Coal Combustion Products Research Articles

The annual meeting of Coal Ash Asia (2015) in Shuozhou, Shanxi Province, China

The annual meeting of Coal Ash Asia was held in Shuozhou, Shanxi Province, China, from September 21st to 24th, 2015 (CAA 2015). More than 700 attendees of 300 organizations from 15 different countries attended the 4 days’ conference, exhibition and seminars. The CAA 2015 focused on the comprehensive utilization technology of powder coal ash and desulfurized gypsum, with the aim to bring researchers, managers, and industry leaders together to share knowledge and develop highest value solutions for managing and utilizing coal combustion products. High-aluminum coal, which is abundant in Shanxi and Inner Mongolia, not only contains unusually high level of Al but also has high concentrations of Li, Ga, and REY (Sun et al., 2016). These elements with high concentrations in high-Al coal are very valuable source to various industries, and therefor make perfect economic sense and add extra benefits into coal mines and power plants if they can be recovered by beneficiation processes (Sun et al., 2012). The research team from Hebei University of Engineering has taken part in the CAA 2015. They gave series of oral presentations related to the integrated extraction of lithium (carbonate) with aluminum, silicon, and possibly gallium, which represents a feasible way for the high value-added The annual meeting of Coal Ash Asia (2015) in Shuozhou, Shanxi Province, China

A systematic analysis of PM2.5 in Beijing and its sources from 2000 to 2012

Particulate matter with an aerodynamic diameter of 2.5 μm or less (PM2.5) is the main air pollutant in Beijing. To have a comprehensive understanding of concentrations, compositions and sources of PM2.5 in Beijing, recent studies reporting ground-based observations and source apportionment results dated from 2000 to 2012 in this typical large city of China are reviewed. Statistical methods were also used to better enable data comparison. During the last decade, annual average concentrations of PM2.5 have decreased and seasonal mean concentrations declined through autumn and winter. Generally, winter is the most polluted season and summer is the least polluted one. Seasonal variance of PM2.5 levels decreased. For diurnal variance, PM2.5 generally increases at night and decreases during the day. On average, organic matters, sulfate, nitrate and ammonium are the major compositions of PM2.5 in Beijing. Fractions of organic matters increased from 2000 to 2004, and decreased afterwards. Fractions of sulfate, nitrate and ammonium decreased in winter and remained largely unchanged in summer. Concentrations of organic carbon and elemental carbon were always higher in winter than in summer and they barely changed during the last decade. Concentrations of sulfate, nitrate and ammonium exhibited significant increasing trend in summer but in reverse in winter. On average they were higher in winter than in summer before 2005, and took a reverse after 2005. Receptor model results show that vehicle, dust, industry, biomass burning, coal combustion and secondary products were major sources and they all increased except coal combustions and secondary products. The growth was decided both changing social and economic activities in Beijing, and most likely growing emissions in neighboring Hebei province. Explicit descriptions of the spatial variations of PM2.5 concentration, better methods to estimate secondary products and ensemble source apportionments models to reduce uncertainties would remain being open questions for future studies.

Effect of Coal Combustion Products on high temperature performance of asphalt mastics

For many years fly ash has been effectively used as a partial replacement of portland cement in the production of different types of concrete, as well as in embankments and soil stabilization. On the other hand, the use of Coal Combustion Products (CCPs) in asphalt pavements has been very limited. Few researchers investigated the application of CCPs in asphalt.This research reports on the effect of CCPs on the high temperature performance of asphalt binders. In this paper 15 CCPs were identified, characterized and investigated for their compatibility with different types of asphalt cement and compared to control mineral filler. Furthermore, the study explored the effect of dosage, physical properties and chemical composition of CCP on the stiffness, phase angle and rutting behavior of mastics.The investigation of the rheological performance of asphalt binders with different types of CCPs using Dynamic Shear Rheometer (DSR) confirmed the feasibility of using these by-products to improve the permanent deformation resistance of asphalt binders. Research data demonstrate that the effect of the CCPs is dependent on the dosage and physical and chemical properties of CCP. Based on the rheological response of CCP based mastics at high temperatures this study found a strong physical and chemical interaction between the CCP and the asphalt binder.

