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1

Investigation of the solubility of components of the ash in Ekibastuz coal in alkaline solutions  

Energy Technology Data Exchange (ETDEWEB)

The behavior of major components of ash in Ekibastuz coal (quartz, cristobalite, mullite) in alkaline solutions is investigated for the determination of optimal conditions for the desiliconization of ash. It was established that the most reactive phase is crystobalite which, after a three hour treatment at 105/sup 0/, practically dissolves completely in the alkaline solution. The level of the decomposition of the quartz in the given conditions was 8.39%, and the mullite, 4.39%. An increase in the duration of the process will insignificantly increase the level of desiliconization of the ash, causing, in due order, an undesirable supplementary decomposition of mullite.

Suliaeva, H.G.; Romanov, L.G.; Shcherban, S.A.; Tazhibaeva, S.Kh.

1982-01-01

2

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.

2011-01-01

3

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

4

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...

2003-01-01

5

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

Energy Technology Data Exchange (ETDEWEB)

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 (similar to 12), were below regulatory limits of most EU countries. Arsenic concentrations in CCR transport water were < 2 {mu} g l{sup -1} whereas reductive conditions in an abandoned landfill significantly enhanced concentrations in leachates (44 {mu} g l{sup -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.

Dellantonio, A.; Fitz, W.J.; Custovic, H.; Repmann, F.; Schneider, B.U.; Grunewald, H.; Gruber, V.; Zgorelec, Z.; Zerem, N.; Carter, C.; Markovic, M.; Puschenreiter, M.; Wenzel, W.W. [University for Natural Resources & Applied Life Science, Vienna (Austria)

2008-06-15

6

Coal ash in Canada  

Energy Technology Data Exchange (ETDEWEB)

Data indicates that by 1986 over 5.0 million tonnes of ash will be produced from coal combustion by Canadian electric utilities. A study was carried out towards the development of strategies to promote the increased utilization of ash as an option to reduce the costs and environmental impacts of disposal. Critical reviews of both established and potential methods are presented. Established low value applications include structural fill, cement and concrete applications, soil and waste stabilization, clay brick and lightweight aggregate. The beneficiation of ash to recover resource components such as carbon, magnetic iron concentrate, cenospheres, and specification fillers and extenders is an alternative and desirable approach to utilization to bring ash into higher value markets. Although the technology exists for the extraction of aluminum and trace metal values from ash, this approach is not economically justified at the present time. Other potential applications for ash requiring further research and development include use in glass and ceramic products, waste water treatment, mineral wool and agriculture. The study critically addresses the technical evaluation of coal ash considered for the multiple end uses. Relevant standards, specifications and test methods are reviewed and compiled in the form of a laboratory test manual, and sample collection methods and occupational health aspects of ash utilization are considered. 1 fig.

Berry, E.E.; Hemmings, R.T.; Burns, J.S.

1983-03-01

7

Coal ash in Canada  

Energy Technology Data Exchange (ETDEWEB)

A study was carried out to develop strategies to promote the marketing of ash from coal combustion by Canadian electric utilities to reduce the costs and environmental impacts of disposal. A critical review is presented of both established and potential methods of ash utilization. Existing low value applications include structural fill, cement and concrete, soil and waste stabilization, brick, and lightweight aggregate. The beneficiation of ash to recover resource components such as carbon, magnetite, cenospheres, specification filler, alumina, ferro-silicon, and trace metals is presented as an alternative approach to bringing ash into higher market values. Other potential applications include glass and ceramic products, waste water treatment, and agriculture. The technical summaries are supported by analyses of potential market values, competing materials, and existing barriers to further utilization of a technical, institutional or marketing nature. Recommendations for improved marketing encompass ash management and quality control, promotional activities, the regulation of new combustion technologies affecting properties of ash, and environmental and occupational health aspects of ash utilization. 271 refs., 14 figs., 60 tabs.

Berry, E.E.; Hemmings, R.T.; Burns, J.S.

1983-03-01

8

Mercury concentrations in coal ash  

Energy Technology Data Exchange (ETDEWEB)

The concentrations of mercury in fly ash can be fairly well estimated from the mercury concentrations in the coal and from the particulate separation technique used. The rate of mercury emission from ash deposits is however less well known.

Svedberg, G. (Tekniska Hoegskolan, Stockholm (Sweden)). Inst. foer Kemisk Apparatteknik

1981-04-01

9

Retention of sulphur by ashes from Chinese coals  

Energy Technology Data Exchange (ETDEWEB)

During combustion, a part of the total sulphur in coal will be retained in ash as solid compounds. In present paper, retention of sulphur by ash from typical Chinese coal used for electric power generation was related with contents of alkaline elements relative to sulphur in the parent coal, and roles of alkaline elements in sulphur retention were investigated. It is confirmed that calcium plays a dominant role in the sulphur retention of laboratory-prepared ash, while the contributions of other elements are limited. From this study, it is suggested that the sulphur retention of laboratory-prepared ash can be applied to fluidized bed combustion (FBC) because the behaviour of calcium is similar to that of lime in FBC. However, the contribution of calcium to sulphur retention by ash in pulverised coal fired boiler is reduced markedly, while the roles of other alkaline elements are obviously enhanced. 21 refs., 7 figs., 1 tab.

Chang-dong Sheng; Jun Zhang; Yiqian Xu [Southeast University, Nanjing, Jiangsu (China). Department of Power Engineering

1998-12-01

10

Coal ash utilization in India  

Energy Technology Data Exchange (ETDEWEB)

This paper describes methods of coal combustion product (CCP) management successfully employed in the US and considers their potential application in India. India produces about 66 million tons per year (mty) of coal ash from the combustion of 220 mty of domestically produced coal, the average ash content being about 30--40 percent as opposed to an average ash content of less than 10 percent in the US In other words, India produces coal ash at about triple the rate of the US. Currently, 95 percent of this ash is sluiced into slurry ponds, many located near urban centers and consuming vast areas of premium land. Indian coal-fired generating capacity is expected to triple in the next ten years, which will dramatically increase ash production. Advanced coal cleaning technology may help reduce this amount, but not significantly. Currently India utilizes two percent of the CCP`s produced with the remainder being disposed of primarily in large impoundments. The US utilizes about 25 percent of its coal ash with the remainder primarily being disposed of in nearly equal amounts between dry landfills and impoundments. There is an urgent need for India to improve its ash management practice and to develop efficient and environmentally sound disposal procedures as well as high volume ash uses in ash haulback to the coalfields. In addition, utilization should include: reclamation, structural fill, flowable backfill and road base.

Michalski, S.R.; Brendel, G.F.; Gray, R.E. [GAI Consultants, Inc., Pittsburgh, PA (United States)

1998-12-31

11

Measuring ash content of coal  

International Nuclear Information System (INIS)

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

1979-10-02

12

Specialties of distributions of alkaline-earth metals in coal  

Energy Technology Data Exchange (ETDEWEB)

Four different ranks of coal have been sampled and separated into different density fractions by Float-Sink. The contents of some trace elements in each density fraction has been analyzed by ICAP. The analyzed data show that the alkaline-earth metals (Be, Sr, and Ba) have their special distributions in coal: Be and Sr may exist in the form of organic matter. Ba often has the highest content in the middle density fraction (1.4--1.5). The relative relationship between ash (or sulfur) and the trace element in a certain type of coal was obtained by using linear regression approach. Results show that there is no significant correlation between the contents of ash or sulfur and those of Be, Sr, and Ba. On the other hand, the linear regression was done among the trace elements of 17 types of coal. The results also show that there is no significant correlation between ash or sulfur and alkaline-earth metals.

Fan Jinchuan; Fan Minqiang [Shanxi Mining Inst., Taiyuan, Shanxi (China). Coal Processing and Utilization Dept.

1997-12-31

13

Physical and engineering properties of coal ash  

Energy Technology Data Exchange (ETDEWEB)

Coal ash is an oxide consisting mainly of SiO/sub 2/ and Al/sub 2/O/sub 3/. It is classified according to the site of capture as either fly ash, sinter ash or clinker ash. As regards its particle size, the first two forms are classified as silt and clinker as sand. The engineering properties of coal ash and are likewise analogous to those of silt and sand. Fly ash sinter ash both have a pozzolanic action and hence make excellent reclamation and fill materials. 4 references

Yamamoto, Y.; Tanaka, E.; Oki, R.

1983-01-01

14

COAL ASH RESOURCES RESEARCH CONSORTIUM  

Energy Technology Data Exchange (ETDEWEB)

The Coal Ash Resources Research Consortium (CARRC, pronounced ?cars?) is the core coal combustion by-product (CCB) 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 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. CARRC continued the partnership of industry partners, university researchers, and the U.S. Department of Energy (DOE) addressing needs in the CCB industry through technical research and development projects. Technology transfer also continued through distribution and presentation of the results of research activities to appropriate audiences, with emphasis on reaching government agency representatives and end users of CCBs. CARRC partners have evolved technically and have jointly developed an understanding of the layers of social, regulatory, legal, and competition issues that impact the success of CCB utilization as applies to the CCB industry in general and to individual companies. Many CARRC tasks are designed to provide information on CCB performance including environmental performance, engineering performance, favorable economics, and improved life cycle of products and projects. CARRC activities from 1993?1998 included a variety of research tasks, with primary work performed in laboratory tasks developed to answer specific questions or evaluate important fundamental properties of CCBs. The tasks summarized in this report are 1) The Demonstration of CCB Use in Small Construction Projects, 2) Application of CCSEM (computer-controlled scanning electron microscopy) for Coal Combustion By-Product Characterization, 3) Development of a Procedure to Determine Heat of Hydration for Coal Combustion By-Products, 4) Investigation of the Behavior of High-Calcium Coal Combustion By-Products, 5) Development of an Environmentally Appropriate Leaching Procedure for Coal Combustion By-Products, 6) Set Time of Fly Ash Concrete, 7) Coal Ash Properties Database (CAPD), 8) Development of a Method for Determination of Radon Hazard in CCBs, 9) Development of Standards and Specifications, 10) Assessment of Fly Ash Variability, and 11) Development of a CCB Utilization Workshop. The primary goal of CARRC is to work with industry to solve CCB-related problems and promote the environmentally safe, technically sound, and economical utilization and disposal of these highly complex materials. CARRC 1993?1998 accomplishments included: C Updating the CAPD to a user-friendly database management system, and distributing it to CARRC members. C ASTM standard preparation for a guide to using CCBs as waste stabilization agents. C Preliminary identification of specific mineral transformations resulting from fly ash hydration. C Limited determination of the effects of fly ash on the set time of concrete. C Statistical evaluation of a select set of fly ashes from several regional coal-fired power plants. C Development and presentation of a workshop on CCB utilization focused on government agency representatives and interested parties with limited CCB utilization experience. C Participation in a variety of local, national, and international technical meetings, symposia, and conferences by presenting and publishing CCB-related papers.

NONE

1998-12-01

15

Preparation and characterization of zeolites from coal ash  

Energy Technology Data Exchange (ETDEWEB)

Coal ash, which was formed as a by-product waste at coal-fired power station, was converted into zeolites by hydrothermal reaction in alkaline solution. The reaction of coal ash with sodium hydroxide at 373 K under atmospheric pressure resulted in formation of Na-P 1, Na-A type zeolite, and hydroxysodalite X-Ray microanalysis (EPMA) revealed that the zeolite zone was formed like egg white, covering the central core of fly ash particles. Comparing SEM images at various times of hydrothermal treatment, formation of coal ash zeolites was suggested to proceed by the following sequence: (1) dissolution of zeolite components from the starting fly ash particles, (2) deposit and growth of amorphous microspheres on the surface of fly ash core, and (3) crystallization of the amorphous aggregates toward Na-P 1 or Na-A type zeolite. Na-A type zeolite, which was obtained through the above sequence, gradually changed with time to afford hydroxysodalite. The zeolite was soluble in acid, and thus the weight percent of zeolite zone in fly ash zeolite could be evaluated quantitatively. The cation exchange capacity per unit weight of the acid soluble (zeolite) zone measured by NH{sub 4+} adsorption was quite close to that of synthetic zeolite.

Shigemoto, N.; Shirakami, K.; Hirano, S.; Hayashi, H. (University of Tokushima, Tokushima (Japan). Dept. of Chemical Science and Technology)

1992-05-01

16

Coal Ash Leachate Potential From Stoker Boilers.  

Science.gov (United States)

The Department of Defense (DOD) has 28 installations that use coal and produces about 120,000 short tons of ash per year. Coal ash may he classified as hazardous waste if regulatory tests show leaching of heavy metals and other elements, which would make ...

J. F. Cerbus S. Landsberger S. Larson M. J. Savoie

1994-01-01

17

Worldwide high-volume coal ash utilization  

Energy Technology Data Exchange (ETDEWEB)

The utilization of coal ash in concrete is the most extensive and widespread throughout the world, as compared to other uses of ash. However, in addition to the use in 1992 of over 39 million tons of coal ash in concrete, there were over 40 billion tons used in structural, land, or embankment fill; almost 7 million tons for pavement base course or subgrade; over 40 million tons for filler for mines, quarries or pits; almost 3 million tons for soil amendment; over 1.8 million tons for lightweight aggregate; and over 7 million tons for aerated blocks. In 1992, China had the largest production of coal ash as well as the largest utilization. Russian and the US had the second and third largest production. Russia, Germany, US, and Poland were next to China in utilization. This paper summarizes recent coal ash production and utilization in the world and presents a country-by-country survey of the high-volume users.

Manz, O.E. [Manz Associates, Alvarado, MN (United States)

1996-10-01

18

Process for removing ash from coal  

Energy Technology Data Exchange (ETDEWEB)

A process for removing ash from coal comprising the steps of transferring pulverized coal to be treated b entraining it on a stream A of anti-oxidation gas, feeding the coal laden gas into dry-type electric precipitating chamber means 2 after suitably adjusting the temperature and humidity of the gas during transport, and separating particulate ash from the coal particles by capturing the former in the chamber means 2 by virtue of difference in specific resistance between the two kind of particles, whereby highly purified coal B is obtained as entrained on the gas stream at the outlet 3 of the chamber means 2.

Kilazawa, K.; Ozaki, T.

1984-11-13

19

Mutagenicity and genotoxicity of coal fly ash water leachate.  

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 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 significant (P<0.05) concentration-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 (mum), 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. PMID:18995907

Chakraborty, Rajarshi; Mukherjee, Anita

2009-03-01

20

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

1980-04-17

 
 
 
 
21

Differences in gasification behaviors and related properties between entrained gasifier fly ash and coal char  

Energy Technology Data Exchange (ETDEWEB)

In the study, two fly ash samples from Texaco gasifiers were compared to coal char and the physical and chemical properties and reactivity of samples were investigated by scanning electron microscopy (SEM), SEM-energy-dispersive spectrometry (EDS), X-ray diffraction (XRD), N{sub 2} and CO{sub 2} adsorption method, and isothermal thermogravimetric analysis. The main results were obtained. The carbon content of gasified fly ashes exhibited 31-37%, which was less than the carbon content of 58-59% in the feed coal. The fly ashes exhibited higher Brunauer-Emmett-Teller (BET) surface area, richer meso- and micropores, more disordered carbon crystalline structure, and better CO{sub 2} gasification reactivity than coal char. Ashes in fly ashes occurred to agglomerate into larger spherical grains, while those in coal char do not agglomerate. The minerals in fly ashes, especial alkali and alkaline-earth metals, had a catalytic effect on gasification reactivity of fly ash carbon. In the low-temperature range, the gasification process of fly ashes is mainly in chemical control, while in the high-temperature range, it is mainly in gas diffusion control, which was similar to coal char. In addition, the carbon in fly ashes was partially gasified and activated by water vapor and exhibited higher BET surface area and better gasification activity. Consequently, the fact that these carbons in fly ashes from entrained flow gasifiers are reclaimed and reused will be considered to be feasible. 15 refs., 7 figs., 5 tabs.

Jing Gu; Shiyong Wu; Youqing Wu; Ye Li; Jinsheng Gao [East China University of Science and Technology, Shanghai (China). Department of Chemical Engineering for Energy Resources and Key Laboratory of Coal Gasification of Ministry of Education

2008-11-15

22

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

23

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

24

Flotation of resinite from high ash coal  

Energy Technology Data Exchange (ETDEWEB)

The author investigated selective resinite flotation of high ash coal under different conditions. It was found that both the grade and recovery of the obtained resinite depended on the type of frother used. By wet screening, grinding and pH control, the grade reached 80% with a recovery of 70%.

Atia, A.A. [Menoufia University, Menoufia (Egypt). Dept. of Chemistry

1999-02-01

25

Phase relationship in coal ash corrosion products  

Energy Technology Data Exchange (ETDEWEB)

The corrosion of heat transfer surfaces in coal-fired utility boilers is a major concern to the efficient operation of these units. Despite the importance of the corrosion there has been limited research on the relationship between the ash components on the tube surface and the interactions and reactions between the various components and the steel surface. Mechanisms such as molten phase corrosion, sulfidation, and high temperature oxidation have been identified as leading to extensive wastage oftube metal. However, while the corrosion process can be identified using techniques such as metallography and x-ray diffraction there is limited insight into the role ofthe coal mineralogy and ash deposits on the surface in the corrosion process. This paper describes research into the formation of molten or sernimolten phases within ash deposits which are associated with corrosion of superheater and reheater fireside surfaces. For example, the phases potassium pyrosulfate (K{sub 2}S{sub 2}O{sub 7}) and potassium aluminum sulfate (K{sub 2}Al{sub 2}SO{sub 7}) have been determined by x-ray diffraction to be present in deposits where fireside corrosion has occurred. However, both these phases are not directly derived from coal minerals or the common matrix observed in ash deposits. The examination of the reactions and interactions within deposits which result in the formation of these and other phases associated with corrosion will be discussed in the paper.

Kalmanovitch, D. [DB Riley, Inc., Worcester, MA (United States)

1996-12-31

26

Evaluation of Technology for the Recovery of Metallurgical-Grade Alumina From Coal Ash.  

Science.gov (United States)

The Bureau of Mines has reviewed the literature related to the recovery of Al2O3 (alumina) from coal ash. A small amount of unpublished data is also reported. Of the processes studied, the alkaline-sinter process is the most promising from a technical sta...

J. A. Eisele D. J. Bauer

1979-01-01

27

Studies of the specific gravity of some Indian coal ashes  

Energy Technology Data Exchange (ETDEWEB)

One of the major problems faced by coal based thermal power stations is handling and disposal of ash. The generally low specific gravity of fly ash resulting in low unit weight as compared to soils is an attractive property for its use in geotechnical applications. In general, specific gravity of coal ash lies around 2.0 but can vary to a large extent (1.6 to 3.1). The variation of specific gravity of coal ash is due to the combination of various factors like gradation, particle shape, and chemical composition. The specific gravity of three Indian coal ashes was investigated.

Pandian, N.S.; Rajasekhar, C.; Sridharan, A. [Indian Institute of Science, Bangalore (India)

1998-09-01

28

Norm in coal, fly ash and cement  

International Nuclear Information System (INIS)

Coal is technologically important materials being used for power generation and its cinder (fly ash) is used in manufacturing of bricks, sheets, cement, land filling etc. 222Rn (radon) and its daughters are the most important radioactive and potentially hazardous elements, which are released in the environment from the naturally occurring radioactive material (NORM) present in coal, fly ash and cement. Thus it is very important to carry out radioactivity measurements in coal, fly ash and cement from the health and hygiene point of view. Samples of coal and fly ash from different thermal power stations in northern India and various fly ash using establishments and commercially available cement samples (O.P.C. and P.P.C.) were collected and analyzed for radon concentration and exhalation rates. For the measurements, alpha sensitive LR-115 type II plastic track detectors were used. The radon concentration varied from 147 Bq/m3 to 443 Bq/m3, the radium concentration varied from 1.5 to 4.5 Bq/kg and radon exhalation rate varied from 11.8 mBq.kg-1.h-1 to 35.7 mBq.kg-1.h-1 for mass exhalation rate and from 104.5 mBq.m-2.h-1 to 314.8 mBq.m-2.h-1 for surface exhalation rate in coal samples. The radon concentration varied from 214 Bq/m3 to 590 Bq/m3, the radium concentration varied from 1.0 to 2.7 Bq/kg and radon exhalation rate varied from 7.8 mBq.kg-1.h-1 to 21.6 mBq.kg-1.h-1 for mass exhalation rate and from 138 mBq m-2h-1 to 380.6 mBq.m-2.h-1 for surface exhalation rate in fly ash samples. The radon concentration varied from 157.62 Bq/m3 to 1810.48 Bq/m3, the radium concentration varied from 0.76 Bq/kg to 8.73 Bq/kg and radon exhalation rate varied from 6.07 mBq.kg-1.hr-1 to 69.81 mBq.kg-1.hr-1 for mass exhalation rate and from 107.10 mBq.m-2.hr-1 to 1230.21 mBq.m-2.hr-1 for surface exhalation rate in different cement samples. The values were found higher in P.P.C. samples than in O.P.C. samples. (authors)

2006-05-15

29

Flotation of resinite from high ash coal  

Energy Technology Data Exchange (ETDEWEB)

Selective resinite flotation with frothers was studied for high ash coal sample under different conditions. It was found that both the grade and the recovery of the obtained resinite depend on the type of frother used. The presence of fines reduced the resinite grade significantly. The grade was improved to 80% with a recovery of 70% through wet screening, grinding and pH control. Contact angle and zeta potential measurements were used to characterize the sample surfaces.

Atia, A.A. [Menofeya University, Menofeya (Egypt). Dept. of Chemistry

1999-01-01

30

Study of ash deposition during coal combustion under oxyfuel conditions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents a comparative study on ash deposition of two selected coals, Russian coal and lignite, under oxyfuel (O?/CO?) and air combustion conditions. The comparison is based on experimental results and subsequent evaluation of the data and observed trends. Deposited as well as remaining filter ash (fine ash) samples were subjected to XRD and ICP analyses in order to study the chemical composition and mineral transformations undergone in the ash under the combustion ...

Fryda, L.; Sobrino, Celia; Glazer, M.; Bertrand, C.; Cieplik, M.

2012-01-01

31

Coaling and ash removal plants in Heyden power station  

Energy Technology Data Exchange (ETDEWEB)

In December 1996 PreussenElektra AG Hanover appointed FAM Foerderanlagen Magdeburg to lead a consortium for the coaling and ash removal plants of the 910 MV coal-fired power station at Heyden. Joh. Moeller Hamburg Engineering GmbH was won as partner in the consortium for the pneumatic ash transportation and Binder, Austria, for the mechanical equipment for the seasonal ash silo. The complete scope of delivery and service comprised the engineering, equipment reconstruction and adaptation, delivery, erection and commissioning of the complete equipment for a coaling plant and the electrostatic ash removal and the coarse ash removal equipment. (orig.)

Stache, B. [FAM Foerderanlagen Magdeburg, Magdeburg (Germany)

1999-09-01

32

Physical and biological studies of coal and oil fly ash.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Studies were performed to compare the physical and chemical characteristics and the in vitro macrophage cytotoxicity of oil and coal fly ash. Sampling methodology was developed to collect size-fractionated particulate matter from the smokestack of either a coal-fired or an oil-fired power plant. Morphological studies demonstrated particle heterogeneity, although most coal fly ash particles appeared to be spherical. Oil fly ash contained two major morphologies; nonopaque amorphous particles an...

1983-01-01

33

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1995-08-01

34

Evaluation of engineering properties for the use of leached brown coal ash in soil covers.  

Science.gov (United States)

The need to engineer cover systems for the successful rehabilitation or remediation of a wide variety of solid wastes is increasing. Some common applications include landfills, hazardous waste repositories, or mine tailings dams and waste rock/overburden dumps. The brown coal industry of the Latrobe Valley region of Victoria, Australia, produces significant quantities of coal ash and overburden annually. There are some site-specific acid mine drainage (AMD) issues associated with overburden material. This needs to be addressed both during the operational phase of a project and during rehabilitation. An innovative approach was taken to investigate the potential to use leached brown coal ash in engineered soil covers on this overburden dump. The basis for this is two-fold: first, the ash has favourable physical characteristics for use in cover systems (such as high storage capacity/porosity, moderately low permeability, and an ability to act as a capillary break layer generating minimal leachate or seepage); and second, the leachate from the ash is mildly alkaline (which can help to mitigate and reduce the risk of AMD). This paper will review the engineering issues involved in using leached brown coal ash in designing soil covers for potentially acid-forming overburden dumps. It presents the results of laboratory work investigating the technical feasibility of using leached brown coal ash in engineered solid waste cover systems. PMID:16621267

Mudd, Gavin M; Chakrabarti, Srijib; Kodikara, Jayantha

2007-01-31

35

Phase relationships in coal ash corrosion products  

Energy Technology Data Exchange (ETDEWEB)

The corrosion of heat transfer surfaces in coal-fired utility boilers is a major concern to the efficient operation of these units. Despite the importance of the corrosion there has been limited research on the relationship between the ash components on the tube surface and the interactions and reactions between the various components and the steel surface. Mechanisms such as molten phase corrosion, sulfidation, and high temperature oxidation have been identified as leading to extensive wastage of tube metal. This paper describes research into the formation of molten or semimolten phases within ash deposits which are associated with corrosion of superheater and reheater fireside surfaces. For example, the phases potassium pyrosulfate (K{sub 2}S{sub 2}O{sub 7}) and potassium aluminum sulfate (K{sub 2}Al{sub 2}SO{sub 7}) have been determined by x-ray diffraction to be present in deposits where fireside corrosion has occurred. However, both these phases are not directly derived from coal minerals or the common matrix observed in ash deposits. The examination of the reactions and interactions within deposits which result a the formation of these and other phases associated with corrosion will be discussed in the paper.

Kalmanovitch, D. [Consultant Materials Engineering, Worcester, MA (United States)

1996-10-01

36

Utility management issues in improving coal ash utilization  

Energy Technology Data Exchange (ETDEWEB)

Duke Power Company started monitoring ash utilization in 1988. From 1988 through 1992, Duke Power`s ash utilization percentage varied from 19% to 32%. In 1993 Duke Power used a commodity team approach to study the nature of ash utilization and disposal and made recommendations to improve the beneficial use of coal ash produced on the Duke system. One of the recommendations of the coal ash commodity team was to establish an ash management group specifically chartered to improve coal ash utilization. The author was selected to manage the ash management group on October 1, 1993. This paper identifies and discusses some of the key management issues addressed by the group in raising the utilization rate from 27.3% in 1993 to 56.6% in 1994.

Nerison, J.P. [Duke Power Co., Charlotte, NC (United States)

1995-09-01

37

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

38

Electrostatic process key to successful coal-ash recycling  

Energy Technology Data Exchange (ETDEWEB)

The operation of a coal-ash recycling facility is briefly outlined. The facility uses an electrostatic separation process to remove carbon from ash. The resulting product is a low carbon ash that can substitute for cement. Plant operation and facility expansion plans are highlighted in the article.

Hansen, T.

1996-09-01

39

Microstructural changes in coal during low temperature ashing  

Energy Technology Data Exchange (ETDEWEB)

Samples of two US coals were oxidised for 72 hours in a low temperature asher. Scanning electron microscopy and automated electron microprobe analysis were employed to observe the mineralogical changes produced in the coal by the ashing process. It was found that the microstructure of the low temperature ash was strongly influenced by the mineral matter which was originally chemically-bound in the organic matrix of the starting coal. The partial oxidation of pyrite during the ashing was also observed. The results reveal some of the physical mechanisms involved in the low temperature ashing process. 21 references.

Allen, R.M.; Carling, R.W.; VanderSande, J.B.

1986-03-01

40

The recycling of the coal fly ash in glass production.  

