Distribution Of Fly Ash Research Articles

Influence of fly ash filler on the mechanical properties and water absorption behaviour of epoxy polymer composites reinforced with pineapple leaf fibre for biomedical applications.

This study explores the impact of fly ash (FA) filler on the mechanical, morphological, and water absorption properties of pineapple leaf fibre (PALF)-reinforced epoxy composites for biomedical applications. PALF, sourced from abundant agricultural waste, offers a sustainable alternative to synthetic fibres. Employing the hand layup process, varying wt% of FA (3%, 6%, and 9%) are incorporated into PALF-reinforced epoxy composites with different PALF concentrations (10%, 20%, and 30%). Mechanical assessments, including impact, flexural, and tensile strength, reveal that the introduction of up to 6 wt% FA enhances tensile strength by 65.3%, reaching its peak at this concentration. Flexural strength also improves by 31.9% with 6 wt% FA, while impact resistance reaches its maximum (74.18% improvement) at 9 wt% FA. Water absorption measurements demonstrate a decrease with increased FA content and exposure period, indicating enhanced water resistance. Scanning electron microscopy confirms the uniform distribution of FA, contributing to improved mechanical characteristics and water resistance. Optimality tests using Taguchi and response surface methodology (RSM) further confirm the experimental outcomes, emphasizing the potential of FA to enhance natural fibre-reinforced composites. This research suggests FA as a promising filler to elevate mechanical performance and water resistance in environmentally friendly composites.

Particle Size Distribution and Enrichment of Alkali and Heavy Metals in Fly Ash on Air and Oxy-Fuel Conditions from Sludge Combustion

Comparative tests in air and oxy-fuel combustion were conducted in a 30 kWth circulating fluidized bed (CFB) pilot plant for waste sludge combustion. General combustion characteristics of the CFB, such as pressure profiles, temperatures along the bed, and flue gas composition, were different under the air and oxy-fuel conditions. At the bottom and in the fly ash, alkali and heavy metals had different distributions under the air and oxy-fuel combustion conditions. The particle size distribution in fly ash from air combustion was dominated by coarse particles, over 2.5 μm in size, whereas with oxy-fuel combustion, most particles were submicron in size, approximately 0.1 μm, and a smaller quantity of coarse particles, over 2.5 μm in size, formed than with air combustion. Mass fractions of Al, Ca, and K, below 2.5 μm in size, were found in the ashes from oxy-fuel combustion and in higher quantity than those found in air combustion. Submicron particle formation from Cr, Ni, Cu, and Zn in the fly ash occurred more during oxy-fuel combustion than it did in air combustion.

Numerical simulation of ash erosion in the selective catalytic reduction catalyst of power plant boiler

The selective catalytic reduction (SCR) catalyst of a 660 MW ultra-supercritical once-through boiler denitrification system suffered severe abrasion, causing the denitrification system to fail. Statistics showed the abrasion area focused on near side of the boiler. The formation mechanism of the catalyst abrasion is analyzed using general purpose computational fluid dynamics (CFD). The simulation results are consistent with the actual test data. It reveals that the catalyst abrasion is likely to be caused by the nonuniformity distribution of the fly ash particle field. The fly ash distribution and the gas velocity in different cases were obtained. Under the best case, the impact device can ensure fly ash particles in the upper part of catalyst move to the far boiler side of catalyst. It is shown that the flow field and fly ash particle distribution greatly improved after computation of the optimization.

Characteristics of particulate emissions from coal char combustion: Char fragmentation and ash coalescence behaviors

