Thermal Behavior of Celsian Ceramics Synthesized from Coal Fly Ash

2012 ◽  
Vol 1373 ◽  
Author(s):  
Jorge López-Cuevas ◽  
David Long-González ◽  
Carlos A. Gutiérrez-Chavarría
Keyword(s):  
Fly Ash ◽  
Thermal Behavior ◽  
Coal Fly Ash ◽  
Thermal Analyses ◽  
Linear Thermal Expansion ◽  
Raw Material ◽  
Synthesis Conditions ◽  
Calcination Step ◽  
Heating Microscopy ◽  
The Mean

ABSTRACTCelsian with a chemical composition of Ba0.75Sr0.25Al2Si2O8, is synthesized by using coal fly ash (byproduct of a Mexican coal-burning power plant, composed mainly by SiO2 and Al2O3) as main raw material. The thermal behavior of the synthesized material is evaluated by differential (DTA) and gravimetric (TGA) thermal analyses as well as by heating microscopy; its coefficient of linear thermal expansion (CTE) is also determined. Heating microscopy shows that cylinders of compacted powdered Celsian start sintering at ∼1140 ºC, which is associated with a considerable contraction occurring up to 1500 ºC. The mean CTE value of the material in the temperature range of 30-1100ºC is slightly affected by the synthesis conditions employed. Synthesis at 1400 or 1300 ºC during 10 h, with a pre-calcination step at 900 ºC/5h in both cases, produce mean CTE values of 5.15 x 10-6 and 5.43 x 10-6 ºC-1, respectively. On the other hand, Celsian synthesized at 1400 ºC/10 h, without the pre-calcination step, has a mean CTE value of 5.25 x 10-6 ºC-1. Lastly, the DTA/TGA analysis of the synthesized material shows that a slight weight gain takes place from room temperature to 1100ºC, which is followed by a slight weight loss up to 1300ºC. This is attributed to oxidation and evaporation of some of the impurities present in the material.

scholarly journals Recovery of Cenospheres and Fine Fraction from Coal Fly Ash by a Novel Dry Separation Method

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3576
Author(s):  
Jan Wrona ◽  
Witold Żukowski ◽  
Dariusz Bradło ◽  
Piotr Czupryński
Keyword(s):  
Fly Ash ◽  
Coal Fly Ash ◽  
Fine Fraction ◽  
Free Fall ◽  
Raw Material ◽  
Fluidised Bed ◽  
Air Chamber ◽  
Pneumatic Separation ◽  
Bed Separation ◽  
Separation Product

Aluminosilicate microspheres are a valuable fraction of coal fly ash with diverse applications due to their low density. Currently, there is no efficient and ecologically rational method of cenosphere recovery from fly ash. A combination of dry methods for the recovery of both fine ash particles and aluminosilicate microspheres from coal fly ash is presented. It is comprised of fluidised bed separation followed by screening and pneumatic separation in a free-fall air chamber. Fluidised bed separation was assisted by a mechanical activator to prevent agglomeration. This step reduced the portion of material that required further treatment by 52–55 wt.%, with the recovery of microspheres exceeding 97%. Then, the concentrates were individually subjected to pneumatic separation. The final separation product for the fly ash containing 0.64 wt.% cenospheres was a cenosphere concentrate that constituted about 17 wt.% of the initial fly ash. The recovery of cenospheres was around 81%. Usage of a combination of dry methods allowed for maintaining almost 83 wt.% of the raw material in its dry form. Furthermore, the produced fly ash grain fractions could be used for different industrial purposes.

scholarly journals Characterization of the Physical, Chemical, and Adsorption Properties of Coal-Fly-Ash–Hydroxyapatite Composites

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 774
Author(s):  
Eleonora Sočo ◽  
Dorota Papciak ◽  
Magdalena M. Michel ◽  
Dariusz Pająk ◽  
Andżelika Domoń ◽  
...  
Keyword(s):  
Fly Ash ◽  
Coal Fly Ash ◽  
Thermal Power ◽  
Synthesis Conditions ◽  
High Calcium ◽  
Ft Ir ◽  
Ir Analysis ◽  
Wet Synthesis

