WorldWideScience
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Toxicity mitigation and solidification of municipal solid waste incinerator fly ash using alkaline activated coal ash  

International Nuclear Information System (INIS)

Highlights: ? Incinerator fly ash (IFA) is added to an alkali activated coal fly ash (CFA) matrix. ? Means of stabilizing the incinerator ash for use in construction applications. ? Concrete made from IFA, CFA and IFA-CFA mixes was chemically characterized. ? Environmentally friendly solution to IFA disposal by reducing its toxicity levels. - Abstract: Municipal solid waste (MSW) incineration is a common and effective practice to reduce the volume of solid waste in urban areas. However, the byproduct of this process is a fly ash (IFA), which contains large quantities of toxic contaminants. The purpose of this research study was to analyze the chemical, physical and mechanical behaviors resulting from the gradual introduction of IFA to an alkaline activated coal fly ash (CFA) matrix, as a mean of stabilizing the incinerator ash for use in industrial construction applications, where human exposure potential is limited. IFA and CFA were analyzed via X-ray fluorescence (XRF), X-ray diffraction (XRD) and Inductive coupled plasma (ICP) to obtain a full chemical analysis of the samples, its crystallographic characteristics and a detailed count of the eight heavy metals contemplated in US Title 40 of the Code of Federal Regulations (40 CFR). The particle size distribution of IFA and CFA was also recorded. EPA’s Toxicity Characteristic Leaching Procedure (TCLP) was followed to monitor the leachability of the contaminants before and after the activation. Also images oer the activation. Also images obtained via Scanning Electron Microscopy (SEM), before and after the activation, are presented. Concrete made from IFA, CFA and IFA-CFA mixes was subjected to a full mechanical characterization; tests include compressive strength, flexural strength, elastic modulus, Poisson’s ratio and setting time. The leachable heavy metal contents (except for Se) were below the maximum allowable limits and in many cases even below the reporting limit. The leachable Chromium was reduced from 0.153 down to 0.0045 mg/L, Arsenic from 0.256 down to 0.132 mg/L, Selenium from 1.05 down to 0.29 mg/L, Silver from 0.011 down to .001 mg/L, Barium from 2.06 down to 0.314 mg/L and Mercury from 0.007 down to 0.001 mg/L. Although the leachable Cd exhibited an increase from 0.49 up to 0.805 mg/L and Pd from 0.002 up to 0.029 mg/L, these were well below the maximum limits of 1.00 and 5.00 mg/L, respectively.

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Toxicity mitigation and solidification of municipal solid waste incinerator fly ash using alkaline activated coal ash.  

Science.gov (United States)

Municipal solid waste (MSW) incineration is a common and effective practice to reduce the volume of solid waste in urban areas. However, the byproduct of this process is a fly ash (IFA), which contains large quantities of toxic contaminants. The purpose of this research study was to analyze the chemical, physical and mechanical behaviors resulting from the gradual introduction of IFA to an alkaline activated coal fly ash (CFA) matrix, as a mean of stabilizing the incinerator ash for use in industrial construction applications, where human exposure potential is limited. IFA and CFA were analyzed via X-ray fluorescence (XRF), X-ray diffraction (XRD) and Inductive coupled plasma (ICP) to obtain a full chemical analysis of the samples, its crystallographic characteristics and a detailed count of the eight heavy metals contemplated in US Title 40 of the Code of Federal Regulations (40 CFR). The particle size distribution of IFA and CFA was also recorded. EPA's Toxicity Characteristic Leaching Procedure (TCLP) was followed to monitor the leachability of the contaminants before and after the activation. Also images obtained via Scanning Electron Microscopy (SEM), before and after the activation, are presented. Concrete made from IFA, CFA and IFA-CFA mixes was subjected to a full mechanical characterization; tests include compressive strength, flexural strength, elastic modulus, Poisson's ratio and setting time. The leachable heavy metal contents (except for Se) were below the maximum allowable limits and in many cases even below the reporting limit. The leachable Chromium was reduced from 0.153 down to 0.0045 mg/L, Arsenic from 0.256 down to 0.132 mg/L, Selenium from 1.05 down to 0.29 mg/L, Silver from 0.011 down to .001 mg/L, Barium from 2.06 down to 0.314 mg/L and Mercury from 0.007 down to 0.001 mg/L. Although the leachable Cd exhibited an increase from 0.49 up to 0.805 mg/L and Pd from 0.002 up to 0.029 mg/L, these were well below the maximum limits of 1.00 and 5.00 mg/L, respectively. PMID:22542857

Diaz-Loya, E Ivan; Allouche, Erez N; Eklund, Sven; Joshi, Anupam R; Kupwade-Patil, Kunal

2012-08-01

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Alkaline hydrothermal de-ashing and desulfurization of low quality coal and its application to hydrogen-rich gas generation  

International Nuclear Information System (INIS)

This paper describes experimental research and a fundamental study of alkaline hydrothermal treatment of high-sulfur, high-ash coal from Banten, Java-Indonesia. Experiments were carried out on a laboratory-scale 0.5 L batch reactor. The alkaline hydrothermal treatment gave upgraded clean coal with low sulfur content (about 0.3 wt.%) and low ash content (about 2.1 wt.%). A zero carbon dioxide and pure hydrogen gas were produced at 330 oC by introducing an alkali (sodium hydroxide, NaOH) to the hydrothermal treatment of raw coal. X-ray diffraction (XRD) and X-ray fluorescence (XRF) techniques were used to test for the removal or reduction of major inorganic elements in the coal, and changes in carbon-functional groups and their properties were determined by Fourier transform infrared spectroscopy (FTIR) and Carbon-13 of nuclear magnetic resonance (13C NMR) tests on the product of the hydrothermal upgrading and demineralization process.

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Environmental risks of farmed and barren alkaline coal ash landfills in Tuzla, Bosnia and Herzegovina  

International Nuclear Information System (INIS)

The disposal of coal combustion residues (CCR) has led to a significant consumption of land in the West Balkan region. In Tuzla (Bosnia and Herzegovina) we studied previously soil-covered (farmed) and barren CCR landfills including management practises, field ageing of CCR and the transfer of trace elements into crops, wild plants and wastewaters. Soil tillage resulted in mixing of cover soil with CCR. Medicago sativa showed very low Cu:Mo ratios (1.25) which may cause hypocuprosis in ruminants. Total loads of inorganic pollutants in the CCR transport water, but not pH (?12), were below regulatory limits of most EU countries. Arsenic concentrations in CCR transport water were -1 whereas reductive conditions in an abandoned landfill significantly enhanced concentrations in leachates (44 ?g l-1). The opposite pattern was found for Cr likely due to large initial leaching of CrVI. Public use of landfills, including farming, should be based on a prior risk assessment due to the heterogeneity of CCR. - Uncontrolled farming and tillage of previously soil-covered coal ash landfills resulted in exposure of ash on the surface

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Immobilization of B, F, Cr, and As in alkaline coal fly ash through an aging process with water.  

Science.gov (United States)

Fourteen different alkaline coal fly ashes (CFAs) were used for the experiment, in which each sample was mixed with water to be 28.6% of water content (wt/wt) and aged for 1-4 weeks at 10-30 °C. This simple treatment is advantageous for decreases in water-soluble B, F, Cr, and As. Compared to non-aged CFAs, their water-soluble fractions remained 0.56-88%, 21-85%, 0.37-93% and 2.6-88%, respectively, after aging for a week at 20 °C, although the amounts of Cr and As released from some CFA samples increased. Considering the significant decrease in elution of sulfate, Ca and Al after aging, the immobilization, namely prevention of toxic element elution, could be related to formation of secondary minerals such as portlandite, gypsum and ettringite. Immobilization of B and Cr tends to proceed preferentially under colder conditions. Aging at higher temperatures enhances the leachability of Cr in some CFA samples. Contrary to the behavior of B and Cr, water-soluble F effectively decreases under warmer conditions. PMID:25004853

Ogawa, Yasumasa; Sakakibara, Kento; Wang, Li; Suto, Koichi; Inoue, Chihiro

2014-10-01

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Ash Microspheres for Coal Burning  

International Science & Technology Center (ISTC)

Estimation of perspectives for ash microspheres production at coal burning thermal power stations , development of methods for their quality certification. Creation of a database for ash microspheres in Russian Federation.

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Measuring ash content of coal  

International Nuclear Information System (INIS)

An apparatus for measuring the ash content of coal is claimed. It comprises a means for irradiating a known quantity of coal in a transport container with a known dose of neutrons, a means for detecting ?-rays having a predetermined energy emitted by the irradiated coal, the ?-rays being indicative of the presence of an ash-forming element in the coal, a means for producing a signal related to the intensity of the ?-ray emission and a means responsive to the signal to provide an indication of the concentration of the ash-forming element in the coal

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Leaching characteristics of coal ash  

International Nuclear Information System (INIS)

In the thermal power station producing coal ash, the present trend is to dispose of fly and bottom ash in wet slurry form to a nearby ash pond site in which the ash settles and clear water is allowed to overflow from the ash pond. By virtue of the leaching characteristics of the ash, the heavy metals contained in the ash may gradually and slowly get leached from the ash and percolate to the nearby water bodies such as tube wells, ground waters, etc. In order to study the leaching characteristics of ash, experiments have been conducted in the laboratory by column and batch tests to study short, medium and long term leaching behaviour. The paper discusses the methodology adopted and gives the results obtained for different liquid-solid ratios by column and cascading methods including interpretation of the data. (author). 15 refs., 11 figs

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Adsorption of Crystal Violet Dye from Aqueous Solution onto Zeolites from Coal Fly and Bottom Ashes  

OpenAIRE

The adsorption of the cationic dye Crystal Violet (CV) over zeolites from coal fly ash (ZFA) and bottom ash (ZBA) was evaluated. The coal fly ash (CFA) and the coal bottom ash (CBA) used in the synthesis of the zeolites by alkaline hydrothermal treatment were collected in Jorge Lacerda coal-fired power plant located at Capivari de Baixo County, in Santa Catarina State, Brazil. The zeolitic materials were characterized predominantly as hydroxy-sodalite and X. The dye adsorption equilibrium was...

Tharcila Colachite Rodrigues Bertolini; Izidoro, Juliana C.; Magdalena, Carina P.; Fungaro, Denise A.

2013-01-01

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Physical, chemical and mineralogical characterisation of hydraulically disposed fine coal ash from SASOL Synfuels  

OpenAIRE

Coal serves as the primary energy source in most parts of the world. It is a fact that coal combustion yields enormous quantities of fly ash some of which are either hydraulically placed or dry dumped. The current study attempts to provide a comprehensive characterisation of a disused alkaline fine coal ash dam (FCAD) towards assessing environmental impact, rehabilitation and utilisation potential. Fine coal ash refers to a combination of approximately 83% power station fly ash and 17% gas...

Mahlaba, Jabulani Samuel; Kearsley, Elsabe P.; Kruger, Richard A.

2011-01-01

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Coal ash utilisation in India  

International Nuclear Information System (INIS)

Coal based thermal power stations have been the major source of power generation in our country in the past and would continue for decades to come. In India, thermal generation which contributes about 72% of the overall power generation of 2,45,000 MU (1989-90) is the main source of power and mainly based on coal firing. Total ash generation in India presently is to the tune of 38 million tonnes per annum. India is fourth in the world as far as coal ash generation is concerned. USSR is first, (100 million tonnes), then come USA (45 million tonnes) and China (41 million tonnes). The basic problem of thermal power station fired with high ash content coal is the generation of huge quantity of coal ash which would pose serious environmental and other related problems. The present paper analyses the extensive scope of utilisation of coal ash and enlightens the strategies to be adopted to overcome the related problems for proper utilisation of coal ash. (author). 9 tabs

12

Classification of pulverized coal ash  

International Nuclear Information System (INIS)

The leachability of fifty different pulverized coal ashes from utilities in the Netherlands, Federal Republic of Germany and Belgium has been studied. Five different ashes were analyzed according to the complete standard leaching test and the results were published earlier. The examination of a wide variety of ashes under a wide range of pH and Liquid to Solid ratio (LS) conditions creates the possibility of identifying systematic trends in fly ash leaching behaviour and to identify the mechanisms controlling release. 16 figs., 2 tabs., 3 app., 25 refs

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Sorption of aqueous phosphorus onto bituminous and lignitous coal ashes  

International Nuclear Information System (INIS)

Aiming at the development of a phosphorus removal technology for waste water, phosphate (PO43-) retention behavior of bituminous and lignitous coal ashes was investigated using a batch reactor. Ash samples, including fresh and weathered fly and bottom ashes, were studied for their sorption isotherms and reversibility. Fly ashes had a much higher phosphate retention capacity (4000-30,000 mg P/kg) than bottom ashes (15-600 mg P/kg). Lignitous coal ashes were more capable of retaining phosphate than bituminous coal ashes. The retention process was largely irreversible, and the irreversibility increased with the increase in the retention capacity. Weathering enlarged the retention capacity of the bituminous bottom ash, but substantially lowered that of the fly ash, likely due to the difference in the weather-induced changes between the fly and bottom ashes. Sorption isotherms of fly ashes were found to be adequately represented by the Langmuir model while those of bottom ashes fitted better to the Freundlich model. Concentrations of Ca2+ and PO43- in the aqueous phase were measured at the end of sorption and desorption experiments, and were compared with solubilities of three calcium phosphate minerals. The aqueous solutions were saturated or super-saturated with respect to tricalcium phosphate (Ca3(PO4)2) and hydroxyapatite (Ca5(PO4)3OH), and slightly sub>4)3OH), and slightly under-saturated with respect to amorphous calcium phosphate. It is concluded that precipitation of calcium phosphate is the predominant mechanism for phosphate retention by coal ash under the conditions studied. There is a strong and positive correlation between alkalinity and phosphate sorption capacity. Consequently, acid neutralization capacity (ANC) can be used as an indicator of phosphate sorption capacity of coal ashes

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Chemical composition of coal and fly ash  

International Nuclear Information System (INIS)

A method for the analysis of the inorganic constituents of coal has been developed. Thermal neutron activation analysis and Ge(Li)?-spectrometry was used to determine 43 elements simultaneously. Oxygen and silicon were simultaneously determined after a single irradiation with 14 MeV neutrons, producing respectively the isotopes 16N and 28Al. Lead was determined by atomic absorption spectrometry. The accuracy of the methods was investigated by analysing NBS coal and fly ash reference materials. The methods described were used in the analysis of a large number of coal, coal ash and fly ash samples. The elements in coal were divided into a mineral and an organic fraction, based on the correlation between the concentrations in the coal and the ash content of coal. The fly ash emissions from combustion of coal were studied in a large and a small heating facility. Based on their mass size distributions, the elements could be divided into 3 groups: a first group associated with large particles and depleted in fly ash relative to the coal composition, a second group associated with small particles and enriched in fly ash, and a third group with intermediate behaviour. (author)

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The impacts of coal refuse/fly ash bulk bends on water quality and plant growth  

Energy Technology Data Exchange (ETDEWEB)

There is considerable interest in the beneficial reuse of coal fly ash as a soil amendment on coal refuse piles. One method of application would be to blend the coal refuse and the fly ash before deposition in a refuse pile. A field experiment was initiated to measure the effects of bulk blending fly ash with coal refuse on water quality and plant growth parameters. Fly ash (class F) from three sources were used in the experiment. Two of the fly ashes were acidic and the third was alkaline. Trenches were excavated in a coal refuse pile to a depth of 2 m and the refuse was blended with fly ash and then returned to the trench. In other plots the ash was applied as a surface amendment. A treatment of a bulk blend of 5% (w/w) rock phosphate was also included in the experiment. Large volume lysimeters were installed in some trenches to collect the leachates. The fly ash treatments appear to improve the quality of the leachates when compared to the leachates from the untreated plots. The fly ash amended treatments have lower leachate concentrations of Fe and Al. Initially the fly ash treatments showed high levels of leachate B, however those levels have decreased with time. Millet (Setaria italica) yields from the first year of the experiment were highest n the alkaline fly ash and rock phosphate blended plots. In the second growing season, the two bulk blends with alkaline fly ash had the highest yields. In the third growing season all treatments had higher yield levels than the untreated control plots. The positive effects of the fly ash on leachate quality were attributed to the alkalinity of the ash, and the increase in yield was attributed to the increases in water holding capacity due to fly ash treatments.

Stewar, B.R.; Daniels, W.L. [Virginia Polytechnic Institute and State Univ., Blacksburg, VA (United States)

1995-09-01

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Coal and fly ash-problem  

International Nuclear Information System (INIS)

Indian thermal power plants use coal carrying as high as 30 to 40% of ash. As larger and larger amounts of coal are going to be used to meet the increasing demand for electrical energy, large amount of fly ash is bound to be produced as solid waste. Its disposal gives rise to adverse environmental impacts such as contamination of surface and subsurface water with toxic heavy metals which are constituents of coal, loss of soil fertility around plant sites and siltation of natural drainage system. For large scale utilization of ash in a proper manner, it is necessary to study physico-chemical properties of ash, mineralogy of coal used in power plants and size distribution of ash grains. Dependence of physico-chemical properties of ash on mineral constituents of coal and mechanism of burning is discussed. Enrichment of toxic metals in ash and presence of halogens in Indian coal and their likely environmental impacts are also pointed out. (M.G.B.). 17 refs., 5 tabs., 3 figs

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Microbial responses to coal fly ash under field conditions  

Energy Technology Data Exchange (ETDEWEB)

Coal fly ash may be a valuable soil amendment because it contains plant nutrients and liming agents and has a silty texture that can improve the water-holding capacities of sandy, drought-prone soils. Short-term laboratory studies have indicated that addition of unweathered fly ash to soil can stress microbial populations and their activities, but effects of fly ash addition at the field scale are not known. In this study, field plots received 0 or 505 Mg fly ash ha{sup -1} (incorporated by conventional tillage to a depth of 40 cm) and were subsequently cropped to a fallow-corn (Zea mays L.)-wheat (Triticum aestivum L.) rotation or continuous fescue (Festuca arundinacea Schreb.). Twenty months later, during the wheat phase of the rotation, the plots were sampled (0-15 cm) and assayed for activity of soil enzymes (dehydrogenase, alkaline phosphatase, arylsulfatase, and denitrifying enzymes); numbers of aerobic heterotrophs, ammonium oxidizers, denitrifiers, and bradyrhizobia; and N mineralization, nitrification, and denitrification potentials. Nitrification potentials doubled in fly ash-amended soils, and numbers of denitrifiers were 200-fold higher in fescue-cropped, fly ash-amended soils relative to fescue-cropped, non-amended soils. No other large differences in microbial populations or activities were found. The lack of detrimental effects on microorganisms in the field was possibly due to reductions in fly ash`s soluble salt and trace element concentrations with time, the mild alkalinity of the fly ash used in this study, and the positive responses of crops to fly ash amendment. 23 refs., 3 tabs.

Schutter, M.E.; Fuhrmann, J.J. [Oregon State University, Corvallis, OR (United States). Dept. of Crop and Soil Science

1999-03-01

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Elemental analysis of coal and coal ASH by PIXE technique  

International Nuclear Information System (INIS)

Coal and coal ash samples were characterized by particle induced X-ray emission spectroscopic technique. Sixteen elements, namely K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, As, Rb, Sr, Y and Pb were quantified in this study. Elements like K, Ca, Ti and Fe were present as major elements, whereas, other elements like V, Cr, Mn, Co, Ni, Cu, Zn, As, Se, Rb, Sr and Pb were present in trace level. The enrichment ratio of different ash samples with respect to coal were also estimated and discussed. - Highlights: ? Elemental analysis of coal and coal ash including pond ash is the first of its kind. ? The enrichment ratio has been exclusively explained in the study. ? Non-destructive PIXE analysis has been employed in this study and both major and trace elements has been estimated.

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Effect of coal blending on the leaching characteristics of arsenic and selenium in fly ash from fluidized bed coal combustion  

Energy Technology Data Exchange (ETDEWEB)

The capture ability of fly ash to arsenic (As) and selenium (Se) was investigated through the combustion of two single bituminous coals A and B and their mixture (blending ratio of 1:1, wt/wt) in a lab-scale fluidized bed reactor. The leaching characteristics of As and Se in corresponding fly ash were also conducted according to Japanese Industrial Standard (JIS). Speciation of As and Se during fly ash leaching test were predicted from the perspective of thermodynamic equilibrium. The results indicate that, combustion of coal B, containing abundant calcium, possesses a higher capture ability of As and Se than that of coal A through possible chemical reaction between As/Se with CaO. Leaching behavior of As and Se from fly ash is strongly dependent on the pH of the leachate. Free calcium in fly ash generates an alkaline leachate during leaching test and subsequently reduces As and Se leaching, which cause the leaching ratio of As and Se in fly ash derived from the combustion of coal B was much lower, relative to that in coal A. Combustion of blending coal promotes the overall capture ability of the fly ash to As/Se and reduces their leaching from fly ash through the synergy of free CaO between this two kind of fly ash.

Jiao, F.; Yamada, N.; Sato, A.; Ninomiya, Yoshihiko [Chubu Univ., Aichi (Japan). Dept. of Applied Chemistry; Zhang, L. [Monash Univ., Clayton, VIC (Australia). Dept. of Chemical Engineering

2013-07-01

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Measurement of the ash content of coal  

International Nuclear Information System (INIS)

A monitor for determining the ash content of coal in wagons consisting of a structure including means for irradiating each wagon as it passes the structure with a known dose of neutrons, means for detecting and measuring the intensities of ?-rays emitted by ash-forming elements in the coal, and means for providing as indication of the concentration of the ash-forming elements. There also are included interlocks for ensuring that the neutron source is only operated when a loaded wagon is in the appropiate position

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COMPARISON OF LEACHABLE TRACE ELEMENT LEVELS IN COAL GASIFIER ASH WITH LEVELS IN POWER PLANT ASH  

Science.gov (United States)

The paper gives results of a comparison of the levels of 14 trace elements in leachates from three types of ash of a common origin coal. The 1-year study was conducted at the Kosovo plant in Obilic, Yugoslavia, comparing coal gasifier ash with fly ash and bottom ash from a coal-f...

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Mutagenicity and genotoxicity of coal fly ash water leachate  

Energy Technology Data Exchange (ETDEWEB)

Fly ash is a by-product of coal-fired electricity generation plants. The prevalent practice of disposal is as slurry of ash and water to storage or ash ponds located near power stations. This has lain to waste thousands of hectares of land all over the world. Since leaching is often the cause of off-site contamination and pathway of introduction into the human environment, a study on the genotoxic effects of fly ash leachate is essential. Leachate prepared from the fly ash sample was analyzed for metal content, and tested for mutagenicity and genotoxicity. Analyses of metals show predominance of the metals - sodium, silicon, potassium, calcium, magnesium, iron, manganese, zinc, and sulphate. The Ames Salmonella mutagenicity assay, a short-term bacterial reverse mutation assay, was conducted on two-tester strains of Salmonella typhimurium strains TA97a and TA102. For genotoxicity, the alkaline version of comet assay on fly ash leachate was carried in vitro on human blood cells and in vivo on Nicotiana plants. The leachate was directly mutagenic and induced significantconcentration-dependent increases in DNA damage in whole blood cells, lymphocytes, and in Nicotiana plants. The comet parameters show increases in tail DNA percentage (%), tail length (mu m), and olive tail moment (arbitrary units). Our results indicate that leachate from fly ash dumpsites has the genotoxic potential and may lead to adverse effects on vegetation and on the health of exposed human populations.

Chakraborty, R.; Mukherjee, A. [University of Calcutta, Calcutta (India). Dept. of Botany

2009-03-15

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Classification of coal by trace analysis using INAA-clusteranalysis and leaching of precipitator ash  

International Nuclear Information System (INIS)

In The Netherlands the coal used for energy production is imported from many different countries. This implies a great variability of the (trace) element levels in the ash produced which in turn has implications for disposal and the preferred application in industry. To get hold of this variability in precipitator ashes obtained from coals of different origin a classification of coal was performed with clusteranalysis using the elemental composition (CLUSTAN-1C package). In addition to the measurement of elemental concentrations in coal and ash, leaching experiments were performed with precipitator ash. Elements which are leached appreciably are the halogens, SO42-, Mo, W, Cd and Hg. Arsenic and selenium are hardly leached from the alkaline ash studied

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Acid mine drainage mitigation using bulk blended fly ash/coal refuse mixtures: Column study results  

International Nuclear Information System (INIS)

Many Appalachian coal refuse materials contain significant amounts of pyritic-S and are likely to produce acid mine drainage (AMD). A column technique was designed and implemented to evaluate the effects of various AMD mitigation treatments including fly ash, topsoil, lime, and rock-P. Two types of fly ash were tested, one at four rates of application, the other at two rates. Conventional lime plus topsoil, lime without topsoil, topsoil only, topsoil with fly ash, rock-P, rock-P plus topsoil, and rock-P plus fly ash were also evaluated and compared with pure refuse controls. The drainage from the unamended columns rapidly dropped to pH 2 with very high levels of Fe and Mn. Alkaline fly ash dramatically reduced drainage Fe concentrations as well as Mn when compared with untreated refuse. The rock-P treatment also improved drainage but eventually lost its mitigation capability. Leachate B concentrations were initially high for some of the ash columns, but decreased over time, while the unamended refuse B levels increased with time. Combined treatments of phosphate/ash, ash/topsoil, and pure refuse with topsoil were intermediate between the alkaline ash/lime treatments and unamended refuse in drainage quality. With further analysis, fly ash may prove to be a viable alternative to conventional topsoiling/lime treatments to control AMD if adequate alkalinity is present in the ash/refuse mixture. If fly ash alkalinity is inadequate to balance potential acidity, accelerated to balance potential acidity, accelerated leaching of ash bound metals may occur. Therefore, the uncontrolled disposal of fly ash within coal refuse disposal facilities should be discouraged unless acid/base balance concerns are met

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CHARACTERIZATION OF ASH FROM COAL-FIRED POWER PLANTS  

Science.gov (United States)

The report summarizes existing data on the chemical and physical characteristics of ashes produced by the burning of coal in steam-electric generating plants. It summarizes several recent coal or ash characterization studies, emphasizing the elemental chemical composition, partic...

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Sensing the ash content of coal  

International Nuclear Information System (INIS)

The ash content of a coal sample is sensed by bombarding it with primary radiation comprising at least two spectrums of energies (46 KeV and 9-17 KeV ? and X-rays) to cause radiative reactions in the coal, sensing the secondary radiation generated by the radiative reactions caused by one of the two spectrums of energies (46 KeV), sensing the secondary radiations at a characteristic fluorescent energy of at least one element (e.g. iron) in the coal sample, the characteristic fluorescent energy being excited by the other of the two spectrums of energies (9-17 KeV), and using the sensed secondary radiations to determine the ash content of the coal. The ? and X-rays may come from a single lead 210 source or from separate sources. (author)

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Synthesis of zeolites from coal fly ash  

OpenAIRE

The combustion of coal in power stations produces large quantities of coal fly ash (CFA). At present, in the Netherlands, this combustion residue is almost completely used for the production of bUilding materials. Expectations that the present use of CFA would be affected in the near future by legal and technical developments and by competition with other residual materials, started an interest in new possible applications. One of these is the synthesis of zeolites, the subject...

Hollman, G. G.

1999-01-01

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Illinois basin coal fly ashes. 2. Equilibria relationships and qualitative modeling of ash-water reactions  

Science.gov (United States)

Alkaline and acidic Illinois Basin coal fly ash samples were each mixed with deionized water and equilibrated for about 140 days to simulate ash ponding environments. Common to both equilibrated solutions, anhydrite solubility dominated Ca2+ activities, and Al3+ activities were in equilibrium with both matrix mullite and insoluble aluminum hydroxide phases. Aqueous silica activities were controlled by both mullite and matrix silicates. The pH of the extract of the acidic fly ash was 4.1 after 24 h but increased to a pH value of 6.4 as the H2SO4, assumed to be adsorbed to the particle surfaces, was exhausted by the dissolution of matrix iron oxides and aluminosilicates. The activities of aqueous Al3+ and iron, initially at high levels during the early stages of equilibration, decreased to below analytical detection limits as the result of the formation of insoluble Fe and Al hydroxide phases. The pH of the extract of the alkaline fly ash remained above a pH value of 10 during the entire equilibration interval as a result of the hydrolysis of matrix oxides. As with the acidic system, Al3+ activities were controlled by amorphous aluminum hydroxide phases that began to form after about 7 days of equilibration. The proposed mechanisms and their interrelations are discussed in addition to the solubility diagrams used to deduce these relationships. ?? 1984 American Chemical Society.

Roy, W.R.; Griffin, R.A.

1984-01-01

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Pure zeolite synthesis from silica extracted from coal fly ashes  

Energy Technology Data Exchange (ETDEWEB)

Pure zeolites can be synthesised from silica extracted from fly ash by alkaline leaching. If the process is optimised the solid residue arising from this extraction may also contain a relatively high content of zeolitic material mixed with residual fly ash components. Both the pure and the impure zeolitic material have a high potential for application in waste-water and flue gas-cleaning technologies. The silica extraction potential of 23 European coal fly ashes covering most of the possible fly ash types is investigated in this study. Optimisation of leaching processes, by varying temperature, time and alkali/fly ash rates, permitted extraction yields up to 140 g of SiO{sub 2} per kg using a single step process, but the extraction yields may reach up to 210 g kg{sup -1} by applying thermal pre-treatments prior to the extraction. The solid residue arising from the silica extraction experiments shows a high NaP1 zeolite content. A high Si/Al ratio of the glass matrix, the occurrence of easily soluble silica phases in the original fly ash and a high reactive surface area were found to be the major parameters influencing silica extraction. High purity 4A and X zeolitic material was obtained by combining the silica extracts from the Meirama fly ash and a waste solution from the Al-anodising industry. The results allowed conversion of the silica extraction yields to an equivalent 630 g of pure 4A-X zeolite per kg of fly ash with a cation exchange capacity of 4.7 meq g{sup -1}.

Moreno, N.; Querol, X.; Plana, F.; Andres, J.M.; Janssen, M.; Nugteren, H. [CSIC, Barcelona (Spain). Inst. Earth Science ' Jaume Almera'

2002-07-01

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Physical, chemical and mineralogical characterisation of hydraulically disposed fine coal ash from SASOL Synfuels  

Energy Technology Data Exchange (ETDEWEB)

Coal serves as the primary energy source in most parts of the world. It is a fact that coal combustion yields enormous quantities of fly ash some of which are either hydraulically placed or dry dumped. The current study attempts to provide a comprehensive characterisation of a disused alkaline fine coal ash dam (FCAD) towards assessing environmental impact, rehabilitation and utilisation potential. Fine coal ash refers to a combination of approximately 83% power station fly ash and 17% gasification and bottom ash fines (particles {lt}250 {mu}m) at SASOL Synfuels. The hydration products found in Weathered Fine Coal Ash (WFCA) using X-ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC) are analcime, calcite, C-S-H gel, ettringite, hydrated gehlenite (Strtlingite), magnetite, periclase, pyrrhotite and sillimanite. High resolution Scanning Electron Microscope (SEM) results provide additional proof that hydration products are present in WFCA. No indication of appreciable leaching was given by X-ray Fluorescence (XRF) results except calcium and silicon. Thus evidence exists that pollutants from saline brines are immobilised in WFCA and an insight of reaction kinetics was obtained. High content of amorphous phase and lack of alteration in some geotechnical properties suggest that WFCA can be reutilised with lime addition to increase alkalinity and activate pozzolanic reactions. 48 refs., 18 figs., 4 tabs.

Jabulani S. Mahlaba; Elsabe P. Kearsley; Richard A. Kruger [University of Pretoria, Pretoria (South Africa). Civil Engineering

2011-07-15

31

Effects of pulverized coal fly-ash addition as a wet-end filler in papermaking  

Energy Technology Data Exchange (ETDEWEB)

This experimental study is based on the innovative idea of using pulverized coal fly ash as a wet-end filler in papermaking. This is the first evaluation of the possible use of fly ash in the paper industry. Coal-based thermal power plants throughout the world are generating fly ash as a solid waste product. The constituents of fly ash can be used effectively in papermaking. Fly ash has a wide variation in particle size, which ranges from a few micrometers to one hundred micrometers. Fly ash acts as an inert material in acidic, neutral, and alkaline papermaking processes. Its physical properties such as bulk density (800-980 kg/m{sup 3}), porosity (45%-57%), and surface area (0.138-2.3076 m{sup 2}/g) make it suitable for use as a paper filler. Fly ash obtained from thermal power plants using pulverized coal was fractionated by a vibratory-sieve stack. The fine fraction with a particle size below 38 micrometers was used to study its effect on the important mechanical-strength and optical properties of paper. The effects of fly-ash addition on these properties were compared with those of kaolin clay. Paper opacity was found to be much higher with fly ash as a filler, whereas brightness decreased as the filler percentage increased Mechanical strength properties of the paper samples with fly ash as filler were superior to those with kaolin clay.

Sinha, A.S.K. [SLIET, Longowal (India). Dept. of Chemical Technology

2008-09-15

32

pH-dependent leaching of dump coal ash - retrospective environmental analysis  

Energy Technology Data Exchange (ETDEWEB)

Trace and major elements in coal ash particles from dump of 'Nikola Tesla A' power plant in Obrenovac near Belgrade (Serbia) can cause pollution, due to leaching by atmospheric and surface waters. In order to assess this leaching potential, dump ash samples were subjected to extraction with solutions of decreasing pH values (8.50, 7.00, 5.50, and 4.00), imitating the reactions of the alkaline ash particles with the possible alkaline, neutral, and acidic (e.g., acid rain) waters. The most recently deposited ash represents the greatest environmental threat, while 'aged' ash, because of permanent leaching on the dump, was shown to have already lost this pollution potential. On the basis of the determined leachability, it was possible to perform an estimation of the acidity of the regional rainfalls in the last decades.

Popovic, A.; Djordjevic, D. [University of Belgrade, Belgrade (Serbia). Dept. of Chemistry

2009-07-01

33

Radioactivity of coals and fly ashes  

Energy Technology Data Exchange (ETDEWEB)

The level and the behavior of the naturally occurring primordial radionuclides U-238, Ra-226, Pb-210, Th-232, Ra-228 and K-40 in coals and fly ashes are described. The activity concentrations of the examined coals and originated from coal mines in Greece ranged from 117 to 435 Bq.kg{sup -1} for U-238, from 44 to 255 Bq.kg{sup -1} for Ra-226, from 59 to 205 Bq.kg{sup -1} for Pb-210, from 9 to 41 Bq.kg{sup -1} for Ra-228 and from 59 to 227 Bq.kg{sup -1} for K-40. These levels are comparable to those appeared in coals of different countries worldwide. The activity concentrations of the examined fly ashes and produced in coal-fired power plants in Greece ranged from 263 to 950 Bq.kg{sup -1} for U-238, from 142 to 605 Bq.kg{sup -1} for Ra-226, from 133 to 428 Bq.kg{sup -1} for Pb-210, from 27 to 68 Bq.kg{sup -1} for Ra-228 and from 204 to 382 Bq.kg{sup -1} for K-40. The results showed that there is an enrichment of the radionuclides in fly ash relative to the input coal during the combustion process. The enrichment factors (EF) ranged from 0.60 to 0.76 for U-238, from 0.69 to 1.07 for Ra-226, from 0.57 to 0.75 for Pb-210, from 0.86 to 1.11 for Ra-228 and from 0.95 to 1.10 for K-40.

Papastefanou, C. [Aristotle University Thessaloniki, Thessaloniki (Greece)

2008-01-15

34

Studies on the phase mineralogy and leaching characteristics of coal fly ash  

International Nuclear Information System (INIS)

The phase mineralogy and leaching characteristics of some Indian coal fly ashes were studied to assess their safe disposal in abandoned coal mines. Since, fly ash contains a number of toxic trace elements, the leaching of fly ash was tested using strong acid/alkali solutions and distilled water under different conditions (solid-liquid ratio, leaching time, pH) in the temperature range of 30-100 degree C. It was found that the concentration of various metals in leachates depends on their chemical nature, association with mineral phases of ash and follows the almost similar concentration profile to that of iron, especially in acidic medium. The distribution of toxic trace elements in fly ash and their leachability were found to depend on the amount of unburnt carbon and iron in fly ash. In alkaline medium, leaching of iron and toxic trace elements (except As) from fly ash was very negligible. Hence, alkali treatment of coal fly ash is desirable for its safe use in refilling of coal mines. 27 refs., 14 figs., 8 tabs

35

Coal Ash Corrosion Resistant Materials Testing  

Energy Technology Data Exchange (ETDEWEB)

In April 1999, three identical superheater test sections were installed into the Niles Unit No.1 for the purpose of testing and ranking the coal ash corrosion resistance of candidate superheater alloys. The Niles boiler burns high sulfur coal (3% to 3.5%) that has a reasonably high alkali content, thus the constituents necessary for coal ash corrosion are present in the ash. The test sections were controlled to operate with an average surface metal temperature from approximately 1060 F to 1210 F which was well within the temperature range over which coal ash corrosion occurs. Thus, this combination of aggressive environment and high temperature was appropriate for testing the performance of candidate corrosion-resistant tube materials. Analyses of the deposit and scale confirmed that the aggressive alkali-iron-trisulfate constituent was present at the metal surface and active in tube metal wastage. The test sections were constructed so that the response of twelve different candidate tube and/or coating materials could be studied. The plan was to remove and evaluate one of the three test sections at time intervals of 1 year, 3 years, and 5 years. This would permit an assessment of performance of the candidate materials as a function of time. This report provides the results of the evaluation of Test Section C, including the samples that remained in the Test Section for the full exposure period as well as those that were removed early. The analysis of Test Section C followed much the same protocol that was employed in the assessment of Test Section A. Again, the focus was on determining and documenting the relative corrosion rates of the candidate materials. The detailed results of the investigation are included in this report as a series of twelve appendices. Each appendix is devoted to the performance of one of the candidate alloys. The table below summarizes metal loss rate for the worst case sample of each of the candidate materials for both Test Sections A and C. The body of this report compares these for all of the samples in the test section. The 'Coal Ash Corrosion Resistant Materials Testing Program' is being conducted by The Babcock & Wilcox Company (B&W), the U.S. Department of Energy (DOE) and the Ohio Coal Development Office (OCDO) at Reliant Energy's Niles plant in Niles, Ohio to provide full-scale, in-situ testing of recently developed boiler superheater materials. Fireside corrosion is a key issue for improving efficiency of new coal fired power plants and improving service life in existing plants. In November 1998, B&W began development of a system to permit testing of advanced tube materials at metal temperatures typical of advanced supercritical steam temperatures (1100 F and higher) in a boiler exhibiting coal ash corrosive conditions. Several materials producers including Oak Ridge National Laboratory (ORNL) contributed advanced materials to the project. In the spring of 1999 a system consisting of three identical sections, each containing multiple segments of twelve different materials, was installed. The sections are cooled by reheat steam, and are located just above the furnace entrance in Niles Unit No.1, a 110 MWe unit firing high sulfur Ohio coal. In November 2001 the first section was removed for thorough metallurgical evaluation after 29 months of operation. The second section was removed in August of 2003. Its evaluation has been completed and is the subject of this report. The final section remains in service and is expected to be removed in the spring of 2005. This paper describes the program; its importance, the design, fabrication, installation and operation of the test system, materials utilized, and experience to date. This report briefly reviews the results of the evaluation of the first section and then presents the results of the evaluation of the second section.

D. K. McDonald; P. L. Daniel; D. J. DeVault

2003-08-31

36

Mechanical Properties of Composite Material Using Coal Ash and Clay  

Science.gov (United States)

Coal ash is industry waste exhausted lots of amount by electric power plant. The particle sizes of coal ash, especially coal fly ash are very fine, and the chemical component are extremely resemble with Okinawa-Kucha clay. From the point of view that clay is composed of particles of micro meter size in diameter, we should try the application for fabrication of composite material using coal fly ash and clay. The comparison of the mechanical properties of composite material using coal fly ash and clay were performed during electric furnace burning and spark plasma sintering. As a result, the bending strength of composite material containing the coal ash 10% and fired at 1423K using the electric furnace after press forming at 30 MPa showed the highest value of 47 MPa. This phenomenon suggests a reinforcement role of coal ash particles to clay base material. In spark plasma sintering process, the bending strength of the composite material containing the clay 5-10% to fly ash base material fired at 1473K and pressured at 20 MPa showed the highest value of 88 MPa. This result indicates a binder effect of clay according to the liquid phase sintering of melted clay surrounding around coal fly ash particles surface.

Fukumoto, Isao; Kanda, Yasuyuki

37

The production of artificial soil mix from coal fly ash and sewage sludge  

Energy Technology Data Exchange (ETDEWEB)

The scarcity of land in Hong Kong makes landfilling an unattractive means for the disposal of sewage sludge and coal fly ash. Therefore, reutilisation of these solid wastes might ease the disposal problems. A glasshouse pot leaching study was performed to evaluate the feasibility of using alkaline fly ash as a stabilisation agent for sewage sludge and the final production being used as a potting medium. Sludge was amended with ash at 0, 5, 10, 35 and 50% (w/w). Each mixture was then mixed with a loamy soil (1:1 v/v) and leached with 600 mL of deionized water prior to plant growth experiment using Agropyron elongatum (Tall wheat grass). Soil pH and electrical conductivity following leaching increased consistently with an increase in ash amendment, from 6.3 to 8.2 and 1.6 to 2.3 dS m{sup -1} respectively. Pots amended with 35% ash showed a significant reduction in Zn, Cu and Cd availability but an increase in B contents. The total dry weight yields of ash amended pots were significantly increased as compared to the control without ash amendment. Addition of ash also significantly reduced the uptake of Zn, Cu and Mn but increased shoot B contents. However, the high tissue B contents had no adverse effect on plant growth. The experimental results affirm that alkaline ash is effective in reducing the metal availability of sludge, and acts as a good stabilisation agent for sewage sludge.

Wong, J.W.C. [Hong Kong Baptist University, Kowloon (Hong Kong). Dept. of Biology

1995-08-01

38

Ash transformation during co-firing coal and straw  

DEFF Research Database (Denmark)

Co-firing straw with coal in pulverized fuel boilers can cause problems related to fly ash utilization, deposit formation, corrosion and SCR catalyst deactivation due to the high contents of Cl and K in the ash. To investigate the interaction between coal and straw ash and the effect of coal quality on fly ash and deposit properties, straw was co-fired with three kinds of coal in an entrained flow reactor. The compositions of the produced ashes were compared to the available literature data to find suitable scaling parameters that can be used to predict the composition of ash from straw and coal co-firing. Reasonable agreement in fly ash compositions regarding total K and fraction of water soluble K was obtained between co-firing in an entrained flow reactor and full-scale plants. Capture of potassium and subsequent release of HCl can be achieved by sulphation with SO2 and more importantly, by reaction with Al and Si in the fly ash. About 70-80% K in the fly ash appears as alumina silicates while the remainder K is mainly present as sulphate. Lignite/straw co-firing produces fly ash with relatively high Cl content. This is probably because of the high content of calcium and magnesium in lignite reacts with silica so it is not available for reaction with potassium chloride. Reduction of Cl and increase of S in the deposits compared to the fly ashes could be attributed to sulphation of the deposits.

Zheng, Yuanjing; Jensen, Peter Arendt

2007-01-01

39

Norm in coal, fly ash and cement  

Energy Technology Data Exchange (ETDEWEB)

Coal is technologically important materials being used for power generation and its cinder (fly ash) is used in manufacturing of bricks, sheets, cement, land filling etc. {sup 222}Rn (radon) and its daughters are the most important radioactive and potentially hazardous elements, which are released in the environment from the naturally occurring radioactive material (NORM) present in coal, fly ash and cement. Thus it is very important to carry out radioactivity measurements in coal, fly ash and cement from the health and hygiene point of view. Samples of coal and fly ash from different thermal power stations in northern India and various fly ash using establishments and commercially available cement samples (O.P.C. and P.P.C.) were collected and analyzed for radon concentration and exhalation rates. For the measurements, alpha sensitive LR-115 type II plastic track detectors were used. The radon concentration varied from 147 Bq/m{sup 3} to 443 Bq/m{sup 3}, the radium concentration varied from 1.5 to 4.5 Bq/kg and radon exhalation rate varied from 11.8 mBq.kg{sup -1}.h{sup -1} to 35.7 mBq.kg{sup -1}.h{sup -1} for mass exhalation rate and from 104.5 mBq.m{sup -2}.h{sup -1} to 314.8 mBq.m{sup -2}.h{sup -1} for surface exhalation rate in coal samples. The radon concentration varied from 214 Bq/m{sup 3} to 590 Bq/m{sup 3}, the radium concentration varied from 1.0 to 2.7 Bq/kg and radon exhalation rate varied from 7.8 mBq.kg{sup -1}.h{sup -1} to 21.6 mBq.kg{sup -1}.h{sup -1} for mass exhalation rate and from 138 mBq m{sup -2}h{sup -1} to 380.6 mBq.m{sup -2}.h{sup -1} for surface exhalation rate in fly ash samples. The radon concentration varied from 157.62 Bq/m{sup 3} to 1810.48 Bq/m{sup 3}, the radium concentration varied from 0.76 Bq/kg to 8.73 Bq/kg and radon exhalation rate varied from 6.07 mBq.kg{sup -1}.hr{sup -1} to 69.81 mBq.kg{sup -1}.hr{sup -1} for mass exhalation rate and from 107.10 mBq.m{sup -2}.hr{sup -1} to 1230.21 mBq.m{sup -2}.hr{sup -1} for surface exhalation rate in different cement samples. The values were found higher in P.P.C. samples than in O.P.C. samples. (authors)

Kant, K. [K.L.Mehta Dayanand College for Women, Dept. of Physics, Faridabad (India); Upadhyay, S.B. [B.S.A. College, Dept. of Physics, Mathura - 281 001 (U.P.), Mathura (India); Sharma, G.S. [B.S.A. College, Mathura - 281 001 (U.P.), Dept. of Physics, Mathura (India)

2006-07-01

40

Investigations on Cr mobility from coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

Coal fly ash, which is a source of metals emission to environment, was researched. Investigations on Cr chemical fractions and their environmental mobility in ash-solution system were carried out. In order to obtain results repeatedly, the conditions of sequential extraction of Cr from coal fly ash were optimized. It was found that Cr in coal fly ash occurs in the following fractions (mg kg{sup -1}): exchangeable (2.5), associated to carbonates (4.0), associated to organic matter and sulfides (8.5), associated to Fe-Mn oxides (16.0), and residual (41.6). Mobility fractions of Cr contain 8.2% of its total concentration in the fly ash in environmental conditions. The obtained results indicate that coal fly ash is a source of environmental contamination by Cr especially in soils where its utilization is inadequate. 24 refs., 2 figs., 6 tabs.

Eleonora Soco; Jan Kalembkiewicz [Rzeszow University of Technology, Rzeszow (Poland). Department of Inorganic and Analytical Chemistry

2009-08-15

41

Ash concentration in hard coal and its natural gamma radioactivity  

International Nuclear Information System (INIS)

The subject mater of this paper is correlation between ash content of hard coal and its radioactivity for selected mines in Upper Silesian Coal Basin (USCB), Poland. In this region both the inorganic part of coal and waste rock (clays, shales, mudstones) contain significant amounts of natural radioactive elements (nuclides) whereas the organic part of coal is practically deprived of them. Therefore, almost the entire natural radioactivity of coal is related to its ash content and, consequently, there should be a correlation between these values. On the other hand, coal deposits, which were formed in different geological conditions, may differ by their mineralogical compositions, both of its inorganic part and waste rock. This results in occurrence of regional properties of hard coal; also parameters describing natural radioactivity are differentiated regionally. The authors described quantitatively the correlation between ash content in coal and its radioactivity. (author)

42

Influence of sewage sludge addition on coal ash fusion temperatures  

Energy Technology Data Exchange (ETDEWEB)

The ash fusion characteristics of three types of bituminous coal (A, B, and C), one type of sewage sludge (W), and the corresponding coal-sewage sludge blends (10 and 50 wt % of sludge) were studied. The ash fusibility temperatures of samples in oxidizing atmosphere were measured, and their chemical and mineralogical compositions were determined. The addition of sludge to coal in certain proportions produces blends whose ashes have lower fusibility temperatures than those of coal and sludge. This is related to the differences in chemical composition and modes of elemental combination in both types of materials. The main differences are associated to the elements P, Fe, and Ca. As the sludge is much richer in Ca than the coals, the compositions of the blend ashes pass through low-temperature eutectic regions of the ternary phase diagrams SiO{sub 2}-CaO-Al{sub 2}O{sub 3} and SiO{sub 2}-CaO-Fe{sub 2}O{sub 3}. As a result, for the sludge-coal blend ashes series (one for each coal), the relationships between ash fusibility temperatures and the percentage of sludge ash in blend ashes fit to second-order polynomial functions. The minima of these functions, as well as some sludge-coal blend ashes, are located in the above-mentioned low fusion regions. Differing from coal ashes, in the sludge and 50 wt % blend ashes, the minerals calcium ferrite, larnite, and chloroapatite were found. 17 refs., 6 figs., 6 tabs.

M. Belen Folgueras; R. Maria Diaz; Jorge Xiberta; M. Purificacion Garcia; J. Juan Pis [University of Oviedo, Oviedo (Spain). Department of Energy and Department of Materials Science

2005-12-01

43

Mössbauer characterization of feed coal, ash and fly ash from a thermal power plant  

Science.gov (United States)

The aim of this work was apply 57Fe Transmission Mössbauer Spectroscopy at room temperature in order to study the occurrence of iron-containing mineral phases in: 1) feed coal; 2) coal ash, obtained in different stages of the ASTM D3174 standard method; and 3) fly ash, produced when coal is burned in the TERMOPAIPA IV thermal power plant localized in Boyacá, Colombia. According to obtained results, we can conclude the occurrence of pyrite and jarosite in the feed coal; Fe2+ and Fe3+ crystalline paramagnetic phases, superparamagnetic hematite and hematite in coal ash; Fe2+ and Fe3+ noncrystalline and crystalline phases, magnetite and hematite in fly ash. Precisely, for a basic understanding, this work discusses some the possible transformations that take place during coal combustion.

Reyes Caballero, F.; Martínez Ovalle, S. A.; Moreno Gutiérrez, M.

2015-02-01

44

Identification and quantification of radionuclides in coal ash. Final report  

International Nuclear Information System (INIS)

One of the important environmental issues raised recently in regard to coal ash reuse for highway construction purposes (e.g., embankment development) is that of worker, and public, exposure to radiation which might possibly be emitted by these types of residues. This research project subsequently addressed the associated issue of radiation emission by coal ash residuals generated within the State of Indiana, covering both fly ash and bottom ash materials. Samples were obtained at sixteen different coal-fired power generating facilities within Indiana and subjected to quantitative analysis of their associated gamma-ray emission levels. After identifying the responsible radionuclides, a conservative approximation was then developed for the worst-case potential occupational exposure with construction employees working on this type of high-volume, coal ash embankment. In turn, these potential emissions levels were compared to those of other traditional construction materials and other common sources

45

In vitro cytotoxic and hemolytic potential of coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

The cytotoxic and hemolytic potential of coal fly ash derived from a number of thermal power stations in India was investigated on guinea pig macrophages and mammalian erythrocytes respectively. The cytotoxic studies were carried out using graded concentrations of fly ash. Fly ash-macrophage interaction resulted in increased release of LDH into the supernatant culture medium. Acid dye uptake was enhanced only when the interaction ensued in a serum free milieu. Both the extent of enzyme release and dye uptake were significantly more in quartz exposed cultures than in those exposed to fly ash. In hemolytic assay all fly ash samples produced only a meagre hemolysis of erythrocytes, irrespective of the mammalian species from which the erythrocytes were obtained. Concentrations which produced more than 75 percent hemolysis of quartz exposed erythrocytes produced less than 10 percent hemolysis when erythrocytes were exposed to fly ash. These results reveal a weak membranolytic activity of coal fly ash. 25 refs., 1 fig., 4 tabs.

Kaw, J.L.; Khanna, A.K.; Waseem, M.

1988-01-01

46

Iron Minerals in Coal, Weathered Coal and Coal Ash - SEM and Moessbauer Results  

International Nuclear Information System (INIS)

The aim of the present investigation was to identify and quantify the iron mineral phases present in South African coal from various coal fields and in coal ash, after industrial and laboratory combustion processes, and to determine the changes that occur in these phases during weathering. Iron in coal is mainly associated with sulphur in the minerals pyrite and jarosite, whilst other iron-bearing minerals such as illite and ankerite also occur, but also occurs as a trace element in kaolinite, a major clay mineral present in coal. The amounts of these minerals vary considerably in coals from diverse origins and thus coal samples from six coal-producing areas in South Africa were studied by means of Moessbauer spectroscopy and SEM analyses. With the aid of Moessbauer spectroscopy, the iron-bearing minerals were identified in the coal, coal ash and weathered coal, whereas in the SEM analyses, apart from these minerals, the non-iron-bearing minerals were identified and found to be mainly quartz, clay minerals and carbonates. Differences in mineral composition were found between the coals from the different regions. Ash samples, obtained from the Lethabo electricity power plant, South Africa, were investigated and laboratory simulations were performed to obtain a comparable analysis of the industrial ash samples. At the high temperatures (?1400oC) of combustion in the power plant, fly ash and agglomerates are produced and the Moessbauer spectra resulted in twnd the Moessbauer spectra resulted in two poorly developed doublets, typical of glass. In the laboratory simulation, carried out at temperatures ranging from 200o to 1200oC it was clearly observed how the pyrite changed to hematite and finally was taken up in the glass in addition to the hematite that formed. The high amount of calcium present, identified by SEM analyses, resulted in the agglomeration occurring of the fly ash. The weathering products were also identified using the same techniques and it was noticed that the pyrite changed to a sulphate when the wet coal was exposed to air drying.

47

Application of zeolitised coal fly ashes to the depuration of liquid wastes  

Energy Technology Data Exchange (ETDEWEB)

In this study, the application of some zeolitised fly ashes and synthetic zeolites to the decontamination of the leachate produced in a municipal solid waste (MSW) treatment plant and to the liquid waste from a pig farm was analyzed. Thus, the reduction of organic matter (BOD and COD), ammonium and total nitrogen, phosphorus and metals contents after a zeolite treatment was evaluated. Several synthetic zeolites were tested: some commercial zeolites and other synthetic zeolites and zeolitised ashes obtained after a coal fly ash alkaline hydrothermal process. Two forms of contact between the zeolitic material and the liquid waste were tested: in a stirred tank and in a column. In addition, other variables determined were the amount of zeolite and the residence time. The results showed that zeolites, especially zeolitised fly ash, clearly produced a strong reduction in the leachate nitrogen and phosphorus content. 14 refs., 1 fig., 9 tabs.