Air pollution from fossil fuel combustion motivated the extensive and in-depth investigation on particulate matter (PM) to meet the stringent emission norms. The relationship between char fragmentation/mineral coalescence and PM formation is elucidated in this paper. To separately investigate their contributions to PM formation, the effects of particle bursting during devolatilization and fragmentation of excluded minerals have been stripped off. We prepared size-graded and density-fractionated chars with varying ash content levels and conducted combustion experiments in a drop-tube furnace at 1300/1600/1800 K. The mass particle size distributions (PSDs) of collected ash were measured by an Electrical Low Pressure Impactor (for PM10) and a laser particle-size analyzer (for PM10+). The micro- morphologies and elemental compositions analyses were also shown for particles of different sizes. The results indicate that char fragmentation significantly increases the number of ash particles in fine-fragmentation mode (FFM), and the ash peak in the coarse mode comes from the char particles that show fewer fragmentation behaviors. Dense char structure disadvantages char fragmentation but enhances coalescence of included minerals. The distribution of fly ash at 1600/1800 K exhibits bi-modal with two peaks around 10 and 105 μm, while the distribution at 1300 K/50%O2 exhibits uni-modal with one peak. This can be well explained by the percolation theory that the char combustion in the kinetically-limited regime is dominated by uniform fragmentation, while particles at 1600/1800 K mainly undergo perimeter fragmentation. The effect of ash content is more related to the mineral grains distributions within the char particles.

Flue gas-to-ash desulfurization of combustion of textile dyeing sludge: Its dependency on temperature, lignocellulosic residue, and CaO

• Flue gas-to-ash desulfurization of textile dyeing sludge combustion was studied. • Spent mushroom substrate and calcium oxide reduced conversion of sulfur to flue gas. • Spent mushroom substrate enhanced sulfur retention in fly ash at above 800 °C. • Potassium and phosphorus in spent mushroom substrate drove sulfur distribution. Flue gas-to-ash controls on sulfur (S) species of the combustion of textile dyeing sludge (TDS) are pivotal in the achievement of circular and cleaner economies. This experimental study aimed to characterize S transformations in TDS as a function of temperature (600–1000 °C) and blend ratios of spent mushroom substrate (SMS) and calcium oxide (CaO) through thermodynamic equilibrium simulations. The conversion ratio of S to flue gas from the mono-combustion of TDS rose by 29.7% between 600 and 1000 °C and was 92.9% at 1000 °C. The increasing sulfur dioxide (SO 2 ) emission with the high temperature occurred from the decomposition of sulfates. The conversion of S to SO 2 decreased significantly with an increase in SMS from 10 to 50% and enhanced the S distribution in fly ash. Potassium and phosphorous in SMS appeared to play a significant role in the conversion of S. The addition of CaO exhibited a good desulfurization performance, with the S content of ash peaking at 5.2% at 800 °C with 7% CaO. The desulfurization efficiency of CaO highly depended on the temperature and blend ratios. The addition of SMS facilitated the agglomeration to form large particles at 1000 °C and formed more micro pores on their surfaces. Our equilibrium simulations pointed to the important role of CaO-assisted co-combustion versus mono-combustion of TDS in the S retention as well as to the enhanced decomposition of calcium sulfate (CaSO 4 ) by SMS. Chlorine had a better affinity toward potassium to promote the release of gaseous potassium chloride (KCl) which in turn appeared to react with SO 2 in flue gas and formed sulfates through sulfation reaction.

Desulfurization using limestone during sludge incineration in a fluidized bed furnace: Increased risk of particulate matter and heavy metal emissions

Incineration of sludge can be an effective method to minimise waste whilst producing useful heat. However, incineration can cause secondary pollution issues due to the emission of SO2, therefore a set of experiments of sludge incineration in a bubble bed furnace were conducted with limestone addition to study desulfurization of sludge incineration flue gas. As expected, over 93% emission of SO2 was reduced with limestone addition, and that of CO and NOx were increased and decreased respectively when the fuel feeding rate raised. The distribution of fly ash was also increased by raising the fuel feeding rate due to increasing fragmentation of the ash. However, distributions of PM2.5 and heavy metals in submicron particles have dramatically increased with limestone desulfurization. The mechanism was revealed by SEM and EDS statistical analysis, indicating that the reaction between aluminosilicate and calcium made particles agglomerate and eutectic mixtures form, these larger ash particles were found to divide between collection as cyclone ash and fragmentation into finer particles that bypassed the cyclone. Those fine particles provided more surface area for heavy metal condensation. Furthermore, it was found that the reaction mechanism for semi-volatile metals involved them being released from the sludge and forming PM1 particles due to the vaporization-condensation mechanism, leading to higher emission of PM1 and distribution of heavy metals in PM1. Thus, it should be considered that there may actually be higher emission risks of PM and heavy metal emissions when aiming to desulfurize a flue gas using Ca-based minerals in certain circumstances.

