Fly Ashes: Characterization, Processing and Utilization

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Environmental Mineralogy and Biogeochemistry".

Deadline for manuscript submissions: closed (30 November 2022) | Viewed by 12980

Special Issue Editors

Mineral and Energy Economy Research Institute of the Polish Academy of Sciences, 31-261 Krakow, Poland
Interests: waste management; energy policy; renewable energy sources; management of mineral resources
Faculty of Civil Engineering and Resource Management, AGH University of Science and Technology, 30-059 Krakow, Poland
Interests: waste management; mineral waste recovery; CCSU; renewable energy sources
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Solid fuels are the chief energy source in many countries in the world. These include conventional fossil fuels and renewable energy sources, such as biomass. When used, they generate by-products of combustion, mainly fly ashes. The quantity and quality of such waste primarily depend on the type of fuel burned and the combustion technology employed. These factors contribute to fly ashes having very varied and changeable characteristics.

Fly ashes produced from the burning of hard coal and brown coal, as well as the co-combustion of biomass, have been used as raw materials in numerous industries for many years now. Nevertheless, numerous studies are still being conducted on new areas of fly ash utilization and improvements to the existing technologies. On the other hand, fly ashes from the combustion of biomass are difficult to process. However, the importance of biomass as a renewable energy source encourages the continued employment of current biomass utilization methods.  Additionally, new opportunities for utilizing biomass-derived fly ashes in various industries should be identified.

Authors are invited to submit papers addressing topics from the broad field of fly ash characteristics and fly ash recovery possibilities.

Prof. Dr. Eugeniusz Mokrzycki
Prof. Dr. Alicja Uliasz-Bocheńczyk
Guest Editors

Manuscript Submission Information

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Keywords

  • by-product utilization
  • building materials technology
  • circular economy
  • waste management
  • stabilization/solidification
  • geopolymers
  • CO2 mineral sequestration
  • sorbents
  • source of rare earth elements
  • geoengineering
  • recovery
  • mineral processing
  • fly ash
  • bottom ash
  • soil quality improvement
  • reclamation
  • mining

Published Papers (5 papers)

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Research

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10 pages, 1625 KiB  
Article
Recovered Fly Ashes as an Anthropogenic Raw Material
by Alicja Uliasz-Bocheńczyk and Eugeniusz Mokrzycki
Minerals 2023, 13(5), 623; https://0-doi-org.brum.beds.ac.uk/10.3390/min13050623 - 29 Apr 2023
Viewed by 920
Abstract
Poland is a country where the commercial power industry mainly uses coal to produce energy. As a result of energy production processes, by-products of combustion are generated, primarily fly ashes. In Poland, these are mostly obtained from conventional coal combustion boilers. Fly ashes [...] Read more.
Poland is a country where the commercial power industry mainly uses coal to produce energy. As a result of energy production processes, by-products of combustion are generated, primarily fly ashes. In Poland, these are mostly obtained from conventional coal combustion boilers. Fly ashes from coal combustion account for 1.2% of all industrial waste generated in Poland. In addition, fly ashes are produced by fluidized-bed boilers. These are classified as a mixture of fly ashes and solid calcium-based reaction waste from flue-gas desulphurization, and constitute almost 2% of Polish industrial waste. This paper describes the amounts of fly ashes generated in Poland and considers activities related to their recovery and disposal. The high recovery levels of fly ashes (about 90%) and fluidized ashes (about 98%) mean that these waste products can also be considered anthropogenic raw materials. The use of these materials in the cement industry is an example of industrial symbiosis. Such usage benefits not only the economy but also the environment and, therefore, society as a whole. To describe the use of recovered fly ashes in cement plants, the authors use the anthropogenicity index, which characterizes the level of technological advancement and the substitutability of primary raw materials for secondary raw materials. Full article
(This article belongs to the Special Issue Fly Ashes: Characterization, Processing and Utilization)
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12 pages, 2966 KiB  
Article
Potential Use of Municipal Waste Incineration Ash as a Hardening Slurry Ingredient
by Paweł Falaciński and Łukasz Szarek
Minerals 2022, 12(5), 655; https://0-doi-org.brum.beds.ac.uk/10.3390/min12050655 - 23 May 2022
Cited by 1 | Viewed by 1508
Abstract
In recent years, there has been a marked increase in the amount of municipal waste generated in Poland. In the context of circular economy assumptions, the key is the availability of technologies that would make it possible to safely process and reuse waste, [...] Read more.
In recent years, there has been a marked increase in the amount of municipal waste generated in Poland. In the context of circular economy assumptions, the key is the availability of technologies that would make it possible to safely process and reuse waste, especially when it is difficult to manage. One such direction is thermal waste treatment. In 2020, 21.6% of all municipal waste was subjected to this process. Consequently, the amount of ash generated is significant (approximately 2,823,000 tons annually). One of the uses of waste materials is the sealing of earth hydrotechnical facilities, such as flood embankments, water dams, and embankments of waste landfills. For this purpose, cut-off screens made of hardening slurries are used. In order to improve the tightness and corrosion resistance of hardening suspensions, combustion by-products are added to their composition. The article presents an assessment of the possibility of using ashes from municipal waste incineration as an additive to hardening slurries. It also discusses the technological and operational parameters of hardening slurries with the addition of the ashes in question. Binding requirements for hardening slurries used for the construction of cut-off walls is also defined. The experiment showed that the tested hardening slurries meet most of the suitability criteria. Further research directions are proposed to fully identify other properties of hardening slurries in terms of their environmental impact. Full article
(This article belongs to the Special Issue Fly Ashes: Characterization, Processing and Utilization)
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32 pages, 4257 KiB  
Article
Integrative Study Assessing Space and Time Variations with Emphasis on Rare Earth Element (REE) Distribution and Their Potential on Ashes from Commercial (Colombian) Coal
by Ana Cláudia Santos, Alexandra Guedes, David French, Aurora Futuro and Bruno Valentim
Minerals 2022, 12(2), 194; https://0-doi-org.brum.beds.ac.uk/10.3390/min12020194 - 02 Feb 2022
Cited by 6 | Viewed by 1870
Abstract
The increasing demand for rare earth elements (REEs), which is associated with their economic importance and the supply risk, has motivated the research for alternative secondary sources of these elements. Coal and coal combustion ash have been pointed out as promising REE raw [...] Read more.
The increasing demand for rare earth elements (REEs), which is associated with their economic importance and the supply risk, has motivated the research for alternative secondary sources of these elements. Coal and coal combustion ash have been pointed out as promising REE raw materials. This research seeks to understand REE fractionation, from feed coals to ashes, considering seasonal variations, and to assess the trends within the ash fractions that can be used for further beneficiation processes. Colombian commercial feed coals, combustion ashes, and their respective fractions were sampled from a Portuguese power plant and were characterized via petrographical, mineralogical, and chemical analyses. The total REE concentrations in the feed coals studied range between 6.97 and 23.15 ppm, while, in the ashes, they vary from 159.9 to 266.6 ppm. Fly ash (FA) from electrostatic precipitator (ESP) presented higher concentrations than the bottom (BA) and economizer (ECO) ashes. Furthermore, REEs and the LREE/HREE ratio increased slightly towards the back rows of the ESP. In the feed coals, the REEs are significantly correlated with ash, and they occur in micrometric phosphate minerals intermixed with clays. In the ashes, the REEs were mostly detected in micrometric particles, with P and Al-Si as the major components. The results from the fractioned samples show that the REEs were enriched in the fine (<25 µm) and nonmagnetic fractions of the ESP FA. A single trial combining sieving and magnetic separation enabled the attainment of a REE recovery of 53%, and a final enrichment factor of 1.25. Coal combustion ashes and their respective size fractions are promising REE raw materials; however, the REE oxide concentrations are below the economical cutoff of 1000 ppm. Full article
(This article belongs to the Special Issue Fly Ashes: Characterization, Processing and Utilization)
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Review

