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1

Biological activity of coal alkaline ashes  

Energy Technology Data Exchange (ETDEWEB)

This paper discusses the results of tests of the biological activity of ashes produced by combustion of brown coals in the Konin power station and black coal in the Halemba power station. Possibility of agricultural use of ash from ash spoil banks of the power stations is analyzed. Mustard plant (sinapis alba) was sown in ash samples. Plant growth was observed as well as quantitative and qualitative growth of bacteria in the soil. The tests show that the biological activity of alkaline ashes is generally low. The biological activity of brown coal ash is higher than that of black coal ash. Addition of peat increases the biological activity of ash. Green manure can both negatively and positively influence the biological activity of ash: in the case of ashes from Konin the influence is negative, and in the case of Halemba ash the influence is positive. Adding soil rich in organic matter is superior to adding peat or green manure. On the basis of tests recommendations are formulated on using power station ash with the aim of reducing the negative environmental effect of ash spoil banks. (3 refs.) (In Polish)

Krezel, Z.; Krezel, R.; Wysocki, W.

1978-01-01

2

Uptake of arsenic by alkaline soils near alkaline coal fly ash disposal facilities.  

Science.gov (United States)

The attenuation of arsenic in groundwater near alkaline coal fly ash disposal facilities was evaluated by determining the uptake of arsenic from ash leachates by surrounding alkaline soils. Ten different alkaline soils near a retired coal fly ash impoundment were used in this study with pH ranging from 7.6 to 9.0, while representative coal fly ash samples from two different locations in the coal fly ash impoundment were used to produce two alkaline ash leachates with pH 7.4 and 8.2. The arsenic found in the ash leachates was present as arsenate [As(V)]. Adsorption isotherm experiments were carried out to determine the adsorption parameters required for predicting the uptake of arsenic from the ash leachates. For all soils and leachates, the adsorption of arsenic followed the Langmuir and Freundlich equations, indicative of the favorable adsorption of arsenic from leachates onto all soils. The uptake of arsenic was evaluated as a function of ash leachate characteristics and the soil components. The uptake of arsenic from alkaline ash leachates, which occurred mainly as calcium hydrogen arsenate, increased with increasing clay fraction of soil and with increasing soil organic matter of the alkaline soils. Appreciable uptake of arsenic from alkaline ash leachates with different pH and arsenic concentration was observed for the alkaline soils, thus attenuating the contamination of groundwater downstream of the retired coal fly ash impoundment. PMID:23877575

Khodadoust, Amid P; Theis, Thomas L; Murarka, Ishwar P; Naithani, Pratibha; Babaeivelni, Kamel

2013-12-01

3

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.

4

Arsenic concentration in porewater of an alkaline coal ash disposal site: Roles of siderite precipitation/dissolution and soil cover  

Energy Technology Data Exchange (ETDEWEB)

The geochemical behavior of As in porewaters of an alkaline coal ash disposal site was investigated using multilevel samplers. The disposal site was in operation from 1983 until 1994 and was covered with 0.3-0.5 m thick soils in 2001 when this study was initiated. Sequential extraction analyses and batch leaching experiments were also performed using the coal ash samples collected from the disposal site. The results suggest the important roles of siderite (FeCO{sub 3}) precipitation/dissolution and soil cover, which have been ignored previously. Arsenic levels in the porewater were very low (average of 10 {mu} g L{sup -1}) when the site was covered with soil due to coprecipitation with siderite. The soil cover enabled the creation of anoxic conditions, which raised the Fe concentration by the reductive dissolution of Fe-(hydr)oxides. Because of the high alkalinity generated from the alkaline coal ash, even a small increase in the Fe concentration (0.66 mg L{sup -1} on average) could cause siderite precipitation. When the soil cover was removed. however, an oxidizing condition was created and triggered the precipitation of dissolved Fe as (hydr)oxides. As a result, the dissolution of previously precipitated As-rich siderite caused higher As concentration in the porewater (average of 345 {mu} g L{sup -1}).

Kim, K.; Park, S.M.; Kim, J.; Kim, S.H.; Kim, Y.; Moon, J.T.; Hwang, G.S.; Cha, W.S. [Kunsan National University, Jeonbuk (Republic of Korea). Dept. of Environmental Engineering

2009-09-15

5

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

Energy Technology Data Exchange (ETDEWEB)

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 C 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 ({sup 13}C NMR) tests on the product of the hydrothermal upgrading and demineralization process. (author)

Mursito, Anggoro Tri [Research Centre for Geotechnology, Indonesian Institute of Sciences (LIPI), Jl. Sangkuriang Komplek LIPI, Gd. 70, Bandung 40135 (Indonesia); Department of Earth Resources Engineering, Graduate School of Engineering, Kyushu University, 744 Motooka, Nishiku, Fukuoka 819-0395 (Japan); Hirajima, Tsuyoshi; Sasaki, Keiko [Department of Earth Resources Engineering, Faculty of Engineering, Kyushu University, 744 Motooka, Nishiku, Fukuoka 819-0395 (Japan)

2011-01-15

6

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.

7

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

8

Processes controlling the variations of pH, alkalinity, and CO2 partial pressure in the porewater of coal ash disposal site  

International Nuclear Information System (INIS)

Alkalinity, pH, and pCO2 are generally regarded as the most important parameters affecting trace element leaching from coal ashes. However, little is known about how those parameters are actually regulated in the field condition. This study investigated the processes controlling those parameters by observing undisturbed porewater chemistry in a closed ash disposal site. The site is now covered with 30-50 cm thick soils according to the management scheme suggested by the Waste Management Law of Korea and our results show the important role of soil cover regulating those parameters in the shallow porewater. Without the soil cover, the shallow porewater shows low pCO2 and alkalinity, and highly alkaline pH. In contrast, the porewater shows much higher alkalinity and near neutral pH range when the site was covered with the low permeability soils. This difference was caused by the CO2 supply condition changes associated with the changes in infiltration rate. The geochemical modeling shows that the calcite precipitations induced by porewater aging, dolomitization, and weathering of solid phases are the main processes controlling alkalinity, pH, and pCO2 in the deep saline porewaters. The weathering of coal ash plays the most important role decreasing the alkalinity in the deep porewater.

9

Identifying mechanisms for the mobilization and attenuation of elemental constituents from weathered alkaline coal ash using geochemical modeling  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Nearly 70% of coal combustion products (CCPs) produced annually in the United States (110 million tons in 2001) are disposed of in saturated ash impoundments or ash landfills. The large volume of disposed CCPs and their potential to leach toxic trace metals (e.g., As, Se, Hg, Pb, and Cr) at concentrations above established groundwater quality standards is a major concern. A large amount of empirical data is available pertaining to the effects of CCPs on water quality; however, only relatively...

Burns, Perre Edmon

2003-01-01

10

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

11

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

12

Coal ash artificial reef demonstration  

International Nuclear Information System (INIS)

This experimental project evaluated the use of coal ash to construct artificial reefs. An artificial reef consisting of approximately 33 tons of cement-stabilized coal ash blocks was constructed in approximately 20 feet of water in the Gulf of Mexico approximately 9.3 miles west of Cedar Key, Florida. The project objectives were: (1) demonstrate that a durable coal ash/cement block can be manufactured by commercial block-making machines for use in artificial reefs, and (2) evaluate the possibility that a physically stable and environmentally acceptable coal ash/cement block reef can be constructed as a means of expanding recreational and commercial fisheries. The reef was constructed in February 1988 and biological surveys were made at monthly intervals from May 1988 to April 1989. The project provided information regarding: Development of an optimum design mix, block production and reef construction, chemical composition of block leachate, biological colonization of the reef, potential concentration of metals in the food web associated with the reef, acute bioassays (96-hour LC50). The Cedar Key reef was found to be a habitat that was associated with a relatively rich assemblage of plants and animals. The reef did not appear to be a major source of heavy metals to species at various levels of biological organization. GAI Consultants, Inc (GAI) of Monroeville, Pennsylvania was the prime consultant for the project. The biological monitoring surveys and evaluhe biological monitoring surveys and evaluations were performed by Environmental Planning and Analysis, Inc. of Tallahassee, Florida. The chemical analyses of biological organisms and bioassay elutriates were performed by Savannah Laboratories of Tallahassee, Florida. Florida Power Corporation of St. Petersburg, Florida sponsored the project and supplied ash from their Crystal River Energy Complex

13

Evaluation of leachates from coal refuse blended with fly ash at different rates  

Energy Technology Data Exchange (ETDEWEB)

There is good interest in returning coal combustion products to mining sites for beneficial reuse as liming agents. A column study examined the effects of blending two coal fly ashes with an acid-forming coal refuse (4% pyritic S). Refuse was from a coal preparation plant cleaning coal from the Pearless seam of the upper Pennsylvanian system. Both fly ashes were net alkaline, but had relatively low neutralizing capacities. One ash with moderate alkalinity (CRF) was bulk blended with coal refuse at 0, 20, and 33% (w/w), while another lower alkalinity ash (WVF) was blended at 0, 5, 10, 20 and 33% (w/w). The columns were leached (unsaturated) weekly with 25 cm of simulated precipitations for {gt} 150 wk. Where high amounts of ash alkalinity ({gt} 20% w/w) were mixed with the coal refuse, pyrite oxidation was controlled and leachate pH was {gt} 7.0 with low metal levels throughout the study. At lower rates of alkalinity loading, trace metals were sequentially released from the WVF ash as the 5, 10 and 20% treatments acidified due to pyrite oxidation. Leachate metals increased in proportion to the total amounts applied in the ash. In this strongly acidic environment, metals such as Mn, Fe and Cu were dissolved and leached from the ash matrix in large quantities. If ash is to be beneficially reused in the reclamation of acid-producing coal refuse, the alkalinity and potential acidity of the materials must be balanced through the appropriate addition of lime or other alkaline materials to the blend. Highly potentially acidic refuse materials, such as that used here, may not be suitable for ash/refuse codisposal scenarios. 35 refs., 7 figs., 2 tabs.

Stewart, B.R.; Daniels, W.L.; Zelazny, L.W.; Jackson, M.L. [Mississippi State University, MS (USA). Dept. of Plant and Soil Science

2001-08-01

14

Laboratory coal ash corrosion tests  

Energy Technology Data Exchange (ETDEWEB)

In a program to provide complete, reliable corrosion data for selected superheater and reheater tube alloys, Ishikawajima-Harima Heavy Industries Co., Ltd., Tokyo, Japan, conducted materials tests in simulated coal-ash environments. Test coupons were made from 11 base alloys, 7 cladding alloys (typically for coextruded tubes), chromizings, plasma spray coatings, and weld metals. The coupons were coated with synthetic ashes mirroring actual deposits and were exposed to synthetic gas containing sulfur dioxide, oxygen, carbon dioxide, water, and nitrogen. They were exposed for 100 hours at 600 to 750/degree/C (1112 to 1382/degree/F) and then were weighed to determine metal loss. Based on the results of testing, three commercial alloys (Alloy 800H, HR3C, and Tempaloy CR30A) as single-walled tubes and Type 310SS and 35Cr-45Ni as clad or co-extruded tubes are recommended for aggressive, corrosive atmospheres. However, co-extruded tubes are expensive; thus there is an economic advantage to using HR3C and Alloy 800H in the corrosive atmospheres encountered in Phases 0 and 1. Materials are discussed for these advanced boilers as well as for boilers currently experiencing coal-ash corrosion.

Wolowodiuk, W.

1989-07-01

15

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)

16

Ash phases in Australian brown coals  

Energy Technology Data Exchange (ETDEWEB)

The phases present in coal ash determine the ash fusion temperature and hence the fouling propensity of the ash. The ash phases are difficult to predict from the chemical analyses of either the coal or the ash. The problem is complex because there are typically eight elements present which form oxides or mixed oxides, namely aluminium, iron, calcium, magnesium, sodium, potassium, titanium, and silicon, and in addition there are also appreciable amounts of sulfate and often chloride present. The majority of the metal ions are initially present as inorganic matter in the coal, with some pyrite, silica or various aluminosilicates constituting the mineral part. This paper aims at the logical development of a method for predicting ash phases starting from the phase analysis of the initial coal and the elemental analysis of the ash. These results are then compared with the available phase analyses of the ashes. It was shown that a simple model based on the chemical activity of the various constituents in brown coal ash provides a very good prediction of the production of calcium aluminoferrite in precipitator ashes as a fraction of the total iron phases. (author). 1 tab., 1 fig., 6 refs.

Cashion, J.D.; Brown, L.J. [Monash Univ., Clayton, VIC (Australia). Dept. of Physics

1997-04-01

17

Submicron ash formation from coal combustion  

Energy Technology Data Exchange (ETDEWEB)

In recent years, fine particles have been found to be the cause of various harmful effects on health, and many countries have imposed restrictions on emission of these particles. Fine ash particles are formed during coal combustion in power stations and, if not collected in the air pollution control devices, are emitted into the atmosphere. The fine ash particles can remain airborne for long periods and can result in deleterious health effects when inhaled and deposited in the lungs. Previous studies have shown that combustion of coals of different rank can result in differences in the amount and chemistry of the submicron ash particles. This study examines the variability occurring between the submicron ashes formed from coals of similar rank. Five Australian bituminous coals were burned in a laminar flow drop tube furnace in two different oxygen environments to determine the amount and composition of submicron ash formed. The experimental setup is described and the repeatability of the experiments is discussed. The variability in the submicron ash yield as a percentage of the total ash collected and the submicron ash composition are presented and discussed. This paper presents experimental results rather than a detailed discussion on its interpretation. However, the results indicate that the condensation of evaporated species is responsible for the formation of ash particles smaller than 0.3 {mu}m.36 refs., 5 figs., 6 tabs.

B.J.P. Buhre; J.T. Hinkley; R.P. Gupta; T.F. Wall; P.F. Nelson [University of Newcastle, Callaghan, NSW (Australia). Cooperative Research Centre for Coal in Sustainable Development, Department of Chemical Engineering

2005-07-01

18

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

19

Elemental analysis of coal and coal ASH by PIXE technique  

Energy Technology Data Exchange (ETDEWEB)

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: Black-Right-Pointing-Pointer Elemental analysis of coal and coal ash including pond ash is the first of its kind. Black-Right-Pointing-Pointer The enrichment ratio has been exclusively explained in the study. Black-Right-Pointing-Pointer Non-destructive PIXE analysis has been employed in this study and both major and trace elements has been estimated.

Patra, K.C. [Dept. of Physics, Sambalpur University, Jyoti Vihar, Burla (India); Institute of Physics, Sachivalaya Marg, Bhubaneswar - 751005 (India); Rautray, Tapash R., E-mail: tapash.rautray@gmail.com [Institute of Physics, Sachivalaya Marg, Bhubaneswar - 751005 (India); Centre of Excellence in Theoretical and Math Sciences, SOA University, Bhubaneswar - 751030 (India); Tripathy, B.B. [Dept. of Physics, Silicon Institute of Technology, Patia, Bhubaneswar - 751024 (India); Nayak, P. [Dept. of Physics, Sambalpur University, Jyoti Vihar, Burla (India)

2012-04-15

20

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.

 
 
 
 
21

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...

22

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

23

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

24

Fundamental study on a coal ash neutralizing technology; Sekitanbai chuwa shori gijutsu kiso kenkyu  

Energy Technology Data Exchange (ETDEWEB)

The main constituents of coal ash are silica and alumina accounting for 70%, and the remaining constituents contain calcium at about 5%. When coal ash contacts with water, the water presents strong alkalinity. The prevention thereof, if possible at all, is effective for ash use in land reclamation, more effective utilization, and environment preservation. When water is sprayed into coal combustion waste gas, a neutralization phenomenon occurs to reduce pH of the recovered coal ash. This has been proposed in the wet-type desulfurization method using limestone, which is explained as follows: adsorption of water into coal ash surface occurs first, then SO2 in the waste gas is dissolved into this adsorbed water, and finally reacts with calcium on the coal ash surface, producing CaSO{sub 4} and CaSO{sub 3}. However, the pH calculated from the ion balance in a sample ash liquation test does not strictly agree with the measurement value. Since infiltration of sulfur compounds into coal ash particles is not recognized in all of the samples, factors other than dissolution of SO2, for example structural change in the ash particle surface due to existence of the adsorbed water can neither be ignored. (NEDO)

Tsuchiai, H.; Hayasaka, K.; Miyagawa, M. [Hokkaido Electric Power Co. Inc., Sapporo (Japan)

2000-03-24

25

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

26

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

27

Elemental analysis of coal and coal ASH by PIXE technique.  

Science.gov (United States)

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. PMID:22204786

Patra, K C; Rautray, Tapash R; Tripathy, B B; Nayak, P

2012-04-01

28

Characterization of fly ash from coal combustion  

Energy Technology Data Exchange (ETDEWEB)

Fly ash derived from coal combustion contains predominantly spherical particles which consist of an insoluble aluminosilicate glass containing several mineral impurities. An outer layer, 50 to 300 A thick, is rich in many potentially toxic trace elements in the form of simple and complex sulfates. This layer, which is soluble in water, contains essentially all of the particulate sulfur present in fly ash in the form of sulfate. The actual mechanism(s) of formation of particulate sulfate salts are ill-defined but probably involve adsorption of condensation of gaseous sulfur species onto fly ash surfaces within the power plant stack system.

Natusch, D. F.S.

1978-01-01

29

Synthesis of zeolites from coal fly ash  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

30

Immobilization of cesium in alkaline activated fly ash matrix  

International Nuclear Information System (INIS)

The immobilization potential of alkaline activated fly ash (AAFA) matrices for cesium has been investigated. The presence of Cs in the AAFA pastes, prepared using 8M NaOH solution as activator, showed no significant adverse effects on mechanical strength or microstructure, nor were significant quantities of Cs leached following application of the Toxic Characteristic Leaching Procedure (TCLP) and American Nuclear Society (ANS) 16.1 leaching protocols. Microstructural analysis shows Cs associated with the main reaction product in the AAFA suggesting that cesium is chemically bound rather than physically encapsulated. It is proposed that cesium is incorporated into the alkaline aluminosilicate gel, a precursor for zeolite formation

31

Characterization of sintered coal fly ashes  

Energy Technology Data Exchange (ETDEWEB)

Can, Catalagzi, Seyitomer and Afsin-Elbistan thermal power plant fly ashes were used to investigate the sintering behavior of fly ashes. For this purpose, coal fly ash samples were sintered to form ceramic materials without the addition of any inorganic additives or organic binders. In sample preparation, 1.5 g of fly ash was mixed in a mortar with water. Fly ash samples were uniaxially pressed at 40 MPa to achieve a reasonable strength. The powder compacts were sintered in air. X-ray diffraction analysis revealed that quartz (SiO{sub 2}), mullite (Al{sub 6}Si{sub 2}O{sub 13}), anorthite (CaAl{sub 2}Si{sub 2}O{sub 8}), gehlenite (Ca{sub 2}Al{sub 2}SiO{sub 7}) and wollastonite (CaSiO{sub 3}) phases occurred in the sintered samples. Scanning electron microscopy investigations were conducted on the sintered coal fly ash samples to investigate the microstructural evolution of the samples. Different crystalline structures were observed in the sintered samples. The sintered samples were obtained having high density, low water adsorption and porosity values. Higher Al{sub 2}O{sub 3} + SiO{sub 2} contents caused to better properties in the sintered materials. 19 refs., 5 figs., 4 tabs.

M. Erol; S. Kucukbayrak; A. Ersoy-Mericboyu [Istanbul Technical University, Istanbul (Turkey). Department of Chemical Engineering, Chemical and Metallurgical Engineering Faculty

2008-06-15

32

Selenium speciation in coal ash spilled at the Tennessee Valley Authority Kingston site.  

Science.gov (United States)

Selenium (Se) in coal ash spills poses a threat to adjacent ecosystems because of its potential to mobilize and bioaccumulate in aquatic organisms. Given that the mobility and bioavailability of Se is controlled by its valence states, we aimed to define Se speciation in coal ash solids and examine the relationships between Se speciation and the magnitude of its mobilization from coal ash. We used coal ash samples from the Tennessee Valley Authority (TVA)-Kingston fossil plant and the site of a coal ash spill that occurred in 2008 in Tennessee. Results of X-ray absorption spectroscopic analyses showed that Se in coal ash samples was a mixture of elemental Se(0) and Se oxyanions. The amount of leachable Se increased with an increase of pH from 3 to 13. At the natural pH of coal ash samples (from pH 7.6 to 9.5), the leachable Se was comprised of Se oxyanions, mainly selenite. This was observed by both direct quantification of Se oxyanions in the leachate and the corresponding loss of Se oxyanions in the solid phase. At pH 12, however, the Se release appeared to derive from both desorption of Se oxyanions and oxidative dissolution of elemental Se(0). Our results indicate that Se oxyanions are the most labile species; however, the magnitude of Se mobilization will increase if the waste material is subjected to alkaline conditions. PMID:24266628

Liu, Yu-Ting; Chen, Tsan-Yao; Mackebee, William Greer; Ruhl, Laura; Vengosh, Avner; Hsu-Kim, Heileen

2013-12-17

33

Investigation of profiles from coal ash disposal sites  

Energy Technology Data Exchange (ETDEWEB)

Coal ash disposal sites, 2 to 15 years old, have been investigated. Mosses colonialize uncovered sites after about 2 yers when the pH has gone down to 8-9 from the original value of about 11. By the action of CO/sub 2/ in the soil atmosphere, 1-2 percent CaCO/sub 3/ had been formed in the ash from CaO. Leachates from two of the profiles had pH of about 12. Molybdenum and arsenic, both present in form of anions, were found in elevated concentrations. Molybdenum in the ash is enriched in the grass turf on the top of the profile is likely to be leached out in the portion below. Arsenic in the ash is correlated to the contents of Fe/sub 2/O/sub 3/ and the leaching may be controlled by adsorption to ferric hydroxides. Gypsum has most likely been present in the profiles but has been leached out. The carbonatization of CaO is an important process that shortens the alkaline period in the disposal site and than than buffers the leachate at a pH of 8-9. The carbonatization ought to be favoured by means of covering the ash with soil as early as possible.

Jacks, G.

1983-12-01

34

Evaluation of cocomposted coal fly ash on dynamics of microbial populations and heavy metal uptake  

Energy Technology Data Exchange (ETDEWEB)

Vicia faba, in a pot experiment with sandy and clayey soils under greenhouse conditions, was checked for growth response to different amendments with coal alkaline fly ash or cocomposted fly ash mixed with lignocellulosic residues. Soil microbial populations, pH and electrical conductivity as well as heavy metal uptake by plants were monitored. At rates of five and ten percent (on a dry matter basis) in both soils, neither fly ash alone nor cocomposted fly ash exerted any negative effect. Plant biomass production was not influenced in either clayey or sandy soil. Alkaline fly ash did not promote microbial growth when applied alone to the soils. However, cocomposted fly ash generally increased bacterial and actinomycetes counts in both soils. Fungi were not affected by ash. Due to the increase of soil pH by alkaline fly ash or cocomposted fly ash, plant uptake of heavy metals was depressed in the sandy soil. Heavy metal mobility did not cause change in the clayey soil where a high buffering capacity mitigated the effects of fly ash amendments.

Vallini, G.; Vaccari, F.; Pera, A.; Agnolucci, M.; Scatena, S.; Varallo, G. [University of Verona, Verona (Italy). Science and Technology Dept.

1999-06-01

35

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

36

Solubility and transport of arsenic coal ash  

International Nuclear Information System (INIS)

An experimental method combined with a numerical model allows a comparison of two methods for the disposal of ash that contains arsenic, from the Rio Escondido coal-fired power plant. The calculation yields significant differences in aquifer migration times for the site. The wet disposal method gave 10 years time and the dry method gave 22 years. Experiments were performed on the rate of dissolution of the arsenic from ash samples; and these results indicate a first order kinetics reaction. 8 refs., 8 figs., 8 tabs

37

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

38

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

39

A comparison study of ash formation during pilot-scale combustion of pulverized coal and coal-water slurry fuels  

Energy Technology Data Exchange (ETDEWEB)

The objective of this study was to investigate the effect of fuel form. specifically pulverized coal and coal-water slurry fuel (CWSF), on the particle size distribution (PSD) and inorganic composition of the ash formed during combustion. Three areas of primary interest were fuel particle and droplet size distribution, mineral matter PSD, and the composition and occurrence of inorganics in the fuel. The reactions of pyrite, silicates, aluminosilicates, and alkali and alkaline earth elements during combustion are traced. Two coals, a West Virginia Elk Creek high volatile A bituminous coal and the North Dakota Beulah lignite, were fired as a standard utility grind pulverized fuel and a CWSF at 316.2 MJ/h at 20% excess air in the Penn State Combustion Laboratory down-fired combustor. Fuel PSD and droplet size distribution of the pulverized coal and CWSF are important in determining the PSD of the respective ash when the PSD of the mineral matter and the composition and occurrence of the inorganics in the two fuels are similar, as in the case of the Elk Creek fuels. The mechanism for ash formation in both Elk Creek fuels was coalescence and agglomeration of the inorganics in the coal. The Elk Creek CWSF ash was coarser than the pulverized coal ash due to the larger CWSF char size formed during atomization. The average diameter of the inorganic particles identified in the pulverized coal ash was 2.6 times smaller than those identified in the fuel. The mechanism for ash formation in the Beulah CWSF was coalescence and agglomeration of inherent mineral matter. The average diameter of the inorganic particles identified in the CWSF ash was 3.3 times larger than those identified in the fuel.

Miller, S.F.

1992-01-01

40

Recent advances in recycling clean-coal ash  

Energy Technology Data Exchange (ETDEWEB)

Clean coal ashes obtained from coal-fired power stations equipped with FBC boilers and control technologies for SOx and NOx are currently under-utilized. This paper presents the laboratory results of a project to develop mixtures of controlled low strength material (CLSM) using such ashes. The laboratory study made use of ash from the North and South Silos at the Manitowoc Public Utilities power station. The primary goal of this study was to find high-volume applications for cement-based products using waste ashes from the combustion of high-sulfur coals. The two phases of the project were described. Fifteen coal ash samples from 8 different sources were characterized for their physical, chemical, mineralogical and microstructural properties. The study showed that structural-grade concrete could be manufactured using large amounts of conventional or clean-coal ash, blended ashes, high-sulfur coal ashes, or coal ash blends. The paper outlined the use of clean-coal ash as a setting time regulator in Portland cement; high performance materials using Illinois coal combustion by-products (CCP); clean-coal ash as a potential source for defined-performance concrete; use of superplasticizers in the production of high-volume fly ash (HVFA) concrete containing clean-coal ash and class F fly ash; the development of high-carbon CCPs and flue gas desulphurization by-products for roadway base construction; and, the use of flue gas desulphurization material and class F CCP in ready-mixed concrete. 177 refs.

Naik, T.R. [Wisconsin Univ., Milwaukee, WI (United States). Dept. of Civil Engineering and Mechanics

2004-07-01

 
 
 
 
41

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

42

Evaluation of Pollutant Leaching Potential of Coal Ashes for Recycling  

Science.gov (United States)

By 2009, coal ashes produced from coal-based power plants in Korea have been reused as cement supplement materials; however, the rest is mostly disposed in landfills inside the plant properties. Continuous production of coal ashes and limited landfill sites require more recycles of coal ashes as base materials, specifically in constructions of roads and of huge industrial complex. Previous researches showed that coal ashes could contain various metals such as arsenic(As), chromium(Cr), lead(Pb), nickel(Ni), selenium(Se), etc. In this study, we collected four types of bottom ashes and two of fly ashes from four coal-based power plants. These ash samples were tested with distilled water through the column leaching process in oxidized conditions. The column test results were compared with those of total digestion, sequential extraction processes and TCLP. Concentrations of metals in outflows from columns are generally greater in fly ashes than in bottom ashes, specifically for As, Se, B, Sr and SO4. Only one fly ash (J2-F) shows high concentrations of arsenic and selenium in leachate. Sequential extraction results indicate that these metals are in readily soluble forms, such as adsorbed, carbonated, and reducible forms. Results of TCLP analysis indicate no potential contaminants leached from the ashes. In conclusion, recycling of coal combustion ashes could be encouraged with proper tests such as sequential and leaching experiments.

Park, D.; Woo, N. C.; Kim, H.; Yoon, H.; Chung, D.

2011-12-01

43

Surface modification of coal fly ash by sodium lauryl sulphate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Thirty million tons of coal fly ash are produced each year in South Africa of which approximately 5% is utilised beneficially. With the growing concern about pollution and increasing landfill costs, the study of the utilisation and application of coal fly ash has increased worldwide. The morphology and particle size of fly ash make it suitable for application as filler in polymers, but its application is hindered by the lack of compatibility between the inorganic surface of the ash and...

Mathebula, Confidence Lethabo

2013-01-01

44

Characterisation of the glass fraction of a selection of European coal fly ashes  

Energy Technology Data Exchange (ETDEWEB)

Fly ash largely consists of the inorganic content of coal that remains after combustion. The crystalline phases present in fly ash may form upon cooling of a molten alumino-silicate glass. This view is supported by the spherical shape of many fly ash particles, implying that they have gone through a viscous fluid state. The amorphous content in fly ash is believed to dominate reactivity behaviour, under both alkaline and acid conditions, because glasses have a higher potential energy than the equivalent crystal structure and the variation of bond angles and distances in a glass makes the bond breakage easier. It is the degradation behaviour under alkaline conditions, and the subsequent release of silica from the glass phase, that is important in the use of fly ash for conversion to zeolites and for pozzolanic applications in cement. This research comprehensively studies the composition, quantity and stability of the glass phase in a series of nine fly ashes sourced from Spanish and Italian power plants. The quantitative elemental composition of the glass phase in each fly ash was determined. Samples of the ashes then underwent a series of tests to determine the internal structure of the ash particles. Heat treatment of most of the ashes results in mullite crystallising from the glass phase; this is the crystalline phase that is predicated to form by both the relevant phase diagrams and also by NMR spectroscopy. In the ashes, mullite is present as a spherical shell, tracing the outline of the particle but in some specific cases the mullite skeleton is made up of coarse crystals reach also the internal parts of the particles. The morphology and density of the mullite crystals in these shells varies greatly. This work has supported the view that some crystalline phases present in fly ashes, such as mullite, form upon cooling of the amorphous glass melt as opposed to direct conversion from existing mineral phases in the coal during the combustion process.

