Chemical Composition Of Fly Ash Research Articles

The properties of fly ash derived lightweight aggregates obtained using microwave radiation

This study evaluates the impact of a fly ash chemical composition, beidellitic clay addition and microwave heating time on the properties of lightweight aggregates. F class fly ash and fly ash with high carbon content (38%) were used. A waste solution after zeolite synthesis was used as an agglomerating agent. The analyzes showed differences in the chemical composition, mineral composition, microstructure as well as in physical and mechanical properties of produced aggregates. The presence of carbon in high-carbon fly ash caused an increase in the porosity of aggregates which resulted in lower dry particle density (1.92–2.35 g/cm3), apparent particle density (0.63–0.95 g/cm3), and higher water absorption (12–18%), and lower compressive strength in comparison to the aggregates obtained on the basis of class F fly ash. Longer microwave heating time resulted in higher compressive strength.

The Effect of Different Crumb Rubber Loading on the Properties of Fly Ash-Based Geopolymer Concrete

This study aims at viability study the effects of addition of crumb rubber loading in fly ash-based geopolymer concrete for its properties. Crumb rubber is the recycled rubber from automotive scrap tires which can reduce scrap into uniform granules shapes that can absorb stress that reduces the reflective cracking because of its elastic properties. Geopolymer concrete includes an alternate material i.e Fly ash in replacement of cement, as a binding material. Mortar cubes of size 50mm x 50mm x 50mm were casted and curing at room temperature. X-Ray Fluorescence (XRF) and Scanning Electron Microscopy (SEM) were used to analyze the chemical composition of fly ash and the microstructure of the concrete. Moreover, compressive strength, water absorption capacity, and density of concrete are interrelated. Compression test, water absorption capacity test and density test were performed in hardened state, for different proportions of replacing the aggregate with crumb rubber i.e. 5%, 10%, 15%, 20%. Compressive strength test was performed at 7, 14 and 28 days. Results were obtained and compared. Decrease in strength was observed at 7, 14 and 28 days.

Investigation of thermal radiation of furnace gases generated from solid-fuel combustion in a steam boiler

The article presents a methodology of comprehensive study of thermal radiation emitted by furnace gases during solid fuel combustion. The characteristics of initial fuel and chemical composition of flyash are described. The absorption coefficients of the gaseous phase in relation to the wavelength, temperature, and concentration of the main gas components are measured. The gas composition was determined by calculation of the total combustion products, as well as experimentally (through a gas analyzer). The experimental results on the particle shapes and sizes, the distribution function of flyash particles, the fusibility of mineral part were used to calculate the radiation characteristics of the condensed phase. Calculations of emission characteristics of furnace gases (spectral and integral flux densities and emissivity factors) depending on the influence of each phase at different operating temperatures are presented. The method efficiency is estimated through comparing with calculated and experimental data on the emission characteristics for homogeneous and heterogeneous combustion products. Spectral ranges were chosen to determine the temperature for furnace gases, a plume, and the surface of flyash deposits on the furnace walls. Experimental dependences of the emissivity factors for flyash deposits on temperature are presented. The findings can be used to calculate heat fluxes, for the purposes of furnace gases pyrometry, and to determine the temperature level in the compilation of operational maps for the boiler.

Effects of chemical composition of fly ash on compressive strength of fly ash cement mortar

The effect of the chemical composition of the amorphous and crystalline phases of fly ash on the compressive strength of fly ash cement mortar was studied. The fly ash cement mortars were made by replacing 25 wt% of cement with 16 types of fly ashes, and the specimen’s compressive strengths were evaluated. The compressive strength increased with the mortar’s age due to differences in pozzolanic reactivity. The effects of various chemical parameters of the fly ash were analyzed. The pozzolanic reaction of fly ash was significantly affected by SiO2, Al2O3, and Fe2O3 components, which form the framework of the glass phase, and CaO, MgO, Na2O, and K2O components, which depolymerize the glass structure.

