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Abstract

Geopolymers are a new class of materials that can be synthesized using natural minerals, and waste materials. Among these substrates, the use of fly ash is desirable as it involves the conversion of a copious waste material into a useful product. The aim of the research was geopolymers synthesis from coal fly ash and biomass ash. Concentrated sodium hydroxide and sodium silicate solutions were used as activators in geopolymerisation reaction. The results show that both coal fly ash and biomass ash can be utilized as source materials for the production of geopolymers. The surface morphology and chemical composition analysis were examined for the obtained geopolymers and ashes from coal and biomass combustion by SEM-EDS methods. It was found almost total disappearance of spherical forms of grains and reduction the porosity of structure for geopolymer based on fly ash from coal combustion. While the structure of the geopolymer based ash from biomass combustion is more porous. The UV-VIS-NIR spectra were performed on the coal fly ash, biomass ash and geopolymers. They showed that the obtained geopolymers possess optical and photocatalytic properties. The similarity of the geopolymer network and the zeolite framework in relation to ion exchange and accommodation of metal ions open questions on possibilities for the application of geopolymer materials as amorphous analogues of zeolite. The FT-IR spectra analyses were used on the geopolymers before and after metals sorption. It was found that geopolymer based on ash from biomass combustion has better sorption properties compared to geopolymer based on ash from coal combustion.

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Authors and Affiliations

Elżbieta Sitarz-Palczak
Jan Kalembkiewicz
Dagmara Galas
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Abstract

Strength and permeability properties along with microstructural evolution of hardened slurries composed of fly ash from fluidal bed combustion of brown coal and an addition of OPC/BFSC is assessed in this paper. An increase in the amount of fly ash in slurries influences the development of mechanical strength and a decrease of hydraulic conductivity. SEM, XRD, and porosity analyses confirmed formation of watertight microstructures. The structure of slurries is composed of ettringite, C-S-H phase, AFt, and AFm phases. Ettringite crystallises as relatively short needles forming compact clusters or intermixed with the C-S-H phase. The occurring C-S-H phases are mainly of type I – fibrous and type II – honeycomb

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Authors and Affiliations

Z. Kledyński
P. Falaciński
A. Machowska
J. Dyczek
Ł. Kotwica
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Abstract

The article concerns fly ashes generated from the combustion of hard coal and deposited on landfills. Investigation results describing fly ash taken from a combustion waste landfill are presented in the article. The investigation results indicate a possibility for combusting the coal reclaimed by separation from the fly ash and utilizing the remaining fly ash fractions.

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Authors and Affiliations

Aleksandra Sambor
Arkadiusz Szymanek
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Abstract

Due to the fact that the landfill deposition of municipal waste with the higher heating value (HHV) than 6 MJ/kg in Poland is prohibited, the application of waste derived fuels for energy production seems to be good option. There is a new combined-heat-and-power (CHP) plant in Zabrze, where varied solid fuels can be combusted. The formation of ashes originating from the combustion of alternative fuels causes a need to find ways for their practical application and demands the knowledge about their properties. Therefore, the present work is devoted to studying the co-combustion of solid recovered fuel (SRF) and coal, its impact on fly ash quality and the potential application of ashes to synthesis zeolites. The major objectives of this paper is to present the detail characteristics of ash generated during this process by using the advanced instrumental techniques (XRF, XRD, SEM, B ET, TGA). The co-combustion were carried out at 0.1 MWth fluidized bed combustor. The amount of SRF in fuel mixture was 1, 5, 10 and 20%, respectively. The focus is on the comparison the ashes depending on the fuel mixture composition. Generally, the ashes characterise high amounts of SiO2, Al2O3 and Fe2O3. It is well observed, that the chemical composition of ashes from co-combustion of blends reflects the amount of SRF addition. Considering the chemical composition of studied ashes, they can be utilize as a zeolites A. The main conclusions is that SRF can be successfully combusted with coal in CFB technology and the fly ashes obtained from coal + SRF fuel mixtures can be used to synthesis zeolites.
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Authors and Affiliations