Science.gov (United States)

The recycling of fly ash obtained from the combustion of coal in thermal power plant has been studied. Coal fly ash was vitrified by melting at 1773 K for 5 hours without any additives. The properties of glasses produced from coal fly ash were investigated by means of Differential Thermal Analysis (DTA), X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) techniques. DTA study indicated that there was only one endothermic peak at 1003 K corresponding to the glass transition temperature. XRD analysis showed the amorphous state of the glass sample produced from coal fly ash. SEM investigations revealed that the coal fly ash based glass sample had smooth surface. The mechanical, physical and chemical properties of the glass sample were also determined. Recycling of coal fly ash by using vitrification technique resulted to a glass material that had good mechanical, physical and chemical properties. Toxicity characteristic leaching procedure (TCLP) results showed that the heavy metals of Pb, Cr, Zn and Mn were successfully immobilized into the glass. It can be said that glass sample obtained by the recycling of coal fly ash can be taken as a non-hazardous material. Overall, results indicated that the vitrification technique is an effective way for the stabilization and recycling of coal fly ash. PMID:16849136

Erol, Melek Mumine; Küçükbayrak, Sadriye; Ersoy-Meriçboyu, Ay?egül

2006-01-01

 
 
 
 
41

Process to remove ash components from high-ash coals. Verfahren zum Entzug von Aschebestandteilen aus aschereichen Kohlen  

Energy Technology Data Exchange (ETDEWEB)

Ash components are removed from coals, particularly high-ash bituminous and brown coals by grinding the coal, suspending it in aqueous mediums and dissolving the ashes at elevated temperature and pressure by stirring. Subsequently the coal is separated from the aqueous phase. Alkalis can be added to the dissolving water. (KHH).

Tippmer, K.

1982-11-11

42

The potential of biological sludge amended combustion coal ash residues as artificial plant growth media : a laboratory column study to assess the influence of weathering on elemental release  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Sasol biological sludge, coal fine and gasification ash were the three waste streams involved in this study. The main concern is that on their own they are not suitable as growth mediums, the ash is alkaline (pH>12) with high salinity (total dissolved solids of 8000 mg ?-1). Fine ash is microporous (particle size diameter <250 ?m) and forms cemented layers that can restrict root growth while, gasification ash in macroporous (most particle size diameter ranged between 1 and 75 mm...

2012-01-01

43

Determining the ash content of coal flotation tailings using an MPOF optical ash meter  

Energy Technology Data Exchange (ETDEWEB)

The block layout, a description of the design and principles of operation of an automatic optical, continuous action MPOF type ash meter are presented. The difference in the optical properties of coal and rock is used in the ash meter. The identification of the ash content is conducted on the basis of the spectral characteristics of reflection of a finely dispersed aqueous coal and rock suspension.

Sikora, T.; Sliwa, J.

1982-01-01

44

Evaluation of sintering phenomenon of ashes of some Indian coals  

Energy Technology Data Exchange (ETDEWEB)

Sintering temperatures of low- and high-temperature ashes from nine coals were measured by dilatometry of pellets, and crushing strengths of the sintered pellets were determined. The results suggested that the greater the difference between the sintering temperatures of the two types of ash, the greater was the susceptibility of the ash to form sintered deposits below the fusion temperature in p.f. boilers. Ash compositions and fusion temperatures were also determined.

Mukherjee, S.N. [and others

1993-01-01

45

Feasibility of using coal ash residues as co-composting materials for sewage sludge  

Energy Technology Data Exchange (ETDEWEB)

Alkaline coal ash residues produced from a coal-fired power plant were co-composted with sewage sludge to evaluate its effect on heavy metal availability and the biological process of composting. Coal fly ash (FA) and lagoon ash (LA) were mixed with dewatered sludge at 0, 10 and 25% w/w, and the mixtures were composted for 100 days in laboratory batch reactors. The changes in pH electrical conductivity (EC), CO{sub 2} production, microbial population, soluble and extractable heavy metal contents were measured during the compositing period. Following an initial increase, pH started to decrease from day 7 onward till the end of the composting period for all treatments. Sludge with coal fly ash amendment had a higher pH and EC than those of the control and LA-sludge composts. Increasing fly ash amendment levels resulted in a significant reduction in DTPA-extractable Cd, Cu, Zn, Mn and Pb contents of the FA-sludge composts while the reduction was less obvious in the LA-sludge composts. No significant difference in CO{sub 2} production and the number of thermophilic bacteria were noted for all treatments except for 25% FA-sludge compost which had a reduced thermophilic bacterial growth and CO{sub 2} production. The inhibition which was possibly due to the high FH of coal fly ash, decreased with an increase in composting time. It can be concluded that the co-compositing of coal ash residues with sewage sludge was able to reduce the availability of metals but did not exert a significant inhibition on the biological process of composting, except for 25% FA-sludge compost.

Wong, J.W.C.; Fang, M.; Li, G.X.; Wong, M.H. [Hong Kong Baptist University, Kowloon (Hong Kong). Dept. of Biology

1997-05-01

46

Extraction of alumina from anthracite coal waste ash  

Energy Technology Data Exchange (ETDEWEB)

Ash samples from an anthracite coal waste, fired at 788 to 899/sup 0/C in a fluidized bed combustor, were studied for alumina extraction and other process characteristics by using a hydrothermal alkaline digestion process with lime. The independent variables included digestion temperature, digestion time, liquor caustic concentration, target alumina concentration in the liquor after digestion (or ash to liquor ratio) and molar ratio of total lime to total silica in the solid feed materials. Experiments in bench scale nickel reactors were conducted according to a 2 fractional factorial design. The resultant data were studied through a regression analysis. The statistical analysis indicated that alumina extraction, with the highest at 96%, is increased largely by increasing digestion temperature or liquor caustic concentration or by decreasing target alumina concentration. Within the range of variables investigated, digestion time and molar ratio of total CaO to total SiO/sub 2/ have no significant effects on any of the properties examined. The presence of Na/sub 2/O-2CaO-2SiO/sub 2/-H/sub 2/O in the digest mud according to the desired chemistry has been confirmed by chemical and x-ray diffraction analyses. Alumina was not recovered under less favorable conditions. A block flow diagram is proposed for the digestion and subsequent process steps based on the bench data and past experience with high-silica ores.

Hsieh, H.P.

1982-01-01

47

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2013-01-01

48

Systematic errors in neutron methods of monitoring ash in coal  

International Nuclear Information System (INIS)

Nuclear physics methods of monitoring ash in coal are widely used, in particular neutron methods based on recording the gamma-rays arising from reaction with elements in coal. Several possible methods of determining ash content are discussed. The main factors influencing the accuracy in measuring ash contents by nuclear-physics methods are the density, water content, and the variable elemental composition of the ash. To determine the systematic error it is necessary to know the sensitivity to the ash content and to the influencing factors, the factor variances, and the correlation co-efficients between the factors and the ash content. The optimum method of ash determination should be selected for each particular case to minimize the systematic error while providing the required speed and representativeness

1986-01-01

49

Design obtainment and properties of glasses and glass-ceramics from coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

Glasses and glass-ceramics were obtained by mixing up to 50 wt% of Italian or Spanish coal fly ash with other wastes (glass cullet and float dolomite). The behaviour of 10 compositions was investigated by thermal (DTA) and mineralogical (XRD) analysis, microstructural (SEM) characterization, mechanical and chemical measurements. It was verified that the contribution of the alkaline-earth elements in the original composition is fundamental to easily obtain glass-ceramics with a fine microstructure which improves the mechanical properties. Otherwise, with a small addition of fly ash and without dolomite, very stable glassy materials were obtained that did not exhibit any visible etching either in water or in acid media. Therefore, the combined vitrification/devitrification technique is a suitable methodology for the recycling and exploitation of coal fly ash. 12 refs., 5 figs., 4 tabs.

Barbieri, L.; Lancellotti, I.; Manfredini, T.; Queralt, I.; Rincon, J.M.; Romero, M. [University of Modena, Modena (Italy). Dept. of Chemistry

1999-01-01

50

Synthesis of zeolite from coal fly ashes with different silica-alumina composition  

Energy Technology Data Exchange (ETDEWEB)

Coal fly ashes can be converted into zeolites by hydrothermal alkaline treatment. This study focuses on the effect of Si/Al molar ratio of the fly ash source on the type of formed zeolite, which also is affected by the alkaline condition. The fly ashes were mixed with an aqueous NaOH solution and hydrothermally treated at about 100{degree}C. Zeolite Na-P1 and/or hydroxy-sodalite appeared after the treatment. Zeolite Na-P1 predominantly formed from silica-rich fly ash at a low-NaOH concentration. The cation exchange capacity of the product with a large content of zeolite Na-P1 reached a value of 300 meq/100 g. The type of the product was controlled by addition of aerosil silica or alumina. It was found that silica addition effectively enhances the formation of zeolite Na-P1, even at a high-NaOH concentration. These results were discussed on the basis of a formation mechanism of zeolite from coal fly ash through dissolution-precipitation process. 10 refs., 6 figs., 1 tab.

Miki Inada; Yukari Eguchi; Naoya Enomoto; Junichi Hojo [Kyushu University, Fukuoka (Japan). Department of Chemistry and Biochemistry, Graduate School of Engineering

2005-02-01

51

Ignition of ash-coal particles and aerosols  

Energy Technology Data Exchange (ETDEWEB)

The ignition of individual coal particles of different ash content (4.5-72%) has been investigated experimentally and theoretically as well as the ignition of aerosols of such particles. It has been determined that depending on the ash content in coal and the ignition-ash fusion temperatures relation, there are different mechanisms of ignition (thermal or thermal-kinetic), which are similar to the ignition of metal particles with porous or continuous oxide film. The comparison of the experimental and calculated values of the coal particles aerosol ignition temperature is given. 6 refs., 2 figs.

Klyachko, L.A.; Vovchuk, Y.I.; Kiro, S.A.; Zolotko, A.N. [Central Institute of Aviation Motors, Moscow (Russian Federation)

1995-12-31

52

Pozzolanic properties of pulverized coal combustion bottom ash  

Energy Technology Data Exchange (ETDEWEB)

The pozzolanic properties of a coal combustion bottom ash were investigated. Plain pastes containing equal amounts of calcium hydroxide and bottom ash were prepared and analyzed at different ages for their strength and the calcium hydroxide consumption. At early ages, bottom ash does not react with calcium hydroxide. Its pozzolanic reaction proceeds slowly and accelerates gradually to become very interesting after 28 days and especially after 90 days. The strength activity indexes measured on mortars are sufficiently important to allow the use of bottom ash in concrete. When ground for 6 h in a laboratory ball mill, the 28-day strength activity index of bottom ash is increased by 27%.

Cheriaf, M.; Rocha, J.C.; Pera, J.

1999-09-01

53

Extraction of high sulfur and high ash power coal  

Energy Technology Data Exchange (ETDEWEB)

Power coal from the Janina mine with sulfur content from 0.86 to 2.30% and ash content from 9.64% to 24.01% and from the Siersza coal mine with sulfur content of 1.85% and ash content of 16.02% was extracted using hydrogenated anthracene oil as a solvent. Extraction conditions were as follows: temperature 400 C, extraction time 1 h, pressure from 8.2 to 9.1 MPa, relation of coal to solvent 1 to 2. The paper evaluates results of investigations carried out on a laboratory scale. Solvent extraction was an efficient method for coal desulfurization and reducing its ash content. Sulfur content was reduced to below 0.8% and ash content declined to below 0.3%. Extract yields ranged from 56 to 58% in the case of coal from the Janina mine and 47.4% in the case of coal from the Siersza mine. Conversion degree amounted to 74% in the case of coal from the Siersza mine and ranged from 78 to 81% in the case of coal from the Janina mine. Ash and sulfur content in coal did not influence conversion degree, yields or extract properties. 6 references.

Rusin, E.; Potyka, W.; Rusin, A.

1984-05-01

54

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)

2006-09-01

55

Reduction of ash deposition in pulverized coal fired boilers  

Energy Technology Data Exchange (ETDEWEB)

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

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

2013-07-01

56

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)

1980-02-08

57

Coal ash: America's undiscovered resource  

Energy Technology Data Exchange (ETDEWEB)

The US has over 800 million tons of coal ash stockpiled and available for aboveground mining. Increased use of coal will add 100 million tons a year. Fly ash, which represents about 75% of the total, is the most versatile in its range of applications. These include the manufacture of cement, brick, roofing felt, mineral-wool insulation, highway subgrading, etc. Bottom ash, or boiler slag, is useful for sand blasting, water treatment filtration, road deicing, cold mix asphalt, and structural fill. Demonstrations using ash for these and other uses have been impressive. Using coal ash will not only eliminate stockpiling problems, but will preserve other natural resources and create high-value and high-quality products.

Anthony, T.

1984-11-08

58

Use of lignite fly ash as an additive in alkaline stabilisation and pasteurisation of wastewater sludge  

Energy Technology Data Exchange (ETDEWEB)

The possibility of using lignite fly ash in low doses for reducing the pathogen levels in wastewater sludge was investigated. The results showed that using fly ash alone in doses of 40%,80% and 120% (on a dry weight basis), did not produce an alkaline environment for an efficient removal of pathogens. However, using fly ash in conjunction with the minimum amount of quicklime may act as an effective way of fecal coliform removal in both alkaline stabilisation and pasteurisation processes. It was shown that using fly ash in doses of 80% and 120% in alkaline stabilisation and pasteurisation processes prevented the pH decays and regrowth of pathogens during 60 days of storage period. The results of the study confirmed that alkaline pasteurisation process produces a product which is more resistant to pH decays and regrowth of fecal coliforms compared to that of alkaline stabilisation. Consequently, the overall results of this study indicated that the minimum lime and fly ash dosages required to generate a Class B biosolid were 10-15% and 80%, respectively. On the other hand, heating sludge to 50{degree}C prior to the addition of 10-15% quicklime and 80% fly ash followed by further heating to 70{degree}C and then sustaining at this temperature for 30 minutes were sufficient to generate a Class A biosolid.

Kocaer, F.O.; Alkan, U.; Baskaya, H.S. [Uludag University, Bursa (Turkey). Faculty of Engineering & Architecture

2003-10-01

59

Assessing the environmental impact of coal ash disposal  

Energy Technology Data Exchange (ETDEWEB)

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.

Mudd, G.M.; Kodikara, J. [Victoria University of Technology, Footscray, VIC (Australia); McKinley, T. [Geo-Eng Australia Pty. Ltd., Morwell, VIC (Australia)

1997-04-01

60

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

 
 
 
 
61

Device for the ash content determination in coal samples  

International Nuclear Information System (INIS)

The invention is concerned with a device for the ash content determination of selected ash components in coal samples by means of the neutron activation analysis. It allows an activation of samples up to some hundred grams and a fast sample changing with an always sufficient shielding. The device can easily be moved and is independent of an accelerator

1985-08-06

62

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

63

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

International Nuclear Information System (INIS)

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

2003-06-01

64

Improving phosphate removal of sand infiltration system using alkaline fly ash.  

Science.gov (United States)

Septic tank effluent is customarily disposed of by soil infiltration. Coarse, sandy soil such as those found in Perth, Western Australia, exhibit low attenuation capabilities for phosphate (PO4(3-)) during effluent infiltration. Amendment of such soil with different amounts of alkaline precipitator and lagoon fly ashes was investigated as a means of reducing phosphorus (P) leakage to ground water. Alkaline precipitator fly ash possessed the highest P sorption capacity in terms of its Langmuir and Freundlich isotherm parameters during initial batch tests. The test materials were repeatedly contacted with fresh PO4(3-) solutions over 90 contacting cycles to gain a better indication of long-term P sorption capability. Again, precipitator fly ash exhibited higher P sorption capacity than lagoon fly ash and Spearwood sand. Column studies assessed the influence of various application rates of alkaline precipitator and lagoon fly ashes on the P removal of septic tank effluent. Septic tank effluent was applied at the rate of 4 cm/day to the column for 12 weeks. Concentrations of P were monitored in the column effluent. All the fly ash columns were more efficient in reducing P migration compared to the sand column. Increased levels of fly ash in the soil columns resulted in increased P attenuation. Lagoon fly ash was inferior to precipitator fly ash for P removal; high application rates of fly ash caused clogging of the infiltration bed apparently due to their lower permeability. It is reasoned that 5-15% precipitator fly ash, and less than 30% lagoon fly ash could be added to coarse sands to produce an infiltration bed, which would result in a better quality effluent than can be obtained with untreated sand alone. PMID:10819207

Cheung, K C; Venkitachalam, T H

2000-07-01

65

Coal fly ash as an amendment to container substrate for Spathiphyllum production  

Energy Technology Data Exchange (ETDEWEB)

Coal fly ash, possessing alkalinity and containing some essential mineral elements, could be an alternative to lime amendment and a nutrient source of container substrates for ornamental plant growth. This study examined physiochemical properties of three fly ashes collected from Florida, Michigan, and North Carolina and container substrates formulated by incorporating commercial dolomite and the three fly ashes, respectively into a soilless basal substrate. The basal, dolomite- and fly ash-amended substrates were used to grow peace lily (Spathiphyllum Schott 'Ty's Pride'), a popular ornamental foliage plant, in 15-cm diameter containers in a shaded greenhouse. Electrical conductivities and pH of the substrates were monitored monthly. Plant canopy heights and widths, shoot fresh and dry weights were recorded five months after transplanting, and tissue nutrient contents were measured. This study demonstrates that the three fly ashes can be alternatives to commercial dolomites used as amendments to soilless substrates for ornamental plant production. Utilization of fly ashes as container substrate amendments should represent a new market for the beneficial use of coal combustion byproducts.

Chen, J.J.; Li, Y.C. [University of Florida, Apopka, FL (United States). Dept. of Environmental Horticulture

2006-10-15

66

Determination of ash, moisture and specific energy of coal  

International Nuclear Information System (INIS)

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

1984-12-04

67

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

68

Indices for coal desulfurization and de-ashing processes  

Energy Technology Data Exchange (ETDEWEB)

Coal beneficiation processes are evaluated based on performance indices. Adequate definitions of these indices are very important because the process operating parameters are adjusted by a control system according to the required values of the indices. This paper discusses the following performance indices for physical processes of coal desulfurization and demineralization: coal matter recovery, total sulfur rejection, ash rejection, inorganic sulfur rejection, unit index of sulfur rejection, unit index of ash rejection, joint unit index of sulfur and ash rejection, and overall index of coal upgrading. The deficiencies of the existing definitions of these indices are pointed out and new, more adequate indices are proposed. The advantages of the proposed indices are demonstrated by applying them to the assessment of selective agglomeration of coal, using the extensive experimental database for this process. 4 refs., 1 fig., 4 tabs.

Petela, R.; Petela, G. [Technology Scientific Ltd., Calgary, AB (Canada)

1996-09-01

69

Mineralogy and geochemistry of Greek and Chinese coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

In this paper the mineralogy and geochemistry of Greek and Chinese coal fly ash are examined. Annual production of fly ash in China is around 160 Mt while in Greece lignite fly ash accounts around 10 Mt. Even though the mineralogical and chemical composition of the fly ashes coming from these two countries differs, there are common questions on the utilization of this material. The variation of the Greek fly ash chemical composition, from Ca-poor to Ca-rich fly ash, has resulted to applications such as dam construction, use in cement and possibly in concrete and road construction. The Chinese fly ash, which is rich in mullite, is broadly applied for brick making. 13 refs., 6 figs., 3 tabs.

Nikolaos K. Koukouzas; Rongshu Zeng; Vassilis Perdikatsis; Wendong Xu; Emmanuel K. Kakaras [Institute for Solid Fuels Technology and Applications, Attica Technology Park, Athens (Greece). Centre for Research and Technology Hellas

2006-11-15

70

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2001-03-01

71

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

72

Thermal conductivity of coal ashes and slags  

Energy Technology Data Exchange (ETDEWEB)

Generally, heat in solids is conducted by the free electrons in metals and alloys at low temperatures, by thermal vibrations of atoms that are observed in the stoichiometric dielectrics, by the free electrons and holes as well as lattice vibrations at the sufficiently high temperatures recorded in semiconductors, and also by ions in amorphous materials at high temperatures. In our case, the linear variations of both thermal and electrical conductivities suggest also that ionization of point defects related to nonstoichiometry, impurities, and dopants plays some role in the thermal conductivity at intermediate and high temperatures. They create free carriers, such as electrons and holes, with concentrations that increase with temperature. The magnitude of this electronic component of thermal conductivity is very low, since [sigma]/k is about 10[sup [minus]6]. Also, there is reason to expect the existence of electrically charged ceramic particles in a liquid-phase sintering medium that may introduce free charges. The ionic component in heat transfer, related to the diffusion of alkali ions, does not play any major role in this range of temperature and can be neglected. This component may take place above some critical temperature, across the surface, or through the volume of the material and is strongly dependent on the glass structure. Figure 7 shows the effect of porosity on the thermal conductivity of Beulah coal ash. Thermal conductivity decreases with the increase of porosity.

Steadman, E.N.; Benson, S.A.; Nowok, J.W.

1992-01-01

73

Thermal conductivity of coal ashes and slags  

Energy Technology Data Exchange (ETDEWEB)

Generally, heat in solids is conducted by the free electrons in metals and alloys at low temperatures, by thermal vibrations of atoms that are observed in the stoichiometric dielectrics, by the free electrons and holes as well as lattice vibrations at the sufficiently high temperatures recorded in semiconductors, and also by ions in amorphous materials at high temperatures. In our case, the linear variations of both thermal and electrical conductivities suggest also that ionization of point defects related to nonstoichiometry, impurities, and dopants plays some role in the thermal conductivity at intermediate and high temperatures. They create free carriers, such as electrons and holes, with concentrations that increase with temperature. The magnitude of this electronic component of thermal conductivity is very low, since {sigma}/k is about 10{sup {minus}6}. Also, there is reason to expect the existence of electrically charged ceramic particles in a liquid-phase sintering medium that may introduce free charges. The ionic component in heat transfer, related to the diffusion of alkali ions, does not play any major role in this range of temperature and can be neglected. This component may take place above some critical temperature, across the surface, or through the volume of the material and is strongly dependent on the glass structure. Figure 7 shows the effect of porosity on the thermal conductivity of Beulah coal ash. Thermal conductivity decreases with the increase of porosity.

Steadman, E.N.; Benson, S.A.; Nowok, J.W.

1992-12-01

74

Water-barrier materials incorporating coal ash  

Energy Technology Data Exchange (ETDEWEB)

The properties are reported of hardening mixtures of 1) fly ash + cement + gypsum and 2) sand + fly ash + cement-based hardeners, and the use of such mixtures at the Sakata power station. The report focusses on land reclamation techniques and on fly ash + hardener mixtures for water-impermeable layers.

Ueda, C.; Baba, S.

1985-01-01

75

MERCURY CAPTURE ON COAL COMBUSTION FLY ASH. (R827649)  

Science.gov (United States)

A study was performed at the Energy and Environmental Research Center (EERC) to test the hypotheses that (1) different carbon types contained in coal combustion fly ash have variable sorption capabilities relative to mercury and (2) the inorganic fraction of coal combustion fl...

76

Enhanced HCl sorption with hydrated coal burnt ash  

Energy Technology Data Exchange (ETDEWEB)

The applicability of hydrated coal burnt ashes as dry gas sorbents for enhanced HCl removal was experimentally studied. In this work, three kinds of coal burnt ash discharged from fluidized bed coal combustion were hydrated with deionized water and with solutions of alcohols such as methanol, ethanol, diethylene glycol, propylene glycol and glycerin at 273 to 353 K. The hydrated sorbent was tested for HCl removal in a fixed bed reactor under simulated conditions of flue gas capture for a municipal waste incinerator (473 K, 1,000 ppmv HCl). It was found that the improvement of HCl sorption was large with higher CaO content in the hydrated coal burnt ash. The increase in the HCl sorption capacity of coal burnt ash increased with hydration temperature. Maximum HCl sorption as obtained with hydration using glycerin. XRD results showed the generation of Ca(OH){sub 2} with higher crystallinity after hydration. Hydration of coal ash caused remarkable increase in surface area of pore, between 0.001 {mu}m and 0.01 {mu}m, which played a significant role in high HCl sorption.

Hirabayashi, D.; Saito, Y.; Ozawa, S.; Matsuda, H.; Tanahashi, N. [Nagoya University, Nagoya (Japan)

2002-11-01

77

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

78

Salinity of ashes in the Berezovsk coal seam  

Energy Technology Data Exchange (ETDEWEB)

The Vostsibuglerazvedka investigated properties of the Berezovsk brown coal seam in the Kansk-Achinsk basin. Investigations were based on a large number of drill cores. Brown coal classified as 1B and 2B coal consists of 80 to 85% vitrinite with reflectivity coefficient ranging from 0.30 to 0.40. The average ash content ranges from 4.2% to 5.8% (close to the seam floor or roof ash content is 1 to 3% higher). Content of the following oxides in the ashes was analyzed: calcium oxides, magnesium oxides, silica, aluminium oxides, iron oxides, titanium oxides, manganese oxides, phosphorus oxides, sulfur oxides, sodium oxides and potassium oxides. Effects of ash content, depth and position of a coal layer in the seam on content of individual oxides were analyzed. Equations which describe correlations of oxide content with depth were derived. Analyses showed that mineral content in coal (with a high moisture content from 35 to 40%) has been increased among others by a high mineral content in water (so-called secondary mineralization). Use of hydraulic mining and hydraulic coal transport would reduce mineral content in coal (by dilution and separation).

Mingaleeva, A.M.; Shcherbakova, T.M.; Pryanishnikov, V.K.

1984-07-01

79

Effects of ion-exchangeable cations on coal ash mineralogy  

Energy Technology Data Exchange (ETDEWEB)

The purpose of this study was to investigate the effect of ion-exchangeable cations on ash mineralogies of two coals having different sodium contents. In addition, ashes of the same coals from which the exchangeable cations were removed were compared with ashes of the non-exchanged coals to determine the effect of removing alkali cations on ash mineralogies. Two lignites from the Gascoyne Mine, North Dakota, were chosen for this study. Both samples were collected within the same coal seam but from different pits: the Gascoyne Red and Blue Pits. Based on pilot plant combustion experience, the Gascoyne Red Pit coal is characterized as a low-fouling lignite relatively low in sodium, while the Gascoyne Blue Pit coal is a moderate to high-fouling lignite relatively high in sodium. Ion-exchange data for these two coals has been previously reported. Results suggest that systems abundant in calcium and sodium cations form feldspathoids at lower temperatures than systems deficient in these cations by mechanisms previously described. At 1000/sup 0/C, both calcium and sodium were present in the form of gehlenite and nepheline, respectively. In no case did mutual substitution of calcium and sodium occur within the same aluminosilicate structure. Perhaps this behavior reflects a preference for specific cations to substitute within aluminosilicate structures having different coordination configurations. 6 references, 2 tables.

Falcone, S.K.; Hurley, J.P.; Schobert, H.H.

1984-11-01

80

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

 
 
 
 
81

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

International Nuclear Information System (INIS)

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

1998-04-01

82

Radioactivity of coal ash used in building materials  

International Nuclear Information System (INIS)

In Germany every year about 18 million tonnes of combustion by-products are produced in coal-fired power stations. In 1996 these by-products were boiler slag (about 3 million tonnes), bottom ash (about 3 million tonnes) and above all fly ash (about 12 million tonnes). 7.5 million tonnes result from the burning of bituminous coal and 10.3 million tonnes from lignite. About 98 % of the bituminous coal ash is used in construction and mining industry. The majority of lignite ash is used for the filling and re cultivation of open pit mines, it is utilized either unmixed or mixed with FGD ( flue-gas desulfurization) gypsum and FGD water. The natural radioactivity of coal and also of the ash mainly results from many natural radionuclides in the decay series of uranium-radium, thorium and to an insignificant extent of uranium-actinium, as well as from potassium-40. Because of the age of coal, the activity concentrations of the different radionuclides are in a radioactive equilibrium. 'Therefore it is sufficient to consider the significant radionuclides for the radiation doses in each natural decay series, namely radium-226 and thorium-232 with their daughters radon-222 and radon-220 and also potassium-40. lie contribution of the radionuclides of the uranium-actinium series to the radiation dose can be neglected. (authors)

1997-11-16

83

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

84

Prediction of ash deposition in pulverized coal combustion systems  

Energy Technology Data Exchange (ETDEWEB)

A predictive scheme based on CCSEM flyash data and Computational Fluid Dynamics (CFD) has been developed to study the slagging propensity of coals. The model has been applied to predict the deposition potential of three UK coals; Bentinck, Daw Mill and Silverdale, in a pilot scale single burner ash deposition test facility and an utility size multi-burner front wall-fired furnace. The project is part of a collaborative research program sponsored by the UK Department of Trade and Industry and involved various industrial organizations and universities. The objective of the project is to understand the fundamental aspects of slagging in pulverized coal-fired combustion systems. This paper is a sequel to the poster paper entitled: The Prediction of Ash Deposition in a Coal Fired Axi-symmetric Furnace, presented in the last Engineering Foundation Conference. The present model predicts the relative slagging propensity of the three coals correctly. The predicted deposition patterns are also consistent with the observations. The results from the model indicate a preferential deposition of iron during the initial stage of ash deposition. The average compositions of the deposits become closer to that of the bulk ash when the accumulation of ash deposits is taken into account.

