Physico-chemical characteristics of European pulverized coal combustion fly ashes

Moreno, Natàlia; Querol, Xavier; Andrés, José Manuel Palao; Stanton, Kenneth T.; Towler, Mark R.; Nugteren, Henk; Janssen-Jurkovícová, Maria; Jones, M. R.

doi:10.1016/j.fuel.2004.06.038

Cited by 270 publications

(243 citation statements)

References 22 publications

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“…In alkaline environments, Al is leached as aluminate Al(OH) 4 -forms. It is for this reason that, for alkaline fly ash, the leached levels of Al from water-based tests (rarely exceeding 200 mg/kg, typically pH 9-12) (Baba and Kaya, 2004;Dubikova et al, 2006;EPRI, 1998;Moreno et al, 2005) are often higher than those of the TCLP (close to the detection limit in the large data set reported by EPRI, 1998). The drop in the Al leachability at pH11.5 is consistent with that of Si and other oxyanions, and is directly linked to the precipitation of ettringite (Cornelis et al, 2008;Jones, 1995 (Roy and Griffin, 1984), mullite is considered a non reactive mineral in aqueous solutions (Tishmack, 1996).…”

Section: Major Elements Aluminiummentioning

confidence: 91%

“…Given that a number of elements contained in fly ash are markedly pH sensitive, unified curves presenting the pH-dependent solubility of various elements are plotted where possible (Figure 1), after the compilation of data from various sources (Chandler et al, 1997;de Groot, 1989;Dubikova et al, 2006;Jankowski et al, 2004;Jones, 1995;Moreno et al, 2005;van der Sloot, 1990;Zandi and Russell, 2007). In interpreting the curves is important to bear in mind that a number of factors (e.g.…”

Section: Leaching Protocols and Regulationsmentioning

confidence: 99%

“…The leachable concentrations range over several orders of magnitude as a function of the mode of Ca occurrence and concentration in the fly ash, the proportion of each phase and the leaching test performed. With only water, the amounts of Ca leached could easily fall in the 100-15000 mg/kg range (Iwashita et al, 2005;Izquierdo et al, 2011;Medina et al, 2010;Moreno et al, 2005). The water extractable proportions measured for a large set of data are in the 7-14% range (Moreno et al, 2005;Nugteren, 2010;Ward et al, 2003),…”

Section: Calciummentioning

confidence: 99%

“…Negligible proportions of Fe were found to be leached from fly ash (Ward et al, 2003). Less than 10 mg/kg of Fe are leachable in near neutral and alkaline solutions, and concentrations in most cases are below the detection limit (Kim et al, 2003;Moreno et al, 2005). Iron in fly ash is mainly present as magnetite mixed in various proportions with hematite, although a minor proportion can be assimilated in the glassy matrix (Kukier et al, 2003).…”

Section: Ironmentioning

confidence: 99%

“…The concentrations of Mg leached in water range from non detectable to less than 1000 mg/kg, but commonly do not exceed 50 mg/kg (Iwashita et al, 2005;Moreno et al, 2005). Magnesium in alkaline fly ash is poorly leachable in water (<0.1%, Ward et al, 2003), but the mobility increases up to 4% in acidic fly ash.…”

Section: Magnesiummentioning

confidence: 99%

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Leaching behaviour of elements from coal combustion fly ash: An overview

Izquierdo

Querol

2012

International Journal of Coal Geology

632

379

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Coal-based power generation produces over 750 Mt of coal ash per year globally, but under 50% of world production is utilised. Large amounts of fly ash are either stored temporarily in stockpiles, disposed of in ash landfills or lagooned. Coal ash is viewed as a major potential source of release of many environmentally sensitive elements to the environment. This paper encompasses over 90 publications on coal fly ash and demonstrates that a large number of elements are tightly bound to fly ash and may not be easily released to the environment, regardless of the nature of the ash. This review provides an extensive look at the extent to which major and trace elements are leached from coal fly ash. It also gives an insight into the factors underlying the leachability of elements and addresses the causes of the mobility. The mode of occurrence of a given element in the parent coal was found to play an important role in the leaching behaviour of fly ash. The amount of calcium in fly ash exerts a dominant influence on the pH of the ash-water system. The mobility of most elements contained in ash is markedly pH sensitive. The alkalinity of fly ash attenuates the release of a large number of elements of concern such as Cd, Co, Cu, Hg, Ni, Pb, Sn or Zn among others, but at the same time, it enhances the release of oxyanionic species such as As, B, Cr, Mo, Sb, Se, V and W. The precipitation of secondary phases such as ettringite may capture and bind several pollutants such ash As, B, Cr, Sb, Se and V.

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Section: Major Elements Aluminiummentioning

confidence: 91%

Section: Leaching Protocols and Regulationsmentioning

confidence: 99%

Section: Calciummentioning

confidence: 99%

Section: Ironmentioning

confidence: 99%

Section: Magnesiummentioning

confidence: 99%

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Leaching behaviour of elements from coal combustion fly ash: An overview

Izquierdo

Querol

2012

International Journal of Coal Geology

632

379

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Heavy Metals

Aydın

2016

Handbook of Combustion

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Heavy metals in combustible materials such as fossil fuels, biomass, municipal and medical wastes, sewage sludges, and in industrial wastes such as slags, are important pollutants for the environment. The bottom ashes and fly ashes from the combustion and incineration processes contain heavy metals as enrichment products in significant ratios. Therefore, heavy‐metal enrichment after combustion and incineration processes have been extensively discussed in this chapter. The health effects of heavy metals are described, with special attention paid to safe use of the combustion and incineration residues and fly ashes. The utilization of residues and fly ashes in cement production, soil remediation, adsorption of different pollutants and heavy metal recovery are outlined, as well as the stabilization/solidification of ashes and slags.

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Upscaling of W zeolite direct synthesis from coal fly ash and its water adsorption capacity

Gamero-Vega

Medina-Ramírez

Khamkure

et al. 2019

J of Chemical Tech & Biotech

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BACKGROUND: Alkaline amorphization of fly ash (FA) and crystallization of the potassium W zeolite from the resultant amorphous materials was carried out at different scales by a straightforward hydrothermal method. The experimental factors and levels were evaluated during the FA amorphization study by variation of the metallic hydroxide, concentration, temperature and time for the hydrothermal reaction. RESULTS:The alkaline FA hydrothermal activation study quantified a set of optimal conditions to obtain amorphous materials easy to be recrystallized into W zeolite. The activation process at laboratory scale involved the hydrothermal treatment of 3.6 g FA with 74.43 mEq KOH dissolved in 21 mL water at 125 ∘ C for 4 h. A product with ≤94.7% of the amorphous phase was obtained. The direct zeolitization of FA was performed at 175 ∘ C for 16 h with a KOH:FA weight ratio of 0.33 and molar ratios of 1.64, 17.08 and 3.90 for SiO 2 :KOH, H 2 O:SiO 2 and SiO 2 :Al 2 O 3 , respectively. An amount of dried zeolitic material c.25% higher than the weight of FA used was obtained. CONCLUSION: Adsorbents formulated with the W zeolite showed higher water adsorption capacity than the commercial molecular sieves used by industry for drying wet natural gas.

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Physico-chemical characteristics of European pulverized coal combustion fly ashes

Cited by 270 publications

References 22 publications

Leaching behaviour of elements from coal combustion fly ash: An overview

Leaching behaviour of elements from coal combustion fly ash: An overview

Heavy Metals

Upscaling of W zeolite direct synthesis from coal fly ash and its water adsorption capacity

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