Distribution of Some Ecotoxic Elements in Fuel and Solid Combustion Residues in Poland

The purpose of this paper is to assess the content and distribution of some elements in coal from two bituminous coal basins and in fly ash and slag derived from combustion of the coals in six power plants in Poland. The petrographic composition and distribution of elements were characterized in the tested samples, using reflected light microscope, X-ray powder diffractometer, inductively coupled plasma atomic emission spectroscopy, and scanning electron microscope with energy dispersive X-ray. The highest content of elements in coal occurs in siderite. In Al-Si particles, as well as in magnetite with skeletal and dendritic structure crystallized on the surface of Al-Si microspheres or cenospheres included in fly ash size < 0.05 mm and in the magnetic fraction of slag, the highest content of elements was noted. Due to the content of elements, fly ash and slag were considered to be neutral for the soil environment. Correlations, which have not been described before, have been observed between the likely mode of binding of some elements in coal and their distribution in fly ash and slag. These correlations could be of particular value when predicting the content and distribution of elements in combustion residues and in the assessment of their environmental toxicity.

Arsenic distribution and pathway scenarios for sediments and water in a peri-urban Mongolian small-scale coal mining area (NalaikhDistrict, Ulaanbaatar).

The distribution of arsenic (As) in environmental compartments is investigated in the Nalaikh Depression of N-Mongolia. In Nalaikh, lignite coal is mined by artisanal small-scale mining (ASM) approaches. Because As is often associated with sulfuric minerals in coal, it was hypothesized that enrichment of As is related to coal ASM. A second hypothesis considered coal combustion in power plants, and stoves are a key source of As in the local environment. Three mobilization and distribution scenarios were developed for potential As pathways in this semiarid environment. About 43 soil and 14 water sites were analyzed for As concentrations and meaningful parameters in soil and water. About 28 topsoil samples were analyzed in surface-subsurface pairs in order to identify potential eolian surface enrichment. Additionally, fluvial-alluvial sediments and geogenic and anthropogenic deposits were sampled. Water was sampled as surface water, groundwater, precipitation, and industrial water. Results show that As does not pose a ubiquitous risk in the Nalaikh Depression. However, locally and specifically in water, As concentrations may exceed the WHO guideline value for drinking water by up to a factor of 10. A carefully selected sampling strategy allows the evaluation of the distribution scenarios, which reveals a combination of (a) geogenic As in groundwater and distribution via surface water with (b) anthropogenic As redistribution via eolian pathways. An immediate linkage between As redistribution and coal mining is not evident. However, As distribution in fly ash from coal combustion in the local power plant and yurt settlements is the most likely As pathway. Hence, the results indicate the potential influence of diffuse, low-altitude sources on As emission to the environment. As such, this study provides a good example for As distribution under semiarid climate conditions influenced by geogenic and anthropogenic factors.

Effects of fly ash on the properties and microstructure of alkali-activated FA/BFS repairing mortar

This article presents the effects of fly ash (FA) on the properties and microstructures of alkali-activated FA/BFS repairing mortars. Firstly, the characteristics (chemical and mineral compositions, particle size distribution or specific surface area) of FAs were investigated. Two factors (the content of amorphous phases (CAP) and particle size distribution (PSD) or specific surface area) were defined as the two major variables and its effects on the properties (mechanical strength, flow value, and shrinkage) of alkali-activated FA/BFS repairing mortars were studied. The results indicated that the mechanical strength of alkali-activated FA/BFS mortar depended more on the content of amorphous phases since it facilitated the degree of geopolymerization reaction and the formation of products. IIFA/BFS exhibited the highest compressive, flexural, and interfacial flexural-tensile strength due to its higher content of amorphous phases. However, the particle size distribution of FA had little contribution on mechanical strength but effected the flow value and drying shrinkage more apparently. Additionally, it’s also found that except the mechanical interlocking and Van der Waals forces, the chemical bonding also presented between the repairing systems and substrate. That’s why the alkali-activated FA/BFS mortar exhibited higher bonding strength and was suitable for repairing concrete.