Lee, F.C.C.; Riley, G.S. [National Power PLC, Swindon (United Kingdom); Lockwood, F.C. [Imperial Coll. of Science, Technology and Medicine, London (United Kingdom). Dept. of Mechanical Engineering

1996-12-31

85

Fluidized bed combustion of high ash coals  

Energy Technology Data Exchange (ETDEWEB)

The behavior of the fluidized bed combustion of high ash chars is analyzed by applying the two-phase theory, the gas flowing in plug flow both in the emulsion and bubble phases. The ash is assumed to remain attached to the char particle and therefore the shrinking core model is considered.

Lemcoff, N.O. (PINMATE - Dpto. de Industrias, Univ. of Buenos Aires (AR))

1988-01-01

86

Chemical changes in different types of coal ash during prolonged, large scale, contact with seawater.  

Science.gov (United States)

In this study, we followed the chemical changes occurring in coal ash exposed to prolonged (300 days), large scale, contact with running seawater. Four major components (Al, Ca, Mg, Fe) and seven minor and trace elements (Cd, Cr, Cu, Mn, Zn, Pb, Hg) were measured in four coal ash types: fly and bottom ash freshly obtained from coal-fired power plant, and old ash (crushed and blocks) recovered from the sea after 3-5 years contact with seawater. Changes occurred in the chemical composition of the coal ash along the experiment: Fe increased in fresh ash, Al increased in old ash and Ca increased in all ash types except old ash blocks. Cu and Hg decreased in fresh fly ash while Cr increased, Cd decreased in all ash types except bottom ash, and Mn decreased in bottom ash. Most of the changes occurred in the fresh fly ash, and not in the old ash, indicating equilibrium after prior exposure to seawater. In addition, more changes occurred in fresh fly ash than in bottom ash, emphasizing the differences between the two ash types. While the changes in the concentrations of the major elements may be an indication of the integrity of the ash matrix, the only elements of environmental significance released to the environment were Hg and Cd. However, calculated seawater concentrations were much lower than seawater quality criteria and therefore the coal ash was considered suitable for marine applications concerning seawater quality. PMID:12623087

Shoham-Frider, Efrat; Shelef, Gedaliah; Kress, Nurit

2003-01-01

87

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

88

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

1997-10-01

89

Toxicity of and metals in coal combustion ash leachate  

International Nuclear Information System (INIS)

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

1997-01-01

90

SIROASH gauges for on-line determination of ash in coal  

International Nuclear Information System (INIS)

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

1982-01-01

91

Fly ash and coal conversion by-products  

Energy Technology Data Exchange (ETDEWEB)

This book includes in papers concerned with the by-products of SO{sub 2} control technologies - for example, wet scrubbing, sorbent injection, FBC, LIM, coal beneficiation, etc. With world-wide efforts to control acid precipitation, the amounts of these materials are steadily increasing. Characterization shows them to be easily as complex as coal ash, with indications of undesirable sulphide reported for the first time. These products do not adapt easily to existing ash utilization schemes, but promising applications of FBC ash to Portland cement-free concrete and other structural products were discussed. In another promising utilization option, it is shown that soon-to-be-commercialized foamed glass can be made from fly ash. Materials design and processing for this large-scale application are reported to be dependent only on ash composition rather than physical properties. The authors present knowledge of the microstructure, mineralogy and properties of fly ashes. In particular, XRD and TEM studies of the NISTs fly ash standard reference materials have led to quantification of the crystalline phases and a nanostructure-level look at phase separation and crystallization in the glass phases.

Hemmings, R.T.; Berry, E.E. (Matex Consultants, Inc., Mississauga, Ontario (CA)); McCarthy, G.J. (North Dakota State Univ., Fargo, ND (USA)); Glasser, F.P. (Aberdeen Univ. (United Kingdom))

1989-01-01

92

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.)

1981-01-01

93

Determination of trace elements in coal and coal ash samples by ICP-MS  

Energy Technology Data Exchange (ETDEWEB)

The determination of several trace elements, including thorium and the lanthanides in coal and coal ashes applying total dissolution and ICP-MS, was studied. The procedures were tested with reference materials (Bituminous Coal NIST 1632a and Fly Ash NIST 1633a). For coal samples, chemical ashing with HNO{sub 3}, HF, and HClO{sub 4} produces reasonable results. For coal ash samples, some difficulties related to the determination of rubidium, cesium, thorium, and the lanthanides were found and a proposed solution is discussed. Finally, coal, bottomash, electrostatic precipitator (ESP), and fly ash samples from a Brazilian coal-fired power plant were analyzed and an enrichment of Mn, Zn, Ge, As, Se, Mo, Cd, Sb, Ag, Pb, Bi, and U in fly ash was observed. The values obtained for refractory elements, such as thorium, cerium, and scandium, in the ESP samples were compared with those obtained by INAA, with good agreement between both results. The use of a large number of elements (57) during the instrument calibration allows the use of the TotalQuant mode as a routine method.

Godoy, M.L.D.P.; Godoy, J.M.; Roldao, L.A. [Instituto de Radioprotecao e Dosimetria (IRD), Rio de Janeiro, RJ (Brazil)

2001-07-01

94

New container system expands coal-ash markets  

Energy Technology Data Exchange (ETDEWEB)

A revolutionary new rail container system may be a boon for electric utilities that consider their coal combustion by-products (CCBs) a revenue source rather than a waste requiring disposition. SEEC Inc., a St. Paul, Minn.-based company, has pioneered an airtight container that is ideally united to carrying CCBs and other difficult-to-handle materials in empty coal trains. Recycling combustion by-products has become an attractive option for coal-fired utilities faced with dwindling landfill space and increased technology expenditures to meet environmental regulations. Since the EPA ruled that coal ash is a non-hazardous substance, a host of expanded applications and markets have evolved for CCBs, giving utilities more opportunity to turn an expense into a profit center. Lower-cost shipping will result in a larger market area within which the ash can be competitive.

Hansen, T.

1995-08-01

95

Mineralogy and chemistry of conventional and fluidised bed coal ashes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Coal combustion residues represent very abundant inorganic waste materials. The change from conventional combustion of powdered North Bohemian brown coal to its combustion in fluidised bed boilers in several Czech power and heating plants calls for detailed mineralogical and geochemical characterisation of the combustion residues. The main differences between fly ashes from both combustion systems result from different burning temperatures and differing systems of desulphurisation (coeval wit...

Sulovský P

2002-01-01

96

Preparation and characterization of carbon-enriched coal fly ash  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Carbon-enriched fractions have been obtained from two coal fly ash (FA) samples. The FA came from two pulverized-coal fired power stations (Lada and Escucha, Spain) and were collected from baghouse filters. Sieving was used to obtain carbon-enriched fractions, which were further subjected to two beneficiation processes: acid demineralization using HCl and HF, and oil agglomeration using soya oil–water. Yield in weight after sieving, unburned carbon content, and several physicochemical chara...

2008-01-01

97

Coal fly ash as an amendment to container substrate for Spathiphyllum production.  

Science.gov (United States)

Coal fly ash, possessing alkalinity and containing some essential mineral elements, could be an alternative to lime amendment and a nutrient source of container substrates for ornamental plant growth. This study examined physiochemical properties of three fly ashes collected from Florida, Michigan, and North Carolina and container substrates formulated by incorporating commercial dolomite and the three fly ashes, respectively into a soilless basal substrate. The basal, dolomite- and fly ash-amended substrates were used to grow peace lily (Spathiphyllum Schott 'Ty's Pride'), a popular ornamental foliage plant, in 15-cm diameter containers in a shaded greenhouse. Electrical conductivities and pH of the substrates were monitored monthly. Plant canopy heights and widths, shoot fresh and dry weights were recorded five months after transplanting, and tissue nutrient contents were measured. Three fly ashes and the commercial dolomite were able to raise pH of the basal substrate from 3.8 to about 6.8. Canopy heights and widths as well as shoot fresh and dry weights of plants produced from fly ash-amended substrates were comparable to those produced from dolomite-amended substrate but significantly different from those produced from the basal substrate. On an average, five necrotic leaves appeared from plants produced in the basal substrate; however, less than one necrotic leaf occurred on plants produced in either dolomite- or fly ash-amended substrates. As a result, the quality grade of plants grown in the basal substrate was low, and plants were not marketable. Additionally, electrical conductivities of fly ash-amended substrates were consistently higher during the course of plant growth, suggesting that, in addition to neutralizing pH, the amended fly ashes provide nutrients for peace lily growth, which was confirmed by high nutrient contents in plant shoots. This study demonstrates that the three fly ashes can be alternatives to commercial dolomites used as amendments to soilless substrates for ornamental plant production. Utilization of fly ashes as container substrate amendments should represent a new market for the beneficial use of coal combustion byproducts. PMID:16214336

Chen, Jianjun; Li, Yuncong

2006-10-01

98

High fire resistance in blocks containing coal combustion fly ashes and bottom ash.  

Science.gov (United States)

Fire resistance recycled blocks, containing fly ash and bottom ash from coal combustion power plants with a high fire resistance, are studied in this paper by testing different compositions using Portland cement type II, sand, coarse aggregate and fly ash (up to 50% of total weight) and bottom ash (up to 30% of total weight). The fire resistance, physical-chemical (density, pH, humidity, and water absorption capacity), mechanical (compressive and flexural strength), and leaching properties are measured on blocks made with different proportions of fly ash and bottom ash. The standard fire resistance test is reproduced on 28cm-high, 18cm-wide and 3cm-thick units, and is measured as the time needed to reach a temperature of 180°C on the non-exposed surface of the blocks for the different compositions. The results show that the replacement of fine aggregate with fly ash and of coarse aggregate with bottom ash have a remarkable influence on fire resistance and cause no detriment to the mechanical properties of the product. Additionally, according to the leaching tests, no environmental problems have been detected in the product. These results lead to an analysis of the recycling possibilities of these by-products in useful construction applications for the passive protection against fire. PMID:21511456

García Arenas, Celia; Marrero, Madelyn; Leiva, Carlos; Solís-Guzmán, Jaime; Vilches Arenas, Luis F

2011-08-01

99

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 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

1999-08-13

100

The potential of biological sludge amended combustion coal ash residues as artificial plant growth media : a laboratory column study to assess the influence of weathering on elemental release  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Sasol biological sludge, coal fine and gasification ash were the three waste streams involved in this study. The main concern is that on their own they are not suitable as growth mediums, the ash is alkaline (pH>12) with high salinity (total dissolved solids of 8000 mg ?-1). Fine ash is microporous (particle size diameter <250 ?m) and forms cemented layers that can restrict root growth while, gasification ash in macroporous (most particle size diameter ranged between 1 and 75 mm) and has a...

2012-01-01

 
 
 
 
101

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

102

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 "2"3"8Pu-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)

1975-01-01

103

Phase-mineral and chemical composition of coal fly ashes as a basis for their multicomponent utilization. 1. Characterization of feed coals and fly ashes  

Energy Technology Data Exchange (ETDEWEB)

The phase-mineral and chemical composition of feed coals and their fly ashes (FAs) produced in four large Spanish thermo-electric power stations was characterized as a basis for multicomponent FA utilization. The feed fuels used are bituminous coals, semi-anthracites and anthracites with high detrital mineral abundance and mixed carbonate and sulphide sulphate authigenic mineral tendency. Their mineral composition includes quartz, kaolinite, illite muscovite, pyrite, chlorite, plagioclase, K-feldspar, gypsum, siderite, calcite, dolomite, marcasite, montmorillonite, jarosite, and ankerite. The FAs studied have aluminosilicate composition with higher concentrations of alkaline and alkaline-earth oxides than Fe oxide. Elements such as Ag, As, Ba, Cr, Cs, Li, P, Sb, Sc, Sn, Sr, Ti, V, Zn, and Zr are relatively enriched in these FAs in comparison with the respective mean values for bituminous coal ashes worldwide. The FAs consist basically of aluminosilicate glass, to a lesser extent of mineral matter (with high silicate abundance and dominant oxide tendency) and moderate char occurrence. The phase-mineral composition (in decreasing order of significance) of these FAs is normally glass, mullite, quartz, char, kaolinite metakaolinite, hematite, cristobalite, plagioclase, K-feldspar, melilite, anhydrite, wollastonite, magnetite and corundum plus 42 important accessory minerals or phases. A scheme of conventional separation procedures was applied to recover sequentially six initial and potentially useful and/or hazardous products from FAs, namely: (1) a ceramic cenosphere concentrate; (2) a water-soluble salt concentrate; (3) a magnetic concentrate; (4) a char concentrate; (5) a heavy concentrate; and finally (6) an improved FA residue. 29 refs., 6 figs., 10 tabs.

Stanislav V. Vassilev; Rosa Menendez; Diego Alvarez; Mercedes Diaz-Somoano; M. Rosa Martinez-Tarazona [Bulgarian Academy of Sciences, Sofia (Bulgaria). Central Laboratory of Mineralogy and Crystallography

2003-10-01

104

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

Energy Technology Data Exchange (ETDEWEB)

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

Kruse, C.W.

1991-01-01

105

Research on weeds prevention using coal ash during the period of Zoysia Japonica planting  

Energy Technology Data Exchange (ETDEWEB)

Based on the pot experiments, the germination rates of Zoysia Japonica planted in coal ashes and in soils were examined, and then the weed protection by coal-ashes in the field planted with Zoysia Japonica was investigated in the period of lawn construction. The results indicate that the germination rate of Zoysia Japonica planted in coal-ashes with pot experiments is 83%, while that of CK is 84.33%. In field experiments, the rate of weed control by coal-ashes exceeds 96% and the favorite thickness of coal-ashes was about 2 cm. 9 refs., 1 fig., 4 tabs.

Fang, Y.; Feng, Z.; Hu, Y. [Chinese Academy of Sciences, Beijing (China). Inst. of Geographical Sciences and Natural Resources

2005-03-01

106

Revegetation of a coal fly ash - reject landfill  

Energy Technology Data Exchange (ETDEWEB)

Coal-fired power plants dispose of coal fly ash in landfills worldwide. More than 100 million metric tons of fly ash are produced annually in the United States alone and continued worldwide reliance on coal may pose a significant environmental risk. Ecologists at the Savannah River Site (SRS) near Aiken, South Caroline have found high levels of metals in animals exposed to coal fly ash and coal reject from coal burning at their own facility and suspect the problem is widespread. Recent studies have shown that selenium may cause morphological deformities in bullfrog tadpoles and further research into this problem is required. This study began in June 2000 and involved an outdoor tank mesocosm that replicated a coal fly ash basin field study at SRS to find ways to minimize the infiltration rate of water into the substrate. With time, the water becomes acidic leachate from the oxidation of pyrite and significantly damages adjacent ecosystems. Leachate samples were measured for pH and electroconductivity. The levels of various trace elements in the leachate were also discussed. One way to minimize the volume of leachate is to revegetate the area in order to optimize evapotranspiration. The vegetation also acts as a buffer to organic metabolites from root activities and plant decay. Many improvement materials were added in the field to promote the buffering capacity and to improve the physical properties of the substrate. Results indicated that pH has increased since the inception of the study. The biosolid plus topsoil plus surfactant treatment seems to be an effective method for increasing the buffering capacity. The most effective treatment for inducing the lowest electroconductivity values is the addition of topsoil plus surfactant. 1 ref., 2 figs.

Danker, R.; Adriano, D.C.; Barton, C.; Punshon, T.

2001-07-01

107

Assessing the catalytic effect of coal ash constituents on the CO2 gasification rate of high ash, South African coal  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The catalytic effect of inorganic species, within the ash, on the CO2 gasification of three South African coals containing similar carbon-structural properties (elemental, structural and petrographical properties) was assessed. The reactivity of the coals with a particle size between 150 and 250 ?m was determined in a thermo gravimetric analyser. The reactivity was measured at temperatures between 900 and 1000 °C, pressures between 1 and 10 bar, and fractions of CO2 between 10 and 30%. For ...

2011-01-01

108

Cast-concrete products made with FBC ash and wet-collected coal-ash  

Energy Technology Data Exchange (ETDEWEB)

Cast-concrete hollow blocks, solid blocks, and paving stones were produced at a manufacturing plant by replacing up to 45% (by mass) of portland cement with fluidized bed combustion (FBC) coal ash and up to 9% of natural aggregates with wet-collected, low-lime, coarse coal-ash (WA). Cast-concrete product specimens of all three types exceeded the compressive strength requirements of ASTM from early ages, with the exception of one paving-stone mixture, which fell short of the requirement by less than 10%. The cast-concrete products made by replacing up to 40% of cement with FBC ash were equivalent in strength (89-113% of control) to the products without ash. The abrasion resistance of paving stones was equivalent for up to 34% FBC ash content. Partial replacement of aggregates with WA decreased strength of the products. The resistance of hollow blocks and paving stones to freezing and thawing decreased appreciably with increasing ash contents. The cast-concrete products could be used indoors in regions where freezing and thawing is a concern, and outdoors in a moderate climate.

Naik, T.R.; Kraus, R.N.; Chun, Y.M.; Botha, F.D. [University of Wisconsin, Milwaukee, WI (United States)

2005-12-01

109

Coal ash leachability: detailed field studies  

Energy Technology Data Exchange (ETDEWEB)

At the Latrobe Valley power station complexes ash from the power station is disposed of by mixing with water and pumping the resultant slurry into a disposal pond. After 6-12 months it is considered as leached ash and transferred to the overburden dump. Leachability under field conditions is a key challenge for the environmental management of the disposal site in the overburden dump. To assess the overall processes of field leachability, trial leaching cells were established at the Loy Yang Ash Pond in mid 1997 and monitored to enable the determination of a water and solute balance. A review of the performance of these cells is given up to the end of May 1998. 7 refs., 4 figs., 3 tabs.

Mudd, G.M.; Kodikara, J.; McKinley, T. [Victoria University of Technology, Footscray, Vic. (Australia). School of the Built Environment

1998-12-31

110

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

111

Growth of crops in soil with coal ash additions (V): the effect of coal ash addition on various types of soil  

Energy Technology Data Exchange (ETDEWEB)

A study has been made of the suitability of coal ash as a soil conditioner, the aim being its agricultural utilization. The main constituents of the coal ash under test were Si and Al. When mixed with sulfate acidic Kuroboku soils, coal ash was less effective than calcium carbonate in correcting acidity, and large additions were required to obtain satisfactory pH values. Coal ash/soil mixtures were packed in columns and after addition of salt water, the electric conductivity and Ca of the eluate were analyzed. It was discovered that the Ca content is readily leached by salt water. 9 references.

Aoki, M.; Okabe, K.; Ogawa, T.; Misonoh, J.; Nakaoka, A.; Fukushima, M.

1984-01-01

112

The occurrence of quartz in coal fly ash particles  

Energy Technology Data Exchange (ETDEWEB)

Quartz is present in both coal and residual ash. Ash originates from combustion of pulverised coal and, once removed from the flue gases by electrostatic precipitators (ESPs), it is called pulverized fuel ash (PFA). Thus, occupational exposure to PFA could also include exposure to silica. However, epidemiological studies did not show evidence of progressive massive fibrosis (PMF). In vitro tests demonstrated that PFA is less toxic than silica, and in vivo data of PFA did not support the importance of silica content for toxicity. Commissioned by the Dutch coal-fired power plants, KEMA has started a research project to determine the quartz content in coal and the corresponding PFA. It appears that on average 50% of the alpha-quartz in coal is found again in the total fraction of PFA (D50(ae) 31 {mu}m, where D50(ae) is the aerodynamically mass median diameter), whereas 16% is found in an even finer fraction (D50(ae) 10 {mu}m). The remaining part of the quartz is embedded in a glass phase. Scanning electron microscopy (SEM) with x-ray microanalyses (XMA) of cross-sections of 11,130 ash particles showed that quartz in PFAis present as unmelted sand particles. These quartz particles are angularly shaped. However, two types are to be distinguished: free coarse angular quartz particles (not respirable) and small angular quartz particles within the PFA particles. From the SEM/XMA results, it has to be concluded that the quartz in the respirable fraction is predominantly present within the original molten PFA particle. Since the effects of quartz are surface related, this elucidates the negative results of quartz-related effects of PFA in epidemiological, in vitro and in vivo studies. Besides, the amount of the total alpha-quartz in the respirable fraction of the ashes studied is less than 0.2%, so probably the Dutch occupational quartz standard of 0.075 mg m{sup 3} will not be exceeded.

Meij R.; Nagengast S.; Winkel H.T.

2000-10-15

113

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

114

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

Directory of Open Access Journals (Sweden)

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

Budi Sulistianto

2012-07-01

115

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

2013-01-01

116

Sulfur removal from lignite using alkaline solution from tea waste ash by water extraction  

Energy Technology Data Exchange (ETDEWEB)

Some high-sulfur lignites were extracted with aqueous alkaline solution obtained from the water-soluble fraction of tea waste ash. High-sulfur removal from lignites was possible by this method. The effects of temperature, the amount of tea waste ash used, extraction time, and stirring speed were studied in the ranges 5-35 g, 350-550 K, 0.042-1.7 MPa, 15-60 min, and 300-600 rev/min, respectively. The extents of pyritic and organic sulfur removal were investigated. (Author)

Demirbas, A.

2000-10-01

117

Application of coal ash to environmental improvement Transformation into zeolite, potassium fertilizer, and FGD absorbent  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The rapid increase in population and economic growth have led to an increase in energy demand. Coal reserves are distributed worldwide, and coal is now known to be the most stable and available energy source. However, utilization of coal as an energy source involves the generation of a great amount of coal ash, and the recycling rate of the ash is rather low. Coal ash is mainly used in civil construction materials, and there is a limit to the demand for coal ash by construction...

Kikuchi, R.

1999-01-01

118

Clay formation and metal fixation during weathering of coal fly ash  

International Nuclear Information System (INIS)

The enormous and worldwide production of coal fly ash cannot be durably isolated from the weathering cycle, and the weathering characteristics of fly ash must be known to understand the long-term environmental impact. The authors studied the weathering of two coal fly ashes and compared them with published data from weathered volcanic ash, it's closest natural analogue. Both types of ash contain abundant aluminosilicate glass, which alters to noncrystalline clay. However, this study reveals that the kinetics of coal fly ash weathering are more rapid than those of volcanic ash because the higher pH of fresh coal fly ash promotes rapid dissolution of the glass. After about 10 years of weathering, the noncrystalline clay content of coal fly ash is higher than that of 250-year-old volcanic ash. The observed rapid clay formation together with heavy metal fixation imply that the long-term environmental impact of coal fly ash disposal may be less severe and the benefits more pronounced than predicted from previous studies on unweathered ash. Their findings suggest that isolating coal fly ash from the weathering cycle may be counterproductive because, in the long-term under conditions of free drainage, fly ash is converted into fertile soil capable of supporting agriculture

1999-10-01

119

Clay formation and metal fixation during weathering of coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

The enormous and worldwide production of coal fly ash cannot be durably isolated from the weathering cycle, and the weathering characteristics of fly ash must be known to understand the long-term environmental impact. The authors studied the weathering of two coal fly ashes and compared them with published data from weathered volcanic ash, it's closest natural analogue. Both types of ash contain abundant aluminosilicate glass, which alters to noncrystalline clay. However, this study reveals that the kinetics of coal fly ash weathering are more rapid than those of volcanic ash because the higher pH of fresh coal fly ash promotes rapid dissolution of the glass. After about 10 years of weathering, the noncrystalline clay content of coal fly ash is higher than that of 250-year-old volcanic ash. The observed rapid clay formation together with heavy metal fixation imply that the long-term environmental impact of coal fly ash disposal may be less severe and the benefits more pronounced than predicted from previous studies on unweathered ash. Their findings suggest that isolating coal fly ash from the weathering cycle may be counterproductive because, in the long-term under conditions of free drainage, fly ash is converted into fertile soil capable of supporting agriculture.

Zevenbergen, C.; Bradley, J.P.; Reeuwijk, L.P. Van; Shyam, A.K.; Hjelmar, O.; Comans, R.N.J.

1999-10-01

120

Microwave-assisted sample preparation of coal and coal fly ash for subsequent metal determination  

Energy Technology Data Exchange (ETDEWEB)

The aim of this paper is to review microwave-assisted digestion of coal and coal fly ash. A brief description of microwave heating principles is presented. Microwave-assisted digestion appears currently to be the most popular preparation technique, possibly due to the comparatively rapid sample preparation and the reduction of contamination, compared to the conventional hot-plate digestion methods.

Srogi, K. [Inst. of Chemical Processing of Coal, Zabrze (Poland)

2007-01-15

 
 
 
 
121

Natural radioactivity of coals from Upper Silesian Coal Basin and their ash content  

International Nuclear Information System (INIS)

The results of the study of natural radioactivity of Upper Silesian's coal are presented. The histograms of contents of 226Ra, 228Ra and 40K in the main groups of carbon layers are given. Analysis of correlations between contents of natural radionuclides and ash content in different coal layers was made. The correlations were stated. 12 refs., 7 figs., 4 tabs. (author)

1988-01-01

122

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

International Nuclear Information System (INIS)

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

1982-01-01

123

Experimental determination of the equivalent thermal diffusivity for porous coal-ash particles  

Energy Technology Data Exchange (ETDEWEB)

The equivalent thermal diffusivity of spherical porous coal-ash particles has been determined by measuring the temperature response curve both in the center and on the surface. In this paper a general relationship between the equivalent thermal diffusivity of the porous coal-ash particles and the ash content within the coal is obtained. Based on this relationship, prediction of the burning rate of a large coal char particle becomes possible.

Fu, W.B.; Zhang, B.L.; Zheng, S.M. (Tsinghua Univ., Beijing, BJ (China))

1992-12-01

124

Coal ash and calcium carbonate on acid drainage mitigation in coal mining overburden  

Energy Technology Data Exchange (ETDEWEB)

Acid drainage is an environmental problem, not exclusive, but commonly associated to coal mines. It arises from the oxidation of sulfides, like pyrite, in overburden and mining tailings. The use of ashes from coal combustion is still limited in Brazil, but such residues have a potential use as neutralizing agent for acid mine drainage. This study intended to evaluate the interaction between the use of coal ash and CaCO3 to neutralize acid drainage from pyrite oxidation in coal mining overburden from Candiota (RS) - Brazil. Samples of overburden material containing pyrite were treated with increasing CaCO3 doses and coal ash in leaching flasks. The treatments were disposed in a completely randomized design in 4 x 4 factorial scheme (4 doses of CaCO3 and 4 doses of coal ash) with three replications. The flasks were submitted every two weeks to leaching with distilled water during eight months. The leached solutions were analyzed for pH, free acidity and S, Si and Fe contents. Results showed that the use of ash was impractical not only due to its low neutralizing capacity, but also because it reduced the CaCO3 efficiency. After eight months of simulated weathering only 11% of the sulfides were oxidized in the absence of ash or carbonate. The use of CaCO3 and, to a lesser extent of ash, increased the pyrite oxidation rate. Pyrite in coal overburden oxidized faster in the first two months of simulated weathering, thus it is recommended that lime be applied just after overburden exposition in order to minimize acid drainage. Further investigation aiming to optimize the CaCO3 doses and test alternative neutralizing materials in long term experiments should be encouraged.

Soares, E.R.; de Mello, J.W.V.; Schaefer, C.E.G.R.; da Costa, L.M. [URCAMP, Bage (Brazil)

2006-01-15

125

Ash removal from coal extracts in a lamellar sedimentation tank  

Energy Technology Data Exchange (ETDEWEB)

Problems are discussed associated with removal of mineral matter and residues from raw coal extracts during coal liquefaction. Efficiency of ash removal from a raw coal extract (produced from black coal) by means of a lamellar thickener was analyzed under laboratory conditions. Coal extract with 7.7% solid content (cresol-insoluble particles), 18% coal extract and 74.3% solvent oil was used. The thickener was 1.2 m long and 0.75 m high. The lamellae (each 2.05 m/sup 2/ large) were installed at an interval of 0.05 m and were inclined at an angle of 55 degrees. Cross-flow scheme was used. Temperature ranged from 175 to 190 C. Three flow rates were used: 55.0 kg/h, 22.3 kg/h and 16.0 kg/h. Test results are given in 3 tables. When optimum temperature and flow rates were used degree of ash removal after 4 hours increased to 100%. The lamellar thickener tested under laboratory conditions is characterized by uncomplicated design, low investment and high efficiency. 13 references.

