Environmental Engineering Commons^™

Fouling Intensity Of Three Indian Coals, S. Balakrishnan, R. Nagarajan

Coal Combustion and Gasification Products Journal Archive

Ash particles can arrive at heat-transfer surfaces either in solid (solidified) state or in molten state, depending on the factors such as location inside the boiler, temperature, and residence time. In this study, arrival of ash particles in solid state, which can occur in the convective section of the boiler, was considered. Apart from the inertial force that drives particles .10 mmto the surface, the low-melting inorganic alkali vapors play a vital role in deposit formation by promoting sticking. Chemical equilibrium calculations were performed to calculate the equilibrium composition of flue gas, as well as the amount of condensable inorganic …

Chemical Weathering And Mobility Of Inorganic Species In Dry Disposed Ash: An Insight From Geochemical Fractionation And Physicochemical Analysis, S.A. Akinyemi, W.M. Gitari, A. Akinlua, L.F. Petrik

Coal Combustion and Gasification Products Journal Archive

The burning of low-grade coal produces vast amounts of ash and other solid by-products. In South Africa, coal combustion by-products undergo disposal on land as dry heaps or slurried to dams. In this study, the geochemical partitioning, transport, and mobility of elements in dry disposed ash dumps were investigated using a modified sequential extraction scheme. The chemical and mineralogical compositions of 50 drilled core samples were investigated by X-ray fluorescence (XRF), X-ray diffraction (XRD), and inductively coupled plasma mass spectrometry. Ternary plots of major elements as determined by XRF showed that the 15-year-old and 2-week-old dry disposed ashes are sialic, …

Biological Control Of Manganese In Water Supplies In The Presence Of Humic Acids, Michael S. Snyder

Theses and Dissertations--Civil Engineering

The main objective of this study was to improve our understanding of biological filtration (biofilm type) treatment for manganese (Mn) removal in drinking water. Biological filtration treatment involves biofilms of Mn(II)-oxidizing microorganisms attached to solid filter material that remove and immobilize dissolved Mn(II) in raw water by conversion to black MnO_2(s) precipitates. Mn-biological filtration is an emerging green technology that can serve as an alternative to conventional physicochemical treatments but its full potential is hindered by various factors. These include lack of understanding the: (1) optimal removal conditions for Mn, (2) mechanisms for Mn releases of the accumulated Mn …

Hydrologic Characterization Of A Rain Garden Mitigating Stormwater Runoff From A Commercial Area, John T. Mcmaine

Theses and Dissertations--Biosystems and Agricultural Engineering

Impervious surfaces such as roads, sidewalks, and roofs increase the volume of runoff generated in a watershed. Traditional stormwater management techniques emphasize conveyance of runoff away from impervious surfaces in order to reduce flooding. Rain gardens are becoming popular as a different means to manage stormwater in such a way that runoff is captured and infiltrated onsite rather than conveyed offsite. A stormwater management system consisting of a rainwater harvest system, rain garden, and infiltration chamber was built at the Coca-Cola Refreshments USA, Inc. distribution center in Lexington, Kentucky during the fall of 2011. Precipitation, inflow, and water level were …

Froth Flotation Performance Enhancement By Feed Cavitation And Magnetic Plastic Particle Addition, Mehmet Saracoglu

Theses and Dissertations--Mining Engineering

Froth flotation is the most commonly used process to recover and upgrade the portion of the coal preparation plant feed that has a particle size smaller than 150 microns. Problems that occur when employing froth flotation in the coal industry include i) coal surfaces that are weakly-to-moderately hydrophobic, and ii) flotation systems that are overloaded and limited by insufficient retention time.