Nano-Scale Rare Earth Distribution in Fly Ash Derived from the Combustion of the Fire Clay Coal, Kentucky

Fly ash from the combustion of eastern Kentucky Fire Clay coal in a southeastern United States pulverized-coal power plant was studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). TEM combined with elemental analysis via energy dispersive X-ray spectroscopy (EDS) showed that rare earth elements (REE; specifically, La, Ce, Nd, Pr, and Sm) were distributed within glassy particles. In certain cases, the REE were accompanied by phosphorous, suggesting a monazite or similar mineral form. However, the electron diffraction patterns of apparent phosphate minerals were not definitive, and P-lean regions of the glass consisted of amorphous phases. Therefore, the distribution of the REE in the fly ash seemed to be in the form of TEM-visible nano-scale crystalline minerals, with additional distributions corresponding to overlapping ultra-fine minerals and even true atomic dispersion within the fly ash glass.

Compression and corrosion behaviour of sintered copper-fly ash composite material

An attempt has been made to reinforce Copper (Cu) with low density material Fly Ash (FA) to form Cu–FA composite material through Powder Metallurgy (P/M) route. Samples of 3, 6 and 9 weight percentage of FA in Cu matrix were prepared. Scanning electron microscopy analysis was used to study the morphology of the composite materials. The x-ray diffraction analysis was used to characterize the elemental composition of composite powder. Energy-dispersive spectroscopy (EDS) mapping was used to find the homogeneous distribution of FA in Cu matrix. Mechanical behavior of the Cu–FA composite material was studied using Vickers hardness and compression test. The mechanism model for decrease in compressive strength of Cu–FA composite material was identified as boundary slip. The corrosion behavior of Cu–FA composite material in acidic (1N HCl) and in sea water media are studied. Electrochemical polarization test was used to carry out the corrosion studies on Cu–FA composite material in acidic media. The increase in Polarization Resistance (Rp = 68.6499 × 10−4 Ω cm2 in acidic media and Rp = 68.75327 10−4 Ω cm2 in sea water) of Cu-9FA evidences that increase in weight percentage reinforcement of FA in Cu matrix decreases the corrosion rate in both acidic and sea water media. The increase in charge transfer resistance (Rct = 1142 Ω cm2) of Electrochemical Impedance Spectroscopy (EIS) test authenticates that the corrosion resistance of Cu-9FA is healthier than pure Cu. It was observed that improved corrosion resistance and good mechanical properties are obtained for 9% FA reinforced Cu composite material.

Evolution of Fly Ash Aluminosilicates in Slagging Deposition during Oxy-Coal Combustion Investigated by 27Al Magic Angle Spinning Nuclear Magnetic Resonance

Boiler slagging jeopardizes the safe and economic operation of coal-fired boilers. Aluminosilicates are the most abundant substances in fly ash and boiler slagging deposits. In order to understand the roles of the fly ash aluminosilicates in slagging, studying their evolution in the ash deposition is invaluable. In this work, 27Al magic angle spinning nuclear magnetic resonance (MAS-NMR) and X-ray diffraction were used to measure the aluminum coordination and the phase distribution in fly ash and ash deposit samples of two USA thermal coals [Powder River Basin (PRB) sub-bituminous coal and Illinois coal] and their blended coal prepared in an oxy-coal combustion experiment apparatus. Morphology and constituents of these samples were also analyzed using scanning electronic microscopy. The results show that, for all fly ashes and ash deposits, the aluminum exists only in aluminosilicates and is mainly four-coordinate aluminum [Al(IV)], with a small amount in six-coordinate aluminum Al(VI) (chemical shift: 2....

