Separation of unburned carbon from coal fly ash: A review

Xing, Yaowen; Guo, Fengjie; Xu, Min; Gui, Xiahui; Li, Haisheng; Li, Guosheng; Xia, Yangchao; Han, Haisheng

doi:10.1016/j.powtec.2019.05.037

Cited by 106 publications

(46 citation statements)

References 76 publications

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“…Almost 45% of carbon emissions (energy related) is caused by coal combustion processes [ 1 ]. Currently, fly ash is most often deposited in landfills which leads to deterioration of the environment and human health [ 2 ]. The most common way of its disposal is using them in civil engineering (as an additive in cement industry) [ 3 ].…”

Section: Introductionmentioning

confidence: 99%

“…However, this application imposes certain limitations related to the chemical composition of the ash. Nowadays, new technologies introduced in power plants and thermal power plants have a negative impact on the chemical composition of fly ash, e.g., by increasing the content of unburned coal that excludes their use in the construction industry [ 2 , 4 ]. Fly ashes are comoposed of aluminosilicate glaze (65–78%) and a crystalline part in the form of mullite, quartz, and hematite, magnetite, or calcite [ 5 , 6 ].…”

Section: Introductionmentioning

confidence: 99%

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Recycling of Waste Solution after Hydrothermal Conversion of Fly Ash on a Semi-Technical Scale for Zeolite Synthesis

et al. 2021

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Nowadays, using fly ash for zeolites production has become a well-known strategy aimed on sustainable development. During zeolite synthesis in a hydrothermal conversion large amount of post-reaction solution is generated. In this work, the solution was used as a substrate for Na-A and Na-X zeolites synthesis at laboratory and technical scale. Obtained materials were characterized using particle size analysis, X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), transmission electron microscopy (TEM), Fourier transformed infrared spectroscopy (FTIR), and nitrogen adsorption/desorption isotherm. Produced zeolites revealed high purity (>98%) and monomineral zeolitic phase composition. The SiO2 content was in the range 39–42% and 40–38%, whereas Al2O3 content was 23–22% and 25–26% for Na-X and Na-A, respectively. TEM and BET analyses revealed Na-X zeolite pores were almost identical to commercial 13X with SBET in the range 671–734 m2/g. FTIR indicated slight differences between materials obtained at laboratory and technical scale in Si-O-(Si/Al) bridges of the zeolitic skeleton. The results showed good replicability of the laboratory process in the larger scale. The proposed method allows for waste solution reusability with a view to highly pure zeolites production in line with circular economy assumptions.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Recycling of Waste Solution after Hydrothermal Conversion of Fly Ash on a Semi-Technical Scale for Zeolite Synthesis

et al. 2021

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“…It is estimated that approximately 750 million tonnes of coal ash are generated every year in the coal industry throughout the world. A significant volume of coal fly ash is produced by major industrial countries, where it is one of the largest single sources of industrial solid waste [6].…”

Section: Introductionmentioning

confidence: 99%

Coal Combustion Products Management toward a Circular Economy—A Case Study of the Coal Power Plant Sector in Poland

Bielecka

Kulczycka

2020

Energies

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Coal combustion products can be considered as commercial products or waste depending on the quality of the coal, the combustion process, and the country’s legislation. The circular economy can create incentives for the implementation of new business models in large power plants in cooperation with coal mines and users of coal combustion products. This is particularly important in Poland, where coal still remains the main source of energy, employing over 80,000 workers. The objective of this study was to assess the readiness for change toward a circular economy and to identify challenges, barriers, and plans at seven large power plants. To do this, a final questionnaire was developed after checking environmental reporting, a CATI survey, and brainstorming between circular economy leaders from science, industry, and non-governmental organizations. The results indicate that even if the great economic and environmental potential of coal combustion products management are understood, all requirements connected with CO2 and air pollution have higher priorities. Policy shifts away from coal do not promote cooperation, but the higher acceptance of products from waste and more transparent data shows a large potential for changes toward a circular economy.

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“…However, the size of most fly ash particles is less than 74 µm, more abundant information can be obtained by studying from the microscopic perspective. Xing et al (2019) analyzed the three forms of carbon and ash in fly ash by scanning electron microscopy and pointed out the existence position and shape of carbon. The results showed that triboelectrostatic beneficiation is suitable for the separation of monomer carbon, and the surface attached carbon particles can be flotation.…”

Section: Introductionmentioning

confidence: 99%

The influence of micro-morphology and micro-structure on fly ash triboelectrostatic beneficiation

Wang¹,

Chen²,

Li³

et al. 2020

Physicochem. Probl. Miner. Process.

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Fly ash is a complex system with a variety of fine particles. The complex relationship between unburned carbon and ash particles has an important influence on the efficiency of fly ash triboelectrostatic beneficiation. The particles adhered to the two electrode plates are collected through the triboelectrostatic beneficiation experiment. The scanning electron microscopy and X-ray fluorescence are used to detect the microscopic differences between the particles of positive and negative plates. The results show that the flaky carbon particles in the raw ash and the ash particles larger than 4µm are more easily separated, while it is converse for the ash particles with particle size less than 4µm. With the particle size less than 4µm, it is gradually more obvious for the influence of adhesion caused by the roughness surface of spherical unburned carbon particles, and the surface pores structure of porous carbon particles. The binding structure between unburned carbon and ash particles is complex and changeable. It is not beneficial to improve the separation efficiency. Therefore, the microstructure and micro-morphology have an important effect on fly ash triboelectrostatic beneficiation. Some suggestions were proposed from the microscopic point to improve the efficiency of fly ash triboelectrostatic beneficiation.

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Separation of unburned carbon from coal fly ash: A review

Cited by 106 publications

References 76 publications

Recycling of Waste Solution after Hydrothermal Conversion of Fly Ash on a Semi-Technical Scale for Zeolite Synthesis

Recycling of Waste Solution after Hydrothermal Conversion of Fly Ash on a Semi-Technical Scale for Zeolite Synthesis

Coal Combustion Products Management toward a Circular Economy—A Case Study of the Coal Power Plant Sector in Poland

The influence of micro-morphology and micro-structure on fly ash triboelectrostatic beneficiation

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