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Title: Studies of the constitution of fly ash using selective dissolution
Authors: United States. Department of Energy.
Battelle Memorial Institute. Office of Nuclear Waste Isolation.
Buck, Alan D.
Husbands, Tony B.
Burkes, J. P.
Keywords: Chemical dissolution
Nuclear waste
Fly ash
X-ray diffraction
Radioactive waste disposal
Publisher: Structures Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Miscellaneous paper (U.S. Army Engineer Waterways Experiment Station) ; SL-83-5.
Description: Miscellaneous Paper
Abstract: Selective removal of the glassy phase from a fly ash permits determination of its amount and removes it as a diluent from the fly ash residue which if not removed, interferes with identification of crystalline phases by X-ray diffraction (XRD) or other methods. We tried and evaluated several types of selective chemical dissolution to determine glass content. We used changes in mass as measures of amount of glass and we identified the crystalline phases in the residues by XRD or optical microscopy. All chemical treatments that we tried had the disadvantage that none made an absolutely clean separation between glassy and crystalline phases. The two best methods were a treatment with fluosilicic acid and one with sodium hydroxide. We present details of each method. We concluded that chemical dissolution was a useful tool to estimate glass content and to assist in identification of crystalline phases. We judged the fluosilicic acid method to be the preferred procedure to estimate glass content of a fly ash. We give data for four lignite ashes, one subbituminous ash, and one bituminous ash. Glass contents ranged from 57 to 75 percent. Chemical analyses showed the presence of barium, titanium, strontium, and manganese in addition to other elements usually reported. We identified several phases similar to minerals containing these elements. It may not always be possible to determine whether a minor crystalline phase in the residue after chemical dissolution is an original mineral constituent of the coal, an original phase in the ash, or a product of the chemical treatment of the ash.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Miscellaneous Paper

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