Rusin, E.; Pietrzok, B.; Pasinski, A.; Broz, A.

1985-11-01

126

An investigation on radon exhalation from fly ash produced in the combustion of coal  

International Nuclear Information System (INIS)

Fly ash is the end product of coal combustion and coal. Like most earthen materials it contains 238U the parent element of the uranium decay series which support several radioactive decay products including radon. Radon exhalation rate from fly ash produced by thermal power station has been measured and compared with that from different kinds of soil and from coal itself. It is observed that the radon exhalation rate from fly ash is less than that from soil and coal, although fly ash contains a higher concentration of uranium than typical soil. The addition of fly ash as an additive to soil does not significantly suppress radon exhalation from soil. (author)

2003-10-16

127

Synthesis of granular zeolitic materials with high cation exchange capacity from agglomerated coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

Fly ash from coal combustion is a potential source of pollution and there is continuous interest in its recycling by converting it into products such as zeolitic materials for use in retaining pollutants. In this paper, production of granular zeolitic material from a commercially-unusable fine-fraction of a lightweight aggregate (LA) building material made from coal fly ash agglomerated with lime, by conventional alkaline activation is described. NaP1 zeolite, K-F zeolite, K-Phillipsite and K-Chabazite were synthesised. The process was optimised by combining four reaction parameters (temperature, alkali concentration, solution/fly ash ratio and reaction time). Zeolitic materials with the highest zeolite yields and cation exchange capacities were selected for future application in environmental processes. End-product zeolitic materials maintain its granular form and this could favour their use in some particular applications for environmental waste treatment (e.g. ionic exchange in column) without any further transformation stages. 21 refs., 6 figs., 6 tabs.

Roberto Juan; Susana Hernandez; Jose Manuel Andres; Carmen Ruiz [Instituto de Carboquimica (CSIC), Zaragoza (Spain)

2007-08-15

128

Ash level meter for a fixed-bed coal gasifier  

Energy Technology Data Exchange (ETDEWEB)

An ash level meter for a fixed-bed coal gasifier is provided which utilizes the known ash level temperature profile to monitor the ash bed level. A bed stirrer which travels up and down through the extent of the bed ash level is modified by installing thermocouples to measure the bed temperature as the stirrer travels through the stirring cycle. The temperature measurement signals are transmitted to an electronic signal process system by an FM/FM telemetry system. The processing system uses the temperature signals together with an analog stirrer position signal, taken from a position transducer disposed to measure the stirrer position to compute the vertical location of the ash zone upper boundary. The circuit determines the fraction of each total stirrer cycle time the stirrer-derived bed temperature is below a selected set point, multiplies this fraction by the average stirrer signal level, multiplies this result by a appropriate constant and adds another constant such that a 1 to 5 volt signal from the processor corresponds to a 0 to 30 inch span of the ash upper boundary level. Three individual counters in the processor store clock counts that are representative of: (1) the time the stirrer temperature is below the set point (500/sup 0/F), (2) the time duration of the corresponding stirrer travel cycle, and (3) the corresponding average stirrer vertical position. The inputs to all three counters are disconnected during any period that the stirrer is stopped, eliminating corruption of the measurement by stirrer stoppage. 7 figures.

Fasching, G.E.

1982-10-12

129

Ash level meter for a fixed-bed coal gasifier  

Energy Technology Data Exchange (ETDEWEB)

An ash level meter for a fixed-bed coal gasifier is provided which utilizes the known ash level temperature profile to monitor the ash bed level. A bed stirrer which travels up and down through the extent of the bed ash level is modified by installing thermocouples to measure the bed temperature as the stirrer travels through the stirring cycle. The temperature measurement signals are transmitted to an electronic signal process system by an FM/AM telemetry system. The processing system uses the temperature signals togerther with an analog stirrer position signal, taken from a position transducer disposed to measure the stirrer position to compute the vertical location of the ash zone upper boundary. The circuit determines the fraction of each total stirrer cycle time the stirrer-derived bed temperature is below a selected set point, multiplies this result by an appropriate constant and adds another constant such that a 1 to 5 volt signal from the processor corresponds to a 0 to 30 inch span of the ash upper boundary level. Three individual counters in the processor store clock counts that are representative of: the time the stirrer temperature is below the set point (500/sup 0/ F.), the time duration is below of the corresponding stirrer travel cycle, and the corresponding average stirrer vertical position. The inputs to all three counters are disconnected during any period that the stirrer is stopped, eliminating corruption of the measurement by stirrer stoppage.

Fasching, G.E.

1984-08-21

130

Respiratory and reproductive characteristics of eastern mosquitofish (Gambusia holbrooki) inhabiting a coal ash settling basin  

Energy Technology Data Exchange (ETDEWEB)

Coal fly ash and effluent from coal ash settling basins negatively affects metabolism and reproduction in a variety of organisms, including a number of fish species. Some species, most notably the eastern mosquitofish (Gambusia holbrooki), are known to maintain viable populations in areas contaminated by coal ash. While eastern mosquitofish are present in these systems, their degree of tolerance to coal ash has not been investigated using sublethal metrics of exposure. It is possible that eastern mosquitofish persist in habitats affected by coal ash, but experience significant costs such as changes in metabolism and fecundity. Thus, we investigated the effects of coal ash on standard metabolic rate and reproduction of eastern mosquitofish inhabiting a coal-ash contaminated settling basin. Standard metabolic rates of mosquitofish from the ash contaminated site and a reference site were not significantly different. Despite elevated contaminant concentrations in ash basin females (selenium, arsenic, copper, and cadmium) and their offspring (selenium), brood sizes and offspring viability did not differ between clutches collected from ash basin and reference site females. Our data provide further evidence of the high degree of tolerance of eastern mosquitofish to exposure to aquatic coal ash disposal generated by power plants. However, the basis for such tolerance to ash remains unclear. Further investigations are required to determine whether such tolerance is a result of species-specific characteristics or population characteristics due to local adaptation.

Staub, B.P.; Hopkins, W.A.; Novak, J.; Congdon, J.D. [University of Georgia, Aiken, SC (United States). Savannah River Ecology Lab.

2004-01-01

131

Rainfall erosion characteristics of soil stabilized with coal ash  

Energy Technology Data Exchange (ETDEWEB)

The authors report a series of experiments in which artifical rainfall was used to ascertain the erosion which might occur due to the effect of rain on slopes of coarse ash. Sandy and cohesive soils were subjected to rainfalls of 100 mm/hour intensity and their resistance to rainfall erosion assessed in terms of the dry weight (per unit area of specimen surface) of the particle separated from the specimen. The experiments have revealed that, in sandy soils treated with slaked lime and coarse coal ash, a continuous structure forms between the particles of soil, and that this structure is highly resistant to the impact of rain drops. The formation of this structure is due to a C-S-H gel forms on the surface of the coarse ash particles. 3 references.

Torii, K.; Kasaba, S.; Kawamura, M.; Taniguchi, K.

1984-01-01

132

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

133

Dry bottom ash technology improves coal fired boiler operations  

Energy Technology Data Exchange (ETDEWEB)

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

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

2004-07-01

134

Thermal expansion of slag and fly ash from coal gasification  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2006-01-01

135

Kinetics of Alkaline Activation of Slag and Fly ash-Slag Systems  

Science.gov (United States)

Alkali-activated aluminosilicates, commonly known as "geopolymers", are being increasingly studied as a potential replacement for Portland cement. These binders use an alkaline activator, typically alkali silicates, alkali hydroxides or a combination of both along with a silica-and-alumina rich material, such as fly ash or slag, to form a final product with properties comparable to or better than those of ordinary Portland cement. The kinetics of alkali activation is highly dependent on the chemical composition of the binder material and the activator concentration. The influence of binder composition (slag, fly ash or both), different levels of alkalinity, expressed using the ratios of Na2O-to-binders (n) and activator SiO2-to-Na2O ratios (Ms), on the early age behavior in sodium silicate solution (waterglass) activated fly ash-slag blended systems is discussed in this thesis. Optimal binder composition and the n values are selected based on the setting times. Higher activator alkalinity (n value) is required when the amount of slag in the fly ash-slag blended mixtures is reduced. Isothermal calorimetry is performed to evaluate the early age hydration process and to understand the reaction kinetics of the alkali activated systems. The differences in the calorimetric signatures between waterglass activated slag and fly ash-slag blends facilitate an understanding of the impact of the binder composition on the reaction rates. Kinetic modeling is used to quantify the differences in reaction kinetics using the Exponential as well as the Knudsen method. The influence of temperature on the reaction kinetics of activated slag and fly ash-slag blends based on the hydration parameters are discussed. Very high compressive strengths can be obtained both at early ages as well as later ages (more than 70 MPa) with waterglass activated slag mortars. Compressive strength decreases with the increase in the fly ash content. A qualitative evidence of leaching is presented through the electrical conductivity changes in the saturating solution. The impact of leaching and the strength loss is found to be generally higher for the mixtures made using a higher activator Ms and a higher n value. Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) is used to obtain information about the reaction products.

Chithiraputhiran, Sundara Raman

136

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

137

Ash chemistry and mineralogy of an Indonesian coal during combustion. Part 1 Drop-tube observations  

Energy Technology Data Exchange (ETDEWEB)

The paper reports a systematic and comprehensive laboratory investigation into the ash chemistry and mineralogical changes undergone by a low-rank Indonesian coal during combustion. Combustion experiments conducted in a drop-tube furnace included ash formation experiments (using cyclone and filter arrangement) under closely controlled conditions in the range of 1200-1400 C and deposition experiments at a probe temperature of 750 C. Tests conducted with raw coal, coal/additive mixtures and washed coal indicated significant changes in ash characteristics. Of the ash formation and deposit samples examined, the raw coal + bauxite showed the lowest glass content and high contents of corundum indicating low ash deposition propensities. When compared to the ash formation samples, the deposit samples showed even significantly lower glass contents and were enriched in quartz. With the exception of the raw coal + bauxite sample, all are characterized by high silica and iron and moderate aluminium contents. In contrast, the raw coal + bauxite sample have low silica and much higher alumina contents which is in agreement with XRD observations. QEMSCAN trademark results showed that the ash particles are sparsely distributed suggesting lack of a deposit initiation layer. Experimental observations suggest that the use of raw coal with bauxite would appear to offer the best performance with respect to handling ash-related issues. Present findings are of practical significance to power utilities employing Indonesian coal as there is no comprehensive work reported in the literature on ash chemistry and mineralogy of such coals. (author)

Vuthaluru, H.B. [Department of Chemical Engineering, Curtin University of Technology, Bentley, Perth Western 6102 (Australia); French, D. [CSIRO Energy Technology, Lucas Heights Science and Technology Centre, Private Mail Bag 7, Bangor New South Wales 2234 (Australia)

2008-06-15

138

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

1981-12-01

139

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

International Nuclear Information System (INIS)

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

1981-01-01

140

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

 
 
 
 
141

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

Directory of Open Access Journals (Sweden)

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

Denise Alves Fungaro

2006-07-01

142

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

International Nuclear Information System (INIS)

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

1980-01-01

143

Uses of radiometric ash concentration measurements in raw brown coal. Nutzeffekt der radiometrischen Aschegehaltsmessung von Rohbraunkohle  

Energy Technology Data Exchange (ETDEWEB)

Considering the necessity of measuring contents of ashes of brown coal promptly, in order to direct the distribution of coal of adequate quality, the possibilities of using radioactive methods of measuring contents of ashes and their advantages are discussed. Thereafter problems of effects of scientific-technical measures are written down and it is carried out how effects of measuring contents of ashes of brown coal by using radiometric methods can be ascertained. With 6 figs., 4 tabs., 59 refs.

Eichfeld, E.; Neubert, J.; Seidel, G.

1986-01-01

144

Refractories for dry ash coal gasifiers  

Energy Technology Data Exchange (ETDEWEB)

This report summarizes the findings of a 9-yr research program, sponsored by the US Department of Energy and conducted by the Bureau of Mines, to evaluate refractory liner materials for coal gasifier reactors. Commercially available refractories were exposed to coal gasifier reactor environments, reproduced in the laboratory with a high-temperature, high-pressure test facility, followed by extensive postexposure evaluation. Thirty-six castable or gunnable refractories and cements and 24 refractory brick were evaluated. The behavior of castable refractories reinforced with stainless steel fibers was also examined. Gas environments that were evaluated included steam, H/sub 2/, CO/sub 2/, CO, and typical high- and low-Btu gas mixtures. Exposure pressures ranged from 100 to 1,000 psig, temperatures from 500/sup 0/ to 1100/sup 0/C, for periods from 50 h to 2000 h. In some exposures, sodium and/or potassium hydroxide were introduced in order to simulate a high-alkali environment. It was found that intermediate- and low-alumina refractories produced from domestically available raw materials, rather than high-alumina refractories produced from imported raw materials, gave the best service as liner materials and that alkali attack was probably not a serious problem with most refractories. Based on the results of this program, good choices of refractory liner materials for gasifier reactors can be made. 7 references, 25 figures, 30 tables.

Sadler, L.Y. III; Heystek, H.; Raymon, N.S.; Clancy, T.A.

1984-01-01

145

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

146

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

147

Investigation of the use of coal refuse-fly ash compositions as highway base course material  

Science.gov (United States)

The utilization of coal refuse-fly ash compositions as highway base course material is surveyed. The results of a laboratory testing program into the physical and engineering properties of mixtures of these waste products are presented. A comparison of serviceability index and physical damage parameters based on the VESYS Predictive Design Procedure between crushed stone and coal refuse-fly ash compositions are presented. These findings indicate that substituting stabilized coal refuse-fly ash blends in place of conventional base course material is technically and economically feasible. Procedures for developing design mixes and conducting field tests of coal refuse-fly ash base course material are described.

McQuade, P. V.; Head, W. J.; Anderson, R. B.

1981-06-01

148

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 geopolymer matrix, while excellent immobilization of Zn2+, Cu2+, Cd2+, and Cr3+ are reported.

2009-09-15

149

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

150

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

151

Co-composting of sewage sludge and coal fly ash: nutrient transformations  

Energy Technology Data Exchange (ETDEWEB)

The effect of coal fly ash on nutrient transformations during sludge composting co-composting sewage sludge with coal fly ash was evaluated by co-composting sewage sludge with coal fly ash. Dewatered anaerobically-digested sewage sludge was mixed with sawdust used as a bulking agent at 2:1 (w/w), and the mixtures were amended with coal fly ash at 0, 10, 25 and 35% and composted for 100 days. Addition of coal fly ash raised the pH of the sludge compost throughout the composting period; but significant inhibition of decomposition activity occurred only at 35% ash amendment level. Soluble organic carbon and total C decreased according to composting time, whereas total N showed an opposite trend for all treatments.

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

1999-01-01

152

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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.

2011-01-01

153

Ash deposition in the Coal Fired Flow Facility while burning Illinois {number_sign}6 coal  

Energy Technology Data Exchange (ETDEWEB)

Deposition of coal fly ash and potassium sulfate on tubes representative of superheaters and intermediate temperature air heaters at the DOE Coal Fired Flow Facility during a 2000 hour POC test period is herein described. The deposition is unique to this test facility because of the high combustion temperatures and the use of potassium carbonate as the conducting ``seed.`` This seed material is required for coal fired MHD applications as a means to control sulfur dioxide emissions as it combines with the sulfur in coal to form potassium sulfate. Most of the potassium sulfate solids removed are in the form of a fine ash from which potassium can be recovered and recycled. Testing clearly indicated that the majority of ash/seed deposits can be removed by conventional sootblowing. A significant difference in ash removal is the increased volume of deposits, as potassium compounds make up 75% of the total deposits which must be removed for efficient heat transfer. Tube deposits on the heat exchange surfaces in the area of highest gas temperature have been difficult to remove due to the presence of molten potassium sulfate.

Dace, J.F.; Shaver, T.C.

1993-06-01

154

Development of fly ash derived magnetite for coal cleaning  

Energy Technology Data Exchange (ETDEWEB)

Fly ash from at least one major Queensland pulverized fuel power station contains sufficient magnetite to be an economic source of supply for a substantial portion of the state`s coal preparation industry. The use of fly ash derived magnetite (FAM) as an alternative to natural magnetite has potential advantages in terms of lower cost to the end user, greater medium stability at low separation densities and utilization of a waste by-product from coal-fired power generation. The FAM under consideration has a significantly lower density than natural magnetite (4.1 versus 5.0) making it well suited to low density separations where medium stability is critical. Pilot plant and full plant trials have successfully demonstrated stable DM cyclone circuit operation at medium densities between 1.2 and 1.6 RD with acceptable medium differential, sharpness of separation, separation density offset and rinsing efficiency. Although the magnetic susceptibility of FAM is lower than that of high quality natural magnetite, it has been shown by pilot plant and full plant trails that the use of the latest wet drum magnetic separator technology and circuit design will allow acceptable recoveries and concentrate densities to be achieved. This paper presents the results of the principal facets of the development program. Its main outcome has been the successful demonstration of FAM as a viable alternative to natural magnetite in dense medium coal circuits. 10 refs., 3 figs., 1 tab.

Baird, G.A.; Hornsby, D.T.; Lief, H. [Queensland Cement Ltd. (Australia). Pozzolanic Enterprises Pty. Ltd.

1998-12-31

155

Removal of unburned-carbon from fly-ash of bituminous coal by froth flotation  

Energy Technology Data Exchange (ETDEWEB)

One of the most serious problems in utilizing the fly-ash produced from domestic coal-firing power plants is the unburned-carbon contained in the fly-ash. In this study, the effects of frother and collector on the yield, recovery, unburned-carbon rejection percentage, and process efficiency of product (cleaned fly-ash) were examined when conventional froth flotation was applied to reject the unburned-carbon included in the fly-ash of bituminous coal. Also, the ash analysis for both the raw and the cleaned fly-ash was conducted to review the change in the major elements of fly-ash. Experimental results showed that the rejection of the unburned-carbon of the raw fly-ash sample is available up to 92.4% using froth flotation and that the purity of the product (cleaned fly-ash) attains up to 99.4%. (author). 5 refs., 10 tabs.

Son, Sung Geun; Kim, Jung Duk [Korea Institute of Energy Research, Taejon (Korea, Republic of); Park, Byung-Wook [Korea Fly-ash Cement Co. (Korea, Republic of)

1996-09-30

156

Experiments on alkaline addition to coal mine spoil  

Energy Technology Data Exchange (ETDEWEB)

The results of field tests to study acid mine drainage generation under various conditions are described. Effluent chemistry, temperature, gas phase composition, and hydrologic budget were monitored after alkaline addition to test the effectiveness of adding lime kiln flue dust to prevent acid mine drainage. Pyritic shale was the spoil material used. The effluent from treated cells (1.9% S) is of poor quality compared to water from the full scale experiment conducted at the Kauffman surface coal mine (average 0.3% S). Placement of material high in pyrite in concentrated pods needs to be evaluated further. Minimization of oxygen and water access due to compaction of the pyrite material at the mine may be significant. 11 refs., 6 figs., 3 tabs.

Evans, D.R.; Rose, A.W. [Penn State University, University Park, PA (United States). Department of Geosciences

1995-06-01

157

The growth of Agropyron elongatum in an artificial soil mix from coal fly ash and sewage sludge  

Energy Technology Data Exchange (ETDEWEB)

The paper discusses a greenhouse experiment that was performed to evaluate the feasibility of using an artificial soil medium produced from alkaline coal fly ash and sewage sludge for the growth of Agropyron elongatum (tall wheat grass). Sludge was amended with ash at an application rate of 0, 5, 10, 35 and 50% (w/w). Each mixture was the mixed with a loamy soil at either 1:1 or 1:5 (v/v) and incubated under greenhouse conditions for 3 weeks prior to plant growth experiment. Addition of the ash-sludge mixture significantly improved the seedling emergence and dry weight yields of Agropyron. No excessive accumulation of heavy metals was noted owing to the ash-sludge amendment. The increased yield even at a high amendment rate of 35% ash-sludge mixture at 1:1 v/v soil mixing ratio indicates the potential use of the ash-sludge mixture as an artificial soil mix for agricultural use.

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

1997-01-01

158

Trace element geochemistry of feed coal, fly and bottom ashes of Turkish power plants: implications for ash utilisation  

Energy Technology Data Exchange (ETDEWEB)

Recent environmental concern has led to studies of the fate of environmentally sensitive elements (ESEs) during the combustion of coal in power plants. Of particular interest has been the partioning of potentially hazardous trace elements in coal-combustion waste products (fly ash and bottom ash) and in flue gases. This paper reports on a preliminary investigation into the trace element geochemistry of feed coals, bottom ash and fly ash in thirteen power units in Turkey. It concentrates on sixteen trace elements, five of which are of major environmental concern (Be, As, Mo, Pb, and Tl), two of moderate concern (Cu and Zn), three of minor concern (Mn, Co and Ba). Two of the ESEs are radiogenic (Th and U). Ti, Cs, La, and W, which show interesting distributions, are also considered. The approach has been to analyse the feed coals to highlight any significant element enrichment and to carry out mass balance calculations to determine the partioning of elements between bottom and fly ash. Results indicate that solid residues, particularly fly ash may show unusually high concentrations of moderately volatile ESEs such as As, Pb, Tl, Mo, Be and Zn. The use of such enriched fly ash should be treated with caution. 9 refs., 2 figs., 3 tabs.

Gayer, R.A.; Karayigit, A.I.; Goldsmith, S.; Onacak, T.; Rose, M. [Cardiff University, Cardiff (United Kingdom). Dept of Earth Sciences

1998-12-31

159

Ash transformation in suspension fired boilers co-firing coal and straw : Final report, PSO-Eltra 4766  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this literature report is provided a status for the present knowledge level on ash properties when co-firing coal and biomass. The fly ash formed in boilers using co-firing of coal and straw do have a large influence on ash deposit formation, boiler corrosion, fly ash utilization and operation of flue gas cleaning equipment. This survey includes discussions on the inorganic constituents transformation during straw and coal combustion, alkali-ash and alkali sulfur reactions, a survey of pow...

Zheng, Yuanjing; Jensen, Peter Arendt; Jensen, Anker Degn

2011-01-01

160

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 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

2008-02-19

 
 
 
 
161

Resource recovery from coal fly ash waste: an overview study  

Energy Technology Data Exchange (ETDEWEB)

Coal fly ash (CFA) is a useful byproduct of the combustion of coal. It is composed primarily of almost perfectly spherical aluminosilicate glass particles. This spherical characteristic and other characteristics of CFA should be exploited, rather than simply using CFA as inert filler for construction. Unfortunately, the presence of carbon residues and high levels of heavy metals has so far limited the uses of CFA. Forced leaching methods have been used to improve the technical and environmentally friendly qualities of CFA, but these processes do not seem to be economically viable. Actually, CFA is a major source of Si and Al for the synthesis of industrial minerals. Potential novel uses of CFA, e.g., for the synthesis of ceramic materials, ceramic membrane filters, zeolites, and geopolymers, are reviewed in this article with the intention of exploring new areas that will

Kumar, V.; Matsuda, M.; Miyake, M. [Okayama University, Okayama (Japan). Graduate School of Environmental Science

2008-02-15

162

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2011-01-01

163

Worldwide production of coal ash and utilization in concrete and other products  

Energy Technology Data Exchange (ETDEWEB)

This paper summarizes coal ash production and utilization in the world and presents a country-by-country survey of the use of coal ash in concrete. The bulk of the information presented was obtained through a questionnaire sent to selected individuals in 29 countries. 53 refs.,1 tab.

Manz, O.E. [Manz Associates, Alvarado, MN (United States)

1997-06-01

164

Soil stabilization and pavement recycling with self-cementing coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

This manual provides design information for self-cementing coal fly ash as the sole stabilizing agent for a wide range of engineering applications. As in any process, the application of sound engineering practices, appropriate testing, and evaluation of fly ash quality and characteristics will lend themselves to successful projects using the guidelines in this manual. Topics discussed include: self-cementing coal fly ash characteristics; laboratory mix design; stabilization of clay soils; stabilisation of granular materials; construction considerations; high sulfate ash; environmental considerations for fly ash stabilization; design considerations; state specification/guidelines/standards; and a sample of a typical stabilization specification.

NONE

2008-01-15

165

Analysis of fly ash produced from combustion of refuse-derived fuel and coal mixtures  

Energy Technology Data Exchange (ETDEWEB)

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 Ca, Mn, Sb, and Pb to the fly ash while coal contributes greater amounts of As, Br, Hf, Ni, Sc, V, and the rare earths. Smaller particles in the RDF fly ash had higher concentrations of As, Cd, Ga, K, Na, Sb, and the rare earths. RDF fly ash contains four distinct morphologies, exhibits a high specific surface area, and does not resemble fly ash derived from a conventional coal-fired power plant. The morphology of the ash helps explain the high solubility of many species in the RDF-rich fractions.

Taylor, D.R. (Colorado State Univ., Fort Collins); Tompkins, M.A.; Kirton, S.E.; Mauney, T.; Natusch, D.F.S.

1982-03-01

166

Laboratory studies on preparation and utilization of high-ash black coal fines  

Energy Technology Data Exchange (ETDEWEB)

Investigates technological possibilities of processing type 34 non-caking black coal fines with 28.4% ash content. Wet comminution and classification of the coal suspension into 3 fractions (above 0.25 mm, 0.25 to 0.04 mm and less than 0.04 mm) is proposed. The first two fractions show a partial demineralization effect, i.e. 13.3% and 18.1% ash content respectively; the smallest fraction shows an ash content increase to 62.3%. Use of the fraction with 13.3% ash content for coke production in a mixture with 80% regular sized type 34 black coal and use of propane bitumen binder is proposed. The fraction with 18.1% ash content is considered suitable for use in power plants; the ash enriched fraction can be mixed with power plant ash and used as a building material. 8 refs.

Naundorf, W.; Wollenberg, R.

1988-01-01

167

Rapid slurry analysis of solid coal and fly ash samples  

Energy Technology Data Exchange (ETDEWEB)

Coal and coal fly ash samples were analyzed as solid slurries. These preliminary experiments used fast sampling STPF procedures which omitted the pyrolysis step and the matrix modifier. The experiments also used an ultrasonic mixing device that automatically stirred the suspension just before the autosampler probe withdrew the aliquot which it would dispense onto the platform. The combination of these techniques made it possible to reduce the analytical time to less than 1 min per sample. Simple aqueous standards were used for calibration. The NIST SRM 1633a Coal Fly Ash was successfully analyzed for As, Pb and Tl, with results for Se in this material that suggested that more work was required to gain confidence in the determination. The SRM 1632a Coal was successfully analyzed for As and Pb. The methods were the same for both materials. A few mg of the dry solid powder were weighed directly into the autosampler cup followed by a weighed amount (about 1.5 ml) of suspending diluent. The characteristic mass was calculated from several aliquots of simple aqueous standards and this value was used to calculate the amount of analyte delivered to the furnace. In the work reported here the detection limits for the elements determined were about 0.5-1{mu}g/g in the solid sample. With further experience these limits may be improved. The precision for replicates of slurries from the same cup varied from 2 to 10% depending upon the amount of solid sample delivered to the furnace. 17 refs., 6 tabs., 5 figs.

Bradshaw, D.; Slavin, W. (Perkin-Elmer Corporation, Lake Mary, FL (USA))

1989-01-01

168

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)

2008-01-01

169

Operational experience of the RKTP-2 instruments for ash control in a coal stream  

Energy Technology Data Exchange (ETDEWEB)

The design and performance are evaluated of the RKTP-2 gamma ash meter used in coal preparation plants for determining ash content in coal transported on belt conveyors. The system, mounted above a conveyor belt, measures gamma radiation backscattered by a coal layer. Coal layer on a conveyor belt should be not thinner than 150 mm. When the coal layer is thinner than 150 mm, the system supplies inaccurate results as it measures radiation backscattered not only by coal but also by the conveyor belt. Design of the RKTP-2 is shown in 2 schemes. Its installation above a conveyor belt is described. Design of steel elements used for leveling coal on a conveyor belt and for forming a layer at least 150 mm thick is described. When the RKTP-2 is used for determining ash content in coal low in ash, absolute error does not exceed 0.4 or 0.5% ash content. When ash content in coal is high and exceeds 20%, absolute error is higher and ranges from 0.7 to 0.8% ash content.