Research was performed to evaluate techniques that could be implemented to improve flotation performance under the aforementioned scenarios. Pre-aeration of flotation feed using a cavitation system was extensively evaluated in laboratory and full-scale test programs. The benefits of adding …

Using Gis To Delineate Headwater Stream Origins In The Appalachian Coal-Belt Region Of Kentucky, Jonathan A. Villines

Theses and Dissertations--Biosystems and Agricultural Engineering

Human activity such as surface mining can have substantial impacts on the natural environment. Performing a Cumulative Hydrologic Impact Assessment (CHIA) of such impacts on surface water systems requires knowing the location and extent of these impacted streams. The Jurisdictional Determination (JD) of a stream’s protected status under the Clean Water Act (CWA) involves locating and classifying streams according to their flow regime: ephemeral, intermittent, or perennial. Due to their often remote locations and small size, taking a field inventory of headwater streams for surface mining permit applications or permit reviews is challenging. A means of estimating headwater stream location …

Concentration Effects And Ion Properties Controlling The Fractionation Of Halides During Aerosol Formation, Marcelo I. Guzman, Richa R. Athalye, Jose M. Rodriguez

Chemistry Faculty Publications

During the aerosolization process at the sea surface, halides are incorporated into aerosol droplets, where they may play an important role in tropospheric ozone chemistry. Although this process may significantly contribute to the formation of reactive gas phase molecular halogens, little is known about the environmental factors that control how halides selectively accumulate at the air-water interface. In this study, the production of sea spray aerosol is simulated using electrospray ionization (ESI) of 100 nM equimolar solutions of NaCl, NaBr, NaI, NaNO(2), NaNO(3), NaClO(4), and NaIO(4). The microdroplets generated are analyzed by mass spectrometry to study the comparative enrichment of …

Microstructural And Mineralogical Transformation Of Hydraulically Disposed Fly Ash—Implications To The Environment, Jabulani S. Mahlaba, Elsabe P. Kearsley, Richard A. Kruger

Coal Combustion and Gasification Products Journal Archive

Increasing amounts of coal are combusted annually to meet the ever-increasing energy demands. The inevitable by-products include fly ash and saline effluents, which require acceptable disposal. The aim of this article is to compare the effect of hydraulic disposal with dry ash dumping. The results indicate that the former carries more environmental benefits based on the physical, chemical, and mineralogical aspects that were investigated.

Cordyline Fruticosa Growth And Soil Microbial Quality With Topical Application Of Coal Combustion By-Products Aggregates, Sangchul Hwang, Isomar Latorre, Eileen Irizarry

Coal Combustion and Gasification Products Journal Archive

Coal combustion by-products aggregates (CCAs) are a solidified composite of fly and bottom ashes (2:1, by wt). Here, we assessed the feasibility of beneficial use of CCAs as a soil amendment or conditioner by conducting an outdoor experiment with Cordyline fruticosa (lucky plant) to determine its growth and soil microbial quality under the influence of topical CCA application (95 tons ha21). Enhanced growth of C. fruticosa with CCA application was noted, with respect to plant height, growth rate, leaf size, and leaf chlorophyll intensity. Soil dehydrogenase activity and total heterotrophic bacteria count were greater with topical CCA application, especially in …

Influence Of Activator Solution Formulation On Fresh And Hardened Properties Of Low-Calcium Fly Ash Geopolymer Concrete, Carlos Montes, Erez N. Allouche

Coal Combustion and Gasification Products Journal Archive

The effect of the composition of activator solutions on fresh and hardened properties of geopolymer concrete was investigated. Research variables included liquid sodium silicate product (DH, NH, and StarH), sodium hydroxide molar concentration (6, 10, and 14), and sodium silicate–to–sodium hydroxide ratio (1, 2, and 3). Response variables were compressive strength, corrosion resistance expressed as remaining compressive strength and mass loss, and flowability. Results were analyzed using Minitab statistical software. Findings suggest that activator solution formulation has a significant effect on the properties of the resulting geopolymer binder. The experimental design used was found effective in establishing the optimum activator …

Mineralogical Transformations In Coal Feedstocks During Carbon Conversion, Based On Packed-Bed Combustor Tests: Part 2. Behavior Of Individual Particles, Ratale H. Matjie, Colin R. Ward, Zhongsheng Li

Coal Combustion and Gasification Products Journal Archive

Handpicked carbon-rich particles (coal or char), mineral-rich particles (heated stones), and bonded stone aggregates (clinkers) from the upper and lower parts of a pilot-scale packed-bed combustor bed, designed to simulate conversion or combustion processes, were subjected to mineralogical and inorganic geochemical studies, in order to evaluate the reactions that may occur during carbon conversion at a particle-by-particle scale. The mineral matter of the carbon-rich particles was found to have higher proportions of carbonate minerals and kaolinite than the mineral-rich (stone) particles in the coal feedstocks used in the study, and to form phases such as anorthite, gehlenite, pyrrhotite, troilite, and …