Emilia Otal; Luis F. Vilches; Natalia Moreno; Xavier Querol; Jose Valea; Constantino Fernandez-Pereira [Universidad de Sevilla, Seville (Spain). Dpto. Ingenieria Quimica y Ambiental, E.S. Ingenieros Industriales

2005-08-01

48

Trace elements of coal, coal ashes and fly ashes by activation analysis with shor-lived nuclides  

International Nuclear Information System (INIS)

On irradiation with neutrons, some of the interesting trace elements in coal, coal ash and fly ash produce short-lived nuclides which may be determined - together with some of the matrix elements - by activation analysis. This enables the characterization of samples. To find out the distribution of elements in the gaseous or aerosol exhaust of fossil-fired power plants, the authors simulated the combustion in a quartz apparatus containing a cold trap, using the combustion temperature (780 deg C) employed for the standard ash determination. High Se values were found in the cold trap deposits of black coal from Poland. Halogens were also found in the deposits. (authors)

49

Coal ash determination by natural gamma ray measurement  

International Nuclear Information System (INIS)

Lignite from a few seams of Mae Moh Mine, Lampang normally consisted of ash content between 5-60 percent in weight. Alternate analysis of ash was shown that there are more than 40 elements including radioactive elements, i.e. Potassium-40, Uranium and Thorium series in ash. Gamma shielding for 3'' x 3'' NaI(Tl) detectors for the measurement of natural gamma ray of Lignite was developed. The results of the gamma ray activity varied with ash content in Lignite with correlation coefficient of 0.97. This radiometric instrumentation was the easy and effective method. This method can be applied for online measurements of coal ash

50

Reduction of ash deposition in pulverized coal fired boilers  

Energy Technology Data Exchange (ETDEWEB)

This study proposes reduction technology of ash deposition on the heat exchanger tube in pulverized coal fired (PCF) boilers. Thermal spraying technique is adopted to change the surface properties of tube to reduce the ash deposition. As a result, Ni alloy as a thermal spraying material played an effective role to reduce the deposition under both the ash deposition experiments and the actual coal combustion experiments. However, it is necessary to change ash types in order to evaluate that the thermal spraying technology is universally useful or not. If this technology will be applied to the commercialized PCF boilers, additionally, the effectiveness for the long-term will also be studied as well as the theoretical elucidation on the reduction of ash deposition must be discussed. In this study, therefore, four types of coal ash with different melting points were tested as samples for the ash deposition experiments. The long-term ash adhesion experiments were also carried out, using a precise tension tester at high temperature. As the theoretical approaches, the compositions of each ash particle depositing on the tube surface were analyzed by a computer-controlled scanning electron microscope (CCSEM) with electron dispersive spectroscopy (EDS) detector, thereby the interfacial reactions between the ash deposition layer and the heat exchanger tube were discussed. Those results obtained were also compared to the results obtained by the thermal equilibrium calculations.

Naruse, I.; Yoshiie, R.; Matsuura, M. [Nagoya Univ. (Japan). Dept. of Mechanical Science and Engineering; Ueki, Y. [Nagoya Univ. (Japan). Energy Science Div.; Naganuma, H. [Tohoku Electric Power Engineering and Construction, Co., Ltd. (Japan). Technical Development Center

2013-07-01

51

Composting coal ash with poultry litter for topsoil manufacture  

Energy Technology Data Exchange (ETDEWEB)

This paper describes the progress of studies using coal ash mixed with organic byproducts in a compost process as a means of converting ash to a desirable commercial product. Mixtures of fly and bottom ash, broiler chicken littler manure, sawdust and pine bark were successfully composted during the winter of 1994. The recipes and compost procedures for production of the manufactured soils are described. The physical, biological and chemical properties of the manufactured soils are being studied and the initial results presented.

Brodie, H.L.; Carr, L.E.; Biermann, E.K.; Christiana, G.A.; Udinskey, J.R. [University of Maryland, College Park, MD (United States). Dept. of Biological Resources Engineering

1996-12-31

52

Determination of ash, moisture and specific energy of coal  

International Nuclear Information System (INIS)

On-line ash gauges based on the pair production (PP) technique are in routine use on high-throughput sample by-lines in the Australian coal industry. Root mean square differences between PP gauge ash and chemical assay ash are in the range 0.21 to 0.34 wt% ash for on-line measurements on coal of up to 20 wt% ash. The PP technique is about a factor of 4 less sensitive to variations in ash composition than the alternative lower-energy ?-ray techniques. A number of techniques are being investigated by the Commonwealth Scientific and Industrial Research Organization for the on-line determination of moisture in coal. These include capacitance, microwave, neutron transmission and scattering, nuclear magnetic resonance and infra-red reflectance. One promising development is the non-contacting under-belt capacitance gauge for on-line conveyor belt determination of coal moisture. Laboratory experiments have shown that neutron techniques can be used to determine accurately the carbon and specific energy content of coal. Nuclear techniques have been used to determine coal mass flow to an industrial reverberatory furnace. (author)

53

Assessing the environmental impact of coal ash disposal  

International Nuclear Information System (INIS)

Ash produced from the combustion of brown coal in Victoria's Latrobe Valley is currently slurried into ash disposal ponds for storage. Subsequent to a review of ash production rates at the Loy Yang Power Station, a number of options for ash pond management were considered. These included excavating the aged ash from the existing pond and then depositing them downstream of the pond or into a nearby overburden dump. Prior to the re-classifying of ash, analytical testing was generally conducted on a total concentration basis and did not consider the leachable fraction of various elements from the ash. The current study of ash leaching involved the collection and testing of ash in three states, aged ash, slurry ash, and fresh ash. The analysis confirms that the aged ash, deposited within the disposal pond for 6 to 12 months, has reached the steady state point and can be considered to have a low potential for adverse impact on the beneficial use of groundwater and surface waters when excavated from the pond and dumped at other locations. It should also be noted that batch tests, where the material is shaken overnight, represents a worst case scenario of leaching. Such vigorous mixing would not normally occur in the field and consequently the leachates produced in the field can be expected to have a lower salinity for a longer period of time. (author). 6 tabs., 10 refs

54

Adsorption of Crystal Violet Dye from Aqueous Solution onto Zeolites from Coal Fly and Bottom Ashes  

Directory of Open Access Journals (Sweden)

Full Text Available The adsorption of the cationic dye Crystal Violet (CV over zeolites from coal fly ash (ZFA and bottom ash (ZBA was evaluated. The coal fly ash (CFA and the coal bottom ash (CBA used in the synthesis of the zeolites by alkaline hydrothermal treatment were collected in Jorge Lacerda coal-fired power plant located at Capivari de Baixo County, in Santa Catarina State, Brazil. The zeolitic materials were characterized predominantly as hydroxy-sodalite and X. The dye adsorption equilibrium was reached after 10 min for ZFA and ZBA. The kinetics studies indicated that the adsorption followed the pseudo-second order kinetics and that surface adsorption and intraparticle diffusion were involved in the adsorption mechanism for both the adsorbents. The equilibrium data of ZFA was found to best fit to the Langmuir model, while ZBA was best explained by the Freundlich model. The maximum adsorption capacities were 19.6 mg g-1 for the CV/ZFA and 17.6 mg g-1 for the CV/ZBA.

Tharcila Colachite Rodrigues Bertolini

2013-11-01

55

Leaching characteristics of heavy metals in fly ash from a Chinese coal-fired power plant  

Energy Technology Data Exchange (ETDEWEB)

China is the largest producer of coal ash in the world. Hydraulic ash transport systems are used in most coal-fired power plants, which lead to serious water pollution due to leaching of trace elements. The investigation on the leaching behavior of trace contaminants from coal ash is critical to environmental risk assessments. Batch leaching tests have been performed on the fly ash collected from each field of the electrostatic precipitator (ESP) of a coal-fired power plant to study the leaching characteristics of Cd, Cr, Pb and V. Leaching solutions included HCl solution of initial pH = 4 and NaOH solution of pH = 10. The liquid/solid (L/S) ratio was about 4:1 in all leaching tests. Fourteen leaching time intervals were selected, ranging from 15 min to 7 days. The results show that under studied experimental conditions, Cr has a relatively higher leachability in the acid-leaching solution, while Pb has a higher leachability in the alkaline solution. With the increase of leaching time, the leachability of Cr in each ash sample increases obviously. Within the same time interval, Cr in the ash sample from the last field of ESP has the highest leachability. The concentration of Cd in FA3 is the highest, but the leachability of Cd for FA3 is not the highest among the three ash samples. The concentration of V in FA1 is the highest; no increased trend with leaching time has been found in the experiment.

Xun Gong; Hong Yao; Dan Zhang; Yu Qiao; Lin Li; Minghou Xu [Huazhong University of Science and Technology Wuhan (China). State Key Laboratory of Coal Combustion

2010-03-15

56

Gamma isotopic analysis of the coals and ashes from coal fired power plants of Turkey  

International Nuclear Information System (INIS)

Gamma-isotopic analysis of the ashes produced by the combustion of lignite in power stations of Turkey together with the parent coal samples was performed with the aim to estimate its potential adverse impacts on human health. Gamma-isotopic analysis indicated that all samples contained 226Ra (coal samples: 89-148 Bq kg-1; ash samples: 15-26 Bq kg-1), 238U (coal samples: 2-4 ?g g-1; ash samples: 9-33 ?g g-1), 232Th (coal samples: 1-9 ?g g-1; ash samples: 8-12?g g-1), and 40K (coal samples: 26-67 Bq kg-1; ash samples: not detected). 134Cs and 137Cs have not been found in the samples. (author)

57

Gamma isotopic analysis of the coals and ashes from coal fired power plants of Turkey  

Science.gov (United States)

Gamma-isotopic analysis of the ashes produced by the combustion of lignite in power stations of Turkey together with the parent coal samples was performed with the aim to estimate its potential adverse impacts on human health. Gamma-isotopic analysis indicated that all samples contained226Ra (coal samples: 89-148 Bq kg-1; ash samples: 15-26 Bq kg-1),238U (coal samples: 2-4 ?g g-1; ash samples: 9-33 ?g g-1),232Th (coal samples: 1-9 ?g g-1; ash samples: 8-12?g g-1), and40K (coal samples: 26-67 Bq kg-1; ash samples: not detected).134Cs and137Cs have not been found in the samples.

Akyuz, T.; Varinlioglu, A.; Kose, A.

1999-01-01

58

Fly ash of mineral coal as ceramic tiles raw material.  

Science.gov (United States)

The aim of this work was to evaluate the use of mineral coal fly ash as a raw material in the production of ceramic tiles. The samples of fly ash came from Capivari de Baixo, a city situated in the Brazilian Federal State of Santa Catarina. The fly ash and the raw materials were characterized regarding their physical chemical properties, and, based on these results; batches containing fly ash and typical raw materials for ceramic tiles were prepared. The fly ash content in the batches varied between 20 and 80 wt%. Specimens were molded using a uniaxial hydraulic press and were fired. All batches containing ash up to 60 wt% present adequate properties to be classified as several kinds of products in the ISO 13006 standard () regarding its different absorption groups (pressed). The results obtained indicate that fly ash, when mixed with traditional raw materials, has the necessary requirements to be used as a raw material for production of ceramic tiles. PMID:16540298

Zimmer, A; Bergmann, C P

2007-01-01

59

Geochemistry of Indian coal and fly ash : environmental considerations  

International Nuclear Information System (INIS)

Power generation to meet the future energy demands of the growing population in India, as well as other parts of the World, will come from burning coal. The ramifications of increased coal usage are, in part, a function of the way the user perceives the resources. Informed decisions as to mining practices, which coals to use and how to dispose off waste products can only be made based on geochemical assessment of the coal and fly ash. Any evaluation of resource potential should include data on occurrence and distribution (lateral and vertical) of environmentally/economically important trace elements in the coal and preferential enrichment of these elements in fly ash relative to the coal. These data can then be used to calculate mobilization of the elements to the surface ecosystems. This work has determined the geochemistry of coals and related sediments (with emphasis on the environmentally important elements, e.g., As, Br, Cl, Co, Mn, Mo, Ni, Pb, Th, U, V, Zr, and Zn) from mine samples collected at Neyveli (2 mines), Korba (2 mines) and Talcher (1 core) which account for approximately 15% of all the coal mined in India yearly. Data from mine samples indicate significant variations in the vertical distribution of trace elements and partitioning between high and low ash samples. Analyses of feed coals and fly ash from Neyveli (2 plants), representing some 26 million metric tons of coal per year, indicate enrichment of as much as 10 times in some trace elements in fly as 10 times in some trace elements in fly ash relative to the coal. (author). 14 refs., 9 figs

60

Environmentally friendly use of non-coal ashes in Sweden.  

Science.gov (United States)

The Swedish Thermal Engineering Research Institute (Värmeforsk) initiated an applied research program "Environmentally friendly use of non-coal ashes", in 2002. The program aims at increasing knowledge on the by-products of energy production and their application. The goal of formulating technical and environmental guidelines and assessments is a major point of the program, which is supported by about forty authorities and private organisations. The programme has been divided into four areas: recycling of ashes to forests, geotechnical applications, use in landfilling, and environmental aspects and chemistry. Among all results obtained, the following progress is shown: *Evidence for the positive effects of spreading ashes on forest growth. *A proposal for environmental guidelines on the utilisation of ashes in construction. *A handbook for using non-coal fly ashes in unpaved roads. *Technical and environmental assessments of MSWI bottom ashes in road construction. *Development of the use of ashes with municipal wastewater sludge as a cover for landfills and mine tailings. *Use of ashes from bio-fuels in concrete and replacement of cement in stoop mining. *A method to classify those by-products from combustion that have mirror entries in the EWC as a hazardous or non-hazardous compound. The Ash Programme has also made it possible to increase knowledge on ashes as valuable materials, on quality assurance and on markets for recovered materials. PMID:17521898

Ribbing, C

2007-01-01

61

Coal Ash Corrosion Resistant Materials Testing  

Energy Technology Data Exchange (ETDEWEB)

In April 1999, three identical superheater test sections were installed into the Niles Unit No.1 for the purpose of testing and ranking the coal ash corrosion resistance of candidate superheater alloys. The Niles boiler burns high sulfur coal (3% to 3.5%) that has a moderate alkali content (0.2% sodium equivalents), thus the constituents necessary for coal ash corrosion are present in the ash. The test sections were controlled to operate with an average surface metal temperature from approximately 1060 F to 1210 F which was within the temperature range over which coal ash corrosion occurs. Thus, this combination of aggressive environment and high temperature was appropriate for testing the performance of candidate corrosion-resistant tube materials. Analyses of the deposit and scale confirmed that aggressive alkali sulfate constituents were present at the metal surface and active in tube metal wastage. The test sections were constructed so that the response of twelve different candidate tube and/or coating materials could be studied. The plan was to remove and evaluate one of the three test sections at time intervals of 1 year, 3 years, and 5 years. This would permit an assessment of performance of the candidate materials as a function of time. Test Section A was removed in November 2001 after about 24 months of service at the desired steam temperature set point, with about 15.5 months of exposure at full temperature. A progress report, issued in October 2002, was written to document the performance of the candidate alloys in that test section. The evaluation described the condition of each tube sample after exposure. It involved a determination of the rate of wall thickness loss for these samples. In cases where there was more than one sample of a candidate material in the test section, an assessment was made of the performance of the alloy as a function of temperature. Test Sections B and C were examined during the November 2001 outage, and it was decided that, due to excessive wastage, certain tube samples needed to be removed and replaced in order to ensure that Test Sections B and C would have a chance of remaining in the boiler for their intended exposure period. These suspect tube samples were replaced and the two remaining test sections were put back into service. The tube samples that were removed from Test Sections B and C were set aside for later analysis at the end of the planned exposure period. Test Sections B and C were again examined approximately six months later. At that time, measured wall thickness losses raised concerns about additional tube samples. These suspect samples were also removed, set aside for later analysis, and replaced. The test sections then went back into service until the end of the second exposure period, which was concluded in May 2003 when, due to evidence of excessive wastage, the valves were opened increasing cooling steam flow and thereby effectively stopping corrosion. In August 2003, Test Sections B and C were removed for closer examination. Section C had experienced about 42 months of service at the desired team temperature set point with 28.5 months at temperature at full temperature. Additional suspect samples were removed from Test Section B, then, it was re-installed into the boiler (at the location originally occupied by Section C), where it remained in service until the end of the program. Due to this removal history, the samples from Test Section B had a total service duration that varied from a minimum of 15.5 months (for samples that performed poorly) to 37 months for samples the survived for the full intended service exposure for Section B. The figure below shows a schematic of Test Section B and indicates the length of service exposure for different locations. This report provides the results of the evaluation of Test Section B, including the samples that remained in the Test Section for the full exposure period as well as those that were removed early. This report also is intended to compare and summarize the results for all three test sections. The analysis of T

D. K. McDonald; P. L. Daniel; D. J. DeVault

2007-12-31

62

Characterization of Coal Ash Emissivity in High Temperature Atmospheres  

Science.gov (United States)

This paper presents a method for determining coal ash emissivity in high temperature atmospheres. We applied a tube-dropping mechanism to suppress reflection from the sample, and tried other new approaches for measurements at high temperatures. One approach was a shielding time reduction using tube motorization, which reduces measurement errors to a negligible level. Another approach was determining emissivity by fitting a calculation curve to transient experimental data. In these calculations, adjustable parameters were emissivity and thermal conductivity. An ash sample was heated in an electric furnace in the range from 500 to 1300°C and the radiation intensity from the sample was measured with a digital pyrometer. Each measurement was carried out within 0.3 seconds, including the time required for shielding the sample (0.1 seconds). Once the tube had been dropped into the furnace, radiation intensities from the sample began decreasing. Emissivity characteristics were compared between Powder River Basin (PRB) coal ash and bituminous coal ash. It was found that coal-ash emissivity depends on coal types and changes significantly as a function of ash surface temperature.

Shimogori, Miki; Yoshizako, Hidehisa; Shimogori, Yoshio; Richardson, Mark

63

How toxic is coal ash? A laboratory toxicity case study.  

Science.gov (United States)

Under a consent agreement among the Environmental Protection Agency (EPA) and proponents both for and against stricter regulation, EPA is to issue a new coal ash disposal rule by the end of 2014. Laboratory toxicity investigations often yield conservative estimates of toxicity because many standard test species are more sensitive than resident species, thus could provide information useful to the rule-making. However, few laboratory studies of coal ash toxicity are available; most studies reported in the literature are based solely on field investigations. This brief communication describes a broad range of toxicity studies conducted for the Tennessee Valley Authority (TVA) Kingston ash spill, results of which help provide additional perspective on the toxicity of coal ash. PMID:25348557

Sherrard, Rick M; Carriker, Neil E; Greeley, Mark S

2015-01-01

64

Ash formation under pressurized pulverized coal combustion conditions  

Science.gov (United States)

Coal combustion is a source of inorganic particulate matter (ash), which can deposit in boilers and also be emitted into the atmosphere becoming part of ambient fine particulate matter (PM 2.5). In order to decrease coal combustion emissions per unit of power produced, higher efficiency systems have been proposed, including systems operating at elevated pressures. These new operating conditions will affect pollutant formation mechanisms, particularly those associated with the conversion of mineral matter to ash. Ash particle formation mechanisms are particularly sensitive to changes in pressure as they are related to the structure of coal char particles at early stages of combustion. To assess the importance of pressure on ash particle formation, pyrolyzed chars and ash particles from pressurized pulverized combustion of two bituminous and one subbituminous U.S. coals at operating pressures up to 30 atm were studied. Pressure changes the distribution of char particle types, changing the spatial distribution of the minerals during the combustion process and therefore affecting particle formation mechanisms. Chars were examined by Scanning Electron Microscopy (SEM) and classified into two different types (cenospheric and solid) depending on porosity and wall thickness. A correlation for estimating the amount of these cenospheric char particles was then proposed for bituminous coals based on the operating conditions and coal maceral analysis. The ash particle size distribution of the coals combusted at different operating pressures was measured using Computer Controlled Scanning Electron Microscopy (CCSEM). The results of the char characterization and ash particle size distribution measurements were then incorporated into an ash particle formation algorithm that was proposed and implemented. The model predicts ash particle size and composition distributions at elevated pressures under conditions of complete char burnout. Ash predictions were calculated by first developing char structure distribution functions based on coal characteristics. To obtain an ash particle size distribution, carbon is then allowed to react away while following coalescence, fragmentation and other transformation processes as combustion proceeds. Particle size distributions calculated with this model showed qualitative agreement with the trends identified in the experimental portion of this research.

Davila Latorre, Aura Cecilia

65

Rheological properties of alkaline activated fly ash used in jet grouting applications  

OpenAIRE

The application of alkaline activated fly ash to soil stabilisation has been recently studied, and although the structural behaviour was adequate, some concerns were raised regarding its apparent viscosity, which proved to be an important issue in jet grouting applications. Therefore, this paper deals with the experimental study of rheology of alkaline activated fly ash-based grouts, namely with: setting time of the freshly mixed grout; fluidity; capillary absorption; shrinkage and expansion ...

Cristelo, Nuno; Soares, Edgar; Rosa, Ivo; Miranda, Tiago F. S.; Oliveira, Daniel V.; Silva, Rui Andre? Martins Da; Chaves, Ana Margarida Vaz Alves

2013-01-01

66

Effects of colemanite waste, coal bottom ash, and fly ash on the properties of cement  

Energy Technology Data Exchange (ETDEWEB)

The physical and chemical properties of colemanite ore waste from concentrator, coal bottom ash, fly ash, cement+ash mixtures, cement+colemanite ore waste, and their effects on the mechanical properties of concrete were investigated. These materials with different proportion were substituted with Portland cement. Physical properties such as setting time, volume expansion, and compressive strength were determined and compared to reference mixture and Turkish standards (TS). The results showed that cement replacement materials had clear effects on the mechanical properties. The use of fly ash and bottom ash even at the concentration of 25% showed either comparable or better result compared to reference mixture. Although replacement of Portland cement by 9 wt.% of colemanite ore waste causes reduction in the compressive strength, the values obtained are within the limit of TS. As a result, colemanite ore waste, fly ash, and bottom ash may be used as cementitious materials.

Kula, I.; Olgun, A.; Erdogan, Y.; Sevinc, V. [Celal Bayar University, Manisa (Turkey)

2001-03-01

67

Ash fusion temperatures and the transformations of coal ash particles to slag  

Energy Technology Data Exchange (ETDEWEB)

A mechanistic study is detailed in which coal ash is heated with its shrinkage measured continuously up to a temperature of 1600{degree}C. The temperature corresponding to the rapid rate of shrinkage correspond to the formation of eutectics identified on phase diagrams. Samples were therefore heated to these temperatures, cooled rapidly and examined using a scanning electron microscope (SEM) to identify the associated chemical and physical changes. The progressive changes in the range of chemical composition (from SEM), the extent of undissolved ash particles and porosity were then quantified and related to homogenisation, viscosity and ash fusion mechanisms. Alternate ash fusion temperatures based on different levels of shrinkage have also been suggested to characterise the ash deposition tendency of the coals. 13 refs., 9 figs.

Gupta, S.K.; Wall, T.F.; Creelman, R.A.; Gupta, R.P. [University of Newcastle, Newcastle, NSW (Australia). CRC for Black Coal Utilisation

1998-07-01

68

COAL-FIRED UTILITY BOILERS: SOLVING ASH DEPOSITION PROBLEMS; TOPICAL  

International Nuclear Information System (INIS)

The accumulation of slagging and fouling ash deposits in utility boilers has been a source of aggravation for coal-fired boiler operators for over a century. Many new developments in analytical, modeling, and combustion testing methods in the past 20 years have made it possible to identify root causes of ash deposition. A concise and comprehensive guidelines document has been assembled for solving ash deposition as related to coal-fired utility boilers. While this report accurately captures the current state of knowledge in ash deposition, note that substantial research and development is under way to more completely understand and mitigate slagging and fouling. Thus, while comprehensive, this document carries the title ''interim,'' with the idea that future work will provide additional insight. Primary target audiences include utility operators and engineers who face plant inefficiencies and significant operational and maintenance costs that are associated with ash deposition problems. Pulverized and cyclone-fired coal boilers are addressed specifically, although many of the diagnostics and solutions apply to other boiler types. Logic diagrams, ash deposit types, and boiler symptoms of ash deposition are used to aid the user in identifying an ash deposition problem, diagnosing and verifying root causes, determining remedial measures to alleviate or eliminate the problem, and then monitoring the situation to verify that the problem has been solved. In addition to a stoblem has been solved. In addition to a step-by-step method for identifying and remediating ash deposition problems, this guideline document (Appendix A) provides descriptions of analytical techniques for diagnostic testing and gives extensive fundamental and practical literature references and addresses of organizations that can provide help in alleviating ash deposition problems

69

Assessment of the impact of radionuclides in coal ash  

International Nuclear Information System (INIS)

An assessment of the potential environmental and health impacts of radionuclides in the coal fuel cycle is being conducted at Mound. This paper describes studies evaluating the potential for migration of radionuclides from ash disposal sites. Studies at a power plant burning western-US coal dealt with an assessment of potential radiation doses from coal ash ponds and leachate discharges of radionuclides from the ponds. Emanation of 222Rn from the ash is relatively low. The emanation of 222Rn from the ash pond (226Ra at 4.5pCi.g-1) is predicted to be about six times less than from soil (226Ra at 1pCi.g-1). Ash with 226Ra at 25pCi.g-1 would approximate emanation of 222Rn from soil. At 1000m from the centre of the ash pond area, 222Rn from the ash pond is predicted to be 1000 to 6000 times less than background (0.1 to 0.5pCi.ltr-1). Pathways exist for transport of radionuclides leached from ash into the aquifer beneath the holding ponds, but concentrations of radionuclides in water leaving the ponds are lower than concentrations in groundwater which is upgradient of the ponds. Leachability of the ash is quite low, on the order of 0.002% in one month, and flow of ash-sluicing water (3% of the volume of the ponds each day) has actually diluted normal background concentrations of radionuclides in the aquifer between the ponds and the adjacent river. (authen the ponds and the adjacent river. (author)

70

A seasonal assessment of the impact of coal fly ash disposal on the River Yamuna, Delhi. I. Chemistry  

International Nuclear Information System (INIS)

The impact of fly ash on the chemistry of the River Yamuna was studied. By-products from a 200 MW capacity Indraprasha thermal power station on the west bank of the River Yamuna, Delhi are largely from coal combustion (fly ash) and are disposed of as a slurry in off-site ash ponds. Many elements associated with fly ash are soluble and become available to the biota. A two-year survey was made of the seasonal variations in limnochemical features in the non-impacted and the impacted segments of the river receiving fly ash effluent and the ash treatment ponds. Conductivity, TDS, DO, hardness, sulphate and nitrate increased significantly in the receiving waters over background values. The reverse was noticed for free CO2, alkalinity and phosphate. Changes in some other parameters were insignificant. Fly ash effluent from the ash ponds significantly increased the concentration of some elements, viz., Al, Sb, Bi, Cd, Co, Cr, Li, Mn, Mo, K, Si and Zn in river water. Generally, the highest concentration of most parameters were recorded in the ash ponds. This investigation was helpful in assessing the effect of wet ash disposal on the river limnology and understanding the solubility of various elements in the ash ponds. 50 refs., 6 figs., 1 tab

71

Community views about the health and exposure of children living near a coal ash storage site.  

Science.gov (United States)

Coal ash, a waste product generated from burning coal, is composed of small particles comprised of highly toxic elements. Coal ash particles contain heavy metals such as arsenic, lead, and mercury, as well as polyaromatic hydrocarbons and radioactive elements. Most coal ash is stored in landfills and ponds, often located in close proximity to low income communities. Currently, there are no federal regulations governing the storage and transport of coal ash; however the Environmental Protection Agency proposed a coal ash rule in 2010, which could designate coal ash as a hazardous waste. This is the first article to assess community impact from coal ash storage, by exploring parents' perceptions of their children's health and its relationship to chronic exposure to coal ash. This was a community-based study involving four neighborhoods adjacent to a large coal ash storage facility. Focus groups were conducted with community members and the transcripts were analyzed to identify themes regarding children's health, children's exposure to coal ash, and behaviors done to protect children from exposure. The majority of parents (85 %) reported that their children suffered from health conditions; specifically respiratory and emotional and behavioral disorders. Parents highlighted ways in which their children were exposed to coal ash, although many felt they were constantly exposed just by living in the area. Parents felt strongly that exposure to coal ash from the landfill is affecting the health and well-being of their children. Some parents attempted protective behaviors, but most parents felt helpless in reducing children's exposure. PMID:25204532

Zierold, Kristina M; Sears, Clara G

2015-04-01

72

Study of the correlation between the coal calorific value and coal ash content using X-ray fluorescence analysis  

Science.gov (United States)

In this paper we have studied the possibility of determining the chemical elements in coal samples using X-ray fluorescence analysis and have found a relationship between the coal calorific value and its ash content with the coal moisture accounting. The amount of coal ash can be determined by the content of the basic chemical elements, such as Si, Sr, Fe, and Ca. It was concluded that the calorific value of coal can be estimated from the ash content in coal without the calorimetric measurements. These correlation coefficients were calculated for coal from several coal mines in Mongolia. The results are in good agreement with the results of chemical analysis.

Bolortuya, D.; Zuzaan, P.; Gustova, M. V.; Maslov, O. D.

2013-12-01

73

SIROASH gauges for on-line determination of ash in coal  

International Nuclear Information System (INIS)

Two new coal ash gauges have been developed for direct use on coal carrying conveyors and for use on sample by-lines. One depends on the absorption of low energy gamma-rays, and the second on the production of gamma-ray pairs. The accuracy for both gauges is better than 0.5% by weight ash for low-ash coals, and, for the Pair Production gauge, better than 1% for high-ash coals

74

Is coal ash and slag any useful or unloaded wastes?  

International Nuclear Information System (INIS)

It is well known that all types of coal, like most materials found in nature, contain trace quantities of the naturally occurring primordial radionuclides (uranium and thorium families and potassium-40). Therefore, the combustion of coal results in partitioning of radionuclides included in the non-combustible mineral matter, between the bottom ash and fly ash, and in the release into the environment of large amounts of coal ash. Emissions from thermal power stations in gaseous and particulate form contain radioisotopes arising from the uranium and thorium series as well as from 40K. They are discharged into the environment causing changes in the natural radiation background and radiation exposures to the population. The continued releases of these materials to environment may result in a buildup in the air, water and soil of the radionuclides, particularly radium-226. There will be an increase of the basic radiation rate in the neighborhood area of these plants and consequently relatively higher exposure of the local population to radiation. Coal burning is, therefore, one of the sources of technologically enhanced exposure to humans from natural radionuclides (1,2,3,4,5,6). Coal based thermal power plants constitute about 35% of quantum of energy supply in Romania. In view of the importance of coal for energy supply in Romania, we were interested in knowing possible uses of the resulting wastes and minimize the following harmful consequences of coal burning

75

Toxicity of and metals in coal combustion ash leachate  

International Nuclear Information System (INIS)

Land disposal of coal combustion ash can have a potential impact on the ecosystem due to the leaching of metals with increasing acidity of precipitation. The effect of pH on the concentration of metals leached from coal combustion ash was studied and the toxicity of the leachate measured. Bottom coal combustion ash was leached with hydrochloric acid (HCl) or acetic acid (CH3COOH) at pH 4,5,6 or 7. The toxicity of the aqueous leachates and concentrations of the metals (arsenic, cadmium, chromium, copper, iron, lead, nickel, silver and zinc) therein were measured using Microtox (Vibrio fischeri-EC50%) and atomic absorption spectrophotometry, respectively. Toxicity and metal concentrations of the leachates were highest when ash was leached with HCl at pH 4. Toxicity and metal concentrations of ash leached with CH3COOH were significantly lower compared with ash leached with HCl. A high correlation was observed between the toxicity and the metal concentrations in both the acid leachates

76

Alkaline leaching of coal by the mechanochemical treatment  

Directory of Open Access Journals (Sweden)

Full Text Available The possibility of application of a new process GACL (Grinding and Aqueous Caustic Leaching for the reduction of mineral components in the brown coal Nováky was tested. The simultaneous grinding and chemical leaching enable us to extract 41 % total sulphur, 95 % arsenic and to reduce the ash content to 43 %. The process proceeds at the atmospheric pressure, temperature 90oC and in diluted NaOH solutions (5 %.

Turèániová ¼udmila

1998-09-01

77

Determination of the ash content of coal using annihilation radiation  

International Nuclear Information System (INIS)

The ash content of coal can be determined by a simple technique based on the simultaneous measurement of 0.511 MeV annihilation radiation and Compton scattered radiation which result from irradiation of a coal sample with ?-rays of energy > 1.022 MeV. The technique has been tested by many laboratory measurements on 57 bulk coal samples, each weighing 100-200 kg, from three different areas of Australia. These measurements were performed using a 60Co source and 7.6 cm x 7.6 cm NaI(T1) detector in a backscatter geometry. The r.m.s. deviations between chemical laboratory ash and ash measured on the backscatter gauge were in the range of 0.46 to 1.37 wt.%. Compared with X-ray methods of ash analysis which depend on a single measurement proportional to the mass absorption coefficient, the annihilation radiation method has the advantages of less sensitivity to high Z elements such as Fe and Ca, less sensitivity to moisture variations and potentially greater depth penetration because of the higher energies used. The main potential applications of the technique are for the continuous analysis of coal on conveyor belts, in chutes or in hoppers. Such analysis is required mainly for the control of coal washeries and blending operations. (orig.)

78

Properties of Concrete using Tanjung Bin Power Plant Coal Bottom Ash and Fly Ash  

Directory of Open Access Journals (Sweden)

Full Text Available Coal combustion by-products (CCPs have been around since man understood that burning coal generates electricity, and its utilization in concrete production for nearly a century. The concept of sustainable development only reawaken our consciousness to the huge amount of CCPs around us and the need for proper reutilization than the current method of disposal which has  severe consequences both to man and the environment. This paper presents the result of utilization of waste from thermal power plants to improve some engineering properties of concrete. Coal bottom ash (CBA and fly ash were utilized in partial replacement for fine aggregates and cement respectively. The results of compressive strength at 7, 28, 56 & 90 days curing are presented because of the pozzolanic reaction. Other properties investigated include physical properties, fresh concrete properties and density. The results showed that for a grade 35 concrete with a combination of CBA and fly ash can produce 28 day strength above 30 MPa.

Abdulhameed Umar Abubakar

2012-11-01

79

Fly ash and concrete: a study determines whether biomass, or coal co-firing fly ash, can be used in concrete  

Energy Technology Data Exchange (ETDEWEB)

Current US national standards for using fly ash in concrete (ASTM C618) state that fly ash must come from coal combustion, thus precluding biomass-coal co-firing fly ash. The co-fired ash comes from a large and increasing fraction of US power plants due to rapid increases in co-firing opportunity fuels with coal. The fly ashes include coal fly ash, wood fly ash from pure wood combustion, biomass and coal co-fired fly ash SW1 and SW2. Also wood fly ash is blended with Class C or Class F to produce Wood C and Wood E. Concrete samples were prepared with fly ash replacing cement by 25%. All fly ash mixes except wood have a lower water demand than the pure cement mix. Fly ashes, either from coal or non coal combustion, increase the required air entraining agent (AEA) to meet the design specification of the mixes. If AEA is added arbitrarily without considering the amount or existence of fly ash results could lead to air content in concrete that is either too low or too high. Biomass fly ash does not impact concrete setting behaviour disproportionately. Switch grass-coal co-fired fly ash and blended wood fly ash generally lie within the range of pure coal fly ash strength. The 56 day flexure strength of all the fly ash mixes is comparable to that of the pure cement mix. The flexure strength from the coal-biomass co-fired fly ash does not differ much from pure coal fly ash. All fly ash concrete mixes exhibit lower chloride permeability than the pure cement mixes. In conclusion biomass coal co-fired fly ash perform similarly to coal fly ash in fresh and hardened concrete. As a result, there is no reason to exclude biomass-coal co-fired fly ash in concrete.

Wang, Shuangzhen; Baxter, Larry

2006-08-01

80

Experiments for the analysis of ash and sulphur of low-ash coal with radioisotope Fe-55  

International Nuclear Information System (INIS)

For the purpose of the automation of coal preparation process, the experiment on the rapid analysis of ash and sulphur in low-ash coal was carried out at the Miike Coal Preparation Plant using radioisotope Fe-55 of 80ci. The Mnx ray from this radioisotope was irradiated to the surface of coal powder sample, and the back-scattered and the fluorescent X-ray was detected by a Xe-sealed proportional counter. The energy analysis was made with filters and pulse-height analyzers, and finally, the analytical values of ash and sulphur were calculated with the established regression equations. The results obtained are as follows. It took approximately 25 min from the automatic sampling of clean coal to the display of the calculated results. The accuracy of the regression equations for the clean coal of Miike was 0.2% for ash and 0.1% for sulphur. This method is also applicable to other low-ash coal than Miike, but in the case of extremely low-sulphur coal, the regression equation for ash should be established separately. The optimum X-ray analysis can be made when coal powder samples pass through a 0.25 mm mesh by 85 to 95%, and the moisture content is less than 1%. As the Ca content in ash is higher, the O/C atomic ratio of coal is larger, and the analytical value of ash is higher. (Kako, I.)

81

Study of the correlation between the coal calorific value and coal ash content using X-ray fluorescence analysis  

International Nuclear Information System (INIS)

In this paper we have studied the possibility of determining the chemical elements in coal samples using X-ray fluorescence analysis and have found a relationship between the coal calorific value and its ash content with the coal moisture accounting. The amount of coal ash can be determined by the content of the basic chemical elements, such as Si, Sr, Fe, and Ca. It was concluded that the calorific value of coal can be estimated from the ash content in coal without the calorimetric measurements. These correlation coefficients were calculated for several coal mines in Mongolia. The results are in good agreement with the results of chemical analysis

82

An Evaluation on the Physical and Chemical Composition of Coal Combustion Ash and Its Co-Placement with Coal-Mine Waste Rock  

Directory of Open Access Journals (Sweden)

Full Text Available In the last few decades, the utilization of coal to generate electricity was rapidly increasing. Consequently, the production of coal combustion ash (CCA as a by-product of coal utilization as primary energy sources was increased. The physical and geochemical characteristics of CCA were site-specific which determined by both inherent coal-source quality and combustion condition. This study was intended to characterize the physical, chemical and mineralogical properties of a coal-combustion ash (CCA from a site specific power plant and evaluate the leachate characteristic of some scenario on the co-placement of CCA with coal-mine waste rock. The physical properties such as specific gravity, dry density, porosity and particle size distribution were determined. Chemically, the CCA sample is enriched mainly in silica, aluminum, iron, and magnesium along with a little amount of calcium and sodium which includes in the class C fly ash category. Moreover, it is found that the mineral phases identified in the sample were quartz, mullite, aragonite, magnetite, hematite, and spinel. Co-placement experiment with mudstone waste rock shows that the CCA, though it has limited contribution to the decreasing permeability, has important contributed to increase the quality of leachate through releasing higher alkalinity. Moreover, addition of CCA did not affect to the increase of the trace metal element in the leachate. Hence, utilization of CCA by co-placement with coal mine waste rock in the dumping area is visible to be implemented.

Budi Sulistianto

2012-07-01

83

Ash fusion temperatures and the transformations of coal ash particles to slag  

Energy Technology Data Exchange (ETDEWEB)

A mechanistic study is detailed in which coal ash is heated with the shrinkage and electrical resistance measured continuously up to a temperature of 1600{degrees}C. The temperatures corresponding to rapid rates of shrinkage are shown to correspond to the formation of eutectics identified on phase diagrams. Samples where therefore heated to these temperatures, cooled rapidly and examined with an SEM to identify the associated chemical and physical changes. The progressive changes in the range of chemical analysis (from SEM), the extent of undissolved ash particles and porosity are then quantified and related to the shrinkage events and standard ash fusion temperatures.

Wall, T.F.; Creelman, R.A.; Gupta, R.; Gupta, S. [Univ. of Newcastle (Australia)

1996-10-01

84

Ash fusion temperatures and the transformations of coal ash particles to slag  

Energy Technology Data Exchange (ETDEWEB)

A mechanistic study is detailed in which coal ash is heated with its shrinkage measured continuously up to a temperature of 1600{degrees}C. The temperatures corresponding to the rapid rate of shrinkage are shown to correspond to the formation of eutectics identified on phase diagrams. Samples were therefore heated to these temperatures, cooled rapidly and examined with an SEM to identify the associated chemical and physical changes. The progressive changes in the range of chemical analysis (from SEM), the extent of undissolved ash particles and porosity were then quantified and related to homogenization, viscosity and ash fusion mechanisms.

Gupta, S.; Wall, T.F.; Creelman, R.A.; Gupta, R. [Univ. of Newcastle, Callaghan (Australia)

1996-12-31

85

Leaching behaviour of elements from coal combustion fly ash : an overview  

OpenAIRE

Coal-based power generation produces over 750 Mt of coal ash per year globally, but under 50% of world production is utilised. Large amounts of fly ash are either stored temporarily in stockpiles, disposed of in ash landfills or lagooned. Coal ash is viewed as a major potential source of release of many environmentally sensitive elements to the environment. This paper encompasses over 90 publications on coal fly ash and demonstrates that a large number of elements are tightly bound to fly ash...

Izquierdo, Maria; Querol, Xavier

2012-01-01

86

Mode of occurrence of arsenic in feed coal and its derivative fly ash, Black Warrior Basin, Alabama  

Science.gov (United States)

An arsenic-rich (As = 55 ppm) bituminous feed coal from the Black Warrior Basin, Alabama and its derivative fly ash (As = 230 ppm) were selected for detailed investigation of arsenic residence and chemical forms. Analytical techniques included microbeam analysis, selective extraction, and As K-edge X-ray absorption fine-structure (XAFS) spectroscopy. Most As in the coal is contained in a generation of As-bearing pyrite (FeS2) that formed in response to epigenetic introduction of hydrothermal fluids. XAFS results indicate that approximately 50% of the As in the coal sample occurs as the oxidized As(V) species, possibly the result of incipient oxidation of coal and pyrite prior to our analysis. Combustion of pyrite and host coal produced fly ash in which 95% of As is present as As(V). Selective extraction of the fly ash with a carbonate buffer solution (pH = 10) removed 49% of the As. A different extraction with an HCl-NH2OH mixture, which targets amorphous and poorly crystalline iron oxides, dissolved 79% of the As. XAFS spectroscopy of this highly acidic (pH = 3.0) fly ash indicated that As is associated with some combination of iron oxide, oxyhydroxide, or sulfate. In contrast, a highly alkaline (pH = 12.7) fly ash from Turkey shows most As associated with a phase similar to calcium orthoarsenate (Ca3(AsO4)2). The combined XAFS results indicate that fly ash acidity, which is determined by coal composition and combustion conditions, may serve to predict arsenic speciation in fly ash.

Zielinski, R.A.; Foster, A.L.; Meeker, G.P.; Brownfield, I.K.

2007-01-01

87

Integrated production/use of ultra low-ash coal, premium liquids and clean char  

Energy Technology Data Exchange (ETDEWEB)

This integrated, multi-product approach for utilizing Illinois coal starts with the production of ultra low-ash coal and then converts it to high-vale, coal-derived, products. The ultra low-ash coal is produced by solubilizing coal in a phenolic solvent under ChemCoal{trademark} process conditions, separating the coal solution from insoluble ash, and then precipitating the clean coal by dilution of the solvent with methanol. Two major products, liquids and low-ash char, are then produced by mild gasification of the low-ash coal. The low ash-char is further upgraded to activated char, and/or an oxidized activated char which has catalytic properties. Characterization of products at each stage is part of this project.

Kruse, C.W.

1991-01-01

88

Prospects of technological instrumental control of ash content in coal  

Energy Technology Data Exchange (ETDEWEB)

Considers estimation of ash content in run-of-mine coal by calculating it from measurements of seam thickness and coal-cutting with stone, and by measuring nuclear radiation passed through the monitored material. A new method developed at DonUGI is described that utilizes measurements of the material's natural gamma radiation. The method was laboratory tested on over 700 samples taken from 55 mines in the Donbass. The level of gamma radiation depending on ash content was investigated using the overall content of radioactive elements and count rate and using also separately the content of uranium, radium and thorium. Radiation spectra obtained from coal and rock were of identical nature and differed only in the intensity of lines corresponding to the individual naturally radioactive elements. A high correlation coefficient (0.74) between the overall content of radioactive elements and the ash content was found in all seams in the Donbass. Experimental prototypes of ash content analyzers based on that principle and developed at DonGI have an accuracy of {plus minus} 2%. Schemes of ash content control for mines with conveyor and rail transport are presented. Production of the analyzers on order is planned starting in 1990.

Klempner, K.S.; Sapunov, G.P.; Shamshin, V.N. (DonUGI (USSR))

1989-10-01

89

Coal ash usage in environmental restoration at the Hanford Site  

Energy Technology Data Exchange (ETDEWEB)

This paper discusses the use of coal ash from Hanford Nuclear Reservation steam plants as codisposal waste rock, landfill, or tank stabilization material; usage as a fuel source for energy recovery, as pipe or foundation backfill, or as an ornamental brick additive; and as aquarium rock, jewelry, or oyster bed stabilization material. Reducing the amount of waste produced is also discussed.

Scanlon, P.L.; Sonnichsen, J.C.; Phillips, S.J. [Westinghouse Hanford Co., Richland, WA (United States)

1995-09-01

90

FILTRATION MODEL FOR COAL FLY ASH WITH GLASS FABRICS  

Science.gov (United States)

The report describes a new mathematical model for predicting woven glass filter performance with coal fly ash aerosols from utility boilers. Its data base included: an extensive bench- and pilot-scale laboratory investigation of several dust/fabric combinations; field data from t...

91

Use of coal-ash for casuarina forest biomass production  

Energy Technology Data Exchange (ETDEWEB)

Fly-ash from a coal-fired power plant was used as an amendment for an acid flatwoods soil in north central Florida. Seedlings of Casuarina cunninghamiana grew to 3.9 m height in three growing seasons with 127 Mg/ha of dry coal-ash applied to the soil. This was 2.5 times the growth of trees on a control plot. Biomass production on the ash-amended soil was 9.8 Mg/ha and on the control was 1.4 Mg/ha. Growth on smaller plots receiving half or twice the ash amendment rate suggested proportional growth. The major environmental effect of the unweathered ash on soil and runoff water was a significant decrease in acidity because of the liming effect. The surface soil pH increased from 4.2 to 6.6 and runoff water pH increased from 4.3 to 6.1. The change in pH was due to the addition of cations and caused a higher extractability of P, As Zn, and Mn that originally were fixed in the soil. This change in mineral extractability was reflected in runoff water for P and Ca during the first year and for K, Ca, and Mg in the following years. Nitrogen in runoff was not affected by the ash treatment but Zn tended to increase in runoff water over time. 16 references.

Riekerk, H.; Kohrnak, L.V.

1984-01-01

92

Analysis of radioactivity in coal, cinders, fly ash and discharges from the stack  

International Nuclear Information System (INIS)

Gamma measurements of coal samples originating from several supplying countries proved that the South African coal has about double U-238 and Ra-226 concentration and about treble Th-232 concentration compared to coal from the other countries. Gamma measurements of coal, cinders and fly ash samples from five coal-fueled plants indicate somewhat higher concentrations of Th-232 in cinders and U-238 and Th-232 in fly ashes than those described in literature. The ratio Po-210/Pb-210 was about 2 for fly ash particulates <35?. A positive correlation between ash percentage and radioactivity of coal might be assumed. (EG)

93

Production of ceramics from coal fly ash  

OpenAIRE

Dense ceramics are produced from fly ash from REK Bitola, Republic of Macedonia. Four types of fly ash from electro filters and one from the collected zone with particles < 0.063 mm were the subject of this research. Consolidation was achieved by pressing (P= 133 MPa) and sintering (950, 1000, 1050 and 11000C and heating rates of 3 and 100/min). Densification was realized by liquid phase sintering and solid state reaction where diopside [Ca(Mg,Al)(Si,Al)2O6] was formed. Ceramics with...

Angjusheva Biljana; Fidancevska Emilija; Jovanov Vojo

2012-01-01

94

Radioactive analysis of coal ash sampled from the east China area and simulative experiment for using coal ash in farmland  

International Nuclear Information System (INIS)

Sampling from the electric power plants of Zhejiang, Fujian, Shandong, Jiangxi, Anhui and Jiangsu, 16 coal ash samples were measured respectively by HPGE ?-spectrometer analyzer. The results showed that the main composition of radioactive nuclide are 238U, 232Th, their daughter nuclides and 40K. The activity ratio of 238U, 232Th and 40K ranges from 75 Bq/kg to 284 Bq/kg, from 60 Bq/kg to 164 Bq/kg and from 120 Bq/kg to 738 Bq/kg, respectively. The simulated experiment on coal ash used to farmland showed that the activity ratio of natural radioisotope 226Ra and 228Ra in the simulated soil were 1.88 and 1.39 times higher than those in ordinary soil respectively when amount of the coal ash used was up to 525 t/hm2. The activity ratio of two nuclides in crop (rice, maize and wheat seed) grown in the farmland applied with coal ash and those of the ordinary farmland have no evident difference. The effect of edible security is not evident

95

Laboratory determination of the ash content of some Australian coals using radioisotope techniques  

International Nuclear Information System (INIS)

Two radioisotope techniques suitable for the rapid laboratory determination of the ash content of coal have been tested on unwashed coal samples from four Australian coal seams. In one technique, measurements of backscattered 238Pu L X-rays and iron K X-rays from finely ground coal samples have been combined to determine ash content in unwashed coals to +- 0.5 weight per cent ash for three seams and +- 0.9 weight per cent ash for the fourth. The second technique, which involves measurements of the transmission by the coal of narrow beams of 241Am 60 keV and 133Ba 356 keV ?-rays, requires less sample preparation. The ash was determined to within the range of 0.8 to 2.6 weight per cent for the four seams (unwashed coal). For washed coals, errors are expected to be <+-0.5 weight per cent ash

96

Correction of pair production gauge ash determinations for changes in coal ash composition  

International Nuclear Information System (INIS)

The ash content of coal can be determined by a technique based on pair production (PP). The PP technique has been previously proved in the laboratory and in the field, and five commercial PP gauges are in routine use at coal washeries in Australia. However for some applications on coals of highly variable ash composition, there is a need for improved accuracy. Calculations and experiments have been made to investigate two methods of improving PP gauge accuracy for coals with highly variable ash composition. The first combines the PP gauge measurement with measurements of the low-energy part of the PP gauge spectrum and the second is done in conjuction with separate low and high energy ?-ray transmission measurements. Calculations show that these methods can correct the PP gauge assay exactly when the concentration of a single high-Z element in the ash varies. When more than one element varies, the error reduction is less and depends on the elements and their variations. Experiments with a group of samples from Blackwater, Queensland showed that gauge accuracy improved by about 20% relative using the first method. Use of the second method on two groups of samples from Blackwater and South Africa produced about 15% improvement. There was no reduction in error when either method was used on a third group of samples from the Hunter Valley New South Wales. (author)

97

The use of coal fly ash for soil stabilization  

Energy Technology Data Exchange (ETDEWEB)

The objective of this work was to examine the potential use of Wyoming subbituminous coal fly ash materials for cementation of soil materials. Specimens made from Laramie River (LR) fly ash had higher unconfined compression strength and more brittleness than the Specimens made with Dave Johnston (DJ) fly ash. However, soil/DJ fly ash mixtures that were cured for 28 days had relatively good strengths without the brittleness that the LR specimens developed. These characteristics of the DJ fly ash may be important attributes for road stabilization applications. The detailed mineralogical evaluation provides some insight into which minerals may enhance development of strength in these materials. In general, selective dissolution of the soil/fly ash mixtures shows that many of the potentially toxic elements (e.g., B, Cr, Fe, Mn, Ni, Pb) are associated with the sulfide phase (HNO{sub 3} extractable) and with the residual material. In this study, the dynamics of elemental release from the element pools did not result in toxic conditions. The formation of colloidal material capable of mobilizing potentially toxic elements was not found in the soil/fly ash mixtures. Apparently, the high pH of the materials enhanced immobilization of the high molecular weight material.

Brown, T.H.; Brown, M.A.; Sorini, S.S.; Huntington, G.

1991-12-01

98

Composition, diagenetic transformation and alkalinity potential of oil shale ash sediments  

Energy Technology Data Exchange (ETDEWEB)

Oil shale is a primary fuel in the Estonian energy sector. After combustion 45-48% of the oil shale is left over as ash, producing about 5-7 Mt of ash, which is deposited on ash plateaus annually almost without any reuse. This study focuses on oil shale ash plateau sediment mineralogy, its hydration and diagenetic transformations, a study that has not been addressed. Oil shale ash wastes are considered as the biggest pollution sources in Estonia and thus determining the composition and properties of oil shale ash sediment are important to assess its environmental implications and also its possible reusability. A study of fresh ash and drillcore samples from ash plateau sediment was conducted by X-ray diffractometry and scanning electron microscopy. The oil shale is highly calcareous, and the ash that remains after combustion is derived from the decomposition of carbonate minerals. It is rich in lime and anhydrite that are unstable phases under hydrous conditions. These processes and the diagenetic alteration of other phases determine the composition of the plateau sediment. Dominant phases in the ash are hydration and associated transformation products: calcite, ettringite, portlandite and hydrocalumite. The prevailing mineral phases (portlandite, ettringite) cause highly alkaline leachates, pH 12-13. Neutralization of these leachates under natural conditions, by rainwater leaching/neutralization and slow transformation (e.g. carbonation) of the aforementioned unstable phases into more stable forms, takes, at best, hundreds or even hundreds of thousands of years.

Motlep, Riho, E-mail: riho.motlep@ut.ee [Department of Geology, University of Tartu, Ravila 14A, 50411 Tartu (Estonia); Sild, Terje, E-mail: terje.sild@maaamet.ee [Estonian Land Board, Mustamaee tee 51, 10621 Tallinn (Estonia); Puura, Erik, E-mail: erik.puura@ut.ee [Institute of Technology, University of Tartu, Nooruse 1, 50411 Tartu (Estonia); Kirsimaee, Kalle, E-mail: kalle.kirsimae@ut.ee [Department of Geology, University of Tartu, Ravila 14A, 50411 Tartu (Estonia)

2010-12-15

99

Composition, diagenetic transformation and alkalinity potential of oil shale ash sediments.  

