Characteristics Of Ash Research Articles

Investigation into the Enhancement Characteristics of Fly Ash and Polypropylene Fibers on Calcium Carbide-Residue-Stabilized Soil

The recycling and reuse of waste materials is an important part of promoting sustainable development. Encouraged by cleaner production and a circular economy, the introduction of calcium carbide residue (CCR) for the stabilization of soil foundations has become a hot topic in the road engineering industry. Aiming at the efficient application of CCR-stabilized soils, the optimization of the material composition was focused on in this work. Fly ash and polypropylene fibers were introduced into the preparation of CCR-stabilized soils, and their effects on the mechanical properties and water stability were tested. The findings highlight that the strength of fly-ash–carbide-residue-stabilized soil was higher than that of carbide-residue-stabilized soil at the same curing age. Furthermore, the unconfined compressive strength, splitting strength, and water stability of CCR–fly-ash-composite-stabilized soil initially increased and then decreased with a rise in polypropylene fiber content. The peak values of confining compressive and splitting strength were observed when the polypropylene fiber content was 1.2‰, while the water stability coefficient A reached its peak value at 0.8‰. From the standpoint of the comprehensive performance improvement and economy of composite-stabilized soil, it is advised that the dosage of polypropylene fibers falls within the range of 0.8–1.2‰. The engineering technical indexes of polypropylene-fiber–CCR-composite-stabilized soil fulfilled the requirements of the specification and had a satisfactory effect on delaying the cracking of the specimen. It is expected that this investigation will provide support for the resource utilization of CCR and the sustainable development of road construction.

Comparison of the Analytical Performance of Inductively Coupled Plasma Mass Spectrometry and Instrumental Neutron Activation Analysis Techniques in the Elemental Analysis of Coal Fly Ash

Inductively coupled plasma mass spectrometry (ICP-MS) and instrumental neutron activation analysis (INAA) were applied to study the elemental content of coal combustion residues. Both methods’ analytical applicability and suitability for this type of material were described in detail. A certified reference material, fine fly ash (CTA-FFA-1), was used to examine the capabilities and validation of both methods. A comparison study allowed for the modification of the procedures for these materials (previously elaborated in the Institute of Nuclear Chemistry and Technology), resulting in more accurate data with lower uncertainty. We highlighted that INAA and ICPs complemented each other in the analysis of coal and coal combustion residues. The digestion procedure was an integral part of the measurement and affected the environmental analysis results. Both methods were applied to the chemical characteristics of coal ashes from household furnaces. The hard coal was from Polish, Columbian, and Kazakh mines. The majority of elements had similar concentrations, independently of coal origin. Because ash from domestic coal combustion is used as a fertilizer or an anti-icing agent, we assessed the potential environmental impact via leaching experiments (according to PN-EN 12457-2). The potential risk of soil contamination due to ash dumping around the house and its surroundings was determined as insignificant (for the elements investigated).

Acid controlled washing of municipal solid waste incineration fly ash: Extraction of calcium inhibiting heavy metals and reaction kinetics

Washing method has attracted much attention in the research of municipal solid waste incineration (MSWI) fly ash treatment and resource utilization. However, the controlled leaching of heavy metals and the extraction of recyclable calcium in the washing process are still blank. Acid controlled washing was conducted with different acids, concentrations, times and temperatures to extract calcium while inhibiting heavy metals. The mechanism was investigated by reaction kinetics calculation and washed fly ash characterization. The high Ca concentration of 37,420 mg/L while the low heavy metal concentrations of around or <1 mg/L were achieved at 25 °C for 60 min under a liquid-solid ratio (L/S) of 3/1 in 1.5 M HCl. The reaction kinetics of acid controlled washing conformed the layer diffusion control. The results of X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrum (EDS) analysis indicated that the rate-limiting step was the diffusion of ions through the product layer. Simultaneously, the washing solution enriched in Ca, Na and K and the washed fly ash, which met the standard requirements (HJ 1134–2020) for leach toxicity, both had the potential for further resource utilization.