Mineralogical Transformations In Coal Feedstocks During Carbon Conversion, Based On Packed-Bed Combustor Tests: Part 1. Bulk Coal And Ash Studies, Ratale H. Matjie, Colin R. Ward, Zhongsheng Li

Coal Combustion and Gasification Products Journal Archive

Mineralogical and inorganic geochemical studies have been carried out on composite samples of six different coarse-crushed (,120 mm) feed coals tested in a pilot-scale packed-bed combustor designed to simulate conversion and some fixed-bed combustion processes, and also on composite samples of the ashes produced. The mineral matter of the coals consisted mainly of quartz, kaolinite, and Ca-bearing carbonate minerals (calcite, dolomite, aragonite), with minor proportions of illite, pyrite, and several other phases, along with some Ca in an organically associated form. The base to acid ratio of the coal ashes ranged from 0.1 to 0.3, due mainly to variations in …

Potential Indoor Air Exposures And Health Risks From Mercury Off-Gassing Of Coal Combustion Products Used In Building Materials, Christopher M. Long, Sonja N. Sax, Ari S. Lewis

Coal Combustion and Gasification Products Journal Archive

Coal combustion products (CCPs), including coal fly ash (CFA) and flue gas desulfurization (FGD) gypsum, have gained accepted use as substitutes for traditional substances in building materials. Because of the presence of mercury (Hg) in CCP materials, some concerns have been raised regarding the potential for Hg to off-gas from building materials into indoor air. Risk assessment offers a well-accepted, objective framework in which to determine whether such off-gassing could result in humanexposures of health concern. We thus conducted a screening-level human health risk assessment to estimate worst-case inhalation risks from indoor air exposures to Hg for multiple CCP utilization …

Quantifying The Benefits Of Using Flue Gas Desulfurization Gypsum In Sustainable Wallboard Production, Jin Cheol Lee, Sabrina L. Bradshaw, Tuncer B. Edil, Craig H. Benson

Coal Combustion and Gasification Products Journal Archive

Electric utilities produce more than 11.2 Mt of flue gas desulfurization (FGD) gypsum annually. Approximately 7.5 Mt is used in wallboard production. This article examines the environmental and cost benefits associated with replacement of natural gypsum in wallboard with FGD gypsum. A life-cycle analysis program was used to quantify the benefits of using FGD gypsum from electric power production in wallboard construction. Comparisons were made between energy consumption, water use, and greenhouse gas (GHG) emissions associated with obtaining and processing virgin gypsum material and those with FGD gypsum. The added impact of disposing of the unused FGD gypsum in landfills …

Waste Classification Of Slag Generated In A Pilot-Scale Entrained-Flow Gasifier, Ashleigh Cousins, Robin W. Hughes, David J. Mccalden, Dennis Y. Lu, Edward J. Anthony

Coal Combustion and Gasification Products Journal Archive

Series of gasification tests have been completed in the pilot-scale entrained-flow slagging gasifier at CanmetENERGY using Canadian coals, oil-sand coke, and blends of these fuels to determine if the produced slags are nonhazardous in nature. Solid wastes generated during these tests were analyzed for their trace metals, crystallinity, and toxic constituent leaching tendency in an attempt to provide more insight into the possibility of disposal or by-product use of gasifier-produced solid waste. The gasification tests were performed at conditions representative of commercial gasifiers using a dry-fuel-feed configuration. The lower-volatility elements were found to partition between the slag and process-water solids …

Identifying Hot-Spots Of Fecal Contamination In The Royal Spring Karstshed, Samuel C. Lee