Henry, J.; Towler, M.R.; Stanton, K.T.; Querol, X.; Moreno, N. [University of Limerick, Limerick (Ireland). Material & Surface Science Institute

2004-05-01

45

Thermomechanical analysis of laboratory ash, combustion ash and deposits from coal combustion  

Energy Technology Data Exchange (ETDEWEB)

Mineral impurities in coal form ash and a part of the fly ash form deposits in pulverized coal-firing furnaces. Understanding of the transformation of mineral matter in coals to flyash and deposit formation has improved knowledge and helped industrial engineers better handle ash-related problems. In Australia, ash fusibility tested in accordance to the standardized procedure or measured by Thermo-Mechanical Analysis (TMA) has been widely used to compare and predict slagging potential of various coals. The current study aims at obtaining an understanding of the sensitivity of TMA analysis to the physical, chemical and morphological properties of coal combustion deposits. In the study combustion residues including ash prepared in a laboratory oven at a temperature of 815 C, flyash collected in a pilot scale furnace and deposits collected from a utility furnace generated from one Australian coal are used for TMA analysis. Ash samples with various levels of iron content were obtained from different milling performance, ash samples with various silicon and alumina contents were prepared by mixing ash with quartz, kaolinite and bauxite. Results indicated that TMA measurements on coal ashes are very sensitive to iron content and can be used to indicate iron related slagging problems in pf-fired boilers. For ash deposits, both the physical properties such as their homogeneous/heterogeneous nature and ash chemistry affect TMA measurement. (author)

Liu, Yinghui; Elliott, Liza; Wall, Terry [Cooperative Research Centre for Coal in Sustainable Development, Department of Chemical Engineering, University of Newcastle, EB Building, Callaghan, NSW 2308 (Australia); Gupta, Rajender [Chemical Engineering, the University of Alberta (Canada); Fujimori, Toshiro [Ishikawajima-Harima Heavy Industries Co., Ltd. (IHI), Tokyo (Japan)

2007-12-15

46

Coal Ash Corrosion Resistant Materials Testing Program  

Energy Technology Data Exchange (ETDEWEB)

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 #1, a 110 MWe unit firing high sulfur Ohio coal. In November 2001 the first section was removed for thorough metallurgical evaluation after 33 months of operation. The second and third sections remain in service and the second is expected to be removed in the fall of 2003; the last is tentatively planned for the fall of 2004. This paper describes the program; its importance; the design, fabrication, installation and operation of the test system; materials utilized; experience to date; and results of the evaluation of the first section.

McDonald, D.K.

2003-04-22

47

Geochemistry of coals, coal ashes and combustion wastes from coal-fired power stations  

International Nuclear Information System (INIS)

Contents, concentration trends, and modes of occurrence of 67 elements in coals, coal ashes, and combustion wastes at eleven Bulgarian thermoelectric power stations (TPS) were studied. A number of trace elements in coal and coal ash have concentrations greater than their respective worldwide average contents (Clarke values). Trace elements are concentrated mainly in the heavy accessory minerals and organic matter in coal. In decreasing order of significance, the trace elements in coal may occur as: element-organic compounds; impurities in the mineral matter; major components in the mineral matter; major and impurity components in the inorganic amorphous matter; and elements in the fluid constituent. A number of trace elements in the waste products, similar to coal ashes, exceed known Clarke contents. Trace elements are mainly enriched in non-magnetic, heavy and fine-grained fractions of fly ash. They are commonly present as impurities in the glass phases, and are included in the crystalline components. Their accessory crystalline phases, element-organic compounds, liquid and gas forms, are of subordinate importance. Some elements from the chalcophile, lithophile and siderophile groups may release into the atmosphere during coal burning. For others, the combustion process appears to be a powerful factor causing their relative enrichment in the fly ash and rarely in the bottom ash and slag. 65 refs., 1 fig., 11 tabs

48

Ionizing collectors and their potential for floating high ash coals  

Energy Technology Data Exchange (ETDEWEB)

Flotation plant feed consisting of fine (-0.5 mm), high ash (35.1%) coal and flocculation feed containing very high ash (67.1%) were subjected to froth flotation tests with conventional and ionizing collectors. Methyl isobutyl carbinol (MIBC) and kerosene were used as conventional collectors, whereas Pamak4 (linoleic + oleic + Rosin oil) was selected as an ionizing collector in consideration of higher HLB (hydrophile-lipophile balance) value due to the oleic acid. The flotation results at the minimum reagent dosage levels for 35.1% ash coal revealed that Pamak4 was more effective than kerosene and MIBC combination, giving 20% higher yield of clean coal at the same ash level (i.e. 15%). At higher dosages Pamak4 continued this trend yield-wise, loosing the comparative benefit ash-wise due to the collector adsorption of clay coated coal particles. The flotation of 67.1% ash coal at the lowest collector dosage with Pamak4 gave 15.4% more yield of clean coal with 4% lower ash than that using kerogen and MIBC combination. It can be concluded from this study that both yield and ash content of clean coal account for the efficiency of flotation process and hence ionizing collectors such as Pamak4, due to their better activity than kerosene, have immense potential for floating fine high ash coals in future. 10 refs., 4 figs., 2 tabs.

Hussain, S.A.; Ozbayoglu, G. [University of Engineering and Technology, Lahore (Pakistan). Mining Engineering Dept.

1994-12-31

49

The determination of 210Pb in coal, coal ash, coal cinder and soil  

International Nuclear Information System (INIS)

A radiochemical method is described for the determination of 210Pb in coal, coal ash, coal cinder and soil. The procedure includes sample dry ashing, leaching with HCl (1+1), separation with anion-exchange resin, purification as PbS precipitate and 210Bi beta counting. This method provides a good separation of 210Pb from other natural and artificial beta emitters. The half-life of 210Bi determined from the sample sources is 5.50d, which is close to the published value (5.01d). The lower limits of detection are 7.6 x 10-4 Bq/g for 10 g coal sample and 1.5 x 10-3 Bq/g for each and every 5 g of coal ash, coal cinder and soil samples. The 210Pb contents in the analyzed coal, coal ash, coal cinder and soil samples are 0.0316 +- 0.0097, 0.0712 +- 0.0760, 0.0109 +- 0.0035 and 0.0355 +- 0.0173 Bq/g and the chemical yields are 95.1% +- 2.5%, 97.2% +- 2.0%, 93.5% +- 1.6% and 95.7% +- 1.5% respectively. The enrichment factors (Ef) of 210Pb in coal ash, defined as the ratio of the content of 210Pb in coal ash to that in coal, range from 1.60 to 11.8 the method gives precision results. Four samples can be analyzed within 12 h (not including the time for counting). The technique is suitable for sample analysis on the environmental impact assessment of the coal-fuel power plant

50

Mullitization of black coal fly ashes  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper are presented the results of experiments focused on the study of thermal treatment influence of selected black coal flyashes from the heating plant in Kosice and the power plant in Vojany. The study was realized with original not pretreated samples.The obtained results confirmed that after the thermal treatment of both samples the phase’s change of material occurred. At 1050 °C,the decrease of amorphous phase was remarked, being transformed to the mullite and spinel. This information allow of the use examinedfly ashes samples as the matrix for the mullite composites preparation providing the stoichiometric change of thermally treated mixture.

Mária Kušnierová

2011-12-01

51

Studies about bituminous coal ashes recover  

Energy Technology Data Exchange (ETDEWEB)

For the practical utilization of the ashes resulting from the burning of Jiu Valley bituminous coal, a large number of studies had to be undertaken, in order to develop a technology for their full use. Among the conclusions drawn from these studies, the possibility of recovering certain noble metals from magnetic concentrates is mentioned. Out of the tested procedures, the best proved to be chlorinating leaching where the best metal extraction and the lowest specific consumption of reagents were obtained. The corroding effects of the chlorinating reaction had to be taken into account when optimizing the process. 2 refs., 3 figs., 1 tab.

Plasea, V.; Traista, E.; Madear, G. [ICITPMH Petrosani, Petrosani (Romania)

1999-07-01

52

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

53

Effect of chemical composition of coal ash on readings of radioisotope ash meters  

International Nuclear Information System (INIS)

About 150 radioisotope ash meters, the readings of which are mostly used for operational control of processing operations, have been introduced at coal mining and coal processing facilities of the USSR. In addition to the significant advantages of these instruments (contactless instruments, speed, good representativeness of control), operation has also detected a number of series shortcomings, the principal one of which can be considered the effect of changes in ash composition on the measurement results. Since operation of nearly all radioisotope ash meters is based on the connection between effective atomic number of coal Z and its ash content, the distribution of light aluminosilicates and heavy ash-forming compounds of calcium and iron in the ash leads to changes of Z that are not correlated with ash content and, as a result, a significant error in control. Analysis of the effect of chemical composition of the coal ash on the readings of radioisotope ash meters was carried out on the basis of data from introduction and operation at the concentration plant of the Neryungrinsk Open-Pit Mine of the Yakutskugol Production Association of instruments to control coal ash content on line (RKTP-2) using the intensity of backscattered low-energy (60 keV) radiation as a function of ash content of the coal. The method of preliminary analysis of data on ash composition of coal proposed by the authors provides for evaluating the nonuniformity of the obtained data set, determination of the minimal admissible number of calibrations from the standpoint of measurement error and finally establishment of the optimal sensitivity to ash content corresponding to these calibration

54

Geotechnical properties of coal-fired thermal power plant ash  

Energy Technology Data Exchange (ETDEWEB)

This paper highlights that fly ash generated by coal-fired power plants has beneficial geotechnical properties, which could be utilized as a filling material for its adequate disposal. In this paper a typical composition of fly ash and bottom ash generated in the US has been tabulated. ASTM has distinguished the Class F and C ashes based on the concentration of silica, alumina and iron oxide and also as per the percentage of CaO content. It has been observed that dry unit weight of fly ash increases as its specific gravity increases. The bottom ash has indicated greater value of friction angle than sand. 16 refs., 3 tabs.

Roy, S. [National Institute of Rock Mechanics, Kolar Gold Fields (India)

2005-07-01

55

Environment friendly utilization of coal ash as a filling material in underground coal mines  

Energy Technology Data Exchange (ETDEWEB)

This document presents research work into the utilization of coal ash. Several laboratory studies have shown that coal ash could be used as a filling material for underground coal mines. The drainage properties of coal ash are inferior to those of river sand, which is an ideal material for mine filling. Many filling problems have been detected using numerous physical models developed in the laboratory and it has been found that ash fill drainage characteristics could be enhanced using a specific additive. To validate these laboratory findings, field trials have been conducted in a significant number of underground coal mines in India. This work has concluded that coal ash as a fill material has several advantages over river sand. In addition, this document also includes norms for the potential use of coal as a backfill material in underground coal mines.

Prashant, Mr; Ghosh, C.N.; Kumar, R.; Mandal, P.K. [Central Institute of Mining and Fuel Research (India)

2011-07-01

56

Adsorption of tungsten onto zeolite fly ash produced by hydrothermally treating fly ash in alkaline solution.  

Science.gov (United States)

Fly ash (FA) was hydrothermally treated in an alkaline solution to produce zeolite fly ash (Z-FA). The properties of the FA and Z-FA were investigated. The amounts of tungsten (W) adsorbed onto the FA and Z-FA surfaces were evaluated. Z-FA was produced by hydrothermally treating FA in an alkaline solution. The specific surface area and pore volume of the Z-FA were greater than those of the FA. More W was adsorbed onto the Z-FA surface than onto the FA surface. The adsorption isotherms for W were fitted using both the Freundlich and Langmuir equations. The equilibrium concentrations of W adsorbed onto the FA and Z-FA surfaces were subsequently reached within 20?h. The pseudo-second-order model more accurately described the data than did the pseudo-first-order model. Sodium hydroxide solutions (1-50?mmol/L) were used to easily recover W from Z-FA, indicating that Z-FA was useful for recovering W from aqueous solutions. PMID:25177018

Ogata, Fumihiko; Iwata, Yuka; Kawasaki, Naohito

2014-01-01

57

Fine ash formation during combustion of pulverised coal - coal property impacts  

Energy Technology Data Exchange (ETDEWEB)

In many countries, legislation has been enacted to set guidelines for ambient concentrations and to limit the emission of fine particulates with an aerodynamic diameter less than 10 {mu}m (PM10) and less than 2.5 {mu}m (PM2.5). Ash particles are formed during the combustion of coal in pf boilers and fine ash particulates may potentially pass collection devices. The ash size fractions of legislative interest formed during coal combustion are the result of several ash formation mechanisms; however, the contribution of each of the mechanisms to the fine ash remains unclear. This study provides insight into the mechanisms and coal characteristics responsible for the formation of fine ash. Five well characterized Australian bituminous coals have been burned in a laminar flow drop tube furnace in two oxygen environments to determine the amount and composition of the fine ash (PM10, PM2.5 and PM1) formed. Coal characteristics have been identified that correlate with the formation of fine ash during coal combustion. The results indicate that coal selection based on (1) char characterization and (2) ash fusion temperature could play an important role in the minimization of the fine ash formed. The implications of these findings for coal selection for use in pf-fired boilers are discussed. 35 refs., 6 figs., 7 tabs.

B.J.P. Buhre; J.T. Hinkley; R.P. Gupta; P.F. Nelson; T.F. Wall [University of Newcastle, Callaghan, NSW (Australia). Cooperative Research Centre for Coal in Sustainable Development, Department of Chemical Engineering

2006-01-01

58

Natural radioactivity level in coal and ash collected from Baoji coal-fired power plant  

International Nuclear Information System (INIS)

Specific activities of natural radionuclides 226Ra, 232Th and 40K were assessed in coal (3 samples), fly ash (17 samples) and bottom ash (6 samples) collected from Baoji coal-fired power plant. This paper analyzed the characteristics of 226Ra, 232Th and 40K contents in bottom ash and fly ash, and studied the concentration factors of these radionuclides in ash in relation to those in coal. The level of natural radionuclides 226Ra, 232Th and 40K of coal collected from Baoji coal-fired power plant are in the range of radionuclides contents of Chinese coal. The natural radioactivity level of fly ash collected from Baoji coal-fired power plant is close to Beijing and Shanghai coal-fired power plants. The paper farther assessed the possibility of fly ash of Baoji coal-fired power plant used as building materials according to the state standard. The results show that there are 29% samples exceeding the state limit when fly ash used as building materials. So the usage of fly ash in building material should be controlled. (authors)

59

Utilisation of coal ash to improve acid soil  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The study on utilization of coal ash to improve acid soil was carried out in a greenhouse at the Land Development Regional Office 1, Pathum Thani Province, Central Thailand, from January-May 2003. Fly ash mixture (fly ash plus gypsum and lime at the proportion 5:4:1) and clinker ash mixture (clinker ash plus gypsum and lime at the proportion 5:4:1) were used as soil amendments at varying rates i.e., 0, 6.25,12.5, 18.75 and 25 t/ha to improve the soil. The aim of this study was to determine th...

Shigeru Kato; Koji Kawashima; Tomoyuki Amano; Noparat Bamroongrugsa; Rungsun Im-Erb

2004-01-01

60

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

 
 
 
 
61

Ultrafine ash aerosols from coal combustion: Characterization and health effects  

Energy Technology Data Exchange (ETDEWEB)

Ultrafine coal fly-ash particles withdiameters less than 0.5 {mu}m typically comprise less than 1% of the total fly-ash mass. This paper reports research focused on both characterization and health effects of primary ultrafine coal ash aerosols alone. Ultrafine, fine, and coarse ash particles were segregated and collected from a coal burned in a 20 kW laboratory combustor and two additional coals burned in an externally heated drop tube furnace. Extracted samples from both combustors were characterized by transmission electron microscopy (TEM), wavelength dispersive X-ray fluorescence(WD-XRF) spectroscopy, Moessbauer spectroscopy, and X-ray absorption fine structure (XAFS) spectroscopy. Pulmonary inflammation was characterized by albumin concentrations in mouse lung lavage fluid after instillation of collected particles in saline solutions and a single direct inhalation exposure. Results indicate that coal ultrafine ash sometimes contains significant amounts of carbon, probably soot originating from coal tar volatiles, depending on coal type and combustion device. Surprisingly, XAFS results revealed the presence of chromium and thiophenic sulfur in the ultrafine ash particles. The instillation results suggested potential lung injury, the severity of which could be correlated with the carbon (soot) content of the ultrafines. This increased toxicity is consistent with theories in which the presence of carbon mediates transition metal (i.e., Fe) complexes, as revealed in this work by TEM and XAFS spectroscopy, promoting reactive oxygenspecies, oxidation-reduction cycling, and oxidative stress. 24 refs., 7 figs.

William P. Linak; Jong-Ik Yoo; Shirley J. Wasson; Weiyan Zhu; Jost O.L. Wendt; Frank E. Huggins; Yuanzhi Chen; Naresh Shah; Gerald P. Huffman; M. Ian Gilmour [US Environmental Protection Agency, Research Triangle Park, NC (United States). National Risk Management Research Laboratory

2007-07-01

62

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)

63

Identification and Quantification of Radionuclides in Coal Ash  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 residuals. Radiation emission is, in fact, a natural phenomenon for most materials, both natural and man-made, but in the case of coal ash residuals the process of combustion produces an inevitable concentration of radionuclides from the origi...

Alleman, James E.; Clikeman, Franklyn M.; Skronski, Thomas

1998-01-01

64

Prediction of coke CSR from ash chemistry of coal blend  

Energy Technology Data Exchange (ETDEWEB)

Coke reactivity index (CRI) and coke strength after reaction (CSR) are the most important parameters used to assess the blast-furnace coke quality. The present work describes the possibility of estimating CSR for coke from ash chemistry of coal blends. For development and validation of the regression model, data obtained from the Tata Steel's coke oven battery numbers 8 and 9 were utilized. It was found that CSR is greatly influenced by coal ash chemistry.

Nag, D.; Haldar, S.K.; Choudhary, P.K.; Banerjee, P.K. [Tata Steel, Jamshedpur (India). R& amp; D Division

2009-07-01

65

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

66

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

67

? ray on-line ash monitor for coal  

International Nuclear Information System (INIS)

For instrumented and automated coal dressing and briquetting processes to be operated under the optimum conditions, it is necessary to continuously measure the content of inconbustibles in coal (ash content) and to feed back the data to each process control system. To this end, the authors developed an on-line coal ash monitor of a two-radiation-source transmission type using the radioactive isotopes of 241Am and 137Cs. The structure and functions of the automatic ash content analyzing system is outlined in this report. The ash content A can be calculated from the measurement P, the ratio of the mass absorption coefficients of coal for 241Am and 137Cs, regardless of the thickness of the coal layer on the basis of the linear relationship between A and M. The ash content monitoring system consists of three sections, i.e., for source-detector, measurement and data processing. The signals from the detectors are sent to the counting unit in the measurement section after being amplified. The counting data are then fed to the processing unit, where the ash content is calculated. The counting data and the calculated ash content are shown in the display unit of the computer and the indicator of the measuring apparatus, outputted by the printer and indicated in analog meters. (Nogami, K.)

68

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

69

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

70

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

71

Utilization of Coal Fly Ash as CO Gas Adsorbent  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This research focused on coal fly ash fabricated as CO adsorbent. Coal fly ash having grain size of 325 mesh was characterized by XRF, XRD and SEM-EDX. Physical activation was done at temperatures of 5000C, 5200C, 5400C, 5600C, 5800C and 6000C. Chemical activation was undertaken by mixing between fly ash and NaOH with mass ratio of 1: 1.2 with subsequent heating at 7500C for 1 h and followed by w...

Ayu Lasryza; Dyah Sawitri

2012-01-01

72

Specification of the fineness of coal ash  

Energy Technology Data Exchange (ETDEWEB)

Specifications for the size distribution of coal ash usually consider one size, for example the mass retained on a 45{mu}m sieve, and ignore the general particle distribution. This over-simplified approach had tended to persist because alternative parameters, such as specific surface obtained from air permeability tests as used for cements, have been found to be even more unsatisfactory. However, if the size distribution is determined satisfactorily using modern techniques then it can be shown that a suitable parameter for the size distribution can be a valuable aid in characterising the material. The paper reviews the reasons for the deficiencies in the earlier tests for determining the fineness of PFA and then describes a technique for specifying PFA fineness which overcomes the problems associated with the above. The application of a suitable grading parameter for PFA is illustrated by reference to mix design for PFA concrete. Only by reference to the relevant characteristics of all the constituents of the concrete is it possible to design for a required property in the resulting concrete with any reasonable accuracy. A comprehensive method of mix design capable of accommodating different cements and PFAs as well as different fine and coarse aggregates and entrained air contents is outlined and it is seen that similar grading parameters can also be utilised for the aggregates to facilitate proportioning of constituents to achieve a required concrete workability in terms of Vebe time. 12 refs., 4 figs., 5 tabs.

Hughes, B.P. [University of Birmingham, Birmingham (United Kingdom). Dept. of Civil Engineering

1994-12-31

73

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

74

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

75

Coal and ash handling in a typical industrial boiler plant  

Energy Technology Data Exchange (ETDEWEB)

For the person considering coal as the primary fuel for a new plant, the systems that are unique to coal firing are of particular interest. This paper discussed two of those systems, namely coal handling and ash handling, for a typical, medium size, industrial boiler plant located in this general area. For the purposes of this paper, the typical boiler plant being considered will consist of three boilers each having a capacity of 80,000 lb/hr of steam. The peak load for the plant is assumed to be 160,000 lb/hr. The boilers are stoker fired and are provided with either electrostatic precipitators or baghouses. Based on the peak load of 160,000 lb/hr of steam, coal usage will be four tons per hour maximum per boiler, eight tons per hour total and perhaps 160 tons per day assuming some operation below peak. A plant this size will receive coal either by truck or by rail. The size, type and location of on-site coal storage must be considered initially when designing a coal handling system. Coal storage is either active from which the coal is fed directly to the boilers or reserve in which case the coal is held for future use. The purpose of reserve storage is to guard against interruptions of the coal supply due to strikes, weather or other causes. Reserve storage is usually outdoors, on the ground and uncovered. The amount to be stored should be a minimum of thirty days supply based on the peak month usage. Sixty days supply is quite common. A thirty day supply for this plant would be approximately 4000 tons and would cover an area of approximately 20,000 square feet assuming the coal is piled 10 feet high. A pneumatic system is usually selected for handling ashes and fly ash. Dust control may be repaired at transfer points in handling both coal and ashes.

Miller, R.J.

1981-01-01

76

Growth and elemental accumulation by canola on soil amended with coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

To explore the agronomic potential of an Australian coal fly ash, we conducted two glasshouse experiments in which we measured chlorophyll fluorescence, CO{sub 2} assimilation (A), transpiration, stomatal conductance, biomass accumulation, seed yield, and elemental uptake for canola (Brassica napus) grown on soil amended with an alkaline fly ash. In Experiment 1, application of up to 25 Mg/ha of fly ash increased A and plant weight early in the season before flowering and seed yield by up to 21%. However, at larger rates of ash application A, plant growth, chlorophyll concentration, and yield were all reduced. Increases in early vigor and seed yield were associated with enhanced uptake of phosphorus (P) by the plants treated with fly ash. Fly ash application did not influence accumulation of B, Cu, Mo, or Zn in the stems at any stage of plant growth or in the seed at harvest, except Mo concentration, which was elevated in the seed. Accumulation of these elements was mostly in the leaves, where concentrations of Cu and Mo increased with any amount of ash applied while that of B occurred only with ash applied at 625 Mg/ha. In Experiment 2, fly ash applied at 500 Mg/ha and mixed into the whole 30 cm soil core was detrimental to growth and yield of canola, compared with restricting mixing to 5 or 15 cm depth. In contrast, application of ash at 250 Mg/ha with increasing depth of mixing increased A and seed yield. We concluded that fly ash applied at not more than 25 Mg/ha and mixed into the top 10 to 15 cm of soil is sufficient to obtain yield benefits.

Yunusa, I.A.M.; Manoharan, V.; DeSilva, D.L.; Eamus, D.; Murray, B.R.; Nissanka, S.P. [University of Technology Sydney, Sydney, NSW (Australia)

2008-05-15

77

Growth and elemental accumulation by canola on soil amended with coal fly ash.  

Science.gov (United States)

To explore the agronomic potential of an Australian coal fly ash, we conducted two glasshouse experiments in which we measured chlorophyll fluorescence, CO2 assimilation (A), transpiration, stomatal conductance, biomass accumulation, seed yield, and elemental uptake for canola (Brassica napus) grown on soil amended with an alkaline fly ash. In Experiment 1, application of up to 25 Mg/ha of fly ash increased A and plant weight early in the season before flowering and seed yield by up to 21%. However, at larger rates of ash application A, plant growth, chlorophyll concentration, and yield were all reduced. Increases in early vigor and seed yield were associated with enhanced uptake of phosphorus (P) by the plants treated with fly ash. Fly ash application did not influence accumulation of B, Cu, Mo, or Zn in the stems at any stage of plant growth or in the seed at harvest, except Mo concentration, which was elevated in the seed. Accumulation of these elements was mostly in the leaves, where concentrations of Cu and Mo increased with any amount of ash applied while that of B occurred only with ash applied at 625 Mg/ha. In Experiment 2, fly ash applied at 500 Mg/ha and mixed into the whole 30 cm soil core was detrimental to growth and yield of canola, compared with restricting mixing to 5 or 15 cm depth. In contrast, application of ash at 250 Mg/ha with increasing depth of mixing increased A and seed yield. We concluded that fly ash applied at not more than 25 Mg/ha and mixed into the top 10 to 15 cm of soil is sufficient to obtain yield benefits. PMID:18453446

Yunusa, I A M; Manoharan, V; DeSilva, D L; Eamus, D; Murray, B R; Nissanka, S P

2008-01-01

78

Utilisation of coal ash to improve acid soil  

Directory of Open Access Journals (Sweden)

Full Text Available The study on utilization of coal ash to improve acid soil was carried out in a greenhouse at the Land Development Regional Office 1, Pathum Thani Province, Central Thailand, from January-May 2003. Fly ash mixture (fly ash plus gypsum and lime at the proportion 5:4:1 and clinker ash mixture (clinker ash plus gypsum and lime at the proportion 5:4:1 were used as soil amendments at varying rates i.e., 0, 6.25,12.5, 18.75 and 25 t/ha to improve the soil. The aim of this study was to determine the effect of application of coal ash on acid soil and the growth of a vegetable (Chinese kale. Chinese kale cultivars were planted in a randomized complete block design with three replications. Pak Chong soil series (Ultisols was used as the growth medium. Twenty-day-old seedlings were transplanted in 270 pots (two plants per pot containing acid soil with different treatments of coal ash mixture which were as follows: 1 control, 2 fly ash mixture 6.25 t/ha, 3 fly ash mixture 12.5 t/ha, 4 fly ash mixture 18.75 t/ha, 5 fly ash mixture 25 t/ha, 6 clinker ash mixture 6.25 t/ha, 7 clinker ash mixture 12.5 t/ha, 8 clinker ash mixture 18.75 t/ha and 9 clinker ash mixture 25 t/ha. Chemical fertilizers were applied at the rate of 250 kg/ha using a grade of 15-15-15 of N, P and K, respectively. Plants were harvested 40 days after transplanting. Among the treatments, application of fly ashmixture at a rate of 25t/ha (4t/rai substantially increased soil pH up to 5.7. Fly ash was found more effective than clinker ash in increasing soil pH. The highest yield of Chinese kale was also obtained when fly ash mixture was applied at a rate of 25 t/ha followed by fly ash mixture at 18.75 t/ha and clinker ash mixture at 18.75 t/ha with an average yield per plant of 4.980, 3.743 and 3.447 grams, respectively. It can be concluded that the application of coal ash mixture, either fly- or clinker ash, at 18.75-25 t/ha (3-4 t/rai was the most effective in terms of plant yield. The use of coal ash mixture increased cation exchange capacity, base saturationpercentage and Ca, Mg and S contents in the soil as well as plant uptake of N. The concentrations of heavy metals in the soil (Cd, As, Co, Cr, Cu, Hg, Ni, Pb and Zn were found to be within permissible levels while Cd, Cr and Ni in the plants were at critical levels for health.

Shigeru Kato

2004-09-01

79

Mechanism of bioleaching of coal fly ash by Thiobacillus thiooxidans  

Energy Technology Data Exchange (ETDEWEB)

Bioleaching of aluminum and iron from coal fly ash (CFA) by Thiobacillus thiooxidans (T thiooxidans) bacteria is considered. The interactions between bacteria, metabolic products, CFA particles, and leaching products were studied. It is demonstrated that bacterial growth and the amount of metals leached from the CFA are coupled through biological and chemical interactions, which involve the various components in this system. Bioleaching experiments were performed batch wise by suspending up to 10% (w/v) CFA in T thiooxidans growth medium containing cell inoculum for a typical 3 week period of time. The results show that under the same conditions, similar leaching levels are obtained by sulfuric acid and bioleaching of CFA, and the contribution of other metabolites is insignificant. CFA inhibits the growth rate through two major effects. The first is due to the alkaline components released by the CFA that cause a rise in the pH, and a corresponding delay in growth. The second is attributed to the random attachment of the bacteria to both the sulfur particles (the energy source) and the barren CFA particles, resulting in a so-called 'dilution effect' of the sulfur particles, and an inhibition of the initial growth rate. However, after an adaptation period of the bacteria the subsequent growth rate, the maximal cell concentration and minimal pH were similar to those obtained in the control experiment, irrespective of CFA content.