Experimental study of effect additional water on high performance geopolymer concrete

The Earth Summit 1997 in Kyoto (Japan), industrialized countries agreed to reduce gas emissions by 21% to avoid global warming due to greenhouse effect with the release of CO2 into the air. From the research result, cement industry sector all over the world contributes about 8 - 10% of total CO2 emission. This number is quite high and if there is not a special action to reduce, CO2 emissions will continue to increase along with the rapid development of infrastructure in various parts of the world including in Indonesia. To support greenhouse effect reduction efforts due to CO2 emissions and environmental conservation, civil engineers in the world are taking steps to achieve Sustainable Concrete Technology, in order to create “Green Concrete”. For that reason in the direction of “Green Concrete”, innovation is needed to reduce or replace cement in the concrete mixing. The ash waste electrical power generating plants of fly ash is a material containing many SiO2 and Al2O3 which can be used to replace the overall of cement in concrete. Geopolymer concrete is a fly ash-based concrete that replaces the entire cement in its manufacture. Workability in mixing geopolymer concrete is very low, due to the rapid reaction of the alkaline solution when it reacts with fly ash. To improve the workability can be added water at the time of mixing. The fly ash used in the mixing from the Paiton power plant in East Java with grain size 12.06 μm with round granules and chemical composition of fly ash containing SiO2, Al2O3 and Fe2O3 with a total of 75.151%. The planned compressive strength of the concrete is 45 MPa, with a variation of 8M, 12M and 16M NaOH molarity and the ratio of NaOH and Na2SiO3 is 1. Addition of water in concrete mixing with variations of 15, 17.5, 20, 22.5 and 25 liters / m3. The results of this study indicate that the more addition of water in the manufacture of geopolymer concrete can also increase the value of slump, but the excessive addition of water will result in a decrease in the compressive strength of the concrete caused by a decrease in the concentration of the alkaline solution. High molarity values will require additional water to reach the same slump value compared to lower NaOH molarity. With the same mix design, the optimal compressive strength at 8M NaOH was 48.18 MPa with 17.5 liters/m3 of water added with a slump of 12 cm, for 12M NaOH the optimal compressive strength was 51.65 MPa with the addition of 20 liter/m3 with 10 cm slump, while for 16M NaOH the optimum compressive strength is 59.70 MPa with 22.5 liters/m3 of water added with a 5 cm slump. The higher the NaOH molarity will result in a higher compressive strength value and geopolymer concrete compressive strength at early age is higher than conventional concrete.

Material properties, processing & characterization of fly ash based geopolymer

Abstract A Geopolymer is a new generation material widely used in construction industry. It is the sustainable one in which the waste materials produced from thermal power stations are used as partial or complete replacement of cement to make the environment free from the release of carbon dioxide emission from cement manufacturing companies. The paper deals with the study of material properties, processing & characterization of fly ash based Geopolymer. The paper widely describes about the characterization & chemical composition of fly ash based Geopolymers at ambient temperatures. Tests include X-Ray diffraction (XRD), Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS) and physical, mechanical properties include workability, compressive strength tests respectively. Tests result exhibited the potential benefit of fly ash based Geopolymer as an alternative for ordinary Portland cement for the concrete industry.

PENGELOLAAN LINGKUNGAN DENGAN CARA MEMANFAATKAN FLY ASH BATUBARA SEBAGAI BAHAN BAKU MEMBRAN SILIKA DALAM UPAYA MEMINIMALISIR LIMBAH B3 DI PT SEMEN BATURAJA OKU

