Effect of water quenching and SiO2 addition during vitrification of fly ash

Kuo, Yi‐Ming; Wang, Jianwen; Wang, Chih-Ta; Tsai, Cheng‐Hsien

doi:10.1016/j.jhazmat.2007.07.081

Cited by 55 publications

(21 citation statements)

References 17 publications

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“…But there is tendency to narrow the crystallization temperature range with an increase of S/A and a significant shift to lower temperature when S/A reached 4.5. This is in agreement with the study that an increased alumina concentration can raise the T cv [44] and the addition of SiO 2 can promote the formation of an amorphous phase [45]. It should be noted that the phase determination was for the crystals under continuous cooling conditions.…”

Section: Discussionsupporting

confidence: 91%

Influence of SiO2/Al2O3 on crystallization characteristics of synthetic coal slags

Wang

Whitty

Guan

et al. 2015

Fuel

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Section: Discussionsupporting

confidence: 91%

Influence of SiO2/Al2O3 on crystallization characteristics of synthetic coal slags

Wang

Whitty

Guan

et al. 2015

Fuel

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“…There were no crystalline peaks in the slag pattern, which indicated the slags were amorphous and glassy. The result was similar to other researches [4,5,8,14].…”

Section: Characteristics Of Fly Ashes and Glassy Slagssupporting

confidence: 91%

“…Moreover, problem of soluble salts drew attention of system analysis: washing fly ash removed 30% up to 95% of chlorine, and achieved high removal rates of 30.7-72.8% of Ca, Na, K, and Cl at liquid-to-solid rates (L/S) of 10, whereas Pb, Cd and some minor elements were removed by 10-30% [10][11][12][13]. It was mentioned stability and leaching properties of glassy slags would be improved because of more network structures in slag after washing process [5,14]. But the effect of water-washing on volatilization and leaching behavior of heavy metals was scarcely reported.…”

Section: Introductionmentioning

confidence: 99%

“…But the effect of water-washing on volatilization and leaching behavior of heavy metals was scarcely reported. It has once reported that addition of SiO 2 enhances the glassy amorphous phase to produce more uniformly in slags [14,15], without any detailed interpretation. Many studies have been carried out on the toxicity of fly ash and leaching behavior of molten slag by different types of plasma furnaces.…”

Section: Introductionmentioning

confidence: 99%

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Volatilization and leaching behavior of heavy metals in MSW incineration fly ash in a DC arc plasma furnace

Fang

Chen

et al. 2017

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Keywords:MSW incineration fly ash Heavy metals Volatilization and leaching behavior DC arc plasma CaO -Al 2 O 3 -SiO 2 (CAS) A B S T R A C T Three fly ash samples collected from different waste incinerators were vitrified using a direct current arc plasma furnace at 1250-1400°C. The influence of water-wash extraction and wrapping pretreatment on the volatilization and leaching behavior of heavy metals was investigated. Results showed: After thermal arc plasma treatment, the volume reduction and weight loss of fly ash were in the range of 68.7-82.2% and 23.8-56.7%, respectively. The residual fractions (wt.%) of heavy metals in slag are in the following sequence: Cr < Ni < Cd < Pb < Cu < Zn. Water-washing could reduce the volatilization rate of heavy metals due to some volatile salts removed by washing, while wrapping of fly ash could most effectively resist heavy metals against volatilizing, especially for Zn and Ni. The possible CaO -Al 2 O 3 -SiO 2 (CAS) ratio for successful melting of fly ash is suggested to be CaO in range of 20-48%, Al 2 O 3 in range of 10-15%, and SiO 2 in range of 40-65%. Moreover, toxicity characteristic leaching procedure results showed that the leaching of heavy metals in slags was much lower than the standard limit of toxicity characteristic leaching procedure (TCLP).

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“…A 10% mass ratio of silicon (99+%) was homogeneously mixed with the specimens as an internal standard for crystalline semi-quantitative analysis (Kuo et al, 2008). The XRD intensity was measured in the 2θ range of 10° to 60° with Ni-filtered Cu Kα radiation at 4°/min (Chou et al, 2011).…”

Section: Methodsmentioning

confidence: 99%

Metal Distribution Characteristics in a Laboratory Waste Incinerator

Chang

Shen

Chou

et al. 2012

Aerosol Air Qual. Res.

Self Cite

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The metal distribution in the emissions of a laboratory waste incinerator (LWI) was investigated. The input materials and output materials (fly ash, bottom ash, and flue gas) were analyzed to examine the transportation and transmission behavior of heavy metals.Toxic (As, Cd, Cr, Hg, Ni, and Pb), anthropogenic (Ag, Ba, Cu, Mn, Se, and Zn) and crust (Na) elements were adopted to characterize the distribution properties of the LWI under investigation. The results indicated that Ba, Cr and Hg (80.0, 13.0 and 12.9 mg/L, respectively) were the major metals in the organic liquid waste input, and Na, and Zn (7497 and 349 mg/kg, respectively) were the major ones for medical solid waste. The Na content in the fly ash could be as high as 911574 mg/kg, and this was found to be the major Na emission source according to the emission factors. The mass of Na may be supplied using a NaOH solution injection to neutralize the acidic combustion gas, and it was found that high contents of Na in the flue gas were from the sprinkled NaOH solution. For the output materials, NaCl was found to be the major crystalline form of Na in the ash, based on the results of X-ray diffraction (XRD) patterns. The crust (Na) element was the major element in the bottom and fly ash. The toxic (As, Cr, Ni, and Pb) and anthropogenic (Se) elements were mainly distributed in the second cooling tower ash and baghouse ash in a range of 64.5%-91.9%. The average concentrations of Pb, Cd, and Hg concentrations in the flue gas were all under Taiwan's EPA regulation standards.Toxicity characteristic leaching procedure (TCLP) data showed that the leachability of As, Cr, Cu, Hg, and Se exceeded the EPA's regulations. It is thus suggested that the ash should be treated by further elutriation or vitrification processes to reduce the TCLP levels in the final products.

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Effect of water quenching and SiO2 addition during vitrification of fly ash

Cited by 55 publications

References 17 publications

Influence of SiO2/Al2O3 on crystallization characteristics of synthetic coal slags

Influence of SiO2/Al2O3 on crystallization characteristics of synthetic coal slags

Volatilization and leaching behavior of heavy metals in MSW incineration fly ash in a DC arc plasma furnace

Metal Distribution Characteristics in a Laboratory Waste Incinerator

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