Science.gov (United States)

Oil shale is a primary fuel in the Estonian energy sector. After combustion 45-48% of the oil shale is left over as ash, producing about 5-7 Mt of ash, which is deposited on ash plateaus annually almost without any reuse. This study focuses on oil shale ash plateau sediment mineralogy, its hydration and diagenetic transformations, a study that has not been addressed. Oil shale ash wastes are considered as the biggest pollution sources in Estonia and thus determining the composition and properties of oil shale ash sediment are important to assess its environmental implications and also its possible reusability. A study of fresh ash and drillcore samples from ash plateau sediment was conducted by X-ray diffractometry and scanning electron microscopy. The oil shale is highly calcareous, and the ash that remains after combustion is derived from the decomposition of carbonate minerals. It is rich in lime and anhydrite that are unstable phases under hydrous conditions. These processes and the diagenetic alteration of other phases determine the composition of the plateau sediment. Dominant phases in the ash are hydration and associated transformation products: calcite, ettringite, portlandite and hydrocalumite. The prevailing mineral phases (portlandite, ettringite) cause highly alkaline leachates, pH 12-13. Neutralization of these leachates under natural conditions, by rainwater leaching/neutralization and slow transformation (e.g. carbonation) of the aforementioned unstable phases into more stable forms, takes, at best, hundreds or even hundreds of thousands of years. PMID:20855159

Mõtlep, Riho; Sild, Terje; Puura, Erik; Kirsimäe, Kalle

2010-12-15

100

Composition, diagenetic transformation and alkalinity potential of oil shale ash sediments  

International Nuclear Information System (INIS)

Oil shale is a primary fuel in the Estonian energy sector. After combustion 45-48% of the oil shale is left over as ash, producing about 5-7 Mt of ash, which is deposited on ash plateaus annually almost without any reuse. This study focuses on oil shale ash plateau sediment mineralogy, its hydration and diagenetic transformations, a study that has not been addressed. Oil shale ash wastes are considered as the biggest pollution sources in Estonia and thus determining the composition and properties of oil shale ash sediment are important to assess its environmental implications and also its possible reusability. A study of fresh ash and drillcore samples from ash plateau sediment was conducted by X-ray diffractometry and scanning electron microscopy. The oil shale is highly calcareous, and the ash that remains after combustion is derived from the decomposition of carbonate minerals. It is rich in lime and anhydrite that are unstable phases under hydrous conditions. These processes and the diagenetic alteration of other phases determine the composition of the plateau sediment. Dominant phases in the ash are hydration and associated transformation products: calcite, ettringite, portlandite and hydrocalumite. The prevailing mineral phases (portlandite, ettringite) cause highly alkaline leachates, pH 12-13. Neutralization of these leachates under natural conditions, by rainwater leaching/neutralization and slow transformation (e.g. carbonation) of the aforementioned unstablcarbonation) of the aforementioned unstable phases into more stable forms, takes, at best, hundreds or even hundreds of thousands of years.

101

Environmental impact of coal ash on tributary streams and nearshore water or Lake Erie. Final report  

Energy Technology Data Exchange (ETDEWEB)

The environmental impact of coal ash disposal at a landfill site in north-central Chautauqua County, New York was studied from June 1975 through July 1977. Water samples taken from wells, ponds, and streams at 67 sites were analyzed for specific conductance, pH, alkalinity, arsenic, calcium, cadmium, chloride, chromium, copper, iron, magnesium, manganese, potassium, selenium, sodium, sulfate and zinc. Evidence suggests that ponds at the landfill were high in Ca, Fe, Mg, Mn, and SO/sub 4/ compared to control pands. A stream adjacent to the site contained greater Mn (207 ug/1) and SO/sub 4/ (229 ppm) than control streams. Shallow alkaline test wells in the landfill had elevated As, Ca, and Se. Acid-neutral test wells had elevated As, Ca, Cr, Mg and Mn. Household wells in the vicinity of the landfill showed no evident contamination from the landfill. Average iron concentrations in the biota were tripled, and manganese concentrations doubled in biota affected by the coal ash dump. However, any effects of the disposal area on the distribution of the biota could not be separated from effects of varying environment factors such as water movements, substrate composition and food availability. No harmful effects could be demonstrated on the biota in the creek which flowed past the disposal area.

Wood, K.G.

1978-08-01

102

Combustion characteristics of high ash South African coal reserves  

Energy Technology Data Exchange (ETDEWEB)

An investigation was undertaken to determine the properties and combustion reactivities of typical high-ash coals (30% to 50% by weight) originating from many mining sites in South Africa, in order to generate information for the development of fluidised bed combustors. The coals were bituminous and of medium rank (reflectance 0.58%-0.78%) with compositions (organic/inorganic) within the following ranges (by volume), 7% - 66% pure inertinite, 2%-31% pure vitrinite, 11%-42% bi- and tri-macerites, 9%-33% carbominerites and 7%-34% minertite. A thermogravimetric analyser was used for the determination of the reactivities and different reaction models were evaluated. Raw coals were combusted in a reactive gaseous medium. The experimental conditions at which the combustion experiments were carried out were chosen to be similar to that used in fluidised bed combustion. Isothermal combustion experiments were conducted with 1 mm coal particles at atmospheric pressure (87.5 kPa) and at reaction temperature between 750{sup o}C and 900{sup o}C with a gas mixture consisting of 21 mole % oxygen in nitrogen. The initial devolatilisation period which was very rapid depended on the coal type and temperature and was distinctly different to the combustion period. Results from the combustion of the resulting chars only were examined and the dependence of the reactivities of the coals on the reaction temperature and properties of the parent coal were evaluated. Carbon conversion results at the higher temperatures were found to be very close to one another, which is characteristic of overall reactions controlled by diffusion mechanisms. Correlations of the reactivity with ash and inertinite contents were also obtained. A shrinking core model consisting of a combination of film diffusion, diffusion through the ash layer, and surface chemical reaction agreed very well with experimental results. 23 refs., 11 figs., 6 tabs.

R.C. Everson; P.D. Kalibantonga; H.W.J.P. Neomagus; N.J. Wagner [North-West University, Potchefstroom (South Africa). School of Chemical and Minerals Engineering

2009-07-01

103

Production of ceramics from coal fly ash  

Directory of Open Access Journals (Sweden)

Full Text Available Dense ceramics are produced from fly ash from REK Bitola, Republic of Macedonia. Four types of fly ash from electro filters and one from the collected zone with particles < 0.063 mm were the subject of this research. Consolidation was achieved by pressing (P= 133 MPa and sintering (950, 1000, 1050 and 11000C and heating rates of 3 and 100/min. Densification was realized by liquid phase sintering and solid state reaction where diopside [Ca(Mg,Al(Si,Al2O6] was formed. Ceramics with optimal properties (porosity 2.96±0.5%, bending strength - 47.01±2 MPa, compressive strength - 170 ±5 MPa was produced at 1100ºC using the heating rate of 10ºC/min.

Angjusheva Biljana

2012-01-01

104

Usage of Ash from Coal incineration in Wuhai, China  

OpenAIRE

This master thesis has been carried out at Industrial Ecology at Royal Institute ofTechnology, KTH, in cooperation with Swedish Environmental Research Institute, IVL.This thesis discussed the usage of the ash from coal incineration in Wuhai, Inner Mongolia,China by studying and analyzing the fly ash from the case plant, the North Power Company.In the first part, there are some background information about the study area, like Wuhaicity and the case plant, the North Power Company. The study fo...

Sun, Shiyu

2007-01-01

105

Mineralogy of Indian coal fly ash  

International Nuclear Information System (INIS)

Samples of ash obtained from a number of Indian thermal plants, from various points of collection have been chemically analysed and their stoichiometric mineral compositions have been calculated. Mineralogical constituents have also been determined by X-ray analysis as well as observed under optical microscope. The results have been compared. Formation of various mineral phases have been discussed and their environmental implication in solid waste disposal has been pointed out. (author). 22 refs

106

Alkaline hydrothermal conversion of fly ash filtrates into zeolites 2: utilization in wastewater treatment.  

Science.gov (United States)

Filtrates were collected using a codisposal reaction wherein fly ash was reacted with acid mine drainage. These codisposal filtrates were then analyzed by X-ray Fluorescence spectrometry for quantitative determination of the SiO2 and Al2O3 content. Alkaline hydrothermal zeolite synthesis was then applied to the filtrates to convert the fly ash material into zeolites. The zeolites formed under the experimental conditions were faujasite, sodalite, and zeolite A. The use of the fly ash-derived zeolites and a commercial zeolite was explored in wastewater decontamination experiments as it was applied to acid mine drainage in different dosages. The concentrations of Ni, Zn, Cd, As, and Pb metal ions in the treated wastewater were investigated. The results of the treatment of the acid mine drainage with the prepared fly ash zeolites showed that the concentrations of Ni, Zn, Cd, and Hg were decreased as the zeolite dosages of the fly ash zeolite (FAZ1) increased. PMID:15991728

Somerset, Vernon; Petrik, Leslie; Iwuoha, Emmanuel

2005-01-01

107

Hierarchical zeolites from class F coal fly ash  

Science.gov (United States)

Fly ash, a coal combustion byproduct is classified as types class C and class F. Class C fly ash is traditionally recycled for concrete applications and Class F fly ash often disposed in landfills. Class F poses an environmental hazard due to disposal and leaching of heavy metals into ground water and is important to be recycled in order to mitigate the environmental challenges. A major recycling option is to reuse the fly ash as a low-cost raw material for the production of crystalline zeolites, which serve as catalysts, detergents and adsorbents in the chemical industry. Most of the prior literature of fly ash conversion to zeolites does not focus on creating high zeolite surface area zeolites specifically with hierarchical pore structure, which are very important properties in developing a heterogeneous catalyst for catalysis applications. This research work aids in the development of an economical process for the synthesis of high surface area hierarchical zeolites from class F coal fly ash. In this work, synthesis of zeolites from fly ash using classic hydrothermal treatment approach and fusion pretreatment approach were examined. The fusion pretreatment method led to higher extent of dissolution of silica from quartz and mullite phases, which in turn led to higher surface area and pore size of the zeolite. A qualitative kinetic model developed here attributes the difference in silica content to Si/Al ratio of the beginning fraction of fly ash. At near ambient crystallization temperatures and longer crystallization times, the zeolite formed is a hierarchical faujasite with high surface area of at least 360 m2/g. This work enables the large scale recycling of class F coal fly ash to produce zeolites and mitigate environmental concerns. Design of experiments was used to predict surface area and pore sizes of zeolites - thus obviating the need for intense experimentation. The hierarchical zeolite catalyst supports tested for CO2 conversion, yielded hydrocarbons up to C9, a performance attesting the hierarchal pore structure. The preliminary techno-economic feasibility assessment demonstrates a net energy saving of 75% and cost saving of 63% compared to the commercial zeolite manufacturing process.

Chitta, Pallavi

108

Structural and hydrological alterations of soil due to addition of coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

Purpose: We tested the potential of using coal fly ash for improving the physical and hydrological characteristics of coarse and medium-textured agricultural soils. Materials and methods: Acidic (FWA) and alkaline (FNSW) fly ashes were used to amend a range of representative agricultural soils. In the first experiment, fly ash was applied to the top 10 cm of 1-m long intact cores of a sandy loam soil at rates of 0, 12, 36 or 108 Mg/ha and sown with canola; after harvest, bulk density (BD), aggregate stability and mean weight diameter (MWD) were measured on the soil. In the second experiment, we assessed water retention at field capacity (-300 kPa) and permanent wilting point (-1,500 kPa) for sandy and loamy soils amended with FNSW at 0.0-16% (w/w). The third experiment used rainfall simulation to assess erodibility of sandy and loamy soils mixed with FNSW at rates of 0, 5 or 20 Mg/ha. Results and discussion: In the first experiment, fly ash had no significant effect on MWD of the soil. The BD in the 0-10 cm layer (topsoil) was increased with addition of FWA, while FNSW applied at 108 Mg/ha reduced BD, relative to the control treatment. This was because FNSW had lower particle and bulk densities than FWA and the test soils. Ash addition increased macro-aggregation, significantly so in the 10-20 cm layer (subsurface layer), by reducing the percentages of micro-aggregates and silt + clay particles. Thus, macro-aggregation was positively correlated (p < 0.01) with MWD, but both were inversely correlated (p < 0.01) with micro-aggregates. In the second experiment, addition of fly ash enhanced plant water availability by increasing water retention at field capacity by threefold in the sandy soil and 1.5-fold in the loamy sand, but water retention at permanent wilting point was not affected. In Experiment 3, the addition of ash at 20 Mg/ha, but not at 5 Mg/ha, increased turbidity of runoff water from the amended soil due to the dispersal of fine particles by the impact of the simulated raindrops. Conclusions: Moderate rates of fly ash (< 12 Mg/ha or {<=} 2% w/w) addition can improve aggregation and plant water availability in light to medium-textured soils. Soil applications thus provide a significant end-use for fly ash and can be a part of strategies for minimising environmental footprints from coal-fired power generation. Future studies are needed to further optimise application practices for long-term sustainability. (orig.)

Yunusa, Isa A.M. [New England Univ., Armidale, NSW (Australia). School of Environmental and Rural Sciences; Manoharan, V.; Skilbeck, C. Greg; Eamus, Derek [University of Technology, Sydney, Broadway, NSW (Australia). Dept. of Environmental Science; Odeh, Inakwu O.A. [Sydney Univ., NSW (Australia). Faculty of Agriculture, Food and Natural Resources; Shrestha, Surendra [Western Sydney Univ., Penrith South DC, NSW (Australia). School of Engineering, College of Health and Science

2011-04-15

109

Effect of coal ash disposal upon an unconfined alluvial system  

International Nuclear Information System (INIS)

Fly and bottom ash from coal combustion has been disposed in four ash ponds in an alluvial valley. Three of the ash ponds are receiving ash and one was filled and closed. Twenty eight monitoring wells ranging in depth from 10 feet to 65 feet have been installed at the site to study groundwater flow and chemistry. Hydraulic heads are influenced by the stage of the Kentucky River, and the flow direction is vertical below the ash ponds and predominantly horizontal a short distance from the pond all the way to the river. Three different groundwater flow zones were observed and have unique water chemistry. The deep zone (near bedrock) has a low Eh ( 100) and lower concentrations of Fe and ammonia nitrogen, median sulfate concentration (114 mg/l), and arsenic is below detection limits. The shallow groundwater zone is through the closed out ash point and has higher concentrations of nearly all cations and anions, including sulfate (888 mg/l) and arsenic (exists as arsenite) at concentration of 0.9 mg/l, low Eh (< -100), and high pH. When shallow flow enters the alluvium, the sulfate are attenuated by sulfate reduction and this results in high bicarbonate values. Saturation indicesigh bicarbonate values. Saturation indices (SI) as calculated by the geochemical model, MINTEQA2, indicate that deep and intermediate groundwater are unsaturated and shallow groundwater is at or near equilibrium with respect to calcite, dolomite, and gypsum

110

Mineralogy and chemistry of conventional and fluidised bed coal ashes  

Directory of Open Access Journals (Sweden)

Full Text Available Coal combustion residues represent very abundant inorganic waste materials. The change from conventional combustion of powdered North Bohemian brown coal to its combustion in fluidised bed boilers in several Czech power and heating plants calls for detailed mineralogical and geochemical characterisation of the combustion residues. The main differences between fly ashes from both combustion systems result from different burning temperatures and differing systems of desulphurisation (coeval with combustion / post-combustion. Both these factors influence the chemical and phase compositions as well as the speciation of trace elements. The study further shows that the validity of the surface enrichment model (Linton et al. 1975 can be limited.

Sulovský P

2002-03-01

111

Substoichiometric isotope dilution analysis of tin in coal fly ash  

International Nuclear Information System (INIS)

An accurate and precise analytical method for traces of tin by substoichiometric isotope dilution has been investigated. The present method consists of the extraction of tin(IV) as iodide into benzene, the complex formation of tin(IV) with the substoichiometric amount of salicylideneamino-2-thiophenol in the benzene phase. The reproducibility of the substoichiometric separation is satisfactorily good, and the determination of tin in microgram order can be expected. The high selectivity of this method has been ascertained by adding 17 foreign metals and 11 radioactive tracers to the tin(IV) solution. The present method has been applied to the determination of tin in environmental materials, NBS Coal Fly Ash (SRM 1633) and fly ash from coal-fired power plant in Japan

112

JV Task 6 - Coal Ash Resources Research Consortium Research  

Energy Technology Data Exchange (ETDEWEB)

The Coal Ash Resources Research Consortium{reg_sign} (CARRC{reg_sign}, pronounced 'cars') focuses on performing fundamental and applied scientific and engineering research emphasizing the environmentally safe, economical use of coal combustion by-products (CCBs). CARRC member organizations, which include utilities and marketers, are key to developing industry-driven research in the area of CCB utilization and ensuring its successful application. The U.S. Department of Energy is a partner in CARRC through the EERC Jointly Sponsored Research Program (JSRP), which provides matching funds for industrial member contributions and facilitates an increased level of effort in CARRC. CARRC tasks were designed to provide information on CCB performance, including environmental performance, engineering performance, favorable economics, and improved life cycle of products and projects. CARRC technical research tasks are developed based on member input and prioritization. CARRC special projects are developed with members and nonmembers to provide similar information and to support activities, including the assembly and interpretation of data, support for standards development and technology transfer, and facilitating product development and testing. CARRC activities from 1998 to 2007 included a range of research tasks, with primary work performed in laboratory tasks developed to answer specific questions or evaluate important fundamental properties of CCBs. CARRC topical reports were prepared on several completed tasks. Specific CARRC 1998B2007 accomplishments included: (1) Development of several ASTM International Standard Guides for CCB utilization applications. (2) Organization and presentation of training courses for CCB professionals and teachers. (3) Development of online resources including the Coal Ash Resource Center, Ash from Biomass in Coal (ABC) of cocombustion ash characteristics, and the Buyer's Guide to Coal-Ash Containing Products. In addition, development of expanded information on the environmental performance of CCBs in utilization settings included the following: (1) Development of information on physical properties and engineering performance for concrete, soil-ash blends, and other products. (2) Training of students through participation in CARRC research projects. (3) Participation in a variety of local, national, and international technical meetings, symposia, and conferences by presenting and publishing CCB-related papers.

Debra Pflughoeft-Hassett; Tera Buckley; Bruce Dockter; Kurt Eylands; David Hassett; Loreal Heebink; Erick Zacher

2008-04-01

113

Reuse of ash coal in the formulation of mortars  

International Nuclear Information System (INIS)

This paper aims to study the ash incorporation from the combustion of coal in fluidized bed boilers, in production of mortar, replacing part of cement. Specimens were prepared using Portland cement to the specifications CPII-E-32 of normal characteristics and classification of sand below 100 mesh. Blends in the 4:1 ratio, that is, 4 parts of aggregate to 1 part of cement, with insertion of ashes in the proportions 0, 10, 20, 30, 40 and 50%. The mortar was developed in mixing and casting was made in a mold of 5 cm x 10 cm. The behavior of compressive strength was evaluated after 28 days; the strength decreases with increasing percentage of ash. Additional analysis was carried out by X-ray diffraction, and it was found that the substitution of this waste can be successfully used in mortars with blends of up to 30%. (author)

114

Adsorption of coal ash to low concentration uranium in solution  

International Nuclear Information System (INIS)

The adsorptive characteristics of pulverized-coal ash to uranium in the waste water is studied in detail, which includes the adsorptive effect to low concentration uranium,the adsorptive capacity and the effect factors. The experiment shows that the adsorptive effect is significant with the concentration of uranium declining rapidly within 76 hours. The adsorptive efficiency of uranium is about 82%. Total iron, ferric iron in the solution decrease at the same time with the increase of pH value. (authors)

115

Direct Quantitative Analysis of Arsenic in Coal Fly Ash  

OpenAIRE

A rapid, simple method based on graphite furnace atomic absorption spectrometry is described for the direct determination of arsenic in coal fly ash. Solid samples were directly introduced into the atomizer without preliminary treatment. The direct analysis method was not always free of spectral matrix interference, but the stabilization of arsenic by adding palladium nitrate (chemical modifier) and the optimization of the parameters in the furnace program (temperature, rate of temperature in...

Sri Hartuti; Shinji Kambara; Akihiro Takeyama; Kazuhiro Kumabe; Hiroshi Moritomi

2012-01-01

116

Thermal expansion of slag and fly ash from coal gasification  

OpenAIRE

Integrated gasification in combined cycle (IGCC) is an electrical power generation system, which is characterized to be a clean coal technology different than conventional process in combustible treatment. IGCC process gives rise to inorganic solid wastes in the form of vitreous slag and fly ashes with singular thermal properties. The gasification of the fuel takes place at high temperature and pressure in reducing atmosphere. Under those conditions, gases such as H2, N2 or CO, which are the ...

Aineto, Mo?nica; Acosta, Anselmo; Rinco?n Lo?pez, Jesu?s Mari?a; Romero, Maximina

2006-01-01

117

Forecasting ash content in coal seams on the basis of geologic survey results  

Energy Technology Data Exchange (ETDEWEB)

Evaluates a method of forecasting ash content in coal seams in Donbass mines, based on proved correlations between seam thickness, thickness increase, type of coal, rank, and types of rocks in seam floor and roof. The correlations have been calculated for the Donbass on the basis of copious statistical material. The results of analyses are shown in two tables and two diagrams. C/SUP/3/SUB/2 coal seams are characterized by the lowest ash content (about 11%). C/SUP/5/SUB/2 coal seams have an ash content of 13.8%, and C/SUP/7/SUB/2 seams have an ash content of 13.1%. Ash content of petrographically homogeneous carboniferous coals increases with increasing seam thickness. It is caused by complications in geologic structure and presence of rock partings in coal seams. Ash content of partings which consist of argillites amounts to 77%. Argillites form about 69.5% of rock partings. About 23% of partings are made up of coaly argillites with average ash content of 53.3%, 5.5% of aleurites (81.2% ash content), and 2% of sandstones (ash content 80.7%). Zh, K, and OS types of coal are characterized by the lowest ash content. Fluctuations of ash content in coal seams are most intensive in the Donetsk-Makeevsk region. (In Russian)

Ochkur, N.P.

1981-07-01

118

Geotechnical properties of fly ash and lime-fly ash stabilized coal mine refuse for highway construction  

Energy Technology Data Exchange (ETDEWEB)

The present study was designed to determine the geotechnical properties of coal refuse from one of several mines in southern Illinois and to assess the possibility of using it, along with fly ash produced by burning local coal, to construct highway embankments and base courses. Tests have been conducted to determine the gradation, standard Proctor compaction characteristics, triaxial shear strength, California Bearing Ratio, and hydraulic conductivity. Degradation of refuse particles as a result of the compaction process also has been investigated. The laboratory studies were conducted both on untreated specimens and on specimens stabilized with varying amounts of fly ash and lime-fly ash mixtures. According to ASTM C628, this may be classified as a type F fly ash. Fly ash used to treat the coal refuse samples was obtained from a nearby power plant that uses coal from southern Illinois mines. The details of the tests conducted and the results obtained are discussed herein.

Puri, V.; Yen, S.; Das, B.; Devkota, B. [Southern Illinois Univ.. Carbondale, IL (United States)

1994-12-31

119

Dry bottom ash technology improves coal fired boiler operations  

Energy Technology Data Exchange (ETDEWEB)

In the Spanish coal fired power plant of Los Barrios, owned and operated by Endesa Generaion, an innovative dry technology has been retrofitted reducing strongly the operating and maintenance costs for the bottom ash and pyrites handling, and in the same time providing a reduction of the environmental impact of the plant. In particular, the use of water in bottom ash handling and the production of waste water has been eliminated completely, and the boiler's heat losses have been reduced, leading to a saving of coal consumption and a reduction of gaseous emissions including CO{sub 2}. Additional benefits of the project include a higher dependability of the system, preventing forced boiler outages, and a better saleability of the bottom ash. In this paper, an analysis of the performance of the power plant's previous wet bottom ash and pyrites handling is provided, leading to the reasons for replacing it by the dry system. Initial operating results of the new dry system are also presented to evaluate the improvements achieved. 5 refs., 3 figs., 2 tabs.

Carrieri, R.; Giraldez, J.A.H. [Magaldi Power S.p.A., Salerno (Italy)

2004-07-01

120

Groundwater impact studies at three Ontario Hydro coal ash landfills  

International Nuclear Information System (INIS)

Ontario Hydro has produced on the order of 21 million Mg of coal fly ash over the past 40 years, of which, 80% has gone to various landfill sites in the province of Ontario. Hydrogeologic investigations have been performed in the vicinity of three Ontario Hydro coal ash landfill sites to assess the environmental impact of fly ash landfilling on the local groundwater regime. Two of the waste management facilities are associated with thermal generating stations (Lambton TGS and Nanticoke TGS) and are founded on relatively impermeable clay deposits. The third site, Birchwood Park, is a former sand and gravel pit for which the landfill design did not incorporate the use of a liner material. The rates of groundwater flow through the overburden materials a the three sites vary from less than 1 cm/a at the Lambton TGS site, to between 3.45 cm/a and 115 cm/a at contaminant transport at these sites also varies from being controlled by molecular diffusion to advection. This paper discusses the migration rates of contaminants from fly ash leachate at each of the three sites with implications to landfill containment and design

121

Ash fusion temperatures and their association with the transformations of coal ash particles to slag  

Energy Technology Data Exchange (ETDEWEB)

Ash deposition on furnace walls in PF (pulverized fuel) furnaces is called slagging when it occurs in the high temperature areas of furnaces directly exposed to flame radiation and fouling in other regions such as tubes in the convection section of the boiler. There are well documented shortcomings of certain approaches relating to their uncertainties as predictive tools for plant performance such as poor repeatability and re-producibility of ash fusion measurements. The nature of physical and chemical changes occurring during melting of coal ash has been investigated in the current study to provide an alternative procedure to the ash fusion test. Shrinkage measurements are frequently used in metallurgy and ceramic science to study the physical properties of materials at high temperatures. The output of this experiment provides three to four `peaks` (maximum rate of shrinkage with temperature) of different intensity and at different temperatures which are related to melting characteristics of the sample. It was concluded that shrinkage extents exceeding 50 percent indicated that the effect of the ash particle size is of secondary importance compared to ash chemistry in determining shrinkage levels, with fine particles giving rapid shrinkage events 10 degrees C lower in temperature. (author). 7 figs., refs.

Gupta, S.K.; Wall, T.F.; Gupta, R.P. [Cooperative Research Centre for Black Coal Utilisation, Newcastle, NSW (Australia); Creelman, R.A. [Creelman (R.A.) and Associates, Sydney, NSW (Australia)

1997-04-01

122

Water Retention Characteristics of Porous Ceramics Produced from Waste Diatomite and Coal Fly Ash  

Directory of Open Access Journals (Sweden)

Full Text Available This study examines potential waste diatomite and coal fly ash reuse to prepare water absorption and retain porous ceramics. The operating conditions are constant pressure (5 MPa, sintering temperature (1000-1270°C, sintering time (2 h, waste diatomite containing coal fly ash at different proportions (0-20%, respectively. The porous ceramic samples containing coal fly ash show low thermal conductivity properties (0.278-0.349 W/mK, probably owing to the more pores than those in the concrete (1.458 W/mK. Water release (t1/2 value by the porous ceramic samples is decelerated by porous ceramic samples containing coal fly ash, due to the synergy effect of high water absorption by the coal fly ash and better than in the foamed glass material (4 h. Porous ceramic samples containing coal fly ash is highly promising for use in water absorption and retention applications.

Kae-Long Lin

2013-07-01

123

Analytical methods relating to mineral matter in coal and ash from coal combustion  

Energy Technology Data Exchange (ETDEWEB)

The paper begins by describing the minerals that occur in coal, as well as trace elements. The testing methods that are then described include those that are in the main the standard tools for the examination and assessment of minerals in coal and ash. The techniques discussed include optical and beam techniques, X-ray methods and a variety of other useful methods. 12 refs.

Creelman, R.A. [Ultra-Systems Technology Pty. Ltd., Indooroopilly, Qld. (Australia)

2002-07-01

124

Assessment of tolerant sunfish populations (Lepomis sp.) inhabiting selenium-laden coal ash effluents - 2. Tissue biochemistry evaluation  

Energy Technology Data Exchange (ETDEWEB)

Sunfish were collected from a fly ash pond-receiving stream and an Ohio River reference site to assess biochemical responses to coal ash effluent exposure. Selenium levels in sunfish from the receiving stream were higher than toxic thresholds associated with adverse population effects and reproductive impairment. Tissue biochemistry was found to be indicative of metal exposure and effect, but varied widely. Liver glycogen was positively correlated with increased liver metal levels, indicating no adverse effect upon stored carbohydrate levels. Lipid levels decreased with increasing metals, indicating possible nutritional stress. Protein levels increased with increasing metal levels, possibly due to the synthesis of proteins to sequester the metals. ATPase, dUTPase, and alkaline phosphatase activity generally decreased with exposure to ash pond metals, but remained within normal physiological ranges. Fish condition factors and liver somatic indices were correlated with liver lipid levels, dUTPase activity, and gill ATPase and alkaline phosphatase activity. Exposure to coal ash effluents produced biochemical markers of exposure that were associated with fish condition indicators; however, the indices themselves were not significantly affected by effluent exposure.

Lohner, T.W.; Reash, R.J.; Williams, M. [American Electric Power Co., Columbus, OH (United States). Environmental Services Dept.

2001-07-01

125

Determining ash content in power coal by spectrometry of scattered gamma radiation  

International Nuclear Information System (INIS)

Spectrometers are described used for determining ash content in coal of a grain size up to 10 mm. The results obtained showed that spectrometers of scattered gamma radiation could be employed. The amount of ash in coal, this up to 45% of the ash content could be directly assessed from the pulse rate pertaining to the peak of the measured spectrum or from the measured spectra ratios. The accuracy of ash content de--termination was +-2%. (J.B.)

126

Estimation of natural radioactivity in the ash generated from coal fired thermal power plants  

International Nuclear Information System (INIS)

In the present study, coal, bottom ash and fly ash samples collected from three coal-fired power plants in India were measured for natural-U, 226Ra, 232Th and 40K by an HPGe ?-ray spectrometer. The results were compared with the available data from earlier studies in other countries. To assess the radiological hazard of fly ash and bottom ash used as building materials, the radium equivalent activity (Raeq) and external hazard index (Hex) are used in the study

127

Evaluation and Treatment of Coal Fly Ash for Adsorption Application  

Directory of Open Access Journals (Sweden)

Full Text Available Many researchers had investigated fly ash as an adsorbent for the uptake of organic compounds from petrochemical waste effluents. The availability, inexpensive and its adsorption characteristic had made it an alternative media for the removal of organic compounds from aqueous solution. The physical property of South African Coal Fly Ash (SACFA was investigated to determine its adsorption capability and how it can be improved. Chemical treatment using 1M HCl solution in the ratio of (1 g fly ash to (2 ml of acid was used and compared with untreated heat-treated samples. The chemically treated fly ash has a higher specific surface area of 5.4116 m2/g than the heat-treated fly ash with 2.9969 m2/g. More attention had to be given to the utilization of SACFA for the treatment of wastewaters containing organic compounds through the application of Liquid phase adsorption process that was considered as an inexpensive and environmentally friendly technology.

Samson Oluwaseyi BADA

128

Radiometric online ash monitor for coal industry using fuzzy logic  

Energy Technology Data Exchange (ETDEWEB)

Online nuclear meters have been in use in the coal industry for many years. They have been utilized for coal quality monitoring, in the control systems for coal blending, or for separating coals in the heavy media separation process. Their operation is based on the scattering or the absorption of incident gamma radiation, and the derived density or ash value is the result of a time-averaged measurement. In this paper, dynamic models of ash monitors have been presented and discussed. The analysis of monitors with constant time of measurement shows that it is possible to determine the optimal time for which the dynamic error is the smallest. The analysis also shows that the monitors in which the time of measurement is variable and adapts to changes of the input signal give better results. A fuzzy logic decision table has been applied to control the time of measurement according to variations of the input signal. The simulation of the system operation has been performed with the use of the Matlab (Simulink) program package.

Cierpisz, S.; Heyduk, A. [Silesian Technical University, Gliwice (Poland). Dept. of Electrical Engineering & Production Control Mining

2001-10-01

129

The experimental gamma-gamma probe for bulk analysis of ash content in coal  

International Nuclear Information System (INIS)

This paper presents an experimental model of a spectrometric borehole gamma-gamma probe for ash determination in coal. The measurements are carried out on three coal samples with different ash contents. The best configuration of the probe was established. Several spectral parameters were tested and selected in order to find a good dependence on the ash content of coal samples. (author) 3 figs., 5 refs

130

Errors of radioisotope ash-meters due to variations of coal density and iron content  

International Nuclear Information System (INIS)

Presented is the technique of calculation of radioisotope ash-meter errors which permits to take into consideration correlations between coal density pho and ash content Asup(c), and between iron content in coal CsUb(Fe) and ash content. Results of parallel analysis of AsUp(c) and Csub(Fe) and rho in any arbitrary selected coal samples with different ash content, iron content and density can be initial data for the calculation. The calculation results are recommended to be used for ash-meter calibration

131

Flotation of coal fines as hydrophobic flocs for ash rejection  

Energy Technology Data Exchange (ETDEWEB)

The flotation of coal fines in the form of hydrophobic flocs, which is termed floc-flotation, for rejecting fine mineral matters from coal slimes has been studied in this work. This process consists of dispersion, selective hydrophobic flocculation of fine organic matters, and flotation of the fines as flocs. This study was performed on two coal slimes from China, namely Taixi anthracite and Tongshan coking coal. The experimental results have shown that floc-flotation not only strongly increased the combustible recovery, but also greatly lowered the ash remaining in cleaned coals, compared with conventional flotation in the same reagent additions. This effect closely correlated with the size of flocculated organic matter. The larger were the flocs, the stronger the effect was. Also, it was found that flocculated coal fines had a much higher flotation rate than dispersed fines. In addition, the main parameters of the floc-flotation process, namely nonpolar oil addition and slurry conditioning in the hydrophobic flocculation step were experimentally studied.

Song, S.; Zhang, Y.; Wu, K.; Lopez-Valdivieso, A.; Lu, S. [University of Autonoma San Luis Potosi, San Luis Potosi (Mexico)

2004-07-01

132

Field studies of the leachability of aged brown coal ash.  

Science.gov (United States)

The environmental management of ash produced from the brown coal power stations of the Latrobe Valley region of Australia has been studied. Current practice consists of slurrying fly and bottom ash, a short distance to an ash disposal pond. However, storage facilities are approaching capacity and alternative ash management strategies are required in the near future. Initially, the ash produced within the power stations is known to possess a large soluble mass, which can leach rapidly to generate a saline leachate with minor trace metal content. After slurrying and deposition within the ash pond, it has been demonstrated that the soluble mass is significantly lower and the ash can be considered as aged or "leached" ash - a more benign waste that meets the criteria for fill material. In order to assess the long-term behaviour of the leached ash and its suitability for co-disposal in engineered sites within overburden dumps, two field cells were constructed and monitored over a period of 1 year. Each cell was 5 x 5 m in area, 3-m deep and HDPE lined with a coarse drainage layer and leachate collection pipe. The first cell only collected natural rainfall and was known as the Dry Cell. The second cell had an external tank of 5000 l installed (200-mm rainfall equivalent) and water was spray-irrigated regularly to simulate higher rainfall and accelerate the leaching process. The cumulative inflow and outflow for each cell has been calculated using a linear relationship and the leachate quality was monitored over time. The results demonstrate that the ash behaves as an unsaturated porous material, with the effect of evaporation through the profile being dominant and controlling the production of leachate. The leachate quality was initially moderately saline in both cells, with the concentration dropping by nearly 95% in the Wet Cell by the end of the field study. The leachate chemistry has been analysed using the PHREEQC geochemical model. The log activity plots of various species suggest the mineralogical controls on these species in leachate. The full results from this study are presented. PMID:10936533

Mudd, G M; Kodikara, J

2000-09-15

133

Remediação de drenagem ácida de mina usando zeólitas sintetizadas a partir de cinzas leves de carvão / Remediation of acid mine drainage using zeolites synthesized from coal fly ash  

Scientific Electronic Library Online (English)

Full Text Available [...] Abstract in english Zeolitic material was synthesized from coal fly ashes (baghouse filter fly ash and cyclone filter fly ash) by hydrothermal alkaline activation. The potential application of the zeolitic product for decontamination of waters from acid mine drainage was evaluated. The results showed that a dose of 30 [...] g L-1 of zeolitic material allowed the water to reach acceptable quality levels after treatment. Both precipitation and cation-exchange processes accounted for the reduction in the pollutant concentration in the treated waters.

Denise Alves, Fungaro; Juliana de Carvalho, Izidoro.

2006-07-01

134

Remediação de drenagem ácida de mina usando zeólitas sintetizadas a partir de cinzas leves de carvão Remediation of acid mine drainage using zeolites synthesized from coal fly ash  

Directory of Open Access Journals (Sweden)

Full Text Available Zeolitic material was synthesized from coal fly ashes (baghouse filter fly ash and cyclone filter fly ash by hydrothermal alkaline activation. The potential application of the zeolitic product for decontamination of waters from acid mine drainage was evaluated. The results showed that a dose of 30 g L-1 of zeolitic material allowed the water to reach acceptable quality levels after treatment. Both precipitation and cation-exchange processes accounted for the reduction in the pollutant concentration in the treated waters.

Denise Alves Fungaro

2006-07-01

135

Study on the ash fusion temperatures of coal and sewage sludge mixtures  

Energy Technology Data Exchange (ETDEWEB)

The coal, sewage sludge, water and chemical additives are milled to produce coal-sludge slurry as a substitute for coal-water slurry in entrained-flow gasification, co-gasification of coal and sewages sludge can be achieved. The ash fusion temperature is an important factor on the entrained-flow gasifier operation. In this study, the ash fusion temperatures (DT, ST, HT and FT) of three kinds of coals (A, B and C), two kinds of sewage sludges (W1 and W2) and series of coal-sewage blends were determined, and the mineral composition during the ash melting process was analyzed by X-ray diffraction (XRD). The results showed that the ash fusion temperatures of most coal-sewage blends are lower than those of the coals and sewage sludges. The ashes have different mineral composition at different temperature during the heating process. It was found that the mineral composition of AW1 blend ash is located in the low-temperature eutectic region of the ternary phase diagram of SiO{sub 2}-Al{sub 2}O{sub 3}-CaO. The minerals found in BW1 blend ash are almost the same as those in B coal ash. Kyanite is detected in CW1 blend ash, which results in the ash fusion temperatures of CW1 blend ash higher than those of C coal. We found that sodium mineral matters are formed because of NaOH added to W2, which can reduce the ash fusion temperature of coal-sewage blends. 27 refs., 6 figs., 2 tabs.

Li Weidong; Li Ming; Li Weifeng; Liu Haifeng [East China University of Science and Technology, Shanghai (China). Key Laboratory of Coal Gasification of Ministry of Education

2010-07-15

136

Prevention of trace and major element leaching from coal combustion products by hydrothermally-treated coal ash  

Energy Technology Data Exchange (ETDEWEB)

The most important structural components of coal ash obtained by coal combustion in 'Nikola Tesla A' power plant located near Belgrade (Serbia) are amorphous alumosilicate, alpha-quartz, and mullite. The phase composition of coal ash can be altered to obtain zeolite type NaA that crystallizes in a narrow crystallization field (SiO{sub 2}/Al{sub 2}O{sub 3}; Na{sub 2}O/SiO{sub 2}; H{sub 2}O/Na{sub 2}O ratios). Basic properties (crystallization degree, chemical composition, the energy of activation) of obtained zeolites were established. Coal ash extracts treated with obtained ion-exchange material showed that zeolites obtained from coal ash were able to reduce the amounts of iron, chromium, nickel, zinc, copper, lead, and manganese in ash extracts, thus proving its potential in preventing pollution from dump effluent waters.

Adnadjevic, B.; Popovic, A.; Mikasinovic, B. [University of Belgrade, Belgrade (Serbia). Dept. of Chemistry

2009-07-01

137

Material and structural characterization of alkali activated low-calcium brown coal fly ash  

International Nuclear Information System (INIS)

The waste low-calcium Czech brown coal fly ash represents a considerable environmental burden due to the quantities produced and the potentially high content of leachable heavy metals. The heterogeneous microstucture of the geopolymer Mn [-(Si-O)z-Al-O]n.wH2O, that forms during the alkaline activation, was examined by means of microcalorimetry, XRD, TGA, DSC, MIP, FTIR, NMR MAS (29Si, 27Al, 23Na), ESEM, EDS, and EBSD. The leaching of heavy metals and the evolution of compressive strength were also monitored. The analysis of raw fly ash identified a number of different morphologies, unequal distribution of elements, Fe-rich rim, high internal porosity, and minor crystalline phases of mullite and quartz. Microcalorimetry revealed exothermic reactions with dependence on the activator alkalinity. The activation energy of the geopolymerization process was determined as 86.2 kJ/mol. The X-ray diffraction analysis revealed no additional crystalline phases associated with geopolymer formation. Over several weeks, the 29Si NMR spectrum testified a high degree of polymerization and Al penetration into the SiO4 tetrahedra. The 23Na NMR MAS spectrum hypothesized that sodium is bound in the form of Na(H2O)n rather than Na+, thus causing efflorescence in a moisture-gradient environment. As and Cr6+ are weakly bonded in the geopoly>6+ are weakly bonded in the geopolymer matrix, while excellent immobilization of Zn2+, Cu2+, Cd2+, and Cr3+ are reported.

138

Effects of the addition of oil shale ash and coal ash on physic-chemical properties of CPJ45 cement  

OpenAIRE

We focused our research on recycling industrial wastes, fly ash (F.A), bottom ash (B.A) and oil shale ash (S.A) in cement production. The study concerns physico-chemical characterization of these products and the influence of their addition on the mechanical proprieties of the CPJ45 cement. XRF allowed us to rank the three additives used according to their contents on major oxides. Coal ashes belong to the class F, and thus possess poozzolanic properties and oil shale ash belongs to the class...

Nabih K.; Kada M.K.; Hmiri M.; Hamsi N.

2014-01-01

139

An appraisal of the potential use of fly ash for reclaiming coal mine spoil.  

Science.gov (United States)

Growing dependence on coal-fired power plants for electrical generation in many countries presents ongoing environmental challenges. Burning pulverized coal in thermal power plants (TPPs) generates large amounts of fly ash (FA) that must be disposed of or otherwise handled, in an environmentally-sound manner. A possible option for dealing with fly ash is to use it as an amendment for mine spoil or other damaged soil. It has been demonstrated through studies in India and other countries that FA alone or in combination with organic or inorganic materials can be used in a productive manner for reclamation of mine spoil. The characteristics of FA, including silt-sized particles, lighter materials with low bulk density (BD), higher water holding capacity, favorable pH and significant concentrations of many essential plant nutrients, make it a potentially favorable amendment for mine spoil reclamation. Studies have indicated that the application of FA has improved the physical, chemical and biological qualities of soil to which it is applied. The release of trace metals and soluble salts from FA could be a major limitation to its application. This is particularly true of fresh, un-weathered FA or acidic FA, although perhaps not a concern for weathered/pond ash or alkaline FA. Some potential contaminants, especially metals and other salt ions, could be immobilized and rendered biologically inert by the addition of certain inorganic and organic amendments. However, in view of the variability in the characteristics of FAs that are associated with location, feed coal, combustion conditions and other factors, the suitability of a particular FA for a specific soil/mine spoil needs to be critically evaluated before it is applied in order to maximize favorable results and eliminate unexpected consequences. FA generated in India tends to be mostly alkaline, with lower levels of trace elements than are often found in FAs from other countries. The concentrations of potential chemical stressors, predominantly metals, in Indian FAs are often less than established or proposed permissible limits and are thus better suited for soil application. A major logistic limitation to the use of FA could be the cost involved in transport of ash from production to utilization sites. PMID:19914766

Ram, Lal C; Masto, Reginald E

2010-01-01

140

Analysis of natural radionuclides in coal, slag and ash in coal-fired power plants in Serbia  

OpenAIRE

The radioactivity monitoring in the “Nikola Tesla”, “Kolubara”, “Morava” and “Kostolac” coal-fired power plants was performed by the Radiation and Environmental Protection Laboratory, Vin?a Institute of nuclear sciences in the period 2003-2010. Monitoring included the analysis of soil, water, flying ash, slag, coal and plants. This paper presents the results of the radioactivity analysis of coal, ash and slag samples. Naturally occurring radionuclides 226Ra, 232Th, 40K,...

Jankovi? M.M.; Todorovi? D.J.; Nikoli? J.D.

2011-01-01

141

Study of coal extraction into 2 rings aromatic solventsolvent de-ashing for HyperCoal production  

Energy Technology Data Exchange (ETDEWEB)

In order to reduce the CO{sub 2} emission, a new gas turbine combined cycle power generation system has been developing. It is named HyperCoal project supported by NEDO. HyperCoal is an ash and alkali free coal, which can be directly fired in the high efficiency gas turbine generation system. It means the net power output of power plant will be largely increased (48%) compare to that of conventional PCF power plant (36%). This project consists of three fundamental studies, one is the process development to produce HyperCoal, second is the designing of the generation system to utilize HyperCoal and the last is the LCA study of total CO{sub 2} emission. Solvent de-ashing technique is adopted to produce the ash free coal. Coal is dissolved into two rings aromatic solvent, and the insoluble residue is removed by gravity settling and filtration. This paper reports the results of the fundamental studies to investigate the influences of coal extraction conditions, such as temperature, coal extraction time, coal concentration, and coal particle size. The temperature at 360-370{degree} C, the time in 40-60 min, and coal concentration lower than 40 % were optimized conditions for bituminous coals. The extraction rate were achieved almost 70 wt% with some kinds of coals. It was found that the coal extraction rate was related on the coal softening point. As the coal softening point becomes lower, the coal extraction rate becomes higher. Considering coal extraction mechanism under the optimized conditions, the temperature effects on the relaxation of coal aggregated structure, at the same time, some weak bonds in the structure are broken by thermal decomposition. Therefore, some hydrogen transfer inside the coal structure are required to stabilize the thermally generated radical fragments. It is suggested that the coal softening characteristic becomes an important factor to increase coal extraction rate. 3 refs., 10 figs., 2 tabs.

Okuyama, N.; Deguchi, T.; Shigehisa, T.; Shinozaki, S. [Kobe Steel, Ltd. (Japan). Coal & Energy Project Dept.

2002-07-01

142

Elemental characterization of coal, fly ash, and bottom ash using an energy dispersive X-ray fluorescence technique.  

Science.gov (United States)

A total of 18 elements viz. Si, Al, Fe, Ca, Mg, K, Na, Sr, V, Zn, Mn, Cr, Cu, Pb, Ni, Co, As and Cd were analyzed in coal, fly ash and bottom ash samples collected across India using an EDXRF technique. Various indices such as element enrichment ratio, enrichment factor (with respect to crustal average) and mineral composition were calculated. Around 95% of mass was reconstructed using the concentration of elements in this study for fly and bottom ash. PMID:24685495

Tiwari, M; Sahu, S K; Bhangare, R C; Ajmal, P Y; Pandit, G G

2014-08-01

143

Effect of mixes made of coal bottom ash and fly ash on the mechanical strength and porosity of Portland cement  

OpenAIRE

[EN] New additions to the cement are needed to achieve a more sustainable and durable construction material. Within this context, bottom ashes can be used as a main constituent of Portland cements when it is mixed in an optimized proportion with fly ashes. The mechanical characteristics of standarized mortars made of mixes of pulverized coal combustion bottom and fly ashes are studied. The mortars were made of ordinary Portland cement (CEM I 42.5 N) and mixes of bottom...

Argiz, C.; Sanjua?n, M. A.; Mene?ndez, E.

2013-01-01

144

Effects of the addition of oil shale ash and coal ash on physic-chemical properties of CPJ45 cement  

Directory of Open Access Journals (Sweden)

Full Text Available We focused our research on recycling industrial wastes, fly ash (F.A, bottom ash (B.A and oil shale ash (S.A in cement production. The study concerns physico-chemical characterization of these products and the influence of their addition on the mechanical proprieties of the CPJ45 cement. XRF allowed us to rank the three additives used according to their contents on major oxides. Coal ashes belong to the class F, and thus possess poozzolanic properties and oil shale ash belongs to the class C and possesses hydraulic and poozolanic properties. The crystalline phases constituting each ash were analysed by XRD. We observe in bottom ash the presence of quartz and mullite. The same crystals are found in fly ash with hematite and magnetite. Oil shale ash is composed of quartz, anhydrite, gehlenite, wollastonite and periclase. The microstructures of fly ash and bottom ash were studied using SEM. The bottom ash was composed respectively of fine particles that are generally irregularly shaped, their dimensions are between 5 and 28?m and of big particles(300 ?m. The EDX analysis coupled with an electronic microscope provided some information about the major elements that constitute our samples. The dehydrations of anhydrous and three days hydrated cement were examined by DSC. For hydrated cements we noticed endothermic peaks related to the dehydration of CSH, CH and decomposition of carbonates. The study of the mechanical properties of CPJ45 cement by adding different proportions of fly ash, bottom ash and oil shale ash helped clarifying the percentage of ash that leaded to improve the 28 days mechanical strength. The results show that the cements studied have their maximum mechanical resistance with the addition at 7% of fly ash or 10% of oil shale ash.

Nabih K.

2014-04-01

145

Utilization of blended fluidized bed combustion (FBC) ash and pulverized coal combustion (PCC) fly ash in geopolymer  

International Nuclear Information System (INIS)

In this paper, synthesis of geopolymer from fluidized bed combustion (FBC) ash and pulverized coal combustion (PCC) fly ash was studied in order to effectively utilize both ashes. FBC-fly ash and bottom ash were inter-ground to three different finenesses. The ashes were mixed with as-received PCC-fly ash in various proportions and used as source material for synthesis of geopolymer. Sodium silicate (Na2SiO3) and 10 M sodium hydroxide (NaOH) solutions at mass ratio of Na2SiO3/NaOH of 1.5 and curing temperature of 65 deg. C for 48 h were used for making geopolymer. X-ray diffraction (XRD), scanning electron microscopy (SEM), degree of reaction, and thermal gravimetric analysis (TGA) were performed on the geopolymer pastes. Compressive strength was also tested on geopolymer mortars. The results show that high strength geopolymer mortars of 35.0-44.0 MPa can be produced using mixture of ground FBC ash and as-received PCC-fly ash. Fine FBC ash is more reactive and results in higher degree of reaction and higher strength geopolymer as compared to the use of coarser FBC ash. Grinding increases reactivity of ash by means of increasing surface area and the amount of reactive phase of the ash. In addition, the packing effect due to fine particles also contributed to increase in strength of geopolymers.

146

Utilization of blended fluidized bed combustion (FBC) ash and pulverized coal combustion (PCC) fly ash in geopolymer.  

Science.gov (United States)

In this paper, synthesis of geopolymer from fluidized bed combustion (FBC) ash and pulverized coal combustion (PCC) fly ash was studied in order to effectively utilize both ashes. FBC-fly ash and bottom ash were inter-ground to three different finenesses. The ashes were mixed with as-received PCC-fly ash in various proportions and used as source material for synthesis of geopolymer. Sodium silicate (Na(2)SiO(3)) and 10M sodium hydroxide (NaOH) solutions at mass ratio of Na(2)SiO(3)/NaOH of 1.5 and curing temperature of 65 degrees C for 48h were used for making geopolymer. X-ray diffraction (XRD), scanning electron microscopy (SEM), degree of reaction, and thermal gravimetric analysis (TGA) were performed on the geopolymer pastes. Compressive strength was also tested on geopolymer mortars. The results show that high strength geopolymer mortars of 35.0-44.0MPa can be produced using mixture of ground FBC ash and as-received PCC-fly ash. Fine FBC ash is more reactive and results in higher degree of reaction and higher strength geopolymer as compared to the use of coarser FBC ash. Grinding increases reactivity of ash by means of increasing surface area and the amount of reactive phase of the ash. In addition, the packing effect due to fine particles also contributed to increase in strength of geopolymers. PMID:19854038

Chindaprasirt, Prinya; Rattanasak, Ubolluk

2010-04-01

147

Odorants and malodors associated with land application of biosolids stabilized with lime and coal fly ash.  

Science.gov (United States)

Malodor emissions limit public acceptance of using municipal biosolids as natural organic resources in agricultural production. We aimed to identify major odorants and to evaluate odor concentrations associated with land application of anaerobically digested sewage sludges (Class B) and their alkaline (lime and coal fly ash)-stabilized products (Class A). These two types of biosolids were applied at 12.6 tonnes ha(-1) (dry weight) to microplots of very fine clayey Vertisol in the Jezreel Valley, northern Israel. The volatile organic compounds (VOCs) emitted from the biosolids before and during alkaline stabilization and after incorporation into the soil were analyzed by headspace solid-phase microextraction followed by gas chromatography-mass spectrometry. Odor concentrations at the plots were evaluated on site with a Nasal Ranger field olfactometer that sniffed over a defined land surface area through a static chamber. The odors emitted by anaerobically digested sewage sludges from three activated sludge water treatment plants had one characteristic chemical fingerprint. Alkaline stabilization emitted substantial odors associated with high concentrations of ammonia and release of nitrogen-containing VOCs and did not effectively reduce the potential odor annoyance. Odorous VOCs could be generated within the soil after biosolids incorporation, presumably because of anaerobic conditions within soil-biosolids aggregates. We propose that dimethyl disulfide and dimethyl trisulfide, which seem to be most related to the odor concentrations of biosolids-treated soil, be used as potential chemical markers for the odor annoyance associated with incorporation of anaerobically digested sewage sludges. PMID:21869502

Laor, Yael; Naor, Moshe; Ravid, Uzi; Fine, Pinchas; Halachmi, Ilan; Chen, Yona; Baybikov, Rima

2011-01-01

148

Utilization of coal ash/coal combustion products for mine reclamation  

International Nuclear Information System (INIS)

Society's demand for an inexpensive fuel, combined with ignorance of the long term impacts, has left numerous scars on the Pennsylvania landscape. There are over 250,000 acres of abandoned surface mines with dangerous highwalls and water filled pits. About 2,400 miles of streams do not meet water quality standards because of drainage from abandoned mines. There are uncounted households without an adequate water supply due to past mining practices. Mine fires and mine subsidence plague many Pennsylvania communities. The estimated cost to reclaim these past scars is over $15 billion. The beneficial use of coal ash in Pennsylvania for mine reclamation and mine drainage pollution abatement projects increased during the past ten years. The increase is primarily due to procedural and regulatory changes by the Department of Environmental Protection (DEP). Prior to 1986, DEP required a mining permit and a separate waste disposal permit for the use of coal ash in backfilling and reclaiming a surface mine site. In order to eliminate the dual permitting requirements and promote mine reclamation, procedural changes now allow a single permit which authorize both mining and the use of coal ash in reclaiming active and abandoned pits. The actual ash placement, however, must be conducted in accordance with the technical specifications in the solid waste regulations

149

Mosses accumulate heavy metals from the substrata of coal ash  

Directory of Open Access Journals (Sweden)

Full Text Available Plants that are able to accumulate and tolerate extraordinarily high concentrations of heavy metals (hyperaccumulators can be used for phytoremediation (removal of contaminants from soils or phytomining (growing a crop of plants to harvest the metals. Two moss species, Bryum capillare Hedw. and Ceratodon purpureus Hedw., were tested as potential phytoremedies under in vivo conditions on a coal ash disposal site in the surroundings of Obrenovac (NW Serbia. The content of various heavy metals (iron, manganese zinc, lead, nickel, cadmium, and copper in the mosses and substrata were investigated over a period of three years. Iron and zinc were found to have the highest concentration in the mosses.