Aleksandra Ściubidło
Wojciech Nowak
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Abstract

One of the elements of the Polish Energy Policy program is the development of renewable energy, including energy from biomass combustion. In Poland, the Green Block was built at the Połaniec Power Station fired with 100% biomass fuel. This solution is conducive not only to obtaining energy but also to improving environmental protection. During the combustion of biomass in a fluidized bed boiler, about 50 thousand tons of fly ash per year being a source of nutrients for plants, for example potassium salts, phosphorus, calcium, boron compounds, etc. was derived. The subject of the research were three types of ashes from biomass combustion containing 80% dendromass and 20% agromass. Agromas was made of straw, dried material or sliced palm nuts. The physical characteristics and chemical composition of three basic fly ash samples are presented. Due to the high fineness and thus dusting during spreading, it was found that there is no possibility of the direct use of fly ash from biomass combustion as an alkalizing agent for acidic soils. The lowest bulk density was demonstrated by samples of fly ash originating from the combustion of biomass containing 20% straw as agromass, while the poorest in potassium and phosphorus were ash samples obtained from the combustion of biomass containing 20% agromass in the form of palm kernel slate. As additional components, mineral acids as well as inorganic compounds, including industrial waste, were used to correct the chemical composition and to mineral fertilizer granulation. The number of introduced components was related to the postulated composition of the produced fertilizer. Examples of mineral fertilizers obtained, both simple and multicomponent fertilizers, are presented.

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Authors and Affiliations

Sylwester Eugeniusz Żelazny
Andrzej Jarosiński
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Abstract

The durability characteristics of Engineered Cementitious Composites (ECC) with various fibers such as polypropylene and glass were investigated in view of developing composites with high resistance to cracking. ECC offer large potential for durable civil infrastructure due to their high tensile strain capacity and controlled micro-crack width. In this study, fibre volume fractions (0.5%, 1%, 1.5%, and 2%) of both polypropylene and glass fibers varied and durability measures such as a rapid chloride penetration test, sorptivity, water absorption, acid attack, and sulphate attack were measured. Increasing the fiber content up to 1.5% improved the durability properties of ECC. The test results indicate that the glass fiber-reinforced Engineered Cementitious Composites have better durability characteristics than polypropylene fiber-reinforced ECC.

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Authors and Affiliations

S. Ranjith
R. Venkatasubramani
V. Sreevidya
Keywords fly ash REE leaching
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Abstract

The aim of the work was to draw attention to the usefulness of the alkaline thermal activation process with sodium hydroxide in the process of rare earth metal leaching (REE), from fly ash with hydrochloric acid and nitric acid(V). The work is a part of the authors’ own research aimed at optimizing the REE recovery process coming from fly ash from hard coal combustion.

The article contains an assessment of the possibility of leaching rare earth metals (REE) from fly ash originating from the combustion of hard coal in one of the Polish power plants. The process was carried out for various samples consisting of fly ash and sodium hydroxide and for different temperatures and reaction times. The process was carried out for samples consisting of fly ash and sodium hydroxide containing respectively 10, 20 and 30% on NaOH by weight in relation to the weight of fly ash. Homogenization of these mixtures was carried out wet, and then they were baked at 408K, 433K and 473K, for a period of three hours. The mixture thus obtained was ground to a particle size of less than 0.1 mm and washed with hot water to remove excessive NaOH. The solid post-reaction residue was digested in concentrated HCl at 373K for 1 hour at a weight ratio fs/fc of 1:10. The results of chemical analysis and scanning microscopic analysis along with EDS analysis and X-ray analysis were used to characterize the physicochemical properties of the tested material.

The results indicated that REE recovery from fly ash strictly depends on heat treatment temperature with NaOH, and an increase in REE recovery from alkaline-activated fly ash along with increasing the amount of NaOH in relation to fly ash mass.