Use of fly ash in production of light-weight building bricks

Fly ash is one of the coal combustion products (CCPs) of coal burning power plants and it contains substantial amounts of potentially harmful constituents to the environment. It is known that nearly 600 million tons of fly ash is produced in the world per-annum. In Turkey, the annual production of fly ash is, on average, 13 million tons and only a small amount of this is utilized. This study examines the production of light-weight, high thermal insulating bricks made out of the fly ash and lime. Cylindrical brick samples were produced through steam curing of Seyitömer thermal power plant fly ash and lime mixtures in an autoclave in order to determine the optimum conditions for mechanically sound bricks. Subsequently, at the optimum conditions determined, real-size bricks were produced and subjected to standard tests. The findings of this paper suggest that fly ash/lime bricks can be an alternative product to aerated cellular concrete.

Moisture-Density-Strength-Energy Relationships for Gyratory Compacted Geomaterials

Abstract Laboratory Proctor and vibratory table compaction tests are commonly used to determine moisture-density-compaction energy relationships for soils and are typically limited to one or two compaction energy curves. They do not, however, provide shear strength or stiffness parameters that are commonly used in design and with performance-based specifications. In this study, a gyratory compactor equipped with a pressure distribution analyzer (PDA) was used to rapidly develop moisture-density-shear resistance-compaction energy relationships. Because the PDA equipment involves sensors, data acquisition, and interpretation, repeatability and reproducibility tests were conducted and evaluated using two-way analysis of variance. A wide range of geomaterials was tested: silica sand, crushed limestone sub-base, recycled pavement materials sub-base, and coal combustion products. Comparisons between the gyratory PDA test and conventional laboratory compaction tests and factors affecting the moisture-density-strength-energy relationships were discussed.

Notes on the Potential for the Concentration of Rare Earth Elements and Yttrium in Coal Combustion Fly Ash

Certain Central Appalachian coals, most notably the Fire Clay coal with a REY-enriched volcanic ash fall tonstein, are known to be enriched in rare earth elements. The Fire Clay tonstein has a greater contribution to the total coal + parting REY than would be inferred from its thickness, accounting for about 20%–35% of the REY in the coal + parting sequence. Underground mining, in particular, might include roof and floor rock and the within-seam partings in the mined product. Beneficiation, necessary to meet utility specifications, will remove some of the REY from the delivered product. In at least one previously published example, even though the tonstein was not present in the Fire Clay coal, the coal was enriched in REY. In this case, as well as mines that ship run-of-mine products to the utility, the shipped REY content should be virtually the same as for the mined coal. At the power plant, however, the delivered coal will be pulverized, generally accompanied by the elimination of some of the harder rock, before it is fired into the boiler. Overall, there are a wide range of variables between the geologic sample at the mine and the power plant, any or all of which could impact the concentration of REY or other critical materials in the coal combustion products.

Testing Framework for Analysis of Time-Dependent Behavior of Coal Combustion Products

AbstractCoal combustion products (CCPs) are by-products created when coal is burned for energy production. These products include predominantly fly ash, bottom ash, and flue gas desulfurization (FGD) by-products. These materials can be a viable alternative to natural resources for the construction of engineered fills. Because of the variability in the chemical composition, CCPs require mineralogical, chemical, and mechanical characterization to ensure its applicability as a construction material. Furthermore, CCP characterization should also address the material’s changing properties with time. To date, only limited standards have been proposed to characterize these materials to determine the viability of their use as structural fill. The purpose of this study is to apply a minimal set of practical mechanical and chemical tests that will characterize and predict CCP time-based performance intended for large-volume civil engineering applications such as embankments and mine reclamation. Unconfined compress...

