, called -cenospheres‖ (Fomenko, Anshits et al 2013). Most of these spherical particles are larger than 10 µm, but submicronic spherules are also emitted.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Fine and Ultrafine Particles in the Vicinity of Industrial Activities: A Review

Riffault

Arndt

Marris

et al. 2015

Critical Reviews in Environmental Science and Technology

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ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT2 This review synthesizes the existing knowledge on the characteristics of PM 2.5 at sites under the direct influence of industrial emissions, with a specific focus on their morphology, size distributions and chemical composition. Results from on-line and off-line analytical techniques indicate a high temporal and spatial variability of mass size distribution and chemical composition depending on the type of industrial processes, the sampling distances and frequencies, and the meteorological conditions. Tracers of specific activities have been identified in a number of studies and may help to provide estimates of the relative contribution of pollutant sources from heavily industrialized areas.

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“…Необходимым условием для получения новых материалов с прогнозируемыми и воспроизводимыми свойствами является определенный химический, фазовый состав и строение используемых микросфер. Использование технологической схемы разделения, включающей стадии гранулометрического разделения, аэродинамической классификации и магнитной сепарации [5][6][7], позволяет получить из концентратов ценосфер летучих зол от сжигания разных типов энергетических углей узкие фракции в интервале размеров 50-250 мкм постоянного химического и минерально-фазового состава с преобладающим содержанием глобул определенного морфологического типа. На их основе разработан ряд функциональных материалов, к которым относятся высокоселективные мембраны для диффузионного выделения гелия и контейнеры для хранения водорода [8][9][10], сенсибилизаторы эмульсионных взрывчатых веществ [11], капсулированные рН-чувствительные спиновые зонды для исследования биологических объектов [12], композитные сорбенты для извлечения радионуклидов из жидких радиоактивных отходов [13,14].…”

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“…Одним из перспективных направлений использования полых микросфер летучих зол, благодаря их низкой объемной плотности 0.2-0.8 г/см 3 [1,2,[5][6][7], представляется получение облегченных материалов различного назначения. Новым типом легких и высокопрочных материалов являются пропанты -сферические гранулы, которые выполняют функции расклинивающего агента, предотвращая смыкание образовавшихся трещин в современной добыче нефти и газа по технологии гидравлического разрыва пласта [15,16].…”

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Characteristics of the Narrow Fractions of Fly Ash Microspheres as the Basis of Light-Weight High-Strength Materials

Rogovenko

Kushnerova

Fomenko

2019

Journal of Siberian Federal University. Chemistry

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The narrow fractions of microspheres with a size of −0.4 + 0.2 mm with a low bulk density in the range of 0.34-0.64 g/cm 3 were separated from cenosphere concentrates of fly ashes and fly ash from local selection obtained from pulverized coal combustion. The main components of the chemical composition in obtained narrow fractions are SiO 2 -55-66 and Al 2 O 3 -21-40 wt. %. The part of amorphous glass phase are 63-93, the mullite phase are 1-34, the quartz phase are 2-8 and the calcite phase are 0-1 wt. %. It is found that microspheres, characterized by maximum values of bulk density 0.64 g/cm 3 and apparent thickness of the shell 20 μm, has the best strength properties. The successive twofold compressive loading the particles by increased strength were selected, for which the values of bulk density and apparent shell thickness increased to 0.86 g/cm 3 and 29 μm, respectively. It is shown that the spheres with the single-ring structure are primarily subjected to destruction; the particles with network and solid structure provide improved strength characteristics of narrow fractions of microspheres. Citation: Rogovenko E.S., Kushnerova O.A., Fomenko E.V. Characteristics of the narrow fractions of fly ash microspheres as the basis of light-weight high-strength materials,

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Composition and Morphology of Fly Ash Cenospheres Produced from the Combustion of Kuznetsk Coal

Cited by 84 publications

References 34 publications

Characterization of Fly Ash Cenospheres Produced from the Combustion of Ekibastuz Coal

Characterization of Fly Ash Cenospheres Produced from the Combustion of Ekibastuz Coal

Fine and Ultrafine Particles in the Vicinity of Industrial Activities: A Review

Characteristics of the Narrow Fractions of Fly Ash Microspheres as the Basis of Light-Weight High-Strength Materials

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