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Authors and Affiliations

Sylwester Żelazny
Henryk Świnder
ORCID: ORCID
Andrzej Jarosiński
Barbara Białecka
ORCID: ORCID
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Abstract

The galvanic sludges contain a number of toxic heavy metals, potentially mobilized as chemically active ions under environmental conditions as. This study explores the application of fly ash-based geopolymers for the removal of Zn ions from galvanizing sludge. In this study, geopolymers, synthesized via the geopolymerization method, were used to remove Zn from post-galvanized sewage sludge. Two types of geopolymers were used, derived from ash from coal combustion and biomass combustion. Structural, morphological, and surface properties were characterized using FTIR and SEM, respectively. In addition, BET and Langmuir isotherms, along with analyses such as t-Plot and BJH method for porous solids were conducted. The results indicate that the geopolymer derived from coal combustion ash is a more effective sorbent for Zn(II) ions, exhibiting a removal efficiency of 99.9%, compared to 40.7% for the geopolymer derived from biomass combustion ash. The FTIR spectra analysis reveals the presence of bonds between the -OH and/or Si-OH groups on the geopolymers’ surface and the Zn(II) ions. The environmentally and economically advantageous process maximizes the recovery of a valuable component at minimal cost, yielding relatively clean monometallic waste suitable for reuse.
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Authors and Affiliations

Elżbieta Sitarz-Palczak
1
ORCID: ORCID

  1. Rzeszow University of Technology, Poland
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Abstract

This article presents the results of the study of changes in mineral and chemical composition of artificial aggregates consisting of coal shale (a hard coal mining waste) and fluidized ashes. Such an aggregate was used for road construction. After completion of the construction works but before making the road available for public use, significant deformation of the surface in the form of irregular buckling of the asphalt layer occurred. It was excluded that this resulted from mining damage, design errors or performance mistakes, among others. A study of the materials that had been incorporated in the construction layers was undertaken in order to find the component and the mechanism responsible for the buckling of the road surface. A comparison of the mineral and chemical composition of aggregate samples collected from the embankment where the road buckled with the reference sample and samples from places without deformations showed that the bumps in the road embankment consisted of minerals that were not initially present in the aggregate. Wastes produced as a result of high temperatures (slag and power plants ashes, metallurgical wastes) are not as stable in terms of chemical and phase composition in the hypergenic environment. As a result of the processes occurring in the road embankment, anhydrite, which is the primary component of fluidized ashes, was transformed into gypsum and ettringite. As a result of contact with water CaO (present in fluidized ashes) easily changed into calcium hydroxide. As the crystallization of these minerals is expansive, it resulted in the filling of pores and, in extreme cases, in a substantial increase in the volume of the aggregate and, consequently, in the deformation of the road surface.
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Authors and Affiliations

Zdzisław Adamczyk
Marcin Grygierek
Marian Łupieżowiec
Jacek Nowak
Ewa Strzałkowska
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Abstract

The problem of of the use of fly ash still constitutes a research and exploration area for scientists. This is due to the fact that, 6,000,000 Mg of coal combustion by-products (CCB) are storage on landfills yearly in Poland alone. One of the potential directions of using fly ash is to use it as a substrate in hydrothermal syntheses of mesoporous materials (synthetic zeolites). Zeolites are aluminosilicates with a spatial structure. Due to their specific structure they are characterized by a number of specific properties among others molecular-sieve, ion-exchange and catalytic that can be used in engineering and environmental protection. So far, the synthesis has been carried out using coal combustion by-products such as fly ash or microsphere. The article analyzes whether separation from the fly ash of the appropriate fraction (below 63 μm) will affect the formation of zeolite grains. The syntheses were carried out using class F fly ash and the fraction separated from it, which was obtained by sieving the ash through a 63 μm sieve. Chemical (XRF) and mineralogical (XRD, SEM-EDS) analyzes were carried out for substrates as well as the obtained reaction products. In the case of substrates, the analysis did not show any significant differences between the ash and the separated fraction. However, in products after synthesis (Na-X zeolite with a small amount of Na-P1 zeolite, and small amounts of quartz and unreacted aluminosilicate glass - mullite) higher aluminum and sodium contents were observed from the separated fraction, with a lower calcium and potassium content. A small proportion of illite was observed on the diffraction curve of the zeolite from the fraction. Observations of grain morphology showed no differences in formation. Based on the conducted analyzes, it can be stated that, considering the economics of the synthesis process, the separation of fine fractions from the fly ash does not affect the quality of the synthesis process.