Theses and Dissertations--Civil Engineering

The City of Georgetown, Kentucky relies on a vast karst spring network as a drinking water source. This karst feature has several inputs from sinkholes and streams in the Cane Run Watershed: a watershed associated with a variety of land uses in the recharge area. The recharge area encompasses the area from North Lexington to Georgetown and is composed of urban, suburban, agricultural and industrial usage. A serious water quality issue exists with respect to the impact of fecal contamination within the spring recharge area. Identification of fecal contamination is quantified by microbial indicators adapted from surface water applications: fecal …

Development Of Strategies To Minimize The Release Of Trace Elements From Coal Waste Sources, Mohammad Rezaee

Theses and Dissertations--Mining Engineering

To assess strategies aimed at minimizing the release of trace elements and the impact of disposal of coal waste materials on the environment, two long-term leaching experiments of up to five months duration were performed using waste materials from two plants cleaning high and low sulfur bituminous coal. The tests evaluated the mobility of major trace elements under different disposal scenarios: (i) a static leaching test designed to simulate the quiescent conditions encountered by coal waste material stored under water in a stable impoundment, and (ii) a dynamic test to simulate waste materials exposed to the atmosphere, either in variable …

Effect Of Additive On The Performance Characteristics Of Centrifugal And Progressive Cavity Slurry Pumps With High Concentration Fly Ash Slurries, Sunil Chandel, S.N. Singh, V. Seshadri

Coal Combustion and Gasification Products Journal Archive

Slurry pumps that are used in the hydraulic transportation of fly ash slurries through pipes in thermal power plants can be broadly classified into two main categories namely positive displacement and centrifugal pumps. The two types of pumps differ considerably in construction as well as in operating principle compared to the conventional pumps. The present study reports the effect of additive on the performance characteristics of centrifugal and progressive cavity screw pumps with fly ash slurries at high concentrations (above Cw < 50% by weight). Mixture of sodium carbonate and Henko detergent (5:1) at a concentration of 0.2% by weight has been used as an additive. For each type of pump, the effect of additive on the performance characteristics has been experimentally evaluated at rated speed with fly ash slurries in the concentration range of 50 to 70% by weight. The pump total head, overall efficiency and pump input power as a function of flow rate have been measured. The results obtained from the centrifugal slurry pump performance show that at rated speed, the performance of the pump improves with the addition of drag reducing additive. In the case of progressive cavity screw pump, pump performance characteristics and behavior were completely different as compared to the centrifugal slurry pump. At rated speed, the performance of screw pump deteriorates with the addition of drag reducing soap solution.

Zinc Speciation In Power Plant Burning Mixtures Of Coal And Tires, Luis F.O. Silva, Marcos L.S. Oliveira, Carmen Serra, James C. Hower

Coal Combustion and Gasification Products Journal Archive

Fly ash from the cyclone-boiler co-combustion of high-S, high volatile bituminous coal and tire-derived fuel (tdf) was studied using a variety of chemical, optical, and microbeam techniques. Fly ash, dominated by Al-Si glass with lesser amounts of coalderived carbons, Fe-spinels, and tire-derived carbons, has Zn concentrations ranging from 2200 ppm (1st ESP row) to 6900 ppm Zn (3rd ESP row). Zinc occurs in Zn-rich nanoparticles in the Al-Si glass phases and as ZnO in amorphous and crystalline nanominerals, Fe- and Zn-sulfides, Pb-Al-Fe sulfates, and Zn sulfates. Iron-rich, Al- and Ti-bearing spinels contain accessory Zn2+,Cr3+,Mn2+, and Pb2+. Fe-sulfates and phosphates nanoparticles …

Co-Disposal Of Dry Fgd By-Product With Coal Gasification Ash And Inorganic Brines, Jabulani S. Mahlaba, P.C. Pretorius, Subal Maharajh, M.P. Augustyn

Coal Combustion and Gasification Products Journal Archive

There is a growing pressure from the environmental authorities and public bodies to reduce anthropogenic pollution. Stringent environmental legislation is being implemented for industries around the world, even more so for coal consuming industries. Control of gaseous emissions is one of the areas that are receiving considerable attention towards sustainable development. Coal combustion in coal-fired power utilities emits SO~x~ to the atmosphere. Dry flue gas desulphurisation (FGD) is a well known technology often used to mitigate sulphur emissions in coal-fired power utilities. It traditionally uses lime to neutralise SO~x~, and forms a mixture of anhydrite (CaSO~4~), and calcium sulphite (CaSO~3~). …

