Microwave sintering of fly ash containing unburnt carbon and sodium chloride

Fujii, Takashi; Kashimura, Keiichiro; Tanaka, Hironao

doi:10.1016/j.jhazmat.2018.12.114

Cited by 24 publications

(9 citation statements)

References 18 publications

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“…7. It can be seen that CaO, SiO 2 , Al 2 O 3 , SO 3 and Cl are the main compositions for sintered y ash, which is notable differences with raw y ash.…”

mentioning

confidence: 87%

Effects and mechanism of the conditions of sintering on heavy metal leaching characteristic in municipal solid waste incineration fly ash

Zhou

et al. 2022

Environ Sci Pollut Res

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Municipal solid waste incineration (MSWI) y ash treated with toxicity metals holds enormous potential for constructure use to economize on resources and protect environment. To reach the goal, this study investigated the effects of sintering conditions on leaching characteristic of heavy metals for MSWI y ash, especially Cr, Cr 6+ , Ag, and Ba, with orthogonal and Box-Benhnken design experiment, which considered grain size (D 50 =30, 45, and 60μm), uxing agent (CaO=0, 2.5, and 5%), setting temperature (1000, 1050, and 1100℃), and setting time (120, 180, and 240min). The mechanism of immobilization for heavy metals was also discussed through the analyses of morphological characterizations, mineral phases, chemical composition and leaching values of metals. The results indicated that changing grain size and adding uxing agent of CaO has positive in uence on reducing the leaching of heavy metals compared with direct sintering. The leaching values of As, Pb, Cd, Cu, Ni, Zn, Mn, Hg, Be, Se and uoride are not detected after sintering. Ideal sintered condition with desirability of 1.00 was predicted and optimized by Box-Benhnken response method in grain size of D 50 =30μm, uxing agent of CaO=5%, setting temperature=1050℃, and setting time=180min, which immobilized Cr, Cr 6+ , Ag, and Ba lower than the limitation of standards. Actual experiment was consistent with numerical optimization. Furthermore, the model of leaching characteristic for heavy metals in MSWI y ash was established to better explain the mechanism during sintering.

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“…7. It can be seen that CaO, SiO 2 , Al 2 O 3 , SO 3 and Cl are the main compositions for sintered y ash, which is notable differences with raw y ash.…”

mentioning

confidence: 87%

Effects and mechanism of the conditions of sintering on heavy metal leaching characteristic in municipal solid waste incineration fly ash

Zhou

et al. 2022

Environ Sci Pollut Res

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“…To this end, we exploit the characteristics of microwave heating to create a sintered body containing CaCO 3 in a single operation. Microwaves can heat y ash to 1000°C in tens of seconds [24], which indicates that sintering can be completed before the water molecules essential for CaCO 3 formation diffuse. In addition, we investigate an irradiation method that suppresses the decomposition of CaCO 3 and the combustion of unburned carbon by precisely separating the electric and magnetic elds of microwaves and irradiating the y ash raw material.…”

Section: Introductionmentioning

confidence: 99%

Manufacture of carbon storage sintered body using microwave-selective and high-speed heating techniques

Kashimura

Oshita²,

Miyata³

et al. 2023

Preprint

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Microwave sintering of fly ash samples with large amounts of unburned carbon and CaCO3 was examined in this study. To this end, CaCO3 was mixed with fly ash sintered body to fix CO2. The decomposition of CaCO3 was observed when the raw material was heated to 1000 ℃ using microwave irradiation; however, a sintered body containing aragonite was obtained when the raw material with water was heated to 1000°C. Further, carbides in the fly ash could be selectively heated by controlling the microwave irradiation. The microwave magnetic field created a temperature gradient of 100°C in a narrow region of 2.7 µm or less in the sintered body, and it helped suppress the CaCO3 decomposition of the mixture in sintering. By storing water in the gas phase, CaCO3, which is difficult to sinter with conventional heating, can be sintered without decomposing.

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“…To this end, we exploit the characteristics of microwave heating to create a sintered body containing CaCO 3 in a single operation. Microwaves can heat fly ash to 1000 °C within tens of seconds 24 , which indicates that sintering can be completed before the water molecules essential for CaCO 3 formation diffuse. In addition, we investigate an irradiation method that suppresses the decomposition of CaCO 3 and the combustion of unburned carbon by precisely separating the electric and magnetic fields of microwaves and irradiating the fly ash raw material.…”

Section: Introductionmentioning

confidence: 99%

Manufacturing carbon storage sintered body using microwave-selective and high-speed heating techniques

Kashimura

Oshita

Miyata

et al. 2023

Sci Rep

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Microwave sintering of fly ash samples with large amounts of unburned carbon and CaCO3 was examined in this study. To this end, CaCO3 was mixed with fly ash sintered body to fix CO2. The decomposition of CaCO3 was observed when the raw material was heated to 1000 °C using microwave irradiation; however, a sintered body containing aragonite was obtained when the raw material was heated to 1000 °C with added water. Further, carbides in the fly ash could be selectively heated by controlling the microwave irradiation. The microwave magnetic field created a temperature gradient of 100 °C in a narrow region of 2.7 μm or less in the sintered body, and it helped suppress the CaCO3 decomposition in the mixture during sintering. By storing water in the gas phase before spreading, CaCO3, which is difficult to sinter using conventional heating, can be sintered without decomposing.

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Microwave sintering of fly ash containing unburnt carbon and sodium chloride

Cited by 24 publications

References 18 publications

Effects and mechanism of the conditions of sintering on heavy metal leaching characteristic in municipal solid waste incineration fly ash

Effects and mechanism of the conditions of sintering on heavy metal leaching characteristic in municipal solid waste incineration fly ash

Manufacture of carbon storage sintered body using microwave-selective and high-speed heating techniques

Manufacturing carbon storage sintered body using microwave-selective and high-speed heating techniques

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