Starchik, L.P.; Grabov, P.I.; Potapov, A.B.

1984-07-01

170

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)

2001-05-20

171

Chemical speciation of elements in stack-collected, respirable-size, coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

The data reported in this paper effectively complete the description of the chemical speciation of the elements in a set of four stack-collected coal fly ash samples which have been used extensively in the determination of the biological effects of coal fly ash. The association of elements with the aluminosilicate glass or surface salts, the association of cations and anions of the surface of ash particles, and the oxidation states of nonmetal and transition metals are discussed. 27 references.

Hansen, L.D.; Silberman, D.; Fisher, G.L.; Eatough, D.J.

1984-03-01

172

On-site field tests for study of low-rank western coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

This report describes a series of field and laboratory studies of the characteristics and control of fly ash emissions from low-rank Western coals. Field tests were conducted at three pulverized coal-fired utility boilers burning low-rank Western coals. Each field test included: measurements of the mass concentrations of fly ash suspended in the flue gas at the inlet and outlet of the particulate collector and determination of the overall fly ash collection efficiency, measurements of the inlet and outlet particle size distributions of the fly ash and determination of the fractional collection efficiency, measurements of the electrical resistivity of the ash, documentation of the operating conditions of the boiler and the particulate collector, analysis of the important flue gas components, and collection of coal and ash samples for various laboratory studies. The laboratory work that was done in conjunction with each field test included: proximate and ultimate analyses of the coal, chemical analysis of the fly ash, measurements of ash resistivity as a function of temperature and flue gas environment, and detailed microanalytical characterization of individual ash particles. The bulk physical and chemical characteristics of these ashes are described in detail in the report, and microanalytical characterizations of individual ash particles are presented. The latter show some very interesting correlations between elemental composition and particle size and between one element and another. The potential uses of these data are discussed, and areas that require further investigation are identified. It is concluded that the fly ash emissions from low-rank Western coals can be effectively controlled with existing technology if the particulate collector is properly designed and operated; ash resistivity can be predicted; a better understanding of ash-flue gas interactions is needed. 33 references, 46 figures, 17 tables.

Dahlin, R.S.; Marchant, G.H. Jr.; Gooch, J.P.; Bickelhaupt, R.E.; Sears, D.R.

1984-08-01

173

Investigation of the coal fly ashes using IR spectroscopy.  

Science.gov (United States)

The results of FT-IR spectroscopic studies of coal fly ashes, originated from various polish power plants are reported. The results of MIR investigations were compared to the X-ray diffraction (XRD) measurements and chemical analyses. They are mainly composed of silica, alumina and lime. The infrared spectrum in the middle range can be used to describe both the structure of phases present in the fly ash and to identify the characteristic elements of the individual components of ash. The results indicate that the amount of aluminosilicate and its Si/Al ratio induce a shift in the T-O stretching band appearing at 950-1100cm(-1). Moreover, FWHM of these bands indicates the participation of the crystalline phase relative to amorphous. The presence of carbonate phases generates substantial changes in the 1450-1400cm(-1) area of the spectra. The presence of such phases as anhydrite, mullite or illite has also been established on the basis of IR spectra. PMID:24935825

Mozgawa, W; Król, M; Dyczek, J; Deja, J

2014-11-11

174

Uranium content in coal and fly ash samples  

International Nuclear Information System (INIS)

In the present study, we have measured the U-content in coal samples of different collieries used as fuel in Thermal Power Plant, Kasimpur (U.P.) and in the fly ash collected from there. The samples were ground very finely and sieved through a 100 mesh sieve. The sample powder and methyl cellulose powder (a binder free from uranium contamination) were mixed in the ratio 1:2 by weight. Thin pellets of this mixture (? 1.3 cm dia) was made by a hydraulic tablet making machine. These pellets were sandwiched between a pair of washed, cleaned and dried plastic track detector (Makrofol KG). These pellets along with a pellet of standard glass of known U-content were irradiated with a thermal neutron dose of 1015 (nvt) in the 'APSARA' reactor at Bhabha Atomic Research Centre, Bombay. After irradiation the detectors were separated and etched in 6.25M KOH at 80 C for 20 minutes. The resulting tracks were counted. The U-content in coal shows a variation of 1.07 to 6.67 ppm in uniform distribution and 26.82 to 46.74 ppm in non-uniform distribution. In fly ash the U-content varies from 6.83 to 9.48 ppm in uniform and from 51.73 to 64.50 ppm in non-uniform distribution. (author). 5 refs., 2 tabs

1991-10-01

175

Chlorine and ash composition in two Illinois coals and two British coals  

Energy Technology Data Exchange (ETDEWEB)

The high chlorine (Cl) content in British coals has been cited as causing boiler corrosion. However, such a correlation has not been indicated for high-Cl Illinois coals. This may suggest that boiler corrosion is not directly related to the amount of Cl in the coal. Other factors, such as how the Cl occurs in the coal, or, the influence of other substances such as alkali metals and sulfur may be important when evaluating the potential corrosiveness of a coal. In this study, the forms of and the evolution characteristics of Cl and the composition of ash in two Illinois and two British coals were examined. The results of chlorine analyses indicate that the Cl in coal exists in ionic forms, including small amounts of a solid NaCl salt form. When heated under air, Illinois coals released hydrogen chloride gas at higher temperatures with maximum evolution occurring around 425 to 475{degrees}C, whereas, for British coals, the maximum evolution occurred between 210 and 280{degrees}C. The results of ash analyses indicate that British coals contain a higher level of soluble sodium with respect to soluble potassium. The soluble Na to K ratios calculated as oxides on a dry coal basis (Na{sub 2}O/K{sub 2}O) for the British coals were 9.53 and 9.0, whereas, the ratios for the Illinois coals were 1.02 and 2.31. A similar relationship was exhibited for the relative corrosion indices (I{sub c}) calculated according to Borio et al. The I{sub c} values for the British coals were 53.94 and 51.42; for the Illinois coals, the figures were 10.90 and 17.50. However, the soluble Na{sub 2}O measured in this study were higher than the maximum values measured in the Borio`s study and caution should be exercised in interpreting those reported since they constitute an extrapolation outside their original correlation.

Chou, M.-I.M.; Lytle, J.M. [Illinois State Geological Survey, Champaign, IL (United States); Pan, W.P. [Western Kentucky Univ., Bowling Green, KY (United States)] [and others

1995-03-01

176

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

177

Monitor of ash content of coal with X-ray source  

International Nuclear Information System (INIS)

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

1983-06-01

178

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

Directory of Open Access Journals (Sweden)

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

Kisi? Dragica M.

2013-01-01

179

The partitioning behaviour of boron from tourmaline during ashing of coal  

Energy Technology Data Exchange (ETDEWEB)

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

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

2002-12-01

180

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

1984-04-01

 
 
 
 
181

Utilizing ash from power plants fired with brown coal to increase spoil bank stability  

Energy Technology Data Exchange (ETDEWEB)

Fly ash from electrostatic precipitators at the Belchatow power plant was used as a stabilizing additive to sand from spoil banks of the Belchatow surface mine. Fly ash hardening and its dependence on relation of ash to water was analyzed. Compression strength of fly ash after a minimum hardening time was higher that that of soil samples from Belchatow. Mixing fly ash with sand was especially economic. During the experiments sand to fly ash ratio ranged from 1:0.2 to 1:0.5. Fly ash ratio of 1:0.3 was optimum. Compression strength of sand mixed with 30% fly ash exceeded that of sand alone, irrespective of moisture content. Use of fly ash for stabilizing spoil banks consisting of sand from the Belchatow brown coal mine is recommended. 6 refs.

Traczyk, R.

1987-11-01

182

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

183

Rheology of fly ashes from coal and biomass co-combustion  

Energy Technology Data Exchange (ETDEWEB)

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. 38 refs., 8 figs., 2 tabs.

S. Arvelakis; F.J. Frandsen [Technical University of Denmark (DTU), Lyngby (Denmark). CHEC Research Group

2010-10-15

184

Sulphur in the coke and ash of eocene coal and utilisation constraints and prospects  

Energy Technology Data Exchange (ETDEWEB)

The Eocene coal of Bapung Coalfield contains high amount of sulphur with dominant organic fraction. The distribution of sulphur in the coal, coke and ash are assessed for planning the proper use of coal. At high temperature (925 C) a considerable amount of organic sulphur is volatilized leaving the coke suitable for industrial uses. The Bapung coal can be used in blends with Gondwana coal of Bengal-Bihar region for producing metallurgical coke for steel plants. (orig.)

Ahmed, M. [Gauhati Univ. (India). Dept. of Geological Sciences; Rahim, A. [Guwahati Coll. (India). Dept. of Chemistry

1997-12-31

185

Physico-chemical characterization and leaching of desulphurization coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

Fly ash produced by coal combustion using two types of desulphurization process were studied: a conventional pulverized coal boiler equipped with lime injection (PCL ash), and a circulating fluidized bed combustion boiler with limestone injection (CFBC ash). The ashes were characterized completely: granulometry, morphology, mineralogy, chemical composition and behaviour to water contact. Both PCL ash and CFBC ash present similar features: fine granulometry, presence of anhydrite phase and sulphate content. However, PCL ash also shows lots of spherical particles, unlike CFBC ash, and a much higher lime content, due to the lower desulphurization rate in PC boilers. Unlike CFBC ash, most of the trace elements in PCL ash show an inverse concentration-particle size dependence. Leachates obtained from both samples are rich in soluble salts (CaSO{sub 4} and Ca(OH){sub 2}) and arsenic and selenium are prevented from solubilizing by high lime content. In wetted PCL ash, the formation of ettringite crystals stabilizes calcium and sulphur ions. Simultaneously, arsenate, selenate and chromate anions are trapped in the crystal. CFBC ash does not really harden because the lime content is too low. However, the leached selenium concentration is cut down in wetted CFBC ash samples.

Lecuyer, I.; Bicocchi, S.; Ausset, P.; Lefevre, R. [Electricite de France, Chatou (France). Direction des Etudes et Recherches

1996-02-01

186

A study of fluidized bed solids and fly ash samples to better understand the transformations of the coal ash  

Energy Technology Data Exchange (ETDEWEB)

A special fluidized bed combustion technology, developed in Hungary is described. It is called the hybrid-fluid combustion technology, and has been introduced at the Ajka Power Plant where the CaO content of the ash in local coals is high. A thermogravimetric balance and mass spectrometry was used to study the bed solids and fly-ash samples from the hybrid-fluid boiler, in order to understand the connections between sulphur, lime and carbon compounds contents and their reactions.

Remenyi, K.; Horvath, F.

1993-01-01

187

Quantum chemistry calculation and experimental study on coal ash fusion characteristics of coal blend  

Energy Technology Data Exchange (ETDEWEB)

The coal ash fusion characteristics of high fusibility coal blending with two low fusibility coals respectively were studied. The data were analyzed using quantum chemistry methods and experiment from micro-and macro-molecular structures. The results show that Ca{sup 2+}, as the electron acceptor, easily enters into the lattice of mullite, causing a transition from mullite to anorthite. Mullite is much more stable than anorthite. Ca{sup 2+} of anorthite occupies the larger cavities with the (SiO{sub 4}){sup 4-} tetrahedral or (AlO{sub 4}){sup 5-} tetrahedral rings respectively. Ca atom linked O weakens Si-O bond, leading ash fusion point to reduce effectively. The chemistry, reactivity sites and bond-formation characteristics of minerals can well explain the reaction mechanism refractory minerals and flux ash melting process at high temperature. The results of experiment are agreed with the theory analysis by using ternary phase diagrams and quantitative calculation. 27 refs., 9 figs., 3 tabs.

Chen Yushuang; Zhang Zhong-xiao; Wu Xiao-jiang; Li Jie; Guang Rong-qing; Yan Bo [University of Shanghai for Science and Technology, Shanghai (China). Department of Power Engineering

2009-07-01

188

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

1995-11-01

189

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

190

Ash-related problems of slagging and erosion wear in coal-fired boilers  

Energy Technology Data Exchange (ETDEWEB)

The severity of boiler slagging is largely determined by the relative amount of non-silicate minerals, chiefly pyrite, carbonate and chloride species in coal. Fuel-plant wear and tube erosion by ash impaction is related to the amount of abrasive quartz mineral in coal. Cleaning processes designed to reduce sulphur and ash content can significantly alleviate slagging problems. Boiler design and operation measures must ensure that the temperature regime and flue-gas composition are appropriate for the slagging characteristics of the ash deposits, and that the flue-gas velocity is appropriate for the abrasive characteristics of the ash.

Raask, E.

1983-12-01

191

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

192

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

International Nuclear Information System (INIS)

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

1989-01-01

193

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

194

Main characteristics of the radioactive enrichment in ashes produced in coal-fired power stations  

International Nuclear Information System (INIS)

Under contract with the Spain's 'Nuclear Safety Council', a study is being conducted of the nation's largest nominal output coal-fired power stations. Its purpose is to assess the radiological impact on workers and local populations due to this source of NORM activity. One of the aspects of particular interest is the study of the radioactive enrichment in the combustion wastes relative to the different coals used as fuel (usually local bituminous coal or lignite, or imported coal). These wastes consist of fly ash (mostly fine particles collected in electrostatic precipitators), and bottom ash (larger in size, and collected wet or dry in hoppers below the boilers). In general terms, the enrichment factors measured were between 2 and 18 for the radionuclides 40K, 226Ra, 232Th, and 210Po. The magnitude of this enrichment factor depended mainly on the ash content of each coal, and hence on the type of coal used as fuel and the specific operation cycle in the different power stations. For the radionuclides 40K, 226Ra, and 232Th, the enrichment was relatively similar in value in the fly and bottom ashes produced by the different types of coal used in the power stations studied. For 210Po, however, as was expected, the enrichment was much greater in the fly ash than in the bottom ash for each coal analyzed. (author)

2008-10-19

195

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

International Nuclear Information System (INIS)

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

1980-01-01

196

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

International Nuclear Information System (INIS)

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

1984-12-04

197

Coal fly ash and alginate for the removal of heavy metals from aqueous solutions  

Energy Technology Data Exchange (ETDEWEB)

The use of a basic coal fly ash in the removal of heavy metal ions from aqueous solutions has been investigated. It has been shown that the yields depend on ash dosage and metal concentration; the results are generally good and can be improved in some cases by pH lowering. As a matter of fact, fly ash gives a basic pH to the metal solutions; heavy metals are removed principally by precipitation and adsorption on ash particles. The addition of sodium alginate sometimes makes it possible to reach higher yields at alow ash dosage, but its effect must be carefully evaluated in the case of mixed ions.

Ferrero, F.; Prati, M.P.G. [Politecnico di Torino, Torino (Italy). Dipt. di Scienzia Materiali e Ingegneria Chimica

1996-03-01

198

Preparation and characterization of carbon-enriched coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

Carbon-enriched fractions have been obtained from two coal fly ash (FA) samples. The FA came from two pulverized-coal fired power stations (Lada and Escucha, Spain) and were collected from baghouse filters. Sieving was used to obtain carbon-enriched fractions, which were further subjected to two beneficiation processes: acid demineralization using HCl and HF, and oil agglomeration using soya oil-water. Yield in weight after sieving, unburned carbon content, and several physicochemical characteristics, of the obtained fractions were used to compare the performance of the beneficiation methods. Low carbon concentration was obtained by sieving. particularly in the case of Escucha FA. However, after acid demineralization or oil agglomeration, fractions containing unburned carbon in a range of 63% to 68% were obtained. These fractions showed differences in mineral phase composition and distribution depending on the FA and oil the beneficiation method used. The textural properties of the obtained fractions varied as a function of their carbon content and the beneficiation method used. However, no significant differences in morphology of the carbonaceous particles were found

Rubio, B.; Izquierdo, M.T.; Mayoral, M.C.; Bona, M.T.; Martinez-Tarazona, R.M. [CSIC, Zaragoza (Spain)

2008-09-15

199

Fabrication of Test Tubes for Coal Ash Corrosion Testing  

Energy Technology Data Exchange (ETDEWEB)

This paper deals with the fabrication of tube sections of four alloys for incorporating into test sections to be assembled by Babcock & Wilcox (B&W) for installation at Ohio Edison Power, Niles Plant. The primary purpose of the installation was to determine the corrosion behavior of ten different alloys for flue gas corrosion. Ohio Edison Power, Niles Plant is burning an Ohio coal containing approximately 3.4% S (dry basis) and approximately 0.4% alkali which causes chronic coal ash corrosion of the unit?s superheater tubing. The 2.5-in.-OD x 0.4in.-wall x 6-in-long sections of four alloys {type 304H coated with Fe3Al alloy FAS [developed at the Oak Ridge National Laboratory (ORNL)], 310 + Ta, modified 800H, and Thermie alloy} were fabricated at ORNL. Each alloy tubing was characterized in terms of chemical analysis and microstructure. The machined tubes of each of the alloys were inspected and shipped on time for incorporation into the test loop fabricated at B&W. Among the alloys fabricated, Thermie was the hardest to extrude and machine.

Johnson, R.; Judkins, R.R.; Sikka, V.K.; Swindeman, R.W.; Wright, I.G.

1999-05-11

200

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

International Nuclear Information System (INIS)

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

1995-05-01

 
 
 
 
201

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)

2010-01-01

202

Radioactive substances in fly ash from coal-fired power plants  

International Nuclear Information System (INIS)

Coal and fly ash samples from various German coal-fired power plants have been analyzed for 238U, 230Th, 226Ra, 210Pb, 228Th and 228Ra. It is shown, that the specific activity of the fly ash depends much more on the boiler type than on the specific activity of the coal. Characteristic differences were found between dry bottom furnaces and slag tap fired boilers. The enrichment of volatile substances in fly ash collected in the last electrostatic precipitator increases with the furnace temperature and is especially large, if the fly ash is recycled into the body of the furnace for granulation in slag tap fired boilers. Fly ash from such boilers contained up to 6 Bq/g (160 pCi/g) lead 210. (orig.)

1979-01-01

203

2007 American Coal Ash Association membership directory as of June 21, 2007  

Energy Technology Data Exchange (ETDEWEB)

A listing of names, addresses, contact numbers and websites is given for 101 members of the American Coal Ash Association. Honorary members are also named. Included are power generation companies, combustion by-product manufacturers and university departments.

NONE

2007-07-01

204

A review of ash in conventional and advanced coal-based power systems  

Energy Technology Data Exchange (ETDEWEB)

Process conditions are briefly described for conventional and advanced power systems. The advanced systems include both combustion and gasification processes. The authors discuss problems in coal-based power generation systems, including deposition, agglomeration and sintering of bed materials, and ash attack are discussed. They also discuss methods of mitigating ash problems and anticipated changes anticipated in ash use by converting from conventional to advanced systems.

Holcombe, N.T. [Dept. of Energy, Morgantown, WV (United States). Morgantown Energy Technology Center

1995-12-31

205

Beneficial use of coal ash in mine reclamation and mine drainage pollution abatement in Pennsylvania  

Energy Technology Data Exchange (ETDEWEB)

In the United states some 90 million tons of fly ash is produced annually. After briefly describing the chemical composition of pulverised coal fly ash and fluidised bed combustor ash, their use in various case studies in Pennsylvania are given. The case studies cover surface mine reclamation, surface reclamation of deep mine subsidence area, acid mine drainage pollution abatement and prevention, and encapsulation of burial pyritic materials by pressure grouting. 17 refs., 5 tabs.

Scheetz, B.E.; Menghini, M.J.; Hornberger, R.J.; Owen, T.D.; Schueck, J.; Giovannitti, E. [Pennsylvania State University, University Park, PA (United States). Materials Research Lab.

1998-11-01

206

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 pur...

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

2012-01-01

207

Chemical speciation of elements in stack-collected, respirable-size coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

This paper is concerned with the delineation of the chemical speciation of the elements in coal fly ash collected in the stack after the electrostatic precipitator. The association of elements with the aluminosilicate glass or surface salts, the association of cations and anions on the surface of ash particles, and the oxidation states of non-metal and transition metals are discussed.

Hansen. L.D.

1984-03-01

208

Comparison between (n-?), (?-?) and natural ?-ray activity techniques for ash measurement of coal samples  

International Nuclear Information System (INIS)

A comparison between neutron capture gamma (n-?), compton backscattering gamma ray (?-?) and natural radioactivity techniques was performed to measure the ash content of coal samples from coal mines in the north of Iran. The results proved that the neutron-gamma technique is superior to the other two techniques. The standard deviation between the chemical assays and the neutron-gamma, gamma-gamma and natural gamma predictions are 1.44, 5.68 and 1.71% ash, respectively

1999-04-01

209

Implications of power station management, in-vogue boundary-constraints with particular reference to utilise coal-ash, generated by thermal power plants in India, all aiming to draft one pragmatic strategy to use coal-ash more effectively  

Energy Technology Data Exchange (ETDEWEB)

The different types of coal combusted in power plants of different design lead to coal ash of varying quality. A strategy for utilising coal ash more effectively is required. The constraints on obtaining a strategy, and suggestions for a strategy are given.

Roy, S. [Coal Ash Institute of India (India)

1996-12-31

210

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

211

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

212

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.

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

213

A two-step process for the synthesis of zeolites from coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

The conversion of fly ash into zeolites by incubation of the fly ash with alkaline solutions is a well known process which, however, usually results in a zeolitic product which still contains significant amounts of residual fly ash. Presented in the article is a method by which part of the silicon in fly ash can be used for the synthesis of a maximum of 85 g of pure zeolite per kg of fly ash prior to the residual being converted into zeolite by the traditional method. The cation exchange capacities ranged from 3.6 to 4.3 meq/g for the pure zeolites and from 2.0 to 2.5 meq/g for the zeolite containing residual fly ash. Tests showed that the pure zeolites are suitable for the removal of ammonium and heavy metal ions from waste water. 9 refs., 6 figs., 5 tabs.

Hollman, G.G.; Steebrugeen, G.; Janssen-Jurkovicova, M. [Utrecht University, Utrecht (Netherlands). Dept. of Geochemistry

1999-08-01

214

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-11-15

215

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

216

Hyperfine and X-ray studies of coal and coal ash  

International Nuclear Information System (INIS)

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

1993-04-01

217

Brick manufacture with fly ash from Illinois coals. Technical report, March 1, 1995--May 31, 1995  

Energy Technology Data Exchange (ETDEWEB)

This investigation seeks to utilize fly ash in fired-clay products such as building and patio bricks, ceramic blocks, field and sewer tile, and flower pots. This goal is accomplished by 1) one or more plant-scale, 5000-brick tests of fly ash mixed with brick clays at the 20% or higher level; 2) a laboratory-scale study to measure the firing reactions of a range of compositions of clay and fly ash mixtures; 3) a preliminary study to evaluate the potential environmental and economic benefits of brick manufacture with fly ash. Bricks and feed materials will be tested for compliance with market specifications and for leachability of pollutants derived from fly ash. The laboratory study will combine ISGS databases, ICCI-supported characterization methods, and published information to improve predictions of the firing characteristics of Illinois fly ash and brick clay mixtures. Because identical methods are used to test clay firing and coal ash fusion, and because melting mechanisms are the same, improved coal ash fusion predictions are and additional expected result of this research. During this quarter we completed a manufacturing run at Colonial Brick Co. and began laboratory testing of samples from that run: clays, fly ash (from Illinois Power Company`s Wood River plant), and green and fired bricks, with and without fly ash. Bricks with 20% fly ash ``scummed`` during firing, and the fly ash failed to increase oxidation rate or water absorption, which were both expected. We obtained chemical and mineralogical analyses of the fireclays and shales at Colonial and Marseilles Brick Companies and began a series of selective dissolution analyses to more accurately determine the composition of the principal clay minerals in brick clays and the components in fly ash. We began related work of calculating normative mineralogical analyses for all clays and fly ashes that we sample.

Hughes, R.E.; Dreher, G.; Moore, D.; Rostam-Abadi, M. [Illinois State Geological Survey, Urbana, IL (United States); Fiocchi, T. [Illinois Power Co. (United States); Swartz, D. [Colonial Brick Co. (United States)

1995-12-31

218

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

219

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.)

2012-11-01

220

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

International Nuclear Information System (INIS)

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

2009-01-30

 
 
 
 
221

Zeolite formation from coal fly ash and its adsorption potential.  

Science.gov (United States)

The possibility in converting coal fly ash (CFA) to zeolite was evaluated. CFA samples from the local power plant in Prachinburi province, Thailand, were collected during a 3-month time span to account for the inconsistency of the CFA quality, and it was evident that the deviation of the quality of the raw material did not have significant effects on the synthesis. The zeolite product was found to be type X. The most suitable weight ratio of sodium hydroxide (NaOH) to CFA was approximately 2.25, because this gave reasonably high zeolite yield with good cation exchange capacity (CEC). The silica (Si)-to-aluminum (Al) molar ratio of 4.06 yielded the highest crystallinity level for zeolite X at 79% with a CEC of 240 meq/100 g and a surface area of 325 m2/g. Optimal crystallization temperature and time were 90 degrees C and 4 hr, respectively, which gave the highest CEC of approximately 305 meq/100 g. Yields obtained from all experiments were in the range of 50-72%. PMID:19842322

Ruen-ngam, Duangkamol; Rungsuk, Doungmanee; Apiratikul, Ronbanchob; Pavasant, Prasert

2009-10-01

222

Zeolite formation from coal fly ash and its adsorption potential  

Energy Technology Data Exchange (ETDEWEB)

The possibility in converting coal fly ash (CFA) to zeolite was evaluated. CFA samples from the local power plant in Prachinburi province, Thailand, were collected during a 3-month time span to account for the inconsistency of the CFA quality, and it was evident that the deviation of the quality of the raw material did not have significant effects on the synthesis. The zeolite product was found to be type X. The most suitable weight ratio of sodium hydroxide (NaOH) to CFA was approximately 2.25, because this gave reasonably high zeolite yield with good cation exchange capacity (CEC). The silica (Si)-to-aluminum (Al) molar ratio of 4.06 yielded the highest crystallinity level for zeolite X at 79% with a CEC of 240 meq/100 g and a surface area of 325 m{sup 2}/g. Optimal crystallization temperature and time were 90{sup o}C and 4 hr, respectively, which gave the highest CEC of approximately 305 meq/100 g. Yields obtained from all experiments were in the range of 50-72%. 29 refs., 5 tabs., 7 figs.

Duangkamol Ruen-ngam; Doungmanee Rungsuk; Ronbanchob Apiratikul; Prasert Pavasant [Chulalongkorn University, Bangkok (Thailand). Department of Chemical Engineering

2009-10-15

223

Low temperature catalytic oxidation of hydrogen sulfide and methanethiol using wood and coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

The research compared the catalytic oxidation potential of coal and wood fly ash, determined the kinetics of H{sub 2}S and methanethiol oxidation and decay, determined a potential mechanism for the catalysis, and studied a method to regenerate the catalyst. Coal ash from a process utilizing selective catalytic reduction via NH{sub 3} injection for NOx removal and wood ash from a pulp mill was used in this study. Activated charcoal was also tested for direct comparison to the fly ash. Results suggest that coal fly ash and to a much greater extent wood ash has the potential to replace activated carbon as a low cost catalyst for removal of H{sub 2}S from high volume, low concentration streams. The adsorption capacity and reaction rate of wood ash for H{sub 2}S, although lower than activated carbon, is within an acceptable range for low concentration applications such as wastewater treatment facilities, combined use with biofiltration to treat sulfur gas mixtures, and pulp and paper facilities. Hydrogen sulfide conversions remained {gt} 94% for 4 days using wood ash at inlet concentrations typical of many environmental applications and if combined with a continuous regeneration process may lead to a low cost reaction/adsorption process. 25 refs., 6 figs., 2 tabs.

Kastner, J.R.; Das, K.C.; Buquoi, Q.; Melear, N.D. [University of Georgia, Athens, GA (USA). Dept. of Biological and Agricultural Engineering, Driftmier Engineering Center

2003-06-01

224

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

International Nuclear Information System (INIS)

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

1985-01-01

225

Studies on the potential of coal fly ash as a heterogeneous catalyst in oxidation of aqueous sodium sulfide solutions with hydrogen peroxide  

Energy Technology Data Exchange (ETDEWEB)

The potential use of fly ash procured from coal-fired thermal power plants as a heterogeneous catalyst in the oxidation of aqueous sodium sulfide solutions with hydrogen peroxide in the temperature rage of 303-323 K was investigated. The effects of various parameters (source of fly ash fly ash loading, initial concentrations of sodium sulfide and hydrogen peroxide, electrolyte and catalysts deactivation were studied). For an initial sodium sulfide and hydrogen peroxide concentration of 26.98 x 10{sup -2}, kmol m{sup -3} and 24.28 x 10{sup -2} kmol m{sup -3} respectively, only 4% (w/v) fly ash loading intensified the rate of oxidation by a factor of 4.52 over that without fly ash at 303 K. The deactivation of the catalytic effect of fly ash was found to be less than 20% even after six repeated uses. The kinetics of aqueous phase decomposition of hydrogen peroxide was also studied in the presence of fly ash in alkaline medium.