Enhancing carbon sequestration in soil with coal combustion products: a technology for minimising carbon footprints in coal-power generation and agriculture

Coal-fired power generation and agriculture account for more than half of global greenhouse gas emissions, but the coal fly ash (CFA) produced in the former can be a resource for reducing emissions from agriculture to minimise environmental footprints in both industries. Our aim in this study was to test how acidic and alkaline CFA addition could minimise loss of C and N from acidic soil, with or without added manure. We determined composition and structural characteristics of acidic and alkaline CFA for their capacity to adsorb organic carbon, but observed poor adsorption because of low concentrations of cenospheres and unburnt carbon as the primary absorbents in the ash. Addition of CFA had no impact on the loss of carbon or nitrogen from unmanured soil in which concentrations of these nutrients were low. Loss of carbon from manured soil was reduced by 36 % with alkaline ashes and by 3-fold with acidic ashes; while loss of N was 30–50 % lower with acidic ashes, but 28 % higher with alkaline ashes, compared with no ash treatment. The increases in C sparing with CFA addition were achieved not by direct C absorption but by restraining microbial population and respiration, and potentially emissions. Alkaline CFA increased soil pH and if used to substitute just 10 % of lime for ameliorating soil acidity would reduce CO2 emission associated with the mining of the lime and its eventual dissolution in soil by ~ 2.66 Tg or 2.8 % of Australia’s annual agricultural emissions. High concentrations of oxides of phosphorus, silicon, titanium and clay particles in acidic ashes, and oxides of cations in alkaline ashes, were associated with potential for promoting C storage and acidity amelioration in soil.

Strength and Physico-chemical Characteristics of Fly Ash–Bottom Ash Mixture

The quantity of coal combustion products, particularly fly ash (FA) and bottom ash (BA), has been increasing from coal power plants around the world. The major problem of a coal combustion-based power plant is that it produces huge quantities of solid waste. Recently, there have been efforts to use FA and BA together as a mixture in construction works. This paper investigates morphology and chemical and strength characteristics of an FA–BA mixture for various curing periods. Scanning electron microscopy (SEM), X-ray fluorescence (XRF), and consolidated undrained triaxial tests were used to determine the physico-chemical characteristics of the mixture. Based on SEM results, it was found that, with an increasing ratio of BA to FA, the number of irregular particles in the mixture increased. The results of XRF indicated noticeable changes in the surface composition of both FA and BA particles after mixing. The physico-chemical test results indicate the formation of a new gel form product in the mixture, which has been identified as calcium silicate hydrate (C-S-H). From an engineering point of view, the results indicated that the value of modulus of elasticity decreases with increasing BA content, from 30 to 70 %, in the ash mixture. However, the increase in BA from 30 to 70 % did not have any significant effect on the shear strength of the FA–BA mixture.

THE MULTIFACTORIAL ASSESSMENT OF CARCINOGENIC EFFECTS OF ENVIRONMENTAL FACTORS

Objective: Assessment of effects of environmental factors on development of lung cancer. Methods: We applied a multiple factor approach to designing the epidemiologic study. The object of our research was the town of Karpinsk, the Sverdlovsk Region, situated within the environmental radiochemical area with a high radon potential characterized by a moderate level of contamination of the natural environment and high cancer incidence rates among the local population. The case group included 142 lung cancer patients and the control group consisted of 220 people without cancer. We analyzed health effects of 12 biological, social, occupational, and environmental factors. We used the deterministic algorithms of pattern recognition for the multifactor data processing. Results: We have established the power and nature of the effect of each factor under study on development of lung cancer. Using mathematical modeling, we assessed efficiency of hypothetical scenarios of some risk factors correction. Conclusions: Among the lung cancer environmental risk factors in Karpinsk, indoor air pollution with carcinogenic brown coal combustion products was of great importance; the contribution of indoor exposure to radon isotopes was low (0.9 %).