Seidel, A.; Zimmels, Y.; Armon, R. [Technion Israel Institute of Technology, Haifa (Israel). Faculty of Civil Engineering

2001-06-15

80

Chemical speciation of vanadium in coal bottom Ash  

Energy Technology Data Exchange (ETDEWEB)

Chemical speciation of vanadium is important to understand the true nature of this element in the environment as well as its biochemical pathways. Sample pretreatment, preparation, and chemical speciation methods were applied for vanadium in coal bottom ash here. Two-stage microwave acid digestion was used to preparation of samples. Determination of vanadium was performed using inductively coupled plasma-optical emission spectrometry (ICP-OES). Speciation of vanadium was carried out using a seven-step sequential extraction procedure of the coal bottom ash each releasing species of vanadium: Water soluble, exchangeable, carbonate, reducible, oxidizable, sulfide, and residual fractions. Total vanadium concentration in the coal bottom ash is 701 mg kg{sup -1} d.w. The most abundant form of vanadium in coal bottom ash is residual fraction of vanadium (196 mg kg{sup -1} d.w.). Relative abundances of the remaining vanadium fractions in coal bottom ash are as follows: Reducible (176 mg kg{sup -1} d.w.) > sulfide (176 mg kg{sup -1} d.w.) > carbonate (85 mg kg{sup -1} d.w.) > oxidizable (50 mg kg{sup -1} d.w.) > water soluble (10.6 mg kg{sup -1} d.w.) > exchangeable (9.0 mg kg{sup -1} d.w.). (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Aydin, Firat; Aydin, Isil; Hamamci, Candan [Science Faculty, Chemistry Department, Dicle University, Diyarbakir (Turkey); Saydut, Abdurrahman [Engineering Faculty, Mining Engineering Department, Dicle University, Diyarbakir (Turkey); Gunduz, Beniz [Science Faculty, Chemistry Department, Selcuk University, Konya (Turkey)

2012-04-15

 
 
 
 
81

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 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

82

Use of lagoon stored coal fly ash in gravel-cement-fly ash road  

Energy Technology Data Exchange (ETDEWEB)

The 10,000 MN of coal ash produced at the Andorra coal-fired power plant is dumped into the Valdeserrana lagoon bound by a dam. The waste is mixed with water and goes through one pipe. Its pumping location varies while the lagoon is being filled. The waste is comprised of a mixture of 15 per cent bottom ash and 85 per cent fly ash. The objective of this study was to determine the feasibility of using fly ash from the lagoon for use in road base and gravel-cement bases. Another objective was to establish mixture proportions needed to obtain the appropriate material for road bases according to Spanish and European standards and regulations. The final objective was to establish execution methods suitable for the material characteristics. The chemical composition of the ash in the lagoon is similar to that of dry ash, but mineralogical analysis indicate there is a decrease of the vitreous components that would account for a decrease of its pozzolanic properties. Various proportions of these ashes were mixed with cement and gravel and their mechanical properties were laboratory tested. Results demonstrate a certain heterogeneity in the behaviour of the mixtures, depending on the fly ash storage age. It was noted that the addition of fly ash improved the compressive strength of the gravel-cement-fly ash road based, but only up to a certain point. After that point, the strength decreased. The increase in strength was most significant after 90 days. The resistance to erosion also improved with increasing proportions of fly ash, but the best resistance to erosion was found in the control sample which did not have any fly ash in it. 17 refs., 3 tabs., 6 figs.

Calderon, P.A.; Peris, E. [Univ. Politecnica de Valencia (Spain). Dept. of Engineering Construction; Parrilla, J. [Arquitectos-Ingenieros Consultores, S.L., Valencia (Spain)

2001-07-01

83

Desulphurization of low ash and high sulphur coal from Assam  

Energy Technology Data Exchange (ETDEWEB)

Attempts made to reduce the sulphur from a low ash and high sulphur coal sample from Assam by froth flotation followed by bacterial leaching of the flotation concentrate are highlighted and discussed in this article. The paper states that attempts made to float the coal using light diesel oil to depress pyrite have met with little success. Around 15% of the total sulphur could be removed from a coal sample of Assam by flotation followed by bacterial leaching using Pseudomonas aureofaciens. However, Thiobacillus was found ineffective in removing the sulphur from the flotation concentrate of the coal. It is presumed that the diesel oil, which was used as collector during flotation of this high sulphur coal, must have acted as barrier for this bacterial action. Earlier, Thiobacillus ferrooxidans had removed around 30% pyrite from Assam coals. Also a mixed culture of Thiobacillus removed around 38.23% of the total sulphur from chemically pretreated Assam coal. 9 refs.

Acharya, C.; Rao, G.V.; Kar, R.N.; Sukla, L.B. [Regional Research Laboratory, Bhubaneswar (India)

1999-03-01

84

Occurrence and mobilization potential of trace elements from disposed coal combustion fly ash  

Energy Technology Data Exchange (ETDEWEB)

Although there is a large market for coal combustion waste (CCW), most of this waste product, particularly fly ash (FA), is disposed of annually in surface ponds or landfills. The total stored amount also continues to grow. When fly ash is exposed to atmospheric conditions it can pose a threat to the environment. This paper presented a case study of time-delayed post-closure transformations of pore solution quality in the Przezchlebie disposal site in Poland. FA from the Rybnik power plant was hydraulically disposed in a surface pond from 1979 to 1991 in an abandoned quarry. The fly ash is an alkaline aluminum silicate material. In the post-closure period, dewatering of the pond occurred, along with a transformation of the hydrogeologic conditions within the FA layer. This anthropogenic zone was sampled along vertical profiles. Pore solution from fly ash samples was extracted by the pressure method under nitrogen and analyzed for the metal content. The chemical composition of pore solutions reflects the altered water flow and the changed equilibria conditions. The pore solution in the loose fly ash profiles indicates alteration of buffering properties of the system. Reactions between kaolinite and gibbsite at the stage of their formation were suggested. This resulted in a high non-linear release of trace elements from fly ash and major qualitative and quantitative increases of pollution potential for groundwater and soils in adjacent areas. 2 refs., 1 tab.

Twardowska, I. [Polish Academy of Science, Inst. of Environmental Engineering, Zabrze (Poland); Szczepanska, J. [University of Mining and Metallurgy, Krakow (Poland). Dept. of Hydrogeology and Water Protection

2001-07-01

85

On-conveyor belt determination of ash in coal  

International Nuclear Information System (INIS)

A laboratory feasibility study has been carried out on new and advanced neutron and gamma-ray analysis systems for the direct on-conveyor belt analysis of ash in coal without the need for sample by-lines. Such an analysis system could deliver the combined advantages of a direct on-conveyor configuration with new and accurate analysis techniques. An industry survey of 18 coal companies carried out in early 1996 indicated that accurate on-belt ash analysis is of the highest priority. Subsequent laboratory work has focussed on the investigation of methods with the potential for improving the accuracy of ash content measurement relative to existing on-belt ash analysers, the most widely-used of which are based on dual energy gamma-ray transmission (DUET), which is sensitive to variations in ash composition. The current work indicates that on-belt neutron/gamma-ray techniques combined with advanced spectral analysis techniques show promise for development into an on-belt ash analysis system which is significantly less sensitive to composition changes than DUET and which analyses a much larger proportion of coal on the belt, thus eliminating some key sources of analysis error

86

Radioisotope instrument for monitoring ash content of coal concentration products  

International Nuclear Information System (INIS)

The PRZ-7605 radioisotope instrument for monitoring the ash content of coal concentration products was developed for operational monitoring of fuel ash content. The ash meter is intended for continuous and contactless measurement of ash content on a conveyor belt in the range from 5 to 35%; at an ash content of less than 10% the absolute error is ±0.8%, at an ash content of 10-35% - no more than ±0.08%. The instrument has two measurement subranges: from 5 to 20 and from 20 to 35% and carries out periodic control of the stability of the ash content readings on a built-in reference sample. The size of the fuel pieces should not exceed 100 mm. The minimal admissible thickness of the bed of material on the conveyor is ? 100 mm. The duration of one measurement cycle is 2 seconds with integration of the output value for fuel ash content from 1 to 10 minutes with a discreteness of 1 minute. The measurement results in the form of a continuous dc electric signal in the range from 0 to 5 or from 4 to 20 mA, and also in the form of a 16-digit binary-decimal code can be sent to a control computer or to secondary recording instruments. The information concerning ash content is output to a four-digit decimal display

87

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

88

Synthesis of high ion exchange zeolites from coal fly ash  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study focuses on the synthesis at a pilot plant scale of zeolitic material obtained from the coal fly ashes of the Teruel and Narcea power plants in Spain. After the optimisation of the synthesis parameters at laboratory scale, the Teruel and Narcea fly ashes were selected as low and high glass fly ashes. The pilot plant scale experiments were carried out in a 10 m3 reactor of Clariant SA (Barcelona, Spain). The results allowed obtaining 1.1 and 2.2 tonnes of zeolitic material with 40 an...

Ayora, Carlos; Querol, Xavier; Moreno, N.; Alastuey, Andre?s; Juan Mainar, Roberto; Andre?s Gimeno, Jose? Manuel; Lo?pez Soler, A?ngel; Medinaceli, Alejandro; Valero, Antonio

2007-01-01

89

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

90

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 unstable phases into more stable forms, takes, at best, hundreds or even hundreds of thousands of years.

91

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

92

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

93

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.)

94

Long-term evaluation of coal fly ash and mine tailings co-placement: a site-specific study.  

Science.gov (United States)

This study presents the results of a laboratory investigation conducted to evaluate the efficiency of coal fly ash to control the formation of acid mine drainage (AMD) from mine waste. Site-specific materials, coal fly ash from Atikokan Thermal Generating Station and mine tailings from Musselwhite mine, were mixed at different proportions for the investigation of the drainage chemistry and the optimal mix using static testing (acid-base accounting) and kinetic (column) testing. The acid-base accounting (ABA) results indicated that the fly ash possessed strong alkaline (neutralization) potential (NP) and could be used in the management of reactive mine tailings, thus ensuring prevention of AMD in the long-term. Column tests conducted in the laboratory to further investigate long-term performance of fly ash in the neutralization and prevention of acid mine drainage from tailings similarly showed that mixing fly ash with mine tailings reduces dissolution of many heavy metals from tailings by providing alkalinity to the system. It was found that a fly ash to tailings mass ratio equal to or greater than 15% can effectively prevent AMD generation from Musselwhite mine tailings in the co-placement approach. PMID:19744768

Yeheyis, Muluken B; Shang, Julie Q; Yanful, Ernest K

2009-10-01

95

Radioisotopic express analysis of ash components in coal  

International Nuclear Information System (INIS)

A method of radioisotopic analysis of coal ash, permitting measurement with high accuracy (accuracy at the level of chemical analysis), has been developed. The method is based on simultaneous registration of the back scattered and penetrating gamma irradiation from the investigated medium

96

Conversion of different ash content brown coal in fluidized bed  

Energy Technology Data Exchange (ETDEWEB)

Available equations used to determine combustion specific rate of coal-derived cokes describe the burning of carbon particles well enough but are not accurate in case of ash-containing coke particles combustion. This study is an attempt to account for the influence of both initial ash content and its increase in the course of carbon conversion in specific rate calculations. The results of experimental study of burn-out dynamics of Volchanskiy field (North Urals) brown coal and its coke with different ash content under conditions of fluidized bed combustion at impulse-type non-gradient reactor RSC-1 and dynamic installation Pyrolysis-M are summarized. Diffusion and heterogeneous (kinetic) components of carbon combustion rate are identified separately by using diffusion and kinetics equation with correction for carbon mass fraction in particles. Burning particle overheating values and heterogeneous combustion rate constants at different temperatures are estimated.

Osipov, P.; Chernyavskiy, N.; Ryzhkov, A.; Remenuk, A. [Ural Federal Univ., Ekaterinburg (Russian Federation). Dept. of Thermal Power Plants; Dulienko, S. [National Academy of Science of Ukraine, Kiev (Ukraine). Coal Energy Technology Inst.

2013-07-01

97

Radiometric determination of ash content in brown coal  

International Nuclear Information System (INIS)

The possibilities of ash content determination in brown coal from the ''Turow'' strip mine, using a portable radioisotope X-ray fluorescence analyser have been investigated. Negative results were obtained when the characteristic radiation of iron was measured. Therefore, in further investigations the scattering of X-rays from 238Pu-source was applied. In this case a vanadium filter was used to eliminate fluorescent radiation of iron. The measurements were carried out on 30 coal samples of variable moisture, containing 13-45 per cent of ash. The experiments have shown that, with measurement times of about 1 min. the absolute standard error of ash content determination is about 2 per cent. (author)

98

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

99

Production of ceramics from coal fly ash  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

100

Utilization of Atikokan coal fly ash in acid rock drainage control from Musselwhite Mine tailings  

International Nuclear Information System (INIS)

Acid rock drainage (ARD) is the greatest environmental liability facing the mining industry. Mines produce acidic effluents that are generated from the chemical reaction of sulphide containing minerals and atmospheric oxygen. The effluents have a pH value as low as 2 to 4 and their movement is accompanied by heavy metals which damage the ecosystem. This paper described some of the ARD-preventing technologies that are under investigation. In particular, it examined the feasibility of using Atikokan coal fly ash (AFA) as a buffering material to control and mitigate the generation of ARD from reactive Musselwhite Mine gold mine tailings. Coal fly ash is the residue resulting from the combustion of coal at electric generating plants. It consists of organic and inorganic matter, including silica, alumina, iron and calcium oxide with various amounts of carbon. More than 40,000 tons of fly ash is generated each year from the Atikokan Generating Station located 190 km west of the mine, of which 80 per cent is used for concrete manufacturing. In this study, experiments were conducted to determine the physical, chemical and mineralogical properties of both the fly ash residue and mine tailings. Six kinetic column permeation tests were then performed to monitor the leaching properties of the fly ash and the coal fly ash-mine tailings mixtures to determine the hydraulic conductivities resulting from pozzolanic reactions. The potential impacts of the disposal of AFA and mine tailings were also assessed. The study showed that the hydraulic conductivities of high-calcium AFA and the ash-tailings mixtures were greatly reduced upon contact with ARD. The pH of the pore fluid increased from acidic to alkaline. The concentration of regulated elements in the leachate from the ash-tailings mixtures were also below the limits set by the Ontario Ministry of Environment. The results indicate that AFA could mitigate the generation of ARD from reactive Musselwhite Mine gold mine tailings. 1 ref., 6 tabs., 10 figs., 1 appendix

 
 
 
 
101

The reaction of acid mine drainage with fly ash from coal combustion  

International Nuclear Information System (INIS)

The placement of alkaline fly ash in abandoned, reclaimed or active surface coal mines is intended to reduce the amount of acid mine drainage (AMD) produced at such sites by neutralization, inhibition of acid forming bacteria, encapsulation of the pyrite or water diversion. A continuing concern with this application is the potential release of trace elements from the fly ash when it is placed in contact with AMD. To investigate the possible release of antimony, arsenic, barium, boron, cadmium, chromium, cobalt, copper, lead, nickel, selenium, and zinc from fly ash, a series of column leaching tests were conducted. A one kg fly ash sample, placed in a 5-cm by 1 m acrylic columns, was leached at a nominal rate of 250 mL/d for between 30 and 60 days. The leachant solutions were deionized water, and dilute solutions of sulfuric acid and ferric chloride. Leaching tests have been completed on 28 fly ash samples. leachate data, analyzed as the mass extracted with respect to the concentration in the solid, indicate that the release of trace elements is variable, with only barium and zinc extracted at greater than 50 pct of the amount present in the original sample. As a comparison, water quality changes have been monitored at three sites where fly ash grout was injected after reclamation to control AMD. When compared before and after grouting, small increases in pH and decreases in acidity at discharge points were observed. Concentrations of trace metals were found to be compions of trace metals were found to be comparable in treated and untreated areas. When grouted and ungrouted areas were compared, the effect of the fly ash was shown to be localized in the areas of injection. These studies indicated that when fly ash is used as a reagent to control of AMD, the release of trace elements is relatively small

102

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

103

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

104

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)

105

Chemical, mineralogical and morphological changes in weathered coal fly ash: a case study of a brine impacted wet ash dump.  

Science.gov (United States)

The mobility of species in coal fly ash (FA), co-disposed with brine using a wet ash handling system, from a coal fired power generating utility has been investigated. The study was conducted in order to establish if the wet ash dump could act as a salt sink. The ash was dumped as a slurry with 5:1 brine/ash ratio and the dam was in operation for 20 years. Weathered FA samples were collected along three cores at a South African power station's wet ash dump by drilling and sampling the ash at 1.5 m depth intervals. A fresh FA sample was collected from the hoppers in the ash collection system at the power station. Characterization of both fresh FA and weathered FA obtained from the drilled cores S1, S2 and S3 was done using X-ray diffraction (XRD) for mineralogy, X-ray fluorescence (XRF) for chemical composition and scanning electron microscopy (SEM) for morphology. Analysis of extracted pore water and moisture content determination of the fresh FA and the weathered FA obtained from the drilled cores S1, S2 and S3 was done in order to evaluate the physico-chemical properties of the FA. The XRD analysis revealed changes in mineralogy along cores S1, S2 and S3 in comparison with the fresh FA. The SEM analysis revealed spherical particles with smooth outer surfaces for the fresh FA while the weathered ash samples obtained from cores S1, S2 and S3 consisted of agglomerated, irregular particles appearing to be encrusted, etched and corroded showing that weathering and leaching had occurred in the ash dump. The moisture content (MC) analysis carried out on the fresh FA (1.8%) and the weathered FA obtained from the drilled cores S1 (41.4-73.2%), S2 (30.3-94%) and S3 (21.7-76.2%)indicated that the ash dump was water logged hence creating favourable conditions for leaching of species. The fresh fly ash (n = 3) had a pH of 12.38 ± 0.15, EC value of 4.98 ± 0.03 mS/cm and TDS value of 2.68 ± 0.03 g/L, the pH of the drilled core S1 (n = 45) was 10.04 ± 0.50, the EC value was 1.08 ± 0.14 mS/cm and the TDS value was 0.64 ± 0.08 g/L. Core S2 (n = 105) had pH of 10.04 ± 0.23; EC was 1.08 ± 0.06 mS/cm and TDS was 0.64 ± 0.04 g/L, while core S3 (n = 66) had pH of 11.04 ± 0.09; EC was 0.99 ± 0.03 mS/cm and TDS was 0.57 ± 0.01 g/L. The changes in pH values can be attributed to the dissolution and flushing out of alkaline oxides like CaO and MgO from the dumped ash. The variations in pH values shows that the fly ash is acidifying over time and metal mobility can be expected under these conditions. The large decrease of EC in the drilled ash cores S1, S2 and S3 compared to the fresh ash indicated a major loss of ionic species over time in the ash dump. The XRF analysis showed the progressive dissolution of the major aluminosilicate ash matrix which influenced the release of minor and trace elements into the pore water enhancing their mobility as the ash dam acidified over time. Brine co-disposal on the ash may have been responsible for the slight enrichment of some species such as Na (0.27-0.56%), SO4(2-) (0.06-0.08%), Mg (0.57-0.96 %) and K (0.02-0.34%) in the disposed weathered FA. However, there was no significant accumulation of these species in the disposed FA despite continuous addition of large volumes of highly saline brine over the 20 year period that the dump existed, indicating that the ash dam was incapable of holding salts and continually released elements to the environment over the lifetime of the dam. PMID:24013557

Eze, Chuks P; Nyale, Sammy M; Akinyeye, Richard O; Gitari, Wilson M; Akinyemi, Segun A; Fatoba, Olanrewaju O; Petrik, Leslie F

2013-11-15

106

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

107

Radiometric determination of uranium leached biochemically from coal fly ashes  

International Nuclear Information System (INIS)

The method of radiometric determination of uranium leached by Thiobacillus ferrooxidans bacteria from fly ashes of hard and brown coals has been developed. The leached uranium was extracted from leaching medium by using toluene solution of tributylphosphate. To the organic phase containing extracted uranium the scintillation solution Permafluor 1 was added and solution activity was recorded using scintillation counter. The elaborated method enables to determine trace amounts of the leached uranium (?10-7 g/ml) in leaching solution containing bacterial culture Thiobacillus ferrooxidans and suspended ashes. (author)

108

Usage of Ash from Coal incineration in Wuhai, China  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

109

Sulfated formations when burning coals with an acid ash composition  

Energy Technology Data Exchange (ETDEWEB)

Results of studies on sulfated formations during the combustion of fuels with a high content of calcium compounds are discussed. The results of investigations on the kinetics of the sulfidization of fuel samples with an acidic ash composition are presented. It is concluded that during the combustion of coals with a caustic ash content, calcium-sulfate deposits are formed due to the caking properties of concentrated calcium oxide particles reacting with the heating surfaces. The deposits harden in time because of caking and sulfidization. 2 refs.

Alekhnovich, A.N.; Bogomolov, V.V.; Ivanova, N.I.; Gladkov, V.E.

1987-02-01

110

Understanding and mastering coal fired ashes geopolymerisation process in order to turn potential into profit (GEOASH)  

Energy Technology Data Exchange (ETDEWEB)

The EU regulations are restrictive with regard to solid residues and waste management. Research efforts to develop satisfying solutions are thus necessary. The GEOASH project aims, on one hand, at producing new geopolymeric matrixes using the advantageous properties of fine particles extracted from (co)-combustion fly ashes for the long-term stabilisation of inorganic hazardous wastes and, on the other, at predicting technologies for the recycling of coal ashes into added-value products which could be integrated in manufacture processes, allowing a reduction of primary resources consumption. The new geopolymer matrixes produced at room temperature in moderate alkaline conditions display a compressive strength of 60-80 MPa that is not affected by the particle size of the starting fly ashes. High content of unburned carbon (10 %) in the fly ash inhibits the reactions. The higher the amorphous phases content in fly ashes the higher the polymerisation degree typical of the geopolymer framework. Additionally, fly ashes with a high SiO{sub 2}/Al{sub 2}O{sub 3} ratio require less chemical reagents to reach high compressive strength, reducing significantly the cost of the geopolymerisation. Considering the pilot plant tests performed with a semi-industrial mixer, it appears that the amounts of water and chemical reagents may be reduced at pilot plant scale without an appreciable sacrifice in the properties of the geopolymer solids. Despite the rather satisfying results obtained by the leaching tests applied to two multimetal wastes that are difficult to stabilise, such as the MSWI residues and arc furnace dust solidified/stabilised in fly ash-based geopolymer matrixes, further research is still needed. 43 refs., 44 figs., 49 tabs.

Antenucci, D.; Philippart, C.; Lorenzi, G. (and others) [ISSeP, Liege (Belgium)

2009-07-01

111

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

112

BIOAVAILABILITY OF 1-NITROPYRENE FROM MODEL COAL FLY ASH AND ITS UPTAKE BY ALVEOLAR MACROPHAGES  

Science.gov (United States)

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...

113

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

114

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

115

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)

116

[Informative document fly ash of coal-fired power plants.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This "Informative document fly ash of coal-fired power plants" forms part of a series of "Informative documents waste materials". These documents are conducted by RIVM on the instructions of the Directorate General for the Environment, Waste Materials Directorate, in behalf of the program of action on "prevention and recycling of waste materials". In the documents a survey is given of the main facts and figures on specific waste materials...

Ih, Anthonissen; Kamphuis C

2012-01-01

117

Mosses accumulate heavy metals from the substrata of coal ash  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 meta...

Vukojevi? Vanja; Sabovljevi? Marko; Jovanovi? S.

2005-01-01

118

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

119

Soil stabilisation using alkaline activation of fly ash for self-compacting rammed earth construction  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper studies the effectiveness of alkaline activation of low-calcium fly ash on the improvement of residual granitic soils to be used on rammed-earth construction. Different liquid:solid ratios, alkali concentrations and Na2O : ash ratios were tested. Effect of calcium hidroxide, sodium chloride and concrete superplasticiser is also reported. Compressive strength up to 7 days at 60ºC was determined. Results show that, in terms of mechanical strength, there is an optimum value for the a...

Cristelo, Nuno; Glendinning, Stephanie; Miranda, Tiago F. S.; Oliveira, Daniel V.; Silva, Rui Andre? Martins Da

2012-01-01

120

On-line analyzer of ash content in coal  

International Nuclear Information System (INIS)

The radioisotope method for ash content measurement consists in effective atomic number (Z) determination. The considerable difference between Z of combustible and noncombustible coal phases is used. Due to changeable chemical composition and physical structure of the material, the radiations with two different energies are used and their attenuation and scattering is registered. In order to avoid the impact of the variable size and surface of the material on the transportation line, a wide-surface proportional detector is used. It registers the scattering of X-ray radiation (Pu-238 or Cd-109) from the coal surface of about 0.1 m2. The gamma radiation (Am-241) passing through the coal is registered by a scintillation probe. The developed ash-meter works with a bound torsion scales that continuously transmits signal of the instant load and the total material quantity. The measurement system is developed on the basis of a PC AT industrial type. All system elements, analytical software and the construction itself are Bulgarian made. The sensitivity, accuracy and measurement rate of the equipment are in no way inferior to the best foreign analogues and excel the ash-meters from former East Germany and Czechoslovakia. The analyzer is installed and at present is being tested in real production conditions at Maritza-East-2 Thermal Power Plant. (author)

 
 
 
 
121

On stream ash analysis of coal based on its natural gamma-ray activity  

International Nuclear Information System (INIS)

A novel method based on the natural gamma-ray activity of coal has been developed for the on-stream determination of ash. The accuracy of the method has been verified by measuring the natural gamma-ray activity and ash content of coal samples from a number of locations in New Zealand and Australia. The rms differences between % ash by ignition and % ash by the gamma-ray method ranged from 0.65% ash for coal samples from a Queensland mine to 1.6% ash for samples from a southern New South Wales mine. The rms errors include those to geovariance, and due to sampling and sample analysis by conventional means. The error in ash measurement by the gamma-ray method can therefore be reduced by substantially eliminating these errors. A prototype ash analyser was also developed and field-tested at the Huntly East mine. In a four-week test, the prototype gauge was used to determine the ash content of run-of-mine (rom) coal below 20% ash to within +- 1.7% ash. Laboratory studies of coal samples collected during the field test of the prototype gave an error of 0.8% ash for coal samples below 20% ash content. A higher error was observed in the field test compared with laboratory data, and the difference is attributed to errors in sampling from the conveyor belt

122

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

123

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

124

Novel materials based on microspheres from coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

Several morphological types of microspheres, comparable with synthetic ones by the composition and the properties, are generated during high-temperature thermochemical transformations while burning coal at the power plants. The three-step process for separation of ashes formed as a result of burning three different types of coals, including magnetic separation, hydrodynamic separation and granulometric classification, enabled us to obtain a wide range of stabilized products of magnetic microspheres and cenospheres with purity of 96-99% by the magnetic component. The physical and chemical properties as well as the morphology of the products obtained have been studied in detail by the methods of scanning electron microscopy (SEM), X-ray diffraction, Moessbauer and ESR spectroscopies. The general regularities of microsphere generation from a ferrosilicate melt in burning of coals of different types and the areas of application for the microspheres of different morphological types have been analyzed. The report describes the results of work in the following directions: Recovery of close-cut fractions of microspheres of stabilized composition from fly ashes of three power-generating coals of Russia. Morphological features of magnetic microspheres and cenospheres. Composition and physicochemical properties of close-cut fractions of microspheres of stabilized composition. Application areas of glass crystalline microspheres: catalysts of oxidative conversion of methane; microspherical porous glasses and sorbents on the basis of cenospheres; porous matrices for high-toxic waste disposal, in particular, for liquid radioactive waste. 15 refs., 6 figs., 1 tab.

A.G. Anshits; T.A. Vereshchagina; O.M. Sharonova; N.N. Anshits; E.V. Rabchevskii; O.A. Bayukov; S.V. Podoinitsyn [Institute of Chemistry and Chemical Technology (Russian Federation)

2003-07-01

125

Environmental impacts of the Tennessee Valley Authority Kingston coal ash spill. 2. Effect of coal ash on methylmercury in historically contaminated river sediments.  

Science.gov (United States)

The Tennessee Valley Authority Kingston coal ash spill in December 2008 deposited approximately 4.1 million m(3) of fly ash and bottom ash into the Emory and Clinch River system (Harriman, Tennessee, U.S.A.). The objective of this study was to investigate the impact of the ash on surface water and sediment quality over an eighteen month period after the spill, with a specific focus on mercury and methylmercury in sediments. Our results indicated that surface water quality was not impaired with respect to total mercury concentrations. However, in the sediments of the Emory River near the coal ash spill, total mercury concentrations were 3- to 4-times greater than sediments several miles upstream of the ash spill. Similarly, methylmercury content in the Emory and Clinch River sediments near the ash spill were slightly elevated (up to a factor of 3) at certain locations compared to upstream sediments. Up to 2% of the total mercury in sediments containing coal ash was present as methylmercury. Mercury isotope composition and sediment geochemical data suggested that elevated methylmercury concentrations occurred in regions where native sediments were mixed with coal ash (e.g., less than 28% as coal ash in the Emory River). This coal ash may have provided substrates (such as sulfate) that stimulated biomethylation of mercury. The production of methylmercury in these areas is a concern because this neurotoxic organomercury compound can be highly bioaccumulative. Future risk assessments of coal ash spills should consider not only the leaching potential of mercury from the wastes but also the potential for methylmercury production in receiving waters. PMID:23249246

Deonarine, Amrika; Bartov, Gideon; Johnson, Thomas M; Ruhl, Laura; Vengosh, Avner; Hsu-Kim, Heileen

2013-02-19

126

Low-level radiation in coals utilized and ashes produced at New York State electric utilities  

International Nuclear Information System (INIS)

Eight coal-fired power plants in New York State were sampled for coal, fly ash and bottom ash. Samples were analyzed for uranium 238, uranium 235, uranium 234, thorium 232, thorium 230, radium 226, lead 210, polonium 210, radon 222. The leachate of six fly ash samples was analyzed for all of the above except radon 222. Some data on fly ash analysis are included

127

The future resources for eco-building materials: II. Fly ash and coal waste  

Energy Technology Data Exchange (ETDEWEB)

To use fly ash and coal waste effectively, the current technologies for reprocessing and recycling these wastes into eco-building materials were reviewed, such as utilizing fly ash as the component of fly ash cement and low heat cement after the processes of separation, removal of carbon remains and fine comminution, calcining coal waste into kaolin and meta-kaolin with suspension technology, and preparing clinkerless alkali-activated geopolymer materials with fly ash and meta-kaolin.