Fly-ash-incorporated electrospun zinc oxide nanofibers: Potential material for environmental remediation

Fly ash (FA), a solid waste generated in thermal power plants, is considered an environmental pollutant. Therefore, measures must be taken to dispose of FA in an environmentally friendly manner. In this paper, an electrospinning technique was employed to incorporate FA particles onto zinc oxide nanofibers (ZnO NFs), and the product (FA/ZnO composite) was used for the removal of methylene blue (MB) from the water. Herein, ZnO NFs may serve as effective semiconductor photocatalysts and provide sufficient surface area for FA, while the FA particles serve as an effective adsorbent. The adsorption capacity and photocatalytic efficiency of the as-synthesized nanocomposite fibers were enhanced compared to those of the pristine ZnO NFs, and this result is attributed to the uniform distribution of FA on the surface of the ZnO NFs. The as-synthesized nanocomposite could have great significance in wastewater treatment.

Microstructure, hardness and wear behavior of AZ31 Mg alloy – fly ash composites produced by friction stir processing

Recently, magnesium (Mg) and its alloys are gaining tremendous attention as promising light weight metals for structural applications in automobile and aerospace industries. AZ (aluminium and zinc) series is one of such most widely used commercial Mg alloy system. On the other hand, metal matrix composites (MMCs) are a class of modern engineered materials which exhibit hybrid properties compared with their base metals. Therefore, in the present study, AZ31 Mg alloy was selected as matrix and fly ash as dispersing phase with an aim to produce MMCs by friction stir processing (FSP). Basically FSP is a solid state processing technique which does not result the work piece to melt and offers many advantages. Surface composites were successfully produced by FSP and the distribution of fly ash was found to be uniform at the surface and non-uniform in the subsurface regions. Microstructural observations have clearly showed fine grain structure in the processed zone. Compared with annealed AZ31, a 30% increase in hardness was observed for the composites. However, a significant variation in the hardness was observed across the processed region (advancing, nugget and retreating regions). Grain refinement and the presence of fly ash are the prime reasons which played important role behind the increased hardness. From the wear studies, coefficient of friction was observed as decreased for the sample collected at the retreating side compared with unprocessed and sample collected from nugget zone. It can be understood from the preliminary observations that the AZ31-fly ash composites can be successfully produced in solid state by FSP and the effect of fly ash as dispersing phase on enhancing the hardness and wear properties is promising.

Rare Earth Element Distribution in Fly Ash Derived from the Fire Clay Coal, Kentucky

Fly ash was collected from individual mechanical and electrostatic precipitator (ESP) hoppers at a 130-MW pulverized-coal utility unit burning a southeastern Kentucky moderate- to high-S Pennsylvanian Fire Clay coal. The fly ash particle size is generally similar within each row of the mechanical and ESP hoppers, with the mean particle diameter decreasing from \>36 µm in the mechanical hoppers to 6 µm in the last ESP row. Rare earth element (REE)-bearing phases occur within fine minerals and, possibly, as part of the fly ash glass phase. Transmission electron microscopy was used to identify Y-Ce-Nd-La-bearing regions within a glassy matrix. Y- and U-bearing zircons were also found in the fly ash. Total REE plus yttrium (REY) occupies a narrow range from 719 to 775 ppm, showing an overall lack of partitioning of the REY elements with respect to particle size and temperature in ash collection systems. The heavy REE increase and the light REE/heavy REE ratio decreases from the mechanical hoppers through ESP rows.

EFFECT OF BALL MILLING OF FLY ASH PARTICLE SIZE ON FOAM STABILIZATION FOR EOR APPLICATIONS

In enhanced oil recovery (EOR), nanoparticles have gained the potential to improve foam stability. In this study, the potential of fly ash to produce stable foam by using shaker was studied. Fly ash nanoparticles were developed by the mechanical treatment using ball mill. Sample to ball ratio of 1 to 10 was applied to investigate the effect of ball milling on particle size distribution of fly ash. The mechanically activated fly ash was mixed at various concentrations (ppm) with the anionic foaming surfactants AOS14-16. Foam stability tests were performed at ambient conditions by making solution through shaker. Stable foams were generated using varies types of fly ash particles. It was observed that the small sized fly ash has more potential towards foam forming ability and foam stability. Therefore, the mechanically activated fly ash resulted in a considerably increased EOR.

