Bloating mechanism for coal ash with iron oxide

Lee, Ki Gang

doi:10.6111/jkcgct.2014.24.2.077

Cited by 14 publications

(3 citation statements)

References 6 publications

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“…The content of Fe 2 O 3 is considered to be a very important aspect related to bloating by the internal reduction of the aggregates. In the literature, there are many studies dealing with the Fe 2 O 3 content and the phenomenon of bloating due to internal reduction [11,36,37]. In those studies, an appropriate Fe 2 O 3 content is required, and the ACF 5 and ACF 10 mixtures appear to be most appropriate among the mixtures used in this experiment.…”

Section: Analysis Of Raw Materials and Mixturesmentioning

confidence: 99%

Chemical design of lightweight aggregate to prevent adhesion at bloating activation temperature

Wie

Lee

2020

Journal of Asian Ceramic Societies

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The purpose of this study is to control the viscous behavior of lightweight aggregates through the chemical design of a lightweight aggregates material in order to solve the problem of the adhesion of lightweight aggregates by viscous behavior in the bloating activation temperature range of lightweight aggregates. In order to induce a reduction of Fe 2 O 3 inside the aggregates, Fe 2 O 3 and carbon were added to acid clay so as to produce aggregate. The particle density and the water absorption rate of the aggregates were measured, the cross-section was observed with an optical microscope, and the distribution of hematite of the lightweight aggregates was confirmed by a 3D CT analysis. Pilot scale rotary kiln experiments were performed. The optimal additive contents for the production of lightweight aggregates using acid clay were 8-13 wt% of Fe 2 O 3 and 2-3 wt% of carbon. The addition of additives decreased the bloating activation temperature, and viscous behavior was promoted in the core portion of the aggregates, resulting in a difference in the melting point between the shell and the core. As a result, the occurrence of adhesion at the aggregates surface was suppressed.

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Section: Analysis Of Raw Materials and Mixturesmentioning

confidence: 99%

Chemical design of lightweight aggregate to prevent adhesion at bloating activation temperature

Wie

Lee

2020

Journal of Asian Ceramic Societies

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“…Part of the emitted gases (CO 2 ) is the result of oxidation of unburned carbonaceous materials and thermal decomposition of carbonates. Others are the effect of redox reactions (reduction of iron oxides, but also sulfates and sulfides), and some are the result of reactions between clay components and admixtures [17][18][19][20]. The gases formed during the reaction cannot escape from the sintered material, which causes bubble creation; however, sufficiently slow heating of the material allows to complete these reactions before sintering and closing the pores [21].…”

Section: Introductionmentioning

confidence: 99%

Thermal studies of fly ashes expansion

Wons

Rzepa

Reben

et al. 2020

J Therm Anal Calorim

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The object of this study is to investigate the thermal properties of fly ashes from the last, farthest dedusting zone in terms of their use as ceramic masses additives. Siliceous fly ash is valuable additive to ceramic mass, which not only reduces its plasticity, but also actively affects sintering process and shapes the properties of the final material. The finest fly ash fractions are potentially useful flux materials in ceramics; however, a significant limitation in their use is due to thermal expansion/ bloating occurring during high-temperature sintering. The bloating mechanism of fly ashes was investigated in relationship to their chemical composition with the use of DTA/TG/EGA analysis as well as high-temperature microscope. Chemical and phase compositions were studied by X-ray fluorescence and X-ray diffraction. Based on the results obtained, it can be concluded. The results indicate that bloating mechanism is caused by the co-occurrence of two phenomena accompanying sintering: appearance of high amount of liquid phase and simultaneous gas release from sintered material. The dominant mechanism is the simultaneous release of sulfur (IV) oxide and oxygen as a result of the redox reaction of removing SO 3 from the vitreous phase.Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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“…Consequently, research for the viable methods to reuse the waste becomes an urgent task to be investigated. [1][2][3][4][5] Domestically, various reports on the coal ash recycling and its feasibility study are available that include; for uses as a concrete admixture mainly utilizing the fly ash, as a filler material for road pavement, and as an aggregate for cement mortar replacing the smaller portion of aggregates. We have also involved in researches on the coal ash recycling, and recently, have extended our focus to the industrial wastes recycling especially for manufacturing of artificial lightweight aggregates (ALWA).…”

Section: Introductionmentioning

confidence: 99%

Bloating Mechanism for Artificial Light Weight Aggregate of Surface Modification with Coal ash

Lee¹

2015

J. Korean Ceram. Soc

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We manufacture artificial lightweight aggregates (ALWAs) using bottom-ash as the primary raw material. We coat the ALWA surfaces with low-melting point materials in order to enable them to bloat, which is essential to reduce the bulk density of the aggregate. Then, we sinter the prepared aggregates at 1000, 1100, and 1200 o C using either the direct or two-step firing schedules. Finally, we evaluate the properties of the fired samples through analyzing their bulk density, water absorption, and microstructure. The surface-modified samples result in a reduction of their bulk density by 0.3~0.4 g/cm 3 regardless of the firing method used. Based on these results, we conclude that this approach could provide a viable method for the mass-production of ALWAs from industrial waste such as bottom-ash.

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Bloating mechanism for coal ash with iron oxide

Cited by 14 publications

References 6 publications

Chemical design of lightweight aggregate to prevent adhesion at bloating activation temperature

Chemical design of lightweight aggregate to prevent adhesion at bloating activation temperature

Thermal studies of fly ashes expansion

Bloating Mechanism for Artificial Light Weight Aggregate of Surface Modification with Coal ash

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