The target of community service assignments in 2018 is productive communities that need development in the field of environmental management, namely employees of the Quality Control Laboratory of PT. Semen Baturaja OKU. Coal ash is a waste unlike gas from combustion, because it is a solid material that is not easily dissolved and is not volatile so it will be more troublesome in handling. If the amount is large and is not handled properly, then the coal ash can pollute the environment especially caused by fly ash and can be sucked by humans and animals can also affect the condition of the surrounding water and soil so that it can kill the plants. The chemical composition of Fly ash is silica, alumina and iron with little calcium, magnesium, sulfate, and other components. Currently coal fly ash is used in cement plants as a mixture of concrete makers. Because of the smoothness and round shape of the granules, the use of fly ash on the concrete mixture can increase the slack on the concrete mixture. The advantages of using fly ash include increasing the strength of concrete, filling the pores in the concrete so that the porosity of the concrete becomes low, while increasing the density of concrete so that it can increase the tightness of concrete to water. The coal fly ash waste that accumulates also occurs in the industry of PT Semen Baturaja Ogan Komering Ulu. PT. Semen Baturaja is one of the largest cement industries in Sumatra that produces PCC (Portland Composite Cement). PCC type cement is cement made by utilizing inorganic additives such as fly ash and trass. Aside from being an additional material for cement, fly ash can also be used as a raw material for making silica membranes which serves to reduce metal content in acid mine drainage. So that the author wishes to socialize the employees and employees of PT Semen Baturaja especially in the BTA II Quality Control laboratory division to disseminate knowledge about the benefits of coal fly ash as raw material for silica membranes in minimizing B3 waste so that environmental management with a friendly environment will achieved.

Effect of thermal processing on the structural characteristics of fly ashes

This work investigated the course of fly ash’s glassy phase crystallization in terms of structural and thermal changes. On the basis of XRD studies the olivine and albite phases are formed after the second step of the heat treatment. XRD/Rietveld analysis confirmed increased amount of mullite. The occurrence of crystallizing phases depends on the chemical composition of fly ash. It was observed that under the heat treatment of fly ashes with a small amount of modifying oxides a larger mullite superstructure appeared, what favors the albite rich plagioclases formation. The structural changes upon the heat treatment of fly ashes were studied by means of 27Al MAS NMR and FTIR spectroscopy. On the basis of NMR studies it has been confirmed that aluminum ions in devitrified glassy phase occurred only in the tetrahedral positions.

Kinetics of thermal decomposition of PVC/fly ash composites

ABSTRACTIn this study, the kinetics and mechanisms of thermal degradation of Poly Vinyl Chloride (PVC) composites reinforced with class-F fly ash are studied experimentally and numerically using Flynn–Wall model. The addition of fly ash to the polymer matrix results in a decrease in the primary degradation temperature and an increase in the secondary degradation temperature. The metal oxides in the fly ash act as acid absorbers, which results in the destabilization of PVC during its dehydrochlorination process. However, they also react with the chlorine free radicals, which prevents the formation of HCl during degradation. In addition, it is observed that calcium and iron oxides, present in fly ash, are more reactive to the chlorine radicals rather than the silicon and aluminum oxides. The effect of fly ash chemical composition on the degradation of PVC composites was studied by comparing the thermal properties of composites containing two different classes of fly ashes, class-F and class-C, at similar levels. Thermal stability of the composites is found to be dependent on the chemical composition of fly ash. Higher dehydrochlorination rate is observed in the case of composites filled with class-F fly ash than those reinforced with class-C fly ash.

Study on The Geopolymer Concrete Properties Reinforced with Hooked Steel Fiber

In this research, Class F fly ash and a mixture of alkaline activators and different amount of hooked steel fiber were used for preparing geopolymer concrete. In order to analyses the effect of hooked steel fiber on the geopolymer concrete, the analysis such as chemical composition of fly ash, workability of fresh geopolymer, water absorption, density, compressive strength of hardened geopolymer concrete have been carried out. Mixtures were prepared with fly ash to alkaline liquid ratio of 2.0 with hooked steel fibers were added to the mix with different amounts which are 1%, 3%, 5% and 7% by the weight of the concrete. Experimental results showed that the compressive strength of geopolymer concrete increases as the hooked steel fibers increases. The optimum compressive strength obtained was up to 87.83 MPa on the 14th day. The density of geopolymer concrete are in the range between 2466 kg/m3 to 2501 kg/m3. In addition, the workability value of geopolymer without hooked steel fibers is 100 mm while the workability value of geopolymer with hooked steel fibers are between 60 mm to 30 mm.