COMPRESSIVE STRENGTH CHARACTERISTICS OF PAWPAW LEAF ASH AND BAMBOO LEAF ASH BLENDED CEMENT CONCRETE

The study determined the physical properties of pawpaw leaf ash and bamboo leaf ash blended cement concrete, the effect of curing age on compressive strength characteristics of pawpaw leaf ash and bamboo leaf ash blended cement concrete, and the effect of percentage replacement of cement with pawpaw leaf ash and bamboo leaf ash blended cement concrete on compressive strength. 100 ×100×100 mm cubes specimens were cast, and the concrete compressive strengths were determined at 7, 14, 21 and 28 days of curing. The control sample, with 0% BLA and PLA replacement, exhibited the highest strength at 28 days but the lowest at 7 days. The sample with 5% BLA and PLA replacement showed an increase in strength at 14 days, a decrease at 21 days, and another increase at 28 days, with the highest strength observed at 14 days. On the other hand, the samples with 10%, 15%, and 20% BLA and PLA replacement demonstrated a consistent increase in strength, although a decrease in strength was observed at 28 days. The experiment revealed that the highest compressive strength was achieved at 28 days with 0% BLA and PLA replacement, while the lowest compressive strength was observed at 7 days with 20% BLA and PLA replacement. These findings indicate that the rate of strength development in BLA and PLA blended cement concrete is slower during the early curing period (7 days) but accelerates during later ages (14 days and 21 days), with a slight decrease at 28 days. In contrast, the control sample without BLA and PLA replacement exhibited slow strength development initially (7 days) but showed faster progress at later ages. Based on the test results, 20% replacement was found to be the optimum level for both compressive strength and workability of concrete with cement partially replaced with BLA and PLA.

The impacts of CO2 mineralization reaction on the physicochemical characteristics of fly ash: A study under different reaction conditions of the water-to-solid ratio and the pressure of CO2

Utilizing fly ash (FA) directly to mineralize CO2 and injecting carbon sequestration products into goafs of coal mines is a novel and promising technology. The impact mechanisms of CO2 direct mineralization reactions on the characteristics of key groups, physical phases, surface micromorphology, particle size and pore structure of FA are discussed systematically in detail. The focus is imposed on the impacts of different reaction conditions (water-to-solid ratios and pressures of CO2). Based on the FT-IR, XRD and ESEM-EDS analysis, CO2 is transformed into carbonates of five vibrational models after mineralization and largely sequestered as calcite by portlandite, which forms a passivated layer on the FA surface. The particle size of carbonated FA particles gets smaller and less uniform, and the variation laws of the particle size at full scale are analyzed by particle size intervals. The variation process of the pore can be divided into the dissolution of FA for pore expansion, the low degree of CO2 mineralization reaction for further expanding the pore and the high reaction degree for pore shrinkage. This paper provides theoretical bases for improving the direct CO2 sequestration capacity and research directions for the subsequent application properties of carbon sequestration products.

Characteristics of ash formed by different lubricant additives and its effect on DPF performance

Diesel Particulate Filter (DPF) is an important technology to reduce diesel exhaust particles. The ash formed by the combustion of lubricant oil will be deposited in the DPF, which will affect the filtration efficiency of DPF. In this paper, the ash generated in the burner by combustion of two lubricant additives mixed with diesel fuel were obtained by the burner test of ash rapid loading. The microscopic morphology of ash was studied by scanning electron microscopy and the fractal dimension was calculated based on fractal theory. Chemical composition analysis was performed using energy-dispersive X-ray spectroscopy. The filtration efficiency of DPF was tested with EEPS 3090 when loaded with different ash fractions. The results show that the average fractal dimension of Mg-based ash (1.5791) is higher than that of Ca ash (1.5420), indicating a more detailed surface structure at the microscopic level. This suggests that Mg-based ash is more likely to plug, sinter and even form bridging phenomenon in the DPF inlet channel. The filtration efficiency of DPF increases and then decreases with the loading of ash. The capture efficiency of large particles of 40–200 nm is increasing with the loading of Ca-based ash. However, due to the higher fractal dimension, the loading of Mg-based ash can significantly improve the capture efficiency of small particles of about 10 nm. This work is beneficial to explain the influence of ash on the efficiency of DPF in filtering particles of different sizes.