Mallick, D.; Khanra, S.; Chaudhuri, S.K. [University of Calcutta, Calcutta (India). Dept. of Chemical Engineering

1997-11-01

226

Slaking the lime remaining in the partially desulphurated ashes from a coal fired boiler  

Energy Technology Data Exchange (ETDEWEB)

This Thermie Clean Coal Technology project (Project no. SF/134/90/FR) has developed an hydration process for upgrading ash, which has a high lime content and sulphate content, so it can be used as a cement additive. The CERCHAR hydration process was developed at the pulverised coal-fired Provence power station, located in Gardanne, France. 1 fig., 5 photos.

NONE

2000-07-01

227

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 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)

2012-01-01

228

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

International Nuclear Information System (INIS)

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

1982-08-18

229

Testing the application of portable scintillation unit HOU 22 SCS in determining ash content in coal  

International Nuclear Information System (INIS)

Operating tests were conducted for determining the ash content of coal on the conveyor belt using a portable scintillation radiometric unit of the HOU22 SCS type. The apparatus operated on the principle of scattered gamma radiation from a 75Se source with an activity of 18 MBq. The detection probe 41 mm in diameter was mounted at the inlet of the coal flow onto the conveyor belt. The accuracy of determination of the ash content of undersize coal used for power production (grain size 0 to 10 mm) was +-4.4%. (B.S.)

1977-12-01

230

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

231

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)

2013-01-01

232

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

Directory of Open Access Journals (Sweden)

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

Kovács Ferenc

2002-09-01

233

Study of radon exhalation rate and uranium concentration from fly ash produced in the combustion of coal using SSNTD's  

International Nuclear Information System (INIS)

Fly ash is the end product of coal combustion and coal. Like most earthen materials it contains 238U the parent element of the uranium decay series which support several radioactive decay products including radon. Radon exhalation rate from fly ash produced by thermal power station has been measured and compared with that from different kinds of soil and from coal itself. It is observed that the radon exhalation rate from fly ash is less than that from soil and coal, although fly ash contains a higher concentration of uranium than typical soil. (author)

2005-07-01

234

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

235

Preparation of low-ash products from Slovak lignitic coals – material balance  

Directory of Open Access Journals (Sweden)

Full Text Available A preparation of low-ash coal products was performed with the aim to obtain asuitable charge for the extraction following processes of organic substances. Thus, for this purpose, the coal feeds from two collieries, namely Záhorie and Nováky were washed in the water-only cyclone with a diameter of 150 mm. The vortex finder and apex diameters were 68 mm and 14.6 mm, respectively. The cone consisting of three angle sections 135°-75°-20° was applied. The products obtained on the overflow of the cyclone were decantated to remove the rests of slurries. In such a way, washed coals with the ash content in the dry matter of 5.44 was prepared from lignite of Záhorie. Similarly, as to coal from Nováky the ash content of 9.21 % was achieved.

Anton Zubrík

2006-12-01

236

Controlling effects of ash, total sulphur and chemical forms of sulphur in coals on the selection of components of coal blends for making metallurgical cokes  

Energy Technology Data Exchange (ETDEWEB)

This paper investigates the possibility of utilizing coals of high ash and sulphur contents in making cokes of metallurgical quality. Lafia coal used in this study had earlier been found on laboratory scale to be suitable as a bridging coal between non-coking Enugu coal and a prime coking coal in a blend for making metallurgical coke. Because the sulphur and ash contents of Lafia coal are high, coupled with the fact that the sulphur occurs in mainly pyritic form with the pyrites finely disseminated within the vitrinite, coke made from blends containing this coal exhibit high ash and sulphur contents. In this study, Enugu coal of low ash and relatively low sulphur content, containing most of the sulphur in the organic form, and Gaully Eagle coking coal of lower ash and lower sulphur, having almost all the sulphur in the organic form have been co-carbonished with Lafia coal in blends of varying ratios. The ash and sulphur contents of the cokes from the blends were determined in an effort to study the effect of changes in the percentage of each of Enugu and Gaully Eagle coals on the ash and sulphur contents of the cokes. Results show that ash and sulphur contents of the cokes decrease with increase in percentage of each of Enugu and Gaully Eagle coals in the blend. However, the effect is more pronounced with Gaully Eagle than with Enugu coal. This laboratory exercise suggests that appreciable amounts of coal of high ash and high pyritic sulphur can be utilized in blends for making metallurgical cokes provided that other components of the blend are low in ash and sulphur with the sulphur occurring in predominantly organic form. 18 refs., 10 figs., 2 tabs.

Ndaji, F.E.; Imobighe, G.A.

1989-01-01

237

Pair production for on-line determination of ash in coal  

International Nuclear Information System (INIS)

The ash content of coal can be determined by a technique based on the simultaneous measurement of 0.511 MeV annihilation radiation and Compton scattered radiation which result from irradiation of a coal sample with ?-rays of energy > 1.022 MeV. The pair production (PP) technique has been proved on bulk samples of brown coal and occurring for the first time on a steel armored conveyor belt. (author)

1987-09-21

238

Coal Ash Resources Research Consortium. Annual report and selected publications, 1 July 1992--30 June 1993  

Energy Technology Data Exchange (ETDEWEB)

The Coal Ash Resources Research Consortium (CARRC, pronounced cars), formerly the Western Fly Ash Research, Development, and Data Center (WFARDDC), has continued fundamental and applied scientific and engineering research focused on promoting environmentally safe, economical use of coal combustion fly ash. The research tasks selected for the year included: (1) Coal Ash Properties Database Maintenance and Expansion, (2) Investigation of the High-Volume Use of Fly Ash for Flowable Backfill Applications, (3) Investigation of Hydrated Mineralogical Phases in Coal Combustion By-Products, (4) Comparison of Department of Transportation Specifications for Coal Ash Utilization, (5) Comparative Leaching Study of Coal Combustion By-Products and Competing Construction Materials, (6) Application of CCSEM for Coal Ash Characterization, (7) Determination of Types and Causes of Efflorescence in Regional Concrete Products, and (8) Sulfate Resistance of Fly Ash Concrete: A Literature Review and Evaluation of Research Priorities. The assembly of a database of information on coal fly ash has been a focus area for CARRC since its beginning in 1985. This year, CARRC members received an updated run time version of the Coal Ash Properties Database (CAPD) on computer disk for their use. The new, user-friendly database management format was developed over the year to facilitate the use of CAPD by members as well as CARRC researchers. It is anticipated that this direct access to CAPD by members as well as CARRC researchers. It is anticipated that this direct access to CAPD by members will be beneficial to each company`s utilization efforts, to CARRC, and to the coal ash industry in general. Many additions and improvements were made to CAPD during the year, and a three-year plan for computer database and modeling related to coal ash utilization was developed to guide both the database effort and the research effort.

Pflughoeft-Hassett, D.F.; Dockter, B.A.; Eylands, K.E.; Hassett, D.J.; O`Leary, E.M.

1994-04-01

239

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

240

COM fuel based on Hokkaido coal (II): the effect of ash in Sunagawa coal COM as judged from flow curves  

Energy Technology Data Exchange (ETDEWEB)

Measurements of flow characteristics were used to investigate the effects of ash content in coal on the dispersibility of COM. After an anionic surfactant had been added, increasing the ash content strengthened the thixotropic properties of the COM, raised the yield value and increased the tendency to gelate. It was discovered that these phenomena were intensified by addition of polyvinyl alcohol (PVA) as a stabilizer. (4 refs.)

Enomoto, Y.; Akama, A.; Morimoto, S.; Matsubara, M.

1982-01-01

 
 
 
 
241

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)

1981-01-01

242

Speciation of Chromium in Feed Coals and Ash Byproducts from Canadian Power Plants Burning Subbituminous and Bituminous Coals  

Energy Technology Data Exchange (ETDEWEB)

The chromium species in the feed coals and ash byproducts from seven Canadian coal-fired power plants that were burning local subbituminous or bituminous coals with sulfur contents in the range of 0.30-3.5 wt % have been examined using Cr X-ray absorption near-edge spectroscopy (XANES). Chromium in the Canadian feed coals is always found as Cr{sup 3+} but generally has a dual occurrence, as Cr{sup 3+} is distributed to varying degrees between the clay mineral illite (Cr3+/illite) and a poorly crystallized chromium oxyhydroxide (CrOOH) phase associated with the organic fraction. In two subbituminous feed coals from Alberta, chromium is present largely as Cr{sup 3+}/illite, whereas in two other such coals, it is present predominantly as CrOOH. Chromium in a low-sulfur (0.50 wt %) bituminous feed coal from Alberta is found mostly as Cr{sup 3+}/illite, whereas for feed coals from Nova Scotia with high sulfur contents (2.60-3.56 wt %), chromium is distributed between both Cr{sup 3+}/illite and CrOOH. Very little chromium was found in the limestone used in a fluidized-bed combustor. The chromium species in most bottom ash samples from all seven combustion units is predominantly, if not entirely (>95%), Cr{sup 3+} associated with aluminosilicate phases. Chromium speciation for subbituminous electrostatic precipitator (ESP) fly ash is mostly Cr{sup 3+} (>95%), but in some cases, it is slightly less (>80%) and varies by sampling location at the plant. Chromium in fly ash from the combustion of bituminous feed coals is predominantly (>95%) Cr3+. A unique species of chromium found in one feed coal and an unrelated fly ash is metallic chromium (Cr0), similar to that in stainless steel. The occurrence of this form of chromium in these materials indicates contamination from machinery, such as the coal milling machine or possibly wearing down of stainless steel parts by the coal or ash. The observation of this unexpected contamination demonstrates the power and usefulness of X-ray absorption fine-structure (XAFS) spectroscopy for speciation determination.

Goodarzi,F.; Huggins, F.

2005-01-01

243

An economic study of clean coal with 34% ash content vis-a-vis raw coal (unwashed) and imported coal for power generation in India  

Energy Technology Data Exchange (ETDEWEB)

The Chari Committee submitted its report to Planning Commission in 1996, in which a comparison had been made on the economics of the use of imported coal versus F grade coal from Kalinga opencast mine of Talcher coalfield, by Tamil Nadu State Electricity Board at its power station located in Chennai. In this paper, with relevant change in that report with respect to present situation, the elements of cost of washed coal by beneficiation of F grade coal to the level of 34% ash has been revised. This study has been done to draw a comparison of clean coal with 34% ash content (washery at power plant end) vis-a-vis raw coal (unwashed) and imported coal regarding the cost of generating 1 kWh energy, taking into account all the factors. 2 refs., 6 tabs.

Mukhopadhyay, S. [B.E. College (Deemed University), Howrah (India). Dept. of Mining and Geology

2003-02-01

244

Catalytic effects of brown coal ash components during gasification of soft brown coal, Part 3: Study of brown coal from East of the river Elbe  

Energy Technology Data Exchange (ETDEWEB)

Analyzes gasification velocity of brown coal from 8 GDR surface mines with varyingly catalytic active ash content in coal. Laboratory gasification was carried out either by carbon dioxide or steam. Brown coal ash content was between 3.8 and 7.0%, calcium content between 0.7 and 2.0%. A Polish brown coal with high aluminium content and a saliniferous brown coal with 1.44% sodium content were also studied for comparison. Analysis results are provided in graphs. Gasification velocity was correlated with element content. Accurate correlations were obtained for gasification velocity and calcium, sodium and iron content, applying carbon dioxide gasification. Correlations for steam gasification were in general less favorable, circulation gas desulfurization was required. Best correlations obtained in steam gasification were noted for gasification velocity and a coal with calcium and magnesium content and another coal with calcium, sodium and iron content. 6 refs.

Koepsel, R.; Zabawski, H. (Bergakademie, Freiberg (German Democratic Republic))

1989-01-01

245

Coal ash usage in environmental restoration at the Hanford site  

Energy Technology Data Exchange (ETDEWEB)

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

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

1994-08-01

246

Study on improving effect of classified fly ash on concrete using coal ash and crushed sand; Fly ash ni yoru sekitanbai to saisa wo mochiita concrete no kairyo koka ni kansuru kenkyu  

Energy Technology Data Exchange (ETDEWEB)

The past studies have revealed that concrete using crushed sand, of which about 10% is displaced with coal ash, can improve the particle size constitution, reduces water required for mixing producing denser concrete, and increases strength as a result of the Pozzolan reaction. Discussions were given on effect of improving quality of the concrete using coal ash and crushed sand by mixing coal ash having further finer particle size (classified flyash: CFA) into the concrete using the coal ash and crushed sand. The concrete having the coal ash displaced at 20% against the crushed sand and the CFA at 10% against the coal ash had the compression strength increased by about 30% at the material age of 180 days as compared with a case without displacements. On the other hand, concrete whose part of the crushed sand displaced with coal ash and CFA may have inferior long-term strength depending on weather conditions under exposed condition. Displacing the crush sand with coal ash and/or CFA slightly reduces drying contraction, and improves durability against hydrochloric acid. 18 figs., 6 tabs.

Terada, D.; Ikeda, R. [Chugoku Electric Power Co. Inc., Hiroshima (Japan)

1998-08-25

247

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

International Nuclear Information System (INIS)

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

1986-01-01

248

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1995-12-31

249

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

250

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

251

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

International Nuclear Information System (INIS)

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

1999-01-15

252

Cenosphere-load in coal-ash discharge of thermal power plant  

International Nuclear Information System (INIS)

Cenospheres present in coal-ash are hallow solids, light in nature. During the sluicing of the ash-discharge of thermal power plant these cenospheres float on the surface, adding significantly to the load of suspended solid in the ash-pond effluents. The proportion of the cenospheres in coal-ash discharge of thermal power plant at Korba (MP) has been determined, and found to be several times higher than those reported abroad. Concentrations of a large number of toxic metals (Cu, Co, Ni, Pb, Mn, Zn, Cd, Mo, V, Cr, Sn, Be) have been determined in the cenosphere samples. The environmental aspects of the presence of cenosphere have been discussed. (author). 10 refs., 1 tab

1993-06-01

253

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1997-04-28

254

Seasonal variations of metals in coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

Seasonal variations in fly ash collected from the electrostatic precipitator of a thermal power plant in New Delhi, over a period of twelve months were studied for the following parameters; particle size; per cent silicate; haemolysis; variations in the concentration of seventeen metal ions in the fly ash. 16 references.

Srivastava, V.K.; Srivastava, P.K.; Kumar, R.; Misra, U.K.

1986-01-01

255

Iron speciation in coal fly ashes—chemical and Mössbauer analysis  

Science.gov (United States)

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

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

2013-11-01

256

Iron speciation in coal fly ashes—chemical and Mössbauer analysis  

Science.gov (United States)

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

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

2014-04-01

257

Ash chemistry and mineralogy of an Indonesian coal during combustion: Part II - Pilot scale observations  

Energy Technology Data Exchange (ETDEWEB)

This paper reports on combustion experiments carried out in a pilot scale furnace as a follow-up to research previously carried out using a drop-tube furnace to investigate the combustion behaviour of an Indonesian coal, in particular the effects of additives on ash chemistry, mineralogy and ash deposit formation. Combustion experiments were carried out in a pilot scale furnace to test the effectiveness of bauxite addition in reducing ash build-up. Samples collected from deposits on the slagging panels and fouling probe tubes, electrostatic precipitator fly ash, the furnace ash and tunnel ash were fully characterized using various analytical techniques. Experimental results substantiated earlier drop-tube observations suggesting that the use of raw coal with an addition of 3 wt.% bauxite would appear to offer the best performance with respect to slagging and fouling propensity in comparison to use of the raw coal alone. Observations on the reduction in glass content resulting from the addition of bauxite during PSF test runs support the earlier findings of the drop-tube tests. The reduction in glass content found in the slagging panel and fouling probe samples is comparable to that found in ash formation experiments conducted at 1400 C despite the observed differences in mineralogy. Although deposits are still likely to form as indicated by the PSF runs they appear to be more friable and hence amenable to removal by conventional methods such as frequent soot blowing. These findings demonstrate how the results of laboratory experiments can be combined with those of pilot scale trials to provide data for full-scale trials on the effects of additives in the remediation of ash problems associated with the firing low-rank coals. (author)

Vuthaluru, H.B. [Department of Chemical Engineering, Curtin University of Technology, Kent Street, Bentley, Perth Western Australia 6102 (Australia); French, D. [CSIRO Energy Technology, Lucas Heights Science and Technology Centre, Private Mail Bag 7, Bangor New South Wales 2234 (Australia)

2008-06-15

258

[Determination of 12 elements in coal ash by x-ray fluorescence spectrometry].  

Science.gov (United States)

A method for the determination of SiO2, Al2O3, Fe2O3, CaO, SO3, TiO2, K2O, Na2O, P2O5, MgO, MnO and BaO in coal ash by X-ray fluorescence spectrometry with melt sample preparation was developed. This method solved the problems of determination accuracy of S by using the 12:22 mix flux and oxide to lower the melt temperature. Using the soil standard sample and mixing the soil standard sample and coal ash standard sample solved the problem that there are not enough standard samples for coal ash analysis by XRF. The accuracy and precision of this method are acceptable, and the results are comparable to the those obtained by wet chemical method. PMID:18800742

Song, Yi; Guo, Fen; Gu, Song-hai

2008-06-01

259

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

Science.gov (United States)

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

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

2013-07-01

260

Ash-related problems of slagging and erosion wear in coal-fired boilers by E Raask  

Energy Technology Data Exchange (ETDEWEB)

The severity of boiler slagging is largely determined by the relative amount of non-silicate minerals, chiefly pyrite carbonate and chloride species in coal. The fuel-plant wear and tube erosion by ash impaction is related to the amount of abrasive quartz mineral in coal. Cleaning processes designed to reduce the sulphur and ash content of coal would significantly alleviate the slagging problems. The boiler-design and operation measures must ensure that the temperature regime and flue-gas composition are appropriate for the slagging characteristics of the ash deposits, and that the flue-gas velocity is appropriate for the abrasive characteristics of ash.

Raask, E.

1983-12-01

 
 
 
 
261

Effects of the use of coal ash in heavy, cohesive soils (I): improvement of the physical properties of soil  

Energy Technology Data Exchange (ETDEWEB)

A study is reported of the effectiveness of coal ash for improving the physical properties of heavy, cohesive soils and for obtaining better quality Japanese radishes. Radishes were grown in four different soil types (the original heavy soil as a control, plus three coal ash and soil mixtures with different ash mixing ratios). A study was then made of soil reactions and phase distributions, the yield and quality of the radishes grown, their transpiration, and changes in soil moisture content. It is concluded that the use of coal ash in such soils can improve the quality of radishes and increase the available moisture in the soil. 2 references.

Nakajima, Y.; Matsui, M.

1984-01-01

262

Nuclear techniques for the on-line determination of the ash content of coal on conveyors and in slurries  

International Nuclear Information System (INIS)

This paper investigates potential applications of the use of low energy ?-ray techniques to determine directly on-line the ash content of coal as it passes source-detector systems mounted about plant conveyors. It also proposes a method for determination of the ash content of coal in slurries which is insensitive to variations of voidage of the slurries

1981-01-01

263

Growth of crops in soil with coal ash additions (II): the growth of various vegetables in volcanic ash soil and their absorption of inorganic constituents  

Energy Technology Data Exchange (ETDEWEB)

With the aim of utilizing pulverized coal combustion ash (obtained from coal-fired power stations) as a soil improver for agricultural land, potatoes, spinach, Japanese radishes and soya beans were grown in volcanic ash soil with up to 50% coal ash admixture. At mixing ratios of 10-30%, soil pH, EC and concentrations of Ca and B increased, and faster growth and greater yields of crops were obtained. This improvement is thought to be due to the addition of coal ash resulting in 1) adjustment of soil pH level, 2) accelerated absorption of elements essential to growth (B, Mo) and 3) an increase in the available moisture. 32 references.

Okabe, K.; Aoki, M.; Ogawa, T.; Misonoh, J.; Nakaoka, A.; Fukushima, M.

1985-01-01

264

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

International Nuclear Information System (INIS)

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

1992-01-01

265

Upgrading of coal ashes and desulphurisation residues to provide high value products  

Energy Technology Data Exchange (ETDEWEB)

Mitsui Babcock Energy Limited, Technology Centre have co-ordinated a collaborative project whose aim has been to investigate the possibility of preparing ettringite-based products and calcium sulphoaluminate cements from coal ashes and sulphoaluminate cements from coal ashes and desulphurisation residues. The results show that ettringite based plasters prepared using fly ash and gypsum exhibited poor mechanical strengths and unacceptable drying shrinkage. The ettringate produced was unstable. Laboratory synthesis of CSA binders using blends of gypsum or spray dry desulphurisation residue (calcium sulphite), calcium carbonate and fly ashes (including those with high unburned carbon contents)is possible at temperatures in the range 1200 - 1250{degree}C. Mortars prepared using the best CSA binder and tested according to ENV 197-1 (1996) yielded compressive strengths of 4, 6 and 12 MPa at 2, 7 and 28 days respectively. CSA-based binders have the potential for use as blended cements with OPC or as replacements for OPC in special ateas of application. If the feed mixture composition and process parameters are optimised, it is likely that significant improvements in properties can be made. Comparison of costs indicated that the CAS binder production process was the most cost effective method for disposal of waste coal ashes and desulphurisation residues. profits were more than 100 percent higher than for thermal upgrading of high carbon ashes, which could provide attractive income streams for electricity generators. A commercialisation strategy for CSA cements has been developed. 2 figs.; 10 tabs.

Fitzgerald, F.D.; Repetto, F.; Calabro, B.; Heijnen, W.M.M.; Larbi, J.A. [Mitsui Babcock Energy Limited, Renfrew (United Kingdom)

1999-07-01

266

Desulphurization Characteristic of Industry Alkaline Wastes during Coal Combustion  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 c...

Bin Zheng; Chunmei Lu

2009-01-01

267

Utilization of the power station by-product brown coal fly ash; Verwendung des Kraftwerksnebenprodukts Braunkohlenfilterasche  

Energy Technology Data Exchange (ETDEWEB)

After approval of brown coal fly ash as an additive for concrete in accordance with Standard DIN 1045 and its utilization as specified in DIN EN 450, this product will have to face competition from a product that has been on the market for many years. Nor will a reliable quality-guarantee system and extensive references facilitate the introduction of brown coal fly ash products on the market. Viewed from a long-term aspect, the utilization of brown coal fly ash must therefore not be confined to the role of additive for concrete, but the established binder properties of this ash must be taken into account as a qualitative increase in comparison with hard coal fly ash. To this end, tests were carried out on ash blends as specified in the Cement Test Standard. These tests revealed that the technical properties of building materials, such as standard consistency, commencement of setting process, end of setting process and constancy of volume, as determined for brown coal fly ash, comply with the requirements specified in DIN EN 196. On the other hand, the research results achieved at the Technical University of Cottbus show that there are ways and means of forecasting certain reaction processes of a brown coal fly ash which make it possible to utilize the binder properties of the different types of brown coal fly ash systematically and consistently to advantage and in this way achieve specific target hardnesses. (orig.) [Deutsch] Nach Zulassung der BFA als Betonzusatzstoff nach DIN 1045 und Verwendung nach der DIN EN 450 wird dieses Produkt auf ein langjaehrig auf den Markt eingefuehrtes, konkurierendes Produkt treffen. Ein solides Qualitaetssicherungssystem und umfangreiche Referenzen fuer diese Produkte werden die Markteinfuehrung einer BFA nicht erleichtern. Laengerfristig darf sich deshalb der Einsatz der BFA nicht nur auf den Bereich als Betonzusatzstoff beschraenken, sondern es muessen die bekannten Bindemittel-Eigenschaften der BFA als qualitative Steigerung im Vergleich zur SFA beruecksichtigt werden. Dazu wurden Untersuchungen von Aschegemischen nach der Zementpruefnorm durchgefuehrt. Diese Versuche ergaben, dass sich die baustofftechnischen Eigenschaften Normsteife, Erstarrungsbeginn, Erstarrungsende und Raumbestaendigkeit innerhalb der Forderungen der DIN EN 196 bewegen. Andererseits zeigen die Forschungsergebnisse an der BTU Cottbus, dass es Moeglichkeiten einer Vorhersage bestimmter Reaktionsablaeufe einer BFA gibt, die es gestatten, zielgerichtet die Bindemitteleigenschaften der verschiedenen BFA konsequent auszunutzen und bestimmte Zielfestigkeiten zu erreichen. (orig.)

Huenger, K.J.; Sickert, S. [TU Cottbus (Germany). Lehrstuhl Baustoffe/Bauchemie

1998-03-01

268

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2005-03-01

269

Coal fly ash exposure at agronomic levels does not induce triploidy in maize  

Energy Technology Data Exchange (ETDEWEB)

Coal fly ash from fossil-fuel power plants is a major waste disposal problem in the USA. It has been proposed as a soil amendment, as it contains minerals such as sulphur and boron which are beneficial to plants, however other trace minerals are potentially harmful and could have subtle genotoxic effects. A previous laboratory study had revealed triploidy in maize grain on soil containing fly ash additives, in this study fly ash from the Central Illinois Public Service power plant was mixed with growing medium and the growth of maize kernels in it monitored. No excess number of triploids was noted. The conclusions from this study are that the fly ash used caused no incidence of polyploidy in the first generation, although some other fly ashes may be genotoxic. 15 refs., 1 fig., 1 tab.

Taets, C.; Rayburn, A.L. [University of Illinois, Urbana, IL (United States). Dept. of Crop Sciences

1996-05-01

270

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

Energy Technology Data Exchange (ETDEWEB)

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.

Ctvrtnickova, T.; Mateo, M.P.; Yanez, A.; Nicolas, G. [University of La Coruna, La Coruna (Spain)

2010-08-15

271

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

Science.gov (United States)

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.

Ctvrtnickova, T.; Mateo, M. P.; Yañez, A.; Nicolas, G.

2010-08-01

272

Scandium in the composition of ash wastes of Ehckibastuz coals (according neutron activation measurement results)  

International Nuclear Information System (INIS)

The results of neutron-activation analysis (NAA) of ash wastes of the Ehckibastuz coals, selected at the periphery of the Reftinsk ash dump are discussed. Activation of specially prepared and standard samples was accomplished in the nuclear reactor channel at the Beloyarskaya NPP. Registration of gamma-radiation spectra of activated samples was performed by means of the Ge-Li semiconducting detector coupled with a multichannel analyzer. The average Sc content in the samples of the Reftinsk ash dump constituted with an account of systematic and random errors 35.3±1.6 g/t

1995-01-01

273

Radiometric method for the continuous determination of the ash content of low-grade coals  

International Nuclear Information System (INIS)

A radiometric method and apparatus have been developed for the continuous determination of the ash content of low-grade coals. The apparatus can be used for continuous measurements in an industrial environment and for the control of an automatic system. The material to be tested is continuously delivered by a screw-feeder through the measuring compartment of the radiometric probe. The ash content determination is based on gamma absorption measurement. Making use of the incrementof gamma reflection the radiometric method allows for the accurate determination of the space-filling and provides for the automatic correction necessary for the ash content determination. (author)

1980-11-05

274

Radiometric determination of ash content of coal with variable chemical composition  

International Nuclear Information System (INIS)

The first part of the paper contains a review of the well knows radiometric methods of determining the ash content of coal, as well as the techniques for overcoming interferences due to variations of iron content. The advantages of the intrinsic compensation method with the use of "2"3"8Pu source, are shown. The experimental results concerning the other sources of errors, in particular grain size and water content effects, are presented. Precision, accuracy and possibilities of applying suggested method for rapid control of the ash content of coal in industry, are discussed. (author)

1978-01-01

275

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

International Nuclear Information System (INIS)

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

1976-01-01

276

Adsorption of Rhodococcus Strain GIN-1 (NCIMB 40340) on Titanium Dioxide and Coal Fly Ash Particles  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Rhodococcus strain GIN-1 (NCIMB 40340) can be used to enrich and isolate a titanium-rich fraction from coal fly ash. The gram-positive bacterium was isolated by its ability to adhere strongly and rapidly to suspended particles of pure titanium dioxide or coal fly ash. Adsorption depends on the salt concentration and occurs in seawater. Lowering of the salt concentration or washing of particles with pure water did not, however, cause desorption of the bacteria from TiO2 particles; this was ach...