Hui Li; Delong Xu [Xi' an University of Architecture & Technology, Xi' an (China). China State key Laboratory of Western Architecture & Technology

2009-08-15

128

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

129

Volcanic ash in feed coal and its influence on coal combustion products  

Energy Technology Data Exchange (ETDEWEB)

The US Geological Survey and the University of Kentucky Center for Applied Energy Research are collaborating with an Indiana Utility to determine the physical and chemical properties of feed coal and coal combustion products (CCPs) from a coal-fired power plant. The plant utilizes a low-sulfur (.23--.47 weight percent S) coal from the Powder River Basin, Wyoming. Scanning Electron Microscope (SEM) and X-ray diffraction (XRD) analysis of feed coal samples identified two mineral suites. A primary suite (not authigenic) consisting of quartz (detrital and volcanic beta-form grains), biotite, and minor zircon and a secondary authigenic mineral suite containing calcite, alumino-phosphates (crandallite and gorceixite), kaolinite, quartz, anatase, barite, and pyrite. The authigenic minerals are attributed to air-fall and reworked volcanic ash that was deposited in peat-forming mires. The Powder River Basin feed coals contain higher amounts of Ba, Ca, Mg, Na, Sr, and P compared to other analyzed eastern coals. These elements are associated with alumino-phosphate, biotite, calcite, and clay minerals. The element associations are indicative of coal that incorporated volcanic ash during deposition. XRD analysis of CCPs revealed a predominance of glass, perovskite, lime, gehlenite, quartz, and phosphates with minor amounts of periclase, anhydrite, hematite, and spinel group minerals in the fly ash; and quartz, plagioclase (albite and anorthite), pyroxene (augite and fassaite), rhodonite, and akermanite in the bottom ash. Microprobe and SEM analysis of fly ash samples revealed quartz, zircon, monazite, euhedral laths of corundum with merrillite, hematite, dendritic spinels/ferrites, and rounded grains of wollastonite with periclase. The abundant Ca and Mg mineral phases in the fly ashes are related to the presence of carbonate, clay, and phosphate minerals in the feed coal. The Ca- and Mg-rich mineral phases in the CCPs can be attributed to volcanic minerals deposited in the peat-forming mire. Dissolution and alteration of these minerals occurred either in the peat-forming sate or during coalification/diagenesis contributing to the authigenic mineral suite. Additionally, detrital mineral input and epigenetic ground-water flow may have affected the geochemistry of the feed coal.

Brownfield, M.E.; Affolter, R.H.; Cathcart, J.D.; Brownfield, I.K.; Hower, J.C.; Stricker, G.D.; O' Connor, J.T.

2000-07-01

130

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 concr...

Kae-Long Lin; Ju-Ying Lan

2013-01-01

131

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

132

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

133

Coal-ash Corrosion of Alloys for Combustion Power Plants  

Energy Technology Data Exchange (ETDEWEB)

A program on coal-ash corrosion is being conducted at Argonne National Laboratory to evaluate the performance of several structural alloys in the presence of mixtures of synthetic coal ash, alkali sulfates, and alkali chlorides. Candidate alloys are also exposed in a small-scale coal-fired combustor at the National Energy Technology Laboratory in Pittsburgh. Experiments in the present program, which addresses the effects of deposit chemistry, temperature, and alloy chemistry on the corrosion response of alloys, were conducted at temperatures in the range of 575-800 C for time periods up to {approx}1850 h. Fe-base alloys selected for the study included HR3C, 310TaN, HR120, SAVE 25, NF709, modified 800, 347HFG, and HCM12A. In addition, 800H clad with Alloy 671 was included in several of the exposures. Ni-base alloys selected for the study included 600, 601, 617, 690, 625, 602CA, 214, 230, 45TM, HR 160, and 693. Data were obtained on weight change, scale thickness, internal penetration, microstructural characteristics of corrosion products, mechanical integrity of the scales, and cracking of scales. Results showed that the relationship of corrosion rates to temperature followed a bell-shaped curve for Fe-base alloys, with peak rates at {approx}725 C, but the rate itself was dependent on the alloy chemistry. Several Fe-base alloys showed acceptable rates in the sulfate-containing coal-ash environment; but NaCl in the deposit led to catastrophic corrosion at 650 and 800 C. Ni-base alloys generally exhibited less corrosion than the Fe-base alloys under similar exposure conditions; however, they were susceptible to localized corrosion in the form of pits.

Natesan, K.; Purohit, A.; Rink, D.L.

2003-04-22

134

Geotechnical Properties of Some Coal Fly Ash Stabilized Southwestern Nigeria Lateritic Soils  

Directory of Open Access Journals (Sweden)

Full Text Available This study on stabilization of tropical lateritic soils using self-cementing coal fly ash evaluated the effects of the addition of self-cementing coal fly ash on the engineering properties of three lateritic soils from southwestern Nigeria. The engineering properties investigated were those normally involved in highway design and construction. Increasing percentages (by weight of dry soil of coal fly ash, ranging from 0% through 15% in 2.5% increments, were added and the geotechnical properties assessed. It was observed, for all the soils, that increasing coal fly ash contents brought about increasing improvements in the plasticity and mechanical properties of the soils. When comparing the average value of the properties at 0% coal ash content to their average values at 12.5% coal ash content, there was a reduction in the liquid limits (from 39% to 33%, a reduction in the plasticity indices (from 15.3% to 9.3%, a reduction in the optimum moisture contents (from 15.8% to 9.7% accompanied by an increase in the maximum dry densities (from 1920 to 2200 kg/m3, and an increase in the unsoaked CBR values (from 20% to 55.3%. For the stabilization of lateritic soils with coal fly ash, a coal fly ash of 12.5% by weight of dry soil was recommended because the improvements in the soil’s properties tapered off at about that percentage of coal ash content.

Emmanuel Akintunde Okunade

2010-11-01

135

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 SciELO Brazil | Language: Portuguese Abstract in portuguese [...] 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

136

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 SciELO Brazil | Language: Portuguese Abstract in portuguese [...] 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.

137

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

Science.gov (United States)

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 M(n) [-(Si-O)(z)-Al-O](n).wH(2)O, that forms during the alkaline activation, was examined by means of microcalorimetry, XRD, TGA, DSC, MIP, FTIR, NMR MAS ((29)Si, (27)Al, (23)Na), 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 86.2kJ/mol. The X-ray diffraction analysis revealed no additional crystalline phases associated with geopolymer formation. Over several weeks, the (29)Si NMR spectrum testified a high degree of polymerization and Al penetration into the SiO(4) tetrahedra. The (23)Na NMR MAS spectrum hypothesized that sodium is bound in the form of Na(H(2)O)(n) rather than Na(+), thus causing efflorescence in a moisture-gradient environment. As and Cr(6+) are weakly bonded in the geopolymer matrix, while excellent immobilization of Zn(2+), Cu(2+), Cd(2+), and Cr(3+) are reported. PMID:19303704

Skvára, Frantisek; Kopecký, Lubomír; Smilauer, Vít; Bittnar, Zdenek

2009-09-15

138

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.

139

Synthesis of high ion exchange zeolites from coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

This study focuses on the synthesis at a pilot plant scale of zeolitic material obtained from the coal fly ashes of the Teruel and Narcea power plants in Spain. After the optimisation of the synthesis parameters at laboratory scale, the Teruel and Narcea fly ashes were selected as low and high glass fly ashes. The pilot plant scale experiments were carried out in a 10 m{sup 3} reactor of Clariant SA (Barcelona, Spain). The results allowed obtaining 1.1 and 2.2 tonnes of zeolitic material with 40 and 55% of NaP1 content, in two single batch experiments of 24 and 8 hours, for Teruel and Narcea fly ashes, respectively. The cation exchange capacities (CEC) of the final product reached 2.0 and 2.7 meq g{sup -1} for Teruel and Narcea zeolitic material, respectively, which are very close to the usual values reached by the high quality natural zeolitic products. Finally, with the aim of testing possible applications of the commercial NaP1-IQE and pilot plant NaP1-Narcea zeolitic products in water decontamination, efficiency for metal uptake from waste waters from electroplating baths was investigated.

Querol, X.; Moreno, N.; Alastuey, A.; Juan, R.; Andres, J.M.; Lopez-Soler, A.; Ayora, C.; Medinaceli, A.; Valero, A. [CSIC, Barcelona (Spain)

2007-07-01

140

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

 
 
 
 
141

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

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

On-stream coal ash analysis based on natural gamma ray activity  

International Nuclear Information System (INIS)

The paper briefly reviews the recent progress in the development of on-stream coal ash analysers based on natural gamma ray activity. The technique is based on the correlation between the ash content and the natural gamma ray activity of coal due to the presence of potassium and the daughter products of uranium and thorium. Laboratory studies of the relationship between ash content and the natural gamma ray activity of bituminous, subbituminous and lignitic coals have established that the ash content of coal can be predicted from gamma ray activity with acceptable accuracy. Coal ash analysers based on natural gamma ray activity have been successfully developed and field tested in Australia, the Union of Soviet Socialist Republics and the United Kingdom. Ash analysers are commercially manufactured in Australia and in the UK. Natural gamma ash analysers are inexpensive compared with other ash analysers, free of artificial radiation sources, relatively insensitive to variations in ash composition and require only slow electronics. A disadvantage of natural gamma ash analysers is that coal from seams of different source materials, deposit environment and geological history may require different calibration equations. These ash analysers can operate directly under plate feeders or under conveyor belts. However, surface profiling is required for accurate results on a conveyor belt. (author). 15 refs, 3 figs, 1 tab

144

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

145

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

146

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

147

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

International Nuclear Information System (INIS)

Main obstacle using of fly ashes in building, that is its main consumer, is the residue of unburned coal; it is expressed of loss on ignition - 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 utilization of individual products obtained by modification. By means of corona separation, based on different conductivity of individual fly ash elements, it is possible to separate unburned coal particles. The fly ash sample from black coal burning in melting boiler that was deposited on fly ash deposit, content of LOI of dielectric particle 6,45 % at 61 % weight yield was achieved. In the samples taken from dry taking of fly ash the non-conducting product contained 7,72 % of LOI at 73 % of weight yield. (authors)

148

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

149

Natural Radionuclides in Slag/Ash Pile from Coal-Fired Power Plant Plomin  

International Nuclear Information System (INIS)

Full text: The coal slag/ash pile contains about one million tons of different (bottom ash, filter ash, gypsum) waste material deposited in vicinity of Plomin coal-fired power plant. Activities of 40K, 228Ra, 226Ra and 238U in materials deposited on slag/ash pile as well as in used coals were occasionally measured during past more than two and half decades of Plomin coal-fired plant operation. The radionuclides content in deposited bottom and filter ash material are related with radionuclide activities and mineral matter fraction in coals used. Up to the middle of nineties, the majority of coal used was anthracite from Istrian local mines. In that period, deposited waste material was characterised with relatively high 226Ra and 238U activities while potassium and thorium content was very low. When Istrian coal has been completely substituted with imported coal, uranium series radionuclide concentrations in deposited waste materials decreased significantly. Meanwhile, potassium and thorium activities in slag/ash pile material increased. It seems that slag/ash pile material generated in the last several years of Plomin coal-fired power plant operation could be generally used in cement industry without any special restriction. (author)

150

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

151

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

152

Sodium and oxygen in Nigerian coals: Possible effects on ash fouling  

Energy Technology Data Exchange (ETDEWEB)

Ash fouling during heat transfers in coal power-plants has been known to be an engineering problem caused by high sodium levels of the feed-coals. Instrumental Neutron Activation Analysis (INAA) was used in determining the concentration of some alkali elements (Na, Ca, Mg) associated with ash fouling for eight Nigerian coals mined at Onyeama, Ogbete, Enugu, Gombe, Okaba, Afikpo, Lafia and Asaba. Sodium levels were generally low (0.001-0.036%). Oxygen concentrations considered as an indicative measure of the wettability of each of the coals were determined. The possible effects of the concentration of these elements on ash fouling were discussed. 8 refs., 3 tabs.

Ewa, I.O.B.; Elegbe, S.B.; Adetunji, J. [Ahmadu Bello Univ., Zaria (Nigeria)

1996-09-01

153

On-line determination of ash in coal using 'SIROASH' gauges  

International Nuclear Information System (INIS)

The CSIRO has developed two SIROASH gauges for on-line determination of the ash content of coal. The first, based on low energy gamma-ray transmission (LET), is the preferred technique for low ash coals. It can be readily used directly on a conveyor belt provided the coal thickness exceeds about 50mm. In a two month plant trial the LET gauge determined the ash content of coal on the final product conveyor to +-0.45 wt%. Laboratory experiments on 1-2kg product, and in one case feed, coking coal samples determined ash to 0.31-0.40 wt %. The second technique, based on a high energy gamma-ray interaction called pair production (PP), is less sensitive to variations in ash composition and is the preferred technique for high ash coals. Laboratory tests on 50kg samples of high ash coals gave errors of 0.46-1.3 wt% ash compared to 1-2.2wt% for the LET gauge on the same samples

154

Adsorption of indigo carmine from aqueous solution using coal fly ash and zeolite from fly ash  

International Nuclear Information System (INIS)

Coal fly ash, a waste generated at the Figueira coal-fired electric power plant located in Brazil, was used to synthesize zeolite by hydrothermal treatment with NaOH solution at 100 deg C for 24 h. The fly ash (FA) and this synthesized zeolite (ZM) that was characterized predominantly as hydroxy-sodalite were used as adsorbents for anionic dye indigo carmine from aqueous solutions. The samples were analyzed by instrumental neutron activation analysis (INAA) for the determination of As, Co, Fe, La, Mo, Na, Sb, Sc, Sm, Th, U and Zn. Effects of contact time and initial dye concentration were evaluated in the adsorption processes. 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 Langmuir isotherm model provided the best correlation of the experimental data. The maximum adsorption capacity was found to be 1.48 mg L-1 for FA and 1.23 mg L-1 for ZM. Laboratory leaching and solubilization tests conducted to classify this ZM as if was a waste residue according to the Brazilian regulation classified it as a residue non-hazardous and non-inert. (author)

155

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

156

Design and testing controlled low-strength materials (CLSM) using clean coal ash  

Energy Technology Data Exchange (ETDEWEB)

The major objective of this project was to develop mixture proportions for controlled low-strength material (CLSM) using clean coal ash obtained from atmospheric fluidized bed combustion (AFBC). A clean coal ash is defined as the ash derived from SO{sub x} and NO{sub x} control technologies. The specific ashes used for this project were: (1) circulating fluidized bed boiler fly ash and bottom ash and (2) stoker-type boiler fly ash and bottom ash. These two coal ash samples were characterized for physical and chemical properties. Chemical properties and water leaching tests were also performed on the hardened CLSM. Many initial CLSM mixtures were developed by blending the two types of ash. Tests conducted on the final three selected CLSM mixtures included compressive strength, bleeding, setting and hardening, settlement, length change of hardened CLSM, permeability, mineralogy, and chemical water leach testing. Results show that acceptable CLSM material can be developed by blending the fluidized bed boiler ash with the stoker boiler ash. Recommendations for a pilot scale manufacturing application of the three CLSM mixtures were made based upon the lab test results.

Naik, T.R.; Kraus, R.N. [Univ. of Wisconsin, Milwaukee, WI (United States); Sturzl, R.F. [Manitowoc Public Utilities, WI (United States); Ramme, B.W. [Wisconsin Electric Power Co., Milwaukee, WI (United States)

1998-10-01

157

Determination of radioactive trace elements in ashes and fly-ashes from Brazilian coal-fired power plants  

International Nuclear Information System (INIS)

The aim of this work was to apply a epithermal neutron activation technique to determine the uranium and thorium content in coal ashes and fly ashes from Brazilian coal-fired thermoelectric plants and to evaluate the contribution of these elements and their descendents to the environmental radioactivity. Brazil has adopted as short term policy the use of alcohol and coal as alternative sources of energy. With regard to coal, large deposits of this mineral are found in southern states but the serious problem of its utilization is the risk of environmental contamination which can reach dangerous levels because the industrial plants burn several million tons per year. Uranium and thorium contents, determined experimentally, are extrapolated for annual coal consumption and their amounts and the activity of the radium isotopes descendents released to the atmosphere are calculated. The significance of these values and problems in environmental pollution are discussed

158

Rheology of fly ashes from coal and biomass co-combustion  

DEFF Research Database (Denmark)

The presence of large amounts of alkali metals, chlorine and sulphur in most biomass fuels - compared to coal - can create serious ash-related problems such as deposition, agglomeration and/or corrosion. This paper discusses the viscosity characteristics of fly ash from the co-combustion of various coal/biomass blends in a pilot scale pf-boiler. The produced data provide information on the melting of the ash and its flow characteristics, as a function of temperature, which may be used to modify the temperature profile of the boiler in order to avoid slagging. Straw co-firing lowers the ash viscosity leading to higher stickiness of the ash particles. Wood co-firing has only minor effects, due to the composition of wood ash and the low percentage of wood in the coal/biomass blend.

Arvelakis, Stelios; Frandsen, Flemming

2010-01-01

159

Effects of sediment containing coal ash from the Kingston ash release on embryo-larval development in the fathead minnow, Pimephales promelas (Rafinesque, 1820).  

Science.gov (United States)

The largest environmental release of coal ash in US history occurred in December 2008 with the failure of a retention structure at the Tennessee Valley Authority Kingston Fossil Fuel 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 embryonic and larval life stages. The early development of fish embryos and larvae during contact exposures to river bottom sediments containing up to 78 % coal ash from the Kingston spill was examined in 7-day laboratory tests with the fathead minnow (Pimephales promelas). No significant effects were observed in hatching success, incidences of 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 a significant risk to fish eggs and larvae in waterways affected by the coal ash spill. PMID:24213590

Greeley, Mark S; Elmore, Logan R; McCracken, Mary K; Sherrard, Rick M

2014-02-01

160

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

 
 
 
 
161

Uranium content of coal ashes from Southern Brazil coal fueled power stations, by the fission track registration technique  

International Nuclear Information System (INIS)

The feasibility of the application of the fission track registration technique for the determination of uranium in coal ashes was shown. The wet method was employed using as detector the Makrofol KG=10 ?m, manufactured by Bayer. The coal ashes were originated from coal-fueled power stations localized in Southern Brazil. The results obtained ranged from 10 to 27 mg U/kg. Since the total error variation was from 18,4% to 23,8%, the method used was considered excellent. The determination of the uranium content in coal ashes is of considerable interest in environmental control in power stations, in their vicinity and wherever these ashes are used or stored. The technique used is the work proved to be very appropriate for the purpose aimed at. (Author)

162

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

163

Design and construction of gamma transmission gauge for determination of the ash content in coal  

International Nuclear Information System (INIS)

More than two years research work on design of a dual energy ?-ray transmission gauge is reviewed in this paper. The gauge after construction will be to install in a large coal industry named Kerman District Coal Mines (KDCM). KDCM consists of several coal mines, so that, coal transported on a conveyor belt may be a non-homogenious mixture from one or more mines. Therefore, prior to gauge design, primary investigation is done to identify and evaluate the relationship between the mass absorption coefficient (?-bar) and ash percent of coal for the mixture running on the belt. Results of investigation shows that, coal mixture calibration curve cannot be used accurately for ash estimation in coal of individual mines and, essentially, gauge may work to determine the ash percent with some limitations in this particular region. Therefore, design of gauge was carried out in the laboratory and after setting up, primary experimental calibration curve for the gauge is obtained. The r.m.s. difference between gauge ash and chemical assay is 1.17 wt% ash, for ash in the range of 32-44 (wt%). It is programmed for future to complete and improve the gauge to be able for on-line ash determinations. (author). 5 refs, 7 figs, 2 tabs

164

Dilithium dialuminium trisilicate Crystalline Phase Prepared from Coal Fly Ash  

Science.gov (United States)

The dilithium dialuminium trisilicate phase Li2Al2Si3O10 was prepared using coal fly ash and lithium hydroxide monohydrate LiOH·H2O as precursors. The influences of various preparation conditions on Li2Al2Si3O10 forming were investigated. The results showed that the optimum additive amount of LiOH·H2O was about 20%. The onset of calcining temperature and time was identified as 980 °C and 1 h, respectively. XRD analysis indicated that the content of Li2Al2Si3O10 phase increased at the expense of quartz and mullite, with calcining temperatures increasing and time extending. SEM observation revealed that the calcined samples were drastically interlocked together with the prolonging of time. The obtained Li2Al2Si3O10 phase was well crystallized and with small grain size.

Yao, Zhitong; Xia, Meisheng; Ye, Ying

2012-06-01

165

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

Energy Technology Data Exchange (ETDEWEB)

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 M{sub n} [-(Si-O){sub z}-Al-O]{sub n}.wH{sub 2}O, that forms during the alkaline activation, was examined by means of microcalorimetry, XRD, TGA, DSC, MIP, FTIR, NMR MAS ({sup 29}Si, {sup 27}Al, {sup 23}Na), 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 {sup 29}Si NMR spectrum testified a high degree of polymerization and Al penetration into the SiO{sub 4} tetrahedra. The {sup 23}Na NMR MAS spectrum hypothesized that sodium is bound in the form of Na(H{sub 2}O){sub n} rather than Na{sup +}, thus causing efflorescence in a moisture-gradient environment. As and Cr{sup 6+} are weakly bonded in the geopolymer matrix, while excellent immobilization of Zn{sup 2+}, Cu{sup 2+}, Cd{sup 2+}, and Cr{sup 3+} are reported.

Skvara, Frantisek, E-mail: skvaraf@vscht.cz [ICT Prague, Faculty of Chemical Engineering, Department of Glass and Ceramics, 166 28 Prague 6, Technicka 5 (Czech Republic); Kopecky, Lubomir, E-mail: kopecky@fsv.cvut.cz [Czech Technical University in Prague, Faculty of Civil Engineering, Department of Mechanics, 166 29 Prague 6, Thakurova 7 (Czech Republic); Smilauer, Vit, E-mail: vit.smilauer@fsv.cvut.cz [Czech Technical University in Prague, Faculty of Civil Engineering, Department of Mechanics, 166 29 Prague 6, Thakurova 7 (Czech Republic); Bittnar, Zdenek, E-mail: bittnar@fsv.cvut.cz [Czech Technical University in Prague, Faculty of Civil Engineering, Department of Mechanics, 166 29 Prague 6, Thakurova 7 (Czech Republic)

2009-09-15

166

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

167

Automated semiquantitative direct-current-arc spectrographic analysis of eight argonne premium coal ash samples  

Science.gov (United States)

The automated semiquantitative direct-current-arc spectre-graphic method was used to analyze 62 elements in eight Argonne Premium Coal Ash samples. All eight coal ash samples were analyzed in triplicate to verify precision and accuracy of the method. The precision for most elements was within ??10%. The accuracy of this method is limited to +50% or -33% because of the nature of the standard curves for each of the elements. Adjustments to the computer program were implemented to account for unique matrix interferences in these particular coal ash samples.

Skeen, C. J.; Libby, B. J.; Crandell, W. B.

1990-01-01

168

Reduction of metal leaching in brown coal fly ash using geopolymers  

Energy Technology Data Exchange (ETDEWEB)

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 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.

Bankowski, P. [School of Engineering and Technology, Deakin University, Geelong, Vic. 3217 (Australia)]. E-mail: bankowsk@deakin.edu.au; Zou, L. [School of Engineering and Technology, Deakin University, Geelong, Vic. 3217 (Australia); Hodges, R. [School of Applied Science, Monash University, Churchill, Vic. 3842 (Australia)

2004-10-18

169

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

170

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

171

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)

172

Adsorption of anionic dyes from aqueous solutions onto coal fly ash and zeolite synthesized from coal fly ash  

International Nuclear Information System (INIS)

Coal fly ash, a waste generated in coal-fired electric power plant, was used to synthesize zeolite by hydrothermal treatment with NaOH solution. The fly ash (CL-2) and this synthesized zeolite (ZM-2) that was characterized as hydroxy-sodalite were used as adsorbents for anionic dyes indigo carmine (IC), and reactive orange 16 (RO16) from aqueous solutions. Effects of contact time, initial dye concentration, pH, adsorbent mass, and temperature were evaluated in the adsorption processes. 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. The thermodynamics parameters demonstrated that the adsorption was spontaneous for all adsorption processes. The enthalpy data confirmed the endothermic nature for all adsorption processes except for IC/ZM-2 system which was exothermic. The entropy data showed an increased disorder at the solid/solution interface during the adsorption for all systems except for IC/ZM-2 whose negative entropy value indicated a decreased disorder at the interface. The adsorption isotherms were closely fitted to the Langmuir linear equation. The maximum adsorption capacities were 1.48 mg/g for the IC/CL-2 system; 1.13 mg/g for IC/ZM-2; 0.96 mg/g for RO16/CL-2, and 1.14 mg/g for RO16/ZM-2 at room temperature. The desorption study carried out with water, with acid aqueous solutions, and with an alkali aqueous solution showed to be inefficient both for recovering the dyes and regenerating the adsorbents. (author)

173

Behaviour of alkaline and heavy metals in coal-fired combined processes with pressurized coal dust combustion - a thermodynamic approach; Das Verhalten von Alkali- und Schwermetallen in kohlebefeuerten Kombiprozessen mit Druckkohlenstaubfeuerung (DKSF) - Ein thermodynamischer Ansatz  

Energy Technology Data Exchange (ETDEWEB)

The process intends direct expansion of hot-pressure-charged flue gas, with temperatures above 1200 C via a gas turbine. Coal combustion takes place at temperatures of 1500 - 1700 C and 10-16 bar. At this high process temperature level, volatile alkaline and heavy metal compounds are released which condense on the gas turbine blades and may cause corrosion. A thermodynamic process model is presented for alkaline metal and heavy metal release and for alkali metal separation. The model uses thermodynamic data of more than 600 components and includes the non-ideal interactions between ash components. The set of thermodynamic data can be transferred to the conditions of atmospheric dust combustion and cocombustion. Results of the thermodynamic calculations of alkaline and heavy metal release and alkaline metal capture are presented as well as an assessment of the corrosion hazard on the gas turbine blades. (orig.)

Bause, T.; Meyer, B. [TU Bergakademie Freiberg (Germany)

2004-07-01

174

Properties of coal ash mixtures and their use in highway embankments  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Class F fly ash and bottom ash are the solid residue by-products produced by coal-burning electric utilities. They are usually disposed of together as a waste in utility disposal sites with a typical disposal rate of 80% fly ash and 20% bottom ash. The fly and bottom ash accumulated daily in disposal areas have been a significant concern to utility companies, and is fast becoming a social problem. Direct use of these materials in construction projects consuming large volumes of materials, suc...

Kim, Bumjoo

2003-01-01

175

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

176

Mineral conversion and microstructure change in the melting process of Shenmu coal ash  

Energy Technology Data Exchange (ETDEWEB)

China has rich reserves of Shenmu coal, which has the typical characteristic of low-melting-point ash. If used in the pulverized-coal boiler of a power plant, Shenmu coal would cause serious slagging. In order to solve the slagging problem of Shenmu coal, the melting mechanism of Shenmu coal ash was studied. One of the Shenmu coals - Wenjialiang coal - was selected for the study. Using thermogravimetry-differential scanning colorimetry (TG-DSC) methods, the change of the coal ash's physicochemistry with temperature was studied. The typical temperature points in the melting process were obtained. Ash samples of the different temperature points were prepared in a high-temperature furnace with parameters similar to those used in the TG-DSC test, and were then cooled quickly in water. Later, the ash samples were analyzed using X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX) methods in detail. Wenjialiang coal ash started to melt at 980{sup o}C. The ash was found to melt to a great extent at 1200{sup o}C and formed a multiform microstructure. At 1260{sup o}C, it was found to melt into a dense body with many pores, and formed a piece of vitreous body at 1340{sup o}C. Anorthite and gehlenite are the intermediate products that exist between 980 and 1340{sup o}C. They may be the main cause of the ash having low melting points, so that they could convert into a eutectic at low temperatures.

Yang Jianguo; Deng Furong; Zhao Hong; Cen Kefa [Zhejiang University, Hangzhou (China). State Key Laboratory of Clean Energy Utilization

2007-05-15

177

A study of afforestation on coal ash reclaimed land and refuse heap and the environmental impact  

Energy Technology Data Exchange (ETDEWEB)

Describes afforestation of the Huaibei power plant ash disposal site (ground depression filled with a 5 m thick ash layer) and a conical coal mining spoil bank. The ash disposal site was covered with 30 cm of topsoil; the spoil bank, composed of 70% fine grain fractions as a result of 30 years of weathering, was terraced as a spiral. The afforestation sites were irrigated with mine drainage water. Chemical composition of the ash and coal mining waste is provided. About 200 species of trees were planted; tree growth was monitored over 6 years. The most suitable trees were yellow locust, chinaberry, torch tree, poplar and elm. Application of fertilizer is regarded as important for tree growth. The mean annual tree growth was 1.29-1.86 m. The spread of root systems in coal ash and in mining waste is evaluated. Afforestation reduced air and ground temperature at the forest site and produced 52 t/a of biomass per hectare.

Shuli, Z.; Qifeng, Z.; Qichang, X.; Zhenqi, H. (Mining Administration, Huaibei (China). Forestation Division)

1993-01-01

178

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)

179

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

180

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

 
 
 
 
181

Secondary Industrial Minerals from Coal Fly Ash and Aluminium Anodising Waste Solutions:  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Minerals that are extracted from the earth’s crust to be directly used for their properties are called industrial minerals. This research shows that such minerals can also be produced from industrial residues, hence the name secondary industrial minerals. In this thesis coal fly ash is chosen as one of the industrial residues to work with. Since reuse of coal fly ash is restricted by its technical and environmental quality, the first approach was to improve its quality and thereby exten...

Nugteren, H. W.