The use of fractionated fly ash of thermal power plants as binder for production of briquettes of coke breeze and dust

In this paper, we propose to use the slag and ash material of thermal power plants (TPP) operating on pulverized coal fuel. The elemental and chemical composition of fly ash of five Kuzbass thermal power plants differs insignificantly from the composition of the mineral part of coking coal because coke production uses a charge, whose composition defines the main task: obtaining coke with the required parameters for production of iron and steel. These indicators are as follows: CRI reactivity and strength of the coke residue after reaction with CO2 – CSR. The chemical composition of fly ash of thermal power plants and microsilica with bulk density of 0.3-0.6 t/m3 generated at production of ferroalloys was compared. Fly ash and microsilica are the valuable raw material for production of mineral binder in manufacturing coke breeze briquettes (fraction of 2-10 mm) and dust (0-200 μm), generated in large quantities during coking (up to 40wt%). It is shown that this binder is necessary for production of smokeless briquettes with low reactivity, high strength and cost, demanded for production of cupola iron and melting the silicate materials, basaltic rocks in low-shaft furnaces. It is determined that microsilica contains up to 90% of silicon oxide, and fly ash contains up to 60% of silicon oxide and aluminum oxide of up to 20%. On average, the rest of fly ash composition consists of basic oxides. According to calculation by the VUKHIN formula, the basicity index of briquette changes significantly, when fly ash is introduced into briquette raw material component as a binder. The technology of coke briquette production on the basis of the non-magnetic fraction of TPP fly ash in the ratio from 3.5:1 to 4.5:1 (coke breeze : coke dust) with the addition of the binder component to 10% is proposed. The produced briquettes meet the requirements by CRI and require further study on CSR requirements.

Coal combustion emission and ash formation characteristics at high oxygen concentration in a 1 MWth pilot-scale oxy-fuel circulating fluidized bed

Combustion experiments for one common Chinese bituminous coal (Datong) were conducted in air and in O2/dry recycle flue gas (RFG) mixtures with input O2 concentrations of 30%, 40% and 50% in a 1MWth pilot-scale oxy-fuel circulating fluidized bed (CFB). The effect of combustion atmosphere and O2 concentration were investigated to determine their impact on coal combustion efficiency, gaseous pollutant emissions, limestone desulfurization efficiency and chemical composition of the fly ash. The experimental results showed that the unburned char content in fly ash for the 30% O2/RFG combustion mode is slightly higher than that obtained for the air combustion mode. However, when the O2 concentration reaches and exceeds 40%, the content of unburned char in fly ash is less than that obtained under the air firing mode. Compared with the air firing mode, the SO2 emissions under O2/RFG modes are notably higher, and the limestone desulfurization efficiency is lower. Under O2/RFG modes, the NO emissions are much lower, but the N2O emissions are higher than that under the air firing mode, with the level of N2O emission being nearly the same as the corresponding NO emission. There are no obvious differences in the chemical composition of fly ash under air and O2/RFG modes, except for a slightly lower percentage of K2O, Na2O and SO3 under O2/RFG modes at higher O2 concentrations.

Influence of Gypsum Additive on the Formation of Tobermorite in Autoclaved Aerated Concrete

The quality of the aerated concrete strongly depends on the chemical composition of the raw materials, as well as the process of the hydrothermal reaction during autoclaving. Due to the variable chemical composition of fly ashes, it is necessary to identify the effect of each ion on the formation of the microstructure of aerated concrete. This paper examines the process of formation of tobermorite with the addition of sulphates in various percentage representation. The microstructure of aerated concrete is assessed using SEM images and the mineralogical by means of X-ray analysis.