Shabtai, Y.; Fleminger, G.

1994-01-01

277

Characteristics variation of coal combustion residues in an Indian ash pond  

Energy Technology Data Exchange (ETDEWEB)

Coal-fired power plants all over the world are cited as one of the major sources that generate huge quantities of coal combustion residues (CCRs) as solid wastes. Most frequently CCRs are collected through electrostatic precipitators, mixed with bottom ash by hydraulic systems and deposited in ash ponds. The quality of the CCRs at different locations in one of the ash ponds in Central India was evaluated to understand the variation in characteristics with a view to effective utilization. Results revealed that the presence of fine particles ({lt}50{mu}m) increased with increasing distance from the ash slurry inlet zone in the ash pond. Wide variations in the bulk density (800-980 kg m{sup -3}), porosity (45-57%) and water-holding capacity (57.5-75.7%) of CCRs were recorded. With increasing distance the pH of the CCRs decreased (from 9.0 to 8.2) and electrical conductivity increased (from 0.25 to 0.65 dS m{sup -1}). The presence of almost all the heavy metals in CCRs exhibited an increase with distance from the ash slurry discharge zone due to the increase in surface area (from 0.1038 to 2.3076 m{sup 2} g{sup -1}) of CCRs particles. The present paper describes the variation of characteristics of CCRs deposited in the ash pond and their potential applications.

Asokan, P.; Saxena, M.; Aparna, A.; Asoletar, S.R. [CSIR, Bhopal (India). Regional Research Lab.

2004-08-01

278

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

279

Manipulation of gasification coal feed in order to increase the ash fusion temperature of the coal to operate the gasifiers at higher temperatures / Johannes Chrisstoffel van Dyk  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Coal is a crucial feedstock for South Africa's unique synfuels and petrochemicals industry and used by Sasol as a feedstock to produce synthesis gas via the Sasol-Lurgi Fixed Bed Dry Bottom (FBDB) gasification process. The ash fusion temperature (AFT) gives detail information on the suitability of a coal source for gasification purposes, and specifically to the extent ash agglomeration or clinkering is likely to occur within the gasifier. Ash clinkering inside the gasifier can cause channel b...

2006-01-01

280

Determination of cadmium, mercury and lead in coal fly ash by slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry  

Energy Technology Data Exchange (ETDEWEB)

Ultrasonic slurry sampling electrothermal vaporization isotope dilution inductively coupled plasma mass spectrometry (USS-ETV-ID-ICP-MS) was used to the determine Cd, Hg and Pb in coal fly ash samples. Thioacetamide (TAC) was the modifier. Since the sensitivities of the elements studied in coal fly ash slurry and aqueous solution were quite different, isotope dilution method was used for the determination of Cd, Hg and Pb in the coal fly ash samples. The isotope ratios of each element were calculated from the peak areas of each injection peak. This method was applied to the determination of Cd, Hg and Pb in NIST SRM 1633a coal fly ash reference material and a coal fly ash sample collected from Kaohsiung area. Detection limits estimated from standard addition curves were in the range of 24-58, 6-28 and 108-110 ng g{sup -1} for Cd, Hg and Pb, respectively.

Liao, H.C.; Jiang, S.J. [National Sun Yat Sen University, Kaohsiung (Taiwan). Dept. of Chemistry

1999-08-09

 
 
 
 
281

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

International Nuclear Information System (INIS)

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

1987-01-01

282

Surface tension measurements of coal ash slags under reducing conditions at atmospheric pressure  

Energy Technology Data Exchange (ETDEWEB)

The global demand for reduced CO{sub 2} emission from power plants can be answered by coal gasification techniques. To develop integrated gasification combined cycles that incorporate hot syngas cleaning facilities, detailed knowledge of the thermophysical properties of coal ashes is imperative. Currently, the surface tension of liquid coal ash slags in a reducing environment was studied by means of the sessile drop method. Three different algorithms were employed to analyze the acquired drop images. The slags under consideration were obtained from black and brown coals as well as from an experimental gasification reactor. Typically, a sharp surface tension decrease with temperature was found in the melting interval of the ashes. This was followed by a temperature range of smooth drop contours during which a slight rise of the surface tension could mostly be observed. Bubbles at the circumference of the drops started to appear when approaching the measurement temperature limit of 1550{sup o}C. With regard to the temperature regime of uncorrugated drop profiles, coal ash slags exhibited surface tension values between 400 and 700 mN/m. 32 refs., 9 figs., 1 tab.

Tobias Melchior; Gunther Putz; Michael Mueller [Forschungszentrum Juelich GmbH, Juelich (Germany). Institute of Energy Research

2009-09-15

283

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

2013-01-01

284

Effects of degree of ash removal from coal extracts on performance of a catalyst used in hydrogenation  

Energy Technology Data Exchange (ETDEWEB)

Ash effects in coal extracts on catalyst performance during hydrogenation are analyzed. Three coal extracts were used: extract with ash content reduced to 0.36% by filtration, extract with ash content reduced to 1.75% by sedimentation and extract with original ash content of 3.84%. The nr. 201/05 catalyst (nickel, molybdenum, cobalt and aluminium oxide) developed in Poland was used on a steady bed in hydrogenation. Flowsheets of the hydrogenation system are given. Hydrogenation effects are shown in 5 diagrams and in 1 table. Catalyst performance was assessed by determining conversion degree of the residue fraction with boiling point exceeding 445 C, components insoluble in benzene, asphaltenes, as well as by determining hydrogen volume supplied to the system. Investigations showed that ash content in coal extracts significantly influenced catalyst performance. Coal extracts with ash content exceeding 0.5% blocked the active centers of the catalyst within a relatively short time. Therefore extracts with ash content exceeding 0.5% should not have been used in hydrogenation. When ash content was reduced to below 0.5% catalyst life increased. Per each 0.1% ash content decrease, catalyst life increased several times. Reducing ash content in coal concentrates to 0.1-0.2% was sufficient for efficient hydrogenation and guaranteed high catalyst performance. 16 references.

Surygala, J.; Rusin, E.; Pietrzok, B.

1983-08-01

285

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

Energy Technology Data Exchange (ETDEWEB)

Straw may be used today as a substitute fuel to lower the greenhouse gas emissions from traditional coal-fired power plants and provide green-based electricity. It may also provide an alternative source of income to the local farmers helping the developed countries to support sustainable development. The use of straw as a co-firing feedstock in traditional coal-fired plants is associated with operational problems, such as deposition, agglomeration, and/or corrosion, mainly because of the higher amounts of alkali metals and chlorine in straw compared to coal. This may lead to unscheduled shutdowns and costly repairs, increasing the operational costs and the cost of the produced power. In this paper, the melting characteristics of several ash fractions sampled from different parts of a pilot-scale pulverized fuel (PF) boiler operating with different coal/straw mixtures is determined by measuring the ash viscosity using a high-temperature rotational viscometer. The produced data provide information on the melting of the ash material, its flow characteristics, and the rates of crystallization and recrystallization, as a function of the temperature. This information may be used to modify the temperature profile in the different parts of the boiler to reduce the deposition of the ash material. The results show that the straw in the co-combustion mixture changes the viscosity characteristics of the produced ash fractions. The viscosity of the different ash fractions is lowered, as the percentage of straw in the co-combustion mixture increases, and leads to higher stickiness of the produced ash particles at lower temperatures. 25 refs., 4 figs., 3 tabs.

S. Arvelakis; F.J. Frandsen [Technical University of Denmark (DTU), Lyngby (Denmark). CHEC Research Centre

2007-09-15

286

Development of plasma spray coating using coal ash  

Energy Technology Data Exchange (ETDEWEB)

In India about 70 million tonnes of fly ash is generated annually and the figure is growing at a faster rate due to industrial and urban demand. Worldwide, fly ash is being used to generate value added products. In India about 10% of fly ash generated is utilised and if feverish activity is not initiated the percent utilisation can go down. The present piece of work has been undertaken to use the fly ash and graphite (from the rejected electrodes of arc furnaces) for developing plasma spray composite coating on metal substrates. Fly ash and graphite powder (at 10% and 20% wt) mix was plasma sprayed at various operating conditions of the plasma torch on different metal substrate, viz. copper and stainless steel. The coating thus formed was characterised by X-ray diffraction analysis, electron microscopy, microhardness measurement and measurement of interface adhesion strength. A maximum coating thickness of {approximately} 220 micron is obtained with fly ash +20% graphite. The adherence strength is found to vary between 10-35 MNm{sup 2} and is maximum in case of copper substrates. 8 refs., 4 figs., 1 tab.

Mishra, S.C.; Sarkar, P.C.; Mishra, P.C.; Sreekumar, K.P.; Padmanabhan, P.V.A. [Regional Engineering College, Rourkela (India)

2000-07-01

287

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

288

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 met...

2010-01-01

289

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

Energy Technology Data Exchange (ETDEWEB)

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

Wong, J.W.C.; Jiang, R.F.; Su, D.C. [Hong Kong Baptist University, Kowloon Tong (China). Dept. of Biology

1998-08-01

290

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

International Nuclear Information System (INIS)

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

1998-08-01

291

Fast neutron activation analysis of brown coal samples for silica and ash  

International Nuclear Information System (INIS)

The fast neutron activation technique was applied to bulk samples of brown coal. The determination of silicon is based on the reaction 28Si(n,p) 28Al by counting the 1.78 MeV pulses (t1/2 = 2.3 min). The influence from the thermal neutron reaction 27Al(n,?) 28Al is reduced by a Cd-metal shielding which surrounds the sample holder. The ash content determination is based on the correlation between the ash and silica content or between the ash and the sum of the aluminia and silica contents. In the second case the measurement is accomplished without Cd-shielding. The accuracies (1 S.D) of the silica and ash content determination were 0.15 % SiO2, 0.56 % ash and 3.2 % ash for silica and ash contents of the samples in the range of 0.1 - 4 %, 5 - 17 % and 12 - 81 % ash, respectively. (author)

1985-09-23

292

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-11-15

293

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

294

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

295

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

296

Influence of the calcium content on the coal fly ash features in some innovative applications  

Energy Technology Data Exchange (ETDEWEB)

Fly ash showing sharply alkaline reaction usually is high-calcium ({gt} 3-4%), most of which is present as CaO. This is suitable for use as remotion agents of heavy metals in wastewater or retentive agents of them polluted solids. Fly ash giving substantially neutral reaction is usually low-calcium (0-3%) and is suitable for conversion by hydrothermal treatments into zeolitic products, where higher calcium contents interfere. A reverse destination is destitute of good results. Causes are discussed. 23 refs.

Catalfamo, P.; Di Pasquale, S.; Corigliano, F.; Mavilia, L. [Universita di Messina, Sant` Agata di Messina (Italy). Dipartimento di Chimica Industriale

1997-06-01

297

Microspherical inorganic ion-exchangers based on cenospheres of coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

Coal fly ash cenospheres are very promising for a variety of applications, such as production of porous materials, sensitisers of emulsion explosives, adsorbents, catalysts, etc. One of the interesting areas of cenosphere application is generation of microspherical ion-exchangers for immobilization of liquid radioactive waste, which are active in trapping radionuclides from radioactive solutions and, at a final step, can serve as a matrix for radionuclide disposal in the form of stable mineral-like compounds. It was demonstrated that two types of microspherical ion-exchangers, such as (I) encapsulated inorganic ion-exchangers and (ii) cenosphere-derived zeolites, could be prepared on cenospheres. It was shown that chemical modification of cenospheres by etching with mineral acids results in formation of open pores in the cenosphere wall. Depending on the nature of acid, one can obtain hollow microspheres with porous walls of different specific surface area (30-50 m{sup 2}/g for HCl etched cenospheres and 1-2 m{sup 2}/g for HF etched ones) and morphology. Cenosphere species with a macroporous permeable wall is a suitable support for encapsulation of active additives inside the perforated spheres. In this work a number of encapsulated sorbents of {sup 137}Cs{sup +}, such as ammonium molybdophosphate, copper, nickel and iron-ferrocyanides, zirconium phosphate, were obtained. Cenosphere-derived zeolites of NaP, NaX and NaA types were obtained by the hydrothermal treatment of cenospheres in the presence of alkaline solutions. Properties of the encapsulated ion-exchangers and microspherical zeolites were studied in Cs{sup +} and Sr{sup 2+} sorption from simulant solutions of different composition. Sorbents impregnated with radionuclides were shown to convert into stable crystalline compounds under thermal and thermobaric treatment. 19 refs., 5 figs., 3 tabs.

T.A. Vereshchagina; E.V. Fomenko; S.N. Vereshchagin; N.N. Shishkina; N.G. Vasilieva; E.N. Paretskov; D.M. Kruchek; T.J. Tranter; A.G. Anshits [Institute of Chemistry and Chemical Technology SB RAS, Krasnoyarsk (Russian Federation)

2005-07-01

298

Natural radioactivity of ash and coal in major thermal power plants of West Bengal, India  

Energy Technology Data Exchange (ETDEWEB)

Natural radioactivity due to the presence of U-238, Th-232 and K-40 in ash and coal in major thermal power plants of West Bengal, namely Kolaghat, Durgapur and Bandel, has been measured by a NaI (Ti)-based gamma ray spectrometer. The average activity concentrations of the radioelements U-218, Th-212 and K-40 in the ashes of Kolaghat were found to be 111, 140 and 351 Bq/kg respectively, at Durgapur 97, 107 and 315 Bq/kg respectively, and at Bandel 106, 126 and 321 Bq/kg respectively. The absorbed gamma doses in air due to naturally occurring radionuclides in the ash from the power plants varied from 123 to 150 nGy h{sup -1}, which are higher than three times the world average of about 43 nGy h{sup -1}. The ash from power plants contains 2 to 3 times more natural radionuclides than that in feed coal. Ash samples have radium equivalent activity (Ra{sub eq}) and external hazards index (H{sub ex}) values closest to 370 Bq/kg and unity respectively, which have implications in terms of radiation hazard arising due to the use of these ash samples in building and construction.

Mondal, T.; Sengupta, D.; Mandal, A. [Indian Institute of Technology, Kharagpur (India). Dept. of Geology & Geophysics

2006-11-25

299

Aluminum recovery from coal fly ash by high temperature chlorination  

Energy Technology Data Exchange (ETDEWEB)

A study of aluminum recovery from power plant fly ash by high temperature chlorination was undertaken to demonstrate that fly ash could be a potential source of aluminum, iron and possibly silicon. Magnetic separation of the iron oxide served as a first step to alleviate the iron contamination problem. However, the agglomeration of some iron oxide with alumina and silica made it difficult to completely separate the iron from the fly ash. Further iron separation was achieved by chlorinating the nonmagnetic ash fraction at 550/sup 0/C for 30 minutes. This reduced the iron oxide content to less than 4 percent by weight. Chlorine flow rates affected the reaction rate much more drastically than temperatures. This suggested that diffusion was the major rate-controlling step. Besides Fe/sub 2/O/sub 3/, Al/sub 2/O/sub 3/ and SiO/sub 2/, other oxides such as CaO, K/sub 2/O, Na/sub 2/O and MgO might have complicated the alumina recovery by forming individual chlorides or complexes. Investigating methods for separating more Fe/sub 2/O/sub 3/, and possibly CaO, K/sub 2/O, Na/sub 2/O and MgO from the nonmagnetic ash fraction before chlorinating it is highly recommended.

Wijatno, H.

1977-10-01

300

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.

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

 
 
 
 
301

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

Directory of Open Access Journals (Sweden)

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

302

Code making of automatic measurement for coal ash content using annihilation radiation  

International Nuclear Information System (INIS)

In order to realize automatic measurement the Multichannel Computer Analyzer codes were made. This work directly supported the job of determination of ash content of coal using annihilation radiation. The code could not be copied by others and could kill virus by itself. It could be widely used in works of using Multichannel computer Analyzer

1998-09-16

303

Synthesis and physical properties of zeolite from coal ash and its application for environmental protection  

Energy Technology Data Exchange (ETDEWEB)

The hydrothermal synthesis of zeolites from coal fly ash was carried out using NaOH and KOH as an alkali source. The cation exchange properties and the simultaneous removal of NH{sub 4}{sup +} and PO{sub 4}{sup 3-} were investigated for the zeolites thus obtained from coal fly ash. The effective use of these zeolites was evaluated from the viewpoint of environmental protection. Na type zeolite P (NaP) and potassium-chabazite (K-CHA) are mainly formed as zeolite species in NaOH and KOH solutions at 393K. CaP zeolite (CaP) with high substitution percent can be obtained by Ca substitution operation from NaP. As indicated by the X-ray diffraction intensities, NaP, CaP and K-CHA deteriorate with a decrease in pH by acid dissolution of zeolite crystals, when they are used as a cation exchange material. The CaP can simultaneously remove NH{sub 4}{sup +} and PO{sub 4}{sup 3-} in aqueous solution. The zeolite obtained from coal ash can be used as the material for cation exchange and soil improvement, an environmentally friendly use of coal fly ash.

Shibata, J.; Murayama, N.; Matsumoto, S.; Yajima, M.; Yamamoto, H. [Kansai University, Osaka (Japan). Faculty of Engineering

2005-10-15

304

Predictions of radiative properties of pulverized coal and fly-ash polydispersions  

Energy Technology Data Exchange (ETDEWEB)

Radiative properties for polydispersions of carbon, coals (anthracite, bituminous, lignite) and fly-ash are predicted using Mie theory for spherical, homogeneous particles. The spectral extinction and absorption coefficients are calculated for different particle size distribution functions. The extinction coefficient and the single-scattering albedo were found to be rather insensitive to the size distribution. 36 refs.

Viskanta, R.; Ungan, A.; Menguc, M.P.

1981-01-01

305

EFFECTS OF THE DISPOSAL OF COAL WASTE AND ASHES IN OPEN PITS  

Science.gov (United States)

The objective of this study was to determine the extent of groundwater quality deterioration when coal mine solid waste (refuse) and power plant ashes were disposed of into open pits. In addition, disposal methods were developed and procedures for planning and designing disposal ...

306

UTILIZATION OF FLY ASH AND COAL MINE REFUSE AS A ROAD BASE MATERIAL  

Science.gov (United States)

The U.S. Environmental Protection Agency conducted a four-year study to determine the feasibility of using fly ash and coal mine refuse as a road base in a parking lot. The lot was divided into three areas each receiving the same surface treatment but wit different ratios of fly ...

307

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.)

2002-03-01

308

Solvent extraction of molybdenum from biological samples and from coal fly ash for neutron activation analysis  

Energy Technology Data Exchange (ETDEWEB)

A technique has been developed for the determination of Mo in natural water with dithiocarbamate extraction for neutron activation analysis. This paper shows the results obtained by extending the technique to Mo determination in biological samples and in coal fly ash.

Mok, W.M.

1984-11-01

309

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2012-01-01

310

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1982-01-01

311

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

2005-02-28

312

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

313

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

Energy Technology Data Exchange (ETDEWEB)

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

314

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

Energy Technology Data Exchange (ETDEWEB)

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

Kruse, C.W.

1991-12-31

315

Sulphur capturing by an inertinite rich high ash bituminous coal during conversion in a pilot packed bed reactor  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Sulphur is liberated from the coal structure and released in various forms during coal thermal processing. The possibility of sulphur capture, through injection of SO2 into a packed coal bed in a pilot packed bed reactor operated under controlled conditions, was investigated. Results showed that SO2 injection into a packed coal bed leads to sulphur capturing mainly in the coal mineral matter. Mineralogical analysis (XRD) of the ash samples obtained from the experiments indicates that the sulp...

2011-01-01

316

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2000-08-01

317

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

Directory of Open Access Journals (Sweden)

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

Syed Javid Ahmad Andrabi

2013-02-01

318

Determination of solids weight fraction and ash content of coal in slurries of variable voidage: laboratory measurements  

International Nuclear Information System (INIS)

Nuclear techniques have been used to determine the solids weight fraction (W) and ash content of (fine) coal in slurries independent of voidage. The basis of the techniques is the correlation between W and the hydrogen concentration (w/w) of the slurry. At constant ash content, W is determined by combining neutron moderation and ?-ray transmission (density) measurements. With varying ash content, both W and ash content of coal are determined by combining the above measurements with either of two well-established techniques for the determination of ash content of dry coal, namely x-ray backscatter compensated by iron K x-ray excitation, and low energy ?-ray transmission. Radioisotope source and detector were incorporated into three probes which were immersed directly into coal slurry in a 200 L drum. Measurements were made on coal slurries with W in the range 5-22 wt%, ash in coal 20.7-30 wt%, and voidage 0-4 vol.%. The r.m.s. difference W determined by probe measurements and W obtained from assay of slurry samples was 0.54 wt%, a factor of five better than that obtained from the ?-ray transmission (density) measurement alone. The r.m.s. difference for ash content, based on the x-ray backscatter method combined with neutron and ?-ray (density) count rates, was 0.78 wt% ash. (author)

1985-01-01

319

Volatilisation of alkali and alkaline earth metals during the pyrolysis of Loy Yang coal  

Energy Technology Data Exchange (ETDEWEB)

One of the most prominent features of Victorian brown coals is the presence pf significant amounts of alkali and alkaline earth metals (AAEM). These cations, particularly Na{sup +} are responsible for the fouling and slagging problems during the pulverised fuel combustion of these coals at high temperatures. These metals can also contribute to defluidisation when the brown coals are burned/gasified in a fluidised-bed reactor and may also cause problems in gas turbines. The AAEM species partitioned in the volatiles may have different fates and roles from those in the char. Understanding the partitioned mechanisms during pyrolysis is essential for the successful development of new power generation technologies using brown coals. This paper reports some of the authorsexperimental results on the roles and fates of AAEM cations during pyrolysis. 6 refs., 3 figs., 3 tabs.

Pang, Y.; Sathe, C.; Li, C.-Z, [Monash University, Clayton, Vic. (Australia). Dept. of Chemical Engineering, CRC for New Technologies for Power Generation from Low-Rank Coal

1998-12-31

320

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

1995-01-01

 
 
 
 
321

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

International Nuclear Information System (INIS)

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

1992-01-01

322

Developing a coal quality expert: The prediction of ash deposit effects on boiler performance  

Energy Technology Data Exchange (ETDEWEB)

The overall objective of the Coal Quality Expert (CQE) Clean Coal I Program is the development of a Coal Quality Expert -- a comprehensive PC based expert system for evaluating the potential for coal cleaning, blending and switching options to reduce emissions while producing the lowest cost electricity. A key part of the CQE model will be the development of a sub-model to predict the effects of ash deposition on boiler performance under various operating conditions. To facilitate sub-model development, a combination of full, pilot, and bench scale testing has been carried out on a series of coals and coal blends which were of interest to the Public Service of Oklahoma (PSO) at their Northeastern Station. A series of full-scale tests were also performed on PSO's Northeastern Unit {number sign}4 to characterize boiler performance when firing a baseline coal'' (their normal or desired fuel feed stock) and two blends comprised of the baseline coal blended with various amounts of an alternate coal. Actual furnace conditions were then closely matched during a series of tests performed in Combustion Engineering's pilot scale combustor, the Fireside Performance Test Facility (FPTF). Pilot scale testing allowed in-depth analyses of furnace deposits during and after formation under well-controlled conditions. Ash deposit properties were characterized during pilot scale furnace operation and in subsequent bench scale analyses. Determination of deposit behavior as a function of important operating parameters during the FPTF testing has permitted the prediction of expected performance for various coal/coal blends in PSO's Northeastern Units and allows a prediction of boiler performance for other units firing these fuels.

Thornock, D.E.; Borio, R.W. (ABB/Combustion Engineering, Inc., Windsor, CT (United States)); Mehta, A.K. (Electric Power Research Inst., Palo Alto, CA (United States))

1991-01-01

323

Phosphorus Treated Coal Combustion Products (CCP-bottom ash) as an Agricultural Source of Phosphorus  

Science.gov (United States)

Coal combustion products (CCP or "ash") have been seen to be beneficial for improving soil quality and increasing vegetative yields. Owing to their structure with more holes, they are also potential carriers of plant nutrients. The bottom ash from the Lambton Generating Station, Sarnia, Ontario, Canada was treated for 66 hours in 0.10 mol/L P solutions prepared from NaH 2PO 4, which resulted in the ash adsorbing 784 µg/g of phosphorus. The ash was mixed with quartz sand and/or non P-loaded ash from the same source to provide a set of growth media that contained 10%, 25%, 50%, 75%, and 100% of the recommended dose of P (50 µg/g) for maize. Biomass yields at 26, 34, and 46 days after planting were compared with control (non-doped ash) and fertilized with 0-20-0 fertilizer. In general, growth media containing between 25% and 100% of the recommended P dose performed as well or better than the fertilized trials. 46 days after planting, the shoot fresh weight for the 50%, 75%, and 100% doped media were 39.46%, 42.73%, and 46.13%, respectively, greater compared to fertilized trials. The shoot dry weight increased by 29.71%, 13.39%, and 28.87%, respectively. Also, root fresh and dry weight increased averagely by 16.62% and 14.03%. These results implied that coal ashes are a better carrier for P uptaking, and P-loaded ash can be a good additive for sand soil improvement.

Junfeng, Shen; Powell, M. A.; Hayden, D. B.

324

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...

2012-01-01

325

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 ...

326

Control of ash content in coal from the C/O ratio using pulse neutron source  

International Nuclear Information System (INIS)

A method for determination of the ash content in coal in large bulks in one measurement cycle from the ratio of intensities of #betta#-radiation of fast neutron inelastic scattering on nuclei of carbon and oxygen has been considered. The experiments have been conducted using an installation comprising a neutron generator of IGM-4 type on the basis of a neutron tube UNG-1. The #betta#-radiation spectrum has been measured using a pulse analyzer of AI-4096-3M type. It is shown that when the ash content in coal is determined according to the method described, the sensitivity increases. The given method is applicable for coal or metallurgical fuel control in large bulks

1982-01-01

327

An attempt to evaluate some regression models used for radiometric ash determination in the brown coal  

International Nuclear Information System (INIS)

Five different regression models for determination of the ash as well as iron and calcium contents in brown coal using fluorescence and scattering of X-rays have been evaluated. Calculations were done using experimental results obtained from the natural brown coal samples to which appropriate quantities of iron, calcium and silicon oxides were added. The secondary radiation was excited by Pu-238 source and detected by X-ray argone filled proportional counter. The investigation has shown the superiority of the multiparametric models over the radiometric ash determination in the pit-coal applying aluminium filter for the correction of the influence of iron content on the intensity of scattered radiation. Standard error of estimation for the best algorithm is about three time smaler than that for algorithm simulating application of the aluminium filter. Statistical parameters of the considered algorithm were reviewed and discussed. (author)

1984-01-01

328

Coal fly ash utilization: Low temperature sintering of wall tiles  

Energy Technology Data Exchange (ETDEWEB)

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 the manufacturing. The sintering of fly ash with SHMP in the temperature range 925-1050{sup o}C produces tiles with low impact strength; however, the incremental addition of low alkali pyrophyllite improves impact strength. The impact strength of composites with {ge} 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-AlPO{sub 4} phase. Scanning electron micrographs show that the reinforcing rod shaped T-AlPO{sub 4} crystals become more prominent as the pyrophyllite content increases in the sintered tiles.

Chandra, N.; Sharma, P.; Pashkov, G.L.; Voskresenskaya, E.N.; Amritphale, S.S.; Baghel, N.S. [CSIR, Bhopal (India). Regional Research Laboratory

2008-07-01

329

Coal fly ash utilization: low temperature sintering of wall tiles.  