2010-01-01

182

Study on intensified leaching of germanium and uranium in coal ash  

International Nuclear Information System (INIS)

This paper describes the results of laboratory test processing uranium and germanium-bearing coal ash by intensified leaching with sulfuric acid-compound A, focuses discussion on influence of process factors on germanium leaching rate, and presents the optimum leaching parameters of two-stage countercurrent. It is shown in the results that the method is not only technically feasible but economically reasonable. It is a efficient method for processing refractory coal ash

183

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

184

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

185

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

186

De-ashing of coal by oil agglomeration in an experimental washing column  

Energy Technology Data Exchange (ETDEWEB)

The operation of a de-ashing column for a coal slurry flocculated with an oil is described. Some qualitative observations relative to the parameters affecting the conditioning of the slurry are also included. De-ashing efficiency, carbon recovery and specific water consumption are presented in the form of diagrams. 6 figures, 3 tables.

Bonapace, A.C.; Stylianides, T.S.

187

The de-ashing of coal by oil agglomeration in an experimental washing column  

Energy Technology Data Exchange (ETDEWEB)

The operation of a de-ashing column for a coal slurry flocculated with an oil is described. Some qualitative observations relative to the parameters affecting the conditioning of the slurry are also included. De-ashing efficiency, carbon recovery and specific water consumption are presented in the form of diagrams. (1 ref.)

Bonapace, A.C.; Stylianides, T.S.

1978-01-01

188

De-ashing of coal by oil agglomeration in an experimental washing column  

Energy Technology Data Exchange (ETDEWEB)

The operation of a de-ashing column for a coal slurry flocculated with an oil is described. Some qualitative observations relative to the parameters affecting the conditioning of the slurry are also included. De-ashing efficiency, carbon recovery and specific water consumption are presented in the form of diagrams.

Bonapace, A.C.; Stylianides, T.S.

1978-06-01

189

De-ashing of coal by oil agglomeration in an experimental washing column  

Energy Technology Data Exchange (ETDEWEB)

The operation of a de-ashing column for a coal slurry flocculated with an oil is described. Some qualitative observations relative to the parameters affecting the conditioning of the slurry are also included. De-ashing efficiency, carbon recovery and specific water consumption are presented in the form of diagrams. This paper in concluded in this issue.

Bonapace, A.C.; Stylianides, T.S.

1978-08-01

190

Importance of the radiometric ash content determination by means of beta backscattering for coal transformation  

International Nuclear Information System (INIS)

The radiometric method for ash content determination based on beta backscattering has been evaluated from the point of view of quality control and quality assurance in lignite mining and use of lignite. Applying the method, optimum control and distribution to generation of power, briquetting or coal transformation depending on ash content is possible

191

Influence Of Trace Metal Distribution On Its Leachability From Coal Fly Ash  

Science.gov (United States)

The risks associated with the reuse of coal fly ash in natural environmental settings in terms of their mobility and ecotoxicological significance is largely determined by: (1) the physicochemical conditions the fly ash is placed under; (2) the total leachable metal content in fl...

192

Dynamic formation of zeolite synthesized from fly ash by alkaline hydrothermal conversion.  

Science.gov (United States)

This study was designed to characterize the dynamic formation of zeolite synthesized from fly ash (ZFA) and to identify the zeolitization mechanisms during a 160-h-long hydrothermal alkaline conversion at 95°C by using fly ash (FA) samples collected from four typical thermoelectric power plants in China, with the purpose of improving ZFA quality. The process of synthesizing ZFA can be fundamentally divided into five stages: induction stage (0-0.5 h), accelerating dissolution stage (0.5-12 h), nucleation and/or crystallization stage (12-24 h), crystal growth stage (24-72 h) and crystal transformation stage (72-160 h). The crystal growth stage determined the quality of zeolite crystallization, coupled with functions of re-assembling the silicon-aluminium tetrahedral network and developing submicro- and/or nanometer microstructure. A 48-h-long hydrothermal conversion generated ZFAs that had a greater specific surface area (26.0-89.4 times) and cation exchange capacity (29.6-71.0 times) than FA, which successfully sequestrated 41-95% of ammonium and 75-98% of phosphate from swine manure. However, over-reaction resulted in more stable hydroxysodalite and/or sodalite, surface agglomeration and cracking, and energy wasting. This work suggests that the reuse of recycled synthesis materials should occur during the fourth step (24-72 h). PMID:24025368

Zhang, ZhiJian; Li, Jiangli; Li, Hongyi; Wang, Hang; Zhu, Jun; He, Qiang

2013-11-01

193

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

194

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

195

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)

196

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.

197

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

Directory of Open Access Journals (Sweden)

Full Text Available 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

2012-03-01

198

Comparison of hemolytic activities of coal fly ash and its soluble and insoluble fractions  

Energy Technology Data Exchange (ETDEWEB)

Coal fly ash of a particle diameter smaller than 10 ..mu..m was collected from the precipitator of a power plant in Hong Kong. Comparison of hemolytic activities between fly ash and free silica showed that fly ash had a lower biological effect than free silica. The hemolytic activities of the soluble and insoluble fractions of fly ash were further compared by two methods: total hemoglobin method and cyanmethemoglobin method. An analysis of results showed significant differences for fly ash and its soluble fraction between methods. Fly ash, which contained a silicate level similar to its insoluble fraction, had a hemolytic activity higher than the summation of both its soluble and insoluble fractions. This indicates that the hemolytic activity was independent of the silicate content in the fly ash samples.

Liu, W.K.; Wong, M.H.; Tam, N.F.Y.

1986-08-01

199

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...

200

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

 
 
 
 
201

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

202

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

203

Remediation of coastal marine sediments using granulated coal ash  

Energy Technology Data Exchange (ETDEWEB)

It is very important to reduce phosphorus flux from sediment as well as cutting down terrigenous loads in order to control eutrophication in semi-enclosed coastal seas. Hydrogen sulfide is also a noxious substance which is highly toxic and fatal to benthic organisms. The purpose of this study is to evaluate remediation efficiency of organically enriched sediments using granulated coal ash (GCA) in terms of reducing benthic phosphorus flux and hydrogen sulfide. A flow-through experimental system was used to simulate the semi-enclosed water bodies. The application of GCA decreased the concentration of PO{sub 4}{sup 3-} in the pore water effectively, and reduced phosphate releasing flux from the sediment into overlying water by 37-44% compared to the control. The hydrogen sulfide in the pore water was also decreased by 77-100%, due to adsorption onto the GCA and deactivation of sulfate-reducing bacteria due to increasing pH. Thus, GCA is a promising recycled material for reducing phosphate releasing flux from organically enriched sediment to alleviate eutrophication as well as reduce the concentration of hydrogen sulfide in pore water.

Asaoka, S.; Yamamoto, T.; Yoshioka, I.; Tanaka, H. [Hiroshima University, Higashihiroshima (Japan)

2009-12-15

204

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 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.)

205

Co-combustion of coal and sewage sludge: chemical and ecotoxicological properties of ashes.  

Science.gov (United States)

The co-combustion of sewage sludge (SS) and coal is widely used for the treatment and thermal valorization of SS produced in wastewater treatment plants. The chemical and ecotoxicological properties of the ashes produced in this thermal treatment have not been fully studied. Two combustion tests were performed in a fluidized bed combustor. Colombian coal was used as fuel in test A. A blend (1+1) of this coal and a stabilized SS (Biogran) was used in a second test B. Samples of the bottom and fly ashes trapped in two sequential cyclones were collected. The characterization of the ashes was focused on two main aspects: (1) the bulk content of a set of metals and (2) the characterization of eluates produced according to the European Standard leaching test EN 12457-2. The eluates were submitted to an ecotoxicological characterization for two bio-indicators. In what concerns the bulk content of ashes, both combustion tests have produced ashes with different compositions. The ashes formed during the co-combustion test have shown higher concentrations of metals, namely Cr, Cu, Ni, Pb, Zn and Fe for all ashes. The leaching test has shown low mobility of these elements from the by-products produced during the combustion and co-combustion tests. Cr and Cr(VI) were mainly detected in the eluates of the 1st cyclone ashes produced in both combustion tests and in the 2nd cyclone ashes produced in the co-combustion test. Considering the ecotoxicity assays, the eluates of bottom and fly ashes for both combustion and co-combustion tests have shown low ecotoxic levels. The micro-crustacean Daphnia magna was generally more sensitive than the bacterium Vibrio fischeri. CEMWE criterion has allowed to classify the bottom ashes for both combustion and co-combustion tests as non-toxic residues and the fly ashes collected in both cyclones as toxic. PMID:19515486

Barbosa, Rui; Lapa, Nuno; Boavida, Dulce; Lopes, Helena; Gulyurtlu, Ibrahim; Mendes, Benilde

2009-10-30

206

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...

207

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)

208

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.)

209

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)

210

Natural radioactive level in coal and ash and building material products from coal-fired power plants in Beijing  

International Nuclear Information System (INIS)

The authors report the methods and results of survey on content of 226Ra, 232Th and 40K in samples of coal, ash from 5 coal-fired power plants in Beijing and ash bricks, air-added concrete from Beijing air-added concrete plant from February to December, 1993. 55 coal Samples, 26 ash Samples, 8 ash brick samples and 8 air-added concrete samples were collected. These samples were analysed by type FH-1936 low background ?-spectrometer. The average value of 226Ra, 232Th and 40K of coal is 28.9, 35.9 and 80.4 Bq/kg, respectively; 101, 110 and 347 Bq/kg, for ash; 47.6, 72.9 and 288 Bq/kg, for ash brick and 47.8, 70.1 and 216 Bq/kg for air-added concrete, respectively. In addition, ? radiation dose rate inside buildings of workers, dwelling houses of the Beijing air-added concrete plant made of ash building materials were investigated and analysed. The range and the average value of 8 measurement values is (67.4-84.7) nGy/h and 78.2 nGy/h, respectively. It approaches to the average value inside bungalow of bricks and a building of two or more storeys made of bricks and concrete in Beijing and within normal range. The results show that it might not cause obviously increase of ? radiation dose rate inside building when the ash were rationally used as the raw materials of building

211

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 con...

František Ka?avský; Vladimír Bláha

2008-01-01

212

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)

213

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

214

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

215

Comparison of heterogeneous photolytic reduction of Hg(II) in the coal fly ashes and synthetic aerosols  

Science.gov (United States)

In this study, we examined the heterogeneous reduction of Hg(II) on the coal fly ash samples and synthetic aerosols under different light conditions in a controlled laboratory reactor. Three types of coal fly ashes were studied: a high carbon fly ash from a stoker boiler, a low carbon/low sulfate fly ash from a pulverized coal combustor burning low sulfur coal, and a high sulfate fly ash from a pulverized coal combustor burning high sulfur coal. The rate of Hg(II) reduction on the three diverse fly ash samples was found to be relatively fast with an average half-life of 1.6 h under clear sky atmospheric conditions (under the irradiance of 1000 W/m2). The reduction rate in the low sulfate/low carbon fly ash was approximately 1.5 times faster than with the other coal fly ash samples. Synthetic aerosols made of carbon black and levoglucosan produced Hg(II) reduction rates similar to coal fly ashes. However, aerosols composed of adipic acid resulted in reduction rates that were 3-5 times faster. The sensitivity of adipic acid reduction to light source wavelength was found to be greater than for the coal fly ash and other synthetic aerosols. Aerosols made from the water extracts of coal fly ash samples produced reduction rates equal to or slightly higher than with the native fly ash suggesting that the soluble components of fly ash play a significant role in the reduction mechanism. The measured reduction rates are likely important in the chemical processing of mercury in power plant plumes and potentially in the atmosphere and should be considered for incorporation in atmospheric transport models that are used to understand the fate of atmospheric mercury.

Tong, Yindong; Eichhorst, Terry; Olson, Michael R.; Rutter, Andrew P.; Shafer, Martin M.; Wang, Xuejun; Schauer, James J.

2014-03-01

216

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

217

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

218

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)

219

Mercury in coals and fly ashes from Republika and Bobov dol thermoelectric power plants  

Science.gov (United States)

Feed coal and y ash samples were collected at Republika and Bobov Dol thermoelectric power plants (TPPs). The y ashes (FAs) were collected fromthree rows of the hot-side electrostatic precipitators (ESPs) array. Each sam- ple was wet-screened at 100, 200, 325 and 500 mesh. The coals and y 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 dierent 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 y ashes was also done in the present investigation.

Kostova, I.; Vassileva, C.; Hower, J.; Mastalerz, M.; Vassilev, S.; Nikolova, N.

2011-01-01

220

Behaviour of coal ashes for pulverised coal injection at high temperatures in relation to their chemical and mineralogical composition - experimental and computational analysis  

Energy Technology Data Exchange (ETDEWEB)

The selection of coals for pulverised coal injection usually consists of evaluating the carbonaceous matter. However, the reduction of permeability in the lower section of the blast furnace with high rates of pulverised coal injection can be associated with remaining ashes from the coal combustion process. The aim of this work is to evaluate the behaviour of coal ashes at high temperatures in relation to their chemical and mineralogical composition. These ashes were submitted to the following analysis: chemical (X-ray fluorescence), mineralogical (X-ray diffraction), fusibility (heating microscopy) and viscosity (rotational viscometer). The software FactSage was also used to evaluate the behaviour of coal ashes. It was observed that samples present different chemical and mineralogical compositions, reflecting in the fusibility and viscosity of ashes. Their proportions and relevant phases were determined by computational thermodynamics and also related to the experimental work.

Bagatini, M.C.; Klug, J.L.; Heck, N.C.; Osorio, E.; Vilela, A.C.F.; da Cruz, R. [Universidade Federal do Rio Grande do Sul, Porto Alegre (Brazil)

2009-11-15

 
 
 
 
221

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

International Nuclear Information System (INIS)

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 CaCO3 versus Al2O3 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. - Highlights: • Coal waste geochemisty can provide increased environmental information in coal-mining areas. • Oxidation is the major process for mineral transformation in coal ashes. • The electron bean methodology has been applied to investigate neoformed minerals

222

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

223

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)

224

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

225

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

Energy Technology Data Exchange (ETDEWEB)

Between 1955 and 1989, coal ash was deposited within an impounded watershed on the U.S. Department of Energy's Oak Ridge Reservation in Tennessee, creating the 3.6 ha Filled Coal Ash Pond (FCAP). The site has subsequently become vegetated wildlife habitat. To evaluate risks that metals in 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 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 its high sodium content, exposure experienced by deer consuming ash to meet sodium requirements was also estimated. 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, and deer consuming ash for sodium; foxes and hawks do not appear to be at risk.

Sample, B.E.; Suter, G.W. [CH{sub 2}M Hill Inc., Sacramento, CA (United States)

2002-07-01

226

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

227

Nitric oxide formation and release of alkaline substances during coal dust combustion under pressure; Stickoxidbildung und Alkalienfreisetzung bei der Kohlenstaubdruckverbrennung  

Energy Technology Data Exchange (ETDEWEB)

Coal dust combustion under pressure results in power plant process efficiency factors of 50% and more. After separation of the ash, which is liquid in this temperature range, the flue gas combusted under pressure is led into the gas turbine. The turbine function may be impaired by soiling with ash and by condensation of alkaline compounds. At the high combustion temperatures, thermally induced nitric oxide formation is non-negligible, but there is still potential for reduction which will also make the downstream denitrification procedure less complex and time-consuming. The potential is particularly high for combustion under pressure with its particular kinetic characteristics. (orig./AKF) [Deutsch] Die Druckkohlenstaubfeuerung erschliesst Kraftwerksprozesswirkungsgrade im Bereich von 50% und mehr. Dabei wird das unter Druck verbrannte Rauchgas nach der Abscheidung der Asche, die im benoetigten Temperaturbereich durchweg fluessig vorliegt, auf die Gasturbine geleitet. Neben der direkten Verschmutzung der Turbinenschaufeln mit Asche sind die Kondensationsvorgaenge von Alkalienverbindungen von besonderer Bedeutung fuer die Funktion der Turbine. Bei den verfahrensgemaess hohen Verbrennungstemperaturen ist die thermisch bedingte NO{sub x}-Bildung nicht mehr zu vernachlaessigen. Minderungspotentiale im Hinblick auf eine Senkung des nachfolgenden Entstickungsaufwandes sind jedoch noch nicht ausgeschoepft. Insbesondere die Druckverbrennung bietet aufgrund der kinetischen Besonderheiten ein Potential. (orig./AKF)

Pracht, M.; Thielen, W.

1997-12-31

228

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

229

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

230

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

231

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

Science.gov (United States)

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, a 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 species differences in the bioaccumulation of arsenic and selenium and potential factors contributing to these differences (i.e., trophic dynamics and gut pH) 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 24.83mg/kg dry weight and ovary concentrations up to 10.40mg/kg dry weight at coal ash-associated sites. Investigations into the gut pH and trophic dynamics of redear sunfish and bluegill 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 differences ((15)N and (13)C) 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. PMID:22947506

Otter, Ryan R; Bailey, Frank C; Fortner, Allison M; Adams, S Marshall

2012-11-01

232

Natural radiation in fly ashes from coal thermal power stations in Spain  

International Nuclear Information System (INIS)

Specific activity in samples of fly ashes from Spanish coal thermal power stations at Abono (Asturias), Andorra (Teruel), Alcudia (Mallorca) and Cercs (Barcelona) was analysed by gamma ray spectrometry. The values obtained permit us to quantify the presence of different natural radionuclides from /sup 232/Th, /sup 238/U, /sup 235/U series and /sup 40/K. The models are defined on the basis of these data to calculate the dosimetric impact caused by the use of fly ashes in the concrete

233

Natural radiation in fly ashes from coal thermal power stations in Spain  

Energy Technology Data Exchange (ETDEWEB)

Specific activity in samples of fly ashes from Spanish coal thermal power stations at Abono (Asturias), Andorra (Teruel), Alcudia (Mallorca) and Cercs (Barcelona) was analysed by gamma ray spectrometry. The values obtained permit us to quantify the presence of different natural radionuclides from /sup 232/Th, /sup 238/U, /sup 235/U series and /sup 40/K. The models are defined on the basis of these data to calculate the dosimetric impact caused by the use of fly ashes in the concrete.

Baro, J.; Sanchez-Reyes, A.; Chinchon, J.S.; Lopez-Soler, A.; Vazquez, E.; Yague, A.

1988-01-01

234

Effects of inhaled coal fly ash on lung biochemistry and function in guinea pigs  

International Nuclear Information System (INIS)

posures. It was previously found that exposure to 5 mg/M3 of Illinois No. 6 fly ash results in immediate reductions in pulmonary diffusing capacity (DLco), total lung capacity (TLC), and vital capacity, and that both DLco and TLC values are not completely restored to normal 96 h post-exposure. These results suggest that the alterations in pulmonary function resulting from exposure to acidic coal fly ash are not accompanied by major inflammatory changes in lavage fluid

235

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

236

Sewage sludge conditioning with coal fly ash modified by sulfuric acid  

Energy Technology Data Exchange (ETDEWEB)

Activated sludge process to treat municipal and industrial wastewater produces huge amounts of excess sludge. Chemical condition has been employed widely to improve sludge mechanical dewatering, but the cost is high, thus it is very important to find cheap and effective conditioners. This paper studied the improvement of sludge dewaterability with coal fly ash modified by sulfuric acid (MCFA). Through orthogonal experiments with specific resistance to filtration (SRF) as the target index, acid concentration and soaking time were verified to be the important influencing parameters in coal fly ash modification. The optimal modification conditions were: acid concentration, 4 mol l{sup -1}; ratio of acid to coal fly ash, 5:1 ml g{sup -1}; soaking time, 3 h. After modification the specific surface area of coal fly ash increased from 2.810 to 3.376 m{sup 2} g{sup -1}. The dewaterability and the settleability of the conditioned sludge were investigated with vacuum filtrating dewatering tests, centrifugal dewatering tests and settling experiments. The results showed that SRF of the sludge significantly decreased with coal fly ash addition, and the MCFA showed much stronger conditioning capacity than the raw coal fly ash (RCFA). Under a MCFA dosage of 273%, the SRF of the sludge decreased from 1.86 x 10{sup 13} to 4.23 x 10{sup 11} m kg{sup -1}, and the filter cake moisture decreased from 86.90% to 56.52%. The sludge conditioning mechanisms with MCFA mainly included improving floc formation through charge neutralization and adsorption bridging and providing the water transmitting passages by skeleton builder.

Chen, C.Y.; Zhang, P.Y.; Zeng, G.M.; Deng, J.H.; Zhou, Y.; Lu, H.F. [Beijing Forestry University, Beijing (China). College of Environmental Science & Engineering

2010-04-15

237

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.

238

ACUTE PULMONARY AND SYSTEMIC EFFECTS OF INHALED COAL FLY ASH IN RATS: COMPARISON TO AMBIENT ENVIRONMENTAL PARTICLES  

Science.gov (United States)

Although primary particle emissions of ash from coal-fired power plants are well controlled, coal fly ash (CFA) can still remain a significant fraction of the overall particle exposure for some plant workers and highly impacted communities. The effect of CFA on pulmonary and syst...

239

Laser Induced Breakdown Spectroscopy application for ash characterisation for a coal fired power plant  

International Nuclear Information System (INIS)

The aim of this work was to apply the LIBS technique for the analysis of fly ash and bottom ash resulting from the coal combustion in a coal fired power plant. The steps of presented LIBS analysis were pelletizing of powdered samples, firing with laser and spectroscopic detection. The analysis 'on tape' was presented as an alternative fast sampling approach. This procedure was compared with the usual steps of normalized chemical analysis methods for coal which are coal calcination, fluxing in high temperature plasma, dilution in strong acids and analyzing by means of ICP-OES and/or AAS. First, the single pulse LIBS approach was used for determination and quantification of elemental content in fly ash and bottom ash on the exit of the boiler. For pellet preparation, ash has to be mixed with proper binder to assure the sample resistance. Preparation of the samples (binder selection and pressing/pelletizing conditions) was determined and LIBS experimental conditions optimized. No preparation is necessary in 'on tape' sampling. Moreover, double-pulse approach in orthogonal reheating configuration was applied to enhance the repeatability and precision of the LIBS results and to surpass the matrix effect influencing the calibration curves in case of some elements. Obtained results showed that LIBS responses are comparable to the normalized analytical methods. Once optimized the experimental conditions and features, application of LIBS may be a promising technique for combustion process control even in on-line mode.

240

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

 
 
 
 
241

Multielement analysis of coal and coal fly ash standards by instrumental neutron activation analysis  

International Nuclear Information System (INIS)

Instrumental neutron activation analysis has been utilized for determining 39 major, minor and trace elements in the N.B.S. stanard reference materials coal: SRM-1632 and coal fly ash: SRM-1633. Recent literature on coal analysis is also reviewed. For most of the elements the irradiation standard used were either U.S.G.S. standard diabase rock W-1 or the N.B.S. standard reference material Orchard Leaves: SRM-1571. Two sets of irradiations were carried out. In the first or ''short'' irradiation, about 100-150 mg of samples and standards sealed in polyethylen vials were irradiated 1-2 min in the pneumatic transfer tube of Cornell TRIGA Mark II reactor at a thermal neutron flux 1x1012 cm-2s-1. In the second or ''long'' irradiation 200-300 mg of samples and standards sealed in high-purity quartz vials were irradiated for 8 hours in the central thimble facility of the same reactor at a thermal neutron flux of 3.5x1012 cm-2s-1. The samples and standards were counted on a coaxial 56 cm3 Ge/Li/ detector connected to a 4096 channel pulse-height analyser. The system resolution was 1.96 keV, peak to Compton ratio 37:1, and the counting efficiency 12.9%, all at the 1.332 MeV photopeak of 60Co. Elements determined: Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Sc, La, Ce, Nd, Sm, Eu, Cd, Tb, Dy, Yb, Ln, Ti, Hg, V, Mn, Fe, Co, Ni, Hg, Al, As, Sb, Se, Cl, Br, I, Th, U

242

Determination of trace elements in Nigerian coal ash by Instrumental Neutron Activation Analysis  

Energy Technology Data Exchange (ETDEWEB)

Instrumental Neutron Activation Analysis (INAA) was used for the determination of the concentration of thirty-three trace elements in both feed-coal and ash obtained from a coal-fired power station in Nigeria. Ash Enrichment Factors (EFs) were determined for each of the elements and the significance of these factors as a measure of environmental contamination assessed. Most of the elements had EFs that were less than 1 while five of the elements (As, Fe, Hf, Na, Ti) had EFs within the range of 1-0. EFs obtained for Mn and U appeared significant.

Ewa, I.O.B.; Adetunji, J.; Elegba, S.B. [Ahmadu Bello University, Zaria (Nigeria). Centre for Energy Research and Training

1996-12-31

243

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

244

Synthesis of hydroxy sodalite from coal fly ash using waste industrial brine solution.  

Science.gov (United States)

The effect of using industrial waste brine solution instead of ultra pure water was investigated during the synthesis of zeolites using three South African coal fly ashes as Si feedstock. The high halide brine was obtained from the retentate effluent of a reverse osmosis mine water treatment plant. Synthesis conditions applied were; ageing of fly ash was at 47 ° C for 48 hours, and while the hydrothermal treatment temperature was set at 140 ° C for 48 hours. The use of brine as a solvent resulted in the formation of hydroxy sodalite zeolite although unconverted mullite and hematite from the fly ash feedstock was also found in the synthesis product. PMID:22175873

Musyoka, Nicholas M; Petrik, Leslie F; Balfour, Gillian; Gitari, Wilson M; Hums, Eric

2011-01-01

245

In situ measurements of the spectral emittance of coal ash deposits  

International Nuclear Information System (INIS)

The spectral emittance of deposits left by bituminous and sub-bituminous coals under oxidizing conditions have been measured in situ. Pulverized coal is injected into a down-fired entrained-flow reactor. Ash accumulates on a probe in the reactor effluent and radiation emitted by the ash layer is recorded using a Fourier transform infrared (FTIR) spectrometer. Values for the spectral emissive power emitted by the ash and the surface temperature of the ash are extracted from these data. These results are then used to calculate the spectral emittance of the deposit. The spectral emittances of ash deposits formed by burning Illinois no. 6 (bituminous) coal and Powder River Basin (sub-bituminous) coal were measured between 3000 and 500 wavenumbers. The spectral emittance of the deposit left by the bituminous coal has a constant value of approximately 0.46 between 3000 and 2400 wavenumbers. Between 2200 and 1200 wavenumbers, the spectral emittance of the deposit increases from approximately 0.47 to approximately 0.61. Between 1200 and 500 wavenumbers, the spectral emittance is relatively constant at 0.61. The spectral emittance of the deposit left by the sub-bituminous coal is also relatively constant between 3000 and 2400 wavenumbers at a value of 0.29. Between 2200 and 500 wavenumbers, the spectral emittance of deposits from the sub-bituminous coal increases from approximately 0.29 to 0.55. Differences between these spectral emittance measurements and those measured ex siance measurements and those measured ex situ illustrate the importance of making in situ measurements. Band emittances were calculated using the measured spectral emittances, and band emittances of the deposits are reported as functions of temperature.

246

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

247

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 rezctor 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 together with an interpretation of their significance in relation to the large scale combustion of these coals as thermal fuels in industrialized countries such as China and Canada. The detailed results showed wide variations in trace impurity concentrations (up to a factor of 100 and more) among the coals studied with few large differences between those of Chinese and Canadian origin except that the rare earths, Sc,Th,U,I, and Se were much higher in the former, other halogens, As and Rb were lower. 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. During static ashing at 750 DegC most of the halogens, S and Se were volatilized whereas most other inorganic constituents were highly retained and concentrated in the ash by factors of 6 to 11. (author)

248

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, Jose; Freire, Valder

2014-01-01

249

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 m(2)/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

250

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

251

Comparison of methods to obtain ash from coal of the Southwest of Colombia  

Science.gov (United States)

The method for concentration of mineral matter at low temperature (about 250 °C), called Low Temperature Ash (LTA) was applied to a sample of coal from the mine "Las Mercedes" located in Colombia southwestern. This method provides better information about the content of mineral matter in natural coal (NC), removing the organic matter more efficiently without significant transformations of mineral phases present in that coal. These results were observed through Mössbauer spectra and X-ray patterns taken from samples of NC, (LTA) and the conventional method of High Temperature Ash (HTA). The results show that the LTA process provides more representative data of the mineral phases for natural coal than that using the conventional HTA process.

Medina, G.; Tabares, J. A.; Alcazar, G. A. Pérez; Barraza, J. M.

2014-01-01

252

Seeding effect on cocomposting wastewater biosolids with coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

The seeding effect on fly ash-amended biosolids composting was evaluated by inoculating a mixture of ash and biosolids with seeding materials before composting. These inocula included thermophilic bacteria (Bacillus. brevis, B. coagulans, and B. licheniformis) isolated from the ash-biosolids compost, a commercial decomposter, and recycled biosolids compost. Although the addition of these microbial additives to the ash-biosolids compost improved the population of thermophilic bacteria at the early stage of composting, the improvement was negligible after 4 days of composting. Inoculation with isolated bacterial culture, milk powder, or the decomposter, only, did not effectively improve the decomposition of organic matter compared with those receiving inoculation of both microbial additives and milk powder together. The isolated Bacillus species was as efficient as the commercial decomposter in accelerating the decomposition rate during ash-amended biosolids composting as indicated by the high amounts of carbon dioxide evolved and cumulative weight loss. Taking into consideration the lower operating cost and acceptable decomposition efficiency, recycled biosolids compost seemed to be a promising additive to ash-amended biosolids compost to improve composting efficiency.

Fang, M.; Wong, J.W.C. [Hong Kong Baptist University, Hong Kong (China). Dept. of Biology

2001-10-01

253

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

254

Desulphurization Characteristic of Industry Alkaline Wastes during Coal Combustion  

Directory of Open Access Journals (Sweden)

Full Text Available The desulphurization characteristics of four sorts of industry alkaline wastes and one sort of limestone were studied by means of flue gas analyzer and the high temperature tube reactor. Pore structure and desulphurization product char-acteristic were investigated respectively by mercury porosimeter and XRD diffraction technology. The reasons why wastes and limestone hold the different desulphurization capability were deeply discussed. The result shows that white clay and carbide slag could capture the release of sulfur at 800-1100?. Salt slurry and red mud could capture the re-lease of sulfur at first stage at 800-900?. But when the experimental temperature rises to 1000?, the sulfur capture abilities of them depress. Pore structures of waste are higher than that of limestone. This makes the sulfation reaction goes further. To sum up, wastes have better sulfur capture ability.