(1) Hydroxyapatite (Hap), which can be obtained by several methods, is known to be a good adsorbent. Coal fly ash (CFA) is a commonly reused byproduct also used in environmental applications as an adsorbent. We sought to answer the following question: Can CFA be included in the method of Hap wet synthesis to produce a composite capable of adsorbing both heavy metals and dyes? (2) High calcium lignite CFA from the thermal power plant in Bełchatów (Poland) was used as the base to prepare CFA–Hap composites. Four types designated CFA–Hap1–4 were synthesized via the wet method of in situ precipitation. The synthesis conditions differed in terms of the calcium reactants used, pH, and temperature. We also investigated the equilibrium adsorption of Cu(II) and rhodamine B (RB) on CFA–Hap1–4. The data were fitted using the Langmuir, Freundlich, and Redlich–Peterson models and validated using R2 and χ2/DoF. Surface changes in CFA–Hap2 following Cu(II) and RB adsorption were assessed using SEM, SE, and FT-IR analysis. (3) The obtained composites contained hydroxyapatite (Ca/P 1.67) and aluminosilicates. The mode of Cu(II) and RB adsorption could be explained by the Redlich–Peterson model. The CFA–Hap2 obtained using CFA, Ca(NO3)2, and (NH4)2HPO4 at RT and pH 11 exhibited the highest maximal adsorption capacity: 73.6 mg Cu/g and 87.0 mg RB/g. (4) The clear advantage of chemisorption over physisorption was indicated by the Cu(II)–CFA–Hap system. The RB molecules present in the form of uncharged lactone were favorably adsorbed even on strongly deprotonated CFA–Hap surfaces.

Modeling the thermal behavior of coal fly ash based polymer gel system for water reduction in oil and gas wells

2017 ◽  
Vol 157 ◽  
pp. 430-440 ◽  
Author(s):  
Ahmad A. Adewunmi ◽  
Suzylawati Ismail ◽  
Taoreed O. Owolabi ◽  
Abdullah S. Sultan ◽  
Sunday O. Olatunji ◽  
...  
Keyword(s):  
Fly Ash ◽  
Thermal Behavior ◽  
Oil And Gas ◽  
Coal Fly Ash ◽  
Polymer Gel ◽  
Gas Wells ◽  
Water Reduction ◽  
Oil And Gas Wells ◽  
Gel System

Utilization of Fly Ash in the Synthesis of Refractory Forsterite-Spinel Ceramics

2021 ◽  
Vol 321 ◽  
pp. 131-140
Author(s):  
Martin Nguyen ◽  
Radomír Sokolař
Keyword(s):  
Thermal Expansion ◽  
Fly Ash ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Power Plants ◽  
Linear Thermal Expansion ◽  
Aluminium Oxide ◽  
Raw Material ◽  
Modulus Of Rupture ◽  
Shock Resistance

Forsterite refractory ceramics is utilized in the metallurgical and cement industries as a lining of metallurgical furnaces and rotary kilns for its high refractoriness up to 1850°C and refractoriness under load above 1600°C. Another significant property of forsterite is its coefficient of linear thermal expansion utilized in the electrotechnical industry for ceramic-metal joints. Addition of aluminium oxide into the raw material mixture results in creation of magnesium-alumina spinel (MgO·Al2O3) which improves sintering, thermal shock resistance and mechanical properties in comparison with pure forsterite ceramics. Inexpensive source of aluminium oxide is fly ash. Utilization of fly ash, secondary energetic product of coal-burning power plants, is important for the environment and sustainable development. This paper evaluated properties of fly ash-based forsterite-spinel ceramics in comparison with alumina-based forsterite-spinel ceramics. Forsterite-spinel ceramics was synthesized from olivine, calcined magnesite and fly ash/alumina powders. XRD analysis was used to determine mineralogical composition, thermal analyses were used to determine the behaviour during firing and scanning electron microscopy to determine the morphology of crystal phases. Refractoriness of pyrometric cones, refractoriness under load, thermal shock resistance, coefficient of linear thermal expansion, water absorption, porosity and modulus of rupture were also determined on fired test samples.

scholarly journals Acetone-Sensitive Thin Films Comprising Coal Fly Ash Na-X Zeolites and Sol–Gel Nb2O5 Matrix

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2399
Author(s):  
Katerina Lazarova ◽  
Silviya Boycheva ◽  
Marina Vasileva ◽  
Denitza Zgureva-Filipova ◽  
Biliana Georgieva ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Fly Ash ◽  
Coal Fly Ash ◽  
Sol Gel ◽  
Optical Quality ◽  
Film Deposition ◽  
Reflectance Spectra ◽  
Raw Material ◽  
X Zeolites