Science.gov (United States)

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 degrees C produces tiles with low impact strength; however, the incremental addition of low alkali pyrophyllite improves impact strength. The impact strength of composites with >or=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-AlPO(4) phase. Scanning electron micrographs show that the reinforcing rod shaped T-AlPO(4) crystals become more prominent as the pyrophyllite content increases in the sintered tiles. PMID:17950591

Chandra, Navin; Sharma, Priya; Pashkov, G L; Voskresenskaya, E N; Amritphale, S S; Baghel, Narendra S

2008-01-01

330

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

2008-01-01

331

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

332

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

International Nuclear Information System (INIS)

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

2012-02-15

333

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

Science.gov (United States)

Coal derived nano-particles has been received much concern recently around the world for their adverse effects on human health and the environment during their utilization. In this investigation the mineral matter present in some industrially important Indian coals and their ash samples are addressed. Coal and fly ash samples from the coal-based captive power plant in Meghalaya (India) were collected for different characterization and nano-mineralogy studies. An integrated application of advanced characterization techniques such as X-ray diffraction (XRD), High Resolution-Transmission Electron microscopy (HR-TEM)/(Energy Dispersive Spectroscopy) EDS/(selected-area diffraction pattern) SAED, Field Emission-Scanning Electron Microscopy (FE-SEM)/EDS analysis, and Mössbauer spectroscopy were used to know their extent of risks to the human health when present in coal and fly ash. The study has revealed that the coals contain mainly clay minerals, whilst glass fragments, spinel, quartz, and other minerals in lesser quantities were found to be present in the coal fly ash. Fly ash carbons were present as chars. Indian coal fly ash also found to contain nanominerals and ultrafine particles. The coal-fired power plants are observed to be the largest anthropogenic source of Hg emitted to the atmosphere and expected to increase its production in near future years. The Multi Walled Carbon Nano-Tubes (MWCNTs) are detected in our fly ashes, which contains residual carbonaceous matter responsible for the Hg capture/encapsulation. This detailed investigation on the inter-relationship between the minerals present in the samples and their ash components will also be useful for fulfilling the clean coal technology principles. PMID:24121564

Oliveira, Marcos L S; Marostega, Fabiane; Taffarel, Silvio R; Saikia, Binoy K; Waanders, Frans B; DaBoit, Kátia; Baruah, Bimala P; Silva, Luis F O

2014-01-15

334

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

Directory of Open Access Journals (Sweden)

Full Text Available

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

335

Coal fly ash-slag-based geopolymers: microstructure and metal leaching.  

Science.gov (United States)

This study deals with the use of fly ash as a starting material for geopolymeric matrices. The leachable concentrations of geopolymers were compared with those of the starting fly ash to evaluate the retention of potentially harmful elements within the geopolymer matrix. Geopolymer matrices give rise to a leaching scenario characterised by a highly alkaline environment, which inhibits the leaching of heavy metals but may enhance the mobilization of certain oxyanionic species. Thus, fly ash-based geopolymers were found to immobilize a number of trace pollutants such as Be, Bi, Cd, Co, Cr, Cu, Nb, Ni, Pb, Sn, Th, U, Y, Zr and rare earth elements. However, the leachable levels of elements occurring in their oxyanionic form such as As, B, Mo, Se, V and W were increased after geopolymerization. This suggests that an optimal dosage, synthesis and curing conditions are essential in order to obtain a long-term stable final product that ensures an efficient physical encapsulation. PMID:19118943

Izquierdo, Maria; Querol, Xavier; Davidovits, Joseph; Antenucci, Diano; Nugteren, Henk; Fernández-Pereira, Constantino

2009-07-15

336

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-07-15

337

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

338

Pulverized coal combustion fly ash penetration through the laboratory scale electrostatic precipitators  

Energy Technology Data Exchange (ETDEWEB)

Laboratory scale set-up including a laminar flow combustion reactor and laboratory scale electrostatic precipitator (LESP), has been constructed to study the effect of coal properties, combustion conditions and ESP operating parameters on fly ash penetration. LESP design was based on the experience achieved in the real scale ESP studies at 300 MW power plant (Ylatalo et al. 1993). Laminar flow reactor as combustion aerosol generator is operated in flow range 60 to 100 lpm to burn pulverised coal particles. The flue gases are cooled and fed into the LESP. In order to avoid corner effects, electric field inhomogenities as well as to keep the flow velocity in industrial range from 0.5 to 1.5 m/s the LESP was designed with tubular geometry and the experiments are carried out in several temperatures between 20-150 C. Fly ash penetration results will be presented as well as size distributions before and after the LESP in the size range 0.01-1=B5m as determined by differential mobility analyser (DMA) and condensation nucleus counter (CNC). We shall present VI-curve results and sub micron number size distributions at the inlet and outlet of the LESP as well as the collection efficiency in several temperatures and electrohydrodynamic numbers for one coal ashes in comparison with the design and laboratory measurements. The penetration of submicron fly ash particles will be studied as the function of the LESP operation conditions.

Ylatalo, S.I.; Kauppinen, E.I.

1995-12-31

339

Catalytic oxidation of gaseous reduced sulfur compounds using coal fly ash  

International Nuclear Information System (INIS)

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

2002-11-11

340

Mixtures of coal ash and compost as substrates for highbush blueberry  

Energy Technology Data Exchange (ETDEWEB)

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

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

2002-07-01

 
 
 
 
341

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 "2"3"8U and "2"2"6Ra 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 m"3 the concentration of Radon in the air will be about 10"-"9 ?Ci/cm"3. 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/cm"3. It is pointed out that if a 25% porosity were used, the Radon concentration will be an order of magnitude higher. (U.K.)

1980-01-01

342

Immobilization of heavy metals in polluted soils by the addition of zeolitic material synthesized from coal fly ash  

Energy Technology Data Exchange (ETDEWEB)

The use of zeolitic material synthesized from coal fly ash for the immobilization of pollutants in contaminated soils was investigated in experimental plots in the Guadiamar Valley (SW Spain). This area was affected by a pyrite slurry spill in April 1998. Although reclamation activities were completed in a few months, residual pyrite slurry mixed with soil accounted for relatively high leachable levels of trace elements such as Zn, Pb, As, Cu, Sb, Co, Tl and Cd. Phytoremediation strategies were adopted for the final recovery of the polluted soils. The immobilization of metals had previously been undertaken to avoid leaching processes and the consequent groundwater pollution. To this end, 1100 kg of high NaPl (Na{sub 6}(AlO{sub 2}){sub 6}(SiO{sub 2}){sub 10}{center_dot} 15H{sub 2}O) zeolitic material was synthesized using fly ash from the Teruel power plant (NE Spain), in a 10 m{sup 3} reactor. This zeolitic material was manually applied using different doses (10000-25000 kg per hectare), into the 25 cm topsoil. Another plot (control) was maintained without zeolite. Sampling was carried out 1 and 2 years after the zeolite addition. The results show that the zeolitic material considerably decreases the leaching of Cd, Co, Cu, Ni, and Zn. The sorption of metals in soil clay minerals (illite) proved to be the main cause contributing to the immobilization of these pollutants. This sorption could be a consequence of the rise in pH from 3.3 to 7.6 owing to the alkalinity of the zeolitic material added (caused by traces of free lime in the fly ash, or residual NaOH from synthesis).

Querol, X.; Alastuey, A.; Moreno, N.; Alvarez-Ayuso, E.; Garcia-Sanchez, A.; Cama, J.; Ayora, C.; Simon, M. [CSIC, Barcelona (Spain)

2006-01-01

343

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 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)

2010-01-01

344

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 H<...

Shunsuke Kashiwakura; Yuichi Kumagai; Hiroshi Kubo; Kazuaki Wagatsuma

2013-01-01

345

Effects of particle size and moisture content on the emanation of Rn from coal ash  

International Nuclear Information System (INIS)

Measurements of the emanation coefficients of "2"2"2Rn from coal ash were performed. Samples of coal ash from a stoker-fired furnace were mechanically sized into four categories. The mean "2"2"6Ra concentration of these categories ranged from 11.82-16.77 dpm g-1 and increased as a function of decreasing particle size. The mean bulk density and mean specific gravity of these categories ranged from 0.488-0.944 g cm-3 and 2.017-2.390 g cm-3, respectively, and both increased as a function of decreasing particle size. Samples of coal ash from four pulverized coal-fired furnaces were obtained, and demonstrated mean "2"2"6Ra concentrations ranging from 6.44-7.59 dpm g-1. The mean bulk density and mean specific gravity of these samples ranged from 1.254-1.520 g cm-3 and 2.357-2.588 g cm-3, respectively. Construction of chambers and methods for measuring "2"2"2Rn emanation coefficients are described. The measured emanation coefficient is shown to be insensitive to ingrowth time at times greater than three days. Measurements of emanation coefficients from ash samples were conducted at moisture contents of 0, 1.0, 10, 20 and 40% moisture by weight, and showed an increase in the emanation coefficient as a function of moisture content up to about 20% moisture by weight. Above 20% moisture content, most samples showed a trend toward decreasing emanation coefficients. The fractionated ash samples showed an increase in the emanation coefficient as a function of decreasing particle size. An experiment was also conducted which confirmed that sample depth was insignificant in explaining the observed emanation coefficient over the range of depths used in the other experiments

1986-01-01

346

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

International Nuclear Information System (INIS)

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

1998-10-01

347

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

348

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

349

Comparability and traceability of coal ash analyses in an interlaboratory study program  

Energy Technology Data Exchange (ETDEWEB)

From results obtained in an interlaboratory study program, performance characteristics for the determination of major and minor elements in coal ash have been established. For several parameters, a functional relationship between the content (grand mean) and the reproducibility and reproducibility standard deviations could be established: Fe{sub 2}O{sub 3},MnO{sub 2},Na{sub 2}O,K{sub 2}O,MgO,CaO, and SO{sub 3} content in ash. In the interlaboratory study program, it was verified that the data between rounds were comparable. This verification was carried out using blind samples. (orig.) With 12 figs., 5 refs.

Veen, A.M.H. van den; Broos, A.J.M. [Nederlands Meetinstituut, Delft (Netherlands)

1998-11-01

350

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

Science.gov (United States)

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(3+) and Fe(2+)/Fe(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(-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(3+) and Fe(3+) and introduced Ca(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. PMID:22197558

Yan, Long; Wang, Yufei; Ma, Hongzhu; Han, Zhiping; Zhang, Qiang; Chen, Yashao

2012-02-15

351

Characterization of coal fly ash components by laser-induced breakdown spectroscopy  

International Nuclear Information System (INIS)

The high sensitivity of laser-induced breakdown spectroscopy (LIBS) for the detection of most of the fly ash components enables the analysis of these residues produced during the combustion of coal. Fly ash consists of oxides (SiO2, Al2O3, Fe2O3, CaO...) and unburnt carbon which is the major determinant of combustion efficiency in coal fired boilers. For example, an excessive amount of residual carbon dispersed in the fly ash means a significant loss of energy (Styszko et al., 2004). Standard methods employed for the analysis of fly ash make not possible a control of boiler in real time. LIBS technique can significantly reduce the time of analysis, in some cases even an online detection can be performed. For this reason, some studies have been addressed in order to demonstrate the capability of the laser-induced breakdown spectroscopy technique for the detection of carbon content in high pressure conditions typical of thermal power plants (Noda et al., 2002) and for the monitoring of unburnt carbon for the boiler control in real time (Kurihara et al., 2003). In particular, the content of unburnt carbon is a valuable indicator for the control of fly ash quality and for the boiler combustion. Depending on this unburnt carbon content, fly ash can be disposed as an industrial waste or as a raw material for the production of concrete in the construction sector. In this study, analyses were performed on specimens of various forms of preparation. Pressed pellets were prepared with two different binders. Presented results concern the nature and amount of the binder used to pelletize the powder, and the laser-induced breakdown spectroscopy parameters and procedure required to draw calibration curves of elements from the fly ash. Analysis 'on tape' was performed in order to establish the experimental conditions for the future 'online analysis'.

2009-10-01

352

Characterization of coal fly ash components by laser-induced breakdown spectroscopy  

Energy Technology Data Exchange (ETDEWEB)

The high sensitivity of laser-induced breakdown spectroscopy (LIBS) for the detection of most of the fly ash components enables the analysis of these residues produced during the combustion of coal. Fly ash consists of oxides (SiO{sub 2}, Al2O{sub 3}, Fe{sub 2}O{sub 3}, CaO...) and unburnt carbon which is the major determinant of combustion efficiency in coal fired boilers. For example, an excessive amount of residual carbon dispersed in the fly ash means a significant loss of energy. Standard methods employed for the analysis of fly ash make not possible a control of boiler in real time. LIBS technique can significantly reduce the time of analysis, in some cases even an online detection can be performed. For this reason, some studies have been addressed in order to demonstrate the capability of the laser-induced breakdown spectroscopy technique for the detection of carbon content in high pressure conditions typical of thermal power plants and for the monitoring Of unburnt carbon for the boiler control in real time. In particular, the content of unburnt carbon is a valuable indicator for the control of fly ash quality and for the boiler combustion. Depending on this unburnt carbon content, fly ash can be disposed as an industrial waste or as a raw material for the production of concrete in the construction sector. In this study, analyses were performed on specimens of various forms of preparation. Pressed pellets were prepared with two different binders. Presented results concern the nature and amount of the binder used to pelletize the powder, and the laser-induced breakdown spectroscopy parameters and procedure required to draw calibration curves of elements from the fly ash. Analysis 'on tape' was performed in order to establish the experimental conditions for the future 'online analysis'.

Ctvrtnickova, T.; Mateo, M.P.; Yanez, A.; Nicolas, G. [University of La Coruna, Ferrol (Spain)

2009-10-15

353

Characterization of coal fly ash components by laser-induced breakdown spectroscopy  

Science.gov (United States)

The high sensitivity of laser-induced breakdown spectroscopy (LIBS) for the detection of most of the fly ash components enables the analysis of these residues produced during the combustion of coal. Fly ash consists of oxides (SiO 2, Al 2O 3, Fe 2O 3, CaO…) and unburnt carbon which is the major determinant of combustion efficiency in coal fired boilers. For example, an excessive amount of residual carbon dispersed in the fly ash means a significant loss of energy (Styszko et al., 2004 [1]). Standard methods employed for the analysis of fly ash make not possible a control of boiler in real time. LIBS technique can significantly reduce the time of analysis, in some cases even an online detection can be performed. For this reason, some studies have been addressed in order to demonstrate the capability of the laser-induced breakdown spectroscopy technique for the detection of carbon content in high pressure conditions typical of thermal power plants (Noda et al., 2002 [2]) and for the monitoring of unburnt carbon for the boiler control in real time (Kurihara et al., 2003 [3]). In particular, the content of unburnt carbon is a valuable indicator for the control of fly ash quality and for the boiler combustion. Depending on this unburnt carbon content, fly ash can be disposed as an industrial waste or as a raw material for the production of concrete in the construction sector. In this study, analyses were performed on specimens of various forms of preparation. Pressed pellets were prepared with two different binders. Presented results concern the nature and amount of the binder used to pelletize the powder, and the laser-induced breakdown spectroscopy parameters and procedure required to draw calibration curves of elements from the fly ash. Analysis "on tape" was performed in order to establish the experimental conditions for the future "online analysis".

Ctvrtnickova, Tereza; Mateo, Mari-Paz; Yañez, Armando; Nicolas, Gines

2009-10-01

354

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1998-03-01

355

Dry deshaling of high ash Indian coal by infrasizers  

Energy Technology Data Exchange (ETDEWEB)

Most coal deposits in India have a high shale content. As a result coal beneficiation is considered to be of utmost importance. Wet deashing causes water pollution, so dry processes were examined. The method studied involves elutriation to effect separation with the help of infrasizers. A pilot plant was set up and experiments carried out to: experimentally review the performance characterisitcs of an infrasizer system; and develop a mathematical model to predict the separation efficiency for multistage operation. The problems of wet deashing were studied at the coal washery of the Dagpur Steel Plant, and the lessons learnt applied to specify the requirements for a dry plant. Experiments were performed to establish the usefulness of an infrasizer for handling very fine coal particles, which tend to jam jigs. A blower was used to handle the particles, and a mathematical model constructed using the data obtained. From this work dry deashing of Indian coal does indeed appear to be feasible. 6 refs., 5 tabs., 2 figs.

Banerjee, S.; Mallick, D.S.; Dey, A. [B.E. College, Howrah (India). Dept. of Mining Engineering

1993-11-01

356

Neo-mineral formation during artificial coalification of low-ash - mineral free-peat material from tropical Malaysia-potential explanation for low ash coals  

Energy Technology Data Exchange (ETDEWEB)

Abundant coal deposits have very low inorganic contents (ash yield; < 2%) and hence are almost ash-free. Inexplicable to date is that the precursor of coal, modern peat deposits, almost nowhere have such low ash yields as a result of both the inorganic mineral and biogenic phytolith contents. However, despite the common occurrence of phytoliths in modern peats, they are invariably absent in coals. It has thus been hypothesized by some investigators that modern environments are not ideal analogues for the formation of low ash coal deposits. Here we present new evidence to suggest that mineral diagenesis during coalification can transform biogenic inorganics to new minerals and that a substantial component of these new minerals could be removed in solution during expulsion of moisture with coalification resulting in low ash precursors of coal. This study presents results from artificial coalification experiments of modern tropical forest peat material with ash yields between 2-4.3 wt.%. The inorganic material of the peat consists almost exclusively of Al-Si-and Si-rich phytoliths and other bioliths; no other inorganic mineral matter is present. Compressed pellets of dried peat were deformed in a Griggs constant strain rate apparatus at a constant confining pressure of 5 kb and constant strain rate of 10{sup -} {sup 5} s {sup -} {sup 1} at variable temperatures from 350 C to 550 C. The samples, exposed to artificial coalification processes, were then analysed by SEM, EDS, and XRD for semi-quantitative chemical analyses. The deformed material showed a lack of any biogenic silica and Al-Si-phytoliths, but contained neoformed idiomorphic quartz crystals and clays. We conclude that modern peat forming environments that have low-ash peats containing biogenic silica and other biogenic Al-Si-material can represent precursors of very low-ash coal deposits. Our experiments illustrate that during coalification, it is likely all or almost all biogenic material is transformed into new minerals, mainly quartz and clay minerals, such as kaolinite. Because natural systems are not confined to the same degree as our experiments, it is likely that part or all of the inorganic fraction migrates in solutions out of the peat or coal seam with available fluids, resulting in an almost ash-free coal deposit. (author)

Wuest, Raphael [School of Earth and Environmental Sciences, James Cook University, Townsville, 4811, QLD (Australia); Bustin, R. Marc; Ross, John [Department of Earth and Ocean Sciences, University of British Columbia, 6339 Stores Road, Vancouver, B.C. (Canada)

2008-04-03

357

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

International Nuclear Information System (INIS)

The ultrafine fraction of particles produced during the combustion of coal are the most difficult to remove with control devices and are retained longest in the atmosphere. Combustion of a high-sulfur coal, such as Illinois No. 6, produces a significant quantity of sulfuric acid, most of which is absorbed to the surface of those particles smaller than 1 ?m in diameter. Particles smaller than 0.05 ?m in diameter, moreover, consist largely of sulfuric acid; since these particles penetrate to the deepest regions of the lung, exposure to coal fly ash can result in the administration of large doses of acid to the alveolar tissues. Using a combustion system that generates coal fly ash similar to that collected in flue gas, guinea pigs were exposed for 2 h to aerosols produced from Illinois No. 6 (mean aerodynamic diameter 0.2 ?m) at concentrations of 5 and 20 mg/m3. The animals were lavaged at 24 h post-exposure and levels of dehydrogenase (LDH), ?-glucuronidase (?-GC), and protein were compared to those of control animals. After 24 h, no changes in levels of LDH and ?-GC were seen in the lavage fluid from both high-dose and low-dose animals. Slight, but statistically significant elevations in protein concentration were measured in the high-dose exposure group. The total cell number in the lavage fluid was also found exposure group. The total cell number in the lavage fluid was also found to be exchanged following both exposures. 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

1991-03-01

358

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

359

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

Directory of Open Access Journals (Sweden)

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

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

Goñi, S.

2010-06-01

360

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

International Nuclear Information System (INIS)

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

1983-01-01

 
 
 
 
361

Trace element concentrations and the growth of various types of crop in sandy soil with coal ash admixture  

Energy Technology Data Exchange (ETDEWEB)

Cultivation tests of six types of crop were carried out in a growing medium consisting of washed sandy soil into which three kinds of coal ash had been mixed. The aim of the tests was a basic investigation of the adsorption and accumulation by crops of trace elements derived from coal ash. 1) The growth of kidney beans and soya beans was markedly inhibited by the presence of coal ash. Although the growth of cabbages and of the above-ground parts of Japanese radishes was hardly affected, growth of the radish roots was retarded. 2) Investigations were made of the concentrations of ten elements in the crops grown. It was discovered that the concentrations of As, B, Mo, Se and Sr tended to rise when coal ash had been added, but that the Mn concentration dropped. The trends seen in the concentration of Fe, Sb and Zn varied from one crop to another. (14 refs.) (In Japanese)

Kawano, Y.; Takanashi, N.; Fujimoto, T.

1982-01-01

362

Fly ash formation and penetration through the electrostatic precipitator at PC boilers firing South African and Colombian coals  

Energy Technology Data Exchange (ETDEWEB)

We have studied in detail the properties of fly ash particles in the size range 0.01 to 100 um formed during the combustion of South African and Colombian coals as well as the fly ash penetration through the electrostatic precipitators (ESP). Both coals were fired at a modern, pulverized coal fired boiler. In addition, South African coal was fired at another boiler. Both boilers were equipped with ABB ESP`s. In addition to standard coal analyses methods, both coals were analyzed with computer controlled scanning electron microscopy (CCSEM) to find more detailed information on the distribution of ash forming constituents in coal. Fly ash number and mass size distributions upstream and downstream the ESP were measured with the differential mobility analyzers and low pressure impactors, respectively. Fly ash upstream and downstream the ESPs was analyzed with CCSEM. Fly ash microstructure was determined with SEM and TEM. Fly ash particle number size distributions at conditions upstream the ESP showed a broad mode at 0.1 to 0.2 um. Electron micrographs showed that these ultrafine particles were chain-like agglomerates having few to several tens of 20 to 50 nm primary particles within each agglomerates Primary particles were mostly amorphous oxides of Al and Si coated with Ca. Particles larger than 0.1 um were spheres having ultrafine Primary particles and agglomerates deposited on the surface. Mass size distributions showed a major mode at 15 um. Only 1 to 2 percent of fly ash was smaller than 0.5 um on the mass basis, i.e. had vaporized during combustion. ESP penetration curves showed clear maxima at 0.1 to 1 um. CCSEM results indicated that supermicron fly ash penetration through the ESP was a function of both particle size and composition.

Kauppinen, E.I.; Lind, T.M.; Ylatalo, V. [VTT Chemical Technology, Espoo (Finland)] [and others

1995-12-31

363

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

International Nuclear Information System (INIS)

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

1983-11-01

364

EVALUATION OF THE EFFECTS OF COAL FLY ASH AMENDMENTS ON THE TOXICITY OF A CONTAMINATED MARINE SEDIMENT  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Approaches for cleaning-up contaminated sediments range from dredging to in situ treatment. In the present report, 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 ash...

Burgess, Robert M.; Perron, Monique M.; Friedman, Carey L.; Suuberg, Eric M.; Pennell, Kelly G.; Cantwell, Mark G.; Pelletier, Marguerite C.; Ho, Kay T.; Serbst, Jonathan R.; Ryba, Stephan A.

2009-01-01

365

Variations of mercury content in feed coal and fly ash from a coal-fired power plant over thirty-eight weeks; parameters influencing the variation  

Energy Technology Data Exchange (ETDEWEB)

Subbituminous feed coals and its corresponding fly ashes were sampled and analyzed from a coal-fired power plant from Alberta, Canada over a period of thirty-eight weeks. The feed coals were analyzed for proximate analysis, Hg, sulphur, and ash content. The fly ashes were examined for C and Hg content. The carbon/char and carbon content of fly ashes were separated using an HCl and HF digestion. The carbon/char in the fly ash was grouped into reactive vitrinitic/bimacerate and less reactive inertinitic chars. The results indicates that the highly porous vitrinitic/bimacerate chars may be responsible for the capture of mercury, as suggested by the positive correlation between mercury and carbon content of fly ash and with vitrinitic/bimacerate chars. The emitted mercury was calculated and compared to mercury emitted from the stack during the mass balance study. The mercury content of feed coal ranged from 0.029 to 0.069 mg/kg. The present results also shows some variation in the amount of mercury captured by fly ash, ranging from 0.069 to 0.112 mg/kg, or from 24 to 51%, mercury input by feed coal. 23 refs., 7 figs.

F. Goodarzi; J. Reyes; D. Rose [Geological Survey of Canada-Calgary, Calgary, AB (Canada). Environmental Studies Group

2005-07-01

366

Synthesis of zeolite from Italian coal fly ash: Differences in crystallizationtemperature using seawater instead of distilled water  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this study Italian coal fly ash was converted into several types of zeolite in laboratory experiments with temperatures of crystallization ranging from 35 up to 90 °C. Distilled and seawater were used during the hydrothermal synthesis process in separate experiments, after a pre-treatment fusion with NaOH. The results indicate that zeolites could be formed from different kind of Italian coal fly ash at low temperature of crystallization using both distilled and seawater. SEM data an...

Belviso, C.; Fiore, S.; Cavalcante, F.

2010-01-01

367

Distribution of polycyclic aromatic hydrocarbons in fly ash during coal and residual char combustion in a pressurized fluidized bed  

Energy Technology Data Exchange (ETDEWEB)

To investigate the distribution of polycyclic aromatic hydrocarbons (PAHs) in fly ash, the combustion of coal and residual char was performed in a pressurized spouted fluidized bed. After Soxhlet extraction and Kuderna-Danish (K-D) concentration, the contents of 16 PAHs recommended by the United States Environmental Protection Agency (U.S. EPA) in coal, residual char, and fly ash were analyzed by a high-performance liquid chromatography (HPLC) coupled with fluorescence and diode array detection. The experimental results show that the combustion efficiency is lower and the carbon content in fly ash is higher during coal pressurized combustion, compared to the residual char pressurized combustion at the pressure of 0.3 MPa. Under the same pressure, the PAH amounts in fly ash produced from residual char combustion are lower than that in fly ash produced from coal combustion. The total PAHs in fly ash produced from coal and residual char combustion are dominated by three- and four-ring PAHs. The amounts of PAHs in fly ash produced from residual char combustion increase and then decrease with the increase of pressure in a fluidized bed. 21 refs., 1 fig., 4 tabs.

Hongcang Zhou; Baosheng Jin; Rui Xiao; Zhaoping Zhong; Yaji Huang [Nanjing University of Information Science and Technology, Nanjing (China)

2009-04-15

368

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 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

1999-10-11

369

Simultaneous Reduction of SOx and Fine Ash Particles During Combustion of Coals Added with Additives  

Science.gov (United States)

SO2 emission from coal combustion is the important problem in many countries. This paper aims to evaluate the possibility of simultaneous reduction of SOx and fine ash particles during combustion of coal added with inorganic Ca-containing sorbent and organic Mg-containing sorbent in the fluidized bed conditions. Compared to addition of limestone particles to coal, the use of these sorbents produces the ultra-fine active oxides in the coal/char at higher temperature. The formed ultra-fine active oxides provide larger reaction surface area for the S and chemical sorbents, and, therefore, the high desulfurization efficiency will be expected in the fluidized bed coal combustion. In addition, the addition of chemical additives can affect the mineral transformation process during combustion. The results indicate that at certain temperature, higher sulfur removal efficiency can be obtained for selected Ca- and Mg-rich sorbents than those of natural limestone under fluidized bed combustion conditions. It is mainly due to the fine dispersion of Ca and Mg in impregnated coal so that a good is obtained between calcium and sulfur-containing coal particles. The addition of additives has a visible impact on the particle size distribution and chemical composition of the PM, wherein, it improves the degree of coalescence of sub-micron and fine mineral particles, which reduces PM2.5 emissions. For the selected coal, the effect on the reduction of PM2.5 emissions strongly depends on the addition and the type of sorbent being used.

Nlnomiya, Yoshihiko; Xu, Shuyin; Wang, Qunying; Cheng, Yi; Awaya, Isao

370

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

371

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

Science.gov (United States)

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. PMID:18063375

Mahur, A K; Kumar, Rajesh; Mishra, Meena; Sengupta, D; Prasad, Rajendra

2008-03-01

372

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

Energy Technology Data Exchange (ETDEWEB)

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 U-238, Th-232, and K-40 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.

Mahur, A.K.; Kumar, R.; Mishra, M.; Sengupta, D.; Prasad, R. [Aligarh Muslim University, Aligarh (India)

2008-03-15