A Multi-Analytical Approach To Understand The Chemistry Of Fe-Minerals In Feed Coals And Ashes, Marcos L.S. Oliveira, Frans Waanders, Luis F.O. Silva, Andre Jasper, Carlos H. Sampaio, Dursman Mchabe, Rachel S. Hatch, James C. Hower

Coal Combustion and Gasification Products Journal Archive

Seven feed coals used in the Brazilian power generation industry were obtained and subsequently analysed together with fly ash and bottom ash from a major Brazilian power plant. The samples were investigated by means of room temperature FeMo¨ssbauer analyses, X-ray diffraction, Raman spectroscopy, scanning electron microscope and petrographic analysis. In addition, nanometer-sized crystalline phases in coals and ashes were characterised using an energy-dispersive X-ray spectrometer and a high-resolution transmission electron microscope. The major identified Fe-bearing minerals in the coals were found to be actinolite, ankerite, chalcopyrite, chlorite, goethite, illite, ilmenite, magnesioferrite, natrojarosite, pyrite, pyrrhotite, and siderite; whilst in the fly …

Compositional Variations In Pilot Gasifier And Laboratory-Produced Slags And Their Impacts On Slag Viscosity And Coal Assessment, Alexander Ilyushechkin, Daniel Roberts, David Harris

Coal Combustion and Gasification Products Journal Archive

The flow behaviour of coal mineral matter at high temperatures is an important parameter for coal use in entrained-flow gasification technologies. Recently, gasification performance data was obtained from a series of pilot-scale gasification tests on a suite of well-characterised Australian black coals. Evaluation of the results of the pilot tests and the detailed laboratory investigations provided the opportunity for evaluation of the practical applicability of different laboratory and modelling techniques for coal assessment in terms of mineral matter behaviour in entrained flow gasification. A series of viscosity measurements was made over the range 1200–1600uC using slags produced in a pilot …

Compaction Of High-Ca Fly Ash-Al- And Al-Alloy-Composites: Evaluation Of Their Microstructure And Tribological Performance, Grigorios Itskos, Angeliki Moutsatsou, Pradeep K. Rohatgi, Nikolaos Koukouzas, Charalampos Vasilatos, Eleni Katsika

Coal Combustion and Gasification Products Journal Archive

In this study, highly calcareous and siliceous fly ash particles were utilized for the fabrication of Al- and Al-alloy-based MetalMatrix Composites (MMCs) by means of powder metallurgy. After compacting and sintering Al and Al/Si powders containing 10, 15, and 20wt. % ash particles, the homogenous (and with minimal amount of voids) microstructure of the produced composites was verified by means of Scanning Electron Microscopy (SEM). The composites were tested for their dry sliding wear behavior using a pin-on-disc machine against spheres of alumina. The worn surfaces of composites were then examined by using SEM and Energy Dispersive X-Ray Spectroscopy (EDS). …

Influence Of Chemical Reagents On Rheological Properties Of Fly Ash-Water Slurry At Varying Temperature Environment, H.K. Nail, M.K. Mishra, Karanam U.M. Rao

Coal Combustion and Gasification Products Journal Archive

About 70% of total electrical energy is generated from thermal power plants in India which in turn release about 160 Mt of fly ash as solid waste annually. Transportation and disposal of such a huge amount of fly ash is a major problem faced by the power plants. Presently fly ash is transported as lean slurry in pipe lines requiring about 80 to 85% of water with high energy input. A major impediment in high volume transportation of fly ash is its high specific gravity as compared to that of water. The objective of the present study was to evaluate …

Impact Of Manufactured Coal Ash Aggregates On Water Quality During Open Pit Restoration: 1. A Statistical Screening Test, Sangchul Hwang, Isomar Latorre

