Leachability of Heavy Metals from Autoclaved Fly Ash-Lime Building Bricks

The fly ash as a byproduct of coal-fired power plants constitutes vital ecological problems. In Turkey, approximately 15 million tons ofashes are generated via the combustion of 40 million tons of lignite yearly. Worldwide, a number of investigation and applications wereundertaken to utilize fly ash in order to overcome the environmental problems. One of the application area of fly ashes is the production of building bricks. Characterization of fly ash samples from Seyitomer and Yatagan coal-firing power plants were conducted inthis study. TCLP 1311, ASTM3987-85 and EN 12457-2 leaching tests on the cylindrical fly ash/lime brick (FA/LB) samples which wereproduced from Seyitömer and Yatagan thermal power plant fly ash-lime mixtures were performed to determine the leachability ofsome chosen trace elements. The results show that the release of all trace elements was lower than the hazardous material limit valuesof waste acceptance. Thus, non- fired fly ash bricks are an advantageous way to solving environmental effect of disposal of fly ashes.

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Assessment of Characteristics of Acid Mine Drainage Treated with Fly Ash

Applied Sciences ◽

10.3390/app11093910 ◽

2021 ◽

Vol 11 (9) ◽

pp. 3910

Author(s):

Saba Shirin ◽

Aarif Jamal ◽

Christina Emmanouil ◽

Akhilesh Kumar Yadav

Keyword(s):

Fly Ash ◽

Acid Mine Drainage ◽

Power Plants ◽

Mine Drainage ◽

Thermal Power ◽

Mineralogical Characterization ◽

Acid Mine ◽

Before And After ◽

Abandoned Coal Mines

Acid mine drainage (AMD) occurs naturally in abandoned coal mines, and it contains hazardous toxic elements in varying concentrations. In the present research, AMD samples collected from an abandoned mine were treated with fly ash samples from four thermal power plants in Singrauli Coalfield in the proximate area, at optimized concentrations. The AMD samples were analyzed for physicochemical parameters and metal content before and after fly ash treatment. Morphological, geochemical and mineralogical characterization of the fly ash was performed using SEM, XRF and XRD. This laboratory-scale investigation indicated that fly ash had appreciable neutralization potential, increasing AMD pH and decreasing elemental and sulfate concentrations. Therefore, fly ash may be effectively used for AMD neutralization, and its suitability for the management of coalfield AMD pits should be assessed further.

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DETERMINING THE ROLE OF INDIVIDUAL FLY ASH PARTICLES IN INFLUENCING THE VARIATION IN THE OVERALL PHYSICAL, MORPHOLOGICAL, AND CHEMICAL PROPERTIES OF FLY ASH

Acta Polytechnica ◽

10.14311/ap.2016.56.0265 ◽

2016 ◽

Vol 56 (4) ◽

pp. 265-282 ◽

Cited By ~ 2

Author(s):

Usman Haider ◽

Zdenek Bittnar ◽

Lubomír Kopecky ◽

Vít Šmilauer ◽

Jaroslav Pokorny ◽

...

Keyword(s):

Fly Ash ◽

Power Plants ◽

Thermal Power ◽

Chemical Properties ◽

Cementitious Materials ◽

Individual Particle ◽

Particle Analysis ◽

Fly Ashes ◽

Alumino Silicate ◽

Individual Particles

The properties of fly ashes vary because of the differences in the properties of their individual particles, and the determination of variation in these properties is of interest to the industries which use pulverized raw fly ash in applications, such as in cementitious materials and in the recovery of certain rare elements from raw fly ash. To investigate the differences in individual particles, four pulverized raw fly ashes from thermal power plants of the Czech Republic were used in this research. It was observed from FE-SEM that all four fly ashes consist of glassy hollow spherical, solid spherical, porous spherical, bright spherical, porous slaggy and compact slaggy particles. Box and whisker diagrams were plotted from the data of EDX individual particle analyses, which showed that the data of percentages for the Si, Al, and Fe elements is more scattered as compared to other elements. It was further observed from ternary phase diagrams and pseudo coloured images, that nature of fly ash particles changes from alumino silicate glassy to alumino silicate calcite metallic to pure ferro-metallic,where glassy particles showed high percentages and pure calcite particles were absent in fly ashes. Furthermore, a comparison between the XRF, the EDX total area analyses, showed that the EDX individual particle analysis gives more realistic and reliable data with median, mean, and the standard deviation for percentages of each element present in the fly ashes.

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The Suitability of Fly Ash for Use in Concrete According to EN 450 Based on their Particle Size

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.276.110 ◽

2018 ◽

Vol 276 ◽

pp. 110-115

Author(s):

Martin Ťažký ◽

Martin Labaj ◽

Rudolf Hela

Keyword(s):

Fly Ash ◽

Power Plants ◽

Catalytic Reduction ◽

Raw Materials ◽

Thermal Power ◽

Combustion Process ◽

Thermal Power Plants ◽

Mechanical Parameters ◽

Fly Ashes ◽

The Impact

The by-products of energy industry are nowadays often affected by new limits governing the production of harmful gases discharged into the air. These stricter and stricter criteria are often met by electricity producers by changing the combustion process in thermal power plants itself. Nowadays, the SNCR (selective non-catalytic reduction) application is quite common in the combustion process in order to help reduce the nitrogen oxide emission. This article deals with the primary measures of thermal power plants, which in particular consist of a modified treatment of raw materials (coal) entering the combustion process. These primary measures then often cause the formation of fly ash with unsuitable fineness for the use in concrete according to EN 450. The paper presents the comparison of the physico-mechanical parameters of several fly ashes with a different fineness values. The primary task is to assess the impact of non-suitable granulometry in terms of EN 450 on the other physico-mechanical parameters of fly ashes sampled within the same thermal power plant. Several fly ashes produced in the Czech Republic and surrounding countries were evaluated in this way.