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16 pages, 1843 KiB  
Review
Recycling of Coal Fly Ash in Building Materials: A Review
by Xuhang Lu, Bo Liu, Qian Zhang, Quan Wen, Shuying Wang, Kui Xiao and Shengen Zhang
Minerals 2023, 13(1), 25; https://0-doi-org.brum.beds.ac.uk/10.3390/min13010025 - 23 Dec 2022
Cited by 13 | Viewed by 2937
Abstract
Coal fly ash (CFA) is a type of solid waste produced in the process of coal combustion, which is rich in silicon oxide, aluminum oxide and a small number of heavy metals and radioactive elements. Therefore, CFA is considered a secondary resource with [...] Read more.
Coal fly ash (CFA) is a type of solid waste produced in the process of coal combustion, which is rich in silicon oxide, aluminum oxide and a small number of heavy metals and radioactive elements. Therefore, CFA is considered a secondary resource with high recovery value. Currently, CFA is mainly reused in the fields of building materials, mine backfilling, soil conditioners and fertilizers, among which the production of building materials is one of the most important ways to realize large-scale utilization of CFA. This paper introduces the physical and chemical properties, classification and environmental impact of CFA and summarizes the utilization status of CFA in building materials such as cement, concrete, ceramics and geopolymers, as well as the management policy of CFA. In addition, the existing problems in the utilization of CFA as a building material are analyzed, and their development prospects are discussed. Full article
(This article belongs to the Special Issue Fly Ashes: Characterization, Processing and Utilization)
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23 pages, 1273 KiB  
Review
Status of Coal-Based Thermal Power Plants, Coal Fly Ash Production, Utilization in India and Their Emerging Applications
by Virendra Kumar Yadav, Amel Gacem, Nisha Choudhary, Ashita Rai, Pankaj Kumar, Krishna Kumar Yadav, Mohamed Abbas, Nidhal Ben Khedher, Nasser S. Awwad, Debabrata Barik and Saiful Islam
Minerals 2022, 12(12), 1503; https://0-doi-org.brum.beds.ac.uk/10.3390/min12121503 - 25 Nov 2022
Cited by 25 | Viewed by 4596
Abstract
Both fossil and renewable fuel sources are used widely to produce electricity around the globe. The dependency on fossil fuels for energy leads to the depletion of reserves and various forms of pollution. Coal fly ash (CFA) is one of the most burning [...] Read more.
Both fossil and renewable fuel sources are used widely to produce electricity around the globe. The dependency on fossil fuels for energy leads to the depletion of reserves and various forms of pollution. Coal fly ash (CFA) is one of the most burning issues in the whole world due to its large amount of production in thermal power plants. Every year a million tons (MTs) of CFA are generated globally of which almost half is utilized in various forms, while the remaining half remains unused, leading to various types of pollution. Hence, there is an immediate requirement for CFA management approaches for the efficient and sustainable use of fly ash. In the present review, the authors emphasize the status of energy and its supply and demand. A detailed description of coal fly ash-based thermal power plants, fly ash production, and utilization is provided. Moreover, the current and emerging applications of CFA are also provided. Full article
(This article belongs to the Special Issue Fly Ashes: Characterization, Processing and Utilization)
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