Vukojevi? Vanja

2005-01-01

150

Hydrothermal alkaline treatment of oil shale ash for synthesis of tobermorites  

Energy Technology Data Exchange (ETDEWEB)

The hydrothermal alkaline activation of the oil shale fly ash was studied using SEM/EDX, XRD and {sup 29}Si and {sup 27}Al high-resolution MAS-NMR spectra. The silicon in the original fly ashes was completely converted into calcium-alumino-silicate hydrates, mainly into 1.1 nm tobermorite structure during 24 h treatment under hydrothermal conditions at 160{sup o}C in the presence of NaOH. The local structure of synthesized tobermorite samples implies long silicate chains with small number of bridging sites. The results obtained in the study prove that the oil shale fly ash can be used for production of Al-substituted tobermorites. 27 refs., 11 figs., 2 tabs.

Janek Reinik; Ivo Heinmaa; Jyri-Pekka Mikkola; Uuve Kirso [National Institute of Chemical Physics and Biophysics, Tallinn (Estonia)

2007-03-15

151

Stabilisation of acid generating waste rock with fly ash : immobilization of arsenic under alkaline conditions  

Energy Technology Data Exchange (ETDEWEB)

This study evaluated the potential for using fly ash as an alkaline material for increasing the pH and decreasing arsenic leaching from highly acidic mine waste. A wood ash sample known to contain high concentrations of both calcium and barium was tested with highly acidic mine waste samples that leached approximately 200 mg/L of arsenic at a liquid/solid ratio of 2. Samples were mixed with the fly ash. Control samples consisted of only mine waste, while the amended samples contained 10 g of mine waste and 10 g of wood ash. Ultra pure water was used as a leachant for both systems until the liquid-solid ratio that corresponded to 900 years of drainage for a waste pile that was 3 m high with an annual run-off of 300 mm. Results of the experimental study showed that the pH in the control increased from 1.7 to 2.7, while the pH in the amended system decreased from 12.6 to 11.5. Initial concentrations of arsenic decreased by almost 3 orders of magnitude in the amended systems. Co-precipitation with the iron, and the calcium arsenate precipitation process were identified as the principal arsenic immobilization mechanisms. The study demonstrated that under the right chemical conditions, alkaline amendments can be used to reduce arsenic leaching from mine wastes. 5 refs., 2 tabs., 1 fig.

Backstrom, M. [Orebro Univ. (Sweden). Man-Technology Environment Research Centre; Sartz, L. [Bergslagen, Kopparberg (Sweden)

2010-07-01

152

Alkaline modified oil shale fly ash: optimal synthesis conditions and preliminary tests on CO2 adsorption.  

Science.gov (United States)

Environmentally friendly product, calcium-silica-aluminum hydrate, was synthesized from oil shale fly ash, which is rendered so far partly as an industrial waste. Reaction conditions were: temperature 130 and 160°C, NaOH concentrations 1, 3, 5 and 8M and synthesis time 24h. Optimal conditions were found to be 5M at 130°C at given parameter range. Original and activated ash samples were characterized by XRD, XRF, SEM, EFTEM, (29)Si MAS-NMR, BET and TGA. Semi-quantitative XRD and MAS-NMR showed that mainly tobermorites and katoite are formed during alkaline hydrothermal treatment. Physical adsorption of CO(2) on the surface of the original and activated ash samples was measured with thermo-gravimetric analysis. TGA showed that the physical adsorption of CO(2) on the oil shale fly ash sample increases from 0.06 to 3-4 mass% after alkaline hydrothermal activation with NaOH. The activated product has a potential to be used in industrial processes for physical adsorption of CO(2) emissions. PMID:21943923

Reinik, Janek; Heinmaa, Ivo; Kirso, Uuve; Kallaste, Toivo; Ritamäki, Johannes; Boström, Dan; Pongrácz, Eva; Huuhtanen, Mika; Larsson, William; Keiski, Riitta; Kordás, Krisztián; Mikkola, Jyri-Pekka

2011-11-30

153

Characterization of iron-bearing phases in coal and their ash  

International Nuclear Information System (INIS)

Moessbauer spectroscopy and X-ray diffraction techniques have been used to characterize the iron-bearing phases in coal and their ash formed at 500deg C. The analysis of the Moessbauer parameters and X-ray diffraction results show the presence of siderite, illite, pyrite and kaolinite in coal and hematite in ash as dominant minerals. (orig.)

154

Radon and thoron flux densities from some of NSW coal ash dams  

International Nuclear Information System (INIS)

The use of coal as an energy source can cause some potential environmental and human health hazards associated with radionuclides mobilized by the coal fuel cycle. The objective of this study was to assess environmental significance of radon and thoron emissions from New South Wales coal ash storage dams operated by Pacific Power. To achieve this objective radon and thoron flux densities were measured from selected ash dams and mine spoil areas. It was found that: (i) ash dams currently in operation exhibit significantly lower flux densities than average values for Australian soils, and (ii ash dams under rehabilitation and mine spoils have flux densities comparable to Australian soil. 18 refs., 2 tabs

155

Radiological Considerations in the Production of Lightweight Concrete Based on Coal Ashes  

International Nuclear Information System (INIS)

The common disadvantage of using high volumes of coal ashes (both bottom ash and fly ash) in lightweight concrete production is the presence in the ashes of trace amounts of heavy metals and natural radionuclides such as 226Ra, 232Th and 40K. Therefore, coal ashes are classified in many cases as a material with enhanced radioactivity. Accordingly, the use of coal ashes in lightweight concrete must comply with requirements of international recommendations and national legislations. Over the past decade, a series of studies were performed at the Ariel University Center of Samaria (Ariel, Israel) in search for optimum solutions for the use of coal ashes (both fly and bottom ashes) in the lightweight concrete technology. These studies included investigations of scientific and engineering issues related to the radiological and engineering aspects of the utilization of coal ashes in the building industry, as described in this paper. Special attention was paid to a problem of producing ecologically-friendly concrete based on coal ashes. Our product contributes significantly to the advancement of material recirculation by using in addition to fly ash, also bottom ash. This significant by product of coal combustion is used at present predominantly for construction beddings, structural fills. Utilization of fly ash for concrete production contributes to the reduction of the potential damage to the environment that can be caused by the accumulatinment that can be caused by the accumulation of coal ashes in piles and ponds near power stations. Bonding the ash particles (in safe quantities) with the cement in concrete articles and structures reduces the potential exposure of humans to internal radiation by avoiding the penetration of fine ash particles to human internal organs. In order to lower the radioactivity of concrete resulting from the use of coal ashes, we added to the concrete mixture calculated amounts of unprocessed crushed sand (UCS). This material is denser and is very low in radioactivity. UCS is a by-product of crushing limestone or dolomite in the process of crushed stone production at stone quarries. The Ariel University Center of Samaria (Ariel, Israel) performed during the last decade a series of studies, searching for optimum ways for the utilization of coal ashes in the production of economically friendly lightweight concrete. These studies were related to a variety of scientific and engineering issues as described in this presentation

156

Leaching of elements from coal fly ash: Assessment of its potential for use in filling abandoned coal mines  

Energy Technology Data Exchange (ETDEWEB)

Leaching of ten elements - namely, Fe, Mn, Ca, Na, K, Cu, Cr, Zn, As and Pb - from four fly ash samples collected from four different coal-fired thermal power plants in West Bengal, India, has been reported. The leaching conditions were selected to broadly simulate that of surface coal mines in order to estimate the usefulness of the materials for back-filling of abandoned mines and to assess the possibility of contamination of the sites by release of heavy metal ions. Sequential batch leaching consisted of four cycles each of seven days duration; the long-term leaching continued over a period of 180 days. The starting pH of the leaching solutions ranged from strongly acidic to strongly basic. The leaching pattern and its dependence on the pH as well as the solid-liquid ratio have been critically analyzed. A much higher mobility of the elements have been expectedly observed at a low pH. Less leaching is found at a high pH except for arsenic. The mobilization pattern is strongly governed by the well-known phenomenon of dissolution and re-precipitation of iron with co-precipitation of a series of elements depending upon the pH of the medium. Extraction equilibrium was reached for Ca, Fe, Na and Zn at certain pH values. A monotonic trend of release for the elements Mn, K, Cu, Pb, Cr and As persisted over the long-term leaching period of 180 days. The alkalinity or the calcium content of an ash sample greatly determines the leaching pattern if the solution pH is neutral or mildly acidic. It appears that the risk pollution of ground water as well as of surface water may not be avoidable if fly ash alone is used for mine back-filling in an environment where acid mine drainage is prominent. Nevertheless blending with lime to enhance the alkalinity appears to offer a practical solution to the problem. 45 refs., 10 figs., 3 tabs.

Binay K. Dutta; Swapan Khanra; Durjoy Mallick [Petroleum Institute, Abu Dhabi (UAE)

2009-07-15

157

Utilization of sludge and fly ash from preparation plants of North Bohemia coal mines  

Energy Technology Data Exchange (ETDEWEB)

Studies separation of coal slurries and possible uses of dried brown coal sludge from coal preparation plants in Czechoslovakia. This dried preparation plant sludge has a 55-70% ash content. Further properties are given. Tests were carried out to elaborate efficient and economic water removal from the slurry. Various commercial flocculants, including Magnafloc, Superfloc, Filtrafloc and Preastol were applied. The slurry was separated into a low ash and high ash fraction. The low ash fraction (22.5% ash content, 17 MJ/kg calorific value, 21% moisture) is considered suitable for fluidized bed combustion, the high ash fraction (83% ash, 4.4 MJ/kg) can be used as additive to clay for production of bricks. 3 refs.

Malina, B.; Chytka, L.; Derkac, M. (Vyzkumny Ustav pro Hnede Uhli, Most (Czechoslovakia))

1992-12-01

158

Mutagenicity and cytotoxicity of coal fly ash from fluidized-bed and conventional combustion  

Energy Technology Data Exchange (ETDEWEB)

Two respirable coal fly-ash samples (<3MUm) were evaluated for physical properties, chemical composition and biological activity, including cytotoxicity and mutagenicity. The two fly-ash samples were collected from a pressurized fluidized-bed combustion miniplant and from a conventional-combustion plant, both burning eastern US coal. The two samples were found to have different physical and chemical properties. Both samples were toxic in two mammalian cell systems, with fluidized bed combustion fly ash showing higher toxicity in both assay systems. For conventional-combustion fly ash, no mutagenicity was detected in bioassay of the whole particles. A series of organic solvents was employed to identify the most efficient solvent for removing mutagens from coal fly ash. Extracts of fluidized-bed combustion fly ash were found to be mutagenic when dichloromethane, acetone or cyclohexane were employed: much lower mutagenic activity was found in dichloromethane and acetone extracts of conventional combustion fly ash.

Mumford, J.L.; Lewtas, J.

1982-10-01

159

Fractionation and transport of nutrients among coal ash residues and in soil covered with fly ash-amended organic compost  

Energy Technology Data Exchange (ETDEWEB)

Coal-fired power plants generate different types of ash residues and discharge small particles and vapours to the atmosphere. The ash residues which account for the major part of the byproducts are collected and stored as bottom ash, boiler ash, and fly ash, weathered ash and ash in lagoon. Analysis of water extracts of these residues will reveal how the nutrients are distributed in these residues and transported to aquatic systems. Equally interesting is the study of the downward movement of nutrients in soil treated with fly ash-amended organic compost when used as a manure for agricultural crops. In this work, water extracts of different types of ash residues and eluates from descending ports of an experimental column of soil at different depths were also analyzed. The results showed that there is considerable difference in the efficiency of removal and deposition of nutrients on different residues collected from the power plant and stored outside. Bottom ash was found to accumulate K, N, and S while Ca is enriched in ash from lagoon. Transition metals such as Zn, Mn, and Cu are concentrated in weathered ash. The concentration of most of the nutrients was found to decrease, in column experiments, as a function of depth and level to a depth of 80 cm. 12 refs., 5 tabs.

Menon, M.P.; Sajwan, K.S.; Ghuman, G.S.; James, J.; Chandra, K.; Bacon, B. (Savannah State College, Savannah, GA (United States). School of Sciences and Technology)

1993-07-01

160

Radioactivity in coal, ashes and selected wastewaters from Canadian coal-fired steam electric generating stations  

International Nuclear Information System (INIS)

Coal is known to contain naturally occurring radioactive elements and there has been speculation that as a results, coal-fuelled power generation stations may be significant emitters of these substances. In this report, the subject of radioactivity is introduced. The kinds of radioactive substances which occur naturally in coal formations, the nature of their emissions and the existing information on their behaviour and their effects on environmental organisms are also reviewed. The results of an examination of levels of alpha, beta and gamma radiaton levels, and the substances which produce them in coals, fly ashes, bottom ashes and related wastewaters at six Canadian coal-fuelled power stations are presented. Difficulties in studies of this nature and the potential effects of these releases on organisms in the adjacent aquatic environment are discussed. Existing and potential technologies for the removal of these substances from wastewaters are examined. In general the releases in wastewaters from the six stations were found to be lower than those known to cause short-term or acute biological effects. The potential for long-term effects from such low-level releases could not be accurately assessed because of the paucity of information. A number of recommendations for: improvements in further studies of this nature; the further examination of the fate of naturally occurring radionuclides in the environment; and the determination of the long-term effects of low levels of naturally occurring radioactive substances on aquatic organisms, are made

161

Mineralogy and microstructure of sintered lignite coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

Lignite coal fly ash from the 'Nikola Tesla' power plant in Yugoslavia has been characterised, milled, compacted and sintered to form monolithic ceramic materials. The effect of firing at temperatures between 1130 and 1190{sup o}C on the density, water accessible porosity, mineralogy and microstructure of sintered samples is reported. This class C fly ash has an initial average particle size of 82 {mu}m and contains siliceous glass together with the crystalline phases quartz, anorthite, gehlenite, hematite and mullite. Milling the ash to an average particle size of 5.6 m, compacting and firing at 1170{sup o}C for 1 h produces materials with densities similar to clay-based ceramics that exhibit low water absorption. Sintering reduces the amount of glass, quartz, gehlenite and anhydrite, but increases formation of anorthite, mullite, hematite and cristobalite. SEM confirms the formation of a dense ceramic at 1170{sup o}C and indicates that pyroplastic effects cause pore formation and bloating at 1190{sup o}C. 23 refs., 6 figs., 2 tabs.

Marina Ilic; Christopher Cheeseman; Christopher Sollars; Jonathan Knight [Faculty of Technology and Metallurgy, Belgrade (Yugoslavia)

2003-02-01

162

Monitor of ash content of coal with X-ray source  

International Nuclear Information System (INIS)

The coal ash monitor is used on-line to measure the ash content of raw, washed and blended coals. The instrument consists of a presentation unit and electronic unit. In the presentation unit a compact layer of coal is formed and there is also a radiation measuring system. A plutonium 238 source is used and the backscattered X-rays are detected by a proportional counter. The count rate is processed in the electronic unit and displayed as the ash percentage in the coal. A wide range of Polish coals was analysed. The monitor was tested in a power plant over the period of one year. The ash content in the coal analysed was in the range 5 to 50%. The gauge readings were compared with the pyrolysis results. An accuracy of 3.2% (95% confidence limit) was reached. These results were not corrected for the free moisture content which varied in the range 5 to 15 %. (author)

163

Monitor of ash content of coal with X-ray source  

Energy Technology Data Exchange (ETDEWEB)

The coal ash monitor is used on-line to measure the ash content of raw, washed and blended coals. The instrument consists of a presentation unit and electronic unit. In the presentation unit a compact layer of coal is formed and there is also a radiation measuring system. A plutonium 238 source is used and the backscattered X-rays are detected by a proportional counter. The count rate is processed in the electronic unit and displayed as the ash percentage in the coal. A wide range of Polish coals was analysed. The monitor was tested in a power plant over one year. The ash content in the coal analysed was in the range 5 to 50%. The gauge readings were compared with the pyrolysis results. An accuracy of 3.2% (95% confidence limit) was obtained. These results were uncorrected for the free moisture content which varied in the range 5-15%. 5 references.

Wawrzonek, L.

1983-06-01

164

JV Task 120 - Coal Ash Resources Research Consortium Research  

Energy Technology Data Exchange (ETDEWEB)

The Coal Ash Resources Research Consortium{reg_sign} (CARRC{reg_sign}, pronounced 'cars') is the core coal combustion product (CCP) research group at the Energy & Environmental Research Center (EERC). CARRC focuses on performing fundamental and applied scientific and engineering research emphasizing the environmentally safe, economical use of CCPs. CARRC member organizations, which include utilities and marketers, are key to developing industry-driven research in the area of CCP utilization and ensuring its successful application. The U.S. Department of Energy is a partner in CARRC through the EERC Jointly Sponsored Research Program, which provides matching funds for industrial member contributions and facilitates an increased level of effort in CARRC. CARRC tasks were designed to provide information on CCP performance, including environmental performance, engineering performance, favorable economics, and improved life cycle of products and projects. CARRC technical research tasks are developed based on member input and prioritization. CARRC special projects are developed with members and nonmembers to provide similar information and to support activities, including the assembly and interpretation of data, support for standards development and technology transfer, and facilitating product development and testing. CARRC activities from 2007 to 2009 included a range of research tasks, with primary work performed in laboratory tasks developed to answer specific questions or evaluate important fundamental properties of CCPs. The tasks were included in four categories: (1) Environmental Evaluations of CCPs; (2) Evaluation of Impacts on CCPs from Emission Controls; (3) Construction and Product-Related Activities; and (4) Technology Transfer and Maintenance Tasks. All tasks are designed to work toward achieving the CARRC overall goal and supporting objectives. The various tasks are coordinated in order to provide broad and useful technical data for CARRC members. Special projects provide an opportunity for non-CARRC members to sponsor specific research or technology transfer consistent with CARRC goals. This report covers CARRC activities from January 2007 through March 2009. These activities have been reported in CARRC Annual Reports and in member meetings over the past 2 years. CARRC continues to work with industry and various government agencies with its research, development, demonstration, and promotional activities nearing completion at the time of submission of this report. CARRC expects to continue its service to the coal ash industry in 2009 and beyond to work toward the common goal of advancing coal ash utilization by solving CCP-related technical issues and promoting the environmentally safe, technically sound, and economically viable management of these complex and changing materials.

Debra Pflughoeft-Hassett; Loreal Heebink; David Hassett; Bruce Dockter; Kurt Eylands; Tera Buckley; Erick Zacher

2009-03-28

165

Studying the melting behavior of coal, biomass, and coal/biomass ash using viscosity and heated stage XRD data  

DEFF Research Database (Denmark)

The use of biomass for power generation can result in significant economical and environmental benefits. The greenhouse emissions can be reduced as well as the cost of the produced electricity. However, ash-related problems, including slagging, agglomeration, and corrosion, can cause frequent unscheduled shutdowns, decreasing the availability and increasing the cost of the produced power. In addition, the fouling of the heat exchange surfaces reduces the system efficiency. In this work the melting and rheological properties of various biomass and biomass/ coal ash samples were studied by using a high-temperature rotational viscometer and a hot stage XRD. The produced data were used to calculate the operating temperature of a pilot-scale entrained flow reactor during the cocombustion of biomass/ coal samples in order to ensure the slag flow and to avoid corrosion of the walls due to liquid slag/metal interaction. Biomass ash proved to have significantly different melting behavior compared to that of the coal ash. Furthermore, the addition of biomass to coal ash led to lower viscosity and subsequently to higher stickiness of the produced ash particles. The melting behavior of the slag generated by the cocombustion tests appeared to be somewhat different compared to that of the laboratory-prepared ash samples. The heated stage XRD data provide useful information regarding the reactions among the various ash compounds and the phase transformations during the heating and cooling of the ash samples and helped the explanation of the produced viscosity curves.

Arvelakis, Stelios; Folkedahl, B.

2006-01-01

166

Natural radioactivity of coal and fly ash at the Nikola Tesla B TPP  

Directory of Open Access Journals (Sweden)

Full Text Available Serbian thermal power plants (TPPs produce siliceous fly ash from lignite in the quantity of approximately 6 million tons per year. The potential market for the use of fly ash is operational, but for the time being, only used by cement producers. Fly ash radioactivity could be one of the major points of concern when larger use of fly ash is planned, particularly in the Serbian construction industry. Radioactivity measurements have been conducted regularly for decades. This paper presents the results of a ten-year fly ash radioactivity measurements at the Nikola Tesla B TPP located in Obrenovac. In addition, the paper compares the natural radionuclides coal content data combusted by the Nikola Tesla B TPP boilers coming from the Kolubara Basin and ash created during coal combustion. Fly ash created in the Nikola Tesla TPPs boilers is characterised by the increased concentration of the natural radionuclides content compared to coal. This is the so-called technologically enhanced natural radioactivity (Technologically Enhanced Occurring Radioactive Material - TENORM of industrial waste, whereas the average specific activities: 232Th in coal amount to 25.2 Bq/kg, and in fly ash and coal 84.2 Bq/kg and 238U 38.3 Bq/kg, respectively. Following the obtained natural radionuclides content results it may be concluded that the Nikola Tesla B TPP ash may be disposed into the environment. Ash may be used also in the construction industry (civil engineering. In building construction applications, ash share as the additive to other building materials depends from its physical and chemical characteristics, as well as from the radionuclides activity: 266Ra, 232Th and 40K. Unlike the thermal power plants regularly (once a year testing the specific natural radionuclides activity in the combusted coal and boiler fly ash, Electric Power Industry of Serbia has not performed large-scale investigations of the natural radionuclides content in coal within the Kolubara Mining Basin. Natural radionuclides content in fly ash is compared to the combusted coal some 3 - 4 times higher and may present a limitation for applying ash in the construction industry. In view of the above, and considering the construction industry interests in using the Nikola Tesla B TPP ash, regular investigations of the natural radionuclides content in ash created in the thermal power plants should be carried out, together with the Kolubara Mining Basin coal combusted by the Nikola Tesla B TPP and other PE EPS thermal power plants. The current Kolubara Mining Basin coal characteristics investigation programme should be supplemented by the natural radionuclides content of the uranium (238U, 226Ra and thorium series (232Th and potassium 40 (40K.

Kisi? Dragica M.

2013-01-01

167

Selenium in onions grown in media amended with coal fly ashes collected with differing efficiencies  

Energy Technology Data Exchange (ETDEWEB)

Whether the particle size distribution of fly ash influences selenium uptake by onions grown on coal fly ash-amended growth media was investigated. Two fly ashes having differing percentages of finely sized particles were used as plant growth amendments at percentages in the media to yield equal concentrations of selenium. Selenium concentrations in the harvested onion bulbs were found to be independent of fly ash particle size distribution.

Gutenmann, W.H.; Doss, G.J.; Lisk, D.J. [Cornell University, Ithaca, NY (United States). New York State College of Agriculture and Life Sciences, Dept. of Fruit and Vegetable Science

1998-08-01

168

Enrichment and particle size dependence of polonium and other naturally occurring radionuclides in coal ash.  

Science.gov (United States)

Coal fired thermal power contributes 70% of power in India. Coal fired power generation results in huge amounts of fly ash and bottom ash of varying properties. Coal, which contains the naturally occurring radionuclides, on burning results in enrichment of these radionuclides in the ashes. In the present study, coal, bottom ash and fly ash samples collected from six coal-fired power plants in India were measured for (210)Po using alpha spectrometry and for natural U, (226)Ra, (232)Th and (40)K by an HPGe ?-ray spectrometer. (210)Po in fly ash ranged from 25.7 to 70 Bq/kg with a mean value of 40.5 Bq/kg. The range and mean activities of (238)U, (226)Ra, (232)Th, (40)K in fly ash were 38.5-101 (78.1), 60-105.7 (79), 20-125 (61.7) and 43.6-200 (100) Bq/kg respectively. Fly ash and bottom ash contains two to five times more natural radionuclides than feed coal. The results were compared with the available data from earlier studies in other countries. The effect of particle size on enrichment factor of the nuclides in fly ash was studied. (210)Po showed the largest size dependence with its concentration favoring the smaller particle size while (232)Th showed least size dependence. (238)U and (226)Ra showed behavior intermediate to that of (210)Po and (232)Th. Also the correlation between sulfur content of the feed coal and activity of (210)Po was investigated. Increased sulfur content in feed coal enhanced enrichment of (210)Po in ash. PMID:24813148

Sahu, S K; Tiwari, M; Bhangare, R C; Pandit, G G

2014-12-01

169

The partitioning behaviour of boron from tourmaline during ashing of coal  

Energy Technology Data Exchange (ETDEWEB)

Boron is an environmentally sensitive element that may be present in high concentrations in some coals. Three modes of occurrence for boron in coal are commonly recognised, namely, bound to the organic fraction, locked into clay minerals (mainly illite), and bound within the crystal lattice of tourmaline. The organically bound mode is generally considered to be the most likely. Following combustion in a pulverised fuel utility, boron is generally enriched in the fine fly ash waste, but in some cases, it may also escape with the flue gas, suggesting variable partitioning behaviour. There is concern that boron may be leached from fly ash disposal impounds at concentrations toxic to higher land plants. A coal sample from the D Seam of the Strongman No. 2 Mine, West Coast, South Island, New Zealand has been used to test the hypothesis that boron present in tourmaline is less volatile in coal combustion, implying that mode of occurrence is a key control on the partitioning behaviour of this element. Six sample subsets were doped with increasing amounts of ground tourmaline. One subsample from each set was analysed by prompt gamma INAA to determine the concentration of boron in the coal. Two subsamples were ashed at 1000 C. One ash sample from each set was analysed for boron, while the other ash sample was leached according to Australian standards. It was found that the relationship between boron in the doped coal and boron in the ash is approximately linear (with some losses noted during ashing), indicating boron present in tourmaline was substantially retained in the ash. Furthermore, no relationship was found between the boron content of the ash and boron leached from the ash samples by reagent water. The results suggest boron present in coal as tourmaline is retained in the ash and is unavailable to the environment following fly ash disposal.

Boyd, R.J. [James Cook University, Henderson, KY (Australia)

2002-12-01

170

A methodology to evaluate coal ash content using Siderite Moessbauer spectral area  

Energy Technology Data Exchange (ETDEWEB)

A methodology was used to evaluate Low Temperature Ash (LTA) and High Temperature Ash (HTA) through Moessbauer Spectroscopy (MS). Siderite was the only Moessbauer Spectral presenting a good correlation between the spectral area and the ash content obtained by LTA and HTA. The calibration curves obtained for HTA and LTA gave a correlation coefficient of 0.968 and 0.988, respectively. The LTA results present the best correlation, given that this process does not change the original mineral phases. This methodology was the advantageous for easily obtaining coal ash content, through curve ash content vs. MS area, without carrying out ashing processes. Short communication. 5 refs., 3 figs., 2 tabs.

G. Medina; J.A. Tabares; G.A. Perez Alcazara; J.M. Barraza [Universidad del Valle, Cali (Colombia). Department of Physics

2006-03-15

171

Emission Characteristics of NOx and Unburned Carbon in Fly Ash of Sub-bituminous Coal Combustion  

Science.gov (United States)

Sub-bituminous coal is considered to be one substitute fuel for bituminous coal. Since sub-bituminous coal contains more than 20% moisture, there are some problems with its utilization, such as a decrease in combustibility, high NOx emission and so on. This report describes the emission characteristics of NOx and unburned carbon in fly ash of sub-bituminous coal combustion through the use of a pulverized coal combustion test furnace. On the sub-bituminous coal combustion, ignition at the burner exit worsened and the combustion flame became diffused. Then, both NOx emission and the unburned carbon concentration in fly ash became high. In order to keep stable combustion and to form an effective NOx reduction flame, the swirl vane angle of secondary air was reduced and the Air/Coal ratio was lowered. As a result, the combustion flame became moderate, and both NOx emission and unburned carbon concentration in fly ash could be reduced.

Ikeda, Michitaka; Kozai, Yukitoshi; Makino, Hisao

172

Application of dry separative methods for decreasing content the residues unburned coal and separation Fe from black coal flies ash  

Directory of Open Access Journals (Sweden)

Full Text Available Main obstacle using of fly ashes in building, that is its main consumer, is the residue of unburned coal; it is expressed of loss onignition - LOI. In present, the valid STN and EU standard limits the content of LOI to 3 – 5 %, in national conditions maximum 7 %.Application of processing technologies also has to assure utilization of fly ash that provides a possibility of complex utilizationof individual products obtained by modification.By means of corona separation, based on different conductivity of individual fly ash elements, it is possible to separate unburnedcoal particles. The fly ash sample from black coal burning in melting boiler that was deposited on fly ash deposit, content of LOIof dielectric particle 6,45 % at 61 % weight yield was achieved. In the samples taken from dry taking of fly ash the non-conductingproduct contained 7,72 % of LOI at 73 % of weight yield.

František Ka?avský

2008-06-01

173

Trace and major element pollution originating from coal ash suspension and transport processes.  

Science.gov (United States)

Coal ash obtained by coal combustion in the "Nikola Tesla A" power plant in Obrenovac, near Belgrade, Yugoslavia, is mixed with water of the Sava river and transported to the dump. In order to assess pollution caused by leaching of some minor and major elements during ash transport through the pipeline, two sets of samples (six samples each) were subjected to a modified sequential extraction. The first set consisted of coal ash samples taken immediately after combustion, while the second set was obtained by extraction with river water, imitating the processes that occur in the pipeline. Samples were extracted consecutively with distilled water and a 1 M solution of KCl, pH 7, and the differences in extractability were compared in order to predict potential pollution. Considering concentrations of seven trace elements as well as five major elements in extracts from a total of 12 samples, it can be concluded that lead and cadmium do not present an environmental threat during and immediately after ash transport to the dump. Portions of zinc, nickel and chromium are released during the ash transport, and arsenic and manganese are released continuously. Copper and iron do not present an environmental threat due to element leaching during and immediately after the coal ash suspension and transport. On the contrary, these elements, as well as chromium, become concentrated during coal ash transport. Adsorbed portions of calcium, magnesium and potassium are also leached during coal ash transport. PMID:11341293

Popovic, A; Djordjevic, D; Polic, P

2001-04-01

174

Comparison of fly ash properties from Afsin-Elbistan coal basin, Turkey  

International Nuclear Information System (INIS)

Afsin-Elbistan (AE) coal fly ashes obtained by burning coal samples from top, middle and bottom sections of the AE coal seam were characterized and their properties were compared. Chemical analysis of the AE coal fly ashes showed that they are mainly composed of CaO, SiO2, Fe2O3 and Al2O3. Quantitative X-ray diffraction (XRD) analyses were carried out using an interactive data processing system (SIROQUANTTM) based on Rietveld interpretation methods. Lime is found in all the samples, ranging from around 7% to just over 38%. Amorphous contents of fly ashes are ranged between 19% and 25%. Different types of AE fly ashes revealed that bottom section coal fly ash is very similar to Class F, while medium and top section coal fly ashes are close to Class C and they might be used as mineral admixture in concrete. But also they do not comply with any of the standard. The results presented here show new possibilities for AE coal fly ashes in a wide range of fields, resulting in great advantages in waste minimization, as well as, resources conservation

175

Determination of ash content of coal on-line on conveyors and in-stream in coal slurries  

International Nuclear Information System (INIS)

Australian work on the determination of ash content of coal on conveyors, based on the combination of measurements of transmission of low- and high-energy ?-rays, is reviewed. Root mean square differences between gauge and chemical assay are 0.3-0.45 wt% for low-ash coal, and usually 0.7-1.5 wt% for as-mined coal of high ash content. The gauges are in routine use in the Australian coal industry. Techniques have been developed for the determination of the solids weight fraction (W) and ash content of coal in slurries of variable voidage. The technique is based on the correlation between solids weight fraction and hydrogen concentration (wt/wt) of the slurry. The technique combines measurements of neutron moderation, ?-ray transmission, X-ray backscatter and iron K X-ray excitation. In laboratory experiments with coal slurries of 5-20 wt% solids, 21-30 wt% ash, and voidage 0-4 vol.%, RMS differences between gauge and conventional assays were 0.54 wt% solids and 0.78 wt% ash. (author)

176

Coal ash fusion temperatures -- New characterization techniques, and associations with phase equilibria  

Energy Technology Data Exchange (ETDEWEB)

The well-documented shortcomings of the standard technique for estimating the fusion temperature of coal ash are its subjective nature and poor accuracy. Alternative measurements based on the shrinkage and electrical conductivity of heating samples are therefore examined with laboratory ash prepared at about 800 C in crucibles, as well as combustion ash sampled from power stations. Sensitive shrinkage measurements indicate temperatures of rapid change which correspond to the formation of liquid phases that can be identified on ternary phase diagrams. The existence and extent of formation of these phases, as quantified by the magnitude of peaks in the test, provide alternative ash fusion temperatures. The peaks from laboratory ashes and corresponding combustion ashes derived from the same coals show clear differences which may be related to the evaporation of potassium during combustion and the reactions of the mineral residues to form combustion ash.

Wall, T.F.; Gupta, R.P.; Gupta, S. [Univ. of Newcastle, New South Wales (Australia). Dept. of Chemical Engineering; Creelman, R.A. [R.A. Creelman and Associates, Epping, New South Wales (Australia); Coin, C. [ACIRL Ipswich, Booval, Queensland (Australia); Lowe, A. [Pacific Power, Sydney, New South Wales (Australia)

1996-12-31

177

Influence of Chemical Composition on the Electrical Resistivity of Fly Ash Generated from Indian Coal Based Thermal Power Plants  

OpenAIRE

Electrostatic Precipitators (ESP) are control devices widely used for collection of fly ash in Indian coal based thermal power plants. The design, performance, sizing, collection and operation of ESP depend largely on the properties and quality of the coal burned and the fly ash generated in the boilers. This study presents the influence of fly ash composition on the resistivity of Indian fly ash generated from coal based power plants, which is one of the critical parameter required to make a...

Syed Javid Ahmad Andrabi; Avinash Chandra; Mohd Aslam; Hassan, I. A.

2013-01-01

178

Rate limitations of lime dissolution into coal ash slag  

Energy Technology Data Exchange (ETDEWEB)

The rate-limiting mechanisms of lime dissolution from a solid pellet into coal ash slag and synthetic slag was investigated using an experiment involving a rotating cylinder of lime in a liquid slag bath at temperatures of 1450-1650{degree}C. Scanning electron microscopy (SEM) analysis of the slag composition around the lime cylinder was used to determine the nature of the boundary layer surrounding the pellet and the calcium concentration profile. Predictions using shrinking core models of a cylindrical pellet were compared to experimental results, suggesting that diffusion through the slag boundary layer and the change of the phase of lime from solid to liquid in the boundary layer combine to limit the process. These results indicate that a combination of controlling steps: diffusion through the boundary layer and the phase change of lime from solid to liquid, must be considered when predicting lime dissolution rates. 24 refs., 5 figs., 3 tabs.

L.K. Elliott; John A. Lucas; Jim Happ; John Patterson; Harry Hurst; Terry F. Wall [University of Newcastle, Callaghan, NSW (Australia). School of Chemical Engineering

2008-11-15

179

To the method of increasing accuracy of radioisotope analysis of coal ash content  

International Nuclear Information System (INIS)

The method of accuracy increase in radioisotopic analysis of coal ash content, which eliminates destabilizing effect of instability of element composition of coal ash, mainly iron and calcium, is suggested. The method consists in recording not only the dispersed constituent of the spectrum of secondary gamma radiation of iron 55 but in calcium fluorescent radiation (approximately 3.7 keV). Mean quadratic deviation of the method results from the data of chemical analysis constituted 0.32% at Ca amount variation of 2-12% and coal ash content 8-12%

180

Durable power performance of a direct ash-free coal fuel cell  

International Nuclear Information System (INIS)

Highlights: •Investigation of a direct carbon fuel cell (DCFC) using raw and ash-free coal fuels. •Enhanced durability of a DCFC performance using ash-free coal. •Comprehensive characterization of physicochemical properties of coals. •Development of an optimal design of the configuration of DCFC reactor. -- Abstract: We have investigated the comparable performance of raw and ash-free coal in the operation of a direct carbon fuel cell (DCFC). The various structural and morphological analyses using SEM, TEM, EDX, XPS, XRD, and TGA are carried out to study the distinct physicochemical properties of coals. Due to contained volatile organic compounds, raw coal generates about a two-fold higher fuel cell performance compare to ash-free coal below a reaction temperature of 750 °C. However, over a cell temperature of 900 °C, both of them reach a similar power density of 170 mW cm?2. In the long-term operation of a DCFC, we observe a distinctly more durable power performance using ash-free coal than that of raw coal

181

Effects of alkali treatment on ash and sulphur removal from Assam coal  

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The effects of leaching subbituminous coal samples from Boragolai and Ledo collieries of Makum coal field, Assam, India, with aqueous sodium hydroxide solution on removal of ash and sulphur, were investigated. Mild alkali treatment for relatively short period leads to removal of ash from the coal samples. Increase of alkali concentration and treatment time has negative effect on ash reduction due to formation and accumulation of insoluble sodium aluminosilicate. Boragolai coal is less demineralized than Ledo coal and is attributed to presence of higher amount of alkali-soluble silica and alumina. Alkali treatment leads to over 70% removal of the inorganic sulphur in the coal samples. Desulphurization increases with increase in alkali concentration and treatment time.

Mukherjee, Samit; Borthakur, P.C. [Material Science Division, Regional Research Laboratory (CSIR), Jorhat-785006, Assam (India)

2003-02-15

182

Trace and major element pollution originating from coal ash suspension and transport processes  

Energy Technology Data Exchange (ETDEWEB)

Coal ash obtained from Nikola Tesla A power plant in Obrenovac, near Belgrade, Yugoslavia, is mixed with water of the Sava river and transported to the dump. In order to assess pollution caused by leaching of some minor and major elements during ash transport through the pipeline, two sets of samples (six samples each) were subjected to a modified sequential extraction. The first set consisted of coal ash samples taken immediately after combustion, while the second set was obtained by extraction with river water, imitating the processes that occur in the pipeline. Samples were extracted consecutively with distilled water and a 1 M solution of KCl, pH 7, and the differences in extractability were compared in order to predict potential pollution. It is concluded that lead and cadmium do not present an environmental threat during and immediately after ash transport to the dump. Portions of zinc, nickel and chromium are released during the ash transport, and arsenic and manganese are released continuously. Copper and iron do not present an environmental threat due to element leaching during and immediately after the coal ash suspension and transport. On the contrary, these elements, as well as chromium, become concentrated during coal ash transport. Adsorbed portions of calcium, magnesium and potassium are also leached during coal ash transport.

Popovic, A.; Djordjevic, D.; Polic, P. [University of Belgrade, Belgrade (Yugoslavia). Faculty of Science, Dept. of Chemistry

2001-07-01

183

Relations between ash-fusion characteristics and depositional environment for an Appalachian Basin coal seam  

International Nuclear Information System (INIS)

This paper reports that ash-fusion characteristics of the Lower Kittanning seam (western Pennsylvania) can be related to environment of deposition. Non-slagging coals (coals with ashes that have ash-fusion temperatures [AFTs] in excess of 2,600 degrees F) are associated with fresh-water environments that occur toward the margins of the basin. Slagging coals (coals with ashes that melt at temperatures less than 2,000 degrees F) occur in the central part of the basin, in areas overlain by shales that have been interpreted to have formed in a brackish environment. Trend-surface analysis indicates that whereas strong basinal trends do exist, locally variability can modify regional trends. High ash-fusion coals are associated with high clay (primarily kaolinite) contents, whereas low-fusion coals are associated with high pyrite and marcasite (and to a lesser extent, siderite) contents. Bivariate analysis of these data shows highly significant negative correlations between AFT and Fe2O3, pyrite, and siderite. Positive correlations exist between AFT and SiO2, Al2O3, TiO2, MgO, and K2O. Illite and kaolinite also correlate positively with AFT. An understanding of the oxide and mineral composition of the ash and the depositional environment of the peat can therefore be useful in the prediction of ash-fusion characteristics

184

Mercury in coal ash and its fate in the Indian subcontinent: A synoptic review  

International Nuclear Information System (INIS)

In the Indian subcontinent power generation is mainly dependent upon the thermal power units and coal is burnt as a fuel for the production of heat and electricity. In India, bituminous and sub-bituminous coals are used which contain over 40% of ash. At present, 80-90 million tons of fly ashes are generated from 85 existing coal based thermal power plants. Coal contains trace metals of which mercury is most toxic for humans and aquatic fauna. The problem of mercury in the society is not new, but in recent years the Indian subcontinent has gained the reputation of being 'a dumping ground for mercury'. This study focuses on mercury in fly ash and its releases to the atmosphere and soils cross the country. The utilisation of coal ash in India is also addressed although it is still in its nascent stage. About 10% of produced fly ashes are used in India whereas in Western countries its use is typically over 70%. Regulations from India's Ministry of Environment and Forestry should increase coal fly ash utilisation, although this would require that cost-effective new technology is put to use. As to the release of Hg from ashes disposed of in the environment, the scarce literature suggests that this is negligible or zero, and less problematic than wet or dry deposition of Hg from flue gases. (author)

185

Reduction of metal leaching in brown coal fly ash using geopolymers  

International Nuclear Information System (INIS)

Current regulations classify fly ash as a prescribed waste and prohibit its disposal in regular landfill. Treatment of the fly ash can reduce the leach rate of metals, and allow it to be disposed in less prescribed landfill. A geopolymer matrix was investigated as a potential stabilisation method for brown coal fly ash. Precipitator fly ash was obtained from electrostatic precipitators and leached fly ash was collected from ash disposal ponds, and leaching tests were conducted on both types of geopolymer stabilised fly ashes. The ratio of fly ash to geopolymer was varied to determine the effects of different compositions on leaching rates. Fourteen metals and heavy metals were targeted during the leaching tests and the results indicate that a geopolymer is effective at reducing the leach rates of many metals from the fly ash, such as calcium, arsenic, selenium, strontium and barium. The major element leachate concentrations obtained from leached fly ash were in general lower than that of precipitator fly ash. Conversely, heavy metal leachate concentrations were lower in precipitator fly ash than leached pond fly ash. The maximum addition of fly ash to this geopolymer was found to be 60 wt% for fly ash obtained from the electrostatic precipitators and 70 wt% for fly ash obtained from ash disposal ponds. The formation of geopolymer in the presence of fly ash was studied using 29Si MAS-NMR and showed that a geopolymer matrix was formed. X-ray diffraction (XRD) analysis aformed. X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) imaging showed the interaction of the fly ash with the geopolymer, which was related to the leachate data and also the maximum percentage fly ash addition

186

Elemental characterization of coal ash and its leachates using sequential extraction techniques  

International Nuclear Information System (INIS)

Over 50 million tons of coal ash are produced annually in North America. Technological improvements in air pollution control have decreased stack emissions but have also increased contaminant concentrations in the ash of coal-fired boiler applications. The leaching of heavy metals and other elements during regulatory tests may cause coal ash to be classified as hazardous waste, complicating land disposal. The hazardous nature of coal ash remains unclear because current toxicity tests fail to effectively characterize the elemental distribution and chemical solubility of trace metals in the landfill environment. Leaching characteristics of ash samples can be investigated with various laboratory extraction procedures in association with multi-elemental analytical techniques (e.g., neutron activation analysis and inductively coupled plasma - atomic emission spectroscopy). Such methods provide more thorough analyses of coal ash leaching dynamics than the regulatory assessments can demonstrate. Regulatory elements including Ag, As, Ba, Cd, Cr, Hg, Pb, and Se were shown to remain in largely insoluble forms while elements such as B and S leached at higher levels. Experimental results may assist operators of coal-fired boiler industries in selecting coal types and disposal options to curtail the leaching of potentially toxic inorganic contaminants. (author) 12 refs.; 4 figs.; 3 tabs

187

Unsubstituted polyaromatic hydrocarbons (PAH's) in extracts of coal fly ash from the fly ash test cell in Montour, Pennsylvania  

International Nuclear Information System (INIS)

Isotope Dilution Mass Spectrometry (IDMS) was used to identify and to quantify trace amounts of selected, unsubstituted polyaromatic hydrocarbons (PAH's) present in extracts of coal fly ash from the solid waste disposal test cell at Montour, Pennsylvania. Isotope dilution experiments using deuterated analogs of polyaromatic hydrocarbons demonstrated that the concentrations of benzo[a]pyrene and anthracene were lower than 1 ng/g of fly ash. Isotope dilution experiments demonstrated that benzo[a]pyrene could be detected at concentrations as high as 1 ng/g when an isotopic carrier was used at a concentration of 125 ng/g in the analytical method. Maximum concentrations of fluorene, fluoranthene, pyrene and chrysene were conservatively estimated to be 3 ng/g of fly ash, using a 95 percent confidence interval based on analytical precision of ±1 ng/g of fly ash. Concentrations of phenanthrene were found to range from 6 to 38 ng/g of fly ash with a mean concentration of 14 ng/g of fly ash. Two sources of phenanthrene were speculated: incomplete combustion of phenanthrene in the coal furnace and addition of phenanthrene to the fly ash after collection by electrostatic precipitators

188

A backscatter gamma-ray spectrometric method for the determination of ash in coal  

International Nuclear Information System (INIS)

The method described is based on gamma-ray backscattering and utilizes the energy dependence of the backscattered gamma-ray peak. In the present work, a pair of windows established on either side of the backscattered gamma-ray peak were used to determine the apparent position of the peak which was strongly correlated with ash content. This technique requires only a four-channel spectrometer system. Laboratory tests carried out on 30 coal samples, with a wide range of ash composition, showed that ash content could be determined with a standard deviation of 1.5% ash for ash contents between 7 and 58%. (orig.)

189

Bioavailability of 1-nitropyrene from model coal fly ash and its uptake by alveolar macrophages  

Energy Technology Data Exchange (ETDEWEB)

Alveolar macrophage cultures exposed to coal fly ash vapor-coated with 1-nitropyrene were used as a model system to study the bioavailability and the uptake of a nitroaromatic hydrocarbon from coal combustion emissions. Initially, 1-nitropyrene-coated fly ash and uncoated fly ash were examined for cytotoxicity using rabbit alveolar macrophages and for mutagenicity in the Salmonella typhimurium plate incorporation assay. The distribution and recovery of 1-nitropyrene from macrophage cultures treated with coated fly ash were determined by using a reverse-hase high-performance liquid chromatography-fluorescence method. 1-Nitropyrene alone was not very toxic, nor did vapor deposition of 1-nitropyrene onto coal fly ash significantly affect the toxicity of the fly ash. Most toxicity resulted from the original, uncoated fly ash particles. 1-Nitropyren after being coated onto the particles was bioavailable in agar and aqueous culture medium. The coated fly ash showed mutagenic activity when the particles were tested directly; the uncoated fly ash did not show mutagenic activity. 1-Nitropyrene recovery from alveolar macrophage cultures exposed to the coated fly ash diminished as cell number increased. The rate of 1-nitropyrene loss was 2.7 ng/10/sup 6/ macrophages for medium and 4.1 ng/10/sup 6/ macrophages for the whole culture. The mutagenic activity recovered from these macrophage cultures also decreased with increasing cell number.

Mumford, J.L.; Tedjad, S.B.; Jackson, M.; Lewtas, J.

1986-08-01

190

Bioavailability of 1-nitropyrene from model coal fly ash and its uptake by alveolar macrophages  

Energy Technology Data Exchange (ETDEWEB)

Alveolar macrophage cultures exposed to coal fly ash vapor-coated with 1-nitropyrene were used as a model system to study the bioavailability and the uptake of a nitroaromatic hydrocarbon from coal-combustion emissions. Initially, 1-nitropyrene-coated fly ash and uncoated fly ash were examined for cytotoxicity using rabbit alveolar macrophages and for mutagenicity in the Salmonella typhimurium plate incorporation assay. The results were compared to determine the effects of vapor deposition. The distribution and recovery of 1-nitropyrene from macrophage cultures treated with coated fly ash were determined by using a reverse-phase high-performance liquid chromatography-fluorescence method. 1-Nitropyrene alone was not very toxic, nor did vapor deposition of 1-nitropyrene onto coal fly ash significantly affect the toxicity of the fly ash. Most toxicity resulted from the original, uncoated, fly ash particles, 1-Nitropyrene after being coated onto the particles was bioavailable in agar and aqueous culture medium. The coated fly ash showed mutagenic activity when the particles were tested directly; the uncoated fly ash did not show mutagenic activity. 1-Nitropyrene recovery from alveolar macrophage cultures exposed to the coated fly ash diminished as cell number increased. The rate of 1-nitropyrene loss was 2.7 ng/.000001 macrophages for medium and 4.1 ng/.000001 macrophages for the whole culture. The mutagenic activity recovered from these macrophage cultures also decreased with increasing cell number.

Mumford, J.L.; Tejada, S.B.; Jackson, M.; Lewtas, J.

1986-01-01

191

Sampling and analysis of groundwater at coal ash management sites  

International Nuclear Information System (INIS)

The utility industry, through the Electric Power Research Institute (EPRI), is developing techniques to evaluate the potential migration of waste constituents from utility disposal sites. This paper highlights approaches and methods for monitoring the migration of inorganic constituents in groundwater away from an ash disposal pond. The approach will also apply to other disposed wastes and waste sites. A comprehensive groundwater monitoring program includes several distinct tasks, including site reconnaissance, sampling design, sample collection, analysis, data management, data presentation, and quality assurance. A recent manual published by EPRI, entitled Techniques to Develop Data for Hydrogeochemical Models, addresses most aspects of a disposal site monitoring program. This paper summarizes the particular approaches and methods evaluated for collecting, preserving, and analyzing samples, and for presenting groundwater monitoring data gathered at fossil fuel waste disposal sites. Preliminary results are presented from a case study at an ash pond site. Several methods are available for collecting groundwater samples. The most appropriate techniques withdraw water from wells at nearly ambient pressures with minimum atmospheric exposure. Suitable devices include a peristaltic pump (for depths less than 5 meters), a bladder pump, or a bailer equipped for in-line filtration. Several unstable analytes are measured at the wellhead, including temperature, pH, Eh, alkalinit, including temperature, pH, Eh, alkalinity, dissolved oxygen, and specific conductance. Samples are preserved for laboratory analysis of other constituents. Methods are evaluated and recommended for analysis of major and trace elements, anionic species, and inorganic and organic carbon. Data analysis and presentation are important both to convey information needed for decision making and to formulate conceptual models of the site. Options presented in this paper include isoconcentration contouring and statistical evaluation methods

192

Mercury capture by selected Bulgarian fly ashes: Influence of coal rank and fly ash carbon pore structure on capture efficiency  

Science.gov (United States)

Mercury capture by fly ash C was investigated at five lignite- and subbituminous-coal-burning Bulgarian power plants (Republika, Bobov Dol, Maritza East 2, Maritza East 3, and Sliven). Although the C content of the ashes is low, never exceeding 1.6%, the Hg capture on a unit C basis demonstrates that the low-rank-coal-derived fly ash carbons are more efficient in capturing Hg than fly ash carbons from bituminous-fired power plants. While some low-C and low-Hg fly ashes do not reveal any trends of Hg versus C, the 2nd and, in particular, the 3rd electrostatic precipitator (ESP) rows at the Republika power plant do have sufficient fly ash C range and experience flue gas sufficiently cool to capture measurable amounts of Hg. The Republika 3rd ESP row exhibits an increase in Hg with increasing C, as observed in other power plants, for example, in Kentucky power plants burning Appalachian-sourced bituminous coals. Mercury/C decreases with an increase in fly ash C, suggesting that some of the C is isolated from the flue gas stream and does not contribute to Hg capture. Mercury capture increases with an increase in Brunauer-Emmett-Teller (BET) surface area and micropore surface area. The differences in Hg capture between the Bulgarian plants burning low-rank coal and high volatile bituminous-fed Kentucky power plants suggests that the variations in C forms resulting from the combustion of the different ranks also influence the efficiency of Hg capture. ?? 2010 Elsevier Ltd.

Kostova, I.J.; Hower, J.C.; Mastalerz, M.; Vassilev, S.V.

2011-01-01

193

Magnetic susceptibility measurements to detect coal fly ash from the Kingston Tennessee spill in Watts Bar Reservoir  

International Nuclear Information System (INIS)

An estimated 229 000 m3 of coal fly ash remains in the river system after dredging to clean-up the 2008 Tennessee Valley Authority (TVA) spill in Kingston, Tennessee. The ash is heterogeneous with clear, orange and black spheres and non-spherical amorphous particles. Combustion produces iron oxides that allow low field magnetic susceptibility (?LF) and percent frequency dependent susceptibility (?FD%) to be used to discriminate between coal fly ash and sediments native to the watershed. Riverbed samples with ?LF greater than 3.0 × 10?6 m3/kg, have greater than 15% ash measured by optical point counting. ?LF is positively correlated with total ash, allowing ash detection in riverbed sediments and at depth in cores. The ratio of ash sphere composition is altered by river transport introducing variability in ?LF. Measurement of ?LF is inexpensive, non-destructive, and a reliable analytical tool for monitoring the fate of coal ash in this fluvial environment. -- Highlights: ? Coal fly ash is composed of spheres (clear, orange, black) and amorphous particles. ? Black spheres dominate the magnetic susceptibility signal (?LF). ? The river sorts ash but maintains a ratio of clear: orange: black ash. ? ?LF measurements can predict % ash spheres from simple linear regression. ? ?LF can be used to track coal ash in the riverbed and in sediment cores. -- An application of magnetic susceptibility for tracking the distribution of coal fly ash within a river system after the 2008 TVA spill at Kingston, Tennessee

194

Activation analysis of pit-coal ash content with the use of isotopic fast neutron source  

International Nuclear Information System (INIS)

The neutron activation techniques of coal ash determination are briefly reviewed and a new version of activation analysis using fast neutrons from 239Pu-Be source and basing on the reactions 28Si(n,p)28Al and 27Al(n,p)27Mg is proposed. 72 samples of pit-coals with ash content ranging from 3 to 40% were measured. The linear calibration function between ash content and both, 1.78 MeV and 0.84 MeV, ?-ray counts was obtained. The precision (0.94% ash for 17% ash content) and accuracy (1.4%ash for the whole range) were evaluated. Comparison of the results with those of fluorescent-scattering methods is made. (author)

195

Hyperfine and X-ray studies of coal and coal ash  

International Nuclear Information System (INIS)

X-ray diffraction and 57Fe Moessbauer hyperfine studies have been made to characterize the iron-bearing minerals present in some of the Indian coals. The minerals observed in a range of samples by Moessbauer study include siderite (FeCO3) and Fe3+, Fe2+-bearing silicate clay minerals such as illite. X-ray analysis also showed the diffraction lines of siderite and illite along with non-iron phases like quartz and calcium oxide. The effects of ashing (at 750deg C) were also studied by Moessbauer spectroscopy. (orig.)