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Separation of Cenospheres from Fly Ashes by Floatation Method

Eurasian Chemico-Technological Journal ◽

10.18321/ectj72 ◽

2010 ◽

Vol 13 (1-2) ◽

pp. 89 ◽

Cited By ~ 4

Author(s):

L.M. Manоcha ◽

K.A. Ram ◽

S.M. Manocha

Keyword(s):

Fly Ash ◽

Power Plants ◽

Thermal Power ◽

Ceramic Particle ◽

Composition Analysis ◽

High Concentration ◽

Fly Ashes ◽

Power Station ◽

Different Types ◽

Chemical Composition Analysis

Fly-ashes are non-combustible mineral residues which are produced from coal in thermal power plants. Four different types of fly ashes were collected from different power station in Gujarat. Characterization through SEM shows that fly ash contains cenosphere i.e. gas bubble containing ceramic particle independent of their bulk density. Floatation technique was used for the separation of cenosphere from fly ash. Two solvents with extremely different densities were used for the separation of cenospheres. All methods gave approximately yield of less than 1 % cenosphere in fly ash. Color of cenospheres varied from gray to almost white and the value of density range from 0.4 – 0.8 g/cc. Further, chemical composition analysis revealed that cenospheres do not contain any high concentration of hazardous elements.

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Stabilization of Indian Fly Ashes with Soils, Cement, and Randomly Oriented Fibers

Journal of Civil Engineering Science and Technology ◽

10.33736/jcest.96.2012 ◽

2012 ◽

Vol 3 ◽

pp. 1-8

Author(s):

Shenbaga R. Kaniraj ◽

V. Gayathri ◽

V.G. Havanagi

Keyword(s):

Fly Ash ◽

Power Plants ◽

Thermal Power ◽

Experimental Studies ◽

Fly Ashes ◽

Strength Criteria ◽

Permeability Characteristics ◽

Polyester Fibers ◽

Soil Mixtures ◽

Pavement Base

Experimental studies were carried out on fly ashes from two Indian thermal power plants, namely Rajghat and Dadri, with the aim of improving the utilization of fly ash in geotechnical engineering applications. It was attempted to improve the engineering performance of fly ash by several means such as by mixing fly ash with soils, cement, and polyester fibers. The research program included the study of: a) physical properties, chemical composition and morphology of the fly ashes; b) compaction, strength, and permeability characteristics of the fly ashes and fly ash-soil mixtures; c) compaction and strength characteristics of fly ash-soil mixtures stabilized with fibers alone, with cement alone, and with both cement and fibers. Results showed that addition of fly ash to soils would result in lighter and stronger fills. Fiber inclusions increased the strength of fly ash-soil specimens significantly and altered their behaviour from brittle to ductile. Even small cement contents increased the strength of the fly ash-soil mixtures significantly. With higher cement contents of up to 18% it was possible to prepare fly ash-cement design mixes that satisfied the strength criteria for pavement base courses.

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Influence of Activators on Mechanical Properties of Modified Fly Ash Based Geopolymer Mortars

Materials ◽

10.3390/ma13051033 ◽

2020 ◽

Vol 13 (5) ◽

pp. 1033 ◽

Cited By ~ 4

Author(s):

Piotr Prochon ◽

Zengfeng Zhao ◽

Luc Courard ◽

Tomasz Piotrowski ◽

Frédéric Michel ◽

...

Keyword(s):

Fly Ash ◽

Power Plants ◽

Thermal Power ◽

Biomass Combustion ◽

Fly Ashes ◽

Binding Properties ◽

Alkali Activated ◽

Modified Fly Ash ◽

Scanning Electron ◽

And Calorimetry

The aim of this work was to study the influence of the type of activator on the formulation of modified fly ash based geopolymer mortars. Geopolymer and alkali-activated materials (AAM) were made from fly ashes derived from coal and biomass combustion in thermal power plants. Basic activators (NaOH, CaO, and Na2SiO3) were mixed with fly ashes in order to develop binding properties other than those resulting from the use of Portland cement. The results showed that the mortars with 5 mol/dm3 of NaOH and 100 g of Na2SiO3 (N5-S22) gave a greater compressive strength than other mixes. The compressive strengths of analyzed fly ash mortars with activators N5-S22 and N5-C10 (5 mol/dm3 NaOH and 10% CaO) varied from 14.3 MPa to 5.9 MPa. The better properties of alkali-activated mortars with regular fly ash were influenced by a larger amount of amorphous silica and alumina phases. Scanning electron microscopy and calorimetry analysis provided a better understanding of the observed mechanisms.

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