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Authors and Affiliations

Dorota Czarna-Juszkiewicz
Piotr Kunecki
Rafał Panek
Magdalena Wdowin
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Abstract

The reduction of mercury emissions in currently existing coal-based power plant solutions by each method i.e. preliminary, primary and secondary (consisting of introducing coal into the combustion chamber and then removing mercury from the combustion gases arising from the combustion process) does not solve the problem of achieving the required limits by power plants. Therefore, the need has arisen to look for new, effective solutions.

The results presented in the work concern the analysis of environmental benefits for the use of zeolites obtained from by-products of coal combustion such as fly ash (from hard coal and lignite) in technologies for removing gaseous forms of mercury. The tested zeolites were silver-modified X-type structures. The reference material in the considerations was active carbon impregnated with bromine – a commercially available sorbent on the market.

The article considers environmental benefits resulting from the use of tested zeolites taking the product life cycle, sorbent efficiency and the possibility of its regeneration compared to activated carbon (AC/Br) into account. The LCA analysis was performed taking the estimated material and energy balances of the manufacturing processes into account. When comparing the production process of type X zeolite materials on the processing line and activated carbons in the amount necessary to capture 375 g Hg from exhaust gases, the LCA analysis showed that zeolites contribute to a lower potential impact on the environment. The advantage is that 5 times less zeolite sorbent than activated carbons is needed to capture the same amount of mercury. In addition, zeolite materials can be regenerated, which extends their life time

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Authors and Affiliations

Łukasz Lelek
Magdalena Wdowin
ORCID: ORCID
Rafał Panek
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Abstract

Fly ash which has been separated from the flue gas stream as a result of fossil fuels combustion constitutes a huge amount of waste generated worldwide. Due to environmental problems, many directions of their rational use have been developed. Various attempts to convert fly ash into sorption materials, mainly synthetic zeolites, are conducted successfully. In this paper, an attempt was made to convert fly ash from lignite combustion from one of the Polish power plants, using alkaline hydrothermal synthesis. The primary phases in the fly ash were: quartz, gehlenite, mullite, hematite, feldspar, lime, anhydrite, occasionally grains of ZnO phase and pyrrhotite, glass and unburned fuel grains. As a result of hydrothermal synthesis a material containing new phases – pitiglianoite and tobermorite was obtained. Among the primary ash constituents, only gehlenite with an unburned organic substance, on which tobermorite with crystallized pitiglianoite was present. As a result of detailed testing of products after synthesis, it was found that among the tested grains:

• two populations can be distinguished – grains containing MgO and Fe2O3 as well as grains

containing Fe2O3 or MgO or containing none of these components,

• the main quantitative component was pitiglianoite,

• pitiglianoite was present in larger amounts in grains containing Fe2O3 or MgO or in the absence of both components than in grains in which Fe2O3 and MgO were found.

The results of the study indicate that in post-synthesis products, the contribution of components were as follows: pitiglianoite – 39.5% mas., tobermorite – 54% mas., gehlenite – 3% mas. and organic substance – 3.5% mas.

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Authors and Affiliations

Barbara Białecka
ORCID: ORCID
Zdzisław Adamczyk
ORCID: ORCID
Magdalena Cempa
ORCID: ORCID
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Abstract

Flexible and rigid road pavement deteriorates over time and needs high-performance patching repair materials. Cold mix asphalt patching is an easy and inexpensive repair material to repair potholes and other damaged roads. However, the repaired road pavement fails because it doesn’t have adequate compressive and bonding strength to the substrate. Thus, this research uses high-performance geopolymer repair materials to patch against road pavement potholes substrate. Geopolymer repair materials could improve the bonding strength, making them suitable for road repair purposes. For making geopolymer repair materials, the main materials used were high calcium aluminosilicate source materials such as fly ash, sodium hydroxide, sodium silicate, and water. This study tested the compressive and bonding strength of geopolymer repair materials after 1, 7, 14, and 28 days. This study found that the compressive strength of 90 g of alkali activator was the highest, at 37.0 MPa. The bonding strength improved gradually from day 1 to day 14, and then considerably on day 28. The compressive strength and bonding strength both increase in direct proportion to the amount of alkali activator present. Alkali activator is optimal at 90 grams for compressive strength and bonding strength of geopolymer repair materials.
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Authors and Affiliations