196

Cobalt(II) removal from synthetic wastewater by adsorption on South African coal fly ash  

OpenAIRE

Advanced wastewater-treatment techniques such as adsorption are essential in the removal of non- biodegradable toxic wastes from water. In this study, the use of South African coal fly ash, an industrial byproduct, has been investigated as a potential replacement for the current costly adsorbents used for removing heavy metals from wastewater. We utilised coal fly ash for the adsorption of cobalt(II) ions from synthetic petrochemical wastewater and characterised its performance. A two-level t...

Ochieng Aoyi; Onyango, Maurice S.; Musapatika, Evans T.

2010-01-01

197

Spectrophotometric determination of phosphorus in coal and coal ash using bismuth-phosphomolybdate complex  

Directory of Open Access Journals (Sweden)

Full Text Available A modified spectrophotometric method using the bismuth phosphomolybdate complex for the determination of phosphorus in coal and coal ash is suggested. Bismuth together with phosphate and molybdate forms a very stable complex in acid medium which turns blue (?molibdenum blue? by reduction with ascorbic acid. The apparent molar absorptivity of PBiMo is 1.66x104 dm3 mol-1cm-1 at 720 nm and 2.10x104 dm3 mol-1cm-1 at 670 nm isobutyl methyl ketone (MIBK. Interference caused by the ions present are within the tolerance limits (±2 %. Beer?s law is obeyed in the for concentration range to 0.6 mg/mL (aqueous solution and to 1.2 mg/mL P (MIBK. The sesitivity of the proposed method is 0.0078 mg/mL (aqueous solution and 0.0066 mg/mL (MIBK.

VESNA M. KALJEVIC

2003-01-01

198

EFFECT OF ASH DISPOSAL PONDS ON GROUNDWATER QUALITY AT A COAL-FIRED POWER PLANT  

Science.gov (United States)

The impact of fly and bottom ash disposal ponds on groundwater quality was investigated at the coal-fired Columbia Power Plant at Portage, WI. Groundwater sampling was conducted utilizing a network of piezometers and multilevel wells located at various cross-sections of the ash d...

199

Radiological impact of coal ash from the power plants in Hong Kong  

International Nuclear Information System (INIS)

Samples of coal, furnace bottom ash and pulverised fly ash were collected from the two electric companies in Hong Kong. The samples were collected over a period of 1 year and therefore they were representative of the annual consumption of coal as well as the annual production of the ash. Special procedures were taken to separately burn the coal bought from different places so that the origins of the ash samples are traceable. The radionuclide contents, radon emanating fraction and porosity of the samples were measured. Mathematical models were then used to evaluate the radiological hazard of the ash samples when used in the building industry. Both the ? and radon exposures due to the coal ash loaded concrete in buildings are not much different from that due to unloaded concrete. External ? dose rate and 222Rn concentration at the centre of an uncovered ash lagoon are estimated to be 0.165 ?Gy h-1 and 2.9 Bq m-3, respectively, again not much different from the local background. On the other hand, the committed effective dose due to inhalation of PFA of about 7.1 x 108 B ?S?, where B is the PFA loading in air, can be an important source of exposure if resuspension of ash particles is not properly controlled. (author)

200

Effect of coal ash on growth and metal uptake by some selected ectomycorrhizal fungi in vitro  

Energy Technology Data Exchange (ETDEWEB)

Six isolates of ectomycorrhizal fungi namely, Laccaria fraterna (EM-1083), Pisolithus tinctorius (EM-1081), Pisolithus tinctorius (EM-1290), Pisolithus tinctorius (EM-1293), Scleroderma verucosurn (EM-1283), and Scleroderma cepa (EM-1233), were grown on three variants of coal ash, namely electrostatically precipitated (ESP) ash, pond ash, and bottom ash moistened with Modified Melin-Norkans (MMN) medium in vitro. The colony diameter reflected the growth of the isolates on the coal ash. Metal accumulation in the mycelia was assayed by atomic absorption spectrophotometry. Six metals, namely aluminum, cadmium, chromium, iron, lead, and nickel were selected on the basis of their abundance in coal ash and toxicity potential for the present work. Growth of vegetative mycelium on fly ash variants and metal accumulation data indicated that Pisolithus tinctorius (EM-1290) was the most tolerant among the isolates tested for most of the metals. Since this isolate is known to be mycorrhizal with Eucalyptus, it could be used for the reclamation of coal ash over burdened sites.

Ray, P.; Reddy, U.G.; Lapeyrie, F.; Adholeya, A. [Energy & Resources Institute, New Delhi (India)

2005-07-01

201

Effect of coal ash on growth and metal uptake by some selected ectomycorrhizal fungi in vitro.  

Science.gov (United States)

Six isolates of ectomycorrhizal fungi namely, Laccaria fraterna (EM-1083), Pisolithus tinctorius (EM-1081), Pisolithus tinctorius (EM-1290), Pisolithus tinctorius (EM-1293), Scleroderma verucosum (EM-1283), and Scleroderma cepa (EM-1233), were grown on three variants of coal ash, namely electrostatically precipitated (ESP) ash, pond ash, and bottom ash moistened with Modified Melin-Norkans (MMN) medium in vitro The colony diameter reflected the growth of the isolates on the coal ash. Metal accumulation in the mycelia was assayed by atomic absorption spectrophotometry. Six metals, namely aluminum, cadmium, chromium, iron, lead, and nickel, were selected on the basis of their abundance in coal ash and toxicity potential for the present work. Growth of vegetative mycelium on fly ash variants and metal accumulation data indicated that Pisolithus tinctorius (EM-1290) was the most tolerant among the isolates tested for most of the metals. Since this isolate is known to be mycorrhizal with Eucalyptus, it could be used for the reclamation of coal ash over burdened sites. PMID:16285411

Ray, Prasun; Reddy, U Gangi; Lapeyrie, Frederic; Adholeya, Alok

2005-01-01

202

Task 5.9 - use of coal ash in recycled plastics and composite materials  

Energy Technology Data Exchange (ETDEWEB)

The goal of this research project by the Energy & Environmental Research Center (EERC) was to determine the potential for coal ash to serve as a {open_quote}functional filler{close_quotes} in plastics and other composite materials, with special emphasis on recycled plastics. The term functional filler is intended to indicate that the material added to the plastic does more than take up space and extend the use of the polymer. Determining the functional filler potential of ash was not the only intent of this project, since another prime objective was to find a use for materials currently considered waste. The term functional filler also opened a door to the use of cenospheres, which are currently marketed and for which there is sufficient market demand that they do not fit the category of a waste even though they are a product of coal combustion. Cenospheres, hollow spherical ash particles, were selected because of their unique properties. Although they currently have commercial applications, the unique nature of these materials make them an excellent candidate for use as a functional filler in composites. The ability to produce a commercially viable product from waste streams and a recycled material is a positive step toward reducing solid waste. The first task, since there are numerous types of coal ash, was to select suitable ash types for use in this project. Three basic types of material were selected: fly ash, a bottom ash, and a unique form of coal ash known as cenospheres.

Hassett, D.J.; Dockter, B.A.; Eylands, K.E.; Pflughoeft-Hassett, D.F.

1995-07-01

203

Task 5.9 use of coal ash in recycled plastics and composite materials. Topical report  

Energy Technology Data Exchange (ETDEWEB)

The goal of this research project by the Energy & Environmental Research Center (EERC) was to determine the potential for coal ash to serve as a {open_quotes}functional filler{close_quotes} in plastics and other composite materials, with special emphasis on recycled plastics. The term functional filler is intended to indicate that the material added to the plastic does more than take up space and extend the use of the polymer. Determining the functional filler potential of ash was not the only intent of this project, since another prime objective was to find a use for materials currently considered waste. The term functional filler also opened a door to the use of cenospheres, which are currently marketed and for which there is sufficient market demand that they do not fit the category of a waste even though they are a product of coal combustion. Cenospheres, hollow spherical ash particles, were selected because of their unique properties. Although they currently have commercial applications, the unique nature of these materials make them an excellent candidate for use as a functional filler in composites. The ability to produce a commercially viable product from waste streams and a recycled material is a positive step toward reducing solid waste. The first task, since there are numerous types of coal ash, was to select suitable ash types for use in this project. Three basic types of material were selected: fly ash, a bottom ash, and a unique form of coal ash known as cenospheres.

Hassett, D.J.; Dockter, B.A.; Eylands, K.E.; Pflughoeft-Hassett, D.F.

1995-11-01

204

Deposition and retention of neutron-activated pulverized coal combustor fly ash inhaled by Beagle dogs  

International Nuclear Information System (INIS)

Beagle dogs were exposed by inhalation to an aerosol of neutron-activated fly ash from a pulverized coal combustor. The radionuclide content of whole body, tissue and excreta is being analyzed to define the fate of the neutron-activated fly ash and its constituents after inhalation exposure. Preliminary results are presented for whole body biological retention of 59Fe and 46Sc, two neutron activation products of the fly ash

205

Predicting coal ash fusion temperature based on its chemical composition using ACO-BP neural network  

International Nuclear Information System (INIS)

Coal ash fusion temperature is important to boiler designers and operators of power plants. Fusion temperature is determined by the chemical composition of coal ash, however, their relationships are not precisely known. A novel neural network, ACO-BP neural network, is used to model coal ash fusion temperature based on its chemical composition. Ant colony optimization (ACO) is an ecological system algorithm, which draws its inspiration from the foraging behavior of real ants. A three-layer network is designed with 10 hidden nodes. The oxide contents consist of the inputs of the network and the fusion temperature is the output. Data on 80 typical Chinese coal ash samples were used for training and testing. Results show that ACO-BP neural network can obtain better performance compared with empirical formulas and BP neural network. The well-trained neural network can be used as a useful tool to predict coal ash fusion temperature according to the oxide contents of the coal ash

206

Predicting coal ash fusion temperature based on its chemical composition using ACO-BP neural network  

Energy Technology Data Exchange (ETDEWEB)

Coal ash fusion temperature is important to boiler designers and operators of power plants. Fusion temperature is determined by the chemical composition of coal ash, however, their relationships are not precisely known. A novel neural network, ACO-BP neural network, is used to model coal ash fusion temperature based on its chemical composition. Ant colony optimization (ACO) is an ecological system algorithm, which draws its inspiration from the foraging behavior of real ants. A three-layer network is designed with 10 hidden nodes. The oxide contents consist of the inputs of the network and the fusion temperature is the output. Data on 80 typical Chinese coal ash samples were used for training and testing. Results show that ACO-BP neural network can obtain better performance compared with empirical formulas and BP neural network. The well-trained neural network can be used as a useful tool to predict coal ash fusion temperature according to the oxide contents of the coal ash. (author)

Liu, Y.P.; Wu, M.G.; Qian, J.X. [Institute of Industrial Control Technology, College of Info Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

2007-02-15

207

Development of bricks with incorporation of coal ash and sludge from water treatment plant  

International Nuclear Information System (INIS)

Sludge from treatment water Brazilian plant station are, frequently, disposed and launched directly in the water bodies, causing a negative impact in the environment. Also, coal ashes is produced by burning of coal in coal-fired power stations and is the industrial solid waste most generated in southern Brazil: approximately 4 million tons/y. The efficient disposal of coal ashes is an issue due to its massive volume and harmful risks to the environment. The aim of this work was study the feasibility of incorporating these two industrial wastes in a mass used in the manufacture of ecological bricks. Samples of fly ashes from a cyclone filter from a coal-fired power plant located at Figueira County in Parana State, Brazil and waterworks sludge of Terra Preta County in Sao Paulo State, Brazil, were used in the study. Fly ash-sludge and fly ash-sludge-soil-cement bricks were molded and tested, according to the Brazilians Standards. The materials were characterized by physical-chemical analysis, X-ray diffraction, thermal analysis, morphological analysis, Fourier transform infrared spectroscopy and granulometric analysis. The results indicate that the waterworks sludge and coal ashes have potential to be used on manufacturing soil-cement pressed bricks according to the of Brazilians Standards NBR 10836/94. (author)

208

Coal fly ash disposal in the ocean: an alternative worth considering  

Energy Technology Data Exchange (ETDEWEB)

Chemical and biological experiments measured the solubility of 16 elements in coal fly ash and the short-term toxicity of coal fly ash to clams and phytoplankton. Of the elements studied, 10 to 60% of the As, Br, Cr, Sb, Se, Ni, Pb, and Sr dissolved within a 24-hour period. Elements which were less than 10% soluble in 24-hours included Cu, Zn, Na, La, Sc, Fe, Co and Eu. Littleneck clams (Protothaca staminea) were exposed to coal fly ash in flowing seawater for a 25-day period. At the end of the exposure Cu concentration in gills was 15 ..mu..g g/sup -1/ dry wt compared to 6 ..mu..g g/sup -1/ in control clams. Elements that were not elevated in the exposed clams were Mn, Fe, Ni, Zn, Se and As. The effects of the soluble fraction of coal fly ash on primary production was measured by /sup 14/C uptake rate on coastal phytoplankton. The addition of soluble coal fly ash material had no effect on the /sup 14/C uptake rate of phytoplankton. These measurements were made in the productive Washington shelf water during August. The literature indicates coal fly ash has a relatively low toxicity to plants and animals. Disposal methods could be designed so EPA water quality criteria levels would not be exceeded except in the immediate vicinity of the dumpsite.

Crecelius, E.A.

1981-10-01

209

Physico-chemical characterization of water extracts of different coal fly ashes and fly ash-amended composts  

Energy Technology Data Exchange (ETDEWEB)

The pH, conductivity and the concentration of 15 selected elements were measured in the water extracts of five coal fly ash samples collected from Savannah River Site (SRS) and one from South Carolina Electric and Gas (SCE G) power plant. This work was intended to study the differences in the physico-chemical properties of SRS fly ash samples relative to those of a reference sample (SCE G) and to make fly ash-amended composts for agricultural use. Similar analyses were also performed in water extracts of commercial organic manure, 'Gotta Grow', that was composted with one of the fly ash samples (SRS 484-D) in different proportions. Our results show that fly ash samples used in this study differ considerably in pH, conductivity, and elemental composition and that transition metals appear to bind more tightly on smaller particles than on larger ones. The elementally rich manure, 'Gotta Grow', is not suitable to study the effects of fly ash on the elemental release from fly ash-amended composts. Low grade or home-made organic composts are being investigated as possible choice for making fly ash-amended composts. 13 refs., 4 figs., 5 tabs.

Menon, M.P.; Ghuman, G.S.; James, J.; Chandra, K.; Adriano, D.C. (Savannah State College, Savannah, GA (USA). School of Sciences and Technology)

1990-03-01

210

Ash bed level control system for a fixed-bed coal gasifier  

Science.gov (United States)

An ash level control system is provided which incorporates an ash level meter to automatically control the ash bed level of a coal gasifier at a selected level. The ash level signal from the ash level meter is updated during each cycle that a bed stirrer travels up and down through the extent of the ash bed level. The ash level signal is derived from temperature measurements made by thermocouples carried by the stirrer as it passes through the ash bed and into the fire zone immediately above the ash bed. The level signal is compared with selected threshold level signal to determine if the ash level is above or below the selected level once each stirrer cycle. A first counter is either incremented or decremented accordingly. The registered count of the first counter is preset in a down counter once each cycle and the preset count is counted down at a selected clock rate. A grate drive is activated to rotate a grate assembly supporting the ash bed for a period equal to the count down period to maintain the selected ash bed level. In order to avoid grate binding, the controller provides a short base operating duration time each stirrer cycle. If the ash bed level drops below a selected low level or exceeds a selected high level, means are provided to notify the operator.

Fasching, George E. (Morgantown, WV); Rotunda, John R. (Fairmont, WV)

1984-01-01

211

ANALYSIS OF FLY ASH PRODUCED FROM COMBUSTION OF REFUSE-DERIVED FUEL AND COAL MIXTURES (JOURNAL VERSION)  

Science.gov (United States)

Mixtures of coal and refuse-derived fuel (RDF) were burned and the fly ash was collected and analyzed for concentration trends with respect to RDF/coal ratio and particle size. RDF contributes more Cs, Mn, Sb, and Pb to the fly ash while coal contributes greater amounts of As, Br...

212

Coal ash fusion temperatures - new characterization techniques and implications for slagging and fouling  

Energy Technology Data Exchange (ETDEWEB)

The ash fusion test (AFT) is the accepted test for the propensity of coal ash to slag in the furnace. The well-documented shortcomings of this technique for estimating the fusion temperature of coal ash are its subjective nature and poor accuracy. Alternative measurements based on the shrinkage and electrical conductivity of heating samples are therefore examined here with laboratory ash prepared at about 800{degree}C in crucibles, as well as combustion ash samples from power stations. Sensitive shrinkage measurements indicate temperatures of rapid change which correspond to the formation of liquid phases that can be identified on ternary phase diagrams. The existence and extent of formation of these phases, as quantified by the magnitude of `peaks` in the test, provide alternative ash fusion temperatures. The peaks from laboratory ashes and corresponding combustion ashes derived from the same coals show clear differences which may be related to the evaporation of potassium during combustion and the reactions of the mineral residues to form combustion ash. A preliminary evaluation of data from nine power stations indicates that shrinkage measurements can provide an alternative approach to characterizing slagging. 15 refs., 9 figs., 2 tabs.

Wall, T.F.; Creelman, R.A.; Gupta, R.P.; Gupta, S.K.; Coin, C.; Lowe, A. [University of Newcastle, Newcastle, NSW (Australia). CRC for Black Coal Utilisation

1998-09-01

213

Coal ash transportation as paste-like, highly loaded pulps in Brazil: characterization and main features  

Energy Technology Data Exchange (ETDEWEB)

The transportation of mineral coal ash in trucks with open top load compartments is inefficient, harmful to the environment, and costly. One solution to this problem is to utilize highly concentrated aqueous suspensions (paste) transportation systems, through steel pipes assisted by hydraulic pumping. In this study, coal ash (both fly ash and bottom ash), produced at a typical coal power plant (South Brazil), was utilized at different formulations, with mixtures of fly ash, bottom ash, and water (65%-70% solids content). These ash-bearing pulps were characterized in terms of their chemical and mineralogical composition, suspension pH that varied with the presence of Ca-bearing minerals, particle size distribution, and rheological behavior. Ash samples were distributed in fine, mean, and coarse sizes, facilitating the particles packing, diminishing voids, and contributing to the formation of paste with good consistency. The ash suspensions (32% water content) did not show compression strength and were plastically deformed after 48 hours of water addition. This behavior indicates that there were no chemical reactions, or pozzolanic activity, and that the particle interactions were mainly due to electrostatic forces and dispersions forces.

Braganca, S.R.; Goncalves, M.R.F.; Bergmann, C.P.; Rubio, J. [Universidade Federal do Rio Grande do Sul, Porto Alegre (Brazil)

2009-07-01

214

Evaluation of the ecological risks to terrestrial wildlife associated with a coal ash disposal site  

International Nuclear Information System (INIS)

Between 1955 and 1989, coal ash was deposited within an impounded watershed on the Oak Ridge Reservation, creating the 3.6 ha-Filled Coal Ash Pond (FCAP). The site has subsequently become vegetated, providing habitat for wildlife. To evaluate the risks that metals in the ash may pose to wildlife, ash, surface water, small mammal, and vegetation samples were collected and metal residues were determined. Metal concentrations, As and Se in particular, were elevated in ash, surface water, plant foliage, and small mammals relative to reference materials. Estimates of metal exposures received from food, water, and ash consumption were calculated for short-tailed shrews, white-footed mice, white-tailed deer, red fox, and red-tailed hawks. While shrews and mice were assumed to reside exclusively at and receive 100% exposure from the site, exposure experienced by deer, fox, and hawks was assumed to be proportional to the size of the site relative to their home range. Because deer had been observed to consume ash presumably for it's high sodium content, exposure experienced by deer consuming ash to meet sodium requirements was also estimated. To assess the risk of coal ash to wildlife, exposure estimates were compared to body-size adjusted toxicity data for each metal. These comparisons suggest that metals at the site may be detrimental to reproduction and survivorship of mice, shrews, deer and fox; hawks do not appear to be at risk

215

Surface studies of coal, oil, and coal-oil-mixture ash using auger electron spectroscopy and solvent leaching techniques  

International Nuclear Information System (INIS)

Fly ash produced by the combustion of coal, oil, and a coal-oil mixture have been studied by Auger electron spectroscopy and solvent leaching techniques. The Auger data indicate that the surface concentration of the metal ions Na, Fe, Mg, Ni, V, and Al as well as S and C increases on going from coal to coal-oil mixture and oil ash. The relative surface enrichments of oil and coal-oil-mixture ash are consistent with a simple model of the ash-formation process, and the results confirm that several toxic metals are significantly enriched on the surface of the ash particles. The Auger data are compared to HCl and tris buffer leachate composition analyses, and in neither case does the leachate give an accurate representation of the surface composition. HCl apparently dissolves large oxide deposits and thus overestimates the surface concentrations of Fe, Al, and V. Conversely, several metallic ions are essentially insoluble in neutral aqueous solutions, so their surface concentration is underestimated by the tris leachate

216

Ash deposition behavior of cynara-coal blends in a PF pilot furnace  

Energy Technology Data Exchange (ETDEWEB)

Biomass is nowadays considered as a very interesting option to substitute conventional fossil fuels. Although biomass could be burnt alone, it can also be co-fired together with coal in existing power plants, at a lower cost. One of the main problems related with biomass used in thermal applications is its propensity to form ash deposits. Slagging and fouling caused by ash may derive in heat transfer losses, corrosion in the tubes or even boiler shutdown. A deposition probe has been designed and proved to study this phenomenon. Several combustion tests have been performed in a 500 kW{sub th} PF pilot test rig burning cynara blended with two coals at different shares in energy basis. Different analyses have been performed to those ash samples collected during the tests. From the results, it is observed that the quantity of collected ash in the deposition probe did not increase noticeably when increasing the biomass share up to 15% in energy basis. However, the opposite was detected in Spanish coal tests, due to its higher ash content. Major components of ash samples were aluminosilicates coming from coal clays. These components may act as protective ash coal compounds, but inorganic elements such as calcium or potassium also appeared and their presence increased with the biomass share. Although chlorine content in cynara was high, no important presence of this element was encountered in none of the ash samples collected. Experimental results agree with other experimental studies showing that aluminosilicates from coals may act as protective ash compounds, preventing chlorine deposition on heat transfer surfaces. The beneficial effect is also detected at pulverized fuel conditions. (author)

Bartolome, C.; Gil, A.; Ramos, I.

2010-11-15

217

Effects of Sediment Containing Coal Ash from the Kingston Ash Release on Embryo-Larval Development in the Fathead Minnow, Pimephales promelas (Rafinesque, 1820)  

Energy Technology Data Exchange (ETDEWEB)

The largest environmental release of coal ash in U.S. history occurred in December 2008 with the failure of a retention structure at the Tennessee Valley Authority (TVA) Kingston Fossil Plant in East Tennessee. A byproduct of coal-burning power plants, coal ash is enriched in metals and metalloids such as selenium and arsenic with known toxicity to fish including embryonic and larval stages. The effects of contact exposure to sediments containing up to 78 % coal ash from the Kingston spill on the early development of fish embryos and larvae were examined in 7-day laboratory tests with the fathead minnow (Pimephales promelas). No significant effects were observed on hatching success, incidences of gross developmental abnormalities, or embryo-larval survival. Results suggest that direct exposures to sediment containing residual coal ash from the Kingston ash release may not present significant risks to fish eggs and larvae in waterways affected by the spill.

Greeley Jr, Mark Stephen [ORNL; Elmore, Logan R [ORNL; McCracken, Kitty [ORNL; Sherrard, Rick [Tennessee Valley Authority (TVA)

2014-01-01

218

Radiological significance of coal, slag and fly ash samples from the Eastern Black Sea region  

International Nuclear Information System (INIS)

This work presents a study of natural radioactivity levels in coal and its combustion residues (fly ash and slag) used in the houses in Black Sea Region, Turkey. Coal, fly ash and slag samples were provided from different locations of the region and analyzed by gamma spectroscopy using a high-purity germanium detector (HPGe). Also, chemical analyses of these samples were carried out using energy dispersive X-ray fluorescence spectrometer. The mean 226Ra activity concentrations in coal, slag and fly ash were measured as 83, 99 and 38 Bq kg-1, respectively. The mean 232Th activity concentrations in coal, slag and fly ash were measured as 108, 113 and 50 Bq kg-1, respectively. The mean 40K activity concentrations in coal, slag and fly ash were found to be 366, 381 and 204 Bq kg-1, respectively. The potential radiological hazards associated to these materials were evaluated by calculating the radium equivalent activity (Raeq), the air absorbed gamma dose rate (D), the annual effective dose rate (AED), the external hazard index (Hex) and internal hazard index (Hin) and compared with the internationally accepted or reference values. The mean Raeq values of the coal, fly ash and slag samples were lower than the recommended maximum values 370 Bq kg-1 by the Organization for Economic Cooperation and Development (OECD). The overall mean outdoor terrestrial ga). The overall mean outdoor terrestrial gamma air absorbed dose rate in coal, fly ash and slag samples are 119, 129 and 62 nGy h-1 and the corresponding outdoor annual effective doses are 0.60, 0.32 and 0.64 mSv y-1, which is higher than the worldwide average (0.07 mSv y-1), respectively. Moreover, the enrichment factors relative to the input coal are calculated for the radionuclide contents observed. Calculated enrichment factor values for 226Ra and 232Th were found 1.14 and 1.01, respectively. (orig.)

219

EFFECT OF COAL ASH ON THE MORPHOLOGICAL, THERMAL AND MECHANICAL PROPERTIES OF POLY(METHYL METHACRYLATE)  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: English Abstract in english Composite materials of Coal ash/ Poly(Methyl Methacrylate) (ash/PMMA) were prepared/synthesized and their properties were studied by scanning electron microscopy (SEM), polarized optical microscopy (POM), differential scanning calorimetry (DSC), thermogravimetric analyzer (TGA) and universal testing [...] machine (UTM). The morphological study presented that the ash particles were well dispersed and embedded within the PMMA matrix. The DSC thermograms showed that the melting temperature (Tm) of pure PMMA is about 166 ºC which was shifted towards lower temperature when ash were incorporated in the polymer matrix. The mechanical properties of the ash/PMMA composites were enhanced up to an optimum level (ash 3 wt %) and then decreased at higher incorporation of large quantity of filler. The TGA thermograms indicated that the thermal stability of the ash/PMMA composite was enhance significantly than pure PMMA.

MUHAMMAD, ISHAQ; KHALID, SAEED; MUHAMMAD, SHAKIRULLAH; IMTIAZ, AHMAD; TAYYIBA, REHMAN.

2012-03-01

220

Natural radionuclide content of some U.K. coals and ashes  

International Nuclear Information System (INIS)

For coal burnt by the CEGB at Eggborough and Drax Power Stations the average concentrations of radioactivity in coal are 20 Bq Kg-1 for both U-238 and Th-232 series and 260 Bq Kg-1 for K-40. The ash fraction passing through the ash precipitator gave values for U-238, Th-232 and K-40 of 110, 80 and 1100 Bq Kg-1 respectively. These studies have further shown that there is no significant enhancement of radioactivity on to the ash passing through the precipitators and entering the environment. (author)

221

Genesis of some tertiary Indian coals from the chemical composition of ash - a statistical approach: Part 1  

Science.gov (United States)

In the present investigation, 37 numbers of high sulphur tertiary coal samples from Meghalaya, India have been studied on the basis of proximate and ash analysis. Various statistical tools like Bivariant Analysis, Principal Component Analysis (PCA) and Hierarchical Clustering Analysis (HCA), and also the geochemical indicators were applied to determine the dominant detrital or authigenic affinity of the ash forming elements in these coals. The genetic interpretation of coal as well as the coal ash has been carried out based on chemical compositions of high temperature ash (HTA) by using Detrital/Authigenic Index. X-Ray Diffraction (XRD) analysis was also carried out to study the mineralogy of the studied coal ashes. Both statistical tools and geochemical indicators have confirmed the detrital nature of these coals as well as the ash forming elements.

Sharma, Arpita; Saikia, Ananya; Khare, Puja; Baruah, B. P.

2014-10-01

222

Utilization of coal fly ash in solidification of liquid radioactive waste from research reactor.  

Science.gov (United States)

In this study, the potential utilization of fly ash was investigated as an additive in solidification process of radioactive waste sludge from research reactor. Coal formations include various percentages of natural radioactive elements; therefore, coal fly ash includes various levels of radioactivity. For this reason, fly ashes have to be evaluated for potential environmental implications in case of further usage in any construction material. But for use in solidification of radioactive sludge, the radiological effects of fly ash are in the range of radioactive waste management limits. The results show that fly ash has a strong fixing capacity for radioactive isotopes. Specimens with addition of 5-15% fly ash to concrete was observed to be sufficient to achieve the target compressive strength of 20 MPa required for near-surface disposal. An optimum mixture comprising 15% fly ash, 35% cement, and 50% radioactive waste sludge could provide the solidification required for long-term storage and disposal. The codisposal of radioactive fly ash with radioactive sludge by solidification decreases the usage of cement in solidification process. By this method, radioactive fly ash can become a valuable additive instead of industrial waste. This study supports the utilization of fly ash in industry and the solidification of radioactive waste in the nuclear industry. PMID:24638274

Osmanlioglu, Ahmet Erdal

2014-05-01

223

Chemical and petrographical characterization of feed coal, fly ash and bottom ash from the Figueira Power Plant, Parana, Brazil  

Energy Technology Data Exchange (ETDEWEB)

The aim of the present study is the petrographic and chemical characterization of the coal at the Figueira Power Plant, Parana, Brazil, prior and after the beneficiation process and the chemical characterization of fly and bottom ashes generated in the combustion process. Petrographic characterization was carried out through maceral analysis and vitrinite reflectance measurements. Chemical characterization included proximate analysis, determination of calorific value and sulphur content, ultimate analysis, X-ray diffraction, X-ray fluorescence, Inductively Coupled Plasma - Mass Spectrometry (ICP-MS) and Inductively Coupled Plasma - Atomic Emission Spectrometry (ICP-AES) analysis, and determination of Total Organic Carbon (TOC) content. Vitrinite reflectance analyses indicate a high volatile B/C bituminous coal (0.61 to 0.73% Rrandom). Maceral analyses show predominance of the vitrinite maceral group (51.6 to 70.9 vol.%, m.m.f). Except of the Run of mine (ROM) coal sample, the average calorific value of the coals is 5205 kcal/kg and ash yields range from 21.4 to 38.1 wt.%. The mineralogical composition (X-ray diffraction) of coals includes kaolinite, quartz, plagioclase and pyrite, whereas fly and bottom ashes are composed by mullite, ettringite, quartz, magnetite, and hematite. Analyses of major elements from coal, fly and bottom ashes indicate a high SiO{sub 2}, Al{sub 2}O{sub 3}, and Fe{sub 2}O{sub 3} content. Trace elements analysis of in-situ and ROM coals by ICP-MS and ICP-AES show highest concentration in Zn and As. Most of the toxic elements such as As, Cd, Cr, Mo, Ni, Pb, and Zn are significantly reduced by coal beneficiation. Considering the spatial distribution of trace elements in the beneficiated coal samples, which were collected over a period of three months, there appears to be little variation in Cd and Zn concentrations, whereas trace elements such as As, Mo, and Pb show a larger variation. In the fly and bottom ashes, the highest concentrations of trace elements were determined for Zn and As. When compared with trace element concentrations in the feed coal, fly ashes show a significant enrichment in most trace elements (As, B, Be, Cd, Co, Cr, Cu, Li, Mn, Mo, Ni, Pb, Sb, Tl, and Zn), suggesting a predominantly volatile nature for these elements. In contrast, Sn is distributed evenly within the different ash types, whereas U shows depleted concentration in both bottom and fly ash samples. According to the International Classification of in-seam coals the Cambui coals are of para/ortho bituminous rank of low grade (except for the ROM sample), and are characterized by the predominance of vitrinite macerals. (author)

Levandowski, Janaina; Kalkreuth, Wolfgang [Instituto de Geociencias, UFRGS, Av. Bento Goncalves, 9500, 91501-970 Porto Alegre, RS (Brazil)

2009-01-31

224

EFFECTS OF IRON CONTENT IN COAL COMBUSTION FLY ASHES ON SPECIATION OF MERCURY  

Science.gov (United States)

The paper discusses the effects of iron content in coal combustion fly ashes on speciation of mercury. (NOTE: The chemical form of mercury species in combustion flue gases is an important influence on the control of mercury emissions from coal combustion). The study focused on th...

225

Impact of coal and rice husk ash on the quality and chemistry of cement clinker  

International Nuclear Information System (INIS)

Utilization of rice husk as an alternative fuel for coal is of interest due to its availability in huge quantities in Pakistan and also because its combustion is environmental pollution friendly as it generates much less SOX due to its much lower sulphur content (0.1-0.3%) compared to sulphur content in coals, particularly indeginous coals ranging from 0.6-14.8%. The purpose of present study was to examine the impact of co-firing of rice husk and coal on the quality of cement clinker so as to substitute expensive imported coal with the abundantly available cheaper rice husk to reduce the cost of production of the cement. For this investigation raw feed mix (mixture of limestone, clay, bauxite and laterite in predetermined proportions) used for cement manufacture was mixed with predetermined varying proportions of coal ash and rice husk ash and placed inside a muffle furnace at 1200 degree C - 1500 degree C i-e the temperatures prevailing in the industrial cement kilns, for various periods of time to obtain cement clinker. The quality and chemistry of cement clinker thus produced in the laboratory was experimentally studied to ensure the quality of cement clinker that would be obtained by co-firing of rice husk and coal in different proportions in industrial cement kilns as the coal ash and rice husk ash produced during combustion will get mixed with cement clinker in industrial kilns. The results indicated that there was decrease in the Lime Saturation Factor, Free Liase in the Lime Saturation Factor, Free Lime and Tricalcium Silicate (C3S) content and increase in the Dicalcium Silicate (C2S) content by increasing the rice husk ash and decreasing the coal ash proportion in the clinker. (author)

226

Solidification of coal fly ash using hydrothermal processing method  

Energy Technology Data Exchange (ETDEWEB)

Solidification of Coal Fly-ash (CFA) has been carried out using a hydrothermal processing method. In the hydrothermal processing, the CFA was first compacted in a mold at 20 - 50 MPa, and then hydrothermally cured in an autoclave. The hydrothermal curing was performed at 150 - 250{sup o}C for 15 - 60 h. The experimental results showed that NaOH solution, Ca(OH){sub 2} content, compaction pressure, autoclave curing temperature and time significantly affected the strength of solidified bodies. The most important strength-producing constituent in the solidified bodies produced with CFA was tobermorite, or tobermorite-like calcium silicate hydrate. When the CaO/SiO{sub 2} ratio of the starting material was close to 0.83, tobermorite readily formed and the formed tobermorite enhanced the strength of solidified bodies. The tensile strength determined by the Brazilian test reached more than 10 MPa under the hydrothermal processing. As such, the hydrothermal processing method may provide a high potential for recycling CFA on a large scale.

Jing, Z.; Matsuoka, N.; Jin, F.; Yamasaki, N.; Suzuki, K.; Hashida, T. [Tohoku University, Miyagi (Japan). Graduate School for Environmental Studies

2006-03-15

227

Utilization and disposal of fly ash and other coal residues in terrestrial ecosystems: a review  

Energy Technology Data Exchange (ETDEWEB)

Impacts of land-oriented utilization and disposal of various coal combustion residues are summarized. The physical and chemical properties of coal ashes are dependent on the coal's geological origin, combustion condition, efficiency of particulate removal, and degree of weathering before final disposal. Coal residues, applied on cropland, are not practical sources of essential plant nutrients N, P, and K; however, they can effectively serve as a supplementary supply of Ca, S, B, Mo, and Se to soils. Fly ash could also be an effective amendment in neutralizing soil acidity. Many of the observed chemical and biological effects of fly ash applications to soils resulted from the increased activities of Ca/sup 2 +/ and OH/sup -/ ions. Most unweathered fly ashes, especially those coming from the subbituminous and lignite coals of the western US, are high in these constituents and usually will cause high soil salinity. The accumulation of B, Mo, Se, and soluble salts in fly ash-amended soils appear to be the most serious constraints associated with land application of fly ash to soil.

Adriano, D.C.; Page, A.L.; Elseewi, A.A.; Chang, A.C.; Straughan, I.

1980-07-01

228

Determination of ash content in coal by the forward-scattering method of low-energy gamma radiation  

International Nuclear Information System (INIS)

The paper describes a method for determination of ash content in coal, based on the forward-scattering phenomenon of low-energy gamma radiation. The paper evaluates the effect of measuring geometry, granulation, mass, sample packing and chemical constitution of coal on the accuracy of measured ash content in coal. There is given a new manner to calculate ash content that uses some parameters of the forward-scattered gamma radiation spectrum. (author)

229

Anion exchange method for the sequential determination of uranium, thorium and lead-210 in coal and coal ash  

International Nuclear Information System (INIS)

A radiochemical procedure is presented for the sequential determination of uranium isotopes, thorium isotopes, and 210Pb in coal and coal ash. This procedure consists of dry ashing the sample, a nitric-hydrofluoric acid dissolution, removal of iron with ether extractions, and separation of the elements of interest by anion exchange chromatography. Uranium and thorium isotopes are measured by alpha spectrometry, while 210Pb is measured by beta counting its daugther activity, 210Bi. For 10 g coal samples and 1 g ash samples, the chemical yields for the radioactivities measured were 70-80%, and the relative standard deviations for replicate analyses were generally less than 9%. The deviations of the means from the reference values were within the combined errors of each and were usually less than +-5%. Minimum detectable activities were about 0.02 pCi for uranium and thorium isotopes and 0.2 pCi for 210Pb. (author)

230

Mineral sequestration of CO(2) by aqueous carbonation of coal combustion fly-ash.  

Science.gov (United States)

The increasing CO(2) concentration in the Earth's atmosphere, mainly caused by fossil fuel combustion, has led to concerns about global warming. A technology that could possibly contribute to reducing carbon dioxide emissions is the in-situ mineral sequestration (long term geological storage) or the ex-situ mineral sequestration (controlled industrial reactors) of CO(2). In the present study, we propose to use coal combustion fly-ash, an industrial waste that contains about 4.1 wt.% of lime (CaO), to sequester carbon dioxide by aqueous carbonation. The carbonation reaction was carried out in two successive chemical reactions, first, the irreversible hydration of lime. second, the spontaneous carbonation of calcium hydroxide suspension. A significant CaO-CaCO(3) chemical transformation (approximately 82% of carbonation efficiency) was estimated by pressure-mass balance after 2h of reaction at 30 degrees C. In addition, the qualitative comparison of X-ray diffraction spectra for reactants and products revealed a complete CaO-CaCO(3) conversion. The carbonation efficiency of CaO was independent on the initial pressure of CO(2) (10, 20, 30 and 40 bar) and it was not significantly affected by reaction temperature (room temperature "20-25", 30 and 60 degrees C) and by fly-ash dose (50, 100, 150 g). The kinetic data demonstrated that the initial rate of CO(2) transfer was enhanced by carbonation process for our experiments. The precipitate calcium carbonate was characterized by isolated micrometric particles and micrometric agglomerates of calcite (SEM observations). Finally, the geochemical modelling using PHREEQC software indicated that the final solutions (i.e. after reaction) are supersaturated with respect to calcium carbonate (0.7 < or = saturation index < or = 1.1). This experimental study demonstrates that 1 ton of fly-ash could sequester up to 26 kg of CO(2), i.e. 38.18 ton of fly-ash per ton of CO(2) sequestered. This confirms the possibility to use this alkaline residue for CO(2) mitigation. PMID:18539389

Montes-Hernandez, G; Pérez-López, R; Renard, F; Nieto, J M; Charlet, L

2009-01-30

231

Mineral sequestration of CO2 by aqueous carbonation of coal combustion fly-ash  

International Nuclear Information System (INIS)

The increasing CO2 concentration in the Earth's atmosphere, mainly caused by fossil fuel combustion, has led to concerns about global warming. A technology that could possibly contribute to reducing carbon dioxide emissions is the in-situ mineral sequestration (long term geological storage) or the ex-situ mineral sequestration (controlled industrial reactors) of CO2. In the present study, we propose to use coal combustion fly-ash, an industrial waste that contains about 4.1 wt.% of lime (CaO), to sequester carbon dioxide by aqueous carbonation. The carbonation reaction was carried out in two successive chemical reactions, first, the irreversible hydration of lime. CaO + H2O ? Ca(OH)2 second, the spontaneous carbonation of calcium hydroxide suspension. Ca(OH)2 + CO2 ? CaCO3 + H2O A significant CaO-CaCO3 chemical transformation (approximately 82% of carbonation efficiency) was estimated by pressure-mass balance after 2 h of reaction at 30 deg. C. In addition, the qualitative comparison of X-ray diffraction spectra for reactants and products revealed a complete CaO-CaCO3 conversion. The carbonation efficiency of CaO was independent on the initial pressure of CO2 (10, 20, 30 and 40 bar) and it was not significantly affected by reaction temperature (room temperature '20-25', 30 and 60 deg. C) and by fly-ash dose (50, 100, 150 g). The kinetic data dem(50, 100, 150 g). The kinetic data demonstrated that the initial rate of CO2 transfer was enhanced by carbonation process for our experiments. The precipitate calcium carbonate was characterized by isolated micrometric particles and micrometric agglomerates of calcite (SEM observations). Finally, the geochemical modelling using PHREEQC software indicated that the final solutions (i.e. after reaction) are supersaturated with respect to calcium carbonate (0.7 ? saturation index ? 1.1). This experimental study demonstrates that 1 ton of fly-ash could sequester up to 26 kg of CO2, i.e. 38.18 ton of fly-ash per ton of CO2 sequestered. This confirms the possibility to use this alkaline residue for CO2 mitigation

232

Apparatus and method for direct measurement of coal ash sintering and fusion properties at elevated temperatures and pressures  

Science.gov (United States)

A high-pressure microdilatometer is provided for measuring the sintering and fusion properties of various coal ashes under the influence of elevated pressures and temperatures in various atmospheres. Electrical resistivity measurements across a sample of coal ash provide a measurement of the onset of the sintering and fusion of the ash particulates while the contraction of the sample during sintering is measured with a linear variable displacement transducer for detecting the initiation of sintering. These measurements of sintering in coal ash at different pressures provide a mechanism by which deleterious problems due to the sintering and fusion of ash in various combustion systems can be minimized or obviated.

Khan, M. Rashid (Morgantown, WV)

1990-01-01

233

Absorption of selenium from coal fly ash-amended soil by Astragalus racemosus  

Energy Technology Data Exchange (ETDEWEB)

Plants normally growing on soils in the Northeastern United States contain about 0.05ppM of selenium on a dry weight basis. It has been shown that plants growing on soils amended with coal fly ash or on fly ash alone absorbed notably higher concentrations of selenium. It is well know that certain plant species of the genus Astragalus which grow over a wide area of the Western United States accumulate very high concentrations of the element. Fly ash and some of these western soils contain selenium in the same concentration range. It was of interest therefore to study the availability of this toxic element in fly ash to a selenium accumulator plant. In the work reported, one of the well known Astragalus selenium accumulator species was grown to maturity in pots of soil amended with coal fly ash and then analyzed for total selenium.

Gutenmann, W.H.; Lisk, D.J.

1979-09-01

234

A technique for measuring the ash content of coal in a tailings stream  

International Nuclear Information System (INIS)

A technique is described for developing an on-line instrument measuring the ash content of coal in a coal washery tailings stream. The method employs two radioisotope-detector systems, a 137Cs density transmission gauge and a Compton backscatter x-ray gauge with 109Cd. To evaluate the technique under typical plant conditions, a full-scale slurry measuring loop was constructed. The accuracy of the ''dry basis'' ash measurement, in a measurement time of 500 s was +- 4% ash (95% confidence level) for an ash range from 48 to 66% ash with the solids content varying from 18 to 35%. A calibration procedure is described which requires no knowledge of the values of the solids contents of the slurries used for calibration. (author)

235

Determination of the ash content of some Nigerian coal samples by gamma-ray methods  

International Nuclear Information System (INIS)

Regression equations, relating conventionally measured ash contents to measured attenuation coefficients of coal samples from the Lafia Obi coal mines in the Plateau State of Nigeria have been obtained using three different ?-rays energies of 0.0607, 0662 and 1.33 MeV from 241Am, 137Cs and 60Co sources, respectively. An approximate linear relationship exists at the higher energy, where Compton scattering dominates. The method was found to be useful for a rapid and accurate measurement of the ash content of coal samples from the area. (Author)

236

Solid and fly ash materials ofbrown coal power plants, their characteristics and utilisation  

OpenAIRE

coal-fired power plants, a significant amount of residues is produced, depending on the technical parameters of coal separation and firing equipment. A large quantity of solid and fly ash and, in the case of flue gas desulphurisation, REA gypsum and wash-water is produced. The quantity of residues depends primarily on the ash and sulphur content of the fuel.Coal has a significant role in energy production and represents a considerable quantity in electric energy generation. At the turn of the...

Kovács Ferenc; Mang Béla

2002-01-01

237

Growth response of two grasses and a legume on coal fly ash amended strip mine spoils  

Energy Technology Data Exchange (ETDEWEB)

The use of fly ash as an amendment for strip mine soils was studied under field conditions. Three plant species - Agrostis tenuis var. Highlander, Festuca arundinacea, and Lespedeza cuneata - were grown in strip mine plots. Half of the plots were treated with an equivalent of 70 metric tons per hectare of coal fly ash and half were untreated. Biomass production ranged from 5 to 30 times higher in fly ash treated plots compared to untreated plots. The higher production rates are thought to be due to the effects of fly ash on soil moisture holding capacity and improvement in soil texture. No toxic effects to the plants were observed. 14 refs., 1 tab.

Fail, J. Jr.

1987-01-01

238

Determination of pit-coal ash content with the use of an (?,n) neutron source  

International Nuclear Information System (INIS)

Activation with fast neutrons from a Pu/Be source enables the 28Si(n, p)28Al and 27Al(n, p)27Mg reactions to be utilized. Seventy-two samples of pit coals with ash contents ranging from 3 to 40% were measured. The calibration function between ash content and both 1.78 and 0.84-MeV ?-ray counts was linear. The standard deviation was 0.9% for a 17% ash content and 1.4% over the whole range of ash contents. Comparison with rapid combustion and fluorescence scattering methods is discussed. (Auth.)

239

Radiochemical tecniques applied to laboratory studies of water leaching of heavy metals from coal fly ash  

International Nuclear Information System (INIS)

Assessment of the potential environmental impact of heavy metals (HM) mobilized by coal-fired plants showed that water leaching of HM from pulverized fuel ash may for certain HM constitute an important pathway to the aquatic environment. This process was therefore investigated in more detail by laboratory experiments. Batch experiments were performed in order to simulate ash pond conditions, whereas column experiments were carried out to represent water leaching from fly ash deposits. Using highly sensitive radiochemical techniques such as radioactive tracers and neutron activation of fly ash the fate of a single HM could be easily followed even in very low concentration experiments. Employing radioisotopic tracers the distribution coefficients of simple ionic forms of As, Sb, Bi, Se, Te, Cr, Mo, W, Ni, Cd in a coal fly ash/water system could be determined as a function of pH. Results obtained on the absorption and desorption behaviour of HM on coal fly ash can be explained in part on the basis of the surface predominance and the aqueous chemistry of single ionic, mainly anionic, forms of the relative elements. But ion exchange and coprecipitation phenomena also seem to be important processes. The nature and concentration of ions contained originally in the water used (distilled water, fly ash leachate and seawater) were found to have a strong influence on the sorptive behaviour of HM on coal ashes. The high degree of applicability of radiochemical and nuclear techniques to coal ash water leaching problems has been demonstrated and further points for subsequent research in this field possibly using nuclear techniques are indicated. (author)

240

Behaviour of coal mineral matter in sintering and slagging of ash during the gasification process  

OpenAIRE

The mineral matter in typical feed coals used in South African gasification processes and the ash derived from gasifying such coals have been investigated using a variety of mineralogical, chemical and electron microscope techniques. The mineral matter in the feed coals consists mainly of kaolinite, with minor proportions of quartz, illite, dolomite, calcite and pyrite plus traces of rutile and phosphate minerals. The calcite and dolomite occur in veins within the vitrinite macerals, and are ...

Matjie, Ratale Henry; French, David; Ward, Colin R.; Pistorius, Petrus Christiaan; Li, Zhongsheng

2011-01-01

241

Solid and fly ash materials ofbrown coal power plants, their characteristics and utilisation  

Directory of Open Access Journals (Sweden)

Full Text Available coal-fired power plants, a significant amount of residues is produced, depending on the technical parameters of coal separation and firing equipment. A large quantity of solid and fly ash and, in the case of flue gas desulphurisation, REA gypsum and wash-water is produced. The quantity of residues depends primarily on the ash and sulphur content of the fuel.Coal has a significant role in energy production and represents a considerable quantity in electric energy generation. At the turn of the millenary, about 4 billion tones of black coal and 800 million tones of brown coal and lignite are produced in the world annually. Depending on the ash content of the coals ? it varies between 5-8% and 30-35% ?, the quantity of solid and fly ash produced by firing is 1.0-1.5 billion tones per year. The quantity of residues of this kind accumulated in the past amounts to 100 billion tones.As far as the residues of coal-fired power plants are concerned, the annual fuel demand of the power plants of the Rhenish brown coal basin, where the average ash content of lignite is 7% and the average sulphur content is 0.2-0.8%, is 1 Mt referred to a power plant capacity of 100 MW. 60-70 kt solid + fly ash and, in the case of flue gas desulphurisation, 12-15 kt of gypsum is produced annually, referred to a capacity of 100 MW. In the East German areas, after the reconstruction of power plants, 30-50 kt of fly ash and, because of the higher sulphur content, 25-30 kt of gypsum and 4-5000 m3 of wash-water is produced annually, referred to a capacity of 100 MW.The composition of Hungarian lignite is significantly different to that of Rhenish brown coal. The ash content and combustible sulphur content of domestic lignite is considerably higher. The ash content of lignite varies between 15 and 25%, the average is 20%. In Visonta, 160-200 tones of solid + fly ash is produced annually, referred to a power plant capacity of 100 MW. With the flue gas desulphuriser installed recently, one can expect a gypsum quantity of 40-60 kt/year, referred to a capacity of 100 MW.

Kovács Ferenc

2002-09-01

242

Dissolution of Rare Earth Elements from Coal Fly Ash Particles in a Dilute H2SO4 Solvent  

Directory of Open Access Journals (Sweden)

Full Text Available Recently, the worldwide supply of rare earth element (REE resources will be severely restricted. On the other hand, coal fly ash particles emitted from coal-fired electric power plants contain relatively high concentrations of REEs. The contents of REEs in coal fly ash are regularly several hundreds of ppmw. In order to extract and recover REEs from coal fly ash particles, as a first step, we have investigated their dissolution behavior in a dilute H2SO4 solvent. The REE content of coal fly ash specimens has been precisely determined, and their presence in the ash component of the original coal and their enrichment in coal fly ash particles during coal combustion have been suggested. REEs in coal fly ash dissolve gradually in H2SO4 over time, and this implies two types of occurrences of the REEs in coal fly ash particles. By applying the unreacted core model to the dissolution behavior of REEs in a H2SO4 solvent, we can explain both types of occurrences.

Shunsuke Kashiwakura

2013-05-01

243

Characterization of bottom ashes from coal pulverized power plants to determine their potential use feasibility  

International Nuclear Information System (INIS)

The disposal of coal by products represents environmental and economical problems around the world. Therefore, the reuse and valorisation of this waste has become an important issue in the last decades. While high-value construction products containing fly ash were developed and its use is actually totally accepted as an addition to cement, the use of the bottom ash as supplementary cementitious material has not been allow. This paper examines the chemical and physical properties of fly ashes and bottom ashes from two different coal power plants in order to compare them and analyse the potential feasibility of bottom ash as cement replacement. The mechanical properties of cement mortars made with different percentages of both ashes were also study. The results obtained showed similar chemical composition of both kinds of ashes. The compressive strength values of mortars with 10 % and 25 % of cement replacement (at 28 days) were above the limits established in European standards and there were not significant differences between fly ash and bottom ash from both origins. (Author)

244

Characterization of bottom ashes from coal pulverized power plants to determine their potential use feasibility  

Energy Technology Data Exchange (ETDEWEB)

The disposal of coal by products represents environmental and economical problems around the world. Therefore, the reuse and valorisation of this waste has become an important issue in the last decades. While high-value construction products containing fly ash were developed and its use is actually totally accepted as an addition to cement, the use of the bottom ash as supplementary cementitious material has not been allow. This paper examines the chemical and physical properties of fly ashes and bottom ashes from two different coal power plants in order to compare them and analyse the potential feasibility of bottom ash as cement replacement. The mechanical properties of cement mortars made with different percentages of both ashes were also study. The results obtained showed similar chemical composition of both kinds of ashes. The compressive strength values of mortars with 10 % and 25 % of cement replacement (at 28 days) were above the limits established in European standards and there were not significant differences between fly ash and bottom ash from both origins. (Author)

Menendez, E.; Alvaro, A. M.; Argiz, C.; Parra, J. L.; Moragues, A.

2013-07-01

245

The evaluation of geopolymer properties prepared by alkali activation of black coal ashes with high content of loss on ignition  

OpenAIRE

The utilization of fly ashes in Slovakia is lower than in other countries and dumping of fly ashes prevails. The dumping changeschemical and phase composition of fly ashes and so it decreases possibilities for their utilization. Fly ashes are mainly used in buildingindustry, where the content of loss on ignition (LOI) is limited due to standards. Black coal fly ashes produced in Slovakia have a highcontent of loss on ignition – more than 20 % - so they straight utilization in building indus...

Michalíková Františka; Krinická Ivana; Kolesárová Miroslava; Sisol Martin; Praš?áková Mária

2010-01-01

246

Preliminary report on coal pile, coal pile runoff basins, and ash basins at the Savannah River Site: effects on groundwater  

Energy Technology Data Exchange (ETDEWEB)

Coal storage piles, their associated coal pile runoff basins and ash basins could potentially have adverse environmental impacts, especially on groundwater. This report presents and summarizes SRS groundwater and soil data that have been compiled. Also, a result of research conducted on the subject topics, discussions from noted experts in the field are cited. Recommendations are made for additional monitor wells to be installed and site assessments to be conducted.