In this study, thin composite films of a sol–gel Nb2O5 matrix doped with coal fly ash Na-X zeolites were deposited by the spin-coating method. Fly ash of lignite coal collected from the electrostatic precipitators of one of the biggest TPPs in Bulgaria was used as a raw material for obtaining zeolites. Zeolite Na-X was synthesized by ultrasonic-assisted double stage fusion-hydrothermal alkaline conversion of coal fly ash. In order to improve the optical quality and sensing properties of the deposited thin films, synthesized zeolites were wet-milled for 60, 120, and 540 s prior to film deposition. The surface morphology of zeolite powders was studied both by scanning electron microscopy and transmission electron microscopy, while their porosity was investigated by N2-physisorption. Refractive index, extinction coefficient, and thickness of the films were determined through fitting of their reflectance spectra. The sensing ability of thin films towards acetone vapors was tested by measuring the reflectance spectra prior to and during exposure to the analyte, and the change in the reflection coefficient ∆R of the films was calculated. The influence of milling time of zeolites on the sensing and optical properties of the films was assumed and confirmed.

scholarly journals Studies on the CO2 Capture by Coal Fly Ash Zeolites: Process Design and Simulation

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8279
Author(s):  
Silviya Boycheva ◽  
Ivan Marinov ◽  
Denitza Zgureva-Filipova
Keyword(s):  
Fly Ash ◽  
Co2 Capture ◽  
Carbon Capture ◽  
Low Cost ◽  
Coal Fly Ash ◽  
Cost Effective ◽  
Thermal Recovery ◽  
Raw Material ◽  
Dynamic Adsorption ◽  
Co2 Capture Capacity

At present, mitigating carbon emissions from energy production and industrial processes is more relevant than ever to limit climate change. The widespread implementation of carbon capture technologies requires the development of cost-effective and selective adsorbents with high CO2 capture capacity and low thermal recovery. Coal fly ash has been extensively studied as a raw material for the synthesis of low-cost zeolite-like adsorbents for CO2 capture. Laboratory tests for CO2 adsorption onto coal fly ash zeolites (CFAZ) reveal promising results, but detailed computational studies are required to clarify the applicability of these materials as CO2 adsorbents on a pilot and industrial scale. The present study provides results for the validation of a simulation model for the design of adsorption columns for CO2 capture on CFAZ based on the experimental equilibrium and dynamic adsorption on a laboratory scale. The simulations were performed using ProSim DAC dynamic adsorption software to study mass transfer and energy balance in the thermal swing adsorption mode and in the most widely operated adsorption unit configuration.

Effect of Mechanical Activation on the Synthesis of Ba-Celsian and Sr-Celsian using Precursor Mixtures Containing Coal Fly Ash

2016 ◽  
Vol 1812 ◽  
pp. 89-94
Author(s):  
Claudia M. Lopez-Badillo ◽  
Jorge López-Cuevas ◽  
Carlos A. Gutiérrez-Chavarría ◽  
José L. Rodríguez-Galicia ◽  
Elia M. Múzquiz-Ramos
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Solid State ◽  
Mechanical Activation ◽  
Solid State Reaction ◽  
Milling Time ◽  
Coal Fly Ash ◽  
Raw Material ◽  
Attrition Mill ◽  
Sintered Materials

ABSTRACTBaAl2Si2O8 and SrAl2Si2O8 were synthesized by solid-state reaction of stoichiometric mixtures of either BaCO3 or SrCO3 with coal fly ash and Al2O3. The mixtures were mechanically activated in an attrition mill for up to 12 h and then reaction-sintered at 900-1300 °C, aiming to promote the formation of BaAl2Si2O8 and SrAl2Si2O8 as well as the conversion from their hexagonal (Hexacelsian) into their monoclinic (Celsian) forms, which is associated with improved mechanical properties in the sintered materials. Especially in the case of SrAl2Si2O8, the formation of Celsian was favored at relatively low sintering temperatures by increasing milling time. Although only the SrAl2Si2O8 composition was fully converted into Celsian, the Hexacelsian to Celsian conversions obtained for the mechanically-activated BaAl2Si2O8 composition were significantly higher than those previously reported in the literature for this compound. This could be attributed to the use of coal fly ash as raw material, which contains mineralizers that promote the mentioned conversion.