Coal Combustion and Gasification Products Journal Archive

Utilization of manufactured coal ash aggregates (MAs) as a subsoil substitute during restoration of an open pit was assessed in a three-factor, two-level factorial analysis. The factors of interest were the MA application rate (2:1 or 1:2 topsoil/MA volume ratio), rainfall intensity (high or low), and aggregate size (2.36–4.75 mm or 4.75–9.53 mm). Among the water quality parameters examined (pH, turbidity, heavy metal content (lead and cadmium), conductivity, and hardness), the last two parameters were significantly higher (p,0.05) in soil amended with MAs than in a control reactor using sand. A low rainfall intensity and larger aggregate size resulted in …

The Leachability Of Major Elements At Different Stages Of Weathering In Dry Disposed Coal Fly Ash, S.A. Akinyemi, A. Akinlua, W.M. Gitari, R.O. Akinyeye, L.F. Petrik

Coal Combustion and Gasification Products Journal Archive

Large quantities of solid residue are generated by coal-fired power stations in many parts of the World. The disposal and management of the unused fly ash remains a major problem to the environment. The weathered dry disposed ash cores comprise of major element constituents such as Al, Si, Ca, Mg, Fe, Mn, Na+ and K+. The mobility patterns and mineralogical associations of major elements in weathered dry disposed ash dumps aged 1-year-old, 8-year-old and 20-year-old from a coalfired power station in South Africa were investigated using a modified sequential extraction scheme. The extraction sequence was as follows: (1) water soluble, …

Testing Of Interactions Between Coal Ash Leachates And Rock Materials For Mine Backfill Evaluations, Colin R. Ward, David French, Leanne Stephenson, Ken Riley, Zhongsheng Li

Coal Combustion and Gasification Products Journal Archive

A series of laboratory-based leaching tests has been developed to evaluate the chemical interaction between ash, water and different mine-site rock materials, as a basis for assessing the potential environmental impact of using coal ash as backfill in coal mines. Two different test protocols were used: a two-stage serial batch testing program in which leachate from representative ash samples were allowed to interact separately with relevant rock materials under laboratory conditions, and a single-stage mixed batch testing program in which 50:50 mixtures of the same ashes and rock samples were extracted with water following a similar procedure to leaching tests …

Chemistry Of Coal And Coal Combustion Products From Kentucky Power Plants: Results From The 2007 Sampling, With Emphasis On Selenium, James C. Hower, Thomas L. Robl, Gerald A. Thomas, Shelley D. Hopps, Margaret Grider

Coal Combustion and Gasification Products Journal Archive

Kentucky produced over 8 Mt of coal combustion products (CCPs) in 2006, with 30% of the CCPs being utilized, a significant increase from our 1996 and 2001 surveys. As much of the increase is related to increased utilization of flue-gas desulfurization (FGD) gypsum, the increased production of FGD gypsum coincident with the commissioning of new FGD units and the saturation of the (currently) weak market for new construction, the percentage of utilization may decrease by the time of the next planned survey (2011). The concentration of volatile trace elements in the feed coal and in the pulverizer reject, while associated …

An Investigation Of The Behavior Of Raw Calcareous Fly Ash In Mortar Mixtures, Ioanna Papayianni, Eleftherios K. Anastasiou

Coal Combustion and Gasification Products Journal Archive

The behavior of unprocessed calcareous fly ash in cement mortar mixtures is often questionable and unpredictable and that is one of the difficulties in confining these fly ashes within the limits of standards. This work aims at correlating the material characteristics with its behavior in mortar mixtures. An effort is made to understand how three of the reactive constituents; lime (CaO), silica (SiO2), and sulfates (SO3), affect strength and volume stability. Two raw calcareous fly ashes of different composition emanating from the Ptolemaida area, Greece, were systematically tested to define their profile as cementitious agents that could be incorporated in …

Coal Fired Power Station Ash Products And Eu Regulation, Lindon K.A. Sear

Coal Combustion and Gasification Products Journal Archive

The UK has a long history of the use of coal fired power station ash products in a range of applications in construction. These range from use in concrete as a cementitious material through to its use as a fill material in embankments. While there have been no environmental problems associated with these uses, environmental regulations emanating from the European Union (EU) are increasingly impacting on the use of these materials. Unfortunately it is not a single set of regulations that are being applied, but three separate and apparently disconnected initiatives; these are Registration, Evaluation and Authorisation of Chemicals (REACH), …