W.W.A. Zailani
1
ORCID: ORCID
N.M. Apandi
1
ORCID: ORCID
M.M.A. Abdullah
2
ORCID: ORCID
M.F.M. Tahir
2
ORCID: ORCID
I Nengah Sinarta
3
Komang Ayu Ni Agustini
3
ORCID: ORCID
S. Abdullah
1
ORCID: ORCID

  1. Universiti Teknologi MARA, College of Engineering, School of Civil Engineering, 40450 Shah Alam, Selangor, Malaysia
  2. Universiti Malaysia Perlis, Center of Excellence Geopolymer and Green Technology (CEGeoGTech), 01000 Kangar, Perlis, Malaysia
  3. Warmadewa University, Faculty of Engineering and Planning, Den Pasa r, 80239, Indonesia
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Abstract

The aim of this research was to assess the content and composition of the pollutants emitted by domestic central heating boilers equipped with an automatic underfeed fuel delivery system for the combustion chamber. The comparative research was conducted. It concerned fuel properties, flue gas parameters, contents of dust (fl y ash) and gaseous substances polluting the air in the flue gases emitted from a domestic CH boiler burning bituminous coal, pellets from coniferous wood, cereal straw, miscanthus, and sunflower husks, coniferous tree bark, and oats and barley grain. The emission factors for dust and gaseous air pollutants were established as they are helpful to assess the contribution of such boilers in the atmospheric air pollution. When assessing the researched boiler, it was found out that despite the development in design and construction, flue gases contained fly ash with a significant EC content, which affected the air quality.

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Authors and Affiliations

Jan Konieczyński
Ewelina Cieślik
Bogusław Komosiński
Tomasz Konieczny
Barbara Mathews
Tomasz Rachwał
Grzegorz Rzońca
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Abstract

The paper presents investigation results of the migration of a chemical compound contained in fly ash deposited on a dry furnace waste landfill site exposed to weather conditions. Climate conditions are able to significantly affect chemical component distribution in a block of deposited, moving chemical compounds to different depths. The main aim of the investigations was to determine the chemical component distribution of deposited fly ash in the landfill. Identification of chemical components based on XRF analysis indicated the existence of differences in both tested storage layer and the fraction of fly ash.

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Authors and Affiliations

Aleksandra Sambo
Arkadiusz Szymanek
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Abstract

The paper describes the results of various actions and industrial tests conducted in order to decrease the content of unburned carbon in the fly ash of a circulating fluidised bed combustor (CFBC). Several attempts to improve the situation were made and the effects of several parameters on the unburned carbon content in the fly ash were investigated (e.g. bed temperature, cyclone separation efficiency, fuel particle size distribution, boiler hydrodynamics, grid design, and fuel data). Unfortunately, no satisfactory solution to these problems was found. Probably, apart from attrition and char fragmentation, additional factors also contributed to the formation of unburned carbon in the CFBC fly ash.

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Authors and Affiliations

Rafał Kobyłecki
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Abstract

The study investigates chemical modifications of coal fly ash (FA) treated with HCl or NH4HCO3 or NaOH or Na2edta, based on the research conducted to examine the behaviour of Cd(II) and Pb(II) ions adsorbed from water solution on treated fly ash. In laboratory tests, the equilibrium and kinetics were examined applying various temperatures (293 - 333 K) and pH (2 - 11) values. The maximum Cd(II) and Pb(II) ions adsorption capacity obtained at 293 K, pH 9 and mixing time 2 h from the Langmuir model can be grouped in the following order: FA-NaOH > FA-NH4HCO3 > FA > FA-Na2edta > FA-HCl. The morphology of fly ash grains was examined via small-angle X-ray scattering (SAXS) and images of scanning electron microscope (SEM). The adsorption kinetics data were well fitted by a pseudo-second-order rate model but showed a very poor fit for the pseudofirst order model. The intra-particle model also revealed that there are two separate stages in the sorption process, i.e. the external diffusion and the inter-particle diffusion. Thermodynamics parameters such as free energy, enthalpy and entropy were also determined. A laboratory test demonstrated that the modified coal fly ash worked well for the Cd(II) and Pb(II) ion uptake from polluted waters.

