Accession Number : ADA132041

Title :   Studies of the Constitution of Fly Ash Using Selective Dissolution.

Descriptive Note : Final rept.,

Corporate Author : ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS STRUCTURES LAB

Personal Author(s) : Buck,Alan D ; Husbands,Tony B ; Burkes,J Pete

PDF Url : ADA132041

Report Date : May 1983

Pagination or Media Count : 40

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. Tried and evaluated went several types of selective chemical dissolution to determine glass content. Changes in mass as measures of amount of glass and the crystalline phases in the residues were identified by XRD or optical microscopy. All chemical treatments that were 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. Chemical dissolution was a useful tool to estimate glass content and to assist in identification of crystalline phases. It was judged that fluosilicic acid method to be the preferred procedure to estimate glass content of a fly ash. Data is given for four lignite ashes, one subbituminous ash, and one bituminous ash. Glass contents ranged from 57 to 75 percent. Chemical analysis showed the presence of barium, titanium, strontium, and manganese in addition to other elements usually reported. Identified are 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, and original phase in the ash, or a product of the chemical treatment of the ash.

Descriptors :   *Fly ash, *Glass, *Chemical reactions, *Dissolving, Coal, Combustion, Residues, Phase, Crystals, Separation, Acids, Sodium hydroxide, Hydrofluoric acid, Concrete, Grout, Radioactive wastes, X ray diffraction, Chemical analysis

Subject Categories : Physical Chemistry
      Ceramics, Refractories and Glass
      Combustion and Ignition

Distribution Statement : APPROVED FOR PUBLIC RELEASE