Effect of fly ash chemical composition on the reinforcement corrosion, thermal diffusion and strength of blended cement concretes

This paper presents the results of an experimental study conducted to evaluate the influence of fly ash chemical composition on the physico-mechanical properties and the resistance of reinforced concrete against chloride penetration. The study examines cementitious composites prepared with two different types of fly ash, used at 5% w/w and 10% w/w as cement replacement, and compares them against reference specimens prepared without fly ash. Electrochemical (Half-cell potential, corrosion current) and mass loss of reinforcement steel measurements were performed, while the porosity, compressive/tensile strength and modulus of elasticity were measured to evaluate the quality of concrete; XRD patterns and SEM images coupled with EDX analysis were further recorded and used for mineral identification and microstructure observation respectively. The thermal properties of concrete samples were also estimated. Prior to testing, all specimens were partially immersed in 3.5% w/w NaCl solution. The experimental results indicate that the performance of hardened fly ash concrete depends not only on the CaO and SiO2 content of the additive, but also on its fineness, free lime and sulfate ions content. In particular, the durability properties of concrete containing fly ash with high SO3 and CaOf contents are improved, while concrete containing fly ash with significant amounts of clay minerals exhibits low chloride penetration resistance and strength; additionally, the composite concretes demonstrate low values of thermal diffusion comparing with the OPC concrete.

Comparative Study on Synergetic Degradation of a Reactive Dye Using Different Types of Fly Ash in Combined Adsorption and Photocatalysis

A comprehensive study was carried out on four different fly ashes used as a catalyst for the degradation of Acid Red 1 using ultraviolet rays. These fly ashes are collected from different thermal power stations located at various places in India and having different chemical compositions. Three fly ashes are from lignite-based thermal power plants, and one is from the coal-based power plant. One fly ash is classified as Class F, two fly ashes are classified as Class C and remaining one is not conforming to ASTM C618 classification. X-Ray Fluorescence analysis was used to identify the chemical composition of fly ashes and SiO2, Al2O3, CaO, Fe2O3 and TiO2 were found to be the major elements present in different proportions. Various analysis were carried out on all the fly ashes like Scanning Electron Microscopy to identify the microphysical properties, Energy Dispersive X-Ray spectroscopy to quantify the elements present in the catalyst and X-Ray Diffraction to identify the catalyst phase analysis. The radical generated during the reaction was identified by Electron paramagnetic resonance spectroscopy. The parameters such as initial pH of the dye solution, catalyst dosage and initial dye concentration which influence the dye degradation efficiency were studied and optimised. In 60 min duration, the dye degradation efficiency at optimum parametric values of pH 2.5, initial dye concentration of 10 mg/L and catalyst dosage of 1.0 g/L using various fly ashes, i.e., Salam Power Plant, Barmer Lignite Power Plant, Kutch Lignite Power Plant and Neyveli Lignite Thermal Power plant (NLTP) were found to be 40, 60, 67 and 95 % respectively. The contribution of adsorption alone was 18 % at the above mentioned optimum parametric values. Among the above four fly ash NLTP fly ashes proved to be most efficient.

Characterization of Class F Fly Ash Using STXM: Identifying Intraparticle Heterogeneity at Nanometer Scale

Chemical and physical characterization of fly ash particles were conducted using scanning transmission X-ray microscopy (STXM). Compositional and spatial investigation and correlation among the main elemental constituents of fly ash (Al, Si, and Fe) were conducted based on microscopic and NEXAFS spectral analysis. Homogeneous oxidation and coordination state of Al and Fe were observed whereas Si shows spatial variation in its chemical state. We also identified that Si and Al are spatially correlated at nanometer scale in which high concentration of Si and Al was concurrently and consistently observed within the 30 nm resolution whereas Fe distribution did not show any specific correlation to Al and Si. Results of this study indicate that fly ash chemical composition has heterogeneous distribution depending on the elements which would determine and result in the differences in the reactivity.