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Authors and Affiliations

Eleonora Sočo
Jan Kalembkiewicz
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Abstract

In the paper, the technology of the production of the modified ceramic proppants used in the shale gas extracting process is described. The natural available materials and uncomplicated process to new ceramic proppants preparation were applied. The modification of the ceramic proppants based on the addition of the waste material as fly ash. The produced ceramic material in the form of granules characterized by high mechanical properties and low production costs. Moreover, the obtained good values of compressive strength and gas permeability for investigated proppants confirmed that this material has appropriate properties to be used in the hydraulic fracturing.
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Authors and Affiliations

B. Zboromirska-Wnukiewicz
K. Kasprzyk
K. Kogut
A. Dyjakon
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Abstract

Along with the increase in popularity of the sewage sludge thermal treatment methods in Poland

resulting from the implementation of European Union law, a management problem with ash, which is produced

as a result of this process, appeared. The paper analyses the chemical composition and physical properties of fl y

ash from thermal treatment of municipal sewage sludge in terms of its use in concrete technologies in relation to

EN 450-1 Fly ash for concrete. Defi nition, specifi cations and conformity criteria (2012) and EN 197-1 Cement.

Composition, specifi cations and conformity criteria for common cements (2011) standards. The tested material did

not meet the requirements related to use of fl y ash for concrete production (chemical composition, low activity

index, high water demand and fi neness), and as main and minor components for cement production. On the basis

of the carried out research and analyses, it was found that the hardening slurry technology creates the greatest

possibilities related to the management of fl y ash from thermal treatment of municipal sewage sludge.

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Authors and Affiliations

Łukasz Szarek
Małgorzata Wojtkowska
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Abstract

The use of fly ash as a material for earth structures involves its proper compaction. Fly ash compaction tests have to be conducted on separately prepared virgin samples because spherical ash grains are crushed during compaction, so the laboratory compaction procedure is time-consuming and laborious. The aim of the study was to determine the neural models for prediction of fly ash compaction curve shapes. The attempt of applying the artificial neural networks type MLP was made. ANN inputs were new-created variables – principal components dependent on grain-size distribution (as D₁₀–D₉₀ and uniformity and curvature coefficients), compaction method, and fly ash specific density. The output vectors were presented by co-ordinates of generated compaction curve points. Each point (wᵢ, ρdi) was described by two independent ANNs. Using ANN-based modelling method, models which enable establishing the approximate compaction curve shape were obtained.

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Authors and Affiliations

K. Zabielska-Adamska
M.J. Sulewska
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Abstract

The cenospheres are formed during the mineral transformation stage in coal combustion. Their content in fly ashes from the combustion of different types of coals varies over a rather wide range from 0.01 to 35.6 wt.%. The cenospheres has three main elements, silicon, aluminium and iron, the oxides of which account for about 89% of the material. Mineralogical analysis using XRD shows that as-received cenospheres mainly contain mullite and quartz as main mineralogical phases. The size of cenospheres varies between 5 and 500 [...], as the most common dimension is 20-300 [...]. The cenospheres are characterized by a low bulk density (0.2-0.8 g/cm3) and can be easily separated by gravitational methods in the form of a concentrate in aqueous media or collected from a water surface of lagoons intended for storage of ash and slag waste. The unique properties of these hollow microspheres make them amenable for wide applications. For example the cenospheres can be used to produce various lightweight construction products, including lightweight cements and aggregates in lightweight concrete.

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Authors and Affiliations

Elżbieta Haustein
Bernard Quant

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