Palmer, E. [Westinghouse Savannah River Company, AIKEN, SC (United States)

1997-04-28

247

Ash characterization in laboratory-scale oxy-coal combustor  

Science.gov (United States)

Oxygen enriched coal (oxy-coal) combustion is a developing technology. During oxy-coal combustion, combustion air is separated and the coal is burned in a mixture of oxygen and recycled flue gas. The resulting effluent must be further processed before the C02 can be compressed, t...

248

Mercury in coals and fly ashes from Republika and Bobov Dol Thermoelectric Power Plants  

International Nuclear Information System (INIS)

Feed coal and fly ash samples were collected at Republika and Bobov Dol thermoelectric power plants (TPPs). The fly ashes (FAs) were collected from three rows of the hot-side electrostatic precipitators (ESPs) array. Each sample was wet-screened at 100, 200, 325 and 500 mesh. The coals and fly ashes were characterized with regard to their petrological and chemical composition (including mercury content) and to their surface area properties. The calculated enrichment factor (EF) shows that the Hg concentrations in the bulk coal samples from Republika and Bobov Dol TPPs are 2.19 and 1.41, respectively. In some coal size fractions the EF can be up to 4 times higher than the Clarke value. The calculated EF for fly ashes shows that the Hg concentrations in the bulk samples studied are lower (between 0.03 and 0.32) than the Clarke value. The most enriched in Hg are the fly ashes from the 3rd ESP row of Republika TPP. The Hg distribution in bulk FAs taken from different rows of the electrostatic precipitators of both TPPs studied shows well established tendency of gradual increase in the Hg content from the 1st to the 2nd and 3rd ESP rows. The correlation between Hg content and surface area, mesopore and micropore volume of fly ashes was also done in the present investigation. (authors)

249

Integrated production/use of ultra low-ash coal, premium liquids and clean char. [Quarterly] report, December 1, 1991--February 29, 1992  

Energy Technology Data Exchange (ETDEWEB)

The first step in the integrated, mufti-product approach for utilizing Illinois coal is the production of ultra low-ash coal. Subsequent steps convert low-ash coal to high-value, coal-derived, products. The ultra low-ash coal is produced by solubilizing coal in a phenolic solvent under ChemCoal{trademark} process conditions, separating the coal solution from insoluble ash, and then precipitating the clean coal by dilution of the solvent with methanol. Two major products, liquids and low-ash char, are then produced by mild gasification of the low-ash coal. The low ash-char is further upgraded to activated char, and/or an oxidized activated char which has catalytic properties. Characterization of products at each stage is part of this project.

Kruse, C.W. [Illinois State Geological Survey, Champaign, IL (United States)

1992-08-01

250

An application of hydrothermally crystallized coal ashes for waste water treatment, 2  

International Nuclear Information System (INIS)

To provide an application of combustion coal ash, hydrothermal reaction of fly ash (FA) and clinker ash (CA) is performed and an investigation is carried out to determine the capability of the P type zeolite produced from these ashes to adsorb heavy metal ions. Hydrothermal reaction of FA and CA at 95 - 100 deg C is conducted with various concentrations of sodium hydroxide for various reaction times. Both types of ash are found to easily undergo crystallization to form P type zeolite (PZ) and hydroxy sodalite (HS) when treated with a sodium hydroxide solution (sodium hydroxide/coal ash = 10 v/w) for 18 hours. The FA-PZ and CA-PZ produced by the hydrothermal treatment have degrees of crystallinity in the range of 40 - 60 percent. It is seen that the degree of crystallinity gradually increases with increasing treatment time. The cristallinity of hydrothermally treated coal ash is also shown to have good correlation with the base substitution capacity and the maximum adsorption of ammonium ion. Furthermore, they are shown to effectively adsorb metal ions, in particular those of lead, cadmium and strontium. It is suggested that they may serve as an enrichment agent for low-level radioactive nuclides produced in nuclear power plants. They also seem to have the possibility of serving as a metal elution preventive for industrial wastes of some special types. (Nogami, K.)

251

Manufacture of lightweight aggregates utilizing coal fly ash. Sekitanbai no jinko keiryo kotsuzaika  

Energy Technology Data Exchange (ETDEWEB)

Artificial and lightweight aggregates of coal ash were reported developed for the reutilization of coal ash by-produced from the coal burning power generation. Using fly ash contained by 70 to 80% in the coal ash as primary material, the adopted method was to pelletize it to form a spherical mass having a specified distribution of grain size and calcine it by the combustion heat from the unburnt coal remaining therein. The kiln method and sinterstrand method being compared, the latter was concluded to excel for the calcination. The production plant is composed of pneumatic transport unit, silo, quantitative feeder, conveyer, mixer/kneader, pelletizer, calciner, etc. to produce the aggregate by processing the fly ash as primary material through that plant. The thus produced aggregate was evaluated in compressive strength, bending test, shearing test, gas compression test as concrete, etc., and consequently known to be appropriate as concrete lightweight aggregate and further prospective for the use of aquatic plantation and improvement in soil drainage. The present method is advantageous with, among others, utilizing the industrial waste and activating the unburnt residue. 17 figs., 6 tabs.

Ishii, K.; Koreishi, T. (Kyushu Electric Power Co. Inc., Fukuoka (Japan)); Mihara, J.; Sato, S.; Terukina, J. (Kobe Steel, Ltd., Kobe (Japan))

1992-05-10

252

Coal ash usage in environmental restoration at the Hanford site  

Energy Technology Data Exchange (ETDEWEB)

The ash stockpiled next to the 284E steam plant is mixed fly ash, bottom ash, and slag. The ash consists of (1) baghouse residue and (2) a mixture of bottom ash and slag which is washed out of the bottom of the boilers daily. In 1991, a Toxicity Characteristic Leaching Procedure (TCLP) was performed on several samples of this ash (Hazen Research 1991). This procedure is designed to determine the mobility of organic and inorganic anatytes present in liquid, solid, or multiphasic wastes (EPA 1994). The ash tested came from surge bins, conveyor samples, and bottom ash and fly ash from the boilers at 284E. Antimony, cadmium, germanium, molybdenum, silver, thallium, tungsten, and vanadium were tested for, but on all samples were below detection Limits for the testing method. Analytes present in relatively high concentrations (but less than one part per thousand) included barium, boron, chromium, fluorine, and zinc. The size of ash particles passing through a Taylor sieve series was very evenly distributed from 1 to 200m.

Scanlon, P.L.; Sonnichsen, J.C.; Phillips, S.J.

1994-08-01

253

Preparation of low-ash products from Slovak sub-bituminous coals - a material balance  

International Nuclear Information System (INIS)

The fines of sub-bituminous coals from the Cigel and the Handlova Collieries in use as steam coal in coal-fired power plant were subjected to washing in a water-only cyclone (WOC) with the aim to obtain suitable input material for organic compounds extraction. The WOC with a diameter of 150 mm and a cone part consisting of three angle sections 135 grad - 75 grad - 20 grad was applied. Vortex finder (overflow) and spigot (underflow) diameters were of 68 mm and 14.6 mm, respectively. Two basic products overflow and underflow were obtained. The third one, slurry or circulating charge was also considered into total material balance of washing. Thus, the contents of ash, combustible matter, SiO2, Al2O3, CaO, MgO, FeTOTAL, STOTAL, SSULPHIDIC and As were determined in the products of washing. Subsequently, on the basis of analyses the recoveries of individual components into products of washing were calculated. The washing resulted in the obtaining of significantly de-ashed coal at the overflow of WOC. In such way a washed coal with ash content in dry basis of 6.99 % at a mass yield of 20.74 % was won in the case of coal from the Cigel Colliery. Similarly, in the case of coal from the Handlova Colliery and its eastern field the products with ash content in dry basis of 7.70 % and 9.01 % at mass yield of 29.37 % and 29.50 % were obtained. Finally, the washing resulted in over 90 % ash rejection and about 70 % tn over 90 % ash rejection and about 70 % total sulphur rejection. (authors)

254

Simulation of Coal Ash Particle Deposition Experiments (Copyright 2011, American Chemical Society)  

Energy Technology Data Exchange (ETDEWEB)

Existing experimental ash particle deposition measurements from the literature have been simulated using the computational fluid dynamics (CFD) discrete phase model (DPM) Lagrangian particle tracking method and an existing ash particle deposition model based on the Johnson?Kendall?Roberts (JKR) theory, in the Fluent commercial CFD code. The experimental heating tube was developed to simulate ash temperature histories in a gasifier; ash-heating temperatures ranged from 1873 to 1573 K, spanning the ash-melting temperature. The present simulations used the realizable k?? turbulence model to compute the gas flow field and the heat transfer to a cooled steel particle impact probe and DPM particle tracking for the particle trajectories and temperatures. A user-defined function (UDF) was developed to describe particle sticking/rebounding and particle detachment on the impinged wall surface. Expressions for the ash particle Young’s modulus in the model, E, versus the particle temperature and diameter were developed by fitting to the E values that were required to match the experimental ash sticking efficiencies from several particle size cuts and ash-heating temperatures for a Japanese bituminous coal. A UDF that implemented the developed stiffness parameter equations was then used to predict the particle sticking efficiency, impact efficiency, and capture efficiency for the entire ash-heating temperature range. Frequency histogram comparisons of adhesion and rebound behavior by particle size between model and experiments showed good agreement for each of the four ash-heating temperatures. However, to apply the present particle deposition model to other coals, a similar validation process would be necessary to develop the effective Young’s modulus versus the particle diameter and temperature correlation for each new coal.

Ai, Weiguo; Kuhlman, John M

2011-01-20

255

Geochemistry of ultra-fine and nano-compounds in coal gasification ashes: a synoptic view.  

Science.gov (United States)

The nano-mineralogy, petrology, and chemistry of coal gasification products have not been studied as extensively as the products of the more widely used pulverized-coal combustion. The solid residues from the gasification of a low- to medium-sulfur, inertinite-rich, volatile A bituminous coal, and a high sulfur, vitrinite-rich, volatile C bituminous coal were investigated. Multifaceted chemical characterization by XRD, Raman spectroscopy, petrology, FE-SEM/EDS, and HR-TEM/SEAD/FFT/EDS provided an in-depth understanding of coal gasification ash-forming processes. The petrology of the residues generally reflected the rank and maceral composition of the feed coals, with the higher rank, high-inertinite coal having anisotropic carbons and inertinite in the residue, and the lower rank coal-derived residue containing isotropic carbons. The feed coal chemistry determines the mineralogy of the non-glass, non-carbon portions of the residues, with the proportions of CaCO? versus Al?O? determining the tendency towards the neoformation of anorthite versus mullite, respectively. Electron beam studies showed the presence of a number of potentially hazardous elements in nanoparticles. Some of the neoformed ultra-fine/nano-minerals found in the coal ashes are the same as those commonly associated with oxidation/transformation of sulfides and sulfates. PMID:23584038

Kronbauer, Marcio A; Izquierdo, Maria; Dai, Shifeng; Waanders, Frans B; Wagner, Nicola J; Mastalerz, Maria; Hower, James C; Oliveira, Marcos L S; Taffarel, Silvio R; Bizani, Delmar; Silva, Luis F O

2013-07-01

256

Characterisation of coal fly ash from thermal power plants in India  

International Nuclear Information System (INIS)

Fly ash collected from 22 thermal power stations spread over the country were analysed for various elements such as As, Ca, Ce, Co, Cr, Cu, Eu, fe, Hf, K, La, Lu, Mn, Na, Ni, Pb, Rb, Se, Sb, Sc, Sm, Sr, Ti, V, Yb, Zn etc. using energy dispersive X-ray fluorescence (EDXRF) and instrumental neutron activation analysis (INAA) methods. The results show that the concentrations of these elements vary widely but are within the normal range of values cited in the literature. In India, apart from coal, lignite is also burnt in the power plants. The ash content of lignite is only 7%. Most of the trace elements except sulphur get enriched (in terms of weight concentrations) in the process of combustion. The concentration of trace elements are 1.5 to 3 times in the lignite ash as compared to coal fly ash. Inter element correlations in the fly ash samples showed associations of Ti with Fe, Si with K and Cu, Zn with Pb, K with Rb and Ca with Sr. The fly ash samples in two sizes 53 ?m). Leaching of fly ash was also carried out by agitating the fly ash at pH 4.0 for 24 hrs. The residues were also analysed for major and trace elements. (author). 7 refs., 4 tabselements. (author). 7 refs., 4 tabs

257

Technical note: Vetiver can grow on coal fly ash without DNA damage.  

Science.gov (United States)

Fly ash is a by-product of coal-fired electricity generation plants. The prevalent practice of disposal is as slurry of ash and water to open lands or ash ponds located near power plants and this has lain to waste thousands of hectares all over the world. Wind and leaching are often the causes of off-site contamination from fly ash dumpsites. Vetiver (Vetiveria zizanioides) grown on fly ash for three months showed massive, mesh-like growth of roots which could have a phytostabilizing effect. The plant achieved this without any damage to its nuclear DNA as shown by comet assay done on the root nuclei, which implies the long-term survival of the plant on the remediation site. Also, when Vetiver is used for phytoremediation of coal fly ash, its shoots can be safely grazed by animals as very little of heavy metals in fly ash were found to be translocated to the shoots. These features make planting of Vetiver a practical and environmentally compatible method for restoration of fly ash dumpsites. Lack of DNA damage in Vetiver has been compared to that in a sensitive plant i.e. Allium cepa. Our results suggested that apart from traditional end-points viz. growth parameters like root length, shoot length and dry weight, comet assay could also be included in a battery of tests for initial, rapid and effective selection of plants for restoration and phytoremediation of polluted sites. PMID:21598787

Chakraborty, Rajarshi; Mukherjee, Anita

2011-02-01

258

Evaluation of selected Australian and overseas coals in boiler simulation test and improved ash fusion test  

Energy Technology Data Exchange (ETDEWEB)

A suite of selected coals that were previously studied in ACARP Project C3097 was investigated for the practical applicability of the Improved Ash Fusion Test (IAFT). The objective was to relate the results from the IAFT (which are provided as a continuous record of shrinkage against temperature) to plant performances from the combustion testing and if possible, existing ash fusion temperatures. The shrinkage traces have been explained in terms of events of liquid formation at the temperatures predicted by phase diagrams and are related to the ash chemistry. There is only very poor correlation between the Improved Ash Fusion Test results and the standard ash fusion test results. The extreme subjectivity of many of the standard ash fusion test results makes comparison meaningless. It is demonstrated that the standard ash fusion test results do not discriminate effectively between the ashes in this study, whereas the Improved Ash Fusion Test produces an evaluation that is equal to or perhaps better than the visual and tactile evaluation of the ash on the slagging panels in the Boiler Simulation Furnace. 7 refs., 7 figs., 8 tabs.

Kahraman, H.; Reifenstein, A.; Coin, C. [CSIRO, Kenmore, Qld. (Australia). Coal Geology Group

2000-10-01

259

Phosphorus adsorption and desorption in a sandy soil amended with high rates of coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

Amending sandy, drought-prone soils with high rates of coal fly ash has the potential to improve plant growth by enhancing soil moisture relations. However, some studies have questioned the plant availability of native and fertilizer phosphorus (P) in ash-amended soils. We used a batch adsorption study and a 42 day incubation study to examine the effects of amending an Evesboro loamy sand with fly ash (0-30%, w:w) on P availability and adsorption-desorption. Fly ash increased soil test P from 13 mg/kg (soil) to 34 mg/kg (30% ash) but had little effect on readily desorbable P. The adsorption or desorption of P was not markedly influenced by fly ash in either batch or incubation studies except at the highest ash and P rates. In the batch study, the greatest increases in P adsorption were seen at the 20% and 30% ash rates and P equilibrium concentrations {gt} 20 mg/L. Immediate and long-term decreases in P desorption occurred in the incubation study at all ash rates when greater than or equal to 500 mg P/kg were added but fly ash had little effect on P desorption at P rates less than or equal to 50 mg P/kg.

Oreilly, S.E.; Sims, J.T. [University of Delaware, Newark, DE (United States). Dept. of Plant and Soil Science

1995-12-31

260

Trace element characterization of coal fly ash particles  

International Nuclear Information System (INIS)

XRF, PIXE, RBS and STIM were used for a study of trace element distributions in Greek lignites and their ashes. Samples of fly ash collected from electrostatic precipitators have been separated into seven fractional sizes ranging from 300 ?m to less than 25 ?m. Trace element concentrations show variation as function of grain size. In addition, the results of analyses of 50 individual fly ash particles are presented. (orig.)

261

Surface chemical characteristics of coal fly ash particles after interaction with seawater under natural deep sea conditions  

International Nuclear Information System (INIS)

The surface chemical characteristics of coal fly ash (CFA) before and after interaction with Mediterranean deep seawater was studied by X-ray photoelectron spectroscopy (XPS). Significantly lower values of Si, Ca, and S and higher values of Mg and Cl were found in the retrieved CFA as compared to fresh CFA. It is suggested that hydrolysis of the oxide matrixes results in an alkaline environment which rapidly leads to several chemical reactions. The two most important are (a) dissolution of the amorphous silicate and the calcium phases and (b) precipitation of Mg(OH)2-brucite. A depth profile of the retrieved CFA was measured by both line-shape analysis of the XPS spectra and by consecutive cycle of sputtering. The thickness of the brucite layer is estimated to be 1.3 nm

262

Nano-mineralogical investigation of coal and fly ashes from coal-based captive power plant (India): An introduction of occupational health hazards  

International Nuclear Information System (INIS)

Coal derived nano-particles has been received much concern recently around the world for their adverse effects on human health and the environment during their utilization. In this investigation the mineral matter present in some industrially important Indian coals and their ash samples are addressed. Coal and fly ash samples from the coal-based captive power plant in Meghalaya (India) were collected for different characterization and nano-mineralogy studies. An integrated application of advanced characterization techniques such as X-ray diffraction (XRD), High Resolution-Transmission Electron microscopy (HR-TEM)/(Energy Dispersive Spectroscopy) EDS/(selected-area diffraction pattern) SAED, Field Emission-Scanning Electron Microscopy (FE-SEM)/EDS analysis, and Mössbauer spectroscopy were used to know their extent of risks to the human health when present in coal and fly ash. The study has revealed that the coals contain mainly clay minerals, whilst glass fragments, spinel, quartz, and other minerals in lesser quantities were found to be present in the coal fly ash. Fly ash carbons were present as chars. Indian coal fly ash also found to contain nanominerals and ultrafine particles. The coal-fired power plants are observed to be the largest anthropogenic source of Hg emitted to the atmosphere and expected to increase its production in near future years. The Multi Walled Carbon Nano-Tubes (MWCNTs) are detected in our fly ashes, which contains residual carbonaceous matter responsible for the Hg capture/encapsulation. This detailed investigation on the inter-relationship between the minerals present in the samples and their ash components will also be useful for fulfilling the clean coal technology principles. - Highlights: • We research changes in the level of ultrafine and nanoparticles about coal–ash quality. • Increasing dates will increase human health quality in this Indian coal area. • Welfare effects depend on ex-ante or ex-post assumptions about quality information

263

Nano-mineralogical investigation of coal and fly ashes from coal-based captive power plant (India): An introduction of occupational health hazards  

Energy Technology Data Exchange (ETDEWEB)

Coal derived nano-particles has been received much concern recently around the world for their adverse effects on human health and the environment during their utilization. In this investigation the mineral matter present in some industrially important Indian coals and their ash samples are addressed. Coal and fly ash samples from the coal-based captive power plant in Meghalaya (India) were collected for different characterization and nano-mineralogy studies. An integrated application of advanced characterization techniques such as X-ray diffraction (XRD), High Resolution-Transmission Electron microscopy (HR-TEM)/(Energy Dispersive Spectroscopy) EDS/(selected-area diffraction pattern) SAED, Field Emission-Scanning Electron Microscopy (FE-SEM)/EDS analysis, and Mössbauer spectroscopy were used to know their extent of risks to the human health when present in coal and fly ash. The study has revealed that the coals contain mainly clay minerals, whilst glass fragments, spinel, quartz, and other minerals in lesser quantities were found to be present in the coal fly ash. Fly ash carbons were present as chars. Indian coal fly ash also found to contain nanominerals and ultrafine particles. The coal-fired power plants are observed to be the largest anthropogenic source of Hg emitted to the atmosphere and expected to increase its production in near future years. The Multi Walled Carbon Nano-Tubes (MWCNTs) are detected in our fly ashes, which contains residual carbonaceous matter responsible for the Hg capture/encapsulation. This detailed investigation on the inter-relationship between the minerals present in the samples and their ash components will also be useful for fulfilling the clean coal technology principles. - Highlights: • We research changes in the level of ultrafine and nanoparticles about coal–ash quality. • Increasing dates will increase human health quality in this Indian coal area. • Welfare effects depend on ex-ante or ex-post assumptions about quality information.

Oliveira, Marcos L.S. [Laboratory of Environmental Researches and Nanotechnology Development, Centro Universitário La Salle, Mestrado em Avaliação de Impactos Ambientais em Mineração, Victor Barreto, 2288 Centro 92010-000, Canoas, RS (Brazil); Development Department of Touristic Opportunities, Catarinense Institute of Environmental Research and Human Development – IPADHC, Capivari de Baixo, Santa Catarina (Brazil); Marostega, Fabiane; Taffarel, Silvio R. [Laboratory of Environmental Researches and Nanotechnology Development, Centro Universitário La Salle, Mestrado em Avaliação de Impactos Ambientais em Mineração, Victor Barreto, 2288 Centro 92010-000, Canoas, RS (Brazil); Saikia, Binoy K. [Coal Chemistry Division, CSIR-North East Institute of Science and Technology, Jorhat 785006 (India); Waanders, Frans B. [School of Chemical and Minerals Engineering, North West University (Potchefstroom campus), Potchefstroom 2531 (South Africa); DaBoit, Kátia [Environmental Science and Nanotechnology Department, Institute of Environmental Research and Human Development – IPADHC, Capivari de Baixo, Santa Catarina (Brazil); Baruah, Bimala P. [Coal Chemistry Division, CSIR-North East Institute of Science and Technology, Jorhat 785006 (India); and others

2014-01-01

264

Opportunities and challenges in the use of coal fly ash for soil improvements--a review.  

Science.gov (United States)

Coal fly ash (CFA), a by-product of coal combustion has been regarded as a problematic solid waste, mainly due to its potentially toxic trace elements, PTEs (e.g. Cd, Cr, Ni, Pb) and organic compounds (e.g. PCBs, PAHs) content. However, CFA is a useful source of essential plant nutrients (e.g. Ca, Mg, K, P, S, B, Fe, Cu and Zn). Uncontrolled land disposal of CFA is likely to cause undesirable changes in soil conditions, including contamination with PTEs, PAHs and PCBs. Prudent CFA land application offers considerable opportunities, particularly for nutrient supplementation, pH correction and ameliorating soil physical conditions (soil compaction, water retention and drainage). Since CFA contains little or no N and organic carbon, and CFA-borne P is not readily plant available, a mixture of CFA and manure or sewage sludge (SS) is better suited than CFA alone. Additionally, land application of such a mixture can mitigate the mobility of SS-borne PTEs, which is known to increase following cessation of SS application. Research analysis further shows that application of alkaline CFA with or without other amendments can help remediate at least marginally metal contaminated soils by immobilisation of mobile metal forms. CFA land application with SS or other source of organic carbon, N and P can help effectively reclaim/restore mining-affected lands. Given the variability in the nature and composition of CFA (pH, macro- and micro-nutrients) and that of soil (pH, texture and fertility), the choice of CFA (acidic or alkaline and its application rate) needs to consider the properties and problems of the soil. CFA can also be used as a low cost sorbent for the removal of organic and inorganic contaminants from wastewater streams; the disposal of spent CFA however can pose further challenges. Problems in CFA use as a soil amendment occur when it results in undesirable change in soil pH, imbalance in nutrient supply, boron toxicity in plants, excess supply of sulphate and PTEs. These problems, however, are usually associated with excess or inappropriate CFA applications. The levels of PAHs and PCBs in CFA are generally low; their effects on soil biota, uptake by plants and soil persistence, however, need to be assessed. In spite of this, co-application of CFA with manure or SS to land enhances its effectiveness in soil improvements. PMID:25079682

Shaheen, Sabry M; Hooda, Peter S; Tsadilas, Christos D

2014-12-01

265

Trophic structure and metal bioaccumulation differences in multiple fish species exposed to coal ash-associated metals  

Energy Technology Data Exchange (ETDEWEB)

On December 22, 2008 a dike containing coal fly ash from the Tennessee Valley Authority Kingston Fossil Plant near Kingston Tennessee USA failed and resulted in the largest coal ash spill in U.S. history. Coal ash, the by-product of coal combustion, is known to contain multiple contaminants of concern, including arsenic and selenium. The purpose of this study was to investigate the bioaccumulation of arsenic and selenium and to identify possible differences in trophic dynamics in feral fish at various sites in the vicinity of the Kingston coal ash spill. Elevated levels of arsenic and selenium were observed in various tissues of largemouth bass, white crappie, bluegill and redear sunfish from sites associated with the Kingston coal ash spill. Highest concentrations of selenium were found in redear sunfish with liver concentrations as high as 24.83 mg/kg dry weight and ovary concentrations up to 10.40 mg/kg dry weight at coal ash-associated sites. To help explain the elevated selenium levels observed in redear sunfish, investigations into the gut pH and trophic dynamics of redear sunfish and bluegill were conducted which demonstrated a large difference in the gut physiology between these two species. Redear sunfish stomach and intestinal pH was found to be 1.1 and 0.16 pH units higher than in bluegill, respectively. In addition, fish from coal ash-associated sites showed enrichment of 15N & 13C compared to no ash sites, indicating differences in food web dynamics between sites. These results imply the incorporation of coal ash-associated compounds into local food webs and/or a shift in diet at ash sites compared to the no ash reference sites. Based on these results, further investigation into a broader food web at ash-associated sites is warranted.

Otter, Ryan [Middle Tennessee State University; Bailey, Frank [Middle Tennessee State University; Fortner, Allison M [ORNL; Adams, Marshall [ORNL

2012-01-01

266

Empirical prediction of ash deposition propensities in coal-fired utilities  

Energy Technology Data Exchange (ETDEWEB)

This report contain an outline of some of the ash chemistry indices utilized in the EPREDEPO (Empirical PREdiction of DEPOsition) PC-program, version 1.0 (DEPO10), developed by Flemming Frandsen, The CHEC Research Programme, at the Department of Chemical Engineering, Technical University of Denmark. DEPO10 is a 1st generation FTN77 Fortran PC-programme designed to empirically predict ash deposition propensities in coal-fired utility boilers. Expectational data (empirical basis) from an EPRI-sponsored survey of ash deposition experiences at coal-fired utility boilers, performed by Battelle, have been tested for use on Danish coal chemistry - boiler operational conditions, in this study. (au) 31 refs.

Frandsen, F.

1997-01-01

267

The valuation of trends flotability of non-burnt coal residuals /combustibe components from fly ash.  

Directory of Open Access Journals (Sweden)

Full Text Available Possibilities of the utilisation of energetical wastes in civil engineering applications is limited due to the content of residuals of non-burnt coal, magnetite iron, refined fly ash. The flotation is able to reduce the content of residuals of non-burnt coal in the ashes from coals. The optimum quantity of collector, required time of duration of the process, the number of purifying and control flotations, the percentage of combustible substances in all flotation products are very important flotation parameters. From the point of view of development of combustible components results of fly ashes flotation can be prezent in the flotation concentrate and in the waste after the flotation on the basis their mathematical trend models.

Benková Marta

2004-06-01

268

Elemental composition of coal fly ash: Malta coal power station in the Mpumalanga province in South Africa case study using nuclear and related analytical techniques  

International Nuclear Information System (INIS)

Epithermal neutron activation analysis along with ICP-OES, LA ICP-MS, and XRF were used to determine the elemental composition of coal fly ash from the Malta coal power station in the Mpumalanga province of South Africa. A total of 54 major, trace and rare-earth elements were obtained by the four analytical techniques. The results were compared and the discrepancies discussed to show the merits and drawbacks of each of the techniques. It was shown that the elemental content of this particular coal fly ash is of the same order as the NIST standard reference material Coal Fly Ash 1633b

269

Full-scale ash deposition measurements at Avedøre Power Plant unit 2 during suspension-firing of wood with and without coal ash addition.  

DEFF Research Database (Denmark)

The formation of deposits during suspension-firing of wood at Avedøre Power Plant unit 2 (AVV2) was studied by using an advanced deposit probe system. The tests were conducted both with and without coal ash addition, and at two different locations with flue gas temperatures of 1250-1300 oC and 750-800 oC respectively. The deposit formation process was studied quantitatively though the mass uptake data from the load-cell of the probe, while camera pictures were used to qualitatively verify the obtained mass uptake data and to explain the deposit buildup/shedding mechanisms. The collected deposits along with the fly ash and bottom ash from the plant were characterized extensively by SEM-EDS, ICP-OES/IC and XRD. Based on the results from the present work, the deposit formation and shedding mechanisms under different operational conditions were proposed and discussed. The influence of coal ash addition on deposit formation during wood suspension-firing at AVV2 was evaluated. It was revealed that the addition of coal fly ash could significantly influence the ash deposition/shedding behaviors and the deposit properties. The effect was evident at both measurement locations. At the location with a high flue gas temperature of 1250-1300 oC, although the addition of coal fly ash increased the differential deposit formation rate (DDF-rate) and the ash deposition propensity, the deposit removal frequency were considerably increased and the major shedding mechanism was changed from soot-blowing induced shedding to natural shedding. This implied that the deposits at high temperatures were more easily removable when coal ash was added. Besides, the amount of K2SO4 in the high-temperature deposits was considerably reduced when coal ash was added, which was probably favorable in order to minimize corrosion. At the location with a low flue gas temperature of 750-800 oC, the addition of coal fly ash reduced the ash deposition propensity and caused the formed deposits being easily removable. Moreover, the KCl and KOH/K2CO3 found in the low-temperature deposits without coal ash addition disappeared when coal ash was added, which was also favorable from a corrosion point of view.

Wu, Hao; Shafique Bashir, Muhammad

2012-01-01

270

Direct synthesis of carbon nanofibers from South African coal fly ash  

OpenAIRE

Carbon nanofibers (CNFs), cylindrical nanostructures containing graphene, were synthesized directly from South African fly ash (a waste product formed during the combustion of coal). The CNFs (as well as other carbonaceous materials like carbon nanotubes (CNTs)) were produced by the catalytic chemical vapour deposition method (CCVD) in the presence of acetylene gas at temperatures ranging from 400°C to 700°C. The fly ash and its carbonaceous products were characterized by transmission elect...

Hintsho, Nomso; Shaikjee, Ahmed; Masenda, Hilary; Naidoo, Deena; Billing, Dave; Franklyn, Paul; Durbach, Shane

2014-01-01

271

Iron speciation in coal fly ashes—chemical and Mössbauer analysis  

Science.gov (United States)

Iron speciation analysis of fly coal ashes was performed using transmision Mössbauer spectrometry as well as chemical methods. The investigated samples of ashes came from stoker-fired boiler and pulverized-fuel boiler (of significantly higher combustion temperature). The Mössbauer spectra show noticeable differences in iron-bearing phases content. In the first case aluminosilicate glass dominates, whereas in the second one—a spinel-type phase.

Szumiata, T.; Brzózka, K.; Górka, B.; Gawro?ski, M.; Gzik-Szumiata, M.; ?wietlik, R.; Trojanowska, M.

2014-04-01

272

Conceptual flow sheets development for coal conversion plant coal handling-preparation and ash/slag removal operations  

Energy Technology Data Exchange (ETDEWEB)

This report presents 14 conceptual flow sheets and major equipment lists for coal handling and preparation operations that could be required for future, commercial coal conversion plants. These flow sheets are based on converting 50,000 tons per day of clean coal representative of the Pittsburgh and Kentucky No. 9 coal seams. Flow sheets were used by Union Carbide Corporation, Oak Ridge National Laboratory, in a survey of coal handling/preparation equipment requirements for future coal conversion plants. Operations covered in this report include run-of-mine coal breaking, coarse coal cleaning, fine coal cleaning, live storage and blending, fine crushing (crushing to top sizes ranging from 1/4-inch to 20 mesh), drying, and grinding (70 percent minus 200 mesh). Two conceptual flow sheets and major equipment lists are also presented for handling ash or granulated slag and other solid wastes produced by nine leading coal conversion processes. These flow sheets provide for solid wastes transport to an environmentally acceptable disposal site as either dry solids or as a water slurry.

1979-07-01

273

Long-term prevention of organics dissolution from wastewater sludge treated with coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

This paper investigated the leaching behaviour of dissolved organic carbon (DOC) from sludge treated with coal fly ash as a hydraulic binder. Sludge from a biological wastewater treatment plant was dewatered in settling tanks dosed with flocculants and then centrifuged. Carbon black was used as an adsorbent of the organic substances. Sludge samples were mixed with carbon black and amended with coal fly ash. Twelve different samples were compacted into 100 cm{sup 3} polyethylene bottles and left for periods of 28 days, 1 year, and 2.5 years. Results indicated that DOC leachability was reduced by a factor of 10 when the sludge was mixed with 45 wt per cent coal fly ash and subjected to 28 days of hardening. Leachability of DOC was reduced by the addition of carbon black, but no more significant changes in DOC were observed with the addition of coal fly ash at 57 wt per cent. It was considered that the organic compounds from the sludge and inorganic compounds from the coal fly ash were simultaneously adsorbed by the carbon black. The extension of hardening time from 28 days to 1 year brought about higher DOC values because of the conversion of organic compounds to soluble organic compounds of lower molecular weight. The hardening period of 2.5 years led to DOC values that were close to the DOC value after only 1 year of hardening time. It was concluded that the treated sludge was stabilized in the matrix of hydrated coal fly ash within 1 year. X-ray diffraction and scattered electron microscopy analyses confirmed the formation of calcium silicate hydrate in the treated sludge. 21 refs., 3 tabs., 5 figs.

Kuchar, D.; Onyango, M.S.; Matsuda, H. [Nagoya Univ., Nagoya (Japan). Dept. of Chemical Engineering; Bednarik, V.; Vondruska, M. [Tomas Bata Univ., Zlin (Czech Republic). Dept. of Environmental Technology and Chemistry; Kojima, Y. [Nagoya Univ., Nagoya (Japan). Ecotopia Inst.

2006-09-15

274

Levels and patterns of polycyclic aromatic hydrocarbons in coal-fired power plant bottom ash and fly ash from Huainan, China.  

Science.gov (United States)

Fly ash and bottom ash samples were collected from a coal-fired power plant located in Anhui province, China. Mineral phases and morphologies of the samples were determined by X-ray diffraction and scanning electron microscopy, respectively. Sixteen polycyclic aromatic hydrocarbon (PAH; 16 compounds specified in United States Environmental Protection Agency Method 610) properties in ash samples were investigated. In fly ashes, ?16PAH (total amount of 16 PAHs) and ?CPAH (total amount of 8 carcinogenic PAHs) levels varied from 0.93 to 2.08 ?g/g and from 0.26 to 0.87 ?g/g, respectively. In bottom ashes, ?16PAH and ?CPAH levels varied from 2.83 to 5.32 and 1.76 to 3.76 ?g/g, respectively. Fly ashes were dominated by medium molecular-weight PAHs and low molecular-weight PAHs, whereas bottom ashes were abundant in 5- and 6-ring PAH species. The CPAHs levels of some ashes, especially bottom ashes, are greater than the limits regulated by several countries, indicating that this type of coal combustion product requires special treatment before landfill. PAH levels and patterns in fly ash were evidently affected by particle size, and total organic content had a closer correlation with PAH content than particle size in bottom and fly ash, which may be due to unburned carbon existing in bottom ash. PMID:23591765

Ruwei, Wang; Jiamei, Zhang; Jingjing, Liu; Liu, Guijian

2013-08-01

275

Sample collection and preparation methods affecting mutagenicity and cytotoxicity of coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

Reports by several investigators describing the biological activity of coal fly ash have presented a variety of results which in some cases are conflicting. The biological activity of coal fly ash may differ because of one or more of the following factors: (1) the samples studied were from different sources; (2) the samples were prepared for bioassay differently; (3) the sampling method differed, and, therefore, collected samples were different in chemical or physical properties which affect the biological activity. Several variables involved in coal fly ash studies -- source, sample collection land preparation methods, bioassay method -- are undoubtedly responsible for the diversity of biological effects observed. The objectives of this study were to examine the sample preparation and collection factors which may affect the observed biological activity caused by coal fly ash and to evaluate the mutagenicity and cytotoxicity of fluidized-bed combustion (FBC) fly ash from experimental and commercial units. The bioassays used in this study were the Ames Salmonella plate incorporation test for mutagenicity and the rabbit alveolar macrophage (RAM) system for cytotoxicity.

Mumford, J.; Lewtas, J.

1983-07-01

276

Thermal properties of insulating material prepared from coal fly ash and asphalt  

International Nuclear Information System (INIS)

Coal power plants are producing ash in enormous quantity as fly ash and bottom ash, whenever coal is combusted. Lakhra Coal Power Plant produces waste of solid fossil fuel and lime stone. Due to the silica, alumina and iron oxide it is good to be used in cement preparation and land filling. In this study a new application is identified, which is more useful and beneficial. This paper presents the results carried out investigating the insulating material prepared from the coal fly ash and asphalt by using the simple unit operations of sizing the materials. At melting temperature of the asphalt sieved fly ash is mixed with it to produce complex heavy sludge. Two samples of different ratios from the rapidly solidifying insulating material were prepared in the molding press at 200 psi pressure. Arm-field heat conduction apparatus HT-l was applied to test its thermal properties. Thermal properties of the material were observed to be heat resistant with mean thermal conductivity at 10 watt 0.8949 w/m-K for Sample No.1 and 0.91886 w/m-K for Sample No.2; whereas the mean thermal resistances calculated were 30.4 I 65m/sup 2/-K/w and 29.6234m/sup 2/-K/w, respectively. The results obtained during this study are satisfactory and we hope that the insulation material prepared would be used in Pakistan in building constructions for heat resistance and insulation purposes. (author)

277

The use of coal fines fly ash for the improvement of soils in hydrophobic grounds  

International Nuclear Information System (INIS)

New NOx reducing combustion techniques result in a different physical and morphological quality of fly ash, which makes the use of fly ash less attractive for the building and road construction industries. Attention is paid to the possibility of using low-NOx fly ash for the improvement of the properties of hydrophobic agricultural land. Such an application also depends on the environmental impacts of the leaching of elements to the ground water and the accumulation of hazardous compounds in crops. A literature study of hydrophobic grounds was carried out. Also attention is paid to the legal aspects. No juridical constraints could be found in the Dutch legislation concerning the use of fly ash from coal powder, although it seems that the use of such fly ash is not in agreement with the tenor of possibly to be applied legislation. However, a small-scale investigation was carried out to gain insight into the environmental impacts. The uptake in lettuce and the leaching of the elements As, B, Mo and Se was studied by means of lysimeters. Hydrophobic soils with 5%, 10% and 15% coal fines fly ash were used. Also an experiment with the use of coal gasification slags was performed

278

Ecological risk assessment for residual coal fly ash at Watts Bar Reservoir, Tennessee.  

Science.gov (United States)

The Tennessee Valley Authority conducted a Baseline Ecological Risk Assessment (BERA) for the Kingston Fossil Plant ash release site to evaluate potential effects of residual coal ash on biota in Watts Bar Reservoir, Tennessee. The BERA was in response to a release of 4.1 million m(3) of coal ash on December 22, 2008. It used multiple lines of evidence to assess risks for 17 different ecological receptors to approximately 400000?m(3) of residual ash in the Emory and Clinch rivers. Here, we provide a brief overview of the BERA results and then focus on how the results were used to help shape risk management decisions. Those decisions included selecting monitored natural recovery for remediation of the residual ash in the Emory and Clinch rivers and designing a long-term monitoring plan that includes adaptive management principles for timely adjustment to changing conditions. This study demonstrates the importance of site-specific ecological data (e.g., tissue concentrations for food items, reproductive data, and population data) in complex ecological risk assessments. It also illustrates the value of the US Environmental Protection Agency's (USEPA) data quality objectives process in building consensus and identifying multiple uses of results. The relatively limited adverse effects of this likely worst-case scenario for ash-related exposures in a lotic environment provide important context for the USEPA's new coal combustion residue disposal rules. PMID:25346032

Carriker, Neil E; Jones, Daniel S; Walls, Suzanne J; Stojak, Amber R

2015-01-01

279

Sequestration of carbon dioxide by indirect mineralization using Victorian brown coal fly ash  

International Nuclear Information System (INIS)

Highlights: ? The indirect CO2 mineralization by brown coal fly ash has been tested. ? A large CO2 capture capacity of fly ash under mild conditions was achieved. ? The kinetic analysis confirmed a fast reaction rate with low activation energy. ? The fly ash based capture process is highly efficient and cost-effective. - Abstract: The use of an industry waste, brown coal fly ash collected from the Latrobe Valley, Victoria, Australia, has been tested for the post-combustion CO2 capture through indirect minersalization in acetic acid leachate. Upon the initial leaching, the majority of calcium and magnesium in fly ash were dissolved into solution, the carbonation potential of which was investigated subsequently through the use of a continuously stirred high-pressure autoclave reactor and the characterization of carbonation precipitates by various facilities. A large CO2 capture capacity of fly ash under mild conditions has been confirmed. The CO2 was fixed in both carbonate precipitates and water-soluble bicarbonate, and the conversion between these two species was achievable at approximately 60 °C and a CO2 partial pressure above 3 bar. The kinetic analysis confirmed a fast reaction rate for the carbonation of the brown coal ash-derived leachate at a global activation energy of 12.7 kJ/mol. It is much lower than that for natural minerals and is also very close to the potassium carbonate/piperazi the potassium carbonate/piperazine system. The CO2 capture capacity of this system has also proven to reach maximum 264 kg CO2/tonne fly ash which is comparable to the natural minerals tested in the literature. As the fly ash is a valueless waste and requires no comminution prior to use, the technology developed here is highly efficient and energy-saving, the resulting carbonate products of which are invaluable for the use as additive to cement and in the paper and pulp industry.

280

Analysis of natural radionuclides in coal, slag and ash in coal-fired power plants in Serbia  

Directory of Open Access Journals (Sweden)

Full Text Available The radioactivity monitoring in the “Nikola Tesla”, “Kolubara”, “Morava” and “Kostolac” coal-fired power plants was performed by the Radiation and Environmental Protection Laboratory, Vin?a Institute of nuclear sciences in the period 2003-2010. Monitoring included the analysis of soil, water, flying ash, slag, coal and plants. This paper presents the results of the radioactivity analysis of coal, ash and slag samples. Naturally occurring radionuclides 226Ra, 232Th, 40K, 235U, 238U, and 210Pb as well as the man-made radionuclide 137Cs were determined by gamma spectrometry using HPGe detector. The concentrations of pairs of radionuclides were statistically tested to determine the correlation between them. Based on the obtained results, health effect due to the activity of these radionuclides was estimated via radium equivalent (Raeq, external hazard index (Hex, external gamma absorbed dose rate ( and annual effective dose.

Jankovi? M.M.

2011-01-01

281

Determination of the carbon content in coal and ash by XRF  

Energy Technology Data Exchange (ETDEWEB)

Carbon in coal and ash samples was determined by wavelength-dispersive x-ray fluorescence (WDXRF). A rhodium side-window tube was used for C K alpha excitation and a synthetic multilayer crystal for excited radiation analysis. The samples, undiluted or diluted with boric acid, were pressed as layers of 0.16 g cm{sup -2} thickness on to a boric acid support. The relative standard deviation was 1.8, 1.5 and 15% for undiluted, diluted coal and ash, respectively.

Parus, J.; Kierzek, J.; Malozewska-Bucko, B. [Institute of Nuclear Chemistry and Technology, Warsaw (Poland)

2000-04-01

282

Nuclear techniques for analysis of coal for calorific value, ash and moisture  

International Nuclear Information System (INIS)

This bibliography includes references on nuclear techniques for analysis of coal for calorific value, ash and moisture content. As the search was directed particularly towards measurement of the ash content of coal using x- and gamma-ray methods, references covering only ?-ray techniques have been placed in a separate section. References from Chemical Abstracts prior vol.62 (1965) do not cite the language of the original article. The language of the original has been given for all other articles not in English. (author)

283

Utilization of zeolites synthesized from coal ash for methylene blue removal from water  

Directory of Open Access Journals (Sweden)

Full Text Available The adsorption of methylene blue from aqueous solution was carried out using zeolites synthesized from coal ash as low-cost adsorbents. The coal ash sample was converted to zeolites by hydrothermal treatment using different synthesis parameters. The materials were characterized by physical-chemical analysis, XRD and SEM studies. The adsorption isotherms can be fitted by Freundlich model. The values of the adsorption capacity of adsorbents were similar for adsorbents. Kinetic studies indicate that the adsorption follows pseudo-second-order kinetic model.

Denise Alves Fungaro

2008-12-01

284

Carbon-Enriched coal fly ash as a precursor of activated carbons for SO2 Removal  

OpenAIRE

Carbon-enriched coal fly ash was evaluated in this work as a low-cost adsorbent for SO2 removal from stack gases. The unburned carbon in coal fly ash was concentrated by mechanical sieving and vegetal oil agglomeration. The carbon concentrates were activated with steam at 900ºC in order to develop porosity onto the samples. The performance of these samples in the SO2 abatement was tested in the following conditions: 100ºC, 1000 ppmv SO2, 5% O2, 6% water vapor. A good SO2 remo...

Izquierdo Pantoja, Mari?a Teresa; Rubio Villa, Begon?a

2007-01-01

285

Trace elements and their mobility in coal ash/fly ash from Indian power plants in view of its disposal and bulk use in agriculture  

Energy Technology Data Exchange (ETDEWEB)

Coal and power production currently generate approximately 75 Mt of coal combustion waste in India annually. It is expected that this amount will reach 290 Mt by 2011-2012. The use of this waste product is currently negligible at 2 to 6 per cent. Fly ash disposal facilities in India are fly ash-slurry surface ponds with open water circuits. The greatest potential for use of the fly ash would be in the construction sector for building materials such as bricks, tiles and cements or in the agricultural sector as a soil amendment and fertilizer. The latter is the most attractive to India, therefore the content and mobility of trace elements in fly ash from Indian power plants are of major importance. This study analyzed trace element mobility. Examples were presented of field studies involving ground water quality in wells in the vicinity of a fly ash slurry pond under operation and on trace element uptake from fly ash-amended soils. The paper also presented the characteristics of coal ash from Indian power plants and the trace element concentrations in well water affected by FA leachate. It was concluded that fly ash disposal in surface ponds is not environmentally safe, and agricultural use of the waste product appears to be a prospective sink for fly ash. It was suggested that more studies on the long-term environmental behaviour of fly ash should be conducted. 2 refs., 1 tab.

Twardowska, I. [Polish Academy of Science, Inst. of Environmental Engineering, Zabrze (Poland); Tripathi, P.S.M. [Central Fuel Research Inst., Bihar (India); Das, R.P. [Central Fuel Research Inst., Orissa (India). Regional Research Laboratory

2001-07-01

286

Valorization of coal fly ash by mechano-chemical activation Part I. Enhancing adsorption capacity  

Energy Technology Data Exchange (ETDEWEB)

The adsorption characteristics of coal fly ash have been enhanced by mechano-chemical activation with a high energy mono-planetary ball mill. The best performing sample for the adsorption of phenol from aqueous solution (i.e., fly ash with the higher carbon content and mechano-chemically activated for 4 h in N{sub 2} atmosphere) was compared with powdered activated carbon, yielding quite encouraging results such as favorable adsorption isotherms, improved specific adsorption capacity and very fast adsorption rate. This provides new opportunities for utilizing fly ash in environmental protection applications like the stabilization/solidification treatment of hazardous waste and contaminated soil.

Stellacci, P.; Liberti, L.; Notarnicola, M.; Bishop, P.L. [Technical University of Bari, Taranto (Italy). Dept. of Environmental Engineering & Sustainable Development

2009-07-15

287

Coal Fly Ash Ceramics: Preparation, Characterization, and Use in the Hydrolysis of Sucrose  

Science.gov (United States)

Coal ash is a byproduct of mineral coal combustion in thermal power plants. This residue is responsible for many environmental problems because it pollutes soil, water, and air. Thus, it is important to find ways to reuse it. In this study, coal fly ash, obtained from the Presidente Médici Thermal Power Plant, was utilized in the preparation of ceramic supports for the immobilization of the enzyme invertase and subsequent hydrolysis of sucrose. Coal fly ash supports were prepared at several compaction pressures (63.66–318.30?MPa) and sintered at 1200°C for 4?h. Mineralogical composition (by X-ray diffraction) and surface area were studied. The ceramic prepared with 318.30?MPa presented the highest surface area (35?m2/g) and amount of immobilized enzyme per g of support (76.6?mg/g). In assays involving sucrose inversion, it showed a high degree of hydrolysis (around 81%) even after nine reuses and 30 days' storage. Therefore, coal fly ash ceramics were demonstrated to be a promising biotechnological alternative as an immobilization support for the hydrolysis of sucrose. PMID:25110726

dos Santos, Ricardo Pires; Martins, Jorge; Gadelha, Carlos; Cavada, Benildo; Albertini, Alessandro Victor; Arruda, Francisco; Vasconcelos, Mayron; Teixeira, Edson; Alves, Francisca; Lima Filho, José; Freire, Valder

2014-01-01

288

Determination of ash content of coal using nuclear borehole logging spectrometric gamma-gamma technique  

International Nuclear Information System (INIS)

During the past decade, increasing effort has been given to monitoring coal quality in the search, production and preparation sequence. Considerable research and development has been carried out on nuclear methods for determination of ash in coal. A number of nuclear techniques are now well established for coal analysis. In particular, the spectrometric gamma-gamma technique is based on the existence of a simple correlation between the ash content and the equivalent atomic number of coal. This technique records and uses the count rates of the backscatter spectrum. These count rates describe the changes in spectral shape which are due to ash content variations. This method is presented along with a short review of the physical background. The report includes the simulation of in situ borehole probe readings using a MONTE CARLO tracking program. Simulating the transport through matter of gamma-rays by MONTE CARLO techniques essentially attempts to reproduce the actual statistical nature of the interaction processes. Random numbers are used throughout, along with known nuclear data, to select the parameters which influence a particle's history. Such an approach can deal with complex geometries through which the particles move. Biaising or weightening techniques are applied for variance reduction, so as to minimise the statistical errors. The basic features of biaising as well as the description of the program are given. A semi-theoretical approach is discussed for the determination of ash content of coal seam using the simulated spectrum

289

Clearance by the rat of inhaled fly ash from fluidized-bed coal combustion  

International Nuclear Information System (INIS)

Fly ash from a fluidized-bed coal combustor was neutron-activated and administered to male Fischer 344 rats by a single nose-only inhalation exposure. The activated fly ash contained 46Sc and smaller amounts of other gamma-emitting radionuclides. Whole-body clearance of radioactivity of 127 d was described by an exponential equation, with the long-term component having a biological half-life of 78 d. High-resolution gamma spectra of the lungs was obtained with a Ge(Li) detector and the relative activities of several fly ash constituents were compared. The activities of 152Eu, 134Cs, 54Mn, and 60Co significantly decreased with time relative to those of 46Sc and 59Fe. These results indicate that the clearance of fly ash is similar to that of other relatively insoluble particles and that some elements may have been preferentially dissolved from the fly ash particles in vivo

290

Characterization of a flying ash stemming from the combustion of the coal  

Science.gov (United States)

In this study, we were interested in the physic - chemical characterization (SEM, BET, X-ray, DTA-TG, and IR) of the flying ashes stemming of the combustion of the coal in the thermal power station of JORF-LASFAR in EL Jadida (Morocco). On the one hand, we deduce from this study that these flying ashes are belonging to the class F Fly ash (according to ASTM standards). The X-ray diffraction shows that the ashes are mainly constituted by the aluminosilicate and the quartz. The thermal analysis (DTA-TG), the IR, and SEM proves the presence of the carbonates of the calcium. On the other hand, after washing the ashes, with the distilled water, an equilibrium of adsorption - desorption of the carbonates was reached after 30 minutes.

Moufti, A.; Brahmi, R.; Garmes, H.; Bensitel, M.; Mountadar, M.

2005-03-01

291

Characterization of a flying ash stemming from the combustion of the coal  

Energy Technology Data Exchange (ETDEWEB)

In this study, we were interested in the physicochemical characterization (SEM, BET, X-ray, DTA-TG, and IR) of the fly ash stemming from the combustion of the coal in the thermal power station of JORF-LASFAR in EL Jadida (Morocco). On the one hand, we deduce from this study that the fly ash belong to the class F Fly ash (according to ASTM standards). The X-ray diffraction shows that the ashes are mainly constituted by the aluminosilicate and the quartz. The thermal analysis (DTA-TG), the IR, and SEM proves the presence of calcium carbonates. On the other hand, after washing the ashes, with distilled water, an equilibrium of adsorption - desorption of the carbonates was reached after 30 minutes.

Moufti, A.; Brahmi, R.; Garmes, H.; Bensitel, M.; Mountadar, M.

2005-03-01

292

Effect of mixes made of coal bottom ash and fly ash on the mechanical strength and porosity of Portland cement  

Directory of Open Access Journals (Sweden)

Full Text Available New additions to the cement are needed to achieve a more sustainable and durable construction material. Within this context, bottom ashes can be used as a main constituent of Portland cements when it is mixed in an optimized proportion with fly ashes. The mechanical characteristics of standarized mortars made of mixes of pulverized coal combustion bottom and fly ashes are studied. The mortars were made of ordinary Portland cement (CEM I 42.5 N and mixes of bottom ashes with fly ashes in similar proportions to those of CEM II/A-V, CEM II/B-V and CEM IV/A (V. Summing up, it can be said that the utilization of bottom ashes mixed with fly ashes in replacement levels from 0% to 100% do not affect significantively on the mechanical caracteristics of the mortars considered in the present study which had an addition maximum content of 35%.

La utilización de nuevas adiciones en el cemento es necesaria con el fin de obtener un material más sostenible y durable. En este sentido, las cenizas de fondo o cenicero de las centrales termoeléctricas de carbón se podrían reciclar siendo empleadas como un componente principal de los cementos Portland. Se han estudiado las propiedades mecánicas de unos morteros normalizados elaborados con mezclas de cenizas volantes con cenizas de fondo fabricados con unos porcentajes similares a los correspondientes de los CEM II/A-V, CEM II/B-V y CEM IV/A (V. En conclusión, la utilización de mezclas de cenizas de fondo o cenicero con cenizas volantes sustituyendo a éstas últimas entre el 0% y el 100%, no influye significativamente en el comportamiento mecánico de los morteros estudiados en los que el contenido máximo de adición ha sido del 35%, si bien afecta a determinados aspectos microestructurales, como la cantidad y distribución de poros capilares.