Research on leakage environmental risk assessment and risk prevention and control measures in the long-term landfill process of ultra-alkaline fly ash

In this study, we simulated the actual landfill disposal process using accelerated carbonization experiments, based on the leaching characteristics of heavy metals from “alkaline” fly ash, and used the LandSim–HELP coupling model to assess the environmental risk of the leaching. The results showed that the leaching data of “alkaline” fly ash before carbonization showed the illusion of admission to landfill with only a small amount of chemical addition or even without curing/stabilization. The leached concentrations of Zn and Cd from “alkaline” fly ash after carbonation were significantly higher. The risk assessment of the leakage of heavy metals in the case of a single artificial composite liner system showed that the exposure concentrations of Pb, Zn, and Cd in samples exceeded Standard for groundwater quality (GB/T 14848–2017) the Class III permissible limits after carbonation; exposure risk for Cd was exceeded in all samples. However, although the use of a double-layer artificial composite liner to improve the level of impermeability effectively reduced the risk of Cd leaching, so that none of the non-carcinogenic risks exceeded the standard, the carcinogenic risk of Cd in the carbonized samples exceeded the factor of 1.1–4.5 of the acceptable hazard quotient, and the contamination characteristics of the alkaline fly ash still need to be kept in view.

Study on semi-dynamic leaching and microstructure characteristics of MSWI fly ash solidified sediment

municipal solid waste incineration (MSWI) fly ash partially replaces cement to solidify sediment, and then can be used as intermediate cover materials in landfill as one of the resources utilization ways of MSWI fly ash and sediment. The strength and the semi-dynamic leaching characteristics of MSWI fly ash solidified sediment under hydrochloric acid attack at different pH were studied by means of unconfined compressive strength (UCS), semi-dynamic leaching, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Thermogravimetric analysis (TGA). Results revealed that the UCS strength increased as the curing age and cement content increased. When the curing content is 50% and the replacement ratio of MSWI fly ash is 75% and 80%, the UCS of 7 d can be greater than 50 kPa. The primary contribution to the strength development was from silicic acid gels such as calcium silicate hydrate (C–S–H) and carbonates. Notably, the leaching behavior of Zn and Cu within the solidified sediment underwent substantial alterations. The leaching amount of heavy metals in a strong acidic environment (pH = 2) is significantly greater than that in a weak acidic (pH = 4) and neutral (pH = 7) environment. Conversely, minimal disparities were observed in the leaching characteristics of Zn and Cu between the weakly acidic and neutral environments. Ca(OH)2, C–S–H and carbonate exhibits a remarkable acid-resistant buffering capacity in the solidified sediment. The obvious diffusion coefficient (Dobs) was less than 10−9 m2/s in semi-dynamic leaching tests. Moreover, the mobility of Zn and Cu surpassing 12.5, coupled with a leaching index exceeding 8, further attests to the favorable S/S outcome achieved. Based on these findings, the solidified material is confidently recommended to be used as suitable landfill middle soil cover material.

Characteristics of Fly Ash as a Constituent Material for Geopolymer

Fly ash waste from the Asam-Asam Power Plant in South Kalimantan continues to increase. Various attempts have been made to utilize fly ash waste, among others. as a basic material for making geopolymers. Geopolymer is environmentally friendly because it replaces all cement with high Silica (Si) and Alumina (Al) wastes such as fly ash. This study aims to characterize fly ash as a raw material of geopolymer. Fly ash was filtered using 200 mesh and then heated in an oven at 105°C for 24 hours. The prepared fly ash was then tested for physical properties and compound analysis using XRF, identification of chemical bonds and functional groups using FTIR, morphology, and elements using SEM EDX. Initial and final setting time was investigated using the Vicat apparatus to determine e whether cement is undergoing proper hydration. The results indicated that the fly ash was classified to class F. That was based on the amount of SiO2 + Al2O3 + Fe2O3 of 85.91%, and the CaO content was less than 10%. Moreover, fly ash’s initial and final setting time was 1072.5 and 3180 minutes, respectively. Fly ash in this research can be used as a raw material for geopolymers.