Bin Zheng

2009-03-01

255

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

256

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

257

Progression in sulfur isotopic compositions from coal to fly ash: Examples from single-source combustion in Indiana  

Science.gov (United States)

Sulfur occurs in multiple mineral forms in coals, and its fate in coal combustion is still not well understood. The sulfur isotopic composition of coal from two coal mines in Indiana and fly ash from two power plants that use these coals were studied using geological and geochemical methods. The two coal beds are Middle Pennsylvanian in age; one seam is the low-sulfur ( 5%) Springfield Coal Member of the Petersburg Formation. Both seams have ash contents of approximately 11%. Fly-ash samples were collected at various points in the ash-collection system in the two plants. The results show notable difference in ??34S for sulfur species within and between the low-sulfur and high-sulfur coal. The ??34S values for all sulfur species are exclusively positive in the low-sulfur Danville coal, whereas the ??34S values for sulfate, pyritic, and organic sulfur are both positive and negative in the high-sulfur Springfield coal. Each coal exhibits a distinct pattern of stratigraphic variation in sulfur isotopic composition. Overall, the ??34S for sulfur species values increase up the section in the low-sulfur Danville coal, whereas they show a decrease up the vertical section in the high-sulfur Springfield coal. Based on the evolution of ??34S for sulfur species, it is suggested that there was influence of seawater on peat swamp, with two marine incursions occurring during peat accumulation of the high-sulfur Springfield coal. Therefore, bacterial sulfate reduction played a key role in converting sulfate into hydrogen sulfide, sulfide minerals, and elemental sulfur. The differences in ??34S between sulfate sulfur and pyritic sulfur is very small between individual benches of both coals, implying that some oxidation occurred during deposition or postdeposition. The ??34S values for fly ash from the high-sulfur Springfield coal (averaging 9.7???) are greatly enriched in 34S relative to those in the parent coal (averaging 2.2???). This indicates a fractionation of sulfur isotopes during high-sulfur coal combustion. By contrast, the ??34S values for fly-ash samples from the low-sulfur Danville coal average 10.2???, only slightly enriched in 34S relative to those from the parent coal (average 7.5???). The ??34S values for bulk S determined directly from the fly-ash samples show close correspondence with the ??34S values for SO4- 2 leached from the fly ash in the low-sulfur coal, suggesting that the transition from pyrite to sulfate occurred via high-temperature oxidation during coal combustion. ?? 2007 Elsevier B.V. All rights reserved.

Yaofa, Jiang; Elswick, E.R.; Mastalerz, M.

2008-01-01

258

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

259

USE OF COAL FLY ASH AS A CATALYST IN THE PRODUCTION OF BIODIESEL  

Directory of Open Access Journals (Sweden)

Full Text Available South Africa is largely dependent on the combustion of coal for electricity production; Eskom’s coalfiredpower stations consume approximately 109 million tons of coal per annum, producing around 25million tons of ash, to supply the bulk (93% of South Africa’s electricity. The management of this flyash has been a concern with various approaches for its beneficial use being investigated. This workpresents the results of transesterification reaction using sunflower oil as feedstock with methanol andclass F fly ash catalyst derived from a coal fly ash dump in South Africa to produce methyl esters (biodiesel.The fly ash based catalyst was prepared using the wet impregnation procedure with different loadingsof potassium. This was characterized by powder X-ray diffraction (XRD, FTIR spectroscopy. The XRDpatterns obtained indicated that the structure of the support gradually deformed with an increase inthe loading and the extent of decomposition of KNO3 varied with the amount of loading. The influenceof various reactions parameters such as loading amount of active components, methanol: oil ratio, reactiontime, temperature and catalyst deactivation was investigated. The fly ash based catalyst loaded with5% wt KNO3 at a reaction temperature of 160ºC exhibited maximum oil conversion (86.13%. Thebiodiesel synthesized was tested and important fuel properties of the methyl esters (Biodiesel comparedwell with ASTM biodiesel standard.

Farouk Ameer

2010-12-01

260

Evaluation of ash content in coals of Chelyabinsk basin by well logging  

International Nuclear Information System (INIS)

Based on a comparison of data from carbon assays on cores with data from logging measurements (resistivity logging, gamma-gamma logging-II, thermal logging), correlations of each geophysical parameter with the coal ash were obtained. To exclude the effect of borehole and other conditions of measurement, ratios of average values of the parameters in the interval of the coal stratum studied to the average value of the parameter for a reference coal stratum in the same borehole with known and established ash were used rather than absolute values. A dependence of the values of the 20 resistivity logging parameters on depth was noted. The most marked correlation, between the relative geophysical parameters and the ash, was establihsed for the zone 150 to 700 m deep. Graphs were prepared, and are presented, for determining the ash in this zone. The most reliable ash determination is guaranteed when a group of parameters and calculation of the average data for each of them are used. For calculating the precision, the results obtained for 55 intersecting strata were compared with data from penetration of a core in rock workings. Absolute average arithmetical divergences for the resistivity, thermal, gamma-gamma-II, and gamma-gamma-S logging methods were 3.0-5.3%, and for different groups of parameters, 2.0-3.4%

 
 
 
 
261

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

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english 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.

262

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

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english 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

263

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

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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 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 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.

Ochieng Aoyi

2010-09-01

264

Coal ash as a source of radioactivity in the environment at Svilajnac in 1998  

International Nuclear Information System (INIS)

Coal ash was dumped in an area in central Serbia near to Svilajnac. The continual monitoring of coal, ash, water from the waste dump, surface water, agricultural and non-agricultural soils, and vegetation used as a source of human and animal food, for activities of the natural radionuclides 40K, 235U, 238U, 226Ra, 214Bi, 232Th, 234Th, 7Be, 208Tl and 137Cs, and 134Cs, provided evidence of increased levels of radioactivity in this region due to coal ash. Samples in the form of ash, water, soil and vegetation were analyzed by means of gamma spectrometry (employing germanium detectors manufactured by ORTEC, with a relative efficiency of 25% and a resolution of 1.85 KeV, coupled up to a multi-channel analyzer with 8192 channels). As could be determined in our investigations, the main source of activity is natural 40K (in all samples including water, but due to different concentrations at the source, the measured activity is also different). Significant activity concentration values were yielded by 238U, 226Ra, and 214Bi, with different amounts in total activity being determined in different samples. Also discussed in this paper are some useful applications of the coal combustion by-products (CCBs) which otherwise rapidly accumulate and cause enormous problems in the environment. (orig.)

265

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

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Full Text Available The fines of sub-bituminous coals from the Cíge? and the Handlová Collieries in use as steam coal in coal-fired power plant weresubjected 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°-75°-20° was applied. Vortex finder (overflowand 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 resultedin the obtaining of significantly deashed 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 Cíge? Colliery. Similarly, in the case of coal from the Handlová Colliery andits 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 % total sulphur rejection.

Štefan Jakabský

2010-11-01

266

Elemental particle size distribution in coal fly ash determined by PIXE analysis of thick samples  

Science.gov (United States)

The elemental particle size distribution in coal fly ash, collected for use in biological tests, has been determined by PIXE analysis of thick samples. The flue gas particles were sampled from the stack of a power plant with a dilution and cooling probe. Elements found to be enriched in small particles were also found to be enriched in the material collected with the probe when compared with the material collected from the electrostatic precipitator of the power plant. This behaviour verifies the assumption that volatile elements are condensed onto the surface of the fly ash particles in the flue gas during cooling. Size distribution, density and specific surface area of the collected material were also measured. Thick samples were prepared by mixing of particulate matter with cellulose powder or polyvinylalcohol which were then pressed into pellets. The accuracy of the sample preparation and the analytical technique was verified in the analysis of a standard coal fly ash, NBS SRM 1633a.

Ahlberg, Mats S.; Fängmark, Ingrid; Carlsson, Lars-Eric

1984-04-01

267

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)

268

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

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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

269

Influence of several experimental parameters on As and Se leaching from coal fly ash samples  

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Coal fly ash leaching process for As and Se is studied. Environmental parameters such as pH, temperature, solid-liquid ratio, particle size and leaching time are taken into account in order to simulate As and Se leaching process for disposal coal fly ash. Analysis of reference materials was carried out by using of hydride generation coupled to atomic fluorescence spectrometry. Plackett-Burman experimental design is used to know the significative parameters, and Box-Behnken experimental design is used to refine the results obtained for these significative parameters. pH and temperature shown a hardly influence in leaching process. Furthermore, leaching time was also significative. According our results, it may be assumed that percentage of As and Se leaching in experimental conditions tested is relatively low for acidic fly ashes.

Otero-Rey, Jose R. [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain); Mato-Fernandez, Maria J. [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain); Moreda-Pineiro, Jorge [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain); Alonso-Rodriguez, Elia [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain)]. E-mail: elia@udc.es; Muniategui-Lorenzo, Soledad [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain); Lopez-Mahia, Purificacion [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain); Prada-Rodriguez, Dario [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain)

2005-02-28

270

Influence of several experimental parameters on As and Se leaching from coal fly ash samples  

International Nuclear Information System (INIS)

Coal fly ash leaching process for As and Se is studied. Environmental parameters such as pH, temperature, solid-liquid ratio, particle size and leaching time are taken into account in order to simulate As and Se leaching process for disposal coal fly ash. Analysis of reference materials was carried out by using of hydride generation coupled to atomic fluorescence spectrometry. Plackett-Burman experimental design is used to know the significative parameters, and Box-Behnken experimental design is used to refine the results obtained for these significative parameters. pH and temperature shown a hardly influence in leaching process. Furthermore, leaching time was also significative. According our results, it may be assumed that percentage of As and Se leaching in experimental conditions tested is relatively low for acidic fly ashes

271

The use of tetragnathid spiders as bioindicators of metal exposure at a coal ash spill site.  

Science.gov (United States)

On 22 December 2008, a dike containing coal fly ash from the Tennessee Valley Authority Kingston Fossil Fuel Plant (TN, USA) failed, resulting in the largest coal ash spill in US history. The present study was designed to determine sediment metal concentrations at multiple site locations and to determine whether site-specific bioaccumulation of metals existed in tetragnathid spiders. Selenium and nickel were the only 2 metals to exceed the US Environmental Protection Agency sediment screening levels. Selenium concentrations in spiders were significantly higher at ash-affected sites than in those from reference sites. The ratio of methylmercury to total mercury in spiders was found to be similar to that in other organisms (65-75%), which highlights the potential use of tetragnathid spiders as an indicator species for tracing contaminant transfer between the aquatic and terrestrial ecosystems. PMID:23686551

Otter, Ryan R; Hayden, Mary; Mathews, Teresa; Fortner, Allison; Bailey, Frank C

2013-09-01

272

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

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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

273

Hydrothermal synthesis of belite cement from coal fly ashes with various CaO content  

International Nuclear Information System (INIS)

This paper summarizes the results of hydrothermal synthesizing belite cement from reactive mixtures consisting of two waste kinds (bottom ash and fly ash) from fluidized brown coal combustion in Slovakian power plant and CaO (analytical grade reagent) addition with CaO/SiO2 molar ratio of 2 in rotating autoclave under various conditions (175 a 200 grad C; 2 and 4 hours; water and 0.2 and 0.5 % NaOH solution). Changes in structure and phase composition of hydrothermally synthesized belite precursors and subsequent calcinated products were compared with those of starting mixtures. Based on XRD diffraction patterns and infrared spectra of pre-treatment products, the formation of the new profiles corresponding to CSH and ?-C2SH phases with low degree of ordering as belite precursors after hydrothermal treatment was confirmed. Optimal conditions of hydrothermal treatment of reactive mixtures were 200 grad C and 4 hours in water. Different phase composition of products before and after calcination depends upon waste quality and precursor's synthesis conditions. Optimal calcination temperature in term of product quality to belite in precursors prepared by hydrothermal treatment of reactive mixture based on fly ash is 800 grad C because gehlenite as cement hydration retarder isn't formed at this temperature. Evaluation of phase composition in hydrothermally treated products of reactive mixtures showed that bottom ash with high CaO content fixed in anhyd ash with high CaO content fixed in anhydrite form (44.1 %) as a very stable compound is not suitable as raw material for synthesizing belite phase whereas coal fly ash with low CaO content in anhydrite form (4.2 %) and its hydrothermal treatment in combination with subsequent heating offer opportunities for the utilization of coal fly ash as raw material for belite production. (authors)

274

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

275

Coal fly ash utilization: Low temperature sintering of wall tiles  

International Nuclear Information System (INIS)

We present here a study of the sintering of fly ash and its mixture with low alkali pyrophyllite in the presence of sodium hexa meta phosphate (SHMP), a complex activator of sintering, for the purpose of wall tile manufacturing. The sintering of fly ash with SHMP in the temperature range 925-1050 deg. C produces tiles with low impact strength; however, the incremental addition of low alkali pyrophyllite improves impact strength. The impact strength of composites with ?40% (w/w) pyrophyllite in the fly ash-pyrophyllite mix satisfies the acceptable limit (19.6 J/m) set by the Indian Standards Institute for wall tiles. Increasing the pyrophyllite content results in an increase in the apparent density of tiles, while shrinkage and water absorption decrease. The strength of fly ash tiles is attributed to the formation of a silicophosphate phase; in pyrophyllite rich tiles, it is attributed to the formation of a tridymite-structured T-AlPO4 phase. Scanning electron micrographs show that the reinforcing rod shaped T-AlPO4 crystals become more prominent as the pyrophyllite content increases in the sintered tiles

276

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 o...

Abdulhameed Umar Abubakar; Khairul Salleh Baharudin

2012-01-01

277

Impact of fly ash from coal-fired power stations in Delhi, with particular reference to metal contamination  

International Nuclear Information System (INIS)

Indraprastha Power Station (IPP station) and Rajghat Power House (RHP) are both coal-fired power stations in New Delhi. Ash content of the coal used ranges between 38-47%. The ash is collected in electrostatic precipitators which have an efficiency of 99.3% (IPP station), and 99.7% (RPH). There are instances of major dust pollution around the power stations from fly ash dispersal. The main method of disposal of fly ash from the power stations is by mixing with water; the resultant slurry is pumped through pipes to ash disposal ponds. The supernatant from these ponds is discharged into the River Yamuna. Field studies have revealed large quantities of fly ash being deposited into the river. Field studies, conducted in January 1995 investigated the impact of fly ash dispersal in the Delhi region with particular reference to metal contamination

278

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 ...

279

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

Energy Technology Data Exchange (ETDEWEB)

Highlights: Black-Right-Pointing-Pointer Coal washing wastewater was analyzed. Black-Right-Pointing-Pointer Several fly ash-based composite coagulants were prepared to treat coal washing wastewater. Black-Right-Pointing-Pointer 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 Al{sup 3+} and Fe{sup 2+}/Fe{sup 3+} 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{sup -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 Al{sup 3+} and Fe{sup 3+} and introduced Ca{sup 2+} 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 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.

Yan, Long, E-mail: ylyanlong@126.com [School of Chemistry and Chemical Engineering, Yulin University, Yulin, 719000 (China); Institute of Energy Chemistry, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi' an, 710062 (China); Key Laboratory of Applied Surface and Colloid Chemistry, Shaanxi Normal University, Ministry of Education, Xi' an, 710062 (China); Wang, Yufei [School of Chemistry and Chemical Engineering, Yulin University, Yulin, 719000 (China); Ma, Hongzhu, E-mail: hzmachem@snnu.edu.cn [Institute of Energy Chemistry, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi' an, 710062 (China); Key Laboratory of Applied Surface and Colloid Chemistry, Shaanxi Normal University, Ministry of Education, Xi' an, 710062 (China); Han, Zhiping; Zhang, Qiang [School of Chemistry and Chemical Engineering, Yulin University, Yulin, 719000 (China); Chen, Yashao [Institute of Energy Chemistry, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi' an, 710062 (China); Key Laboratory of Applied Surface and Colloid Chemistry, Shaanxi Normal University, Ministry of Education, Xi' an, 710062 (China)

2012-02-15

280

Thermal analysis of fly ashes sourced from European non-blended coals  

Energy Technology Data Exchange (ETDEWEB)

Fly ashes exist as a mixture of major amorphous phases and minor crystalline phases. For commercial applications, such as in concretes and for the production of zeolites, it would be desirable to be able to predict the reactivity of fly ashes. The amorphous phase dominates degradation behaviour, because glasses have a higher potential energy than the equivalent crystal structure and the variation of bond angles and distances in a glass make the bond breakage easier. Despite the large quantities of fly ash produced annually by coal-burning power plants, there have been very few studies investigating the microstructure and composition of the amorphous component. In particular, there has been little research undertaken in measuring the glass transition temperature (T{sub g}), which can be directly correlated to the chemical reactivity of the glass phase. Thirteen European fly ashes were used for the present study. Differential scanning calorimetry (DSC) was employed to determine the presence of transition temperatures and any other thermal events (exotherms or endotherms) in the glassy phase of the fly ashes. Several different but distinct behaviours were evident in the DSC traces with T{sub g} values visible for six of the ashes. The results suggest that thermal analysis has potential as a technique for fly ash characterisation.

Stanton, K.T.; Towler, M.R.; Mooney, P.; Hill, R.G.; Querol, X. [University of Limerick, Limerick (Ireland). Dept. of Material Science & Technology, National Technology Park

2002-07-01

 
 
 
 
281

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

282

The Effect of Microwave Energy on Grindability of a Turkish High-Ash Coal  

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In the present study, the effect of microwave energy on grindability of high-ash (46.39% and sulphur (3.99% Turkish coal has been investigated. Coal samples (-9.52+3.18 mm was treated by microwave at a frequency of 2.45 GHz with different power levels (0.48-0.64-0.80 kW and residence times (30-150 s.. In order to determine the crushing/grinding resistance of low ranked lignite coal samples treated by microwave oven, the Impact Strength Index (ISI test was applied for each treated and untreated sample and compared with each other. Experimental results have shown that significant increases in grindability were achieved when the coal samples were exposed to microwave radiation. The ISI of samples decreased up to 96%.

Key words: Microwave energy; Low rank coal; Crushability; Grindability; Impact strength ?ndex (ISI

O. Y. Toraman

2012-06-01

283

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

284

Surface tension measurements of coal ash slags under reducing conditions at elevated pressures  

Energy Technology Data Exchange (ETDEWEB)

The aim of limiting the amount of CO{sub 2} that is released together with other exhaust gases from power plants can be reached by technologies allowing for a systematic separation of this greenhouse gas. One such technology is the integrated gasification combined cycle power plant which makes use of a coal gasification step. For the gasification involving temperatures far higher than in typical pulverised combustion chambers, ash contained in the fuel is liquefied (slag) and must be removed from the cycle to guarantee safe operation of downstream equipment. To keep the efficiency of the power plant as high as possible, hot gas cleaning facilities are most desirable for this purpose. The design of these installations necessitates knowledge about thermophysical properties of coal ash slags, especially in reducing, pressurised atmospheres. In this work, the surface tension of 15 coal ash slags was measured in argon hydrogen gas of up to 10 bar absolute pressure according to the sessile drop method. Compared to experiments at 1 bar, surface tension values up to 42% lower were found on applying pressure. Additionally, shifts in the melting temperature interval of the ashes due to increased pressure were observed. The surface tension values obtained in pressurised atmospheres ranged from 270 to 490 mN/m with respect to temperature intervals where almost no data scattering occured. 43 refs., 11 figs., 1 tab.

Tobias Melchior; Marc Blaesing; Guenther Puetz; Michael Mueller [Forschungszentrum Juelich GmbH, Juelich (Germany). Institute of Energy Research

2011-01-15

285

Catalytic oxidation of gaseous reduced sulfur compounds using coal fly ash.  

Science.gov (United States)

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 H(2)S and ethanethiol, but not dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) at room temperature. In batch reactor systems, initial concentrations of 100-500 ppmv H(2)S 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 H(2)S and ethanethiol for the room temperature reactions (23-25 degrees C). Additionally, in a continuous flow packed bed reactor, a gaseous stream containing an inlet H(2)S concentration of 400-500 ppmv was reduced to 200 ppmv at a 4.6s residence time. The removal efficiency remained at 50% for approximately 4.6h or 3500 reactor volumes. These results demonstrate the potential of using coal fly ash in reactors for removal of H(2)S and other reduced sulfur compounds. PMID:12409240

Kastner, James R; Das, K C; Melear, Nathan D

2002-11-11

286

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.)

287

Physico-chemical characteristics of European pulverized coal combustion fly ashes  

Energy Technology Data Exchange (ETDEWEB)

Fly ashes sourced from European pulverised coal burning power plants (from Spain, The Netherlands, Italy and Greece) were characterised in terms of their chemical composition, mineralogy and physical properties. The amount and composition of the glass present in the ashes were also determined. The materials analysed have very different compositions and were selected with a view to determining their suitability for different applications and for further studies on applications. The results were compared to the literature to determine their similarities to UK coal fly ashes. Chemical analysis has enabled the categorisation of the ashes based on their oxide contents. Devitrification of the glass phase has been effected using suitable heat treatments and crystal phases formed are used as an indicator of glass reactivity. Based on leaching tests, certain ashes were identified as having limitations for some further uses due to the relatively high levels of leachable trace elements. A wide range of physical properties such as density were observed and these are related to factors such as mineralogical content and particle morphology. 34 refs., 3 figs., 8 tabs.

N. Moreno; X. Querol; J.M. Andres; K. Stanton; M. Towler; H. Nugteren; M. Janssen-Jurkovicova; R. Jones [Institute of Earth Sciences ' Jaume Almera' , Barcelona (Spain)

2005-08-01

288

Adsorption of Iron by Fly Ash Adsorbent of Coal  

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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

289

Determination of the kinetic models and associated parameters for the low temperature combustion and gasification of high-ash coal chars / Delani Njapha  

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South Africa has large coal reserves and the power generation industry produces approximately 95% of the electricity from coal. Most of the high-grade coal is exported leaving behind a discard of high ash coal. For the power generation industry to sustain itself, some means of processing the high ash coal should be implemented. A fluidised bed gasification process is seen as the best alternative to conventional pulverised coal combustion process since it can handle a wide varie...

Njapha, Delani

2003-01-01

290

Soil improvement with coal ash and sewage sludge: a field experiment  

Science.gov (United States)

A field experimental study was carried out successfully to improve the quality of the sandy soil by adding coal ash and sewage sludge. One ha of barren sandy soil field was chosen for the experiment in Shanghe County, Shandong Province, China. For soil amelioration and tree planting, two formulas of the mixture:coal ash, sewage sludge and soil, in ratios of 20:10:70 and 20:20:60, respectively, were used. Poplar trees were planted in pits filled with soils with additives (mixture of ash and sludge) as well as in the original sandy soil. In the 19th months after the trees were planted, the soils with additives were sampled and analyzed. The results show that the barren sandy soil was greatly improved after mixing with coal ash and sludge. The improved soils have remarkably higher nutrient concentrations, better texture, smaller bulk density, higher porosity and mass moisture content, and higher content of fine-grained minerals. During the first 22 months after planting, the annual increase in height of the trees grown in the soil with additives (4.78 m per year) was 55% higher than that of the control group (3.07 m per year), and the annual increase in diameter at the breast height (1.3 m) was 33 % higher (43.03 vs. 32.36 mm). Trees planted in soils with additives appeared healthier and shed leaves later than those in the control group. As the volume of the additives (30-40% in both formulas) is less than that of the sandy soil in and around the tree pits, it appears that the use of coal ash and sludge for tree planting and soil amelioration is environmentally safe even though the additives have relatively high heavy metal concentrations.

Shen, Junfeng; Zhou, Xuewu; Sun, Daisheng; Fang, Jianguo; Liu, Zhijun; Li, Zhongmin

2008-02-01

291

The occurrence of gold in fly ash derived from high-Ge coal  

Science.gov (United States)

We present the first data on the mode of occurrence of Au in fly ashes from the Wulantuga and Lincang power plants in China, which burn high-Ge coal. Gold occurs as fine-grained drop-like particles with a size of n*0.01-0.2 ?m on the surface of the glass globules. These features of the Au particles are proof for Au condensation from the gas phase and deposition on the surface of fly ash in the cooler zone of the electrostatic precipitator and baghouse filter.

Seredin, Vladimir V.; Dai, Shifeng

2014-01-01

292

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

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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

293

Nitric Oxide Removal From Flue Gases By Carbon-enriched Coal Fly Ash  

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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-activate...

Begoña Rubio; Maria Teresa Izquierdo

2013-01-01

294

Mutagenicity of coal fly ash: a new bioassay for mutagenic potential in a particle feeding ciliate  

Energy Technology Data Exchange (ETDEWEB)

The use of the established mutagenesis assay in Paramecium as a prescreen for hazardous environmental particles is described. Since these protozoans ingest particles of the size respired by animals and man, the biological effects of the respirable fraction of fly ash particles were monitored in particle-feeding eukaryotic cells. Fly ash from coal combustion was utilized for these studies and was found to be mutagenic. The effects of physical and chemical treatment of the particle mutagenicity provided evidence for both heat-stable, heat-labile and acid extractable mutagenic agents.

Smith-Sonneborn, J. (Univ. of Wyoming, Laramie); Fisher, G.L.; Palizzi, R.A.; Herr, C.

1981-01-01

295

Reclamation of spoil and refuse material produced by coal mining using bottom ash and lime  

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Brazil's coal production is about five million tonnes per year, mostly by surface mining operations. Mined land reclamation is difficult due to the high acidity generated by the sulphur compounds' oxidation. In order to evaluate the feasibility of using bottom ash and lime for land reclamation of coal mining and processing refuse deposit areas, a field experiment was carried out in a coal waste dumping area over 20 m deep, located on the Butia County Recreio mine, in Rio Grande do Sul state, Brazil in 1992 and 1993. Trenches were dug in the coal refuse and filled with bottom ash covered with a layer of soil of different depths. Several summer and winter plant species were grown. A minimum of 0.1 m soil layer over 0.2 m bottom ash with proper liming and fertilization was required to promote plant growth. Heavy metals Cr, Cd, Ni and Pb concentrations in the plants' shoot were in the range usually determined for plants grown on uncontaminated soils.

Tedesco, M.J.; Teixeira, E.C.; Medina, C.; Bugin, A. [Fundacao Estadual Protecao Ambiental, Porto Alegre (Brazil)

1999-05-01

296

Solidification of coal ash by new hydro thermal reaction. Sound-absorber, external wall, and artificial crushed stone formed from coal ash; Atarashii suinetsu kokaho niyoru sekitanbai no koka. Sekitanbai wo taryo ni riyoshita kyuonzai gaihekizai jinko saiseki  

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A sound-absorber, an external wall and artificial crushed stone were developed as construction materials fully utilizing coal ash. The materials are made by mixing coal ash with Ca constituents and water, cured in an autoclave after pre-curing, and then solidified. This method can have Si constituents in coal ash react efficiently. Pre-curing under an optimal condition produces calcium silicate hydrate, and steam curing produces `tobermorite` crystals which contribute to improving the mechanical strength. Coal ash has such advantages that it has high utilization rate regardless of kinds of coal ash, high-strength solids can be obtained, and the number of curing days is reduced. Mixing in a foaming agent during the mixing process results in a sound absorber, which ensures about the same sound absorbability of about 90% (at 500 Hz) as conventional sound absorbers at a coal utilization rate of 70%. The external wall material formed by vacuum extrusion has the same compression and bending strength as extruded cement slabs, at a coal ssh utilization as high as 80%. The artificial crushed stone obtained by crushing the material after solidification utilizes the coal at a rate of 90%, and meets the JIS crushed stone standard. 4 figs.

Niimi, Y. [Chubu Electric Power Co. Inc., Nagoya (Japan)

1996-07-01

297

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

298

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

299

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

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Highlights: Black-Right-Pointing-Pointer The indirect CO{sub 2} mineralization by brown coal fly ash has been tested. Black-Right-Pointing-Pointer A large CO{sub 2} capture capacity of fly ash under mild conditions was achieved. Black-Right-Pointing-Pointer The kinetic analysis confirmed a fast reaction rate with low activation energy. Black-Right-Pointing-Pointer 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 CO{sub 2} 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 CO{sub 2} capture capacity of fly ash under mild conditions has been confirmed. The CO{sub 2} was fixed in both carbonate precipitates and water-soluble bicarbonate, and the conversion between these two species was achievable at approximately 60 Degree-Sign C and a CO{sub 2} 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/piperazine system. The CO{sub 2} capture capacity of this system has also proven to reach maximum 264 kg CO{sub 2}/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.

Sun, Yong; Parikh, Vinay [Department of Chemical Engineering, Monash University, Wellington Road, Clayton, GPO Box 36, Victoria 3800 (Australia); Zhang, Lian, E-mail: lian.zhang@monash.edu [Department of Chemical Engineering, Monash University, Wellington Road, Clayton, GPO Box 36, Victoria 3800 (Australia)

2012-03-30

300

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

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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

 
 
 
 
301

Controlled low-strength materials containing mixtures of coal ash and new pozzolanic material  

Energy Technology Data Exchange (ETDEWEB)

A significant amount of ash is generated from burning wood with supplementary fuels such as coal, oil, natural gas, and coke by pulp and paper mills, and wood products manufacturers. Thus, the ash generated from such facilities is a mixture of wood ash and other ashes generated from the aforementioned supplemental fuels. In this investigation, such wood ash is referred to as a combined-fuel ash (CFA). This investigation was carried out to develop controlled low-strength material (CLSM), mixtures using various sources of CFAs. Three different series of CLSM mixtures were manufactured using five sources of CFAs. Each series of CLSM mixtures was designed for a different long-term compressive strength: {lt} 0.7 MPa ({lt}100 psi), 0.7 to 3.4 MPa (100 to 500 psi), and 3.4 to 8.3 MPa (500 to 1200 psi). All CLSM mixtures were tested for flow, bleedwater, settlement, shrinkage and cracking, setting characteristics, density, compressive strength, and permeability. The results revealed that CLSM, meeting ACI 229R requirements, can be manufactured using substantial amounts of CFAs.