Evaluating Efficiency of Coal Combustion Products (CCPs) and Polyacrylamide (PAM) for Mine Hazard Prevention and Revegetation in Coal Mine Area

Since mine wastes were merely dumped in the mine waste dump, they have produced acid mine drainage (AMD). Therefore, main objective of this study was to evaluate the effect of coal combustion products (CCPs) on heavy metal stabilization and detoxification for mine wastes. Total six treatments for incubation test were conducted depending on mixing method (completely mixing and layered). Also, lysimeter experiment was conducted to examine efficiency of polyacrylamide (PAM) on reduction of mine wastes erosion. Result of incubation test showed that concentrations of soluble aluminium (Al) and iron (Fe) in leachate decreased compared to control. The lowest soluble Al and Fe in leachate was observed in 50% mixed treatment (14.2 and 1.03 mg kg -1 for Al and Fe respectively) compared to control treatment (253.0 for Al and 52.6 mg kg -1 for Fe). The pH of mine wastes (MW) and leachate increased compared to control after mixing with CCPs and ordered as control (MW 6.4, leachate 6.3) -1 ) > MW70CR30LPL (6.7 mg L -1 ) > NT (3.1mg L -1 ) > MW70CR30M (1.6 mg L -1 ) > MW70CR30MPL (1.1 mg L -1 ) > MW70CR30PGM (0.7 mg L -1 ) >MW70CR30LPG (0.5 mg L -1 ) > MW70CR30MPG (0.4 mg L -1 ). Overall, application of CCPs can be environmental friendly and cost-effective way to remediate coal mine wastes contaminated with heavy metals. In addition, use of PAM could help to prevent the erosion coal mine wastes in mine waste disposal area.

Разработка технологии получения сорбентов из продуктов сжигания угля

Разработка технологии получения сорбентов из продуктов сжигания угля

Thermodynamic assessment of the possibility of emission of submicron particles in the process of coal combustion

Methods of chemical thermodynamics of multicomponent reactive systems are used to study the distribution of the most volatile components (potassium and sodium) in the products of combustion of 15 types of coal. The effect of the mineral part of coals and various potassium and sodium compounds on the temperature of their transition into the gas phase is investigated. It is shown that the distribution of potassium and sodium in the products of coal combustion depends on the speciation of these elements in the initial coal; the mineral part composition; the ash content of coals; and the sulfur, potassium, and sodium content of the initial coals.

Research progress about the relationship between nanoparticles silicon dioxide and lung cancer

纳米二氧化硅广泛分布于塑料、橡胶、陶瓷、涂料、粘合剂等众多领域，也是煤、石油等物质的燃烧的产物之一。越来越多的证据显示纳米二氧化硅与呼吸系统病变存在一定的相关性。本文综合国内外研究，对纳米颗粒的肺毒性进行概述，并从纳米二氧化硅的理化性质、暴露条件及其在肺部疾病的致病机制等方面进行综述。

Effect of Solid Fuel Mineral Composition on the Formation of Sour Pulp in Hydro-Slug Removal System of Thermal Power Plants

<p>Researches have been conducted into the causes of acidity of pulp formed in the system of circulating hydraulic ash and slag removal in thermal power plants (TPP) when using coals of Ekibastuz and Karaganda coal fields of the Republic of Kazakhstan. We have carried out a comparative study of combustion of Karazhyra and Maikube coals at the two RK TPPs with BKZ-75-39FB and BKZ-160-100FB steam boilers. For ash collection, wet ash collectors with remounted Venturi tube coagulators have been installed on TPP. In them, a chemical interaction of irrigating water with flue gases occurs, which include CO<sub>2</sub>, SO<sub>2</sub>, SO<sub>3</sub> and ash particles. The ash pulp formed moves to the pipeline, mixes with the slag pulp and is further transported along a tract to the ash dump. We have defined the relationship between the composition of the products of coal combustion and the formation of acidic pulp in the scrubber. Qualitative and quantitative composition of coals and their combustion products have been determined by the methods of X-ray and X-ray fluorescence analysis. As the analysis showed, the main components of ash and slag materials are the oxides SiO<sub>2</sub>, Al<sub>2</sub>O<sub>3</sub>, Fe<sub>2</sub>O<sub>3</sub>, CaO, MgO, K<sub>2</sub>О, Na<sub>2</sub>O. In the wet ash collectors gaseous substances present in flue gases, are dissolved and hydrolysed in irrigating water. While hydroremoving ash and slag, the compounds are dissolved in water and undergo hydrolysis. Oxides SiO<sub>2</sub>, SO<sub>2</sub>, TiO<sub>2</sub>, P<sub>2</sub>O<sub>5</sub> are hydrolyzed into acid, oxides CaO, MgO, K<sub>2</sub>O and Na<sub>2</sub>O – into base, Al<sub>2</sub>O<sub>3</sub>, Fe<sub>2</sub>O<sub>3 </sub>– into amphoteric compounds. Chemical analysis of ash and slag pulp formed after Karazhyra coal combustion has been carried out. Calculation of the acidity of ash and slag material has been performed. Karazhyra coal ash is more acidic in nature. A lower content of amphoteric oxides in Maikube coal appears to be the cause of the pulp formation, with a higher pH. With X-ray diffraction method, the nature of combinations of metal oxides in the samples of coal, slag and ash have been determined. </p>