Argiz, C.

2013-03-01

293

An Evaluation on the Physical and Chemical Composition of Coal Combustion Ash and Its Co-Placement with Coal-Mine Waste Rock  

OpenAIRE

In the last few decades, the utilization of coal to generate electricity was rapidly increasing. Consequently, the production of coal combustion ash (CCA) as a by-product of coal utilization as primary energy sources was increased. The physical and geochemical characteristics of CCA were site-specific which determined by both inherent coal-source quality and combustion condition. This study was intended to characterize the physical, chemical and mineralogical properties of a coal-combustion a...

Budi Sulistianto; Gautama, Rudy S.; Candra Nugraha; Kikuo Matsui; Hideki Shimada; Takashi Sasaoka; Kusuma, Ginting J.

2012-01-01

294

Concentrations and distributions of trace and minor elements in Chinese and Canadian coals and ashes  

International Nuclear Information System (INIS)

A total of 35 trace and minor elements including some of environmental significance were determined in each of a selection of 15 Chinese and 6 Canadian thermal coals and their ashes by using the SLOWPOKE-2 nuclear reactor facility of the University of Toronto. The concentrations and distributions of these constituents among the coals and their combustion products (viz. ash and volatile matter) are presented. The detailed results showed wide variations in trace impurity concentrations (up to a factor of 100 and more) among the coals studied. Values for elemental enrichment factors (EF) relative to normal crustal abundances indicated that only As(EF=13), Br(5.7), I(16), S(230), Sb(11) and Se(320) were appreciably enriched in coal. (author) 14 refs.; 5 tabs

295

RECLAMATION OF ALKALINE ASH PILES AND PROTECTION OF THEIR ENVIRONMENT AGAINST DUSTING  

Science.gov (United States)

The objective of this study was to develop methods to reclaim and stabilize by vegetation fly ash and bottom ash from bituminous and lignite fired power plants. The ash had been transported from the power plant as a slurry and disposed of in ponds. Ashes from these power plants w...

296

Effects of coal fly ash on tree swallow reproduction in Watts Bar Reservoir, Tennessee.  

Science.gov (United States)

Coal-fly ash was released in unprecedented amounts (4.1?×?10(6) m(3) ) into the Emory River from the Tennessee Valley Authority Kingston Fossil Plant on Watts Bar Reservoir in Tennessee. Tree swallows were exposed to ash-related constituents at the ash release via their diet of emergent aquatic insects, whose larval forms can accumulate constituents from submerged river sediments. Reproduction of tree swallow colonies was assessed over a 2-year period by evaluating whether 1) ash constituent concentrations were elevated in egg, eggshell, and nestling tissues at colonies near ash-impacted river reaches compared to reference colonies, 2) production of fledglings per nesting female was significantly lower in ash-impacted colonies versus reference colonies, and 3) ash constituent concentrations or diet concentrations were correlated with nest productivity measures (clutch size, hatching success, and nestling survival, and fledglings produced per nest). Of the 26 ash constituents evaluated, 4 (Se, Sr, Cu, and Hg) were significantly elevated in tissues potentially from the ash, and 3 (Se, Sr, and Cu) in tissues or in swallow diet items were weakly correlated to at least one nest-productivity measure or egg weight. Tree swallow hatching success was significantly reduced by 12%, but fledgling production per nest was unaffected due to larger clutch sizes in the impacted than reference colonies. Bioconcentration from the ash to insects in the diet to tree swallow eggs appears to be low. Overall, adverse impacts of the ash on tree swallow reproduction were not observed, but monitoring is continuing to further ensure Se from the residual ash does not adversely affect tree swallow reproduction over time. Integr Environ Assess Manag 2015;11:56-66. © 2014 SETAC. PMID:25345977

Walls, Suzanne J; Meyer, Carolyn B; Iannuzzi, Jacqueline; Schlekat, Tamar H

2015-01-01

297

Experimental investigation of ash behavior and emissions during combustion of Bosnian coal and biomass  

International Nuclear Information System (INIS)

This paper presents results of experimental research into the ash behavior of different Bosnian coal types and biomass fired in an electrically heated entrained pulverized fuel flow experimental reactor. The results are derived from a series of tests performed under a range of temperature and air conditions for the fuel test matrix. In essence, the experimental reactor comprises a 3 m length alumina-silicate ceramic tube, where combustion takes place, surrounded by SiC stick-type electric heaters and three-layer insulation. The temperature of the reaction zone is controlled by a programmable logic controller (PLC) with thyristor units for each of the heating zones, allowing the process temperature to be varied at will across the range from ambient to 1560 oC. The methodology is based on the evaluation of ash deposits formed in the experimental reactor during the tests. Test points, reflecting the different types of ash deposits, are plotted against appropriate fuel indicators onto graphic diagrams. Emissions of NO x and SO2 are also measured under different ambient conditions-at different temperatures and air distributions-to determine the emission figures for the fuels being tested. The results for six different fuels are presented, namely two single coals, two coal blends, and two coal-biomass blends. The results obtained support the thesis that the appropriate ambient conditions for combustion of coals and biomass can be recognized on of coals and biomass can be recognized and recorded in this way

298

Suspension-firing of wood with coal ash addition: Probe measurements of ash deposit build-up at Avedøre Power Plant (AVV2)  

DEFF Research Database (Denmark)

This report is about full-scale probe measurements of deposit build-up and removal conducted at the Avedøreværket Unit 2, a 800 MWth suspension boiler, firing wood and natural gas with the addition of coal ash. Coal ash was used as an additive to capture potassium (K) from wood-firing. Investigations of deposit formation rate were made by use of an advanced online ash deposition/shedding probe. Quantification of ash deposition and shedding was made via deposit mass uptake signals obtained from the deposit probe. The influence of coal ash, flue gas temperature, probe surface temperature and boiler load on ash deposition propensity was investigated. Results of ash deposition propensity showed increasing trend with increasing flue gas temperature. Video monitoring revealed that the deposits formed were not sticky and could be easily removed, and even at very high flue gas temperatures (> 1350 oC), deposit removal through surface melting was not identified. SEM-EDS analysis of the deposits showed significant presence of Ca, Al and Si, indicating that a significant amount of K has been captured by coal ash to form deposits rich in calcium-aluminum-silicates, and possible release of Cl to the gas phase as HCl(g). Effect of boiler operational parameters on gas emissions has also been investigated.

Shafique Bashir, Muhammad; Jensen, Peter Arendt

2012-01-01

299

Impact of coal fly ash addition on ash transformation and deposition in a full-scale wood suspension-firing boiler  

DEFF Research Database (Denmark)

Ash transformation and deposition during pulverized wood combustion in a full-scale power plant boiler of 800 MWth were studied with and without the addition of coal fly ash. The transient ash deposition behavior was characterized by using an advanced deposit probe system at two boiler locations with flue gas temperatures of about 1300 C and 800 C, respectively. The mechanisms of ash transformation and deposit formation were elaborated through a detailed characterization of the collected deposits and fly ashes. The results implied that during pulverized wood combustion, the formation of deposits at the location with high flue gas temperatures was characterized by a slow and continuous growth of deposits followed by the shedding of a large layer of deposits, while at the location with low flue gas temperature the deposit formation started with a slow build-up and the amount of deposits became almost constant after a few hours. The formed deposits, especially those at the location with low flue gas temperatures, contained a considerable amount of K2SO4, KCl, and KOH/K2CO3. With the addition of a large amount (about 4 times of the mass flow of wood ash) of coal fly ash to the boiler, these alkali species were effectively removed both in the fly ash and in the deposits. Although the ash deposition rate at the location with high flue gas temperature was increased with coal fly ash addition, the removability of the deposits was significantly improved, resulting in a more frequent shedding of the deposits. Overall, the results from this work suggest that coal fly ash can be an effective additive to minimize the possible ash deposition and corrosion problems during suspension-firing of wood. © 2013 Elsevier Ltd. All rights reserved.

Wu, Hao; Bashir, Muhammad Shafique

2013-01-01

300

Radiological significance of coal, slag and fly ash samples from the Eastern Black Sea region  

Energy Technology Data Exchange (ETDEWEB)

This work presents a study of natural radioactivity levels in coal and its combustion residues (fly ash and slag) used in the houses in Black Sea Region, Turkey. Coal, fly ash and slag samples were provided from different locations of the region and analyzed by gamma spectroscopy using a high-purity germanium detector (HPGe). Also, chemical analyses of these samples were carried out using energy dispersive X-ray fluorescence spectrometer. The mean {sup 226}Ra activity concentrations in coal, slag and fly ash were measured as 83, 99 and 38 Bq kg{sup -1}, respectively. The mean {sup 232}Th activity concentrations in coal, slag and fly ash were measured as 108, 113 and 50 Bq kg{sup -1}, respectively. The mean {sup 40}K activity concentrations in coal, slag and fly ash were found to be 366, 381 and 204 Bq kg{sup -1}, respectively. The potential radiological hazards associated to these materials were evaluated by calculating the radium equivalent activity (Ra{sub eq}), the air absorbed gamma dose rate (D), the annual effective dose rate (AED), the external hazard index (H{sub ex}) and internal hazard index (H{sub in}) and compared with the internationally accepted or reference values. The mean Ra{sub eq} values of the coal, fly ash and slag samples were lower than the recommended maximum values 370 Bq kg{sup -1} by the Organization for Economic Cooperation and Development (OECD). The overall mean outdoor terrestrial gamma air absorbed dose rate in coal, fly ash and slag samples are 119, 129 and 62 nGy h{sup -1} and the corresponding outdoor annual effective doses are 0.60, 0.32 and 0.64 mSv y{sup -1}, which is higher than the worldwide average (0.07 mSv y{sup -1}), respectively. Moreover, the enrichment factors relative to the input coal are calculated for the radionuclide contents observed. Calculated enrichment factor values for {sup 226}Ra and {sup 232}Th were found 1.14 and 1.01, respectively. (orig.)

Damla, Nevzat [Batman Univ. (Turkey). Dept. of Physics; Cevik, Ugur [Karadeniz Technical Univ., Trabzon (Turkey). Dept. of Physics; Kara, Ayhan [Osmaniye Korkut Ata Univ. (Turkey). Dept. of Physics

2012-11-15

301

A novel silica alumina-based backfill material composed of coal refuse and fly ash.  

Science.gov (United States)

In this paper, a systematic study was conducted to investigate a novel silica alumina-based backfill material composed of coal refuse and fly ash. The coal refuse and fly ash had different properties under various thermal activation temperatures (20 °C, 150 °C, 350 °C, 550 °C, 750 °C and 950 °C). It is known that a thermal activation temperature ranging from 20 °C to 950 °C significantly increases the flowability and pozzolanic properties of the coal refuse; however, the flowability of fly ash decreases when the activation temperature is higher than 550 °C because of a severe agglomeration phenomenon on its surface. An optimal design for this backfill material was determined to include an activated portion composed of 5% coal refuse at 750 °C and 15% fly ash at 20 °C. This combination yields the best performance with excellent flowability, a high compressive strength and a low bleeding rate. The microanalysis results corresponded well with the performance tests at different activation conditions. In the coal refuse, kaolinite peaks began to decrease because of their transformation into metakaolin at 550 °C. Chlorite peaks disappeared at 750 °C. Muscovite peaks decreased at 750 °C and disappeared at 950 °C. During this process, muscovite 2M(1) gradually dehydroxylated to muscovite HT. Furthermore, this paper examined the environmental acceptance and economic feasibility of this technology and found that this silica alumina-based backfill material composed of coal refuse and fly ash not only meets EPA requirements but also has several advantages in industry feasibility when compared with hydraulic backfill, rock backfill and paste backfill. PMID:22336582

Yao, Yuan; Sun, Henghu

2012-04-30

302

Integrated production/use of ultra low-ash coal, premium liquids and clean char. Technical report, September 1, 1991--November 30, 1991  

Energy Technology Data Exchange (ETDEWEB)

This integrated, multi-product approach for utilizing Illinois coal starts with the production of ultra low-ash coal and then converts it to high-vale, coal-derived, products. The ultra low-ash coal is produced by solubilizing coal in a phenolic solvent under ChemCoal{trademark} process conditions, separating the coal solution from insoluble ash, and then precipitating the clean coal by dilution of the solvent with methanol. Two major products, liquids and low-ash char, are then produced by mild gasification of the low-ash coal. The low ash-char is further upgraded to activated char, and/or an oxidized activated char which has catalytic properties. Characterization of products at each stage is part of this project.

Kruse, C.W.

1991-12-31

303

Feasibility of fly ash-based composite coagulant for coal washing wastewater treatment  

International Nuclear Information System (INIS)

Highlights: ? Coal washing wastewater was analyzed. ? Several fly ash-based composite coagulants were prepared to treat coal washing wastewater. ? The effluent with the high COD and SS removal was obtained after treatment. - Abstract: In this study, several fly ash (FA)-based composite coagulants, leached by hydrochloric acid, were prepared to treat coal washing wastewater. The concentrations of Al3+ and Fe2+/Fe3+ in the leachates and coagulants were analyzed, and optimal experimental conditions, including coagulant dosage and initial pH, were determined using various analytical techniques (scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction (XRD), X-ray fluorescence (XRF), particle-size analysis, zeta potential, pH and conductivity measurements). A suspended solids (SS) and chemical oxygen demand (COD) removal efficiency from the effluent treated by one of the coagulants reached 99.61% and 96.48%, respectively, at dosages of 10 g l?1 (initial pH of 9, adjusted by CaO). This indicates that the coagulant was an effective agent for coal washing wastewater treatment, and that the leached Al3+ and Fe3+ and introduced Ca2+ may have improved the coagulation process. Analysis of the dry sludge composition and slurry particle size distribution of the coal washing wastewater showed that charged colloidal particles and the fine particle distribution in the coal washicle distribution in the coal washing wastewater make the wastewater treatment a difficult process. Results from this study could provide a novel approach for the treatment of coal washing wastewater and coal fly ash utilization.

304

The accumulation of boron on Agropyron elongatum grown in coal fly ash and sewage sludge mixture  

International Nuclear Information System (INIS)

A greenhouse pot experiment was conducted to investigate the boron (B) release capacity of coal fly ash and sewage sludge mixtures, and the accumulation of B in tall wheat grass (Agropyron elongatum) after two consecutive growing seasons. Sludge was amended with fly ash at application rates of 0, 5, 10, 35 and 50% (w/w), and each mixture was then mixed with a loamy soil at either 1:1 or 1:5 (v/v). Both water soluble B (WS-B) and hot water soluble B (HWS-B) increased with increasing fly ash amendment rate. Shoot B concentrations also increased significantly according to the rate of ash amendment. The ash-sludge mixture improved plant growth with the highest total dry weight yield at 10% ash amendment rate. Boron toxicity symptoms in leaf tips were observed at 35% and 50% ash amendment rate at both soil mixing ratios. Hot water soluble B and WS-B decreased significantly after consecutive cropping of (Agropyron) especially at low ratio of mixture with soil i.e., 1:5 (v/v). However, soil available B contents at > 35% ash application rate and 1:1 (v/v) soil mixing ratio were still excessive for normal plant growth, suggesting that deleterious effects on plant growth would be experienced in later seasons owing to the high amounts of residual B. 18 refs., 4 figs., 3 tabs

305

Trace element toxicity in VA mycorrhizal cucumber grown on weathered coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

Mycorrhizal colonization is widely recognized as enhancing plant growth on severely disturbed sites. A greenhouse pot experiment was conducted to determine if inoculation with vesicular-arbuscular mycorrhizal (VAM) fungi will enhance vegetation establishment on abandoned coal fly ash basinss, Spores of Glomus intraradices (Schenck and Smith) and Glomus etunicatum (Becker and Gerdemann) were added to weathered precipitator ash (EC-0.91 dSm[sup -1], pH 5.0) and to a pasteurized soils of the same pH (Grossarenic Paleudult, 92% sand, 1% organic matter). Some soil and ash were left unamended as non-mycorrhizal controls. Cucumber (Cucumis sativus L. cv. Poinsette 76) seeds were sown, watered regularly, and fertilized periodically with macronutrient solution. By 8 weeks all ash-grown plants exhibited smaller leaves with leaf margin curl and necrosis, and plant biomass was significantly less (0.75x) than soil-grown plants. Based on analysis of 18 elements in plant tissues, toxicity to B, Mn, or Zn could have caused growth suppression, confirming trace element problems for plant growth on fly ash. For plants grown on fly ash, G. etunicatum was the only fungus that colonized roots (20% of root length reduced from 67% on soil) and it suppressed plant growth to 0.80 x that of uninoculated ash-grown plants. Correspondingly, shoot Zn concentration in G. etunicatum-inoculated plants was 3.5 x higher than in uninoculated plants and at generally toxic levels (273 mg kg[sup -1]). Glomus etunicatum had no other significant effects on elemental concentrations. These results indicate that VAM colonization in acid, weathered fly ash suppressed plant growth by facilitating uptake of Zn to toxic levels, and implies a limitation to successful use of VAM for vegetation establishment on abandoned coal fly ash basins.

Dosskey, M.G.; Adriano, D.C. (University of Georgia, Aiken, SC (United States). Savannah River Ecology Lab.)

1993-11-01

306

Cobalt(II) removal from synthetic wastewater by adsorption on South African coal fly ash  

Scientific Electronic Library Online (English)

Full Text Available Advanced wastewater-treatment techniques such as adsorption are essential in the removal of non-biodegradable toxic wastes from water. In this study, the use of South African coal fly ash, an industrial byproduct, has been investigated as a potential replacement for the current costly adsorbents use [...] d for removing heavy metals from wastewater. We utilised coal fly ash for the adsorption of cobalt(II) ions from synthetic petrochemical wastewater and characterised its performance. A two-level three-factor full-factorial design was successfully employed for experimental design and analysis of the results. The combined effects of pH, initial concentration and adsorbent dose on cobalt(II) removal were assessed using response surface methodology. Although the focus was on removal of cobalt(II), the adsorption was carried out in the presence of phenol and other heavy metal ions using the batch technique. The applicability of the Freundlich and Langmuir models to the equilibrium data was tested. Consequently, the equilibrium data was found to conform more favourably to the Freundlich isotherm than to the Langmuir isotherm; in this case, the coal fly ash had a maximum adsorption capacity of 0.401 mg/g for cobalt(II). We conclude that South African coal fly ash, as a natural, abundant and low-cost adsorbent, might be a suitable local alternative for elimination of cobalt(II) from aqueous solutions.

Evans T., Musapatika; Maurice S., Onyango; Ochieng, Aoyi.

2010-10-01

307

The nuclear methods of analysis of ecological exploitation properties of coals and ashes  

International Nuclear Information System (INIS)

The application of nuclear methods for determination of ecological and exploitation properties of different kinds of coals and ashes has been discussed. It has been confirmed experimentally the usefulness of x-ray fluorescence analysis for elementary composition, Moessbauer spectroscopy for phase contribution and gamma spectroscopy for radioactive nuclides determination in samples of natural materials. 7 refs, 5 tabs

308

Radon induced radiological impact of coal, fly ash and cement samples  

International Nuclear Information System (INIS)

Coal and its by-product fly ash are technologically important materials being used for power generation and in the manufacture of bricks, sheets, cement, land-filling, etc., respectively. Increased interest in measuring radon concentration in coal, fly ash and cement is due to its health hazards and environmental pollution. As the presence of radon in the environment (indoor and outdoor), soil, ground water, oil and gas deposits contributes the largest fraction of the natural radiation dose to populations, tracking its concentration is thus of paramount importance for radiological protection. Samples of coal and fly ash were collected from different thermal power stations in northern India and cement samples from National Council for Cement and Building Materials, Ballabgarh (Haryana), India and were analysed for radon concentration. For the measurement, alpha sensitive LR-115 type II plastic track detectors were used. Based upon the available data, the annual effective dose and the lifetime fatality risk factors have been calculated. The radon concentration from coal samples varied from 433 ± 28 Bqm-3 to 2086 ± 28 Bqm-3. The radon concentration from fly ash samples varied from 748 ± 28 Bqm-3 to 1417 ± 111 Bqm-3 and from 158 Bqm-3 to 1810 Bqm-3 in cement samples, with an average of 624 ± 169 Bqm-3. (author)

309

Ash chemistry aspects of straw and coal-straw co-firing in utility boilers  

Energy Technology Data Exchange (ETDEWEB)

Deposits formed in straw-fired grate-boilers showed significant amounts of KCl ( 40 - 80 % (w/w)) and KCl-coated Ca-Si-rich particles. CFB co-firing of straw and coal caused deposits in the convective pass containing predominantly K{sub 2}SO{sub 4} (50 - 60 % (w/w)) with small amounts of KCl close to the metal surface. In pulverized coal-straw co-fired boilers, deposits almost free of KCl were found. Most of the potassium in these deposits is derived from K-Al-Si-rich fly ash particles and the rest occurs as K{sub 2}SO{sub 4}. The presence of K-Al-Si-rich fly ash particles indicates that solid residue quality and reuse of fly ash in cement and concrete production rather than deposit formation may be of concern when utilizing straw in pulverized fuel boilers. This paper provides a review of Danish experiences with high-temperature ash deposit formation in the following full-scale utility boilers: Slagelse CHP (31 MW{sub th}), Haslev CHP (23 MW{sub th}) and Rudkoebing CHP (10.7 MW{sub th}), all straw-fired grate-boilers; Grenaa CHP (80 MW{sub th}), a coal-straw co-fired Circulating Fluidized Bed (CFB) boiler; and the Midtkraft-Studstrup Power Station, Unit l (380 MW{sub th}), a coal-straw co-fired pf-boiler. (au)

Frandsen, F.; Nielsen, H.P.; Hansen, L.A.; Hansen, P.F.B.; Andersen, K.H.; Soerensen, H.S.

1998-12-01

310

Ash chemistry aspects of straw and coal-straw co-firing in utility boilers  

Energy Technology Data Exchange (ETDEWEB)

Deposits formed in straw-fired grate-boilers showed significant amounts of KCl (40--80% (w/w)) and KCl-coated Ca-Si-rich particles. CFB co-firing of straw and coal caused deposits in the convective pass containing predominantly K{sub 2}SO{sub 4} (50--60% (w/w)) with small amounts of KCl close to the metal surface. In pulverized coal-straw co-fired boilers, deposits almost free of KCl were found. Most of the potassium in these deposits is derived from K-Al-Si-rich fly ash particles and the rest occurs as K{sub 2}SO{sub 4}. The presence of K-Al-Si-rich fly ash particles indicates that solid residue quality and reuse of fly ash in cement and concrete production rather than deposit formation may be of concern when utilizing straw in pulverized fuel boilers. This paper provides a review of Danish experiences with high-temperature ash deposit formation in the following full-scale utility boilers: Slagelse CHP (31 MWth), Haslev CHP (23 MWth) and Rudkoebing CHP (10.7 MWth), all straw-fired grate-boilers; Grenaa CHP (80 MWth), a coal-straw co-fired Circulating Fluidized Bed (CFB) boiler; and the Midtkraft-Studstrup Power Station, Unit 1 (380 MWth), a coal-straw co-fired PF-boiler.

Frandsen, F.J.; Nielsen, H.P.; Hansen, L.A. [Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Chemical Engineering; Hansen, P.F.B.; Andersen, K.H. [Midtkraft I/S Power Co., Skoedstrup (Denmark). Studstrup Power Station; Soerensen, H.S. [Geological Survey of Denmark and Greenland, Copenhagen (Denmark)

1998-12-31

311

DESIGN AND CHARACTERIZATION OF AN ULTRAFINE COAL ASH AEROSOL GENERATOR FOR DIRECT ANIMAL EXPOSURE STUDIES  

Science.gov (United States)

Primary ultrafine particulate matter (PM) is produced during pulverized coal combustion by the nucleation and heterogeneous condensation of vapor-phase species. This differs from the mechanisms that control the formation of the supermicron fly ash that is heavily influenced by t...

312

Biological assessment of a coal-ash contaminated stream using pleurocerid snails  

International Nuclear Information System (INIS)

To assess the biological impacts of coal-ash on a stream community, a mark-release-recapture study was conducted with two pleurocerid snails, Elimia sp. and Pleurocera sp. Seven hundred snails of each species were collected from a reference stream, tagged, weighed, and released into a snail-free, coal-ash contaminated stream (McCoy Branch) in eastern Tennessee. Snails were also caged in the stream for one week; all remained alive. Four weeks after the release, only 14% of each species were recovered; all were downstream from the release point. Recovered Pleurocera had higher ammonium excretion rates than those in the reference stream. Growth rates were negligible. Recovered snails were re-released into McCoy Branch and recovered again four weeks later. Less than 2% of the total snails were recovered; again, all downstream. Both species had extremely low ammonium excretion rates possibly because of a depletion of protein reserves, but respiration rates were similar to those in a reference stream. The recovered snails had little or no growth and new shell growth was thin and brittle. These results suggest the snails were experiencing physiological stress. Laboratory experiments are now in progress to test two hypotheses: (1) physiological effects of stress in Pleurocera resulted from exposure to coal-ash contaminated sediment, and (2) selenium and arsenic, contaminants concentrated in coal-ash, contributed to these effects

313

Assessment of ecotoxicological risks of element leaching from pulvarized coal ashes.  

OpenAIRE

This thesis describes the consequences of the disposal of the combustion residues of coal, especially the uptake of elements from such residues and their effects on various organisms. The effects on benthic organisms in fresh and in seawater are considered in the first two parts. The third part looks at the uptake of elements from coal residues and their effect on the growth of plants and worms.The central theme is the combustion residue known as pulverized fuel ash (PFA), or 'flyash'. Coal i...

Jenner, H. A.

1995-01-01

314

Sulfur retention by ash during coal combustion. Part I. A model of char particle combustion  

Directory of Open Access Journals (Sweden)

Full Text Available A model for the combustion of porous char particles as a basis for modeling the process of sulfur retention by ash during coal combustion is developed in this paper. The model belongs to the microscopic intrinsic models and describes the dynamic behavior of a porous char particle during comustion, taking into account temporal and spatial changes of all important physical properties of the char particle and various combustion parameters. The parametric analysis of the enhanced model shows that the model represents a good basis for the development of a model for the process of sulfur retention by ash during coal combustion. The model enables the prediction of the values of all parameters necessary for the introduction of reactions between sulfur compounds and mineral components in ash, primarily calcium oxide.

BORISLAV GRUBOR

2003-02-01

315

Fly ash from Texas lignite and western subbituminous coal: a comparative characterization  

Energy Technology Data Exchange (ETDEWEB)

As examples, we use two Jackson group lignites from Atascosa and Fayette Counties, Texas, and a Green River Region subbituminous coal from Routt County, Colorado. The composition of individual fly ash particles was determined using scanning electron microscopy and electron microprobe, with support from x-ray diffraction of bulk ash. Using particle sample populations large enough to permit statistical treatment, we describe the relationship of composition to particle size and the correlation between elemental concentrations, as well as particle size and composition distributions. Correlations are displayed as data maps which show the complete range of observed variation among these parameters, emphasizing the importance of coal variability. We next use this data to produce a population distribution of ash particle resistivities calculated with Bickelhaupt's model. The relationship between calculated resistivity and particle size is also displayed, and the results are compared with measured values. 7 figures.

Sears, D. R.; Benson, S. A.; McCollor, D. P.; Miller, S. J.

1982-01-01

316

Natural radioactivity in the surrounding soil and fly ash from coal fired thermal power plant  

International Nuclear Information System (INIS)

In India about 70% of the total power generation originates from thermal power plants. The coal fired power generation results in huge amounts of fly with elevated levels of naturally occurring radionuclides. Despite the implementation of best possible mechanisms to restrict release of fly ash from the stack, a huge amount of the same gets released in the environment. Fly ash and soil from and around a 500 MW capacity coal-fired power station were measured for 238U, 226Ra, 232Th and 40K activity by an HPGe ?-ray spectrometer. The surrounding soil showed no elevated levels of the radionuclides however higher levels were observed for the same in the fly ash. (author)

317

Sulfur-bearing coatings on fly ash from a coal-fired power plant: Composition, origin, and influence on ash alteration  

Science.gov (United States)

Fly ash samples collected from two locations in the exhaust stream of a coal-fired power plant differ markedly with respect to the abundance of thin (???0.1 ??m) sulfur-rich surface coatings that are observable by scanning electron microscopy. The coatings, tentatively identified as an aluminum-potassium-sulfate phase, probably form upon reaction between condensed sulfuric acid aerosols and glass surfaces, and are preferentially concentrated on ash exposed to exhaust stream gases for longer. The coatings are highly soluble and if sufficiently abundant, can impart an acidic pH to solutions initially in contact with ash. These observations suggest that proposals for ash use and predictions of ash behavior during disposal should consider the transient, acid-generating potential of some ash fractions and the possible effects on initial ash leachability and alteration. ?? 1998 Elsevier Science Ltd.

Fishman, N.S.; Rice, C.A.; Breit, G.N.; Johnson, R.D.

1999-01-01

318

Influence of Chemical Composition on the Electrical Resistivity of Fly Ash Generated from Indian Coal Based Thermal Power Plants  

Directory of Open Access Journals (Sweden)

Full Text Available Electrostatic Precipitators (ESP are control devices widely used for collection of fly ash in Indian coal based thermal power plants. The design, performance, sizing, collection and operation of ESP depend largely on the properties and quality of the coal burned and the fly ash generated in the boilers. This study presents the influence of fly ash composition on the resistivity of Indian fly ash generated from coal based power plants, which is one of the critical parameter required to make accurate predictions of ESP in terms of their collection efficiency. The fly ash electrical resistivity measurements were conducted over a wide range of temperature in both ascending and descending cycles in the range of 90 to 455ºC at 9% moisture as per IEEE-Standard 548 (1991. The earlier developed Empirical relations used for calculating fly ash electrical resistivity for western coals were modified for the calculations of electrical resistivity of Indian fly ashes and new empirical relations have been developed based on experimental results and chemical composition of fly ash samples collected from different coal based power plants in India which have different chemical composition in comparison to western coals. Results in the newly developed correlations show better agreements with experimentally determined resistivity compared to those developed by Bickelhaupt and others

Syed Javid Ahmad Andrabi

2013-02-01

319

ECONOMICS OF NITROGEN OXIDES, SULFUR OXIDES, AND ASH CONTROL SYSTEMS FOR COAL-FIRED UTILITY POWER PLANTS  

Science.gov (United States)

The report gives results of an EPA-sponsored economic evaluation of three processes to reduce NOx, SO2, and ash emissions from coal-fired utility power plants: one based on 3.5% sulfur eastern bituminous coal; and the other, on 0.7% sulfur western subbituminous coal. NOx control ...

320

Exploring evaluation to influence the quality of pulverized coal fly ash. Co-firing of biomass in a pulverized coal plant or mixing of biomass ashes with pulverized coal fly ash; Verkennende evaluatie kwaliteitsbeinvloeding poederkoolvliegas. Bijstoken van biomassa in een poederkoolcentrale of bijmenging van biomassa-assen met poederkoolvliegas  

Energy Technology Data Exchange (ETDEWEB)

In this literature survey the consequences of co-firing of biomass and mixing of biomass ash with coal fly ash on the coal fly ash quality is evaluated. Biomass ash considered in this context is produced by gasification, pyrolysis or combustion in a fluidized bed. The irregular shape of biomass ash obtained from gasification, pyrolysis or combustion has a negative influence on the water demand in concrete applications of the coal fly ash resulting from mixing biomass ash and coal fly ash. In case of co-firing, high concentrations of elements capable of lowering the ash melting point (e.g., Ca and Mg) may lead to more ash agglomeration. This leads to a less favourable particle size distribution of the coal fly ash, which has a negative impact on the water demand in cement bound applications. Gasification, pyrolysis and combustion may lead to significant unburnt carbon levels (>10%). The unburnt carbon generally absorbs water and thus has a negative influence on the water demand in cement-bound applications. The contribution of biomass ash to the composition of coal fly ash will not be significantly different, whether the biomass is co-fired or whether the biomass ash is mixed off-line with coal fly ash. The limit values for Cl, SO4 and soluble salts can form a limitation for the use of coal fly ash containing biomass for cement-bound applications. As side effects of biomass co-firing, the level of constituents such as Na, K, Ca and Mg may lead to slagging and fouling of the boiler. In addition, a higher emission of flue gas contaminants As, Hg, F, Cl and Br may be anticipated in case more contaminated biomass streams are applied. This may also lead to a higher contamination level of gypsum produced from flue gas cleaning residues. Relatively clean biomass streams (clean wood, cacao shells, etc.) will hardly lead to critical levels of elements from a leaching point of view. More contaminated streams, such as sewage sludge, used and preserved wood, petcoke and RDF (refuse derived fuels), will most likely lead to increased leaching. This will be more prominent for oxyanions than for metals. In the evaluation of the application of coal fly ash in cement production or in partial cement replacement, it is important to assess the materials behaviour in recycling stages in unbound form besides its leaching behaviour of the intact product in its service life. This aspect has not been addressed before. If a material performs poorly from an environmental point of view in its recycling stages, one should be more critical in allowing (too) high levels of co-firing or too high mixing ratios of biomass. In general, the oxyanions will be more critical than most metals. The variability in several types of biomass is rather high. This holds limitations for plant operation and availability. Premixing of biomass during size reduction leads to more consistent input and thus to more constant ash quality. Co-firing may lead to increased Cr-VI levels in the fly ash due to oxidation of Cr, which is more prominently present in flue gas upon biomass co-firing than in case of regular coal firing. Elevated Cr-VI levels are more leachable. The following recommendations have been made: measurement of leaching behaviour of coal fly ash from co-firing of different biomass streams with a special emphasis on Cr-VI leachability; measurement of flue gas quality relative to pure coal combustion during co-firing of contaminated biomass streams; verification of durability of cement-based products containing coal fly ash with ash from biomass; evaluation of the leaching behaviour of recycling products from the primary uses of biomass ash or fly ash. 35 refs.

Van der Sloot, H.A.; Cnubben, P.A.J.P [ECN Schoon Fossiel, Petten (Netherlands)

2000-08-01

321

Melting Behavior of ashes from the co-combustion of coal and straw  

DEFF Research Database (Denmark)

Straw may be used today as a substitute fuel to lower the greenhouse gas emissions from traditional coalfired power plants and provide green-based electricity. It may also provide an alternative source of income to the local farmers helping the developed countries to support sustainable development. The use of straw as a co-firing feedstock in traditional coal-fired plants is associated with operational problems, such as deposition, agglomeration, and/or corrosion, mainly because of the higher amounts of alkali metals and chlorine in straw compared to coal. This may lead to unscheduled shutdowns and costly repairs, increasing the operational costs and the cost of the produced power. In this paper, the melting characteristics of several ash fractions sampled from different parts of a pilot-scale pulverized fuel (PF) boiler operating with different coal/straw mixtures is determined by measuring the ash viscosity using a high-temperature rotational viscometer. The produced data provide information on the meltingof the ash material, its flow characteristics, and the rates of crystallization and recrystallization, as a function of the temperature. This information may be used to modify the temperature profile in the different parts of the boiler to reduce the deposition of the ash material. The results show that the straw in the co-combustion mixture changes the viscosity characteristics of the produced ash fractions. The viscosity of the different ash fractions is lowered, as the percentage of straw in the cocombustion mixture increases, and leads to higher stickiness of the produced ash particles at lower temperatures.

Arvelakis, Stelios; Frandsen, Flemming

2007-01-01

322

Use of coal ash in production of concrete containing contaminated sand  

International Nuclear Information System (INIS)

There are between 2 to 3.5 million underground storage tanks located throughout the nation. Most of these tanks, which store oils and gasolines, are leaking making them one of the primary sources of soil contamination. Adding coal ash or cement to contaminated soil has been used to obtain stationary and inert wastecrete. By using this procedure, stabilization (limiting the solubility and mobility of the contaminants) and solidification (producing a solid waste block) of contaminated soils are successfully achieved. This paper investigates another re-use option of coal ash and contaminated soils. An experimental study evaluating the effectiveness of using coal ash with oil contaminated sand in concrete production is presented. A control mix made of clean sand was designed to yield 500 psi of compressive strength. Sand, artificially contaminated with 3% by weight of motor oil, was used as clean sand replacement. Six concrete mixtures were tested in compression and flexure. The six mixtures were obtained by increasing the ratio of contaminated sand to clean sand, namely; 10%, 20% and 40% and by introducing coal ash to the concrete mixture, namely; 20% of the cement weight. The test results indicate that the inclusion of oil contaminated sand in concrete reduces the compressive and flexural strengths. However, this decrease in strength is compensated by introducing coal ash in the mixture. Regaining that strength offers the possibility of using such concrete as a construcility of using such concrete as a construction material in special structural applications. More research is required to establish better understanding of that composite and suggest feasible applications

323

Preparation of sintered foam materials by alkali-activated coal fly ash.  

Science.gov (United States)

Coal fly ash from coal fired power stations is a potential raw material for the production of ceramic tiles, bricks and blocks. Previous works have demonstrated that coal fly ash consists mainly of glassy spheres that are relatively resistant to reaction. An objective of this research was to investigate the effect of alkali on the preparation process of the foam material. Moreover, the influence of foam dosage on the water absorption, apparent density and compressive strength was evaluated. The experimental results showed that homogenous microstructures of interconnected pores could be obtained by adding 13 wt.% foaming agent at 1050 degrees C, leading to foams presenting water absorption, apparent density and compressive strength values of about 126.5%, 0.414 g/cm(3), 6.76 MPa, respectively. PMID:19775812

Zhao, Yelong; Ye, Junwei; Lu, Xiaobin; Liu, Mangang; Lin, Yuan; Gong, Weitao; Ning, Guiling

2010-02-15

324

Study of radon exhalation rate in some soil, coal and fly ash samples using SSNTD technique  

International Nuclear Information System (INIS)

The exhalation rate of radon from different materials were measured using CR-39 solid state nuclear track detectors (SSNTDs). The radon exhalation rate varies from 52 to 117 mBq.m-2h-1 in soil samples, from 50 to 73 mBq.m-2h-1 in coal samples and from 78 to 96 mBq.m-2h-1 in fly ash samples, respectively. In two soil samples, the radon exhalation rate is higher than the fly ash samples. This may be due to the low emanation power of fly ash, as the radionuclide contents of fly ash are found to be higher than the soil by various investigations. (author)

325

Effects of coal fly ash-amended composts on the yield and elemental uptake by plants  

International Nuclear Information System (INIS)

The objective of this study was to determine the feasibility of coal fly ash-amended composts for use as an alternate manure for agricultural crops. Home-made organic composts was mixed in various proportions with fine fly ash collected from Savannah River Site, and allowed to decompose for two weeks while the mixture was kept wet. Water extracts from the amended composts were analyzed for selected major and trace elements. These amended composts were mixed with sifted sandy loam soil in a predetermined optimum ratio of 1:3 and used to grow corn and sorghum plants. It was shown that fly ash additions to home-made compost facilitated efficient plant utilization of nutrients when 20-40% fly ash in compost was applied to the soil. The maximum dry shoot yields correlated with the higher concentrations of K, Ca and N and lower concentrations of B in the amended compost treatment

326

Effects of coal fly ash-amended composts on the yield and elemental uptake by plants  

Energy Technology Data Exchange (ETDEWEB)

The objective of this study was to determine the feasibility of coal fly ash-amended composts for use as an alternate manure for agricultural crops. Home-made organic composts was mixed in various proportions with fine fly ash collected from Savannah River Site, and allowed to decompose for two weeks while the mixture was kept wet. Water extracts from the amended composts were analyzed for selected major and trace elements. These amended composts were mixed with sifted sandy loam soil in a predetermined optimum ratio of 1:3 and used to grow corn and sorghum plants. It was shown that fly ash additions to home-made compost facilitated efficient plant utilization of nutrients when 20-40% fly ash in compost was applied to the soil. The maximum dry shoot yields correlated with the higher concentrations of K, Ca and N and lower concentrations of B in the amended compost treatment.

Menon, M.P.; Ghuman, G.S.; James, J.; Chandra, K. (Savannah State Coll., GA (United States))

1992-01-01

327

Predicting Water Quality Problems Associated with Coal Fly Ash Disposal Facilities Using a Trace Element Partitioning Study  

Science.gov (United States)

For much of the U.S., coal-fired power plants are the most important source of electricity for domestic and industrial use. Large quantities of fly ash and other coal combustion by-products are produced every year, the majority of which is impounded in lagoons and landfills located throughout the country. Many older fly ash disposal facilities are unlined and have been closed for decades. Fly ash often contains high concentrations of toxic trace elements such as arsenic, boron, chromium, molybdenum, nickel, selenium, lead, strontium and vanadium. Trace elements present in coal fly ash are of potential concern due to their toxicity, high mobility in the environment and low drinking water MCL values. Concern about the potential release of these toxic elements into the environment due to leaching of fly ash by acid rain, groundwater or acid mine drainage has prompted the EPA to develop national standards under the subtitle D of the Resource Conservation and Recovery Act (RCRA) to regulate ash disposal in landfills and surface impoundments. An attempt is made to predict the leaching of toxic elements into the environment by studying trace element partitioning in coal fly ash. A seven step sequential chemical extraction procedure (SCEP) modified from Filgueiras et al. (2002) is used to determine the trace element partitioning in seven coal fly ash samples collected directly from electric power plants. Five fly ash samples were derived from Eastern Bituminous coal, one derived from Western Sub-bituminous coal and the other derived from Northern Lignite. The sequential chemical extraction procedure gives valuable information on the association of trace elements: 1) soluble fraction, 2) exchangeable fraction, 3) acid soluble fraction, 4) easily reducible fraction, 5) moderately reducible fraction, 6) poorly reducible fraction and 7) oxidizable organics/sulfide fraction. The trace element partitioning varies with the composition of coal fly ash which is influenced by the type of coal burned. Preliminary studies show that in some fly ash samples, significant amounts of As, B, Mo, Se, Sr and V are associated with the soluble and exchangeable fraction, and thus would be highly mobile in the environment. Lead, on the other hand, is mainly associated with the amorphous Fe and Mn oxide fractions and would be highly immobile in oxidizing conditions, but mobile in reducing conditions. Ni and Cr show different associations in different fly ash samples. In most fly ash samples, significant amounts of the trace elements are associated with more stable fractions that do not threaten the environment. The study of trace element partitioning in coal fly ash thus helps us to predict their leaching behavior under various conditions.

Bhattacharyya, S.; Donahoe, R. J.; Graham, E. Y.

2006-12-01

328

The Ash Probe - A new instrument for the in-situ measurement of the ash content of coal piles. From development to commercial exploitation  

International Nuclear Information System (INIS)

In this short paper we have provided a brief description of how the Ash Probe was developed from a germ of an idea through to a commercial instrument with international appeal. The results of field tests described above have shown that good calibrations can be achieved and under strict conditions the ash content of a coal pile can be tested within a few minutes to an accuracy of better than 0.5% ash. Feedback from our first customer, Consolidated Coal, reveals that over the course of one year the Ash Probe has worked reliably with only one small fault - a cracked LCD display. It has not required re-calibration and accuracy to within 1% ash has invariably been achieved. (orig./UKE)

329

Uranium trace and alpha activity characterization of coal and fly ash using particle track etch technique  

International Nuclear Information System (INIS)

Uranium is extensively found in carbonaceous components of sedimentary rocks and is considered to be accumulated in coals during the coalification process through the geological times. Burning of coal is mainly responsible for a manifold increase in the concentration of radioactive nuclides in atmosphere precipitates. Fly ash being an incombustible residue and formed from 90% of the inorganic material in coal, escapes into the atmosphere and constitutes a potential hazard. Also its use as one of the pozzolanic materials in the products of concrete, bricks etc and filling of ground cavities is even more hazardous because of the wall radioactivity, besides emission and diffusion of radon. This paper reports a simple method called Particle Track Etch (PTE) technique, for trace determination of uranium content in coal and fly ash samples by making use of low cost and versatile plastic detectors known as Solid State Nuclear Track Detectors (SSNTDs). Total alpha activity has also been estimated using these SSNTDs. The values of uranium concentration in coal samples are found to range from 1.1 to 3.6 ppm (uniform component) and 33 to 46 ppm (non-uniform part) whereas in fly ash, it varies from 8 to 11 ppm (uniform) and 55 to 71 ppm in non-uniform range. It is also observed that the alpha activity is a function of uranium concentration for most of the natural samples of coal studied except for mixtures of fly ash samples where relationship is found to be on higher side. (authnship is found to be on higher side. (author). 13 refs., 2 tabs., 1 fig

330

Pulmonary effects of ultrafine coal fly ash inhaled by guinea pigs  

Energy Technology Data Exchange (ETDEWEB)

Guinea pigs were exposed to ultrafine coal fly ash produced in a laboratory furnace. The average mass median aerodynamic diameter and the average mass concentration of Illinois no. 6 fly ash produced in all exposure conditions were 0.21 {mu}m and 5.8 mg/m{sup 3}, respectively. In guinea pigs exposed to Illinois no. 6 fly ash, total lung capacity (TLC), vital capacity (VC), and diffusing capacity for carbon monoxide (DLco) were significantly reduced below the control values immediately, 2 h, and 8 h postexposure. The diffusing capacity was still 10% below the control 96 h after exposure. The total sulfate in the Illinois no. 6 fly ash as determined using ion chromatography is 1105 {plus minus} 120 {mu}g/m{sup 3}. Animals exposed to the Montana lignite fly ash at comparable concentration and particle size did not show alteration in diffusing capacity. The data suggest that part of the sulfate present in the fly ash of Illinois no. 6 could be in the form of sulfuric acid and is responsible for the adverse effects observed in the exposed animals. The sulfuric acid in the fly ash of Montana lignite is neutralized by its high alkali content and produces no change in lung functions. 26 refs., 7 figs.

Lung Chi Chen; Hua Fuan Lam; Kim, E.J.; Guty, J.; Amdur, M.O. (Massachusetts Inst. of Tech., Cambridge, MA (USA). Dept. of Applied Biological Sciences and Energy Lab.)

1990-01-01

331

Investigation of Fly Ash and Activated Carbon Obtained from Pulverized Coal Boilers  

Energy Technology Data Exchange (ETDEWEB)

One of the techniques for Hg capture in coal-fired boilers involves injection of activated carbon (AC) into the boiler downstream of the air preheater. Hg is adsorbed onto the AC particles and fly ash, which are then both removed in an electrostatic precipitator or baghouse. This project addressed the issues of Hg on activated carbon and on fly ash from a materials re-use point of view. It also addressed the possible connection between SCR reactors, fly ash properties and Hg capture. The project has determined the feasibility of separating AC from fly ash in a fluidized bed and of regenerating the separated AC by heating the AC to elevated temperatures in a fluidized bed. The temperatures needed to drive off the Hg from the ash in a fluidized bed have also been determined. Finally, samples of fly ash from power plants with SCR reactors for NO{sub x} control have been analyzed in an effort to determine the effects of SCR on the ash.

Edward K. Levy; Christopher Kiely; Zheng Yao

2006-08-31

332

Regeneratively cooled coal combustor/gasifier with integral dry ash removal  

Science.gov (United States)

A coal combustor/gasifier is disclosed which produces a low or medium combustion gas for further combustion in modified oil or gas fired furnaces or boilers. Two concentric shells define a combustion volume within the inner shell and a plenum between them through which combustion air flows to provide regenerative cooling of the inner shell for dry ash operation. A fuel flow and a combustion air flow having opposed swirls are mixed and burned in a mixing-combustion portion of the combustion volume and the ash laden combustion products flow with a residual swirl into an ash separation region. The ash is cooled below the fusion temperature and is moved to the wall by centrifugal force where it is entrained in the cool wall boundary layer. The boundary layer is stabilized against ash re-entrainment as it is moved to an ash removal annulus by a flow of air from the plenum through slots in the inner shell, and by suction on an ash removal skimmer slot.

Beaufrere, Albert H. (Huntington, NY)

1983-10-04

333

Radioactivity of ash from coal fired power stations (Macedonia)  

International Nuclear Information System (INIS)

In the lignite of the thermal power plant's surface mines there are uranium and thorium traces. Thorium-232 isotopes and uranium -238 and 235 isotopes are natural radioactive with a long period of half-decay. With the lignite combustion, thorium and uranium concentration occurs into the ash. Because of the fossil material old age, the products of the radioactive decay of all three radioactive series are in stationary condition, which results an equal activity of all isotopes in the series. Between the radioactive isotopes of each series there are ? and ? emitters which radiate ? quantum as well. The energy of ? and ? particles is of grate value for the radiation dose determination. While the ? quantum, because of its own penetration, play a special role in radiation intensity determination, as well as isotopes identification. In this paper the ash samples from the Thermal Power Plant 'Bitola' (Macedonia) are analysed. Gamma spectrometric analysis of the ash samples is done and presence of several isotopes of radioactive thorium and uranium series is confirmed. With the obtained results, the permitted doses of ash inhalation of neighbourhood population are defined

334

Suppression of fine ash formation in pulverized coal flames. Final technical report, September 30, 1992--January 31, 1996  

Energy Technology Data Exchange (ETDEWEB)

Coal ash, and particularly fine fly ash, remain one of the principal practical and environmental problems in coal-based power generation. In particular, submicron aerosols are identified with direct inhalation risk. Submicron ash is thought to arise from mineral vaporization during char combustion, followed by nucleation, condensation and coagulation to yield an aerosol. While aerosols are predominantly made out of volatile alkali minerals, they also can include refractory oxides that are chemically reduced to more volatile forms within the char particle and vaporized. Most of the ash of size greater than 1 {mu}m is generated by agglomeration of mineral as the char particle bums out. These two principal mechanisms are thought to account for most of the ash generated in coal combustion. Previous research has shown that various forms of coal treatment can influence the yields of fine ash from combustion. The research reported here investigates various forms of treatment, including physical coal cleaning, aerodynamic sizing, degree of grinding, and combinations of these on both aerosol yields and on yields of fine residual ash (1-4 {mu}m). The work also includes results from the combustion of artificial chars that include individual mineral elements. This research shows that these various forms of coal treatment can significantly change ash characteristics. While none of the treatments affected the bulk of the residual ash size distribution significantly, the yield of the ash aerosol mode (d<0.5 {mu}m) and fine residual ash mode (1-4 {mu}m) are changed by the treatments.

Kramlich, J.C.; Chenevert, B.; Park, Jungsung; Hoffman, D.A.; Butcher, E.K.

1996-07-19

335

Mixtures of coal ash and compost as substrates for highbush blueberry  

Energy Technology Data Exchange (ETDEWEB)

Bottom ash from a coal-fired power plant and two composts were tested as components of soil-free media and as soil amendments for growing highbush blueberry (Vaccinium corymbosum L.). Combinations of ash and compost were compared to Berryland sand, and Manor clay loam, and compost amended Manor clay loam. The pH of all treatment media was adjusted to 4.5 with sulfur at the beginning of the experiment. In 1997, plants of 'Bluecrop' and 'Sierra' were planted in 15-dm{sup 3} pots containing the pH-adjusted treatment media. The first substantial crop was harvested in 1999. At the end of the 1999 season, one half of the plants were destructively harvested for growth analysis. The remaining plants were cropped again in 2000. Yield and fruit size data were collected in both seasons, and leaf and fruit samples were collected in 1999 for elemental analysis. The presence of coal ash or composted biosolids in the media had no detrimental effect on leaf or fruit elemental content. Total growth and yield of both cultivars was reduced in clay loam soil compared to Berryland sand, whereas growth and yield of plants in coal ash-compost was similar to or exceeded that of plants in Berryland sand.

Black, B.L.; Zimmerman, R.H. [ARS, Beltsville, MD (USA). USDA Henry A Wallace Beltsville Agriculture Research Center, Fruit Lab.

2002-07-01

336

Catalytic oxidation of gaseous reduced sulfur compounds using coal fly ash  

International Nuclear Information System (INIS)

Activated carbon has been shown to oxidize reduced sulfur compounds, but in many cases it is too costly for large-scale environmental remediation applications. Alternatively, we theorized that coal fly ash, given its high metal content and the presence of carbon could act as an inexpensive catalytic oxidizer of reduced sulfur compounds for 'odor' removal. Initial results indicate that coal fly ash can catalyze the oxidization of H2S and ethanethiol, but not dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) at room temperature. In batch reactor systems, initial concentrations of 100-500 ppmv H2S or ethanethiol were reduced to 0-2 ppmv within 1-2 and 6-8 min, respectively. This was contrary to control systems without ash in which concentrations remained constant. Diethyl disulfide was formed from ethanethiol substantiating the claim that catalytic oxidation occurred. The presence of water increased the rate of adsorption/reaction of both H2S and ethanethiol for the room temperature reactions (23-25 deg. C). Additionally, in a continuous flow packed bed reactor, a gaseous stream containing an inlet H2S concentration of 400-500 ppmv was reduced to 200 ppmv at a 4.6 s residence time. The removal efficiency remained at 50% for approximately 4.6 h or 3500 reactor volumes. These results demonstrate the potential of using coal fly ash in reactors for removal of H2S and other reduced sulfur compoundsuced sulfur compounds

337

Regulations, environmentalist concerns and public perception on utilization of coal ash/cement mixtures in aquatic structures  

International Nuclear Information System (INIS)

A review of various state regulations regarding disposition of coal ash in the aquatic environment has been made. Some states encourage use of coal ash in cement formulations while others remain skeptical about its use due to concerns over leaching of various fraction into the aquatic environment. Almost all respondents indicated a requirement for ash residue management on land but few considered the marine environment as having significant merit. In general the public is poorly informed about the potential for beneficial use of coal ash in fabrication of structures for the marine and freshwater environments. Although researchers have studied the chemical and physical characteristics of cement fabricated with coal ash in the marine environment for over a decade little effort has been made to educate the public and potential users of the potential benefits. The author discusses the need to initiate a dialogue between people with different concerns and interests as a means to encourage greater recycling of coal ash. Various market potentials exist for utilization of coal ash in structures for use in aquatic environments. Some examples discussed include erosion control, wave breakers, offshore containment islands and artificial reefs

338

Glass Ceramics Composites Fabricated from Coal Fly Ash and Waste Glass  

International Nuclear Information System (INIS)

Great quantities of coal ash are produced in thermal power plants which present a double problem to the society: economical and environmental. This waste is a result of burning of coal at temperatures between 1100-14500C. Fly ash available as fine powder presents a source of important oxides SiO2, Al2O3, Fe2O3, MgO, Na2O, but also consist of small amount of ecologically hazardous oxides such as Cr2O3, NiO, MnO. The combination of the fly ash with waste glass under controlled sintering procedure gave bulk glass-ceramics composite material. The principle of this procedure is presented as a multi barrier concept. Many researches have been conducted the investigations for utilization of fly ash as starting material for various glass–ceramics production. Using waste glass ecologically hazardous components are fixed at the molecular level in the silicate phase and the fabricated new glass-ceramic composites possess significantly higher mechanical properties. The aim of this investigation was to fabricate dense glass ceramic composites using fly ash and waste glass with the potential for its utilization as building material

339

Hazards from radioactivity of fly ash of Greek coal power plants (CPP)  

International Nuclear Information System (INIS)

Fly ash and fine dispersion releases by coal combustion in Greek coal power plants are radioactive. Concentrations in the fly ash up to 20 pCi/g and 10 pCi/g were measured for 238U and 226Ra respectively (not in secular equilibrium). The radioactivity of fly ash deduces risks in two ways: a) from the escaping fly ash in particulate form or fine dispersion and b) from using fly ash as substitute for cement in concrete. In a room of dimensions 10 x 10x4 m3 the concentration of Radon in the air will be about 10-9 ?Ci/cm3. For the above estimation a concrete porosity of 5% and a wall thickness of 20 cm was used. The estimated concentration of Radon was about two orders of magnitude lower than that of the MPC of Radon in the air, which is about 10-9 ?Ci/cm3. It is pointed out that if a 25% porosity were used, the Radon concentration will be an order of magnitude higher. (U.K.)