Study on Using Chenghe Fly Ash to Prepare 4A Molecular Sieve

In recent years, with the rapid development of coal industry, a large number of coal fly ash has been produced, while the recycling rate of the ash is rather low. It is not only a waste of the precious land resources, but also makes environment suffering severe pollution. As an important kind of new material in the national economy, the demand for molecular sieve is growing. It is possible to synthesis molecular sieve using fly ash. The way is not only energy conservation and environmental protection, but also waste reclamation, according with the theme of the sustainable development.This study is to synthesize the molecular sieve with guide agent by the method of hydrothermal synthesis using Cheng He mining area in Shanxi province, which is on the basis of the analysis of chemical composition of fly ash. It is also to find a approach for the use of fly ash with subtly. Through XRD expert zing phase, SEM observing appearance, the characterizing results show that excellent performance molecular sieve of 4A can be synthesized at conditions: Calcined at 850°C and for 2 hours, then hydrothermal reacted with composition of reaction mixture 3Na2O:1Al2O3:2SiO2: 185H2O at temperature 90°C, crystallization time 6h with 5% guide agent.

Wet-Treated MSWI Fly Ash Used as Supplementary Cementitious Material

Municipal solid waste incineration (MSWI) is a common technique in treatment of domestic waste. This technique annually produces approximately 25 Mt solid residues (i.e., bottom and fly ash) worldwide which is also a major issue in current research. In this research we are concerned with reusing the fly ash (FA) as supplementary cementitious material (SCM) in concrete. Such application solves the problem with heavy metal immobilization as well. To remove the high content of undesired soluble salts, number of washing treatments has been applied. Chemical composition of FA has been examined before and after treatments. The impact of cement substitution by FA in concrete was evaluated by measurement of its compressive strength and durability.

Influence of Pulverized Coal on Characteristics of Fly Ash in SCGP

The chemical composition, microstructure and size distribution of pulverized coal and fly ash samples from SCGP(Shell Coal Gasification Process) devices of four different regions were measured using an energy dispersive spectrometer, a scanning electron microscope, and Coulter particle analyzer. The paper aims to analyze the influence of pulverized coal on characteristics of fly ash. The energy dispersive analysis showed the main elements of chemical composition of fly ash and pulverized coal were C, O, Si, Al, and small amounts of metal elements. The difference of chemical composition of pulverized coal samples illustrates the types of coal were different. The similarity in chemical composition of four types of fly ash was due to the same technical process. Scanning electron microscope measurements showed particulate microstructures of four samples of pulverized coal were irregular, however, particulate microstructures of samples of fly ash were all spherical. The surface of most spherical particles had microspheres that were often agglomerated together. This phenomenon indicated that particulate microstructures of pulverized coal had no influence on particulate microstructures of fly ash. The size distribution showed median size of four pulverized coal samples were 31.59μm, 28.85μm, 25.57μm and 20.62μm. Median size of four fly ash samples were 4.07μm, 3.89μm, 3.45μm and 3.04μm. The particle size of fly ash increases with the growth of particle size of pulverized coal. The crests of particle size distribution curves of pulverized coal were not obvious due to the grinding evenness of coal were low. Particle size distribution curves of fly ash were opposite. This phenomenon indicates that uniform degree of fly ash is not affected by coal grinding evenness. In conclusion, the particle size of pulverized coal is the main influencing factor on the characteristics of fly ash while the influences of type of coal, particulate microstructures and grinding evenness of pulverized coal are not so much. Particle size of fly ash has a vital influence on high-temperature ceramic filters in SCGP. Controlling particle size of pulverized coal has a certain guiding significance to reducing the working load and extending the life of filter elements.

Compressibility of kaolinite treated with fly ash from fluidized bed combustion

Waste products such as fly ash can be an economically advantageous alternative for lime and cement in ground improvement techniques. Current state of knowledge indicates the possibility of using this material successfully in various engineering projects. However, the chemical composition of fly ash is related to the type of coal and combustion technology used in power plant. This fact indicates need for further studies aiming determination the effect of fly ash addition on soil properties. Rate of soil improvement considered in macro level includes designation of treated soil mechanical properties, inter alia compressibility characteristics. Presented results of laboratory tests are a part of a larger experimental work aiming to determine the suitability of fly ash from fluidized bed combustion for the purpose of soil strengthen with the use of selected ground improvement.