Latest Permian chars may derive from wildfires, not coal combustion

The Permian-Triassic boundary extinction event was the largest biological crisis of the Phanerozoic. One of the principle triggers for the mass extinction is thought to be greenhouse warming resulting from the release of CH 4 from basalt-coal interaction during the extensive Siberian Traps (Russia) eruptions. Observations of organic matter interpreted to be coal combustion products (fly ash) in latest Permian marine sediments have been used to support this hypothesis. However, this interpretation is dependent upon vesicular chars being fly ash (coal combustion derived) and not formed by alternative mechanisms. Here we present reflectance microscopy images of vesicular chars from Russian Permian coals, and chars from modern tundra, peatland, and boreal forest fires, to demonstrate that despite a difference in precursor fuels, wildfires are capable of generating vesicular chars that are morphologically comparable to end-Permian fly ash. These observations, coupled with extensive global evidence of wildfires during this time interval, call into question the contribution of coal combustion to the end-Permian extinction event.

Application of thermal desorption for the identification of mercury species in solids derived from coal utilization

The speciation of mercury is currently attracting widespread interest because the emission, transport, deposition and behaviour of toxic mercury species depend on its chemical form. The identification of these species in low concentrations is no easy task and it is even more complex in coal combustion products due to the fact that these products contain organic and mineral matter that give rise to broad peaks and make it difficult to carry out qualitative and quantitative analysis. In this work, a solution to this problem is proposed using a method based on thermal desorption. A sequential extraction procedure was employed for the comparison and validation of the method developed. Samples of fly ashes and soils were analyzed by both of these methods, and thermal desorption was found to be an appropriate technique for mercury speciation. Even in the case of low mercury contents, recovery percentages were close to 100%. The main mercury species identified in the samples studied were HgS and, to a lesser extent, HgO and HgSO4. In addition, although the presence of mercury complexes cannot be demonstrated, the desorption behaviour and sequential extraction results suggest that this element might be associated with the mineral matrix or with carbon particles in some of the solids.

Natural attenuation of coal combustion waste in river sediments

The weathering of coal combustion products (CCPs) in a lotic environment was assessed following the Tennessee Valley Authority (Kingston, TN) fly ash release of 2008 into surrounding rivers. Sampled materials included stockpiled ash and sediment collected from 180 to 880days following the release. Total recoverable concentrations of heavy metals and metalloids in sediment were measured, and percent ash was estimated visually or quantified by particle counts. Arsenic and selenium in sediment were positively correlated with percent ash. For samples collected 180days after the release, total concentrations of trace elements downstream of the release were greater than reference levels but less than concentrations measured in stockpiled ash. Total concentrations of trace elements remained elevated in ash-laden sediment after almost 2.5years. A sequential extraction procedure (SEP) was used to speciate selected fractions of arsenic, copper, lead, nickel, and selenium in decreasing order of bioavailability. Concentrations of trace elements in sequentially extracted fractions were one to two orders of magnitude lower than total recoverable trace elements. The bulk of sequentially extractable trace elements was associated with iron-manganese oxides, the least bioavailable fraction of those measured. By 780days, trace element concentrations in the SEP fractions approached reference concentrations in the more bioavailable water soluble, ion exchangeable, and carbonate-bound fractions. For each trace element, the percentage composition of the bioavailable fractions relative to the total concentration was calculated. These SEP indices were summed and shown to significantly decrease over time. These results document the natural attenuation of leachable trace elements in CCPs in river sediment as a result of the loss of bioavailable trace elements over time.