340

Alpha radioactivity study in coal-ash of thermal power plant using solid state nuclear track detector  

International Nuclear Information System (INIS)

Coal combustion in power plants in India produces large quantities coal related wastes, for example flyash and bottom ash. Coal is known to contain trace quantities of naturally occurring radionuclides including uranium. Thus coal ash is also expected to contain those radionuclides. Flyash has become the subject of worldwide interest because of its diverse uses as in the manufacturing of cement, bricks, blocks, etc. Due to presence of higher concentration of primordial radionuclide content it may cause a potential health risk to people. The power plant- ash, if not properly disposed, will be a serious threat to the ambient environment. So it is essential to investigate the presence of radioactivity in the coal ash samples collected from different thermal power plants. In the present work, an attempt has been made to estimate the alpha activity in the coal ash samples collected from Kolaghat Thermal Power Plant, West Bengal using CR-39 plates - a very useful solid state nuclear track detector (SSNTD). It is one of the largest thermal power generation centres in West Bengal. This thermal power plant uses sub-bituminous coal from the nearby coalfields. The alpha activity of the samples varies from 1052-3571 Bq/kg. The analysis indicates high level of alpha activity in both fly and bottom ash and the level of activity are maximum among all power plant flyash of India reported so far. (author)

341

Plant growth and trace-element uptake on acidic coal refuse amended with lime or fly ash  

Energy Technology Data Exchange (ETDEWEB)

Two commonly used revegetation species, Kentucky 31 tall fescue (Festuca arundinacea Schreb.) and Lincoln smooth brome (Bromus inermis Leyss.), were grown for 60 days in pots containing coarse coal mine refuse (referred to as gob, pH = 3.5) amended with either lime or alkaline powerplant fly ash. Both species were also grown in pots containing a silt loam surface soil as a control. Morphological growth parameters were measured over time; dry weights and shoot/root ratios were determined at harvest. Concentrations of Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, V, and Zn in the plant shoots were determined by atomic absorption spectrophotometry. Plant growth of both species was not as good on either lime- or fly ash-amended gob as it was on surface soil; however, more vigorous growth occurred on lime-amended gob than on fly ash-amended gob. Significant differences (rho < 0.05) in the tissue concentrations of Cd, Co, Fe, Hg, Mn, Pb, V, and Zn were found among the plants grown on the three substrates. Except for Hg and Pb, these elements were higher in plants grown on at least one of the amended-gob substrates than in plants grown on surface soil. Significant substrate differences were not observed for Al, As, Cr, Cu, Ni, and Se. The tissue concentrations of some elements - notably Al, Cu, Fe, Mn, V, and Zn - were high enough in plants from one or more of the substrates to either approach or exceed concentrations which have been reported to be associated with toxic effects in some plant species.

Jastrow, J.D. (Argonne National Lab., IL); Zimmerman, C.A.; Dvorak, A.J.; Hinchman, R.R.

1981-04-01

342

Coal fly ash-slag-based geopolymers: Microstructure and metal leaching  

Energy Technology Data Exchange (ETDEWEB)

This study deals with the use of fly ash as a starting material for geopolymeric matrices. The leachable concentrations of geopolymers were compared with those of the starting fly ash to evaluate the retention of potentially harmful elements within the geopolymer matrix. Geopolymer matrices give rise to a leaching scenario characterised by a highly alkaline environment, which inhibits the leaching of heavy metals but may enhance the mobilization of certain oxyanionic species. Thus, fly ash-based geopolymers were found to immobilise a number of trace pollutants such as Be, Bi, Cd, Co, Cr, Cu, Nb, Ni, Pb, Sn, Th, U, Y, Zr and rare earth elements. However, the leachable levels of elements occurring in their oxyanionic form such as As, B, Mo, Se, V and W were increased after geopolymerization. This suggests that an optimal dosage, synthesis and curing conditions are essential in order to obtain a long-term stable final product that ensures an efficient physical encapsulation.

Izquierdo, Maria, E-mail: mariaizq@ija.csic.es [Institute of Earth Sciences ' Jaume Almera' -CSIC, Lluis Sole Sabaris s/n 08028 Barcelona (Spain); Querol, Xavier [Institute of Earth Sciences ' Jaume Almera' -CSIC, Lluis Sole Sabaris s/n 08028 Barcelona (Spain); Davidovits, Joseph [Cordi-Geopolymere, Espace Creatis, Z.A. Bois de la Chocque 02100 Saint-Quentin (France); Antenucci, Diano [Institut Scientifique de Service Public (ISSeP) 200, rue du Chera, B-4000 Liege (Belgium); Nugteren, Henk [Delft University of Technology, Faculty of Applied Sciences, DelftChemTech, Particle Technology Group, Julianalaan 136, 2628 BL Delft (Netherlands); Fernandez-Pereira, Constantino [University of Seville, School of Industrial Engineering, Department of Chemical and Environmental Engineering, Camino de los Descubrimientos s/n, 41092 Seville (Spain)

2009-07-15

343

Uses of the ashes resulted from the thermopower plant based on coal, with an impact on the population exposure to the nuclear radiations  

International Nuclear Information System (INIS)

Each year large quantities of ashes from the coal combustion are produced around the world, the flying ashes as well as the slag are included in this category of ashes. For economical reasons, a large variety of coal ash applications haas been found, the most important being its utilizations in the cement and concrete fabrication. Some types of concrete include up to 80% flying ashes. The ash resulted from the coal is also used as a stabilizer in the roads fill up mixed with bitumen as a soil amendment or fertilizer in agriculture. All these utilizations of the coal ashes can lead to an increase of the people exposure due to the natural irradiation sources. The paper tries to give an answer based on laboratory analysis and adequate calculations concerning the danger of radioactive contamination in case of using the flying ashes, resulting from burning of coal in thermopower plant in the building materials industry. (author)

344

Geochemical and hydrogeologic evolution of alkaline discharges from abandoned coal mines  

International Nuclear Information System (INIS)

Numerous large flow (> 2,000 l/min), historically (pre-1973) acidic, abandoned underground deep mine discharges in southwestern Pennsylvania are now alkaline in character, with circumneutral pH. Recently measured flow rates are consistent with those measured 25--30 years ago; thus the change in chemistry is not simply due to dilution by increased flows of uncontaminated water through the mines. It is likely that flooding of the mines has decreased the extent of acidity enhancing aerobic conditions, and that decades of weathering have reduced the amount of reactive pyrite. However, the mines continue to yield a sulfate-rich, Fe-contaminated (19--79 ppm) drainage. These highly alkaline discharges (up to 330 ppm as CaCO3) are accompanied by large concentrations of sodium (up to 700 ppm) and suggest cation exchange with the associated overburden. To assess the hydrogeological conditions that result in the formation of alkaline Fe-contaminated mine discharges, the authors examined all the major discharges from a single synclinal basin. The northeast-trending Irwin synclinal coal basin encompasses 94 mi2 and was extensively mined by underground methods during the first half of this century. All major streams that arise within or cross the syncline are polluted by mine drainage that ranges from highly acidic Fe- and Al-contaminated discharges in the northern portion of the syncline to highly alkaline, iron and sulfate-contaminated discharges to the soutulfate-contaminated discharges to the south. The hydrology of the basin is controlled by its southern plunging structure, by outcrops or drainage tunnels on the western arms of the syncline, and by several coal barriers. A first-order hydrogeologic model was constructed to evaluate ground water flow into and through the mine complexes found in the basin. The model integrates the basin geometry with structural and mine barrier components to determine groundwater flow paths and estimate residence time. Water quality is related to the cumulative proportion of up-gradient flooded and unflooded mine workings. Small discharges from unflooded, gravity-flow portions of the mined-out portion of the Pittsburgh Coal seam are highly acidic, and large artesian flows of water affected by only a short flow through flooded anoxic mine pools are moderately acidic. Those discharges subjected to increased residence time in flooded anoxic portions of the mines are increasingly alkaline. Refinement of this model could aid in prediction and hydrogeologic manipulation of these high flow Fe-contaminated discharges that are the main pollutant in many streams throughout Northern Appalachia and other coal mining areas throughout the world

345

Nitric Oxide Removal from Flue Gases by Carbon-enriched Coal Fly Ash  

OpenAIRE

The aim of this work is to evaluate the characteristics of activated and non-activated carbon obtained from carbon-enriched coal fly ashes (CECFA) from two different power stations to be used in the low temperature reduction of NO from stack gases. Carbon-rich fractions were obtained by mechanical sieving of fly ashes and by oil agglomeration. Activation of some samples was carried out in steam at 900ºC in order to develop porosity onto the samples. The obtained activated and non-activated s...

Begoña Rubio; Maria Teresa Izquierdo

2013-01-01

346

Unburnt carbon from coal fly ashes as a precursos of activated carbon for nitric oxide removal  

OpenAIRE

The aim of this work is to evaluate the characteristics of an activated carbon obtained from unburnt carbon in coal fly ashes to be used in the removal of NO. Carbon-rich fraction was obtained by mechanical sieving of fly ashes. The mineral matter was removed by conventional HCl and HF desmineralization procedure. Activation was carried out with steam at 900ºC in order to develop porosity onto the sample. Characterization of samples was performed by several techniques with a m...

Rubio Villa, Begon?a; Izquierdo Pantoja, Mari?a Teresa

2007-01-01

347

Mercury capture by native fly ash carbons in coal-fired power plants  

OpenAIRE

The control of mercury in the air emissions from coal-fired power plants is an on-going challenge. The native unburned carbons in fly ash can capture varying amounts of Hg depending upon the temperature and composition of the flue gas at the air pollution control device, with Hg capture increasing with a decrease in temperature; the amount of carbon in the fly ash, with Hg capture increasing with an increase in carbon; and the form of the carbon and the consequent surface area of the carbon, ...

Hower, James C.; Senior, Constance L.; Suuberg, Eric M.; Hurt, Robert H.; Wilcox, Jennifer L.; Olson, Edwin S.

2010-01-01

348

Successive development of soil ecosystems at abandoned coal-ash landfills.  

Science.gov (United States)

The main goal of the present study was to determine the effect of the native vegetation on the successive development of the soil ecosystem at abandoned coal-ash landfills of the Angren coal-fired power plant in Uzbekistan. Two different landfills (one not in use for 3 years, termed newer, and the other not in use for 10 years, termed older) with different degrees of vegetation cover were chosen to assess the time and vegetation effects on soil biota and habitat development. The soil biotic structure, including soil microorganisms and soil free-living nematode communities, was investigated both at open plots and under different native plants at the coal-ash landfill area. The observed soil microorganisms were found to be the most important component of the observed ecosystems. Total abundance, biomass, species, trophic and sexual diversity of soil free-living nematodes, along with fungi and organic-matter content, were found to be correlated with trace metals. The nematode trophic and species abundance and diversity increased from the newer toward the older coal-ash landfills. The sex ratio of the nematode communities was found to be dependent on the environmental conditions of the study area, with the males being the most sensitive nematode group. All applied ecological indices confirmed that open landfill plots distant from plants are the most unfavorable areas for soil biota. In that respect, the native plants Alhagi maurorum Desv. and Tamarix sp. were found to be important environmental components for the natural remediation of a soil ecosystem in the coal-ash landfill area. PMID:24676936

Pen-Mouratov, Stanislav; Shukurov, Nosir; Yu, Jun; Rakhmonkulova, Shakhnoza; Kodirov, Obidjon; Barness, Gineta; Kersten, Michael; Steinberger, Yosef

2014-07-01

349

Analysis of naturally-occurring radionuclides in coal combustion fly ash, gypsum, and scrubber residue samples.  

Science.gov (United States)

Coal combustion residues from coal-fired power plants can be advantageous for use in building and construction materials. These by-products contain trace quantities of naturally occurring radionuclides from the uranium and thorium series, as well as other naturally occurring radionuclides such as K. Analysis was performed on samples of coal fly ash, flue gas desulfurization, gypsum and scrubber sludges, fixated scrubber sludges, and waste water filter cakes sampled from multiple coal-fired power plants in the United States. The radioactive content of U and Th decay series nuclides was determined using gamma photopeaks from progeny Pb at 352 keV and Tl at 583 keV, respectively; K specific activities were determined using the 1,461 keV photopeak. The samples were hermetically sealed to allow for secular equilibrium between the radium parents and the radon and subsequent progeny. Samples were analyzed in a common geometry using two high purity germanium photon detectors with low energy detection capabilities. The specific activities (Bq kg) were compared to results from literature studies including different building materials and fly ash specific activities. Fly ash from bituminous and subbituminous coals had U specific activities varying from 30-217 Bq kg (mean + 1 s.d. 119 ± 45 Bq kg) and 72-209 Bq kg (115 ± 40 Bq kg), respectively; Th specific activities from 10-120 Bq kg (73 ± 26 Bq kg) and 53-110 Bq kg (81 ± 18 Bq kg), respectively; and K specific activities from 177 to 928 Bq kg (569 ± 184 Bq kg) and 87-303 Bq kg (171 ± 69 Bq kg), respectively. Gypsum samples had U, Th, and K specific activities approximately one order of magnitude less than measured for fly ash samples. PMID:23361421

Roper, Angela R; Stabin, Michael G; Delapp, Rossane C; Kosson, David S

2013-03-01

350

Fate of the naturally occurring radioactive materials during treatment of acid mine drainage with coal fly ash and aluminium hydroxide.  

Science.gov (United States)

Mining of coal is very extensive and coal is mainly used to produce electricity. Coal power stations generate huge amounts of coal fly ash of which a small amount is used in the construction industry. Mining exposes pyrite containing rocks to H2O and O2. This results in the oxidation of FeS2 to form H2SO4. The acidic water, often termed acid mine drainage (AMD), causes dissolution of potentially toxic elements such as, Fe, Al, Mn and naturally occurring radioactive materials such as U and Th from the associated bedrock. This results in an outflow of AMD with high concentrations of sulphate ions, Fe, Al, Mn and naturally occurring radioactive materials. Treatment of AMD with coal fly ash has shown that good quality water can be produced which is suitable for irrigation purposes. Most of the potentially toxic elements (Fe, Al, Mn, etc) and substantial amounts of sulphate ions are removed during treatment with coal fly ash. This research endeavours to establish the fate of the radioactive materials in mine water with coal fly ash containing radioactive materials. It was established that coal fly ash treatment method was capable of removing radioactive materials from mine water to within the target water quality range for drinking water standards. The alpha and beta radioactivity of the mine water was reduced by 88% and 75% respectively. The reduced radioactivity in the mine water was due to greater than 90% removal of U and Th radioactive materials from the mine water after treatment with coal fly ash as ThO2 and UO2. No radioisotopes were found to leach from the coal fly ash into the mine water. PMID:24355687

Madzivire, Godfrey; Maleka, Peane P; Vadapalli, Viswanath R K; Gitari, Wilson M; Lindsay, Robert; Petrik, Leslie F

2014-01-15

351

Analysis of trace elements in coal fly ash and their leachates: results of the ENEL-EDF round robin test  

Energy Technology Data Exchange (ETDEWEB)

The present study deals with the assessment and improvement of trace element analysis reliability in coal ash and coal ash leachates. Eight Italian Laboratories from ENEL and four French laboratories from EDF took part in this test. Two samples were studied (a certified reference material NIST 1633a and a fly ash with unknown unconcentration coming from an Italian coal-fired power plant) and eleven trace elements (As, Cd, Cr, Cu, Hg, Ni Ph, Sb, Se, V and Zn) were analysed. A `standardised` mineralization procedure for the fly ash samples, which employs a microwave oven was validated by means of this Round Robin Test. For the analysis step, flame atomic absorption spectrometry (FAAS), graphite furnace atomic absorption spectrometry (GFAAS) or inductively coupled plasma atomic emission spectrometry (ICP-AES) were employed. Leaching tests were applied to the unknown ash sample, following the Italian standard test (IRSA, using acetic acid) and the French standard test (AFNOR, using demineralized water).

Bettinelli, M.; Spezia, S.; Quattroni, G.; Giove, A. [Enel SpA, Brindisi (Italy)

1998-03-01

352

Adsorption of Iron by Fly Ash Adsorbent of Coal  

Directory of Open Access Journals (Sweden)

Full Text Available Normal 0 false false false IN X-NONE X-NONE MicrosoftInternetExplorer4 Normal 0 false false false IN X-NONE X-NONE MicrosoftInternetExplorer4 This research has investigated adsorption of Fe with using fly ash adsorbent. Phases of adsorption of Fe is activated with H2SO4 after that the fly ash were characterized by using XRF, FTIR and SEM. Determination of optimum conditions on the adsorption of Fe with adsorbent mass variations, variations in contact time, pH variation and variation concentration and adsorption isotherm study. Resulth show that the adsorption of Fe in optimum condition occurs in adsorbent mass of 2.5 g, for 60 minutes contact time with pH 4 at a concentration of 20 ppm. The results also able to adsorp up to 94% Fe. The adsorption of Fe with using fly ash adsorbent was more fitted to the Langmuir model than to Freundlich model

Candra Irawan

2014-04-01

353

Mercury removal from coal combustion flue gas by fly ash  

Energy Technology Data Exchange (ETDEWEB)

The effect of physicochemical properties on the mercury adsorption performance of three fly ash samples has been investigated. The samples were tested for mercury adsorption using a fixed-bed with a simulated gas. X-ray fluorescence spectroscopy, X-ray photoelectron spectroscopy and other methods were used to characterize the samples. The results indicate that mercury adsorption on fly ash is mainly physisorption and chemisorption. Uncompleted burned carbon is an important factor for the improvement of mercury removal efficiency, especially, the C-M bond may improve the oxidation of mercury, which formed via the reaction of C and Ti, Si and other elements. The higher specific surface areas and smaller pore diameter are all beneficial for the high mercury removal efficiency. The presence of O{sub 2} plays a positive role on Hg adsorption of modified fly ash, while SO{sub 2} has double role of inhibition because of competitive adsorption and promotion to chemisorption. In addition, sample modified with FeCl{sub 3} has a great performance in Hg removal.

Kuang, Junyan [Chinese Academy of Sciences, Beijing (China). Research Center for Process Pollution Control; Chinese Academy of Sciences, Beijing (China). Graduate Univ.; Xu, Wenqing; Zhu, Tingyu; Jing, Pengfei [Chinese Academy of Sciences, Beijing (China). Research Center for Process Pollution Control

2013-07-01

354

Effect of coal fly ash and co-composted sewage sludge on emergence and early growth of cover crops  

Energy Technology Data Exchange (ETDEWEB)

Fly ash, a by-product of coal combustion, is often stored in landfills. Stabilization of fly ash deposits can be hindered by phytotoxic levels of B and soluble salts in the ash. Two greenhouse studies were conducted with the objective of improving cover crop establishment on landfills containing fly ash. In one experiment, eight cover crop species were screened for tolerance to fly ash and fly ash-amended soil, as measured by seedling emergence and early shoot growth. Hairy vetch, red clover, and tall fescue were identified as having the best potential for stabilization of fly ash deposits. Another experiment determined if amending fly ash with a co-compost produced from municipal refuse and sewage sludge, would improve the establishment and growth of tall fescue and Korean lespedeza. The co-compost had no effect on fescue alone, but increased emergence and early growth of lespedesa and a fescue-lespedeza mixture.

Sims, J.T.; Vasilas, B.L.; Gbodrati, M. (Delaware Univ., Newark, DE (USA). Dept. of Plant and Soil Science)

1993-01-01

355

Field trial of a pair production gauge for the on-line determination of ash in coal  

International Nuclear Information System (INIS)

The ash content of coal can be determined by a method based on pair production. Coal is irradiated with high energy gamma-rays and 0.511 MeV annihilation and Compton scattered gamma-rays measured. Earlier laboratory tests on 50 kg samples of high ash coals gave errors of 0.46 to 1.3 wt% ash. A plant test to assess the pair production gauge for direct on-line conveyor belt analysis is described. This test was carried out on a recirculating coal loop at a Broken Hill Pty. Ltd. coal washery pilot plant. Samples were measured on-belt as a function of sample depth, compaction, moisture and particle size. The technique was found to provide accurate measurements of the ash content of coal in a constant geometry. It can be used to determine ash content of coal of thickness 60-220 mm on a conveyor belt by an additional measurement of the weight per unit area of coal on the belt by ?-ray transmission

356

Properties of Concrete using Tanjung Bin Power Plant Coal Bottom Ash and Fly Ash  

OpenAIRE

Coal combustion by-products (CCPs) have been around since man understood that burning coal generates electricity, and its utilization in concrete production for nearly a century. The concept of sustainable development only reawaken our consciousness to the huge amount of CCPs around us and the need for proper reutilization than the current method of disposal which has  severe consequences both to man and the environment. This paper presents the result of utilization of waste from thermal...

Abdulhameed Umar Abubakar; Khairul Salleh Baharudin

2012-01-01

357

Alkaline disinfection of urban wastewater and landfill leachate by wood fly ash.  

Science.gov (United States)

Abstract Wood fly ash is an industrial by-product of the combustion of different wood materials and is mostly disposed of as waste on landfills. In our preliminary experiments, wood ash exhibited antibacterial activity against urban wastewater bacteria and we focused on wood fly ash as a potential substrate for wastewater disinfection. The addition of ash at a concentration of 10 g L-1 (1 %) caused an instant increase of pH in urban wastewater and landfill leachate. High pH (10.1-12.7) inactivated bacterial populations in the wastewater and the removal of faecal coliforms and intestinal enterococci after 6 h of contact was 100 % (below the detection limit; <1 CFU per mL) with the most efficient ash sample (ash from combustion of beech) both in urban wastewater and landfill leachate. Properly chosen wood fly ash, i.e. one that tends to increase the pH to the greatest extent, proved to be a very effective disinfection substrate. Considering that water treated with wood ash has a high pH and needs to be neutralised before discharge, ash would be suitable for disinfection of leachates when smaller volumes are treated. PMID:25720024

Ivankovi?, Tomislav; Hrenovi?, Jasna; Itskos, Grigorios; Koukouzas, Nikolaos; Kova?evi?, Davor; Milenkovi?, Jelena

2014-12-01

358

Hydrothermal Synthesis of Zeolite from Coal Class F Fly Ash. Influence of Temperature  

Directory of Open Access Journals (Sweden)

Full Text Available The influence of temperature of alkaline hydrothermal treatment on the conversion in zeolite of Spanish coal low calcium-fly ash (ASTM class F is presented in this work. Zeolite Na-P1 gismondine type (Na6Al6Si10O32.12H2O was formed at the temperature of 100ºC, which transformed in zeolite; analcime-C type (Na(Si2AlO6H2O and sodalite (1.08 Na2O.Al2O3.1.68SiO2.1.8H2O at 200ºC together with traces of tobermorite-11Å (Ca5(OH2Si6O16.4H2O. At this temperature the 100% of the fly ash reaction was allowed. An equivalent study was carried out in water as reference. The zeolite conversion of the fly ash was characterized by X ray diffraction (XRD, FT infrared (FTIR spectroscopy, surface area (BET-N2 and thermal analyses.

En este trabajo se presenta el papel que juega la temperatura durante el tratamiento hidrotermal en medio alcalino para convertir una ceniza volante de bajo contenido en cal (clase F, según la norma ASTM en zeolita. Durante este tratamiento a la temperatura de 100ºC se forma Zeolita Na-P1 tipo gismondina (Na6Al6Si10O32.12H2O; al elevar la temperatura a 200ºC, dicha zeolita se transforma en zeolita Analcima C (Na(Si2AlO6H2O y en fase sodalita (1.08 Na2O.Al2O3.1.68SiO2.1.8H2O junto con trazas de tobermorita-11Å (Ca5(OH2Si6O16.4H2O. A esta temperatura y en estas condiciones se ha conseguido un 100% de reacción. Un estudio equivalente se ha llevado a cabo empleando agua como medio de referencia. La conversión de ceniza volante en zeolita se ha caracterizado mediante técnicas, como difracción de Rayos X (DRX, espectroscopia infrarroja por transformada de Fourier (FTIR y análisis térmico (TG/ATD; así mismo los cambios en el área superficial se han llevado a cabo mediante la técnica BET-N2.

Goñi, S.

2010-06-01

359

Some controls on the ash composition of Waikato coals  

Energy Technology Data Exchange (ETDEWEB)

Major element analyses, and some mineralogical analyses, are presented for ply samples taken from major coal seams at several opencast mines in the Huntly and Rotowaro Coalfields. These analyses confirm previous work indicating the strong organic association of Ca, Mg, Na, and Fe. The abundance of these elements in individual seams appears to be influenced by the presence or absence of overlying coal seams, which may have controlled the circulation of groundwater either when the organically associated elements were fixed, or during a subsequent expulsion period. Na values in a split Taupiri seam at Maori Farm Opencast vary across major sediment partings, being highest in the lowermost coal interval. Si/Al ratios vary widely, and commonly fall below the limit of kaolinite, indicating breakdown of silicates and transport of probably both silica and alumina in solution at the time of peat accumulation. Ti and P in whole coal fluctuate substantially, and their present distribution indicates mobility in solution. P concentrations may be related to nutrient influx accompanying sedimentation in the peat. Few minerals were identified in LTA. Si, Al and K are hosted by quartz, kaolinite, and traces of illite, and Ti occurs at least partly as anatase. 13 refs., 9 figs., 2 tabs.

Newman, N.A.; Newman, J. [University of Canterbury, Christchurch (New Zealand). Dept. of Geology

1993-12-31

360

Experimental study of fly ash of Lakhra coal power plant in RCC beams  

International Nuclear Information System (INIS)

Of the various industrial by-products, fly ash, a finely divided mineral residue generated from the combustion of pulverized coal in power plants, is the most abundant. Its utilization as mineral admixture in cement concrete transforms a costly liability into an economical proposition. Further more, the costs and environmental problems associated with its disposal are minimized or eliminated. This study comprises on RCC beams made with ordinary Portland cement and with different configurations of fly ash by replacing cement and fine aggregate. To achieve the aim of present study, total 27 RCC beams were made. Among 27 beams, 3 beams were made with normal concrete, 12 beams were made by replacing 25, 50, 75 and 100% of fine aggregate by fly ash and 12 beams were made by replacing 10, 25, 50, and 75% of cement by fly ash. The study of these beams was carried out in terms of Load deflection, ultimate strength, crack pattern and failure mode. By analyzing the test results, it was observed that the beams made by replacing 75% of fine aggregate by fly ash with 4 and 6 stirrups has shown less deflection and higher ultimate load carrying capacity whereas the beams made by replacing 50 and 75% of-cement by fly ash have given inferior behaviour in comparison to the beam made by ordinary portland cement concrete. (author)

361

Optimization of low activity spectrometric gamma-gamma probes for ash determination in coal stockpiles.  

Science.gov (United States)

A stockpile probe based on backscattered gamma-gamma-ray technique was tested for the determination of coal ash. A centralized tool employing a gamma-ray source of very low radioactivity (1.85 MBq) was used. This logging tool was tested using 137Cs and 133 Ba sources with a 37 mm (diameter) by 75 mm NaI (TI) scintillation detector. Ten source-detector configurations were analyzed using 137Cs, and another nine source-detector configurations are analyzed, using 133Ba source, both for four geophysical models, having a borehole diameter of 90 mm. Regression analysis on the laboratory logging data for each studied configuration was carried out in order to establish calibration equations for ash prediction. The optimum configuration for the logging stockpile probe using 137Cs source was determined to be 80 mm source to detector spacing, and 80 mm iron thickness shielding. This configuration gives the best results for ash prediction. The root mean square (rms) deviation for ash is 1.52%. The optimum configuration for the logging stockpile probe using 133 Ba source is determined to be 85 mm source to detector spacing, and 50mm iron thickness shielding. This configuration gives the best results for ash prediction, where the rms deviation for ash is 1.47%. PMID:12798372

Asfahani, Jamal

2003-06-01

362

Feasibility studies of low energy #betta#-ray techniques for on-line determination of ash content of coal on conveyors  

International Nuclear Information System (INIS)

Low energy #betta#-ray transmission measurements on suites of 100 kg samples from each of four different coal areas of Australia gave errors in ash determination of 0.99, 1.20, 1.59 and 2.24 wt% (1?), respectively, for mean ash contents of 20.0, 27.1, 24.5 and 17.1 wt% ash. Calculations show that the main errors in ash determination are caused by variations of Fe2O3 in the ash, and the wt% ash error is proportional to the ash concentration. An error of about 0.5 wt% is predicted for washery product with ash content of 8 wt%. The most promising applications of low energy #betta#-ray techniques are for direct on-line determination of ash in washed coal, and for raw coal where accuracy required is not high or iron variations in the ash are small. (author)

363

Sulfur retention by ash during coal combustion. Part II. A model of the process  

OpenAIRE

An overall model for sulfur self-retention in ash during coal particle combustion is developed in this paper. It is assumed that sulfur retention during char combustion occurs due to the reaction between SO2 and CaO in the form of uniformly distributed non-porous grains. Parametric analysis shows that the process of sulfur self-retention is limited by solid difussion through the non-porous product layer formed on the CaO grains and that the most important coal characteristics which influence ...

BRANIMIR JOVANCICEVIC; MLADEN ILIC; BORISLAV GRUBOR; VASILIJE MANOVIC

2003-01-01

364

Ultrasonic coal-wash for de-ashing and de-sulfurization. Experimental investigation and mechanistic modeling  

Energy Technology Data Exchange (ETDEWEB)

This study focuses on the physical aspects of ultrasonic de-ashing and de-sulfurization, such as cavitation, streaming and their combined effects. Ambedkar Balraj proposes an ultrasound-assisted coal particle breakage mechanism and explores aqueous and solvent-based ultrasonic techniques for de-ashing and de-sulfurization. Ambedkar designs a Taguchi L-27 fractional-factorial matrix to assess the individual effects of key process variables. In this volume he also describes process optimization and scale-up strategies. The author provides a mechanism-based model for ultrasonic reagent-based coal de-sulfurization, proposes a flow diagram for ultrasonic methods of high-throughput coal-wash and discusses the benefits of ultrasonic coal-wash. Coal will continue to be a major fuel source for the foreseeable future and this study helps improve its use by minimising ash and sulfur impurities.

Ambedkar, B. [Indian Institute of Technology Madras, Chennai (India). Dept. of Chemical Engineering

2012-07-01

365

Lognormal distribution of natural radionuclides in freshwater ecosystems and coal-ash repositories  

International Nuclear Information System (INIS)

This study summarizes and analyses data for natural radionuclides, 40K, 226 Ra and 'Th, measured by gamma spectrometry in water samples, sediments and coal-ash samples collected from regional freshwater ecosystems and near-by coal-ash repositories during the last decade, 1986-1996, respectively. The frequency plots of natural radionuclide data, for which the hypothesis of the regional scale log normality was accepted, exhibited single population groups with exception of 226Ra and232Th data for waters. Thus the presence of break points in the frequency distribution plots indicated that 226Ra and 232Th data for waters do not come from a single statistical population. Thereafter the hypothesis of log normality was accepted for the separate population groups of 226 Ra and '-32 Th in waters. (authors)

366

Synthesis and characterization of zeolite material from coal ashes modified by surfactant  

International Nuclear Information System (INIS)

Coal ash was used as starting material for zeolite synthesis by means of hydrothermal treatment. The surfactant-modified zeolite (SMZ) was prepared by adsorbing the cationic surfactant hexadecyltrimethylammonium bromide (HDTMA-Br) on the external surface of the zeolite from coal ash. The zeolite structure stability was monitored during the characterization of the materials by FTIR, XDR and SEM. The structural parameters of surfactant-modified zeolite are very close to that of corresponding non-modified zeolite which indicates that the crystalline nature of the zeolite remained intact after required chemical treatment with HDTMA-Br molecules and heating treatment for drying. The most intense peaks in the FTIR spectrum of HDTMA-Br were observed in SMZ spectrum confirming adsorption of surfactant on zeolites. (author)

367

Valorization of coal fly ash by mechano-chemical activation Part II. Enhancing pozzolanic reactivity  

Energy Technology Data Exchange (ETDEWEB)

The pozzolanic and adsorptive characteristics of coal fly ash have been enhanced by mechano-chemical activation in order to evaluate their potential utilization in the stabilization/solidification treatment of hazardous wastes. To that aim a soil artificially contaminated by large amounts of Phenol and Pb underwent that treatment, wherein increasing amounts of powder activated carbon and Portland cement were substituted by mechano-chemically activated fly ash. Under the experimental conditions investigated, very encouraging results, in terms of contaminants leaching and mechanical properties of the stabilized/solidified matrix, were obtained when up to 100% of the powder activated carbon and up to 50% of the Portland cement were substituted by mechano-chemically activated fly ash, thus opening improved possibilities for using this latter in environmental applications.

Stellacci, P.; Liberti, L.; Notarnicola, M.; Bishop, P.L. [Technical University of Bari, Taranto (Italy). Dept. of Environmental Engineering & Sustainable Development

2009-07-15

368

Method for removal of last traces of soluble ash and elements from solvent refined coal  

Energy Technology Data Exchange (ETDEWEB)

Solvent refined coal is treated with liquid water at a temperature of about 500 to 550/sup 0/F in a closed cylindrical vessel under the saturation pressure 665 to 1030 psig of water at that temperature and under gentle agitation to insure low shear liquid-solid contact for about 1/2 to 2 hours. Surprisingly, the soluble ash, generally sodium or potassium salts, is leached out to bring the sodium content down from 50 to 60 parts per million to a value of less than 1 part per million which makes the product very suitable as a feed for direct firing in a gas turbine. In addition the total ash content is reduced from a value of approximately 0.1 percent to a value less than 0.05 percent which means that in addition to reducing the quantity of sodium and potassium, there are other constituents of the ash which also have been removed.

Kindl, F.H.

1978-06-20

369

Assessment of compost application to coal ash disposal sites to promote the rapid vegetation establishment  

Science.gov (United States)

In the city of Tuzla, located in Bosnia and Herzegovina, a coal fired thermo electric power plant is operated by the company JP ELEKTROPRIVERDA BIH TERMOELEKTRANA "TUZLA". High amounts of ash are produced by the power plant, which are currently disposed into settlement ponds bordered by dams in natural valleys. A total of four ash disposal sites covering an area of approx. 170 ha have been established during the last decades. Due to the fact that residual ash from coal combustion was found to contain a variety of trace elements (Ni, Cr, As, B), it must be assumed that ash disposal of that magnitude constitutes an environmental problem which is investigated within the EU-FP6 / STREP project "Reintegration of Coal Ash Disposal Sites and Mitigation of Pollution in the West Balkan Area" RECOAL. The main hazards relate to soil and groundwater contamination due to leaching toxins, dust dispersion, and toxins entering the food chain as these disposal sites are used for agricultural purposes. In order to rapidly establish a vegetation cover on barren ash dumps that particularly would prevent dust erosion we assessed the applicability of compost, produced from locally available municipal and industrial organic residues as an amendment to ash to improve substrate fertility. The envisaged remediation technology was considered to be a low cost, easy applicable and rapid method capable of substantially enhancing living conditions of residents in the vicinity of the abandoned disposal sites. Various compost application rates were evaluated in the field on experimental site Divkovici I in Tuzla and additionally in the greenhouse environment at Brandenburg Technical University Cottbus. Field and laboratory tests revealed that plant growth and cover rate can substantially be improved by mixing compost into the upper ash layer to a maximum depth of approx. 20 cm. Besides direct growth observations in the field analysis of soil parameters gave evidence that the fertility of ashy substrates amended with compost produced from locally available sewage sludge and saw dust can be improved. The metal content of grass grown in the various treatments was considered to be elevated compared to normal contents. However, metal uptake in compost treatments was lower than in untreated plots. A preliminary cost assessment, comparing the remediation technology tested on site Divkovici with a standard soil covering technique revealed financial benefits for the compost method due to significant lower application rates.

Repmann, F.; Slazak, A.; Babic, M.; Schneider, B. U.; Schaaf, W.; Hüttl, R. F.

2009-04-01

370

The analysis of coal-and coke ashes by atomic absorption spectrophotometry  

International Nuclear Information System (INIS)

In order to provide better conditions for the control of the chemical composition of the load in the USIMINAS blast furnaces, a method of analysis for sodium, potassium, iron, aluminium, calcium, magnesium and maganese in coal-and coke ash by atomic absorption spectrophotometry was developed. The precision of the calibration curves and the reproducibility of the results are given, together with an estimate of the speed compared with conventional methods of chemical analysis

371

Potential Use of Malaysian Thermal Power Plants Coal Bottom Ash in Construction  

OpenAIRE

As Malaysia focuses its attention to the call for a “greener” culture, so did the engineers and those in the scientific community especially the construction industry who is a major contributor to the depletion of green house gases. The engineering and construction community has now taken up the challenge for the use of “green and recycled by-products” in construction. One of those by-products is the Coal Bottom Ash (CBA) from thermal power plants that faces an increas...

Abdulhameed Umar Abubakar; Khairul Salleh Baharudin

2012-01-01

372

Determination of Ca and Fe and measurement of the ash content of brown coal  

International Nuclear Information System (INIS)

The XRF technique and the low-energy X-ray backscattering method have been applied to the determination of calcium and iron and the measurement of the ash content of brown coal. A 238Pu source, an argon-filled proportional counter and a three-channel pulse-height analyzer were used. A simple theoretical model is proposed. The obtained results are discussed. (author)

373

Removal of organic sulfur from coal by wheat straw ash and potassium ferric hexacyanoferrat (II)  

Energy Technology Data Exchange (ETDEWEB)

This study is an attempt to desulfurize organic sulfur from coal samples with potassium ferric hexacyanoferrate (II), KFe(Fe(CN)6) and wheat straw ash, as the desulfurization agents. Effect of temperature, particle size and stirring time on desulfurization from the coal samples has been investigated. The temperature and stirring time are the most important parameters for the yield of desulfurization of organic sulfur. Removal of organic sulfur content increased continuously with increasing temperature from 298 to 368 K for potassium ferric hexacyanoferrate (II), and from 350 t0 600 K for wheat straw ash. The organic sulfur removal rate sharply increases from 10 min to 25 min stirring time. After 30 min it reaches a value of plateau. Particle size between-100 mesh and -200 mesh slightly affects on the amount of organic sulfur removal. Maximum removed sulfur values were 23.4% at 368 K for potassium ferric hexacyanoferrate (II) method and 38.2% at 600 K for wheat straw ash method. The wheat straw ash method was more effective than potassium ferric hexacyanoferrate (II) method. 29 refs., 6 figs., 3 tabs.

Demirbas, Ayhan; Karslioglu, Selami [Selcuk University, Konya (Turkey). Dept. of Chemical Engineering

2004-07-01

374

Heavy metal leaching from coal fly ash amended container substrates during Syngonium production  

Energy Technology Data Exchange (ETDEWEB)

Coal fly ash has been proposed to be an alternative to lime amendment and a nutrient source of container substrates for ornamental plant production. A great concern over this proposed beneficial use, however, is the potential contamination of surface and ground water by heavy metals. In this study, three fly ashes collected from Florida, Michigan, and North Carolina and a commercial dolomite were amended in a basal substrate. The formulated substrates were used to produce Syngonium podophyllum Schott 'Berry Allusion' in 15-cm diameter containers in a shaded greenhouse. Leachates from the containers were collected during the entire six months of plant production and analyzed for heavy metal concentrations. There were no detectable As, Cr, Hg, Pb, and Se in the leachates; Cd and Mo were only detected in few leachate samples. The metals constantly detected were Cu, Mn, Ni, and Zn. The total amounts of Cu, Mn, Ni, and Zn leached during the six-month production period were 95, 210, 44, and 337 {mu} g per container, indicating that such amounts in leachates may contribute little to contamination of surface and ground water. In addition, plant growth indices and fresh and dry weights of S. podophyllum 'Berry Allusion' produced from fly ash and dolomite-amended substrates were comparable except for the plants produced from the substrate amended with fly ash collected from Michigan which had reduced growth indices and fresh and dry weights. Thus, selected fly ashes can be alternatives to commercial dolomites as amendments to container substrates for ornamental plant production. The use of fly ashes as container substrate amendments should represent a new market for the beneficial use of this coal combustion byproduct.

Li, Q.S.; Chen, J.J.; Li, Y.C. [University of Florida, Apopka, FL (United States)

2008-02-15

375

Metal accumulation and health effects in raccoons (Procyon lotor) associated with coal fly ash exposure.  

Science.gov (United States)

Approximately 5.4 million cubic yards of coal fly ash and water spilled into the Emory River embayment of Watts Bar Reservoir in east Tennessee on Dec 22, 2008. Raccoons were collected in 2009 and 2010 from the spill site (10/y) and unexposed areas (5/y) to determine whether metals and metalloids were accumulating in raccoons and if any negative health effects resulted from exposure to the spilled coal fly ash. Tissues were analyzed from each animal to determine the concentrations of 26 metals/metalloids. Complete blood cell counts (CBC), plasma biochemistry panels, and histopathology of select tissues also were performed. Results were analyzed by year and exposure status. Although significant differences were present in some tissues for some metals/metalloids, only arsenic in hair, iron in muscle, nickel in hair, selenium in hair and muscle, strontium in hair, and vanadium in hair and liver were increased in spill site animals (one or both years) compared with unexposed animals. No clinically important differences were observed between groups regarding CBC or plasma biochemistry analyses. Lesions were observed on histopathology in some tissues, but there was no difference in the prevalence of lesions between spill site and unexposed animals. There does not seem to be any important accumulation of metals/metalloids or negative health effects in raccoons associated with exposure to coal fly ash compared with unexposed animals. PMID:23292273

Souza, Marcy J; Ramsay, Edward C; Donnell, Robert L

2013-05-01

376

The Character of Dual Site Adsorbent on Coal Fly Ash Toward Benzene Adsorption  

Directory of Open Access Journals (Sweden)

Full Text Available Large quantities of coal fly ash (CFA are produced during combustion of coal in the production of electricity. Most of this ash has not been widely used. CFA is mainly composed of some oxides including Al2O3 and SiO2 having active site and unburnedcarbon as a mesopore that enables it to act as a dual site adsorbent. To get different characters of dual site, CFA was sieved using 150 mesh size, heated at 400oC and reactedwith sodium hydroxide solution. Furthermore, CFA was used as adsorbent of benzene in aqueous solutions. Equilibrium data were evaluated by single site and dual site isotherm models. It can be concluded that single site model yielded excellent fit with equilibrium data of benzene. The values of maximum concentration of adsorbate in solid surface (C?m and Langmuir constant (KL are affected by [Si+Al]/C ratio in CFA. The increase of [Si+Al]/C ratio causes a decrease of qm and KL values.Keywords : coal fly ash, adsorption, benzene

Widi Astuti

2014-10-01

377

Bibliographic review on organic compounds in coal ash; Etude bibliographique sur les composes organiques dans les cendres de charbon  

Energy Technology Data Exchange (ETDEWEB)

Production of ash by conventional fossil-fuel power plants is more closely watched by plant operators, due to the increase environmental regulatory constraints. A number of studies have been conducted in recent years to improve understanding of the physical and chemical characteristics of ash in relation to the fuels, equipment and operating conditions of the plants. The purpose of this study was to establish a bibliographical summary of the various families of organic compounds found in coal ash, and on their concentrations, their conditions of formation and adsorption on ash and their possible impact on the environment. In particular, we examined pollutants targeted by current regulations or regulations now being drawn up with respect to combustion installations. The study revealed the presence of a high number of organic compounds in coal ash. Many aliphatics, monocyclic aromatics and carbonyls are found, as well as heavier compounds which have become a matter of concern to scientists and public authorities in recent years because of their toxicity: polycyclic aromatic hydrocarbons (PAHs) and dioxins and furans (PCDDs and PCDFs). Their generally low concentrations can vary from a few pg/g to several dozen {mu}g/g. Among these compounds, dioxins and furans are found in the lowest concentrations, close to the thresholds of detection (pg/g). PAHs, most of which are non-carcinogenic, are normally found in concentrations from a few ng/g to a few hundred ng/g in the case of fly ash. These concentrations are often lower than those found in the ground and in fly ash from municipal incinerators. Furthermore coal bottom ash contains PAH concentrations which can exceed those found in coal fly ash by 2 orders of magnitude. It is difficult to analyze the environmental impact of such compounds, due to the lack of data on leaching. Most often, the authors agree that the risk that the organic compounds in coal ash will endanger the environmental are limited. (author) 58 refs.

Soreau, S.

1996-12-31

378

Development of Natural Alkalinity in Appalachian Deep Coal Mine Discharges, Irwin Syncline, Pennsylvania, USA  

Science.gov (United States)

Geochemical processes in flooded underground coal mine complexes are controlled by the relationship between overburden mineralogy and the hydrogeologic system, which is influenced by mining methodology and discharge location. Numerous large flow (over 2,000 L/min), historically acidic, deep mine discharges in Appalachian bituminous coal basins are now net alkaline, with circumneutral pH and high concentrations of dissolved iron (20-80 ppm) and sodium (100-500 ppm) [1]. Understanding natural alkalinity production offers alternative approaches for neutralizing acid mine drainage (AMD) and has implications for predictive models, mining regulations, mine discharge remediation, and resource recovery. To determine the subsurface processes involved in the generation of natural alkalinity, we focused on the Irwin syncline, a 240 sq.-km bituminous coal basin in southwestern Pennsylvania. All major streams that arise within or cross the syncline are affected by polluted mine drainage. The pollution ranges from highly acidic iron- and aluminum-contaminated discharges in the northern portion of the basin to highly alkaline, iron and sulfate-contaminated discharges in the southern portion. Underground mine barrier data were used to divide the basin into six hydraulically related sub-basins; mine waters were collected from nine discharges across the basin [2]. Sub-basin hydrology was integrated with infiltration, discharge, and overburden geochemistry and mineralogy. Modeling of Irwin syncline flows using a solute modeling program (PHREEQC 2.4.2; [3]) indicates that the spatial and temporal change in mine water chemistry involves processes other than simple carbonate dissolution or dilution with uncontaminated water. Results indicate that the acidic discharges in the northeastern end of the basin are the product of surface water modified by pyrite oxidation and dissolution of aluminosilicate minerals. Sodium concentrations in those flows are likely the result of minor halite dissolution. The discharges in the southwestern sub-basins, however, exhibit a significant excess of sodium relative to chloride that correlates with increasing alkalinity. Modeling results are consistent with the development of net alkaline waters as a result of limestone dissolution enhanced by subsurface cation exchange reactions with coal overburden clay minerals such as illite, montmorillonite and kaolinite. The data suggest these processes occur in deeper sub-basins (overburden thickness greater than 100 m), dominated by groundwaters derived from neighboring mine pools with minimum infiltration of surface waters; this is corroborated by calculated infiltration rates for these sub-basins. [1]Weaver, T. J., Capo, R.C., Hedin, R. S., 1997, Geol. Soc. Am. Abstr. Prog., v. 29, A-321. [2]Winters, W.R., Capo, R.C., Wolinsky, M.W., Weaver, T.J., Hedin, R.S., 1999, Proc. 16th Ann. Int. Pittsburgh Coal Conf., sect. 6-5, p. 1-36. [3]Parkhurst, D.L. and Appelo, C.A.J., 1999, USGS Water Res. Invest. Rept. 99-4259, 326 p.

Bryant, E. M.; Winters, W. R.; Winters, W. R.; Capo, R. C.

2001-12-01

379

Characterisation of coal ashes with respect to slagging in steam plants; Charakterisierung von Kohlenaschen hinsichtlich ihrer Verschlackung in Dampferzeugern  

Energy Technology Data Exchange (ETDEWEB)

For a long time characterisation of coals with respect to their slagging and fouling tendency has been based on parameters that refer to chemical ash composition. These parameters are imprecise when trying to predict the behaviour of unknown coals. A VGB working group tried to extend these parameters by adding boiler parameters thus improving accuracy. No sustainable results have been available yet. (orig.)

Bonn, Bernhard [FuelConsult GmbH, Essen (Germany)

2010-07-01

380

A flat premixed flame reactor to study nano-ash formation during high temperature pulverized coal combustion and oxygen firing  

Energy Technology Data Exchange (ETDEWEB)

This paper deals with the development of a laboratory reactor to study ultrafine (D {lt} 100 nm) and nano (D {lt} 30 nm) ash formation during pulverized coal combustion and oxy-firing. The reactor consists of an atmospheric pressure flat laminar premixed flame homogeneously doped with pulverized coal particles, monodisperse in size. It is accessible to diagnostics and sampling systems and it allows investigating the early stage of particle formation in a wide range of pulverized coal combustion operative conditions, in terms of gas composition and temperature. Coal combustion in an oxygen enriched gas mixture was investigated by performing on-line high resolution differential mobility analyses (DMA) and thermophoretic samplings for atomic force microscopy (AFM) image analyses. Ultrafine particle size distribution functions in a size range extending down to 1 nm have been measured. Three types of high volatile bituminous coals have been tested. Ultrafine particles, commonly neglected at the exhaust of pulverized coal combustors, form with huge number concentration and they represent a not negligible fraction of total ashes also in volume/mass. Nano-ashes are the most abundant in number and they also significantly contribute to ultrafine particle mass concentration. This not negligible contribution slight increases with the coal chlorine content while the shape of the nano-ash size distribution function is quite unaffected by the used coal type. 22 refs., 6 figs., 1 tab.

Francesco Carbone; Federico Beretta; Andrea D' Anna [Istituto di Ricerche sulla Combustione, Napoli (Italy)

2011-01-15

381

Some considerations relating to the prediction of the efficiency of radiometric methods for the continuous ash content determination of coal  

Energy Technology Data Exchange (ETDEWEB)

For the on-stream determination of the ash content of coal mainly radiometric methods based on the transmission, scatter-transmission or backscattering of high energy X-rays (40 to 60 keV) are proposed. These methods are sensitive to variations of the mass attenuation coefficient and the density of the coal. 12 references.

Thuemmel, H.W.

1983-06-01

382

Fast neutron activation analysis of bulk coal samples for alumina, silica and ash  

International Nuclear Information System (INIS)

The fast neutron activation technique was applied to bulk samples (approximately 11 kg) of Australian black coal. The determination of alumina is based on the reaction 27Al(n,p)27Mg by counting the 0.844-MeV peak (tsub(1/2) = 9.4 min). Silica is determined by means of the reaction 28Si(n,p)28Al; the 1.78-MeV peak (tsub(1/2) = 2.3 min) is counted and a correction for the interference from alumina is applied. The ash content is based on the correlation between ash and the sum of alumina and silica. The accuracies (1 SD) for the determination of alumina, silica and ash were 0.52% Al2O3, 0.79% SiO2 and 1.02% ash, respectively. The ash, alumina and silica contents of the samples were in the ranges 8.8-37.5%, 1.3-10.3% and 6.4-22%, respectively. (Auth.)

383

Application of high-fluidity concrete containing ashes from overseas coal; Kaigaitanbai wo mochiita koryudo concrete no seko  

Energy Technology Data Exchange (ETDEWEB)

Oita LNG Co. built in 1991 a breakwater for its No.4 LNG tank, in which high-fluidity concrete containing coal ashes as the admixture is used. Subsequently, high-fluidity concrete was massively used for a breakwater for its No.5 LNG tank, where a large quantity of concrete, around 5,400m{sup 3}, was placed for an extended period of 6 months. The concrete contains size-classified fly ashes from overseas coal as the admixture, for effective utilization of coal ashes, manpower saving for solidification works and improvement of working environments. This paper describes the high-fluidity concrete, containing EP ashes as the size-classified fly ashes from 3 types of overseas coal, and its application. It comprises Portland blast-furnace cement (type B), fine and coarse sand particles as the fine aggregate, pulverized limestone as the coarse aggregate, a high-functional, polycarboxylate-based AE water-reducing agent as the admixture, and a special AE water-reducing agent for fly ashes; 300kg of fly ashes and 200kg of cement for 1m{sup 3} of concrete. The concrete has a compressive strength of 38 to 45N/mm{sup 2}, after it is placed. It is less expensive than the ordinary concrete. 2 refs., 11 figs., 6 tabs.

Hirano, T.; Hata, S. [Kyushu Electric Power Co. Inc., Fukuoka (Japan); Shinpuku, C.

1998-03-05

384

Leaching characteristics of coal and fly ash from Parichha Thermal Power Plant, Jhansi, U.P. (India)  

International Nuclear Information System (INIS)

Nearly 73% of India's total installed power generation capacity is thermal based power plants, 90% of its coal-based thermal power plants. Coal-based thermal power plants produce approximately 100 million tones of fly ash annually. Indian coal is of poor quality with high ash contents (35-50%) and low calorific value (? 15 MJ/Kg). This results in higher coal consumption for each MW power. Power generation in India has increased 1362 MW in 1947 to about 1,38,251 MW in March 2009. India is worlds sixth largest energy consumer, accounting for 3.4% of global energy consumption. More than 80 Coal-based thermal power plants is producing 73,492.38 MW (53.15%) while 14,581.71 MW(10.54%) by Gas-based thermal power plants, 1,201.75 MW (0.069%) by Diesel-based thermal power plants, 10,175 MW (7.35%) by Wind power, 34,680.76 MW (25.08%) by Hydroelectric power and 4,120 MW (2.90%) by Nuclear power reactors. The use of coal in power generation has led to increasing environmental problems associated not only with gaseous emissions but also with the disposal of ash residues. In particular, the use of low quality coals with high ash content results in huge quantities of both fly ash and bottom ash to be disposed off. An important problem related to coal ash disposal is the heavy metal content of the residue. In this regard, experimental results of numerous studies indicate that toxic trace metals may leach when coal and fly ash come into contact with water. In this study, coal and fct with water. In this study, coal and fly ash samples obtained from Parichha Thermal Power plant, located about 25 km from Jhansi at Parichha in Jhansi of Uttar Pradesh, and were subjected to toxicity tests, namely, Toxicity Characteristic Leaching