Characterization of Nanocomposite Mixture Polyvinyl Alcohol and Rice Husk Ash

Characterization of Nanocomposite Mixture Polyvinyl Alcohol and Rice Husk Ash

Carbon Sequestration by Soils of Ash Dump Forest Areas in the Middle Urals (Russia)

The purpose of this article was to assess the participation of young soils of ash dump forest communities in carbon sequestration by soils of southern taiga forests, considering the physico-chemical properties of the ash substrate and forest litter (pH, TOC, TN, content of P and K mobile compounds, and exchangeable Ca and Mg ions). It was revealed that on three Middle Ural ash dumps (composed of fly ash from various brown coals) over 50–60 years, forest communities spontaneously formed according to the zonal type (with the dominance of Betula pendula Roth and Populus tremula L.) with poorly differentiated young soils—technosols. For the first time, as a result of using an integrated approach to assess the direction of forest ecosystem formation on fly ash dumps, a tendency to increase carbon stocks in technogenic soils that have not reached the level of zonal soils was revealed, as well as the dependence of C accumulation on some physico-chemical characteristics of ash was established. Carbon stocks in Technosols are on average equal to 44 t/ha but vary significantly. It was shown that there is a medium negative relationship between the content and stocks of organic carbon in soils formed on a technogenic substrate and the content of mobile phosphorus compounds in them (the correlation coefficient is −0.58 and −0.53, respectively). The average carbon stocks in the litter of technosols, which is the main source of organic carbon in forest soils, are 3.2 t/ha. It was revealed that the carbon stocks in the litter are most influenced by the content of exchangeable calcium cations and magnesium in it (the correlation coefficients are −0.68 and −0.69, respectively). Any correlation between the studied litter parameters and carbon accumulation in the soils of ash dumps was found. The study revealed that the carbon stocks in the technosols of ash dump forest communities are two times less than the carbon stocks in the zonal forest soils of the Middle Ural southern taiga. The stocks of this element in the litter of young soils are equal to 1/3 of the litter of zonal soils. The composition of the humus substance system formed in the soils of forest areas of ash dumps and zonal soils is similar. The results of this study can serve to fill gaps in the knowledge about carbon sequestration by soils and aim to draw attention to forest communities of technogenic ecosystems to consider the contribution of their components to carbon sequestration.

Assessment of the Slagging Tendency in Power Plant Boiler Furnaces Depending on the Physical-Chemical Characteristics of Ash and Coal

The purpose of the work is to select replacing design coal possible options for low slagging potential reasons in the furnace and on adjacent heating surfaces. Solved problems: the main slagging indices (SI) are summarized, based on considering the two main parameters of the formation of ash deposits, namely viscosity and fusibility. An analysis of existing methods for assessing slagging processes of heating surfaces in steam power boilers was carried out. The scientific goal is achieved by the proposed method of ranking coals according to their slagging tendency on power boiler heating surfaces based on their physicochemical properties. The methodology is based on the slagging potential dependence of the fusibility and viscosity ash characteristics, considering the ratio of the ash percentage content to the heating value of coal. The most important result is ranking of 28 coals of various grades (subbituminous, bituminous, anthracite) burned at Russian power plants according to their tendency to form ash deposits on the furnaces of power boilers. The significance of the results obtained lies in the identification of two coal deposits, subbituminous Irsha-Borodinsky and Berezovsky in Easten Siberia and Kuznetsky bituminous in Western Siberia, which are universal during the transition to burning non-design fuel from the slagging potential point of view. The dependences of the change in ash viscosity and SI on the 2 2 3 / SiO Al O and 2 3 2 / Fe O SiO ratios in ash for Irsha-Borodinsky and Moscow region coals were under consideration. It was concluded that the value of the SI is directly proportional to the load ash content r A and could differ more by an order of magnitude for different coal.