Naik, T.R.; Kraus, R.N.; Siddique, R. [University of Wisconsin, Milwaukee, WI (USA). Dept. of Civil Engineering and Mechanics

2003-06-01

302

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)

303

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

International Nuclear Information System (INIS)

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 133Ba 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 133Ba source is determined to be 85 mm source to detector spacing, and 50 mm iron thickness shielding. This configuration gives the best results for ash prediction, where the rms deviation for ash is 1.47%

304

Characterization of unburned carbon from ash after bituminous coal and lignite combustion in CFBs  

Energy Technology Data Exchange (ETDEWEB)

This paper deals with the characterisation of carbon (UC) from bottom ash (BA) and fly ash (FA) samples from two fluidised-bed power stations burning bituminous coal and lignite. The laboratory results for the carbon determinations and its mass balances are evaluated. Chemical and mineral analyses and textural characteristics (specific surface area and pore-size distribution) are presented. Depletion/enrichment of selected elements (S, Cl, V, Cr, Ni, Cu, Zn, As, Se, Sb, Hg, and Pb) in carbon from the bottom ash are compared with both ash compostions. The strong positive relationships between the concentrations of some trace element contents (Hg, Se, As, Cu, Ni, V and Cl) in fly ash with the content of carbon and the specific surface area of FA are presented and expressed by regression equations with very high correlation coefficients. Laser ablation-ICP-MS has been used to obtain an insight into element distributions within carbon grains from the bottom ash. 26 refs., 7 figs., 6 tabs.

L. Bartonova; Z. Klika; D.A. Spears [VSB-Technical University of Ostrava, Ostrava-Poruba (Czech Republic). Department of Analytical Chemistry and Material Testing

2007-02-15

305

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

International Nuclear Information System (INIS)

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 133Ba 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 133Ba source is determined to be 85 mm source to detector spacing, and 50 mm iron thickness shielding. This configuration gives the best results for ash prediction, where the rms deviation for ash is 1.47%

306

Neutron-gamma logging for iron in coal and implications for estimating the ash fusion characteristics at Callide Mine  

International Nuclear Information System (INIS)

The neutron-gamma technique was used to determine iron (Fe2O3) concentration of coal in seams having highly variable iron content. The measurements were carried out in water-filled, cored boreholes with a nominal diameter of 96 mm. The logging was 1 m/min. The logging probe contained a 1.6 ?g 152Cf neutron source and a 51 x 51 mm BGO detector. The work established the existence of a relationship between the iron content of the ash and the slagging index of coal at the Callide Mine. Based on this relationship it is possible to determine ash fusion properties indirectly by the measurement of iron content of the ash in coal seams by the neutron-gamma technique. The coal ash content is determined simultaneously. (author)

307

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

308

Impacts of pH and ammonia on the leaching of Cu(II) and Cd(II) from coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

Many coal-fired power plants are implementing ammonia-based technologies to reduce NOx, emissions. Excess ammonia in the flue gas often deposits on the coal fly ash. Ammonia can form complexes with many heavy metals and change the leaching characteristics of these metals. This research tends to develop a fundamental understanding of the ammonia impact on the leaching of some heavy metals, exemplified by Cu(II) and Cd(II), under different pH conditions. Batch results indicated that the adsorption is the main mechanism controlling Cu(II) and Cd(II) leaching, and high concentrations of ammonia ({gt} 5000 mg/l) can increase the release of Cu(II) and Cd(II) in the alkaline pH range. Based on the chemical reactions among fly ash, ammonia, and heavy metal ion, a mathematical model was developed to quantify effects of pH and ammonia on metal adsorption. The adsorption constants (log K) of Cu{sup 2+}, Cu(OH){sup +}, Cu(OH){sub 2}, and Cu(NH{sub 3}){sub m}{sup 2+} for the fly ash under investigation were respectively 6.0, 7.7, 9.6, and 2.9. For Cd(II), these constants were respectively 4.3, 6.9, 8.8, and 2.6. Metal speciation calculations indicated that the formation of less adsorbable metal-ammonia complexes decreased metal adsorption, therefore enhanced metal leaching.

Wang, J.M.; Ban, H.; Teng, X.J.; Wang, H.; Ladwig, K. [University of Missouri, Rolla, MO (United States). Dept. of Civil Architectural & Environmental Engineering

2006-09-15

309

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

Directory of Open Access Journals (Sweden)

Full Text Available 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 sulfur self-retention are coal rank, content of sulfur forms, molar Ca/S ratio and particle radius. A comparison with the experimentally obtained values in a FB reactor showed that the model can adequately predict the kinetics of the process, the levels of the obtained values of the SSR efficiencies, as well as the influence of temperature and coal particle size.

BRANIMIR JOVANCICEVIC

2003-03-01

310

ADSORPTION OF REACTIVE BLACK 5 FROM AQUEOUS SOLUTION BY ZEOLITE FROM COAL FLY ASH: EQUILIBRIUM AND KINETIC STUDIES  

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Zeolite synthesized from coal fly ash (ZC) and coal fly ashes (CC) were used as adsorbents to removeReactive Black 5 (RP5) dye from aqueous solutions. The equilibrium time was reached after 420 min. Thekinetics studies indicated that the adsorption followed the pseudo-second order kinetic and that surfaceadsorption and intraparticle diffusion were involved in the adsorption mechanism. The isotherm adsorption datafit accordingly to the Langmuir model for both adsorbents. The maximum adsorption...

Cunico, Patricia Fungaro

2011-01-01

311

3-E analysis of advanced power plants based on high ash coal  

Energy Technology Data Exchange (ETDEWEB)

The objective of the study is to identify the 'best' possible power plant configuration based on 3-E (namely energy, exergy, and environmental) analysis of coal-based thermal power plants involving conventional (subcritical (SubC)) and advanced steam parameters (supercritical (SupC) and ultrasupercritical (USC)) in Indian climatic conditions using high ash (HA) coal. The analysis is made for unit configurations of three power plants, specifically, an operating SubC steam power plant, a SupC steam power plant, and the AD700 (advanced 700 degrees C) power plant involving USC steam conditions. In particular, the effect of HA Indian coal and low ash (LA) reference coal on the performance of these power plants is studied. The environmental impact of the power plants is estimated in terms of specific emissions of CO{sub 2}, SOx, NOx, and particulates. From the study, it is concluded that the maximum possible plant energy efficiency under the Indian climatic conditions using HA Indian coal is about 42.3% with USC steam conditions. The results disclose that the major energy loss is associated with the heat rejection in the cooling water, whereas the maximum exergy destruction takes place in the combustor. Further, the sliding pressure control technique of load following results in higher plant energy and exergy efficiencies compared to throttle control in part-load operation.

Suresh, M.V.J.J.; Reddy, K.S.; Kolar, A.K. [Indian Institute of Technology, Madras (India)

2010-06-25

312

Zinc estimates in ore and slag samples and analysis of ash in coal samples  

International Nuclear Information System (INIS)

Zinc estimates in ore and slag samples were made using the radioisotope X-ray fluorescence method. A 10 mCi 238Pu was employed as the primary source of radiation and a thin crystal NaI(Ti) spectrometer was used to accomplish the detection of the 8.64 keV Zinc K-characteristic X-ray line. The results are reported. Ash content of coal concerning about 100 samples from Ravindra Khani VI and VII mines in Andhra Pradesh were measured using X-ray backscattering method with compensation for varying concentrations of iron in different coal samples through iron-X-ray fluorescent intensity measurements. The ash percent is found to range from 10 to 40. (author)

313

Adsorption of Cu{sup 2+} from water using raw and modified coal fly ashes  

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In this study, we found that both raw and modified coal fly ashes effectively adsorb Cu{sup 2+} from wastewater. The adsorption capacities followed the order CFA {gt} CFA-600 {gt} CFA-NaOH. The adsorption isotherms for Cu{sup 2+} on the raw and modified coal fly ashes fit the Langmuir, Freundlich, and DKR isotherms quite well. These adsorptions were endothermic in nature; the values of E (between 1.3 and 9.6 kJ mol{sup -1}) were consistent with an ion-exchange adsorption mechanism. The adsorptions of Cu{sup 2+} onto CFA, CFA-600, and CFA-NaOH followed pseudo-second-order kinetics. 29 refs., 4 figs., 4 tabs.

Ting-Chu Hsu; Chung-Chin Yu; Chin-Ming Yeh [Vanung University, Taiwan (China). Department of Environmental Engineering

2008-06-15

314

Zeolite synthesis from coal bottom ash for recycling as an absorbent of heavy metals  

Energy Technology Data Exchange (ETDEWEB)

This study focused on the synthesis of zeolite from coal bottom ash and the cation exchange capacity (CEC) assessment of synthesized products. To that end, zeolificaion tests were carried out at four temperature levels (80, 100, 120, 150{sup o}C) and five NaOH concentration levels (1, 2, 3, 4, 5M) by the alkali hydrothermal method. Consequently, NaP1, hydroxy-sodalite, and tobermorite were produced from coal bottom ash. NaP1 with an excellent cation exchange capability had a high crystallinity at below 2M NaOH and 120{sup o}C; and the maximum CEC value was 160meq/100g at 2M NaOH and 120{sup o}C under the given conditions.

Ahn, Ji-Whan; Han, Gi-Chun; You, Kwang-Suk; Um, Nam-Il; Cho, Hee-Chan

2006-07-01

315

Composition, morphology, properties of coal fly ash microspheres and their application for conditioning liquid radioactive waste  

Energy Technology Data Exchange (ETDEWEB)

Using methods of the Moessbauer spectroscopy, scanning electron microscopy, and thermodynamic analysis of phase formation in silicate multi-component melts, the detailed study of composition, morphology, and properties of fly ash microspheres resulting from combustion of three coals (Irsha-Borodinskii, Kuznetskii and Ekibastuzskii) was carried out. About 60 microspherical products with an iron content of 2-94 wt.% Fe{sub 2}O{sub 3} were obtained. The ranges of microsphere composition, suitable for liquid radioactive waste solidification in the forms of iron phosphate (36-94 wt.% Fe{sub 2}O{sub 3}) and aluminosilicate (2-20 wt.% Fe{sub 2}O{sub 3}) ceramics were determined. The possibility of producing porous materials and specific microspherical sorbents, based on coal fly ash cenospheres and their application for mobilisation of liquid radioactive waste solidification was demonstrated. (author)

Anshits, N.N. [Institute of Chemistry and Chemical Technology, SB RAS (ICCT SB RAS), Krasnoyarsk (Russian Federation)]. E-mail: anshits@icct.ru; Salanov, A.N.; Vereshchagina, T.A.; Kruchek, D.M.; Bajukov, O.A.; Tretyakov, A.A.; Revenko, Yu.A.; Anshits, A.G

2006-07-01

316

Composition, morphology, properties of coal fly ash microspheres and their application for conditioning liquid radioactive waste  

International Nuclear Information System (INIS)

Using methods of the Moessbauer spectroscopy, scanning electron microscopy, and thermodynamic analysis of phase formation in silicate multi-component melts, the detailed study of composition, morphology, and properties of fly ash microspheres resulting from combustion of three coals (Irsha-Borodinskii, Kuznetskii and Ekibastuzskii) was carried out. About 60 microspherical products with an iron content of 2-94 wt.% Fe2O3 were obtained. The ranges of microsphere composition, suitable for liquid radioactive waste solidification in the forms of iron phosphate (36-94 wt.% Fe2O3) and aluminosilicate (2-20 wt.% Fe2O3) ceramics were determined. The possibility of producing porous materials and specific microspherical sorbents, based on coal fly ash cenospheres and their application for mobilisation of liquid radioactive waste solidification was demonstrated. (author)

317

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)

318

Neural network prediction of unconfined compressive strength of coal fly ash-cement mixtures  

Energy Technology Data Exchange (ETDEWEB)

Prediction of mechanical properties such as unconfined compressive strength (UCS) of cement-based pastes, mortars and concrete containing coal fly ash has been done using neural network analysis (NNA) based on the Trajan Neural Network Simulator. The application of NNA has been able to identify the main variables showing an influence on UCS, and the best model to describe UCS with a root mean squared error of 6 MPa for all formulations and 5.5 MPa when formulations are restricted to the maximum addition of coal fly ash established in the European Standards (35% for cement and 55% for concrete). These results allow a good description of the experimental data for the European limits based on cement and concrete, where UCS ranges between 32.5-52.5 MPa and 12-60 MPa, respectively.

Sebastia, M.; Olmo, I.F.; Irabien, A. [University of Cantabria, Santander (Spain)

2003-08-01

319

Analysis of brown coal fly-ash using X-ray photoelectron spectroscopy  

Science.gov (United States)

The surface chemical composition of brown coal ash particles formed during combustion has been determined using the surface-sensitive technique of X-ray photoelectron spectroscopy (XPS). Samples taken from furnace heat exchanger tube surfaces were in both powder and aggregate form. Other samples were obtained directly using 1 cm 2 steel coupons on a sample holder designed for insertion into flue gases in an experimental furnace. This allowed comparison of the XPS analyses between the fly-ash samples so acquired. After initial XPS characterization, samples were subjected to rare-gas ion (Ar +) sputtering for depth profiling purposes. The XPS technique was thus used to detect any sputter-induced composition changes or to observe any difference between the surface and bulk compositions of the ash. It was also observed that certain steels used for heat exchanger piping may well be pre-disposed to aluminosilicate fouling due to their intrinsic Al content.

Ersez, T.; Liesegang, J.

1991-08-01

320

Selenium bioaccumulation in fish exposed to coal ash at the Tennessee Valley Authority Kingston spill site.  

Science.gov (United States)

In December 2008, 4.1 million cubic meters of coal ash were released into the Emory and Clinch Rivers by the Tennessee Valley Authority Kingston Fossil Plant. Coal ash contains several contaminants, including the bioaccumulative metalloid selenium (Se). Because Se is predominantly accumulated in aquatic organisms through dietary rather than aqueous exposure, tissue-based toxicity thresholds for Se are currently being considered. The proposed threshold concentrations range between 4??g/g and 9??g/g Se (dry wt.) in whole body fish, with a proposed fillet threshold of 11.8??g/g. In the present study, the authors examined the spatial and temporal trends in Se bioaccumulation and examined the relationship between the Se content in fillets and in whole bodies of fish collected around the Kingston spill site to determine whether Se bioaccumulation was a significant concern at the ash spill site. Whereas Se concentrations in fish (whole bodies and fillets) were elevated at sampling locations affected by the Kingston ash spill relative to reference locations, concentrations do not appear to be above risk thresholds and have not been increasing over the 5-yr period since the spill. These findings are not only relevant to guiding the human health and ecological risk assessments at the Kingston ash spill site, but because of current national discussions on appropriate guidelines for Se in fish as well for the disposal of coal combustion wastes, the results are also relevant to the general understanding of Se bioaccumulation in contaminated water bodies. Environ Toxicol Chem 2014;33:2273-2279. © 2014 SETAC. PMID:24943719

Mathews, Teresa J; Fortner, Allison M; Jett, R Trent; Morris, Jesse; Gable, Jennifer; Peterson, Mark J; Carriker, Neil

2014-10-01

 
 
 
 
321

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

322

An investigation of radon exhalation rate and estimation of radiation doses in coal and fly ash samples  

International Nuclear Information System (INIS)

Coal is a technologically important material used for power generation. Its cinder (fly ash) is used in the manufacturing of bricks, sheets, cement, land filling etc. Coal and its by-products often contain significant amounts of radionuclides, including uranium which is the ultimate source of the radioactive gas radon. Burning of coal and the subsequent atmospheric emission cause the redistribution of toxic radioactive trace elements in the environment. In the present study, radon exhalation rates in coal and fly ash samples from the thermal power plants at Kolaghat (W.B.) and Kasimpur (U.P.) have been measured using sealed Can technique having LR-115 type II detectors. The activity concentrations of 238U, 232Th, and 40K in the samples of Kolaghat power station are also measured. It is observed that the radon exhalation rate from fly ash samples from Kolaghat is higher than from coal samples and activity concentration of radionuclides in fly ash is enhanced after the combustion of coal. Fly ash samples from Kasimpur show no appreciable change in radon exhalation. Radiation doses from the fly ash samples have been estimated from radon exhalation rate and radionuclide concentrations

323

Arsenic and copper stabilisation in a contaminated soil by coal fly ash and green waste compost.  

Science.gov (United States)

In situ metal stabilisation by amendments has been demonstrated as an appealing low-cost remediation strategy for contaminated soil. This study investigated the short-term leaching behaviour and long-term stability of As and Cu in soil amended with coal fly ash and/or green waste compost. Locally abundant inorganic (limestone and bentonite) and carbonaceous (lignite) resources were also studied for comparison. Column leaching experiments revealed that coal fly ash outperformed limestone and bentonite amendments for As stabilisation. It also maintained the As stability under continuous leaching of acidic solution, which was potentially attributed to high-affinity adsorption, co-precipitation, and pozzolanic reaction of coal fly ash. However, Cu leaching in the column experiments could not be mitigated by any of these inorganic amendments, suggesting the need for co-addition of carbonaceous materials that provides strong chelation with oxygen-containing functional groups for Cu stabilisation. Green waste compost suppressed the Cu leaching more effectively than lignite due to the difference in chemical composition and dissolved organic matter. After 9-month soil incubation, coal fly ash was able to minimise the concentrations of As and Cu in the soil solution without the addition of carbonaceous materials. Nevertheless, leachability tests suggested that the provision of green waste compost and lignite augmented the simultaneous reduction of As and Cu leachability in a fairly aggressive leaching environment. These results highlight the importance of assessing stability and remobilisation of sequestered metals under varying environmental conditions for ensuring a plausible and enduring soil stabilisation. PMID:24859701

Tsang, Daniel C W; Yip, Alex C K; Olds, William E; Weber, Paul A

2014-09-01

324

Rapid analysis of coal ash using an inductively coupled plasma analyzer  

Energy Technology Data Exchange (ETDEWEB)

The rapid analysis is reported of the silicate compounds contained in coal ash. The method proposed utilizes inductively coupled plasma emission spectroscopy, which allows simultaneous determination of a large number of constituents with a wide range of analytic concentrations. The authors report that, after sample preparation lasting approximately 3 hours, the ICP analyzer gave results for 17 elements in four minutes per sample, and that the number of target elements can be increased. 1 reference, 1 figure, 3 tables.

Itoh, S.; Okeya, M.

1985-01-01

325

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

326

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

Science.gov (United States)

The use of an industry waste, brown coal fly ash collected from the Latrobe Valley, Victoria, Australia, has been tested for the post-combustion CO(2) 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 CO(2) capture capacity of fly ash under mild conditions has been confirmed. The CO(2) 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 CO(2) 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/piperazine system. The CO(2) capture capacity of this system has also proven to reach maximum 264 kg CO(2)/ton 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. PMID:22326240

Sun, Yong; Parikh, Vinay; Zhang, Lian

2012-03-30

327

Photosynthetic pigment concentrations, gas exchange and vegetative growth for selected monocots and dicots treated with two contrasting coal fly ashes  

Energy Technology Data Exchange (ETDEWEB)

There is uncertainty as to the rates of coal fly ash needed for optimum physiological processes and growth. In the current study we tested the hyothesis that photosynthetic pigments concentrations and CO{sub 2} assimilation (A) are more sensitive than dry weights in plants grown on media amended with coal fly ash. We applied the Terrestrial Plant Growth Test (Guideline 208) protocols of the Organization for Economic Cooperation and Development (OECD) to monocots (barley (Hordeum vulgare) and ryegrass (Secale cereale)) and dicots (canola (Brasica napus), radish (Raphanus sativus), field peas (Pisum sativum), and lucerne (Medicago sativa)) on media amended with fly ashes derived from semi-bituminous (gray ash) or lignite (red ash) coals at rates of 0, 2.5, 5.0, 10, or 20 Mg ha(-1). The red ash had higher elemental concentrations and salinity than the gray ash. Fly ash addition had no significant effect on germination by any of the six species. At moderate rates ({<=}10 Mg ha{sup -1}) both ashes increased (P < 0.05) growth rates and concentrations of chlorophylls a and b, but reduced carotenoid concentrations. Addition of either ash increased A in radish and transpiration in barley. Growth rates and final dry weights were reduced for all of the six test species when addition rates exceeded 10 Mg ha{sup -1} for gray ash and 5 Mg ha{sup -1} for red ash. We concluded that plant dry weights, rather than pigment concentrations and/or instantaneous rates of photosynthesis, are more consistent for assessing subsequent growth in plants supplied with fly ash.

Yunusa, I.A.M.; Burchett, M.D.; Manoharan, V.; DeSilva, D.L.; Eamus, D.; Skilbeck, C.G. [University of Technology Sydney, Sydney, NSW (Australia). Dept. of Environmental Science

2009-07-15

328

Using ordination and clustering techniques to assess multimetric fish health response following a coal ash spill.  

Science.gov (United States)

The effect of coal ash exposure on fish health in freshwater communities is largely unknown. Given the large number of possible pathways of effects (e.g., toxicological effect of exposure to multiple metals, physical effects from ash exposure, and food web effects), measurement of only a few health metrics is not likely to give a complete picture. The authors measured a suite of 20 health metrics from 1100+ fish collected from 5 sites (3 affected and 2 reference) near a coal ash spill in east Tennessee over a 4.5-yr period. The metrics represented a wide range of physiological and energetic responses and were evaluated simultaneously using 2 multivariate techniques. Results from both hierarchical clustering and canonical discriminant analyses suggested that for most species × season combinations, the suite of fish health indicators varied more among years than between spill and reference sites within a year. In a few cases, spill sites from early years in the investigation stood alone or clustered together separate from reference sites and later year spill sites. Outlier groups of fish with relatively unique health profiles were most often from spill sites, suggesting that some response to the ash exposure may have occurred. Results from the 2 multivariate methods suggest that any change in the health status of fish at the spill sites was small and appears to have diminished since the first 2 to 3 yr after the spill. PMID:24764206

Bevelhimer, Mark S; Adams, S Marshall; Fortner, Allison M; Greeley, Mark S; Brandt, Craig C

2014-08-01

329

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

330

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

Directory of Open Access Journals (Sweden)

Full Text Available 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.La eliminación de subproductos del carbón supone problemas ambientales y económicos en todo el mundo por lo que la reutilización y valorización de los mismos se ha convertido en un tema importante en las últimas décadas. Mientras que las cenizas volantes se han utilizado en aplicaciones de alto valor y se han desarrollado productos de construcción en los que se ha utilizado esta ceniza como adición al cemento, no se ha sido permitido la utilización de la ceniza de fondo como en cementos. Este artículo examina las propiedades químicas y físicas de las cenizas volantes y de fondo procedentes de dos centrales termoeléctricas con el objetivo de compararlas y analizar la potencial utilización de la ceniza de fondo como adición al cemento. Se han estudiado también las propiedades mecánicas de morteros de cemento fabricados con distintos porcentajes de ambas cenizas como sustitución del cemento. Los resultados obtenidos mostraron que las ambos tipos de cenizas tenían una composición química similar. Los valores de resistencia a compresión a 28 días de los morteros con un 10 % y 25 % de porcentaje de sustitución estaban dentro de los límites permitidos en la normativa Europea y no había diferencias significativas entre las cenizas volantes y de fondo procedentes de ambas centrales térmicas.

Menéndez, E.

2013-12-01

331

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

332

Fly ash from a Mexican mineral coal I: Mineralogical and chemical characterization.  

Science.gov (United States)

The properties of coal fly ash are strongly dependent on the geological origin and the combustion process of the coal. It is important to characterize regional fly ash in detail to ascertain its potential uses as raw material in the production of high value products. The physicochemical properties of fly ash coming from the "Jose Lopez Portillo" coal-fired power plant, Coahuila, Mexico (MFA), are presented in this work. A detailed study of trace elements, the chemical composition of the amorphous phase, thermal stability and the leaching of contaminant elements under different conditions are included. MFA is composed of mullite, quartz, calcite, magnetite and an amorphous phase. This material contains mainly silica (59.6%), alumina (22.8%) and magnetite (5.6%). Its amorphous phase (78.3%) has a high silica (49.4%) and alumina (14.4%) content. According to its mineralogical and chemical composition, MFA is potentially useful as a raw material for making cement, silica, and alumina, as well as low silica/alumina ratio zeolites. Deleterious elements could be removed during the zeolitization process or with an additional acid treatment. Because of its morphological properties and structural and thermal stability, MFA can be used in thermal isolation and refractory materials and as a support for heterogeneous catalysts. PMID:20546994

Medina, Adriana; Gamero, Prócoro; Querol, Xavier; Moreno, Natalia; De León, Beatriz; Almanza, Manuel; Vargas, Gregorio; Izquierdo, María; Font, Oriol

2010-09-15

333

Radon exhalation of cementitious materials made with coal fly ash: Part 2--testing hardened cement-fly ash pastes.  

Science.gov (United States)

Increased interest in measuring radionuclides and radon concentrations in fly ash (FA), cement and other components of building products is due to the concern about health hazards of naturally occurring radioactive materials (NORM). The paper focuses on studying the influence of FA on radon exhalation rate (radon flux) from cementitious materials. In the previous part of the paper the state of the art was presented, and the experiments for testing raw materials, Portland cement and coal fly ash, were described. Since the cement and FA have the most critical role in the radon release process relative to other concrete constituents (sand and gravel), and their contribution is dominant in the overall radium content of concrete, tests were carried out on cement paste specimens with different FA contents, 0-60% by weight of the binder (cement+FA). It is found that the dosage of FA in cement paste has a limited influence on radon exhalation rate, if the hardened material is relatively dense. The radon flux of cement-FA pastes is lower than that of pure cement paste: it is about approximately 3 mBq m(-2) s(-1) for cement-FA pastes with FA content as high as 960 kg m(-3). PMID:15885379

Kovler, K; Perevalov, A; Levit, A; Steiner, V; Metzger, L A

2005-01-01

334

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.)

335

Evaluation of the effects of coal fly ash amendments on the toxicity of a contaminated marine sediment  

Energy Technology Data Exchange (ETDEWEB)

Approaches for cleaning up contaminated sediments range from dredging to in situ treatment. In this study, we discuss the effects of amending reference and contaminated sediments with coal fly ash to reduce the bioavailability and toxicity of a field sediment contaminated with polycyclic aromatic hydrocarbons (PAHs). Six fly ashes and a coconut charcoal were evaluated in 7-d whole sediment toxicity tests with a marine amphipod (Ampelisca abdita) and mysid (Americamysis bahia). Fly ashes with high carbon content and the coconut charcoal showed proficiency at reducing toxicity. Some of the fly ashes demonstrated toxicity in the reference treatments. It is suspected that some of this toxicity is related to the presence of ammonia associated with fly ashes as a result of postoxidation treatment to reduce nitrous oxide emissions. Relatively simple methods exist to remove ammonia from fly ash before use, and fly ashes with low ammonia content are available. Fly ashes were also shown to effectively reduce overlying water concentrations of several PAHs. No evidence was seen of the release of the metals cadmium, copper, nickel, or lead from the fly ashes. A preliminary 28-d polychaete bioaccumulation study with one of the high-carbon fly ashes and a reference sediment was also performed. Although preliminary, no evidence was seen of adverse effects to worm growth or lipid content or of accumulation of PAHs or mercury from exposure to the fly ash. These data show fly ashes with high carbon content could represent viable remedial materials for reducing the bioavailability of organic contaminants in sediments.

Burgess, R.M.; Perron, M.M.; Friedman, C.L.; Suuberg, E.M.; Pennell, K.G.; Cantwell, M.G.; Pelletier, M.C.; Ho, K.T.; Serbst, J.R.; Ryba, S.A. [US EPA, Narragansett, RI (USA). Office for Research and Development

2009-01-15

336

On wet chemical phosphorus recovery from sewage sludge ash by acidic or alkaline leaching and an optimized combination of both.  

Science.gov (United States)

The advantages and drawbacks of existing wet chemical phosphorus (P) recovery technologies, their applicability to different types of sewage sludge ash (SSA) and the role of the decay products of detergent zeolites as a source of reactive Al in SSA are analyzed. Since neither a purely acidic nor a purely alkaline treatment are able to provide satisfactory technical solutions a wet chemical phosphorus (P) recovery process for sewage sludge ashes (SSAs) is investigated in detail that is based on a sequential treatment of SSA with an acid and a base. As a result of an acidic pre-treatment, the P fraction of the raw SSA that was bound as - alkaline-insoluble - calcium phosphate (Ca-P) is converted into aluminum phosphate (Al-P). This newly formed Al-P can be easily dissolved via alkaline treatment and then easily separated from the alkaline leachate via precipitation of Ca-P. The Al-component can be reused as precipitant for P-removal in waste water treatment plants (WWTPs). The investigated process requires fewer chemicals than the direct acidic dissolution of all P-compounds contained in the SSA. This is due to the described rearrangement of the P component from Ca-P to Al-P. That such a rearrangement of P occurs indeed was confirmed through a combination of XRD, ICP and XRF analyses together with mass balance calculations. The present investigation proves that the process works for very different types of SSAs: For Al-rich SSAs that come from WWTPs where Al-salt is used for chemical P-removal the described sequential treatment process works best and yields P-recovery rates as high as 70-77%. But even for SSAs from WWTPs where only iron salt is used for chemical P-removal, a considerable amount of the reactive Al necessary for the described P-rearrangement is supplied by decay products of detergent zeolites, a hidden Al-source present in most SSAs produced in Europe. PMID:22579406

Petzet, Sebastian; Peplinski, Burkhard; Cornel, Peter

2012-08-01

337

Durability of concrete with powder coal fly ash in practice; Duurzaamheid van beton met poederkoolvliegas in de praktijk  

Energy Technology Data Exchange (ETDEWEB)

Due to the oil crisis in the seventies of the last century coal was reintroduced as fuel for electricity generating plants in the Netherlands. Coal fly ash is one of the products of the combustion of powder coal in these plants. In the Netherlands all coal fly ash produced, is used mainly for cement and concrete. At present more than 20 years of experience exists of concrete structures with coal fly ash. Hence, there is enough experience to validate the laboratory research performed in the past and to investigate the effect of coal fly ash on durability. Six Dutch concrete structures have been investigated with respect to performance over the years in service. This report summarises the results of this investigation as well as the durability of concrete structures with coal fly ash documented in the German and British literature. The results obtained show that the concrete with coal fly ash of all Dutch structures investigated, having an age of 4.5 to 16 years, was in excellent condition. No defects, due to coal fly ash were observed. In all cases the compressive strength has increased relative to the 28 days strength. In combination with portland cement the increase can be more than 100% over a period of 10 years.The increase in compressive strength will be due to an increase in the density of the cement stone in concrete. Therefore the resistance to ingress of aggressive compounds in concrete will more increase for portland cement concrete with fly ash than without. The results are in accordance with those of British research into coal fly ash concrete structures. in case of blast furnace slag cement, CEM III/B A or B, the difference in compressive strength development of concrete with and without coal fly ash of the same 28 days strength in time is small. Moreover the increase in strength after 28 days is small in comparison with portland cement concrete with coal fly ash. No indications of any deteriorating mechanism were found. In two cases corrosion of reinforcement was observed due to bad execution. In both cases the cover on the reinforcement appeared to be 10 mm or less. Depassivation has occurred due to carbonation. A German investigation into a prestressed railway sleeper does not show any sign of stress corrosion due to coal fly ash.The use of coal fly ash in concrete can prevent the occurrence of alkali-aggregate reaction. The concrete of all structures investigated shows a high resistance against diffusion. Also the chloride penetration resistance appeared to be high. Coal fly ash provides portland cement concrete with a higher resistance against penetration of aggressive compounds and oxygen.This improves the durability of the concrete. 20 refs.