scholarly journals Magnetite concentrate from coal fly ash of Kashirskaya GRES- the raw material for the production of metal products by reduction smelting

2021 ◽  
Vol 1942 (1) ◽  
pp. 012048
Author(s):  
D V Zinoveev ◽  
L M Delicyn ◽  
Y V Ryabov ◽  
R V Kulumbegov ◽  
A S Zakunov ◽  
...  
Keyword(s):  
Fly Ash ◽  
Coal Fly Ash ◽  
Raw Material ◽  
Magnetite Concentrate ◽  
Reduction Smelting ◽  
Metal Products

Synthesis and Characterization of Cordierite, Mullite and Cordierite-Mullite Ceramic Materials using Coal Fly Ash as Raw Material

MRS Advances ◽  
2017 ◽  
Vol 2 (62) ◽  
pp. 3865-3872
Author(s):  
J. López-Cuevas ◽  
E. Interial-Orejón ◽  
C.A. Gutiérrez-Chavarría ◽  
J.C. Rendón-Ángeles
Keyword(s):  
Fly Ash ◽  
Flexural Strength ◽  
Vickers Microhardness ◽  
Coal Fly Ash ◽  
Ceramic Materials ◽  
Raw Material ◽  
X Ray Diffraction ◽  
Mullite Ceramic ◽  
Two Temperatures

AbstractCordierite (Mg2Al4Si5O18), Mullite (Al4+2xSi2-2xO10-x) and Cordierite-Mullite ceramic materials were obtained from a stoichiometric mixture of coal fly ash (CFA) as a source of SiO2 and Al2O3, plus high-purity MgO and Al2O3. The starting stoichiometric mixtures were homogenized, and then uniaxially pressed, cold isostatically pressed, and sintered at 1200-1600 °C for 2-5 h. The sintered materials were characterized by X-ray diffraction, scanning electron microscopy, Vickers microhardness, density and four-point flexural strength. In general, the desired phases tended to form in the composites at temperatures of 1350 or 1400 °C, with a considerable amount of glassy phase developing from 3 h onwards at one of those two temperatures, depending on the composite composition. The microstructure of the composites consisted of a matrix of Cordierite and interwoven needles of Mullite. The bulk density decreased, while the flexural strength and the Vickers microhardness increased with increasing nominal content of Mullite in the composites. A synergistic effect taking place between Cordierite and Mullite enhances the mechanical properties of the composites.

Parameters Affecting the Synthesis of X and A Zeolites from Coal Fly Ash

2021 ◽  
Vol 2 (1) ◽  
pp. 53-59
Author(s):  
A. Korpa ◽  
V. Teneqja ◽  
S. Gjyli ◽  
A. Andoni
Keyword(s):  
Fly Ash ◽  
Industrial Waste ◽  
Acid Treatment ◽  
Coal Fly Ash ◽  
Exchange Capacity ◽  
Raw Material ◽  
Crystallization Time ◽  
Zeolite Synthesis ◽  
Different Types ◽  
Type Zeolite

This paper summarizes the investigation results on the main parameters affecting the synthesis of type X and A zeolites using coal silicious fly ash (FA) as raw material. The synthesis was performed by dissolution of alkali-fused alumino-silicates, followed by hydrothermal treatment. The experimental data confirm that fly ash SiO2/Al2O3 ratio, NaOH/FA ratio, acid treatment of pre-fused fly ash, salinity of solution have a significant effect on type and properties of newly formed zeolites. In summary, the results show that A and X-type zeolite form with FA SiO2/Al2O3 ratio < 1.12 and > 1.86, respectively. Moreover, FA characterized by SiO2/Al2O3 mole ratio of 3.15 is suitable for X-type zeolite synthesis while A-type zeolite does not form without NaAlO2 addition. The crystallization occurs faster at higher temperatures although above 90°C X-type zeolite evolves into more stable phases whereas increasing the crystallization time from 1 to 72 hours, the yield of the synthetic products enhances from 60 to 75%. The use of seawater is responsible for the synthesis of X-type showing both lower purity and specific surface area. However, the synthetic products are characterized by high exchange capacity (> 320 meq/100 g), thus suggesting their successful application as adsorbents and catalysts in different types of wastewater and industrial waste treatments.

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