Study on the co-combustion behavior of semi-coke and typical biomass: Combustion, NO emission and ash characteristics analysis

In order to realize the integrated utilization of semi-coke (SC) and biomass, the co-combustion behavior of SC and three typical biomass (corn stalk (CS), rice stalk (RS) and pine wood (PW)) was experimentally studied in terms of combustion, NO emission and ash characteristics. The results of thermogravimetric (TG) analysis show that the positive interactions between SC and biomass mainly occur at the later combustion stage of blends, leading to the combustion of SC in advance. Based on the ignition and comprehensive combustion indexes, the optimal blending ratios of CS and RS are considered as 20%. The co-combustion experiments conducted at the biomass blending ratio of ≤40% in an electrical-heated fluidized bed rig also prove that the combustion performance of SC can be improved by biomass, and the NO emission decreases with the biomass blending ratio. The ash deposition problem should be paid attention when more than 20% CS or RS is blended, which is related to the alkali aluminosilicates and K3Na(SO4)2 in the fly ash of SC/CS and SC/RS blends, respectively. Meanwhile, the effect of PW in this regard is limited due to its extreme low ash content. In summary, the blending ratio for CS and RS is suggested as 20% when co-combusting with SC, while the appropriate PW blending ratio is 40%. The achievements of this study are conducive to the clean and high-efficiency utilization of semi-coke and CO2 emission reduction.

Experimental Investigation and Numerical Model for Chloride Diffusivity of Long-Age Fly Ash Cement Slurry

Fly ash is a by-product of coal-fired thermal power plants and offers great potential for the use of resources. To effectively improve the durability of reinforced concrete structures in marine environment and achieve waste to treasure, fly ash is widely used as a pozzolanic material due to its long-hydration characteristics and effects of micro-aggregate, micro-filling and secondary hydration. In this study, both the experimental investigation and numerical simulation are carried out to study the chloride transport characteristics of fly ash cement paste. The variation in chloride diffusivity with fly ash content, water-to-binder ratio and curing age up to 360 days is studied via accelerated conductivity measurement, and it is found that the above three experimental variables have a significant impact on the chloride diffusivity. For the influence of the dosage of fly ash, the optimum dosage is 30%. By introducing specific rules for the particle distribution, the fresh fly ash cement paste is first made. Based on the volume change characteristics of fly ash and cement particles after hydration, the vector hydration model of fly ash cement paste is established by considering the water shortage effect caused by hydration layer interference. After the accuracy of this hydration model is verified by the results from third-party experiments, the random walk algorithm is proposed to calculate the diffusion coefficient of the reconstructed mineral admixture cement paste. By comprehensive comparison with the experimental results from the third-party and self-conducted experiments, the numerical model for predicting the chloride diffusivity of fly ash cement paste is verified.

Characterization of Coconut Husk Ash as Potential Substitute for Fly Ash in Geopolymer Concrete

Concrete is recognized as the most commonly used man-made material in the world. But because of all the modern developments in the building industry, this leads to compromises that worsen the environment. The third-largest source of anthropogenic CO2 emissions in the world is the cement sector. Alternately, cement-like substances known as geopolymer concrete could be produced from pozzolan material. A form of concrete known as geopolymer concrete uses silica and aluminum-rich geopolymeric elements in place of cement entirely. This new technology is gaining popularity, offering a more environmentally friendly alternative. This study focuses on characterization of coconut husk ash using Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS), and Fourier Transform Infrared (FTIR) Spectroscopy in order to investigate its efficiency as a potential substitute for fly ash in geopolymer concrete.

Physicochemical evaluation of acid whey obtained from doble crema cheese produced in Belén, Boyacá, Colombia