Bijen, J. [ed.

2000-04-01

338

Catastrophic dispersion of coal fly ash into oceans during the latest Permian extinction  

Energy Technology Data Exchange (ETDEWEB)

During the latest Permian extinction about 250 Myr ago, more than 90% of marine species went extinct, and biogeochemical cycles were disrupted globally. The cause of the disruption is unclear, but a link between the eruption of the Siberian Trap flood basalts and the extinction has been suggested on the basis of the rough coincidence of the two events. The flood basalt volcanism released CO{sub 2}. In addition, related thermal metamorphism of Siberian coal measures and organic-rich shales led to the emission of methane, which would have affected global climate and carbon cycling, according to model simulations. This scenario is supported by evidence for volcanic eruptions and gas release in the Siberian Tunguska Basin, but direct indicators of coal combustion have not been detected. Here we present analyses of terrestrial carbon in marine sediments that suggest a substantial amount of char was deposited in Permian aged rocks from the Canadian High Arctic immediately before the mass extinction. Based on the geochemistry and petrology of the char, we propose that the char was derived from the combustion of Siberian coal and organic-rich sediments by flood basalts, which was then dispersed globally. The char is remarkably similar to modern coal fly ash, which can create toxic aquatic conditions when released as slurries. We therefore speculate that the global distribution of ash could have created toxic marine conditions.

Grasby, S.E.; Sanei, H.; Beauchamp, B. [Geological Survey Canada Calgary, Calgary, AB (Canada)

2011-02-15

339

DISPOSAL, RECYCLE, AND UTILIZATION OF MODIFIED FLY ASH FROM HYDRATED LIME INJECTION INTO COAL-FIRED UTILITY BOILERS  

Science.gov (United States)

The paper gives results of an assessment of the disposal, utilization, and recycle os a modified fly ash from the injection of hydrated lime into a coal-fired utility boiler. The process, developed as a low-cost alternative for achieving moderate degrees of SO2 control at coal-fi...

340

Design and implementation of a field pilot study on using coal fly ash to prevent oxidation of reactive mine tailings  

Energy Technology Data Exchange (ETDEWEB)

This paper reported on a pilot scale study that investigated the feasibility of using coal fly ash in mine tailings management and acid mine drainage (AMD) treatment at Goldcorp's Musselwhite Mine site in northern Ontario. The principles and key aspects of the fly ash application in mine tailings management were described. Fly ash from the Atikokan coal-fired power generating plant was added to the Musselwhite tailings as a mixture as well as intermediate and top layers. The physical, chemical and hydrogeological effects of the two approaches were monitored. The paper provided details of the design, implementation, monitoring, sampling and testing over 2 years. The objectives were to evaluate the optimum mass ratio of coal fly ash and mine tailings, effectiveness in reducing the infiltration of precipitation, and projected long-term durability and performance on tailings oxidation prevention. The pilot study was designed based on the principles of cementitious materials formation and secondary mineral formation by the reactions of coal fly ash and water/AMD. Calcium oxide, aluminum oxide, silicon oxide, and ferric oxide are major components of coal fly ash. The preliminary test results revealed that water did not accumulate and cracks did not form on top of 4 tanks. The settlements of the mixing approaches were lower than that of the stratified approach and the temperature distributions in the 4 tanks were comparable. 9 refs., 3 tabs., 11 figs.

Wang, H.L.; Shang, J.Q.; Xu, Y.Q.; Yanful, E.K. [Western Ontario Univ., London, ON (Canada). Dept. of Civil and Environmental Engineering; Hmidi, N. [Goldcorp Inc., Musselwhite Mine, Thunder Bay, ON (Canada)

2009-07-01

 
 
 
 
341

Design and implementation of a field pilot study on using coal fly ash to prevent oxidation of reactive mine tailings  

International Nuclear Information System (INIS)

This paper reported on a pilot scale study that investigated the feasibility of using coal fly ash in mine tailings management and acid mine drainage (AMD) treatment at Goldcorp's Musselwhite Mine site in northern Ontario. The principles and key aspects of the fly ash application in mine tailings management were described. Fly ash from the Atikokan coal-fired power generating plant was added to the Musselwhite tailings as a mixture as well as intermediate and top layers. The physical, chemical and hydrogeological effects of the two approaches were monitored. The paper provided details of the design, implementation, monitoring, sampling and testing over 2 years. The objectives were to evaluate the optimum mass ratio of coal fly ash and mine tailings, effectiveness in reducing the infiltration of precipitation, and projected long-term durability and performance on tailings oxidation prevention. The pilot study was designed based on the principles of cementitious materials formation and secondary mineral formation by the reactions of coal fly ash and water/AMD. Calcium oxide, aluminum oxide, silicon oxide, and ferric oxide are major components of coal fly ash. The preliminary test results revealed that water did not accumulate and cracks did not form on top of 4 tanks. The settlements of the mixing approaches were lower than that of the stratified approach and the temperature distributions in the 4 tanks were comparable. 9 refs., 3 tabs., 11 figs.

342

Influence of clay minerals on the softening and fusing properties of coal ash  

Energy Technology Data Exchange (ETDEWEB)

The older the geological age of the inorganic mineral phase contained in coal, the more kaolinite is present, and the greater the likelihood of there being sericite. However, other mineral phases become less abundant with increasing age. The net effect is a relatively high softening and fusing temperature. On the other hand, geologically recent coal minerals tend to be complex ones such as feldspars, zeolites and calcite. These give relatively low softening and melting points. The authors report an attempt to classify minerals by geological age and then, by way of correlations with measured softening and melting points, to use this classification to assess the softening and melting characteristics of ashes from different coals. 14 references.

Kawai, T.; Imanishi, N.; Shibata, S.

1985-01-01

343

Effects of process parameters and ash on the adsorption properties of activated carbon from coals  

International Nuclear Information System (INIS)

super-activated carbon was prepared from three representative shanxi coals, i.e. datong bituminous coal, yangquan anthracite and jincheng anthracite by KOH activation. The optimum parameters were obtained by comparing CCl/sub 4/ absorption values of activated carbon (ac). In addition, pristine coal and ac were deashed by acid washing, respectively. The effect of ash content on the adsorption properties of ac was studied. the results indicate that CCl/sub 4/ adsorption value of ac from yangquan anthracite with deashing treatment reaches up to 3301 mg/g when the activated temperature, activated time and ratio of alkali to carbon are 1830 degree C, 60 min and 5/1, respectively. (author)

344

Distributional Fate of Elements during the Synthesis of Zeolites from South African Coal Fly Ash  

Directory of Open Access Journals (Sweden)

Full Text Available The synthesis of zeolites from South African coal fly ash has been deemed a viable solution to the growing economical strain caused by the disposal of ash in the country. Two synthesis routes have been studied thus far namely the 2-step method and the fusion assisted process. Fly ash contains several elements originating from coal which is incorporated in the ash during combustion. It is vital to determine the final destination of these elements in order to unveil optimization opportunities for scale-up purposes. The aim of this study was to perform a material balance study on both synthesis routes to determine the distributional fate of these elements during the synthesis of zeolites. Zeolites were first synthesized by means of the two synthesis routes. The composition of all raw materials and products were determined after which an overall and elemental balance were performed. Results indicated that in the 2-step method almost all elements were concentrated in the solid zeolite product while during the fusion assisted route the elements mostly report to the solid waste. Toxic elements such as Pb, Hg, Al, As and Nb were found in both the supernatant waste and washing water resulting from each synthesis route. It has also been seen that large quantities of Si and Al are wasted in the supernatant waste. It is highly recommended that the opportunity to recycle this liquid waste be investigated for scale-up purposes. Results also indicate that efficiency whereby Si and Al are extracted from fused ash is exceptionally poor and should be optimized.

Pieter W. Du Plessis

2014-04-01

345

Selection of fluxing agent for coal ash and investigation of fusion mechanism: a first-principles study  

Energy Technology Data Exchange (ETDEWEB)

An approach based on the ab initio quantum chemical modeling (CASTEP, generalized gradient approximation (GGA), and density functional theory (DFT)) was first employed to guide the selection of the appropriate fluxing agent to reduce the coal ash melting temperature. Two kinds of typical Chinese coal ash A and B with a high-melting temperature were chosen as the investigated subjects. Result of the calculation shows that mullite mineral, which is the main component of coal ash, is easier to combine with an electron acceptor than with an electron donor. Because the cations of borax (Na{sub 2}B{sub 4}O{sub 7}10H{sub 2}O) and limestone can act as electron acceptors, borax and limestone were selected as the fluxing agents in our experiment. Results of the experiment show that the melting temperatures of coal ash A and B are both decreased by borax and limestone, respectively. Moreover, borax has a better fluxing effect than limestone under the same conditions. The further numerical study on the coal ash fusing mechanism indicates that the Na{sup +} and Ca{sup 2+} cations, as acceptors, can enter into the crystal lattice of mullite mainly through O(7) and O(8) and then cause the Al(6)-O(8) and Al(5)-O(7) bonds to rupture in the (AlO{sub 6})-octahedron. From this, mullite is forced to transform to feldspar and corundum minerals that have a low binding energy. Because of the phase change of minerals in the coal ash, the coal ash melting temperature is decreased by adding borax and limestone. 27 refs., 8 figs., 3 tabs.

Jie Li; Mei-Fang Du; Zhong-Xiao Zhang; Rong-Qing Guan; Yu-Shuang Chen; Ting-Yu Liu [University of Shanghai for Science and Technology, Shanghai (China). College of Science, and Department of Power Engineering

2009-01-15

346

Measurement of radon exhalation rate and estimation of radiation doses in coal and fly ash samples from a thermal power plant  

International Nuclear Information System (INIS)

Combustion of coal and the subsequent emissions to the atmosphere cause the re-distribution of radioactive trace elements like uranium, the source of radon gas in the environment. In the present study radon exhalation rates in coal and fly ash samples from Kolaghat Thermal Power Plant (W.B.) have been measured by 'Can technique' using LR-115 type II detectors. Radon exhalation rate in fly ash samples is found to be higher than in coal and combustion of coal enhances the radionuclide concentration in fly ash. Radiation doses from the fly ash samples have been estimated from radon exhalation rate and radionuclide concentrations. (author)

347

Determination of beryllium in coal fly ash by electrothermal atomic absorption spectrometry  

International Nuclear Information System (INIS)

Separation of the analyte using a ?-diketo liquid chelating exchange (LCE) (C9H19COCH2COCH3) and subsequent determination by electrothermal atomic absorption spectrometry (ETAAS) is described for the determination of beryllium in coal fly ash emitted from coal fired power stations. The conditions for the separation and preconcentration of beryllium, eg., pH, solvent, shaking time and kinetics of the extraction and the effects of various ions have been optimized. Quantitative extraction (100%) of beryllium with LCE occurs in a cyclohexane medium at pH 9.5, the extracted species being [Be(C9H19C(=O)CH=C(O)CH3]. Direct analyses of the fly ash samples using ETAAS, and of standard reference materials, always gave higher results than the proposed method due to the presence of various interfering metals. The reliability of the method has been demonstrated by the recoveries (97.4-98.4%) of standard additions of beryllium to fly ash sample solutions. (Author)

348

Flue gas interactions of mercury, chlorine, and ash during coal combustion  

Energy Technology Data Exchange (ETDEWEB)

The interaction between the coal combustion flue gas components mercury, chlorine, and entrained fly ash particulate was investigated experimentally using a 42 MJ- or 40,000-Btu/hr, downfired, combustion system. A low-Cl, Powder River Basis (PRB) subbituminous coal with 0.052 ppm Hg was burned at an excess O{sub 2} concentration of 8.5%. HCI was injected into the hot zone of the furnace at concentrations of 50 and 100 ppmv. Tests involving the injection of 10 {mu}g/m{sup 3} Hg{sup 0} (elemental Hg) and 100 ppmv HCI into a simple heated gas mixture were also conducted. A modified US Environmental Protection Agency (EPA) Method 29 sample train, developed by Radian International and evaluated at the Energy and Environmental Research Center (EERC), was used for determining Hg emission and speciation at the baghouse inlet of the system. EPA Method 26 was used for determining Cl emission and speciation, and on-line analyzers were employed during most tests to monitor total Hg, Hg{sup 0}, HCl, O{sub 2} CO{sub 2}, CO, SO{sub 2}, and NO concentrations. Fly ash was sampled from the baghouse and analyzed for Hg, Cl, and C after each coal test. Baseline testing of the PRB coal indicated that on average 40%, 20%, and 40% of the total Hg in the flue gas was present as particle-associated mercury (Hg[p]), gaseous divalent mercury (Hg{sup 2+}[g]), and gaseous elemental mercury (Hg{sup 0}[g]), respectively. In comparison, Hg speciation of the HCl-spiked flue gases was 10% Hg(p), 30% Hg{sup 2+}(g), and 60% Hg{sup 0}(g). Hg mass balance closures were acceptable (85% {+-} 12%). Cl speciation analyses indicated that >98% of the injected HCl remained as HCl. In the lower-temperature environment of the baghouse, fly ash from the baseline coal test has depleted in Cl relative to the ashes produced from the 50- and 100-ppmv HCl injection tests. Hg concentrations of the baghouse fly ash samples were not directly correlated to ash Cl or C contents. The PRB coal tests indicate that the expected conversions of Hg{sup 0}(g) to Hg(p) and Hg{sup 2+}(g) with HCl injection did not occur. Conversely, HCl injection converted most of the Hg(p) to Hg{sup 0}(g). The injection of Hg{sup 0}(g)-HCl into the simple heated gas mixture resulted in the expected conversion of Hg{sup 0}(g) to Hg{sup 2+}(g) in the combustor. Consequently, the presence of PRB coal combustion flue gas components (i.e., other gases and/or entrained particulate) promoted the remobilization of Hg(p) to Hg{sup 0}(g) during HCl injection.

Zygarlicke, C.J.; Galbreath, K.C.

1998-07-01

349

Multivariate calibration in the radioisotope measurements of ash content in coal  

International Nuclear Information System (INIS)

Multivariate calibration models developed for the radioisotope gauges designed for the measurement of the ash content in coal were investigated. The models were computed using the full spectra of the Am-241 ?-rays scattered back and forward from the coal sample, as well as the spectra of X-ray fluorescence with back scattered radiation of Pu-238 source. The spectra of scattered ?-rays were registered with the scintillation detector whereas for detection of X-rays the proportional counter was used. Calibration set contained 43 coal samples from four mines and the ash content ranged from 4 to 78%. The linear and non-linear partial least square (PLS) models were investigated and compared with multiple linear regression (MLR) models. It was found that the lowest value of root mean square error of cross validation was obtained for the non-linear PLS model in the case of the spectra of scattered ?-rays and for the linear PLS model with preliminary data processing in the case of the XRF spectra. (author)

350

Natural radioactivity of airbone particulates in coal-ash disposal sites  

International Nuclear Information System (INIS)

An investigation was made on the actual concentrations of U, Th and Po in air-borne dust and soil around coal power stations, to study the effect of coal-ash disposal site on natural radioactivity of environmental samples. Samples were collected at a coal-ash disposal and its reference places. The results obtained are summaried as follows; (1) Concentrations of U, Th and Po in air-borne dust at the disposal place was nealy equal to those at the reference place. (2) Origin of those ?-emitting elements in the dust was successfully deduced, on the basis of correlating concentrations of Sc and Cl elements in the dust. (3) It was inferred that elements of both U and Po in the dust at disposal site came from soil by about 80% and artificial origin such as exhausted gas by remainder. Almost all Th element were from soil. It was therefore concluded that effect of disposal site on radioactivity concentrations of dusts was negligible. (author)

351

Cost effective clean power generation burning high ash and/or high sulfur coals  

Energy Technology Data Exchange (ETDEWEB)

In the future, new air pollution control technologies will be required by coal-fired electric utilities and industrial boiler owners to meet more stringent environmental constraints. The CAIRE{trademark} (acronym for Controlled Air Emissions) combustor technology offers the benefit of reducing SO{sub 2} by some 70 to 90% and lowering NO{sub x} emission levels to 0.30 lb/10{sup 6} Btu or less, better than the best conventional low NO{sub x} burners on the market today. It also incorporates the advantage of a cyclone-fired unit by reducing particulate carryover into the boiler and downstream equipment by some 75 to 80%. This means that low cost, high sulfur and/or high ash coals may be fired in this combustor without the penalty of increased SO{sub 2} emissions, ash fouling and higher particulate stack emissions. The CAIRE{trademark} combustor may be retrofitted to electric utility boilers at a cost per ton of SO{sub 2} removed that is less than the price of SO{sub 2} allowance credits and less than the cost of switching from Eastern to Western US coal.

Ashworth, R.A.; Sanyal, A.

1998-07-01

352

Growth responses of selected freshwater algae to trace elements and scrubber ash slurry generated by coal-fired power plants  

Energy Technology Data Exchange (ETDEWEB)

The development and implementation of standard toxicity tests is a necessity if consistent and reliable data are to be obtained for water quality criteria. The adapted EPA AAPBT is an ideal static algal toxicity test system. The algal test medium has a chemical composition similar to natural unpolluted waters of low ionic strength. It is appropriate to use MATC water quality criteria when assessing the potential impact of pollutants generated by coal-fired power stations because these energy-generated pollutants typically enter aquatic systems in small quantities over long periods. The MATC water quality criteria are estimates of trace element and SASE levels, based on the most sensitive alga investigated, that will not cause significant changes in naturally-functioning algal populations. These levels are 0.016f mg L/sup -1/ As(V), 0.001 mg L/sup -1/ Cd(II), 0.004 mg L/sup -1/ Hg(II), 0.006 mg L/sup -1/ Se(VI), and 0.344% SASE. To provide viable working water quality criteria, an extrapolation from the laboratory to the natural environment must be made. Therefore, those oxidation states of the trace elements were selected which are the dominant states occurring in natural, unpolluted, slightly alkaline freshwaters. It must be pointed out that these MATC values are based on algal responses to single toxicants and no allowance is made for synergistic, additive, or antagonistic relationships which could occur in natural aquatic systems. Additionally, natural chelation may influence toxicity. The highly toxic nature of potential pollutants from coal-fired generating plants emphasizes the need for minimizing stack effluent pollutants and retaining scrubber ash slurry for proper disposal in an effort to maintain trace elements in concentration ranges compatible with naturally-functioning ecosystems.

Vocke, R.W.

1979-01-01

353

Measurement of uranium and thorium in coal fly ash and bottom ash samples from a thermal power plant by using a high resolution semiconductor detector  

International Nuclear Information System (INIS)

A low background ?-ray detection system has been constructed for measuring the natural radioactivity in coal samples. It is based on a high-purity Ge detector mounted within a massive lead shield which reduces the normal background level by a factor of about 20. This makes it possible to measure the low intensity ?-rays from the natural radioactivity present in the samples. Using this equipment uranium and thorium concentrations in coal fly ash and bottom ash samples from a coal fired power plant located at Bathinda, India have been measured. The uranium activity found in the samples is within the range of concentrations observed in other countries while the thorium activity is found to be somewhat higher. (Author)

354

Environmental impacts of the Tennessee Valley Authority Kingston coal ash spill. 1. Source apportionment using mercury stable isotopes.  

Science.gov (United States)

Mercury stable isotope abundances were used to trace transport of Hg-impacted river sediment near a coal ash spill at Harriman, Tennessee, USA. ?(202)Hg values for Kingston coal ash released into the Emory River in 2008 are significantly negative (-1.78 ± 0.35‰), whereas sediments of the Clinch River, into which the Emory River flows, are contaminated by an additional Hg source (potentially from the Y-12 complex near Oak Ridge, Tennessee) with near-zero values (-0.23 ± 0.16‰). Nominally uncontaminated Emory River sediments (12 miles upstream from the Emory-Clinch confluence) have intermediate values (-1.17 ± 0.13‰) and contain lower Hg concentrations. Emory River mile 10 sediments, possibly impacted by an old paper mill has ?(202)Hg values of -0.47 ± 0.04‰. A mixing model, using ?(202)Hg values and Hg concentrations, yielded estimates of the relative contributions of coal ash, Clinch River, and Emory River sediments for a suite of 71 sediment samples taken over a 30 month time period from 13 locations. Emory River samples, with two exceptions, are unaffected by Clinch River sediment, despite occasional upstream flow from the Clinch River. As expected, Clinch River sediment below its confluence with the Emory River are affected by Kingston coal ash; however, the relative contribution of the coal ash varies among sampling sites. PMID:23157719

Bartov, Gideon; Deonarine, Amrika; Johnson, Thomas M; Ruhl, Laura; Vengosh, Avner; Hsu-Kim, Heileen

2013-02-19

355

Microwave acid digestion for the determination of metals in subbitumnious coal bottom ash by ICP-OES  

Energy Technology Data Exchange (ETDEWEB)

The development of precise and easy determination method for the metals in fossil fuel is the essential factor for the study of problems which are caused by the existence of metals in fuel. Coal contains many kinds of mineral matter elements including metals derived from its generation. The sample preparation method developed for metal determination in coal by spectroanalytical technique is dry ashing, and wet acid microwave digestion. Microwave-acid digestion (MW-AD) followed by inductively coupled plasma-optical emission spectrometry (ICP-OES) was examined for the determination of metals (Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Zn) in coal bottom ash (CBA). Subbitumnious coal from Hazro deposits in SE Anatolia of Turkey has been used in this study. Metals in coal gave good recoveries for their certified or reference values.

Abdurrahman Saydut [Dicle University, Diyarbakir (Turkey). Engineering Faculty

2010-04-15

356

Investigations on ash deposit formation rate during co-combustion of coal with sewage sludge  

Energy Technology Data Exchange (ETDEWEB)

Fuels currently used for energy production in thermal power plants are characterised by their huge variety ranging from fossil fuels to biomass and waste. Although co-firing of biomass and bio-wastes has been practised in a number of plants, the practice is not yet widespread. Nowadays many efforts have the purpose to increase the use of diverse biomass and waste fuels co-fired in existing boilers. However ash related operational problems by co-firing, such as the effects of the co-fired fuel on slagging and fouling in the system, are the main reasons leading to reduction of boiler reliability and availability. The purpose of this paper is to report on the experimental studies on ash deposition in cocombustion of coal with sewage sludge. Blends of a South African coal and a sewage sludge (sludge content of 5, 10, 15, 20 % by thermal input) have been fired in a 50 kW drop tube furnace. Ceramic deposition probes have been used to analyse ash deposition rates at different locations from the burner corresponding to the resistance time of up to 2 seconds. The gas composition, gas temperature and fuel burnout have been measured at the deposition probe. The results show that the interaction between the coal and the sewage sludge is a strong function of the make-up of the mixture fired. The deposition rate has been determined for a number of operational parameters. The quality of the deposits has been examined using several techniques. It has been concluded that addition of the sludge has substantially altered both the structure and the rate of the deposit growth. 15 refs., 6 figs., 3 tabs.

T. Kupka; M. Cieslik; R. Weber [Clausthal University of Technology, Clausthal-Zellerfeld (Germany). Institute of Energy Process Engineering and Fuel Technology

2006-07-01

357

EVALUATING THE EFFECTS OF THE KINGSTON COAL ASH RELEASE ON FISH REPRODUCTION AND EARLY LIFE STAGES: LONG-TERM EXPOSURES TO ASH IN THE LABORATORY  

Energy Technology Data Exchange (ETDEWEB)

On December 22, 2008, a dike containing coal fly ash and bottom ash at the Tennessee Valley Authority’s (TVA) Kingston Fossil Plant in East Tennessee failed and released a large quantity of ash into the adjacent Emory River. A byproduct of coal combustion, coal ash contains contaminants of potential concern including mercury, arsenic, and selenium. Selenium in particular is known to be capable, when at sufficient concentrations and in specific forms, of impacting the reproduction or early development of exposed fish populations (Lemly 1993 & 1999; Besser and others 1996, USEPA 2004). The primary route of selenium exposure to larval fish appears to be uptake by adult female fish through the food chain and subsequent maternal transfer to the developing eggs (Woock and others 1987, Coyle and others 1993, Lemly 1999, Moscatello and others 2006). However, fish eggs are also capable of concentrating heavy metals and other environmental contaminants directly from water-borne exposures during embryonic development (Devlin 2006, Jezierska and others 2009) and from direct contact of fertilized eggs and developing embryos to contaminants in surface water and sediments (Woock and others 1987, Coyle and others 1993, Jezierska and others 2009). Associated studies conducted by researchers at Oak Ridge National Laboratory (ORNL) in conjunction with TVA examined the bioaccumulation of metals in fish tissues (Adams and others 2012), and the health (Adams and Fortner 2012) and reproductive condition (Greeley and others 2012a) of fish exposed to fly ash in the Emory and Clinch Rivers downstream of the Kingston Ash Release. The potential effects of the ash release on fish reproduction have also been addressed in a relatively short-term laboratory exposure study (Greeley and others 2012b) and by an in vitro spawning study conducted on fish sampled from sites downstream and upstream of the ash release (Greeley and others 2012c). Previous short-term laboratory study conducted by ORNL focused on the effects of direct contact exposures of eggs and embryos of the fathead minnow (Pimephales promelas) to river bottom sediment containing ash from the Kingston ash release in 7-d toxicity tests adapted from a standard USEPA embryo-larval survival and teratogenicity test (method 1001.0 in

Greeley Jr, Mark Stephen [ORNL; Elmore, Logan R. [ORNL; McCracken, Kitty [ORNL

2014-05-01

358

Health and environmental impacts of increased generation of coal ash and FGD sludges. Report to the Committee on Health and Ecological Effects of Increased Coal Utilization.  

Science.gov (United States)

This paper focuses on the incremental impacts of coal ash and flue gas desulfurization (FGD) wastes associated with increased coal usage by utilities and industry under the National Energy Plan (NEP). In the paper, 1985 and 2000 are the assessment points using the baseline data taken from the Annual Environmental Analysis Report (AEAR, September 1977). In each EPA region, the potential mix of disposal options has been broadly estimated and impacts assessed therefrom. In addition, future use of advanced combustion techniques has been taken into account. The quantities of coal ash and FGD wastes depend on ash and sulfur content of the coal, emission regulations, the types of ash collection and FGD systems, and operating conditions of the systems and boiler. The disposal of these wastes is (or will be) subject to Federal and State regulations. The one key legal framework concerning environmental impact on land is the Resource Conservation and Recovery Act (RCRA). RCRA and related Federal and State laws provide a sufficient statutory basis for preventing significant adverse health and environmental impacts from coal ash and FGD waste disposal. However, much of the development and implementation of specific regulations lie ahead. FGD wastes and coal ash and FGD wastes are currently disposed of exclusively on land. The most common land disposal methods are inpoundments (ponds) and landfills, although some mine disposal is also practiced. The potential environmental impacts of this disposal are dependent on the characteristics of the disposal site, characteristics of the coal ash and FGD wastes, control method and the degree of control employed. In general, the major potential impacts are ground and surface water contamination and the "degradation" of large quantities of land. However, assuming land is available for disposal of these wastes, control technology exists for environmentally sound disposal. Because of existing increases in coal use, the possibility of significant environmental impacts, both regionally and nationally, exists regardless of whether the NEP scenario develops or not. Existing baseline data indicate that with sound control technology and successful development and implementation of existing regulatory framework, regional scale impacts are likely to be small; however, site-specific impacts could be significant and need to be evaluated on a case-by-case basis. Both Federal and privately-funded programs are developing additional data and information on disposal of FGD sludges and coal ash. Continuation of these programs will provide additional vital information in the future. However, further information in several areas if desirable: further data on levels of radionuclides and trace metals in these wastes: studies on biological impacts of trace metals; and completion of current and planned studies on disposal problems associated with advanced combustion techniques like fluid bed combustion. PMID:540614

Santhanam, C J; Lunt, R R; Johnson, S L; Cooper, C B; Thayer, P S; Jones, J W

1979-12-01

359

Characteristics of fly ashes from full-scale coal-fired power plants and their relationship to mercury adsorption  

Science.gov (United States)

Nine fly ash samples were collected from the particulate collection devices (baghouse or electrostatic precipitator) of four full-scale pulverized coal (PC) utility boilers burning eastern bituminous coals (EB-PC ashes) and three cyclone utility boilers burning either Powder River Basin (PRB) coals or PRB blends,(PRB-CYC ashes). As-received fly ash samples were mechanically sieved to obtain six size fractions. Unburned carbon (UBC) content, mercury content, and Brunauer-Emmett-Teller (BET)-N2 surface areas of as-received fly ashes and their size fractions were measured. In addition, UBC particles were examined by scanning electron microscopy, high-resolution transmission microscopy, and thermogravimetry to obtain information on their surface morphology, structure, and oxidation reactivity. It was found that the UBC particles contained amorphous carbon, ribbon-