Properties of Aluminum Matrix Composite (AMCs) for Electronic Packaging

In this study, the microstructure of prepared AMCs with the homogenous distribution of fly ash analyzed using optical microscope. The microstructure having refinement of structure with the decreasing of Si-needle structure and increasing the area of eutectic α-Al matrix as shown in Figure 3. Besides, as the increasing amount of fly ash incorporated, there are more petal-like dark structure existed in the microstructure. The density of the AMCs decreased as the incorporation of fly ash increased. While the hardness strength of the AMCs increased with the incorporation of fly ash. The addition of fly ash particles improved the physical and mechanical properties of the AMCs.

Rock magnetic finger-printing of soil from a coal-fired thermal power plant.

We present seasonal rock magnetic data for 48 surficial soil samples collected seasonally around a coal-fired thermal power plant on the southwest coast of India to demonstrate how fly ash from the power plant is transported both spatially and seasonally. Sampling was carried out during pre-monsoon (March), early-monsoon (June), monsoon (September) and post-monsoon (December) seasons. Low- and high-frequency magnetic susceptibility (χlf and χhf), frequency-dependent magnetic susceptibility (χfd), χfd %, isothermal remanent magnetization (IRM), "hard" IRM (HIRM), saturation IRM (SIRM) and inter-parametric ratios were determined for the samples. Scanning electron microscopy (SEM) was used on limited number of samples. NOAA HYSPLIT MODEL backward trajectory analysis and principal component analysis were carried out on the data. Fly ash samples exhibit an average HIRM value (400.07 × 10(-5) Am(2) kg(-1)) that is comparable to that of soil samples. The pre- and post-monsoon samples show a consistent reduction in the concentration of magnetically "hard" minerals with increasing distance from the power plant. These data suggest that fly ash has indeed been transported from the power plant to the sampling locations. Hence, HIRM may perhaps be used as a proxy for tracking fly ash from coal-fired thermal power plants. Seasonal data show that the distribution of fly ash to the surrounding areas is minimum during monsoons. They also point to the dominance of SP magnetite in early-monsoon season, whereas magnetic depletion is documented in the monsoon season. This seasonal difference is attributable to both pedogenesis and anthropogenic activity i.e. operation of the thermal power plant.

CFD analysis on the catalyst layer breakage failure of an SCR-DeNOx system for a 350 MW coal-fired power plant

Selective catalytic reduction as one of the secondary NOx control technologies is widely used in industrial sources including coal-fired power plants and large boilers. The performance of an SCR-DeNOx system is sensitive to the installment of its components such as turning vanes and hybrid grids. In this work, three-dimensional CFD simulations are carried out to analyze the breakage failure of an SCR-DeNOx system for a certain 350MW coal-fired power plant. Research results are consistent with the phenomena that occur in the industrial application. It reveals that the breakage failure in the industrial application is likely to be caused by the inappropriate installation of the turning vane 3 locating closest to the catalyst, especially the angle of the turning vane 3. The analysis further shows that the lifetime or the breakage of the catalyst layers depends highly on the gas velocity, the fly ash distribution and its particle velocity.

Effect of fly ash size fraction on the potential to neutralise acid mine drainage and rheological properties of sludge

AbstractLarge quantities of fly ash (FA) are generated annually in South Africa and most of it is disposed in landfills and ash dams. Previous studies indicated that FA can be used to treat acid mine drainage (AMD), another waste stream commonly found in the minerals industry. Moreover, encouraging results were obtained from the studies carried out on the sludge (referred as solid residues (SR) hereafter) recovered from FA-AMD treatment as a suitable mine backfill material. Particle size distribution (PSD) of FA plays an important role in the AMD treatment quality and viscosity of the SR that can be used directly for backfill purposes. In this study, we have investigated the effect of PSD of FA on AMD neutralisation and metal removal. This work also looked at the effect of PSD on the rheology of the SR. Neutralisation experiments indicated that the higher fines fraction enhances the treatment of AMD by reducing the time taken to increase the pH to a minimum of 7. Moreover, FA with higher fines fraction ha...