The composition of acid whey makes it less usable, and it is an environmental and technical problem. This research aims to estimate the physicochemical characteristics of the doble crema cheese acid whey, from nine factories in the municipality of Belén in Boyacá. Laboratory methods were validated using the Lactoscan analyzer determinations and comparing them with reference methods. Accuracy was expressed in terms of relative error (% Edet) and f- and p-values; then, correlation curves were elaborated. To perform the physicochemical characterization of whey, fat, Solids-Not-Fat (SNF), protein, lactose, pH, total ash, calcium, density, and acidity were determined. The statistic of the comparison between analysis methods showed low percentages of relative error, there were no significant differences, and they had correlation coefficients greater than 0,8. The results of the physicochemical characterization showed differences in the content of protein, SNF, lactose, fat, ash, calcium, acidity, and pH. Each manufacturer has a manufacturing process for cheese and whey. There were no statistical differences for SNF, density, lactose, fat, ash, and pH within each company. However, there were differences between protein and acidity, even though companies work with the same quality of raw material and processing, there are deficiencies in the coagulation, drainage, and conservation of the whey. The analyzed acid whey is a good source of protein, calcium, lactose and has low fat content, which is attractive for manufacturing food products.

Air and oxy-fuel incineration disposal of invasive biomass water lettuce (Pistia stratiotes L.): performance, kinetics, flue gas emissions, mechanisms, and ash characteristics

Air and oxy-fuel incineration disposal of invasive biomass water lettuce (Pistia stratiotes L.): performance, kinetics, flue gas emissions, mechanisms, and ash characteristics

Effect of Waste Tire Aggregate on Thermal and Strength Characteristics of Fly Ash–Based Geopolymer Composites Produced at Various Binder Contents

Effect of Waste Tire Aggregate on Thermal and Strength Characteristics of Fly Ash–Based Geopolymer Composites Produced at Various Binder Contents

Study on effect of furfural residue addition on fusion characteristics of gasification coal ash

The co-gasification of furfural residue with coal is a feasible way to realize its clean and efficient utilization, but there is a high content of alkaline components in the furfural residue ash. Therefore, the effect of furfural residue addition on the fusion temperature of gasification coal ash was investigated, in which a typical furfural residue and two gasification coals with different ratios of silicon to aluminum (Si/Al) were selected. X-ray diffraction instrument (XRD) was used to measure the mineral evolution of co-gasification ash at different temperatures. The phase change in equilibrium state was calculated by the software FactSage. The results show that with the increase in furfural residue addition ratio, the fusion temperatures of both gasification coal ashes first increase and then decrease, while the increase trend of fusion temperatures for the coal with a high Si/Al ratio is more significant. When the furfural residue is added, the resulting high melting point mineral of gasification slag is changed from anorthite (CaAl2Si2O8) to leucite (KAlSi2O6) that is still present as a solid phase at 1300 °C, resulting in an increase of AFTs. The coal ash with more amount of SiO2 can react with K2O to produce more leucite (KAlSi2O6) with a higher fusion point, thus causing the ash fusion temperatures to rise. However, as the ratio of furfural residue addition continues to increase, the ash fusion temperatures decrease, which is attributed to the formation of kaliophilite (KAlSiO4) with a low fusion point that is generated in the presence of higher content of K2O.

Pengaruh Konsentrasi Pelarut NaOH dan Waktu Aging pada Pembuatan Silika Gel dari Fly Ash Batu Bara

Fly ash has the potential to be used as a raw material in the production of silica gel. This study aims to characterize fly ash and silica gel, determine the effect of NaOH concentration and aging time on the manufacture of silica gel, and determine the trapping power of silica gel. In this research, the production of silica gel begins with the washing of fly ash using HCl. Next, NaOH is added with varying concentrations of 1.5 N, 2.5 N, 3.5 N, and 4.5 N. The formed Na2SiO3 is then mixed with H2SO4 of 3 N concentration, with aging times of 12 hours, 15 hours, and 18 hours. The highest yield of silica gel is 49.61% at a NaOH concentration of 4.5 N and an aging time of 15 hours. The highest water vapor adsorption capacity of the silica gel is 883.00 mg/g at a NaOH concentration of 3.5 N and an aging time of 15 hours. SEM-EDX characterization results indicate a diverse morphology and size for both fly ash and silica gel. The SiO2 content in fly ash is 41.64%, while in silica gel, it is 41.42%. FTIR characterization of fly ash and silica gel reveals the presence of functional groups such as silanol (Si-O), siloxane (Si-O-Si), and hydroxyl (Si-OH) which are active sites in silica gel.