Illinois Basin coal fly ashes.  1.  Chemical characterization and solubility

Roy, William R.; Griffin, Robert A.; Dickerson, D.R.; Schuller, Rudolph M.

doi:10.1021/es00128a003

Cited by 43 publications

(15 citation statements)

References 8 publications

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“…Metal retention in the residual fraction can be significantly reduced as suggested by Wu and Chen (1987) that more elements will be associated with leachable fraction (Exchangeable, reducible and organic bound fraction) than residual fraction if combustion conditions enhance volatilization-condensation conditions. Similar to our results Roy et al (1984) also showed that most of Zn may be found in the glassy matrix rather than as an adsorbed surface constituents or a soluble salt such as ZnSO 4 . H 2 O as proposed by Henry and Knapp (1980).…”

Section: Residual Fractionycrystalline Fractionsupporting

confidence: 92%

Speciation of some heavy metals in coal fly ash

Chaudhary

Banerjee

2007

Chemical Speciation & Bioavailability

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Selected heavy metals Cu, Ni, Zn and Pb were studied in two different types of coal fly ash samples, dyke and field, collected from Badarpur Thermal Power Station, Delhi, India for their total metal concentration as well as geochemical differentiation in different chemical fraction namely exchangeable, easily reducible or Fe -Mn bound, organic or sulfide bound and residual fractions. The total concentration of heavy metals in both types of fly ash samples followed the order Cr4Zn4Pb4Ni4Cu. Among the two types of samples, field fly ash samples were more enriched in these heavy metals compared with the dyke type samples. The fine grain size of field type samples possibly provided the sufficiently large surface area for the adsorption of these metals, resulting in higher concentrations compared with those in the coarse grained dyke samples. But, interestingly, the dyke type fly ash samples contain most of the metals in the exchangeable fraction. Metals in this fraction are easily mobilisable or can be made mobile depending upon the environmental conditions of Eh and pH. This suggests that the dyke type samples with low bulk metal content can even pose serious environmental hazards compared to the high total metal containing samples of field type. This suggests that it is the presence of metal in particular fraction(s) and not the total metal concentrations which are harmful to the environment, in particular to the soil and aquatic life.

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Section: Residual Fractionycrystalline Fractionsupporting

confidence: 92%

Speciation of some heavy metals in coal fly ash

Chaudhary

Banerjee

2007

Chemical Speciation & Bioavailability

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“…The identity of other phases is very difficult to establish because the patterns are characterized by a large number of small, overlapping peaks and the sample contains high quantities of poorly crystalline or amorphous materials. Quartz, hematite, and magnetite are also found to be dominant crystalline compounds in coal fly-ash (16)(17)(18)(19)(20) and in MSWI fly-ash (6,21,22). Mullite (3Al203.2Si02) is not identified in the ash sample, but is generally observed in coal fly-ash (19,23).…”

Section: Resultsmentioning

confidence: 99%

Morphological and Chemical Properties of MSWI Bottom Ash with Respect to the Glassy Constituents

Zevenbergen¹,

Wood²,

Bradley³

et al. 1994

Hazardous Waste and Hazardous Materials

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MSWI bottom ash consists predominantly of x-ray amorphous, glassy constituents. A thorough characterization of the glassy constituents could provide insight into both long term leaching and suitability for technological applications of MSWI bottom ash. In this study the bottom ash glasses were examined using conventional and advanced microanalytical techniques. The glass content of the bottom ash sample used in this study was estimated at 75% (w/w). Although the identity of all crystalline phases was very difficult to establish, seven minerals were identified. Automated particle analysis revealed that the major element composition (Si, Al, Ca and Fe) varies little with particle size for particles smaller than 1000 pm diameter, which may indicate complete transformation in this particle range. Inter particle heterogeneity is observed in ash particle composition, with varying quantities of network formers and modifiers. Reducing the scale of observation reveals the existence of different phases within individual particles. Over 50% of the surface area of the ash particles belong to silicon rich, calcium-silicon rich, and aluminum-silicon rich particles types. From a morphological and chemical point of view volcanic ashes and MSWI bottom ash exhibit a close similarity. Knowledge of weathering processes based on studies of volcanic ashes can be used to predict long term leaching behaviour of MSWI bottom ash.

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“…The alkaline-earth elements present on particle surfaces will be initially dissolved rapidly and pass into solution, but later, with increasing pH and element concentration, may re-precipitate to form secondary solids that are more stable during fly ash-water interaction [13].…”

Section: −1mentioning

confidence: 99%

Arsenic Leachability of Coal Fly Ashes from Different Types of Coal Fired Power Plants

Hartuti¹,

Kambara²,

Takeyama³

2017

JMSE-A

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Abstract:The leaching behavior of arsenic (As) in coal fly ash collected from two different types of coal fired power plants (unit 1 and unit 2: 600 MWe) has been investigated to understand their behavior during combustion and effect of different boiler types on arsenic leachability. To determine dominant factors on arsenic leaching from coal fly ash, the change of arsenic chemical during coal combustion was predicted from the perspective of thermodynamic equilibrium and leaching test under alkaline condition. It found that, arsenic leaching fractions in unit 1 were higher than that of unit 2, it is associated with the amount of reactive CaO (calcium oxide) containing in coal fly ash from unit 1 was lower than that from unit 2. As 2 O 3(gas) formed in the boiler reacts with CaO in the fly ash to form calcium arsenate Ca 3 (AsO 4 ) 2 which is thermodynamically stable calcium-arsenic compound. Hence the coal fly ash from unit 2 having higher CaO/Ash ratios generates more Ca 3 (AsO 4 ) 2 and has lower As leaching fraction than that from unit 1. CaO/Ash ratios were a promising index to reduce arsenic leachability from fly ash.

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Illinois Basin coal fly ashes. 1. Chemical characterization and solubility

Cited by 43 publications

References 8 publications

Speciation of some heavy metals in coal fly ash

Speciation of some heavy metals in coal fly ash

Morphological and Chemical Properties of MSWI Bottom Ash with Respect to the Glassy Constituents

Arsenic Leachability of Coal Fly Ashes from Different Types of Coal Fired Power Plants

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