Weathering processes in relation to leachate properties of alkaline fly ash
Results are presented for a column leaching experiment designed to evaluate the relationship among leachate properties, weathering processes, and solid phase characteristics of an alkaline fly ash. Fly ash was weathered with 0.005 mol/L H/sub 2/SO/sub 4/ in a series of five leaching columns. Acidification of the ash leachates occurred in a stepwise fashion involving three buffer stages. Chemical dissolution and mobilization of elements was greatest in the first column and decreased to minimal dissolution and maximum accumulation of weathered products in ash of the fifth column. Results indicated that unreacted fly ash consists of spherical micron-sized particles composed of mullite enclosed in a two-phase glassy matrix. The external glass was enriched in Ca, Mg, Fe, and Al. The interior glass matrix was composed primarily of Si and a major portion of the total Na and K. The ash also contained a highly reactive inorganic phase composed largely of submicron-sized CaO fragments on the surfaces of ash particles. Initial dissolution characteristics were dictated by the reactions of the CaO fragments and surface-associated soluble salts. Leachate characteristics were largely controlled by dissolution of the external glassy matrix after the rapid dissolution of surface salts. Solid state migration and removal of Na from the interior glassy matrix was active under acidic leaching conditions.
- Research Organization:
- Univ. of Alberta, Edmonton
- OSTI ID:
- 5879845
- Journal Information:
- J. Environ. Qual.; (United States), Journal Name: J. Environ. Qual.; (United States) Vol. 13:4; ISSN JEVQA
- Country of Publication:
- United States
- Language:
- English
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54 ENVIRONMENTAL SCIENCES
ACIDIFICATION
AEROSOL WASTES
AIR POLLUTION
ALKALI METALS
ALKALINE EARTH METAL COMPOUNDS
ALKALINE EARTH METALS
ALUMINIUM
ASHES
CALCIUM
CALCIUM COMPOUNDS
CALCIUM OXIDES
CHALCOGENIDES
DISPERSIONS
DISSOLUTION
ELEMENTS
ENVIRONMENTAL EFFECTS
FLY ASH
HYDROGEN COMPOUNDS
INORGANIC ACIDS
IRON
LEACHATES
LEACHING
MAGNESIUM
METALS
MINERALOGY
MIXTURES
OXIDES
OXYGEN COMPOUNDS
PARTICLE SIZE
POLLUTION
POTASSIUM
RESIDUES
SEMIMETALS
SEPARATION PROCESSES
SILICON
SIZE
SODIUM
SOLUTIONS
SULFURIC ACID
TRANSITION ELEMENTS
WASTES
WATER POLLUTION
WEATHERING