scholarly journals Separation of Cenospheres from Fly Ashes by Floatation Method

2010 ◽  
Vol 13 (1-2) ◽  
pp. 89 ◽  
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.

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

2016 ◽  
Vol 56 (4) ◽  
pp. 265-282 ◽  
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.

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

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.

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

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.

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

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1033 ◽  
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.

Material and Dynamics Analysis of Low-Temperature Superheater Pipe Bulging Accident in Utility Boiler

2012 ◽  
Vol 507 ◽  
pp. 117-122
Author(s):  
Zhong Yue ◽  
Yue Shan Zhang
Keyword(s):  
Low Temperature ◽  
Power Plants ◽  
Thermal Power ◽  
Strength Analysis ◽  
Composition Analysis ◽  
Dynamics Analysis ◽  
Pipe Failure ◽  
Environment Analysis ◽  
Metallurgical Analysis ◽  
Chemical Composition Analysis

Pipe failure accidents (bulging, bursting) are frequent in thermal power plants, and severely influence the safe and economic running. The authors analyzed the possible causes and features of low-temperature superheater pipe bulging. Taking the low-temperature superheater pipe bulging accident in a power plant for an example, the authors conducted macroscopic topography analysis, running environment analysis, metallurgical analysis, chemical composition analysis and strength analysis of the bulged pipe. Paper’conclusion was that the cause of low-temperature superheater pipe bulging wasn’t superheating, and the cause of bulging was flame straightening of the pipe during installation. The paper's innovation is material and dynamics analysis of the accident cause.

The Usability of Fly Ash for the Construction of Embankment Dams

2012 ◽  
Vol 587 ◽  
pp. 26-30
Author(s):  
Vit Cerný ◽  
Rostislav Drochytka ◽  
Jan Jandora
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Thermal Power ◽  
Raw Material ◽  
Site Testing ◽  
The Czech Republic ◽  
Embankment Dams ◽  
Different Types ◽  
Building Area ◽  
By Products

Power supplying industry in the Czech Republic is still dependent on thermal power plants. Due to the on-going and completed renovation of the existing power plant units, it is expected that they will be serviceable for the following 30 years. It is therefore necessary to look for suitable use of the by-products of these plants. Using the energy by-products during construction of dikes is currently limited to creation of little protective dikes on unloading yards of fly ash stabilizers. Here we can take advantage of the binding abilities of the energy by-product to stabilize the unloading yards and protect the environment. This method is technologically less effective for constructions of anti-flood dikes. Therefore we use the soils from the vicinity of the building area. A suitable method of using fly ash in water building industry lies in repairs of existing earth dams by using fly-ash and clay grouting that increase homogeneity, stability and impermeability of the dam. This paper deals with laboratory verification of suitability of different types of fly-ash in the mixture with special sealing clay. It also deals with designing optimal recipes for "on-site" testing. Results of the tests clearly recommend classical fly ash as the most suitable raw material. On the other hand, the bedding ash marked is not suitable for this technology.

Suitability of Malaysian Fly Ash for Geopolymer Synthesis

2016 ◽  
Vol 1133 ◽  
pp. 201-205 ◽  
Author(s):  
Ahmer Ali Siyal ◽  
Khairun Azizi Azizli ◽  
Lukman Ismail ◽  
Zakaria Man ◽  
Muhammad Irfan Khan
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Thermal Power ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Composition Analysis ◽  
Main Band ◽  
Amorphous Form ◽  
Suitable Material ◽  
Silica Alumina

Fly ash is a pozzolanic material which is produced during coal combustion in thermal power plants. This paper investigates the suitability of Malaysian fly ash for geopolymer synthesis. Chemical composition analysis, particle size analysis, amorphous and crystalline phases present, bonding nature, and microstructural behavior are used to determine the suitability of fly ash for geopolymer synthesis. The results showed that fly ash contains silica, alumina, ferrous oxide, and calcium oxide in major proportions which are the main ingredients required for geopolymer synthesis. Higher portion of particles having size in the range of 1-15 µm. Fly ash contains quartz, mullite, and ferrite as the crystalline compounds while the major portion of fly ash is in amorphous form. The band due to asymmetric stretching vibration mode of Si-O-T appears at 1095 cm-1 which is the main band used to follow geopolymer formation. Microstructure of fly ash shows that the higher portion of fly ash is in amorphous form while it contains cenospheres, magnetic spheres, carbon, and a large number of small particles. Malaysian fly ash is a suitable material for geopolymer and it can be used for geopolymer synthesis.

