scholarly journals Effect of Temperature on Morphology, Phase Transformations and Thermal Expansions of Coal Fly Ash Cenospheres

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 481
Author(s):  
Thye Foo Choo ◽  
Mohamad Amran Mohd Salleh ◽  
Kuan Ying Kok ◽  
Khamirul Amin Matori ◽  
Suraya Abdul Rashid
Keyword(s):  
Differential Scanning Calorimetry ◽  
Fly Ash ◽  
Coal Fly Ash ◽  
Hollow Spheres ◽  
Aluminosilicate Glass ◽  
Effect Of Temperature ◽  
Scanning Calorimetry ◽  
Mullite Phase ◽  
Phase Ordering ◽  
Field Emission Electron Microscopy

Cenospheres are small, hard-shelled hollow spheres with high silica and alumina content. These micron-sized aluminosilicate hollow spheres constitute only a small percentage of the coal fly ash (CFA) obtained from the coal combustion processes. In this study, cenospheres were separated from CFA obtained from a coal-fired power plant located in Kapar, Malaysia. The cenospheres were heated at 1000, 1200 and 1400 °C to study the changes in morphologies, compositions, phase formation and thermal expansion. The sintering temperatures were selected based on the differential scanning calorimetry (DSC) curve results. X-ray diffractometry (XRD), field emission electron microscopy (FESEM), energy dispersive spectroscopy (EDS) as well as thermogravimetry and differential scanning calorimetry analysis (TG–DSC) were used for the characterization study. The study found that the cenospheres have excellent weight stability but are thermally unstable as a result of crystallization and melting. The phase ordering process and devitrification of the amorphous aluminosilicate glass phase at high temperatures lead to the increment and enrichment of the mullite phase in cenospheres. It is suggested that a preheating treatment at 1100 °C could be used to enhance the mechanical properties and thermally stabilize the cenospheres, which make it more suitable for use as a pore-forming agent in ceramics.

scholarly journals Alumina Extraction from Coal Fly Ash via Low-Temperature Potassium Bisulfate Calcination

Minerals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 585 ◽  
Author(s):  
Chunbin Guo ◽  
Jingjing Zou ◽  
Shuhua Ma ◽  
Jianlin Yang ◽  
Kehan Wang
Keyword(s):  
Fly Ash ◽  
Low Temperature ◽  
Extraction Efficiency ◽  
Coal Fly Ash ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Increasing Demand ◽  
Technology Effects ◽  
Best Fit

Owing to the depletion of bauxite and increasing demand for alumina, calcination methods for extracting alumina from coal fly ash (CFA) were developed. However, these methods have disadvantages such as the need for high temperatures and the emission of toxic gases. Hence, in this study, Al2O3 was extracted from CFA via low-temperature potassium bisulfate calcination technology. Effects of the potassium bisulfate amount, calcination temperature, and calcination time on the alumina extraction efficiency were investigated using X-ray diffraction, thermal gravimetry, scanning electron microscopy, differential scanning calorimetry, and energy-dispersive spectroscopy. It was found that this technique could recover alumina efficiently, and potassium bisulfate significantly contributed to the degradation of mullite and corundum phases. Al2O3 in CFA was converted into soluble K3Al(SO4)3. With a KHSO4/Al2O3 molar ratio of 7:1, calcining temperature of 230 °C, and calcining time of 3 h, the alumina extraction efficiency reached a maximum of 92.8%. The Avrami–Erofeev equation showed the best fit with the kinetic data for the low-temperature calcination of CFA with KHSO4. The activation energy was 28.36 kJ/mol.

scholarly journals Catalytic Pyrolysis of a Residual Plastic Waste Using Zeolites Produced by Coal Fly Ash

Catalysts ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1113
Author(s):  
Marco Cocchi ◽  
Doina De Angelis ◽  
Leone Mazzeo ◽  
Piergianni Nardozi ◽  
Vincenzo Piemonte ◽  
...  
Keyword(s):  
Fly Ash ◽  
Energy Demand ◽  
Catalytic Pyrolysis ◽  
Low Cost ◽  
Coal Fly Ash ◽  
Plastic Waste ◽  
Scanning Calorimetry ◽  
Contact Mode ◽  
Degradation Temperature ◽  
Pyrolysis Oils

The plastic film residue (PFR) of a plastic waste recycling process was selected as pyrolysis feed. Both thermal and catalytic pyrolysis experiments were performed and coal fly ash (CFA) and X zeolites synthesized from CFA (X/CFA) were used as pyrolysis catalysts. The main goal is to study the effect of low-cost catalysts on yields and quality of pyrolysis oils. NaX/CFA, obtained using the fusion/hydrothermal method, underwent ion exchange followed by calcination in order to produce HX/CFA. Firstly, thermogravimetry and differential scanning calorimetry (TG and DSC, respectively) analyses evaluated the effect of catalysts on the PFR degradation temperature and the process energy demand. Subsequently, pyrolysis was carried out in a bench scale reactor adopting the liquid-phase contact mode. HX/CFA and NaX/CFA reduced the degradation temperature of PFR from 753 to 680 and 744 K, respectively, while the degradation energy from 2.27 to 1.47 and 2.07 MJkg−1, respectively. Pyrolysis runs showed that the highest oil yield (44 wt %) was obtained by HX/CFA, while the main products obtained by thermal pyrolysis were wax and tar. Furthermore, up to 70% of HX/CFA oil was composed by gasoline range hydrocarbons. Finally, the produced gases showed a combustion energy up to 8 times higher than the pyrolysis energy needs.