Understanding selected trace elements behavior in a coal-fired power plant in Malaysia for assessment of abatement technologies

The Proposed New Environmental Quality (Clean Air) Regulation 201X (Draft), which replaces the Malaysia Environmental Quality (Clean Air) 1978, specifies limits to additional pollutants from power generation using fossil fuel. The new pollutants include Hg, HCl, and HF with limits of 0.03, 100, and 15 mg/N-m3 at 6% O2, respectively. These pollutants are normally present in very small concentrations (known as trace elements [TEs]), and hence are often neglected in environmental air quality monitoring in Malaysia. Following the enactment of the new regulation, it is now imperative to understand the TEs behavior and to assess the capability of the existing abatement technologies to comply with the new emission limits. This paper presents the comparison of TEs behavior of the most volatile (Hg, Cl, F) and less volatile (As, Be, Cd, Cr, Ni, Se, Pb) elements in subbituminous and bituminous coal and coal combustion products (CCP) (i.e., fly ash and bottom ash) from separate firing of subbituminous and bituminous coal in a coal-fired power plant in Malaysia. The effect of air pollution control devices configuration in removal of TEs was also investigated to evaluate the effectiveness of abatement technologies used in the plant. This study showed that subbituminous and bituminous coals and their CCPs have different TEs behavior. It is speculated that ash content could be a factor for such diverse behavior. In addition, the type of coal and the concentrations of TEs in feed coal were to some extent influenced by the emission of TEs in flue gas. The electrostatic precipitator (ESP) and seawater flue gas desulfurization (FGD) used in the studied coal-fired power plant were found effective in removing TEs in particulate and vapor form, respectively, as well as complying with the new specified emission limits.Implications:Coals used by power plants in Peninsular Malaysia come from the same supplier (Tenaga Nasional Berhad Fuel Services), which is a subsidiary of the Malaysia electricity provider (Tenaga Nasional Berhad). Therefore, this study on trace elements behavior in a coal-fired power plant in Malaysia could represent emission from other plants in Peninsular Malaysia. By adhering to the current coal specifications and installation of electrostatic precipitator (ESP) and flue gas desulfurization, the plants could comply with the limits specified in the Malaysian Department of Environment (DOE) Scheduled Waste Guideline for bottom ash and fly ash and the Proposed New Environmental Quality (Clean Air) Regulation 201X (Draft).

Determination of As and Se in coal and coal combustion products using closed vessel microwave digestion and collision/reaction cell technology (CCT) of inductively coupled plasma mass spectrometry (ICP-MS)

Toxic elements arsenic and selenium in coal are of great concern mainly because of their adverse effects on human health during coal combustion. This paper describes the concentration determination of As and Se in coal and coal combustion products (CCPs), performed by collision/reaction cell technology (CCT) of inductively coupled plasma mass spectrometry (ICP-MS; collectively ICP-CCT-MS) after closed vessel microwave digestion. The reagents for 50-mg coal sample digestion are 2-ml 40% (v/v) HF and 5-ml 65% (v/v) HNO3 but for the CCP samples, the reagents include 5-ml 40% HF and 2-ml 65% HNO3. To significantly diminish the argon-based interferences at mass to charge ratios (m/z) 75 (40Ar35Cl) and 78 (40Ar38Ar), a helium and hydrogen mixture was used in the optimized hexapole collision cell. The results showed that CCT technology can effectively diminish the spectral interferences of the Ar-based polyatomic ions 40Ar35Cl and 40Ar38Ar to 75As and 78Se, respectively. The method detection limit of As and Se is 0.024 and 0.095μg/l, respectively, and their linearity of the calibration curves in the range 0–100μg/l has a determination coefficient r2>0.9999. The determination of As and Se in NIST standard reference materials of coal and fly ash samples showed that ICP-CCT-MS plus closed vessel microwave digestion is a reliable method for concentration determination of the two elements in coal and CCPs.