scholarly journals STUDIES ON COLONISATION OF FLY ASH DISPOSAL SITES USING INVASIVE SPECIES AND AROMATIC GRASSES

2017 ◽  
Vol 25 (3) ◽  
pp. 251-263 ◽  
Author(s):  
Deblina MAITI ◽  
Bably PRASAD
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Thermal Power ◽  
Farmyard Manure ◽  
Field Studies ◽  
Shoot Biomass ◽  
Future Research ◽  
High Concentration ◽  
Aromatic Grasses ◽  
Ash Disposal

Fly ash disposal activities by coal based thermal power plants will continue to be a serious issue across the globe due to its hiked generation every year. To obviate the hazardous effects of fly ash disposal sites on the surrounding ecosystems, rapid stabilization of the dumps is essential. This paper conglomerates the past activities, challenges; present scenario of vegetation establishment on these sites as well as future research requirements based on various experimental case studies. An insight has been presented on the usefulness of native, tuft, aromatic grasses which can reduce the length of successive phases in reclamation programmes and also enhance the fertility of the substrate as found from the significantly increased nitrogen content in the present field sites. Metal bioaccumulation studies depicted that by virtue of high biomass production potential of Saccharum spontaneum it can also be used as a phytoextractor of toxic metals, thus helping in phytoremediation of the metals in fly ash. Field studies allude the fact that knowledge of phytodiversity of old fly ash deposits is essential for a right choice of species before every reclamation programme. Secondly, application of amendments is conjointly a prerequisite for establishment of plants on fly ash. In a pot scale study it was found that lower rate of amendment application (2–5% farmyard manure and 5–10% topsoil on weight basis) in fly ash improves the growth and biomass of Cymbopogon citratus. Extensive root system of the grass was substantiated by high root: shoot biomass which stabilized the surface of the ash. To investigate the possibilities of ground water contamination due to amendments leaching studies were carried out. An initial high concentration of some ions marginally near permissible limit as per Indian drinking water standards was observed but their concentrations were below acceptable limit during harvestable stages. Above studies can contribute significantly in field studies through a properly planned restoration programme.

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

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Mehmet TANRIVERDI ◽  
Gül Akar ŞEN ◽  
Tayfun ÇIÇEK ◽  
Sezai ŞEN ◽  
Öznur ÖNEL
Keyword(s):  
Trace Elements ◽  
Fly Ash ◽  
Environmental Effect ◽  
Power Plants ◽  
Thermal Power ◽  
Leaching Tests ◽  
Application Area ◽  
Fly Ashes ◽  
Ecological Problems

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.

A Review on Utilization of Fly- Ash and Pond-Ash as a Partial Replacement of Cement in Concrete Mix Design

2018 ◽  
pp. 413-418
Author(s):  
Harshkumar Patel ◽  
Yogesh Patel
Keyword(s):  
Fly Ash ◽  
Electricity Generation ◽  
Power Plants ◽  
Renewable Energy Sources ◽  
Thermal Power ◽  
Strength Test ◽  
Partial Replacement ◽  
Pond Ash ◽  
Research Activities ◽  
Ash Disposal

Now-a-days energy planners are aiming to increase the use of renewable energy sources and nuclear to meet the electricity generation. But till now coal-based power plants are the major source of electricity generation. Disadvantages of coal-based thermal power plants is disposal problem of fly ash and pond ash. It was earlier considered as a total waste and environmental hazard thus its use was limited, but now its useful properties have been known as raw material for various application in construction field. Fly ash from the thermal plants is available in large quantities in fine and coarse form. Fine fly ash is used in construction industry in some amount and coarse fly ash is subsequently disposed over land in slurry forms. In India around 180 MT fly is produced and only around 45% of that is being utilized in different sectors. Balance fly ash is being disposed over land. It needs one acre of land for ash disposal to produce 1MW electricity from coal. Fly ash and pond ash utilization helps to reduce the consumption of natural resources. The fly ash became available in coal based thermal power station in the year 1930 in USA. For its gainful utilization, scientist started research activities and in the year 1937, R.E. Davis and his associates at university of California published research details on use of fly ash in cement concrete. This research had laid foundation for its specification, testing & usages. This study reports the potential use of pond-ash and fly-ash as cement in concrete mixes. In this present study of concrete produced using fly ash, pond ash and OPC 53 grade will be carried. An attempt will be made to investigate characteristics of OPC concrete with combined fly ash and pond ash mixed concrete for Compressive Strength test, Split Tensile Strength test, Flexural Strength test and Durability tests. This paper deals with the review of literature for fly-ash and pond-ash as partial replacement of cement in concrete.

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