Mössbauer Spectroscopy Indicates That Iron in an Aluminosilicate Glass Phase Is the Source of the Bioavailable Iron from Coal Fly Ash

2000 ◽  
Vol 13 (3) ◽  
pp. 161-164 ◽  
Author(s):  
John M. Veranth ◽  
Kevin R. Smith ◽  
Frank Huggins ◽  
Autumn A. Hu ◽  
JoAnn S. Lighty ◽  
...  
Keyword(s):  
Mössbauer Spectroscopy ◽  
Fly Ash ◽  
Glass Phase ◽  
Mossbauer Spectroscopy ◽  
Coal Fly Ash ◽  
Aluminosilicate Glass ◽  
Mößbauer Spectroscopy

Characterization of fly ash from municipal solid waste incinerators using differential scanning calorimetry

1998 ◽  
Vol 321 (1-2) ◽  
pp. 133-141 ◽  
Author(s):  
Massimo Tettamanti ◽  
Elena Collina ◽  
Marina Lasagni ◽  
Demetrio Pitea ◽  
Domenico Grasso ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Fly Ash ◽  
Municipal Solid Waste ◽  
Solid Waste ◽  
Scanning Calorimetry ◽  
Waste Incinerators

scholarly journals PEMANFAATAN CAMPURAN ZEOLIT DAN FLY ASH BATUBARAYANG TELAH DIAKTIVASI FISIK TERHADAP AKSELERASI MESIN SEPEDA MOTOR 4-LANGKAH

2018 ◽  
Vol 7 (1) ◽  
Author(s):  
Herry Wardono ◽  
Ahmad Yudi Eka Risano ◽  
Adi Ernadi
Keyword(s):  
Energy Consumption ◽  
Fly Ash ◽  
Fossil Fuel ◽  
Gasoline Engine ◽  
Coal Fly Ash ◽  
Combustion Process ◽  
Engine Performance ◽  
Effect Of Temperature ◽  
Air Filter ◽  
Temperature Activation

Energy consumption in Indonesia is quite high, almost 96% is supplied from fossil fuel ( crude oil 48%, gases 18%, and coal 30%). From the total of energy consumption, it can be seen that almost 50% is gasoline. Thus, it is necessary to attain a certain aim in saving fossil fuel consumption. One of the ways is the utilization of zeolite and coal fly ash mixture as engine air filter. The mixture of zeolite and coal fly ash have a specific ability to trap nitrogen gases and water vapor in air, so that only oxygen enters the combustion chamber. Thus, the combustion process reaches the optimal condition and engine performance works better. Before applying, zeolite and fly ash were mixed with the comparisons of zeolite 0% : fly ash 100%, zeolite 25% : fly ash 75%, zeolite 50% : fly ash 50%, zeolite 75% : fly ash 25%, and zeolite 100% : fly ash 0%. The mixture of zeolite and fly ash was made in the form of pellet and activated physically within the temperature of 100 ºC (naturally), 150 ºC, 175 ºC, 200 ºC, and 225 ºC. Wheres various mass filter used were 50% (13,75 grams), 75% (20,62 grams) and 100% (27,50 grams). The pellets were arranged resemble a filter and place on the case of engine air filter. The purpose of this testing is to find out the effect of temperature activation and the filter mass variations as well as the composition of zeolite and fly ash mixture toward the performance of four step gasoline engine in acceleration testing. The best acceleration achieved is 12,61% (2,41 seconds faster ) taken from the test using filter of Z50:F50 mixture, with mass variation of 100% within temperature of 225 °C.Keywords: Filter of zeolite and coal fly ash,air adsorbent, engine acceleration.

scholarly journals Extraction of Al-Si master alloy and alumina from coal fly ash

2017 ◽  
Vol 53 (2) ◽  
pp. 155-162 ◽  
Author(s):  
A. Liu ◽  
Z. Shi ◽  
K. Xie ◽  
X. Hu ◽  
B. Gao ◽  
...  
Keyword(s):  
Fly Ash ◽  
Master Alloy ◽  
Power Plants ◽  
Coal Fly Ash ◽  
Raw Material ◽  
Aluminothermic Reduction ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray

Coal fly ash from coal power plants is a potential raw material for the production of alumina. An objective aluminothermic reduction method for the preparation of Al-Si master alloy and alumina from coal fly ash was investigated. The kinetic analysis using non-isothermal differential scanning calorimetry indicated that the reduction of Al6Si2O13, Fe2O3, and TiO2 by aluminum in coal fly ash occurs at 1618 K, 1681 K, and 1754 K, respectively. Moreover, the influence of reaction temperature on product composition was studied. The phases and morphologies of the products obtained by the aluminothermic reduction of coal fly ash at 1373-1773 K were analyzed by X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy, respectively. The results from X-ray diffraction show that no oxide reduction has taken place at 1373 K and 1473K, the compositions of the product obtained by aluminothermic reduction of fly ash at 1573K- 1673 K are Al2O3, mullite, Al and Si, while the compositions of the product at 1773 K are Al2O3, Al, and Si. In addition, the chemical compositions of Al-Si alloy obtained at 1773 K are 86.81 wt% Al and 13.19 wt% Si.

scholarly journals Effect of Temperature on Rare Earth Elements Recovery from Coal Fly Ash Using Citric Acid

2020 ◽  
Vol 742 ◽  
pp. 012040
Author(s):  
Pramesti Prihutami ◽  
Wahyudi Budi Sediawan ◽  
Widi Astuti ◽  
Agus Prasetya
Keyword(s):  
Rare Earth ◽  
Fly Ash ◽  
Citric Acid ◽  
Rare Earth Elements ◽  
Coal Fly Ash ◽  
Effect Of Temperature
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